首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   13篇
  免费   1篇
教育   4篇
科学研究   10篇
  2020年   1篇
  2018年   4篇
  2017年   1篇
  2015年   4篇
  2011年   1篇
  2005年   1篇
  2002年   1篇
  2000年   1篇
排序方式: 共有14条查询结果,搜索用时 265 毫秒
1.
Snow leopard     
Snow leopard, an elusive mammal species of the cat family, is the top-predator of the Central and South Asian, high-altitude ecosystem. Snow leopards occur at low densities across the Central Asian mountains and the Indian Himalayan region. Owing to their secretive nature and inaccessible habitat, little is known about its ecology and distribution. Due to its endangered status and high aesthetic value, the snow leopard is considered as an ‘umbrella species’ for wildlife conservation in the Indian Himalayas. This article summarizes the current knowledge on snow leopard ecology and conservation issues in the Indian context.  相似文献   
2.
We present design, characterization, and testing of an inexpensive, sheath-flow based microfluidic device for three-dimensional (3D) hydrodynamic focusing of cells in imaging flow cytometry. In contrast to other 3D sheathing devices, our device hydrodynamically focuses the cells in a single-file near the bottom wall of the microchannel that allows imaging cells with high magnification and low working distance objectives, without the need for small device dimensions. The relatively large dimensions of the microchannels enable easy fabrication using less-precise fabrication techniques, and the simplicity of the device design avoids the need for tedious alignment of various layers. We have characterized the performance of the device with 3D numerical simulations and validated these simulations with experiments of hydrodynamic focusing of a fluorescently dyed sample fluid. The simulations show that the width and the height of the 3D focused sample stream can be controlled independently by varying the heights of main and side channels of the device, and the flow rates of sample and sheath fluids. Based on simulations, we also provide useful guidelines for choosing the device dimensions and flow rates for focusing cells of a particular size. Thereafter, we demonstrate the applicability of our device for imaging a large number of RBCs using brightfield microscopy. We also discuss the choice of the region of interest and camera frame rate so as to image each cell individually in our device. The design of our microfluidic device makes it equally applicable for imaging cells of different sizes using various other imaging techniques such as phase-contrast and fluorescence microscopy.  相似文献   
3.
Our objectives for this article are twofold: first, to examine the convergence of nations with regard to ICT access; and second, to see whether countries in the same continental region (South and East Asia, West and Middle East Asia, Africa, Eastern Europe, Western Europe, North America, South America, and Oceania) or having same initial ICT access have coalesced into groups. We constructed an ICT access index using three indicators (mobile phone, Internet, and broadband use per 100 population) for a sample of 198 nations for the 16-year period from 2000 to 2015. Results show that digital divide has declined in relative terms, but not in absolute terms. The countries, starting at lower ICT levels, are not adopting ICT faster than the leaders. Continental region-wise analysis also shows that the catch-up is maximum for already developed countries, and minimum for countries in African and Oceania continental regions.  相似文献   
4.
The problem of pesticides is not new and its exposure to human due to indiscriminate use is largely associated with the health related problems including neurotoxicological alterations. High levels of pesticide residues and their metabolites in the dietary constituents, food materials, maternal blood, cord blood, placenta breast milk have been reported and linked to alterations in birth weight, crown heel length, head circumference, mid-arm circumference and ponderal index of the neonates. Epidemiological studies have suggested that exposure of pesticide to human could be a significant risk factor for neurological disorders, including Parkinson’s disease, Alzheimer’s disease and multiple sclerosis. Cholinergic and non-cholinergic dysfunctions in pesticide exposed population, especially in children have also been frequently reported in recent years. Developmental neurotoxicity is another concern in the area where pregnant are more prone towards its exposure and which results in the abnormalities in the fetus. In view of the increasing risk of human health through pesticide exposure, the present review has been focused on the studies pertaining to pesticide induced neurochemical alterations and associated behavioral abnormalities in farm workers which could establish a possible link between the its exposure and associated health hazards.  相似文献   
5.
To refine the theories of operations strategy, we need research from all different situational contexts, including different countries—both developing and developed. There have been many studies, including some replications, done in various parts of the world to further the debate on whether competitive priorities are mutually supportive or if they present potential trade-offs, but hardly any from a rapidly growing economy, such as India. This study is a significant attempt in that direction. After a thorough review of the literature, a set of hypotheses is introduced to test whether Indian manufacturers view competitive priorities as mutually supportive or trade-offs. The data from over 150 high-ranking individuals from over 75 manufacturers in India is used to test the hypotheses by way of cluster analysis and ANOVA. The resultant taxonomy reveals patterns that uniquely represent Indian manufacturers' view of the competitive priorities, namely quality, flexibility, delivery and price. The study findings have significant managerial implications, both for India and other developing as well as developed economies. The taxonomy will serve to gauge India's manufacturers' role in the world. From a researcher's perspective, this study makes a significant contribution to theory development, furthers our understanding of the strategic role of operations, moves forward the ongoing debate on the topic of trade-offs or complementarity, and paves the way for future studies in this topical area.  相似文献   
6.
