全文获取类型
收费全文 | 185544篇 |
免费 | 8870篇 |
国内免费 | 923篇 |
专业分类
195337篇 |
出版年
2023年 | 360篇 |
2022年 | 808篇 |
2021年 | 1663篇 |
2020年 | 946篇 |
2019年 | 1247篇 |
2018年 | 13046篇 |
2017年 | 11746篇 |
2016年 | 9496篇 |
2015年 | 4452篇 |
2014年 | 4667篇 |
2013年 | 5540篇 |
2012年 | 11174篇 |
2011年 | 19288篇 |
2010年 | 15969篇 |
2009年 | 12104篇 |
2008年 | 15241篇 |
2007年 | 16780篇 |
2006年 | 5737篇 |
2005年 | 5808篇 |
2004年 | 6055篇 |
2003年 | 5923篇 |
2002年 | 5391篇 |
2001年 | 1211篇 |
2000年 | 881篇 |
1999年 | 1026篇 |
1998年 | 1315篇 |
1997年 | 910篇 |
1996年 | 828篇 |
1995年 | 770篇 |
1994年 | 663篇 |
1993年 | 767篇 |
1992年 | 686篇 |
1991年 | 601篇 |
1990年 | 573篇 |
1989年 | 556篇 |
1988年 | 529篇 |
1987年 | 489篇 |
1986年 | 442篇 |
1985年 | 617篇 |
1984年 | 692篇 |
1983年 | 641篇 |
1982年 | 731篇 |
1981年 | 659篇 |
1980年 | 664篇 |
1979年 | 393篇 |
1978年 | 465篇 |
1977年 | 401篇 |
1976年 | 400篇 |
1972年 | 458篇 |
1971年 | 463篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
102.
David Bellamy 《BMJ (Clinical research ed.)》1983,286(6375):1439-1440
103.
104.
105.
106.
Pawan K. Dhar 《Journal of biosciences》2007,32(1):1005-1008
Systems biology is an approach to explain the behaviour of a system in relation to its individual components. Synthetic biology uses key hierarchical and modular concepts of systems biology to engineer novel biological systems. In my opinion the next step in biology is to use molecule-to-phenotype data using these approaches and integrate them in the form a periodic table. A periodic table in biology would provide chassis to classify, systematize and compare diversity of component properties vis-a-vis system behaviour. Using periodic table it could be possible to compute higher-level interactions from component properties. This paper examines the concept of building a bio-periodic table using protein fold as the fundamental unit. 相似文献
107.
Ferruh Aşçi 《Biologia》2009,64(6):1146-1149
In this study, the structural characteristics, unique features, various organ measurements of males and females of the water
mite Atractides (Atractides) turcicus sp. n. from Turkey are described. In addition, the study compares their characteristics with related species. 相似文献
108.
109.
David C. Margolies 《Experimental & applied acarology》1993,17(6):461-471
Banks grass mites, Oligonychus pratensis (Banks), exhibit a behavior that facilitates their dispersal as aerial plankton over long distances. The propensity to display this behavior and its latency varies among individual mites. Some of this variation can be attributed to genetic differences among individuals. Mother-daughter resemblance and bi-directional selection were used to estimate the genetic component of latency of the aerial dispersal behavior in a wild population collected from corn plants. Mother-daughter regression analysis suggested that up to 10% of variation in initiation of aerial dispersal behavior was attributable to an additive genetic component. Subsequent selection for shorter and longer latency resulted in significant divergence between selected lines after 9 generation, but the response was not symmetrical. Realized heritability for shorter latency was 0.09, while that for longer latency was not different from 0. This response to selection was consistent with results of the mother-daughter analysis, and the response asymmetry may explain the high variability in the mother-daughter regression. In both their natural habitat and in a corn agroecosystem, mites survive by using a succession of temporarily available hosts. Aerial dispersal behavior by Banks grass mites facilitates colonization of new hosts. The genetic basis and selection response of behavior initiating aerial dispersal is consistent with its role in mites population dynamics in this setting. 相似文献
110.