全文获取类型
收费全文 | 20334篇 |
免费 | 2398篇 |
国内免费 | 5篇 |
学科分类
生物科学 | 22737篇 |
出版年
2022年 | 123篇 |
2021年 | 266篇 |
2020年 | 162篇 |
2019年 | 194篇 |
2018年 | 245篇 |
2017年 | 224篇 |
2016年 | 394篇 |
2015年 | 552篇 |
2014年 | 689篇 |
2013年 | 863篇 |
2012年 | 1166篇 |
2011年 | 1139篇 |
2010年 | 709篇 |
2009年 | 683篇 |
2008年 | 1003篇 |
2007年 | 1025篇 |
2006年 | 948篇 |
2005年 | 914篇 |
2004年 | 923篇 |
2003年 | 866篇 |
2002年 | 828篇 |
2001年 | 426篇 |
2000年 | 394篇 |
1999年 | 378篇 |
1998年 | 287篇 |
1997年 | 245篇 |
1996年 | 234篇 |
1995年 | 232篇 |
1994年 | 250篇 |
1993年 | 233篇 |
1992年 | 332篇 |
1991年 | 287篇 |
1990年 | 295篇 |
1989年 | 304篇 |
1988年 | 428篇 |
1987年 | 291篇 |
1986年 | 232篇 |
1985年 | 248篇 |
1984年 | 229篇 |
1983年 | 222篇 |
1982年 | 194篇 |
1981年 | 181篇 |
1980年 | 185篇 |
1979年 | 177篇 |
1978年 | 167篇 |
1977年 | 172篇 |
1976年 | 148篇 |
1975年 | 127篇 |
1974年 | 158篇 |
1973年 | 143篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
Douglas E. Soltis 《Biochemical Systematics and Ecology》1980,8(2):149-151
Sullivantia species were found to produce quercetin 3-O-glycosides, several of which contain glucuronic acid, as well as pedalitin (6-hydroxy-7-O-methyl luteolin), pedalitin 6-O-glycosides, and small amounts of luteolin. Sullivantia has a unique combination of compounds that distinguishes it from other genera in the Saxifraginae for which flavonoid data are available. The nature of the flavonoid compounds is in accordance with a general trend within the Saxifragaceae of reduction and replacement of flavonols by flavones. 相似文献
5.
6.
J M Katz W G Laver D O White E M Anders 《Journal of immunology (Baltimore, Md. : 1950)》1985,134(1):616-622
The recognition of influenza virus hemagglutinin (HA) by T lymphocytes was examined by assaying the T cell proliferative response of influenza virus-primed T cells to purified HA of different influenza A subtypes or to isolated heavy (HA1) or light (HA2) polypeptide chains of the HA molecule. The proliferative response to HA was dependent on the activation of an Ly-1+2- subset of T cells and required the presence of nylon wool-adherent, radiation-resistant accessory cells. T cells from mice primed by infection with one strain of type A influenza virus cross-reacted with other purified HA not only of the same subtype as the priming virus but also of serologically distinct subtypes of influenza A (but not B) virus. The response of virus-primed T cells to the homologous HA or to HA of the same subtype was shown to involve recognition of determinants on both the HA1 and the HA2 chains. The recognition of HA of different subtype by cross-reactive T cells appeared to be directed predominantly to determinants on HA2. Because the antibody response to influenza virus HA is not cross-reactive between subtypes and is directed predominantly to determinants on HA1, the present results indicate that at least some of the determinants on HA recognized by T cells are different from those recognized by B cells and that the HA2 chain may be involved primarily in stimulation of T cell rather than B cell immunity. 相似文献
7.
Simon D X Chuong Robert T Mullen Douglas G Muench 《The Journal of biological chemistry》2002,277(4):2419-2429
The control of subcellular mRNA localization and translation is often mediated by protein factors that are directly or indirectly associated with the cytoskeleton. We report the identification and characterization of a rice seed protein that possesses both RNA and microtubule binding activities. In vitro UV cross-linking assays indicated that this protein binds to all mRNA sequences tested, although there was evidence for preferential binding to RNAs that contained A-C nucleotide sequence motifs. The protein was purified to homogeneity using a two-step procedure, and amino acid sequencing identified it as the multifunctional protein (MFP), a peroxisomal enzyme known to possess a number of activities involved in the beta-oxidation of fatty acids. The recombinant version of this rice MFP binds to RNA in UV cross-linking and gel mobility shift experiments, co-sediments specifically with microtubules, and possesses at least two enzymatic activities involved in peroxisomal fatty acid beta-oxidation. Taken together these data suggest that MFP has an important role in mRNA physiology in the cytoplasm, perhaps in regulating the localization or translation of mRNAs through an interaction with microtubules, in addition to its peroxisomal function. 相似文献
8.
9.
Pollution of freshwater and estuaries 总被引:1,自引:1,他引:0
10.