全文获取类型
收费全文 | 251篇 |
免费 | 11篇 |
国内免费 | 20篇 |
专业分类
282篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 6篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 10篇 |
2018年 | 6篇 |
2017年 | 6篇 |
2016年 | 6篇 |
2015年 | 13篇 |
2014年 | 12篇 |
2013年 | 20篇 |
2012年 | 10篇 |
2011年 | 3篇 |
2010年 | 9篇 |
2009年 | 13篇 |
2008年 | 9篇 |
2007年 | 12篇 |
2006年 | 14篇 |
2005年 | 11篇 |
2004年 | 4篇 |
2003年 | 9篇 |
2002年 | 6篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 7篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1973年 | 1篇 |
排序方式: 共有282条查询结果,搜索用时 15 毫秒
91.
Prey refuges are expected to affect population dynamics, but direct experimental tests of this hypothesis are scarce. Larvae of western flower thrips Frankliniella occidentalis use the web produced by spider mites as a refuge from predation by the predatory mite Neoseiulus cucumeris. Thrips incur a cost of using the refuge through reduced food quality within the web due to spider mite herbivory, resulting in a reduction of thrips developmental rate. These individual costs and benefits of refuge use were incorporated in a stage-structured predator-prey model developed for this system. The model predicted higher thrips numbers in presence than in absence of the refuge during the initial phase. A greenhouse experiment was carried out to test this prediction: the dynamics of thrips and their predators was followed on plants damaged by spider mites, either with or without web. Thrips densities in presence of predators were higher on plants with web than on unwebbed plants after 3 weeks. Experimental data fitted model predictions, indicating that individual-level measurements of refuge costs and benefits can be extrapolated to the level of interacting populations. Model-derived calculations of thrips population growth rate enable the estimation of the minimum predator density at which thrips benefit from using the web as a refuge. The model also predicted a minor effect of the refuge on the prey density at equilibrium, indicating that the effect of refuges on population dynamics hinges on the temporal scale considered. 相似文献
92.
93.
Translation is a key process for gene expression. Timely identification of the translation initiation site (TIS) is very important for conducting in-depth genome analysis. With the avalanche of genome sequences generated in the postgenomic age, it is highly desirable to develop automated methods for rapidly and effectively identifying TIS. Although some computational methods were proposed in this regard, none of them considered the global or long-range sequence-order effects of DNA, and hence their prediction quality was limited. To count this kind of effects, a new predictor, called “iTIS-PseTNC,” was developed by incorporating the physicochemical properties into the pseudo trinucleotide composition, quite similar to the PseAAC (pseudo amino acid composition) approach widely used in computational proteomics. It was observed by the rigorous cross-validation test on the benchmark dataset that the overall success rate achieved by the new predictor in identifying TIS locations was over 97%. As a web server, iTIS-PseTNC is freely accessible at http://lin.uestc.edu.cn/server/iTIS-PseTNC. To maximize the convenience of the vast majority of experimental scientists, a step-by-step guide is provided on how to use the web server to obtain the desired results without the need to go through detailed mathematical equations, which are presented in this paper just for the integrity of the new prection method. 相似文献
94.
95.
Fabiano Cordeiro Moreira Bruno Dustan Igor G Hamoy André M Ribeiro-dos-Santos ?ndrea Ribeiro dos Santos 《Bioinformation》2014,10(9):602-605
MicroRNAs (miRNAs) are small non-coding nucleotide sequences between 17 and 25 nucleotides in length that primarily function
in the regulation of gene expression. A since miRNA has thousand of predict targets in a complex, regulatory cell signaling
network. Therefore, it is of interest to study multiple target genes simultaneously. Hence, we describe a web tool (developed using
Java programming language and MySQL database server) to analyse multiple targets of pre-selected miRNAs. We cross validated
the tool in eight most highly expressed miRNAs in the antrum region of stomach. This helped to identify 43 potential genes that are
target of at least six of the referred miRNAs. The developed tool aims to reduce the randomness and increase the chance of
selecting strong candidate target genes and miRNAs responsible for playing important roles in the studied tissue.
