全文获取类型
收费全文 | 23285篇 |
免费 | 2191篇 |
国内免费 | 11篇 |
出版年
2021年 | 301篇 |
2020年 | 188篇 |
2019年 | 265篇 |
2018年 | 307篇 |
2017年 | 273篇 |
2016年 | 512篇 |
2015年 | 768篇 |
2014年 | 951篇 |
2013年 | 1177篇 |
2012年 | 1437篇 |
2011年 | 1479篇 |
2010年 | 953篇 |
2009年 | 900篇 |
2008年 | 1279篇 |
2007年 | 1319篇 |
2006年 | 1218篇 |
2005年 | 1162篇 |
2004年 | 1143篇 |
2003年 | 1155篇 |
2002年 | 1099篇 |
2001年 | 411篇 |
2000年 | 322篇 |
1999年 | 337篇 |
1998年 | 313篇 |
1997年 | 245篇 |
1996年 | 241篇 |
1995年 | 231篇 |
1994年 | 210篇 |
1993年 | 240篇 |
1992年 | 259篇 |
1991年 | 218篇 |
1990年 | 206篇 |
1989年 | 197篇 |
1988年 | 167篇 |
1987年 | 192篇 |
1986年 | 170篇 |
1985年 | 209篇 |
1984年 | 224篇 |
1983年 | 179篇 |
1982年 | 209篇 |
1981年 | 194篇 |
1980年 | 178篇 |
1979年 | 161篇 |
1978年 | 150篇 |
1977年 | 138篇 |
1976年 | 114篇 |
1975年 | 129篇 |
1974年 | 168篇 |
1973年 | 117篇 |
1972年 | 106篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
1.
Sacramento Doralice Rodrigues Coelho Rosalie Reed Rodrigues Wigg Márcia Dutra Toledo Luna Linhares Luiz Fernando de Matos dos Santos Marta Gonçalves Azevedo Soares Semêdo Luzia Teixeira de Ribeiro da Silva Antonio Jorge 《World journal of microbiology & biotechnology》2004,20(3):225-229
A promising producer of bioactive compounds isolated from a Brazilian tropical soil was tested for its range of antimicrobial
activities. Strain 606, classified as Streptomyces sp., could not be identified up to species level, suggesting a possible new taxon. The supernatant and 10 extracts and fractions,
obtained by extraction and chromatographic techniques, presented antimicrobial activity using antibiograms. The methanolic
fraction was highly active against pathogenic bacteria, phytopathogenic fungi and the human pathogenic yeast Candida albicans. It also possessed high antiviral activity inhibiting the propagation of an acyclovir-resistant herpes simplex virus type
1 strain on HEp-2 cells at non-cytotoxic concentration. The strong cytotoxic effect suggests an antitumour action.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
2.
Scott P. Lawrence Nicholas A. Bright J. Paul Luzio Katherine Bowers 《Molecular biology of the cell》2010,21(20):3540-3551
The pH and lumenal environment of intracellular organelles is considered essential for protein sorting and trafficking through the cell. We provide the first evidence that a mammalian NHE sodium (potassium)/proton exchanger, NHE8, plays a key role in the control of protein trafficking and endosome morphology. At steady state, the majority of epitope-tagged NHE8 was found in the trans-Golgi network of HeLa M-cells, but a proportion was also localized to multivesicular bodies (MVBs). Depletion of NHE8 in HeLa M-cells with siRNA resulted in the perturbation of MVB protein sorting, as shown by an increase in epidermal growth factor degradation. Additionally, NHE8-depleted cells displayed striking perinuclear clustering of endosomes and lysosomes, and there was a ninefold increase in the cellular volume taken up by LAMP1/LBPA-positive, dense MVBs. Our data points to a role for the ion exchange activity of NHE8 being required to maintain endosome morphology, as overexpression of a nonfunctional point mutant protein (NHE8 E225Q) resulted in phenotypes similar to those seen after siRNA depletion of endogenous NHE8. Interestingly, we found that depletion of NHE8, despite its function as a sodium (potassium)/proton antiporter, did not affect the overall pH inside dense MVBs. 相似文献
3.
4.
5.
6.
7.
8.
9.
Internode length in Pisum. I. The effect of the Le/le gene difference on endogenous gibberellin-like substances 总被引:2,自引:0,他引:2
The allelopathic potential of the dry fruits of Washingtonia filifera (L. Linden) H. Wendl. was investigated. Leachates from fruits inhibited the germination of lettuce, wheat, red cabbage and cucumber seeds. The inhibitory effect was partly neutralized by kinetin (20 mg 1−1 ) and gibberellic acid (50 mg 1−1 ). The effect of kinetin was more pronounced at 25°C than at 20°C. Substances inhibiting germination were localized in the pericarp of the fruit and were resistant to high temperature. 相似文献
10.
Myoglobin (Mb) is the classic vertebrate oxygen-binding protein present in aerobic striated muscles. It functions principally in oxygen delivery and provides muscle with its characteristic red colour. Members of the Antarctic icefish family (Channichthyidae) are widely thought to be extraordinary for lacking cardiac Mb expression, a fact that has been attributed to their low metabolic rate and unusual evolutionary history. Here, we report that cardiac Mb deficit, associated with pale heart colour, has evolved repeatedly during teleost evolution. This trait affects both gill- and air-breathing species from temperate to tropical habitats across a full range of salinities. Cardiac Mb deficit results from total pseudogenization in three-spined stickleback and is associated with a massive reduction in mRNA level in two species that evidently retain functional Mb. The results suggest that near or complete absence of Mb-assisted oxygen delivery to heart muscle is a common facet of teleost biodiversity, even affecting lineages with notable oxygen demands. We suggest that Mb deficit may affect how different teleost species deal with increased tissue oxygen demands arising under climate change. 相似文献