Statistics can help us to make predictions. An interesting example regarding the football world cup explores the rankings to suggest the group(s) of death in the ensuing world cup.  相似文献   
7.
Low back pain is very disabling and dispiriting because of the physical impediment it causes and its psychological effects. Innumerable factors have been implicated in its etiology. In spite of improvements in diagnostic modalities, a considerable number of such cases fall in the ambiguous zone of unknown etiology or ‘idiopathic.’Early diagnosis of low back pain will allow effective prevention and treatment to be offered. This study was conducted to assess the contribution of vitamin D levels and other biochemical factors to chronic low back pain in such cases. All patients attending the orthopedics OPD for low back pain in whom a precise anatomical cause could not be localized, were prospectively enrolled in this study. We measured serum levels of glucose, calcium, phosphorus, uric acid, rheumatoid factor, C reactive protein, alkaline phosphatase, total protein, albumin and 25 (OH) D concentrations in 200 cases and 200 control samples. The patients showed significantly lower vitamin D levels compared to controls with p value < 0.0001. The maximum number of low back pain patients were in the age group of 31–50 years (42 %).The average BMI was 23.27 ± 5.17 kg/sq m, 73 % of total patient population were females and 27 % were known case of type 2 diabetes mellitus. Calcium, alkaline phosphatase, was positively correlated with vitamin D and glucose showed a negative correlation with vitamin D in the patient population. The problem of low back pain provides a challenge to health care providers. The problem in developing countries is compounded by ignorance to report for early treatment and occupational compulsions in rural areas and sedentary lifestyle in urban youth. The authors strongly recommend early frequent screening for vitamin D along with glucose, protein, albumin, calcium, phosphorus, CRP as part of general health checkup for non-specific body pain, especially low back pain.  相似文献   
8.
Nanoscale synthetic biology can benefit from programmable nanoliter-scale processing of DNA in microfluidic chips if they are interfaced effectively to biochemical arrays such as microwell plates. Whereas active microvalve chips require complex fabrication and operation, we show here how a passive and readily fabricated microchip can be employed for customizable nanoliter scale pipetting and reaction control involving DNA. This recently developed passive microfluidic device, supporting nanoliter scale combinatorial droplet generation and mixing, is here used to generate a DNA test library with one member per droplet exported to addressed locations on microwell plates. Standard DNA assembly techniques, such as Gibson assembly, compatible with isothermal on-chip operation, are employed and checked using off-chip PCR and assembly PCR. The control of output droplet sequences and mixing performance was verified using dyes and fluorescently labeled DNA solutions, both on-chip and in external capillary channels. Gel electrophoresis of products and DNA sequencing were employed to further verify controlled combination and functional enzymatic assembly. The scalability of the results to larger DNA libraries is also addressed by combinatorial input expansion using sequential injection plugs from a multiwell plate. Hence, the paper establishes a proof of principle of the production of functional combinatorial mixtures at the nanoliter scale for one sequence per well DNA libraries.  相似文献   
9.
We here present and characterize a programmable nanoliter scale droplet-on-demand device that can be used separately or readily integrated into low cost single layer rapid prototyping microfluidic systems for a wide range of user applications. The passive microfluidic device allows external (off-the-shelf) electronically controlled pinch valves to program the delivery of nanoliter scale aqueous droplets from up to 9 different inputs to a central outlet channel. The inputs can be either continuous aqueous fluid streams or microliter scale aqueous plugs embedded in a carrier fluid, in which case the number of effective input solutions that can be employed in an experiment is no longer strongly constrained (100 s–1000 s). Both nanoliter droplet sequencing output and nanoliter-scale droplet mixing are reported with this device. Optimization of the geometry and pressure relationships in the device was achieved in several hardware iterations with the support of open source microfluidic simulation software and equivalent circuit models. The requisite modular control of pressure relationships within the device is accomplished using hydrodynamic barriers and matched resistance channels with three different channel heights, custom parallel reversible microfluidic I/O connections, low dead-volume pinch valves, and a simply adjustable array of external screw valves. Programmable sequences of droplet mixes or chains of droplets can be achieved with the device at low Hz frequencies, limited by device elasticity, and could be further enhanced by valve integration. The chip has already found use in the characterization of droplet bunching during export and the synthesis of a DNA library.  相似文献   
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号