Availability
http://lghm.ufpa.br/targetcompare 相似文献96.
feedr and animalnexus.ca: A paired R package and user‐friendly Web application for transforming and visualizing animal movement data from static stations 下载免费PDF全文
Stefanie E. LaZerte Matthew W. Reudink Ken A. Otter Jackson Kusack Jacob M. Bailey Austin Woolverton Mark Paetkau Adriaan de Jong David J. Hill 《Ecology and evolution》2017,7(19):7884-7896
Radio frequency identification (RFID) provides a simple and inexpensive approach for examining the movements of tagged animals, which can provide information on species behavior and ecology, such as habitat/resource use and social interactions. In addition, tracking animal movements is appealing to naturalists, citizen scientists, and the general public and thus represents a tool for public engagement in science and science education. Although a useful tool, the large amount of data collected using RFID may quickly become overwhelming. Here, we present an R package (feedr) we have developed for loading, transforming, and visualizing time‐stamped, georeferenced data, such as RFID data collected from static logger stations. Using our package, data can be transformed from raw RFID data to visits, presence (regular detections by a logger over time), movements between loggers, displacements, and activity patterns. In addition, we provide several conversion functions to allow users to format data for use in functions from other complementary R packages. Data can also be visualized through static or interactive maps or as animations over time. To increase accessibility, data can be transformed and visualized either through R directly, or through the companion site: http://animalnexus.ca , an online, user‐friendly, R‐based Shiny Web application. This system can be used by professional and citizen scientists alike to view and study animal movements. We have designed this package to be flexible and to be able to handle data collected from other stationary sources (e.g., hair traps, static very high frequency (VHF) telemetry loggers, observations of marked individuals in colonies or staging sites), and we hope this framework will become a meeting point for science, education, and community awareness of the movements of animals. We aim to inspire citizen engagement while simultaneously enabling robust scientific analysis. 相似文献
97.
98.
利用文献计量学方法,统计分析了1995—2007年11月Web of Science收录的生物信息学(bioinformatics)研究文献,探讨了生物信息学文献研究的年代分布、语种、期刊分布、作者、文献类型、主题分布以及发文量前10名的国家和机构,以期了解世界各国在这一研究领域的进展情况。 相似文献
99.
Yang S Wang H Yang Y Wang W Jiang J Zhao X Du Q Wang X Yao Y Shen H Shen C Zhao Y 《Gene》2012,498(2):311-316
Background
Advanced glycation end products (AGEs) are produced by non-enzymatic glycation or glycoxidation of proteins, lipids and nucleic acids. The bond of AGEs and the receptor of AGE (AGER) in a pro-oxidant environment could induce immune and inflammation reaction involved in progress of microvascular disease. Accumulated evidence warrant further study on AGE–AGER pathway and genetic susceptibility to hypertension (HT).Methods
We designed a two-stage association study to evaluate the association of AGER polymorphism and HT. In stage 1, seven tagSNPs were tested in 524 cases and 531 controls and the significant SNPs (P < 0.05) would enter into stage 2 including 807 cases and 869 controls. Furthermore, joint analysis was performed for all 2731 subjects including 1331 cases and 1400 controls, and meta-analysis was applied to evaluate combined estimations from the subgroups of stage 1 and stage 2.Results
In stage 1, rs204994 had significant association with HT (P < 0.05) and enter stage 2. Neither joint analysis nor meta-analysis found statistical association of rs204994 with HT after adjusted for the covariates in the whole population. However, further stratification analysis found that rs204994 was significantly associated with HT in < 50 years and ≥ 50 years groups, ORs (95%CI) of dominant model were 1.623 (1.054–2.500) and 0.721 (0.546–0.952) respectively. No significant correlation was found between blood pressure and the polymorphisms of rs204994.Conclusions
Our data suggests that age might modulate the genetic effects of variation of rs204994 in AGER on HT and further replications in other populations and functional studies should be warranted. 相似文献100.