全文获取类型
收费全文 | 33430篇 |
免费 | 2963篇 |
国内免费 | 24篇 |
专业分类
36417篇 |
出版年
2023年 | 174篇 |
2022年 | 396篇 |
2021年 | 806篇 |
2020年 | 437篇 |
2019年 | 569篇 |
2018年 | 677篇 |
2017年 | 559篇 |
2016年 | 1008篇 |
2015年 | 1727篇 |
2014年 | 1818篇 |
2013年 | 2127篇 |
2012年 | 2780篇 |
2011年 | 2835篇 |
2010年 | 1728篇 |
2009年 | 1431篇 |
2008年 | 2109篇 |
2007年 | 2069篇 |
2006年 | 2054篇 |
2005年 | 1746篇 |
2004年 | 1765篇 |
2003年 | 1549篇 |
2002年 | 1507篇 |
2001年 | 336篇 |
2000年 | 268篇 |
1999年 | 318篇 |
1998年 | 315篇 |
1997年 | 234篇 |
1996年 | 210篇 |
1995年 | 180篇 |
1994年 | 163篇 |
1993年 | 155篇 |
1992年 | 138篇 |
1991年 | 172篇 |
1990年 | 115篇 |
1989年 | 115篇 |
1988年 | 108篇 |
1987年 | 84篇 |
1986年 | 113篇 |
1985年 | 115篇 |
1984年 | 111篇 |
1983年 | 108篇 |
1982年 | 119篇 |
1981年 | 116篇 |
1980年 | 97篇 |
1979年 | 70篇 |
1978年 | 60篇 |
1977年 | 51篇 |
1976年 | 61篇 |
1975年 | 61篇 |
1974年 | 52篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
Modulation of the expression of interleukin 2 receptors of human thymocytes by recombinant interleukin 2 总被引:3,自引:0,他引:3
The effect of purified recombinant interleukin 2 on the expression of the receptors for interleukin 2 by human thymocytes was examined. Interleukin 2 augmented the expression of interleukin 2 receptors and interferon-gamma synthesis by thymocytes activated with concanavalin A, and it was required to maintain the growth of thymocytes in vitro and the expression of interleukin 2 receptors. The increase observed in the number of receptor bearing thymocytes and in the density of receptors due to interleukin 2 occurred within the first 2 days of culture. Dexamethasone inhibited the expression of interleukin 2 receptors, the synthesis of interferon-gamma, and the early proliferation and protein synthesis of lectin-activated thymocytes during the first 2 days of culture. The inhibitory effect of dexamethasone on the expression of interleukin 2 receptors and on the synthesis of interferon-gamma was reversed by interleukin 2, whereas its effect on proliferation and on protein synthesis during the first two days of culture was not reversed by interleukin 2. Interleukin 2 induced the proliferation of thymocytes in vitro, even in the absence of activation by lectin; however, the number of cells displaying receptors which could be detected with anti-Tac remained low throughout the first week of culture and interferon-gamma synthesis was not observed. Nonetheless, interleukin 2-induced proliferation was inhibited by anti-Tac on a dose dependent manner. The results of the study document that recombinant interleukin 2, like purified natural interleukin 2, is required for the expression of interleukin 2 receptors, for interferon-gamma synthesis, and for the growth of thymocytes in vitro. 相似文献
3.
4.
Andrew C Smith 《BMJ (Clinical research ed.)》1981,283(6306):1596-1597
5.
Denise Risch Nicholas J. Gales Jason Gedamke Lars Kindermann Douglas P. Nowacek Andrew J. Read Ursula Siebert Ilse C. Van Opzeeland Sofie M. Van Parijs Ari S. Friedlaender 《Biology letters》2014,10(4)
For decades, the bio-duck sound has been recorded in the Southern Ocean, but the animal producing it has remained a mystery. Heard mainly during austral winter in the Southern Ocean, this ubiquitous sound has been recorded in Antarctic waters and contemporaneously off the Australian west coast. Here, we present conclusive evidence that the bio-duck sound is produced by Antarctic minke whales (Balaenoptera bonaerensis). We analysed data from multi-sensor acoustic recording tags that included intense bio-duck sounds as well as singular downsweeps that have previously been attributed to this species. This finding allows the interpretation of a wealth of long-term acoustic recordings for this previously acoustically concealed species, which will improve our understanding of the distribution, abundance and behaviour of Antarctic minke whales. This is critical information for a species that inhabits a difficult to access sea-ice environment that is changing rapidly in some regions and has been the subject of contentious lethal sampling efforts and ongoing international legal action. 相似文献
6.
7.
Andrew Leask 《Journal of cell communication and signaling》2010,4(1):71-72
Connective tissue growth factor (CTGF/CCN2) is overexpressed in diabetes. Diabetic rats possess myocardial and cardiomyocyte
hypertrophy. In a recent report, Wang and colleagues (Am J Physiol Cell Physiol. 2009 Jul 22. [Epub ahead of print]) show
that CCN2 directly mediates cardiomyocyte hypertrophy as well as that induced by high glucose and fatty acid. CCN2 acted via
the TrkA receptor. These data are the subject of this commentary, and emphasize that CCN2 may be an excellent target for therapy
in diabetes. 相似文献
8.
9.
Andrew Bamji 《BMJ (Clinical research ed.)》1987,294(6574):772-773
10.