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We studied transposition in pigeons, using multiple-pair discrimination training. Four birds discriminated two pairs of circles:
1+ 2− and 5+ 6− or 1− 2+ and 5− 6+ (digits denote circle diameters and plus and minus signs denote reward and nonreward, respectively).
Four other birds discriminated four pairs of circles: 1+2−, 1+3−, 4+6−, and 5+6−or 1−2+, 1−3+, 4−6+, and 5−6+. Finally, 4
birds discriminated only one pair of circles: 1+ 2−, 1+ 2−, 5+ 6−, or 5− 6+. Testing included five new pairs—1/5, 2/3, 2/6,
3/4, and 4/5—that distinguished absolute from relational accounts of transposition. The pigeons’ relational responding rose
from one- to two- to four-pair training. The similarity of the testing stimuli to one another also affected relational responding:
Transposition increased with highly dissimilar stimuli. Neither Spence’s (1937) theory nor existing relational accounts could
predict the obtained pattern of relational responding. 相似文献
3.
Shao-zhi Zhang Xiao-yi Yu Guang-ming Chen 《Journal of Zhejiang University. Science. B》2012,13(3):213-220
Osteochondral allografting has been proved to be a useful method to treat diseased or damaged areas of joint surfaces. Operational
long-term stocks of grafts which supply a buffer between procurement and utilization would contribute to the commercialization
or industrialization of this technology. Vitrification has been thought to be a promising method for successful preservation
of articular cartilage (AC), but high concentration cryoprotectants (CPAs) are used which may cause high cellular toxicity.
An effective way to reduce CPA toxicity is to increase CPA concentration gradually while the temperature is lowered. Understanding
the mechanism of CPA permeation at subzero temperatures is important for designing the cryopreservation protocol. In this
research, the permeation of dimethyl sulfoxide (Me2SO) in ovine AC at subzero temperatures was studied experimentally. Pretreated AC discs were exposed in Me2SO solutions for different time (0, 5, 15, 30, 50, 80, and 120 min) at three temperature levels (−10, −20, and −30 °C). The
Me2SO concentration within the tissue was determined by ultraviolet (UV) spectrophotometry. The diffusion coefficients were estimated
to be 0.85×10−6, 0.48×10−6, and 0.27×10−6 cm2/s at −10, −20, and −30 °C, respectively, and the corresponding activation energy was 29.23 kJ/mol. Numerical simulation was
performed to compare two Me2SO addition protocols, and the results demonstrated that the total loading duration could be effectively reduced with the
knowledge of permeation kinetics. 相似文献
4.
石灰岩采石迹地对淮南城市景观生态有着强烈负面干扰.在调查研究基础上,提出对采石迹地景观生态重建的构想,其中包括建立林带廊道、景观生态水库等,此外,还提出了采石时的景观设计. 相似文献
5.
We compared acquisition and performance accounts of human contingency learning. After solving a discrimination in Phase 1,
in which Cue A predicted the occurrence of the outcome and Cue B predicted its nonoccurrence (A+/B−), a new discrimination
(X+/Y−) was superimposed in Phase 2 (AX+/BY−). The participants were finally trained in Phase 3 with the added discrimination,
which either maintained the same contingencies as those in Phase 2 (X+/Y−; Experiment 1) or reversed the contingencies (X−/Y+;
Experiment 2). According to competitive-learning theories (e.g., Rescorla & Wagner, 1972), there should be no learning of
the added discrimination in Phase 2, so that no advantage or disadvantage for this discrimination should be observed in Phase
3. In contrast, performance theories, such as the comparator hypothesis (Miller & Matzel, 1988), contend that learning of
the added discrimination in Phase 2 should proceed normally; so, in Phase 3, an advantage for the added discrimination should
be observed in Experiment 1, but a disadvantage should be observed in Experiment 2. Our participants learned about the added
discrimination and generally showed the effects predicted by the comparator hypothesis. 相似文献
6.
