全文获取类型
收费全文 | 10324篇 |
免费 | 1033篇 |
国内免费 | 785篇 |
出版年
2023年 | 143篇 |
2022年 | 153篇 |
2021年 | 545篇 |
2020年 | 405篇 |
2019年 | 457篇 |
2018年 | 437篇 |
2017年 | 318篇 |
2016年 | 450篇 |
2015年 | 651篇 |
2014年 | 815篇 |
2013年 | 795篇 |
2012年 | 985篇 |
2011年 | 833篇 |
2010年 | 564篇 |
2009年 | 461篇 |
2008年 | 499篇 |
2007年 | 529篇 |
2006年 | 430篇 |
2005年 | 359篇 |
2004年 | 325篇 |
2003年 | 257篇 |
2002年 | 218篇 |
2001年 | 185篇 |
2000年 | 163篇 |
1999年 | 161篇 |
1998年 | 74篇 |
1997年 | 76篇 |
1996年 | 77篇 |
1995年 | 56篇 |
1994年 | 70篇 |
1993年 | 56篇 |
1992年 | 87篇 |
1991年 | 66篇 |
1990年 | 53篇 |
1989年 | 58篇 |
1988年 | 44篇 |
1987年 | 43篇 |
1986年 | 35篇 |
1985年 | 40篇 |
1984年 | 15篇 |
1983年 | 20篇 |
1981年 | 6篇 |
1980年 | 10篇 |
1979年 | 18篇 |
1978年 | 10篇 |
1976年 | 9篇 |
1975年 | 6篇 |
1974年 | 8篇 |
1970年 | 11篇 |
1968年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
1.
2.
3.
4.
Ye. P. Dulepova V. A. Nadtochii L. L. Budnikova 《Russian Journal of Marine Biology》2008,34(7):472-481
The trophic structure of benthic communities in the Sea of Okhotsk and Bering Sea was analyzed based on the results of macrobenthic
survey catches conducted in the Far Eastern seas in the 2000s. The production of trophic levels and entire communities was
determined. It was shown that production of benthic communities is still at a high level and has almost not changed since
the 1980s. The arrangement of the communities of some shelf areas by productivity characteristics was made. 相似文献
5.
Weilan Ye 《The EMBO journal》2014,33(8):786-787
Since metastatic lesions of solid tumors are the major cause of mortality in cancer patients, understanding the molecular mechanisms of metastasis is of paramount importance. Although extensive knowledge has been accumulated regarding the early steps in metastasis—starting with the departure of cancer cells from their primary sites, to their transit through the hematogenous and/or lymphatic systems, and ending with their entrance into the parenchyma of distant organs—it is difficult if not impossible to translate such knowledge into medicine due to the challenge of identifying patients with only primary tumors but otherwise pristine organs. In other words, autopsy studies indicate that a large proportion of patients already harbor dormant, undetectable micrometastases at the time of cancer diagnosis (Hensel et al, 2013 ). Accordingly, stopping tumor cell dissemination is too late for these patients. Therefore, understanding the survival and outgrowth of micrometastases may hold greater promise to combat metastatic disease. 相似文献
6.
Yang Su-Rong Sun Huan-Xin Hu Zhen-Zhen Wang Si-Heng Sun Hui Xue Yin-Jia Ye Chen-Bo 《Sleep and biological rhythms》2017,15(1):57-65
Sleep and Biological Rhythms - Chronic sleep deprivation (SD) is an overwhelming problem in young students. Firstly, we investigated whether different levels of pre-training SD had effects on... 相似文献
7.
8.
Herein, we describe a case study into the population dynamics of in vitro selection, using RNA-cleaving DNAzymes as a model system. We sought to understand how the composition of the population can change over time in response to different levels of selection pressure, and how well these changes are correlated with selection of the target phenotype. The model population is composed of 857 DNAzyme clones representing 215 discrete sequence classes, which had previously been identified from two parallel selection experiments, conducted under an increasingly stringent, or permissive and constant selection time pressure. In this report, we determined the principal phenotypic properties (i.e. kobs, maximum cleavage yield and PCR efficiency) from a sample of 58 clones representing 46 different major and minor sequence classes from various rounds of each selection experiment. Interestingly, a positive correlation between the catalytic rate constant and the corresponding frequency and temporal position of a given DNAzyme was not consistently observed; however, the strength of the correlation was qualitatively higher under conditions of more stringent selection time pressure. These results suggest that the selective sampling paradigm on which in vitro selection is based, may underestimate the true functional capacity of any given random-sequence library. 相似文献
9.
10.