共查询到20条相似文献，搜索用时 31 毫秒
1.
Type Ⅰ,Ⅲ and Ⅴ collagens were extracted from bovine dermis and cornea by using pepsin treatment in acetic acid solution,followed by salt precipitation and dialysis,to purify and isolate each type of collagens.The preparation process was analyzed by using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE).A reducing agent,2-mercaptoethanol,was used to remove disulfide bonds and analyze the structure of the bonds involved between α chains in some types of collagens.The use of delayed reducing methods resulted in the difference between α1(Ⅲ) and α1(Ⅰ) chains in a mixture containing type Ⅰ and Ⅲ collagens.The structure of disulfide bonds among α chains exists potentially in type Ⅴ collagen prepared from the pepsin-treatment extraction at 4℃,which differs from type Ⅲ collagen in relation to the locations of disulfide bonds.Compared with pepsin-treated collagen at 4℃,the relative molecular weights of α1(Ⅴ) and α2(Ⅴ) chains treated at room temperature decrease by 4.6% and 6.0%,respectively.It is concluded that type Ⅰ,Ⅲ and Ⅴ collagens can be prepared from bovine dermis and cornea by the use of pepsin treatment,salt precipitation and dialysis.The interchain disulfide bonds lie potentially near the edges of termini of type Ⅴ collagen molecules in extracellular matrix,and a small number of interchain crosslinks exist in type Ⅴ collagen. 相似文献
2.
3.
This study examined the NNSs’ ability of modifying their interlanguage utterances in modified comprehensible output to give response to other-initiation and self-initiation,which was studied in both NS-NNS and NNS-NNS interactions.It was the qualitative study by using two different tasks which were picture-dictation task and opinion-exchange task to collect the data.There were 32 participants whose age ranged of 22 to 37.The author proposed two hypotheses based on his expectation that NNS-NNS interactions would provide more opportunities for NNS participants to give comprehensible output for other-initiated clarification requests and self-initiated clarification attempts than NS-NNS interactions.The author was good at using numbers to illustrate and describe the data in his writing. 相似文献
4.
One of the objectives of Malaysia Ministry of Education is to provide educational opportunities for all Malaysians. Are education opportunities given fairly to all Malaysians who come from two big regions and divided by the South China Sea？ The web infancy era, where the World Wide Web （WWW） is blooming fast, has changed the new millennium teaching and learning process tremendously. Although the online learning can reach to students regardless of their location and backgrounds, human contact is still very important in traditional face-to-face learning. Blended learning course comprising online learning and traditional face-to-face learning components is an effective teaching and learning method, where it combines the best from both worlds. Blended learning courses only started a few years ago in Malaysia higher learning institutions to give everybody equal opportunities to study. The key acceptance of blended learning approach and continuing improvement is students＇ satisfaction. This study focused on students＇ satisfaction related to the nine components of blended learning （course content, technical, flexibility, community learning, motivation, sharing, feedback, complementary learning and personalized learning） from two locations： urban and rural areas. The study employed a mixed method consisting of a survey questionnaire distributed first to collect the quantitative data and followed by the interview to refine and explain the data. The population of the study consisted of students who enrolled in the Mathematics Blended Learning Course in Sarawak state in semester July-November, 2007. Census was used in the study. The survey instrument was developed and validated using Rasch model. The semi-structured questionnaire was used in qualitative data collection. The quantitative data was analyzed by using SPSS v 14.0 whilst the qualitative data was coded by using NVivo software. Results from the quantitative data showed that students were satisfied in all nine components regardless of the location. The grand mean of all components also indicated that respondents were satisfied with blended learning course. This result was supported by the qualitative data. 相似文献
5.