张伟 《宁德师专学报(自然科学版)》2008,20(1):21-25
森林景观是开展森林旅游的物质基础,其美学价值的高低直接影响森林景观区的游客数量．结合生产实际,就灵石山国家森林公园的森林景观美学价值采用国内较为流行的描述因子法,并首次提出把“游道观景设施”纳入森林景观美学评价因子中,进行定量评价,进而得出该公园的森林景观美学等级,同时,结合景观生态学原理提出改造的措施和建议,为森林景观所有者或经营者提供科学决策依据． 相似文献
7.
LU Bao - qi 《上海大学学报(英文版)》2005,9(4):365-368
Infrared （IR） absorption spectra and X-ray powder diffraction （XRD） patterrns of sexpenfine cat＇s eye from Sichuan Province have been investigated, and infrared absorption bands of the serpentine have been assigned in this paper. The results indicate that the bands near 3 600 - 3 700 cm^-1 belong to the stretching absorption band VOH, the bands in 948 - 1 100 cm^-1 axe assigned to the stretching vibraling band Usvo, and the bands at 600 570 and 440 cm^-1 respectively belong to the bending vibration band VOH, δMg-O and δSi-O. The serpentine cat＇ s eye includes two types： chrysotile and antigorite. Chrysotile has a sharp and intensive band at 3 688 cm^-1 and a weak band at 3 643 cm^-1 , while antigorite has only one intensive band in the region. At vibration band VSi-O, chrysotile and antigorite have a similar feature at 1 071 cm^-1, but the band at 980 cm^-1 in anfigorite has been split into two bands in chrysotile - a strong one at 1 027 cm^-1 and a weak one at 949 cm^-1. In addition, antigorite has a characteristic bending vibrating band δMg-O at 570 cm^-1. Based on the analysis of the feature of crystal structure, their IR differences axe well explained. 相似文献
8.
Shan-long Lu Xiao-hua Shen Le-jun Zoue Chang-jiang Li Yan-jun Mao Gui-fang Zhang Wen-yuan Wu Ying Liu Zhong Zhang 《浙江大学学报(A卷英文版)》2008,9(6):858-866
The classification of thematic mapper imagery in areas with strong topographic variations has proven problematic in the past using a single classifier, due to the changing sun illumination geometry. This often results in the phenomena of identical object with dissimilar spectrum and different objects with similar spectrum. In this paper, an integrated classification method that combines a decision tree with slope data, tasseled cap transformation indices and maximum likelihood classifier is introduced, to find an optimal classification method for thematic mapper imagery of plain and highland terrains. A Landsat 7 ETM＋ image acquired over Hangzhou Bay, in eastern China was used to test the method. The results indicate that the performance of the integrated classifier is acceptably good in comparison with that of the existing most widely used maximum likelihood classifier. The integrated classifier depends on hypsography （variation in topography） and the characteristics of ground truth objects （plant and soil）. It can greatly reduce the influence of the homogeneous spectrum caused by topographic variation. This integrated classifier might potentially be one of the most accurate classifiers and valuable tool for land cover and land use mapping of plain and highland terrains. 相似文献
9.
Jesse L. Hawke Sally J. Wadsworth Richard K. Olson John C. DeFries 《Reading and writing》2007,20(1-2):13-25
To test the hypothesis that the etiology of reading difficulties may differ for males and females in more severely impaired
samples, reading performance data from monozygotic (MZ), same-sex dizygotic (DZss), and opposite-sex dizygotic (DZos) twin pairs were analyzed using a model-fitting implementation of the DeFries-Fulker (DF) model (Purcell & Sham, 2003, Behavior genetics, 33, 271–278). Five non-independent samples were selected using cut-offs of −1 (N = 737 pairs), −1.5 (N = 654), −2 (N = 468), −2.5 (N = 335), and −3 (N = 198) standard deviations (s) below the mean composite reading score of control twins. Male/female gender ratios for children
with reading difficulties were significantly higher than 1.0 for all five samples and increased as a function of severity
(viz., 1.15, 1.17, 1.40, 1.61, and 1.88, respectively). When the DF model was fit to the data, estimates of heritability (h
g2) and shared environmental influences (c
g2) were not significantly different for males and females in any of the groups. Consequently, the most parsimonious model that
provided a good fit to the data at all five levels of severity equated the heritabilities and shared environmental influences
for males and females, and fixed the DZos coefficient of genetic relatedness at 0.5. Thus, these results provide no evidence for a differential etiology of reading
difficulties as a function of gender in more severely impaired samples, and suggest that the same genetic and environmental
influences contribute to reading difficulties in males and females, irrespective of severity. 相似文献
10.
