全文获取类型
收费全文 | 4340篇 |
免费 | 299篇 |
国内免费 | 1篇 |
出版年
2023年 | 28篇 |
2022年 | 55篇 |
2021年 | 91篇 |
2020年 | 63篇 |
2019年 | 66篇 |
2018年 | 113篇 |
2017年 | 86篇 |
2016年 | 137篇 |
2015年 | 199篇 |
2014年 | 233篇 |
2013年 | 345篇 |
2012年 | 368篇 |
2011年 | 343篇 |
2010年 | 225篇 |
2009年 | 193篇 |
2008年 | 253篇 |
2007年 | 266篇 |
2006年 | 255篇 |
2005年 | 228篇 |
2004年 | 219篇 |
2003年 | 194篇 |
2002年 | 169篇 |
2001年 | 45篇 |
2000年 | 36篇 |
1999年 | 29篇 |
1998年 | 38篇 |
1997年 | 27篇 |
1996年 | 15篇 |
1994年 | 12篇 |
1993年 | 13篇 |
1992年 | 19篇 |
1991年 | 16篇 |
1990年 | 13篇 |
1989年 | 11篇 |
1988年 | 13篇 |
1987年 | 10篇 |
1986年 | 12篇 |
1985年 | 15篇 |
1984年 | 16篇 |
1983年 | 10篇 |
1981年 | 13篇 |
1980年 | 13篇 |
1979年 | 12篇 |
1978年 | 9篇 |
1976年 | 8篇 |
1975年 | 11篇 |
1974年 | 13篇 |
1973年 | 15篇 |
1972年 | 11篇 |
1969年 | 8篇 |
排序方式: 共有4640条查询结果,搜索用时 15 毫秒
1.
Shull A. Franklin und Ladoff Sonia 《Molecular & general genetics : MGG》1918,19(1-2):110-115
2.
Legionella pneumophila in Cooling Towers: Fluctuations in Counts, Determination of Genetic Variability by Pulsed-Field Gel Electrophoresis (PFGE), and Persistence of PFGE Patterns 下载免费PDF全文
Sonia Ragull Marian Garcia-Nuez Maria Luisa Pedro-Botet Nieves Sopena Maria Esteve Rafael Montenegro Miquel Sabri 《Applied microbiology》2007,73(16):5382-5384
The concentrations of Legionella pneumophila in cooling towers may vary considerably over short periods of time, producing significant fluctuations throughout the year. Despite genetic variability, in small geographical areas the same indistinguishable pulsed-field gel electrophoresis patterns may be shared among different cooling towers and persist over time. 相似文献
3.
Sonia Coni Silvia Maria Serrao Zuleyha Nihan Yurtsever Laura Di Magno Rosa Bordone Camilla Bertani Valerio Licursi Zaira Ianniello Paola Infante Marta Moretti Marialaura Petroni Francesca Guerrieri Alessandro Fatica Alberto Macone Enrico De Smaele Lucia Di Marcotullio Giuseppe Giannini Marella Maroder Enzo Agostinelli Gianluca Canettieri 《Cell death & disease》2020,11(12)
4.
5.
The morphological changes in the gill chloride cells of the armored catfish, Hypostomus tietensis , were investigated after 15 days' exposure to either distilled or hard water. The thickness of the water–blood barrier in the lamellae increased significantly in fish kept in distilled water due to the high proliferation of chloride cells. The apical surface of about 68% of chloride cells was sharply reduced by the development of an apical crypt with a sponge-like surface, although no change in the chloride cell fractional area was found. In contrast, H. tietensis kept in Na+ , Cl− and Ca2+ rich water displayed no significant changes in the number of chloride cells or in their apical surface morphology compared with the control fish. Chloride cell response to ion challenge in H. tietensis suggested the involvement of different strategies to maintain homeostasis in ion-poor water, which may be related to the life history of species. 相似文献
6.
7.
Pyruvate kinase levels were monitored in Neurospora crassa mycelium (grown on different carbon sources for varying time intervals) by immunoprecipitation using polyclonal antibodies raised against a purified enzyme preparation. Pyruvate kinase specific mRNA was demonstrated by hybridization of Northern and dot blots of total RNA with a N. crassa pyruvate kinase gene fragment. Two pyruvate kinase specific mRNA species were detected in mycelia of all ages examined. An age-dependent and carbon source dependent variation in the pyruvate kinase protein and mRNA levels was encountered: both registered an increase for up to about 20 h and a subsequent decline; growth on acetate and sucrose resulted in significantly higher yields of both, relative to that on medium containing ethanol and alanine. Stress caused by heat shock depressed the pyruvate kinase mRNA levels. 相似文献
8.
9.
Cholesterol binding reserve of hyperlipemic rat serum lipoproteins in chronic ethanol administration
Chronic administration of ethanol in rats caused the reduction of serum cholesterol binding reserve. The very low density
and high density lipoproteins, main serum cholesterol binding reserves, were slightly increased with corresponding increases
in their lipid and protein components during initial stage of alcohol consumption. However, these capacities get deminished
during reversal of hyperlipemia induced by prolonged action of ethanol. This situation may be an early indicator for the initiation
of hepatic damage and a variety of secondary effects of ethanol. 相似文献
10.
SV40 immortalizes myogenic cells: DNA synthesis and mitosis in differentiating myotubes 总被引:8,自引:0,他引:8
Sonia Lujvidin Ora Fuchs Uri Nudel David Yaffe 《Differentiation; research in biological diversity》1990,43(3):192-203
Primary skeletal muscle myoblasts have a limited proliferative capacity in cell culture and cease to proliferate after several passages. We examined the effects of several oncogenes on the immortalization and differentiation of primary cultures of rat skeletal muscle myoblasts. Retroviruses containing a SV40 large T antigen (LT) gene very efficiently immortalize myogenic cells. The immortalized cell lines retain a very high differentiation capacity and form, in the appropriate culture conditions, a very dense network of muscle fibers. As in primary culture, cell fusion is associated with the synthesis of large amounts of muscle-specific proteins. However, unlike normal myoblasts (and previously established myogenic cell lines), nuclei in the multinucleated fibers of SV40-immortalized cells synthesize DNA and enter mitosis. Thus, withdrawal from DNA synthesis is not obligatory for cell fusion and biochemical differentiation. Using a retrovirus coding for a temperature-sensitive SV40 LT, myogenic cell lines were produced in which the SV40 LT could be inactivated by a shift from 33 degrees C to 39 degrees C. The inactivation of LT induced massive cell fusion and synthesis of muscle proteins. The nuclei in those fibers did not synthesize DNA, nor did they undergo mitosis. This approach enabled the reproducible establishment of myogenic cell lines from very small populations of myoblasts or single primary myogenic clones. Activated p53 also readily immortalized cells in primary muscle cultures, however the cells of eight out of the nine cell lines isolated had a fibroblastic morphology and could not be induced to form multinucleated fibers. 相似文献