Preparation and Characterization of M-Type Barium Ferrite Fibers via Aqueous Sol-Gel Process 总被引：1，自引：0，他引：1
BaFe12O19 fibers was prepared via an aqueous sol-gel process using Fe(OH)(HCOO)2 synthesized in laboratory and Ba(CH3COO)2 as the original materials and citrate as the chelate. The rheological behaviour of spinnable sol was characterized on rheometer, and the development of gel fibers to barium ferrite fibers was studied by IR, TG and XRD. Morphology observation of the fibers was given on SEM, and the diameter of the obtained fibers was between 5 and 10 μm corresponding to different additives. The additives affected the surface tension of the precursor sol which had close relation to the microstructure of fibers. Sucrose and hydroxyethylic cellulose could improve the surface tension while diethanolamine and hexadecylamine reduce that of the precursor sol. And using diethanolamine or hexadecylamine as an additive, well-structured BaFe12O19 fibers could be obtained. 相似文献
6.
7.
The influence of water on protein conformation was investigated by simulating the molecular dynamics of a model protein lysozyme in different water systems.The lysozyme-water system with TIP3P water model and lysozyme-water cluster system with six-ring water model were evaluated.In addition,the radial distribution function of solvent around lysozyme was calculated.It is found that the distribution of water molecules around lysozyme is similar to that of water clusters.The analyses of dihedral angles and disulfide bonds of lysozyme show that the conformation of lysozyme is severely damaged in the lysozyme-water cluster system compared with that in the lysozyme-water system.This difference can be attributed to the formation of larger number of intermolecular hydrogen bonds between lysozyme and water cluster.It is in agreement with the analysis that water clusters can change the degree of denaturation in the process of heat denaturation of lysozyme. 相似文献
8.
Sebnem Kandil lngec Serap Aga Mina Sahingoz 《美中教育评论》2014,(12):823-841
This study aims to measure girls＇ technical and vocational high school students＇ information and communication technology （ICT） skills and to investigate these in terms of different variables. The singular and relational survey model was used in this study. The sample composed of 119 technical and vocational high school students. The data were collected through a paper-based survey composed of two parts. In the first part of the survey, there are 15 items about personal information and demographic information about the participating students. In the second part, there is a scale about ICT skills. The data were analyzed by Statistical Package for Social Sciences （SPSS） Version 21.0 by means of percent, frequency, mean, mode, median, Mann-Whitney U, and Kruskall-Wallis test. The results showed that there were no significant differences in the technical and vocational high school students＇ ICT skills with respect to gender, class level, experience in the use of computers, frequency of using the Internet, working style, learning style, and motivation style. As for the ＂number of aim using the Internet＂ variable, a significant difference in the ICT skills scale was observed. 相似文献
9.
Education is the backbone for the development of society. With the advent of technology, it is becoming necessary and being used for the advancement of society. Technology is being used for education as being used in other important fields of life. Usage of technology for education can play a big part in bringing improvement in education For this purpose, this research aims to explore the usage and effects of technology for education. While using the survey method, a questionnaire was constructed for data collection. The sample of the study consists of graduate and postgraduate students from both ODL and regular universities and the sample size would be of 300 respondents （150 from each type of university） who were selected by using simple random sampling. The present study concluded that technology is widely used by both regular and ODL students. This study further concluded that ODL students are more dependent on technology as compared to regular students. 相似文献
10.
The solubilities of 2-naphthalenesulfonic acid monohydrate and sodium 2-naphthalenesulfonate in sulfuric acid solutions were measured at temperatures ranging from 278.15 to 338.15 K by using a dynamic method. The concentration of sulfuric acid solution ranged from 0 to 80wt%,. The solubilities of 2-naphthalenesulfonic acid monohydrate and sodium 2-naphthalenesulfonate increased with temperature, and both of them were the lowest at 70wt %, of sulfuric acid solution(w~0_3 =0.70)while the highest in pure water. The solubility data were correlated by the modified Apelblat equation. Based on the solubility difference between 2-naphthalenesulfonic acid monohydrate and sodium 2-naphthalenesulfonate, a new technique in which sodium sulfate was used to replace sodium sulfite in the neutralization reaction was developed. The suitable mole ratio of H_2O to Na_2SO_4 in the neutralization reaction was 80∶1, and that of 2-naphthalenesulfonic acid monohydrate to Na_2SO_4 was 3.2∶1. The material balance under the suitable mole ratios was given and discussed. 相似文献
11.