湿地公园景观格局是不同类型、不同大小、不同形状的地块在空间上构成的镶嵌体。景观镶嵌结构的差异反映出不同的功能。通过计算一些景观指数,对大九湖湿地公园景观格局作出定量分析。结果表明:①林地占研究区总面积的47.55%,因其面积最大而成为整个景观的基质;②人类不合理的开发利用严重破坏了湿地功能;③人类活动强烈的景观要素中,表征复杂的景观指数较高。 相似文献
11.
This study aims at highlighting young children’s reasoning about human interventions within a forest ecosystem. Our focus
is particularly set on whether preschoolers are able to come up with any basic ecological interpretations of human actions
upon forest plants or animals and how. Conducting individual, semi-structured interviews with 70 preschoolers (age 4–5), we
first tested their ability to consider the forest as a habitat and recognize simple food chains in it, and then we traced
their reasoning about the consequences that human actions upon plants or certain forest animals may possibly have for other
animals that also live in the forest. The analysis of our qualitative data with “NVivo” software does reveal an ecological aspect in preschoolers’ reasoning, which is thoroughly discussed in the paper. 相似文献
12.
Pakistani wheat varieties are grown over a wide agro-climatic range and as such are anticipated to exhibit yield and quality differences. It is therefore necessary to investigate the nutritional status of wheat varieties in terms of biochemical and physiochemical characteristics available for food and nutritional purposes in Pakistan. The result shows that wheat grains of different varieties contain a net protein level of 9.15%～10.27%, 2.15%～2.55% total fats, 1.72%～1.85% dietary fibers,77.65×10^-6～84.25×10^-6 of potassium and 7.70× 10 6～35.90× 10^-6 of sodium ions concentration, 0.24× 10^-6～0.84× 10^-6 of phosphorus, 1.44%～2.10% ash, 31.108～43.602 g of thousand grain mass （TGM） and 8.38%～9.67% moisture contents. This study is significant in providing an opportunity to explore the available wheat varieties and to further improve their nutritional excellence and also essential for setting nutritional regulations for domestic and export purposes. 相似文献
13.
In this paper, a new ternary non-azeotropic mixture of HFC-161/125/143a (0.15/0.45/0.40 in mass fraction), as a promising
mixed refrigerant to R404A, is presented. The ozone depletion potential (ODP) of the new refrigerant is zero and its basic
thermodynamic properties are similar to those of R404A, but its global warming potential (GWP) is much smaller than those
of R507A and R404A. Meanwhile, theoretical calculations show that, under the working condition I (the average evaporation
temperature: −23 °C, the average condensing temperature: 43 °C, the superheat temperature: 28 °C, the subcooling temperature:
5 °C), the volumetric refrigerating effect and specific refrigerating effect of the new mixture are 2.33% and 15.48% higher,
respectively, than those of R404A. The coefficient of performance (COP) of the new mixture is 5.19% higher than that of R404A
and the pressure ratio of the new mixture is 0.82% lower than that of R404A. Equally, under the working condition II (the
average evaporation temperature: −40 °C, the average condensing temperature: 35 °C, the superheating temperature: 30 °C, the
subcooling temperature: 5 °C), the volumetric refrigerating effect and specific refrigerating effect of the new mixture are
2.24% and 20.58% higher, respectively, than those of R404A. The COP of the new mixture is 4.60% higher than that of R404A
and the pressure ratio of the new mixture is similar to that of R404A. The performances of the new mixture and R404A are compared
in a vapor compressor refrigeration apparatus originally designed for R404A under several working conditions (condensing temperatures:
35–45 °C, evaporation temperatures: −40–−20 °C). Experimental results show that the new mixture can obtain a higher COP, by
6.3% to 12.1%, and a lower pressure ratio, by 1.8% to 6.6%, compared to R404A; although the discharge temperature of the new
mixture is slightly higher than that of R404A. The advantages of the new mixture will be further verified in the actual system. 相似文献
14.
In a simultaneous discrimination involving a positive (S+) and a negative (S−) stimulus, positive value appears to transfer from the S+ to the S−. However, negative value does not appear to transfer from the S− to the S+. Instead, when sufficient experience with the contingencies associated with responding to the S− is provided, it appears that the presence of the S− enhances the value of the S+ (i.e., a contrast effect is found). The purpose of the present experiments was to further examine the influence of the S+ on the S− in a simultaneous discrimination (between subjects in Experiment 1 and within subjects in Experiment 2). In both experiments, we found that under typical training conditions, given little direct experience with the value of the S−, value transfers from the S+ to the S−. If sufficient experience with the value of the S− is provided, however, contrast between the S+ and the S− can be demonstrated. Thus, in a simultaneous discrimination, value transfer from the S+ to the S− depends on the animal’s having responded relatively little to the S−. 相似文献
15.
A laboratory incubation experiment was conducted to study the effect of copper as cupric sulfate (CuSO4.5H2O), and lead as lead acetate (Pb (OAc)2) on the size of the microbial biomass in red soil. The metals were applied, separately at six different levels: Cu at 50,
100, 200, 300, 400, and 600 μg·g−1 soil and Pb at 100, 200, 400, 600, 800, and 1000 μg·g−1 soil. In comparison to uncontaminated soil, the microbial biomass carbon (Cmic) and biomass nitrogen (Nmic) decreased sharply in soils contaminated with Cu and Pb. The microbial biomass C:N ratio in the metal contaminated soil was
observed to be considerably higher than that in untreated control. Between the two tested metals, Cu displayed greater biocidal
effect on microbial biomass carbon and nitrogen than Pb, showing their relative toxicity in the order: Cu≫Pb.
Project (No. 49671050) supported by National Natural Science Foundation of China.
Wa’el Mohamad—Former Ph. D. Student of Zhejiang University and is working in Ministry Of Agriculture (P. O. box. 2099), Amman,
Jordan. 相似文献
16.
城区旅游景观规划设计初探--景观生态学的启示 总被引：2，自引：0，他引：2
刘连中 《内江师范学院学报》2003,18(4):42-46
借用景观生态学的有关概念、术语，如斑块、廊道、基质及其相关指标系数，利用景现生态学的景现规划原则、原理、规划步骤构建了城区旅游景观开发的可操作性的理论模式。 相似文献
17.
Studies were initiated for two consecutive years to find out the effect of time of transplanting and seedlings hill^-l on the productivity of rice in Dera Ismail Khan district of North West Frontier Province （NWFP）, Pakistan. The experiment was laid out in a randomized complete block design with split plot arrangements. Main plots consisted of four transplanting dates viz. 20th and 27th of June and 4th and 1 lth of July while sub-plots contained 1, 2, 3 or 4 seedlings hill^-1. Among transplanting dates, June 20th planted crop gave highest paddy yield and net return with I seedling hill^-1. It explains that the use of more seedlings hill^-1 not only adds to cost but is also a mere wastage of natural resources. Based on research findings, we conclude that the use of I seedling hill^-1 is most appropriate for timely sowing otherwise 4 seedlings hill^-1 should be used to compensate for the yield gap in late transplanted rice. 相似文献
18.