Resonant tunneling diode （RTD） of AlAs/InGaAs/AlAs double barrier-single well structure was designed and fabricated. The devices showed current-voltage characteristics with peak-valley current ratio of 4 ： 1 at room temperature. The scattering parameter of RTD was measured by using an HP8510（C） network analyzer. Equivalent circuit parameters were obtained by curve fitting and optimized. The RTD switching time was estimated using the measured capacitance and average negative differential resistance. The minimum rise time of the sample was estimated to be 21 ps. 相似文献
12.
It‘s importat that HTS tapes have lower thermal conductivity and higher transversal resistivity in order to reduce the heat leaks conducted along the tapes and AC losses in the high temperature superconducting system conduction-cooled by GM coolers,This paper presents an experimental investigation into the effects of pure Ag and AgAu alloys sheath materials on the properties of Bi(2223) multifilamentary tapes and the optimisation of conduction-cooled hybrid current leads made from copper and Bi(2223)/Ag or Bi(2223/)AgAu tapes,The thermal conductivity of the tapes were measured by cryogenic steady healt flux method and the resistance was measured by using standard DC four-probe method at lo temperature,The results showed that the reduction of thermal conductivity by the addition of Au into the sheath material of Bi(2223) tapes was 65%,75% and 85% lower than that of pure Ag sheathed Bi(2223) tapes and the increase of resistivity was 4.9,10 and 19.4 times higher than that of pure Ag for the addition of 2.2%,5.7% and 10.7% Au(atom ratio )respectively.And the study also attempts to optimise thermodynamically the conduction-cooled hybrid current lead by using a devel-oped model ,which took the irrevesibility of commercial GM coolers,the contact resistance and thermal conductance into account,Predictions from the model showed that AgAu alloys were suitable candiate materials to replace Ag as sheath material of Bi(2223) tapes applied in THS current leads,In addition,Bi(2223)/AgAu was a suitable material to be applied as the THS section of hybrid current leads in conduction-coled superconducting electric systems. 相似文献
13.
Under extreme loading condition,a shelter will provide a safe place to protect people from injury caused by blast wave and fragments.In order to save resource and reuse waste materi-als,a new design concept for blast protection shelter was explored.The new construction was composed of I-section steel panel or C-channel steel panel filled with recycled concrete aggregate.The compaction process of the recycled concrete aggregate filled in the steel construction was ex-perimentally investigated.A single storey shelter based on the proposed design concept was nu-merically simulated by using LS-DYNA software.In the 3D numerical model,three walls were de-signed using I-section steel and one wall using C-channel steel,and all of the four walls were filled with recycled concrete aggregate.The penetration analysis was done by using ConWep.Some penetration tests were also carried out by using a gas gun.It is found that the proposed shelter based on the design concept is effective for blast protection. 相似文献
14.
WEI Kang SHAMSI Imran Haider ZHANG Guo-ping 《Journal of Zhejiang University. Science. B》2007,8(4):266-271
The effects of salinity （50 mmol/L NaCI） and Cd （1 μmol/L CdCl2） as sole and combined on growth and photosynthetic parameters were studied using two soybean genotypes, Huachun 18 and NGB. The concentrations of Cd^2＋, Zn^2＋, Ca^2＋, Mg^2＋, K^＋ and Na^＋were also determined in seeds and pods. Huachun 18 suffered a more serious decrease than NGB in net photosynthetic rate （P,） in the treatments of salinity stress alone and combined stress （NaCl＋Cd）, showing that it is relatively sensitive to salinity. The decrease in P, caused by salt stress in Huachun 18 was mainly due to the reduced total chlorophyll content and photosynthetic efficiency （the ratio of variable fluorescence to maximal fluorescence, Fv/Fm）, whereas the decease in NGB was mainly related to reduced stomatal conductance （Gs）, The combined stress of both Na and Cd did not induce further decrease in photosynthesis and fluorescence in the two genotypes relative to salt or Cd stress alone. Greater change in the pod concentrations of Zn^2＋, Ca^2＋, Mg^2＋, K^＋ and Na^＋was detected under salt stress for Huachun 18 than for NGB. The results suggested that the interactive effect of NaCl-Cd on growth and nutrient uptake differs between the two soybean genotypes. 相似文献
15.