In this study aimed to evaluate the pollution extent of metals and nonmetals inside and outside the ferrosilicon production factory in Edfu, Aswan, Egypt, raw materials (quartz, cokes, iron oxides), ferrosilicon alloy, silica fume, dust and suspended dust (at different sites) samples were collected from the factory, and fallen dust samples were collected from outside the factory, horizontally (at different sites and different distance and directions) and vertically (at different floors in the selected buildings). Gravimetric methods, X-ray fluorescence (XRF), flame photometer, wide range carbon determinator and atomic absorption spectroscopy tools were used for elements determination. The results indicating that the fallen dust and its element contents on southern factory walls being higher than those on eastern factory walls may be due to the nature of the dusts and effects of wind force and wind direction. Fallen dust levels in different regions outside the factory were found to be affected by the distance, direction and floors. The nature of dust samples was affected by gravity and the suspended dust in different factory units depended on the work capacity and method of handling materials by personnel in different production units. Silica fume was a complicated problem, had dangerous effect against the workers' health, and was characterized by high concentrations of SiO2(90.6%～93.6%) and heavy metals (Mn, 420.6×10-6～520.3×10-6; Fe, 2354×10-6～2685×10-6; Co, 80.7×10-6～101.6×10 6 and Ni,5.3× 10-6～6.05× 10-6). The TSP (Total Suspended Particulate) levels in all factory units were higher than the recommended air quality value (70 μg/m3) under Egyptian law. The effect of ferrosilicon factory fallen dust on the surrounding regions decreased with increasing distance between the factory and these regions. The suspended dust samples in the factory units and their components greatly exceeded national and international standards, so health and environmental criteria must be enforced on these units. 相似文献
19.
Vashist SK Kaur I Bajpai RP Bharadwaj LM Tewari R Raiteri R 《Journal of Zhejiang University. Science. B》2006,7(9):683-685
We report an important observation that the surface conductivity of antibody layer immobilized on polylysine-coated glass
substrate decreases upon the formation of complex with their specific antigens. This change in conductivity has been observed
for both monoclonal and polyclonal antibodies. The conductance of monoclonal mouse IgG immobilized on polylysine-coated glass
substrate changed from 1.02×10−8 Ω−1 to 1.41×10−11 Ω−1 at 10 V when complex is formed due to the specific biomolecular interactions with rabbit anti-mouse IgG F(ab′)2. Similar behavior was observed when the same set up was tested in two clinical assays: (1) anti-Leishmania antigen polyclonal
antibodies taken from Kala Azar positive patient serum interacting with Leishmania promastigote antigen, and (2) anti-p21
polyclonal antibodies interacting with p21 antigen. The proposed concept can represent a new immunodiagnostic technique and
may have wide ranging applications in biosensors and nanobiotechnology too. 相似文献
20.
The effects of the concentration of dissolved total organic carbon (TOC), the TOC/Br- ratio, bromide ion levels, the chlorine to ammonia-N ratio (Cl:N), the monochloramine dose and the chlorine dose on the formation of trihalomethanes (THMs) (including chloroform, bromodichloromethane, chlorodibromomethane, and bromoform) from chlorination were investigated using aqueous humic acid (HA) solutions. The profile of the chloramine decay was also studied under various bromide ion concentrations. Monochloramine decayed in the presence of organic material and bromide ions. The percentage of chloroform and brominated THMs varied according to the TOC/Br- ratio. Total THMs (TTHMs) formation increased from 112 to 190 μg/L with the increase concentrations of bromide ions from 0.67 to 6.72 mg/L, but the chlorine-substituted THMs were replaced by bromine-substituted THMs. A strong linear correlation was obtained between the monochloramine dose and the formation of THMs for Cl:N ratios of 3:1 and 5:1. These ratios had a distinct effect on the formation of chloroform but had little impact on the formation of bromodichloromethane or chlorodibromomethane. The presence of bromide ions increased the rate of monochloramine decay. 相似文献