ZHUHuai－liang 《上海大学学报(英文版)》2001,5(1):35-39
In this paper ,a hybrid approach was developed to investigate the transient responses of a multi-span non-uniform flexble spinning shaft with nonlinear and asymmetric supports.The non-uniform spinning shaft with variable parmeters was modeled as a Bernoulli-Euler beam column with sectional constant cross-section properties by the finite element method.The supporting stiffness behavior of the nonlinear supports was described as a piecewise-linear and asymmetric model.The equations of motion in the matrix form of a multi-span non-uniform spinning shaft with nonlinear and asymmetric supports were formulated using Hamilton‘s principle and the assumed mode method.As an example,a spinning rocket with many variable stiffness supports was numerically simulated by the direct integration method.The transient response and dynamic behavior of this rotate-dynamic system are analyzed. 相似文献
16.
Based on the Leaderman constitutive relations in nonlinear viscoelasticity and the linear geometrical assumption, a mathematical model for the bending of nonlinear viscoelastic beams was established in this paper. The Laplace transformation method and the Titchmarsh theorem were used to prove that some relations exist between solutions to bending problems of visco- and elastic beams, which reveals the fugue effect of viscoelastic materials. The high-order Galerkin approximate solution to the quasi-static response of nonlinear viscoelastic beams under a step load was obtained by using the new method suggested in this paper as well as the Mathematica software and the Newton iteration technique. 相似文献
17.
The negative valve overlap (NVO) strategy of HCCI operation was experimentally investigated on a gasoline HCCI engine operated with variable valve timing in association with the addition of diesel fuel. The experimental results show that, by using gasoline and diesel blended fuels, the required NVO interval for suitable HCCI combustion under a given engine speed and a moderate compression ratio condition could be reduced, and the HCCI combustion region was extended remarkably without substantial increase in NOx emissions under a given inlet and exhaust valve timing due to the improvement of charge ignitability. In addition, the possible scale of NVO was extended. A substantial increase in the lean limit of excess air ratio and the upper limit of load range can be achieved because of higher volumetric efficiency, resulting from the decrease in the required NVO and the presence of less residual gases in cylinder. 相似文献
18.
19.
Dennis Ping-Cheng Wang 《美中教育评论》2010,7(7):43-52
The Orff music method has been internationally practiced and recognized as one of the leading music methods in the past fifty years. The success of this approach is that this method encourages all students participating in the designed music activities in the music class to interact with the teacher and other classmates using the Orff approach rather than the traditional one-way music learning approach in the traditional music classroom in Asia. While the children are situated within an environment where music activities and bodily movements are stimulated, the children＇s aesthetic music knowledge can be influenced significantly （Carlson, 1990）. In this study, there were a total number of 180 3rd graders from three elementary schools in Taiwan who participated in this research. The control group which consisted of three classes with a total number of 90 students was the class using the traditional music method taught by a regular classroom teacher, while the experimental group, which consisted of another three classes with a total number of 90 students, was the class taught using the Orff music method by the researcher. The study was controlled in the sense that the six music classes were ascertained to be of equal ability in their understanding of music before the experimental factor was applied. As well, there were no significant differences in age or mental capacity, while the difference in genders was only minimal. The results of this research revealed that not only did the students who had the Orff music method training perform better than the traditional music method on both melodic patterns dictation and music reading tests, but the Orff training also helped the experimental students to have a solid understanding of rhythmic structures and basic music knowledge. 相似文献
20.
In the developing phase of typhoon formation, the spiral belt partly emerges in satellite cloud images. This research starts from images and moves on to graphics and then to representation and recognition. Following this route, local spiral cloud belt is segmented from the raw images using image segmentation, the spiral information is extracted using mathematic morphology, and local spiral curves are detected using Hough transformation. The problem of center locating of developing typhoon has finally been solved through a search algorithm of spiral curve. For No. 99082008 cloud image, the result produced by the algorithm in this paper is at 122. 3 degree west longitude, 17.5 degree north latitude. The real typhoon center location was at 122.4 degree west longitude, 18 degree north latitude. 相似文献