全文获取类型
收费全文 | 3769篇 |
免费 | 359篇 |
国内免费 | 3篇 |
出版年
2023年 | 42篇 |
2022年 | 18篇 |
2021年 | 45篇 |
2020年 | 38篇 |
2019年 | 42篇 |
2018年 | 114篇 |
2017年 | 78篇 |
2016年 | 119篇 |
2015年 | 145篇 |
2014年 | 146篇 |
2013年 | 225篇 |
2012年 | 315篇 |
2011年 | 330篇 |
2010年 | 165篇 |
2009年 | 154篇 |
2008年 | 290篇 |
2007年 | 267篇 |
2006年 | 213篇 |
2005年 | 225篇 |
2004年 | 191篇 |
2003年 | 152篇 |
2002年 | 131篇 |
2001年 | 72篇 |
2000年 | 64篇 |
1999年 | 50篇 |
1998年 | 32篇 |
1997年 | 16篇 |
1996年 | 22篇 |
1995年 | 14篇 |
1994年 | 15篇 |
1993年 | 14篇 |
1992年 | 27篇 |
1991年 | 40篇 |
1990年 | 25篇 |
1989年 | 17篇 |
1988年 | 26篇 |
1987年 | 22篇 |
1986年 | 25篇 |
1985年 | 32篇 |
1984年 | 14篇 |
1983年 | 10篇 |
1982年 | 10篇 |
1981年 | 12篇 |
1979年 | 19篇 |
1978年 | 12篇 |
1977年 | 11篇 |
1976年 | 10篇 |
1974年 | 10篇 |
1973年 | 13篇 |
1971年 | 9篇 |
排序方式: 共有4131条查询结果,搜索用时 15 毫秒
71.
Spa32 regulates a switch in substrate specificity of the type III secreton of Shigella flexneri from needle components to Ipa proteins
下载免费PDF全文
![点击此处可从《Journal of bacteriology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Magdalena J Hachani A Chamekh M Jouihri N Gounon P Blocker A Allaoui A 《Journal of bacteriology》2002,184(13):3433-3441
Type III secretion systems (TTSS) are essential virulence determinants of many gram-negative bacteria and serve, upon physical contact with target cells, to translocate bacterial proteins directly across eukaryotic cell membranes. The Shigella TTSS is encoded by the mxi/spa loci located on its virulence plasmid. By electron microscopy secretons are visualized as tripartite with an external needle, a transmembrane domain, and a cytoplasmic bulb. In the present study, we generated a Shigella spa32 mutant and studied its phenotype. The spa32 gene shows low sequence homology to Salmonella TTSS1 invJ/spaN and to flagellar fliK. The spa32 mutant, like the wild-type strain, secreted the Ipas and IpgD, which are normally secreted via the TTSS, at low levels into the growth medium. However, unlike the wild-type strain, the spa32 mutant could neither be induced to secrete the Ipas and IpgD instantaneously upon addition of Congo red nor penetrate HeLa cells in vitro. Additionally, the Spa32 protein is secreted in large amounts by the TTSS during exponential growth but not upon Congo red induction. Interestingly, electron microscopy analysis of the spa32 mutant revealed that the needle of its secretons were up to 10 times longer than those of the wild type. In addition, in the absence of induction, the spa32 mutant secreted normal levels of MxiI but a large excess of MxiH. Taken together, our data indicate that the spa32 mutant presents a novel phenotype and that the primary defect of the mutant may be its inability to regulate or control secretion of MxiH. 相似文献
72.
Cytochemical activity of succinate dehydrogenase (SDG), L-glycerophosphate dehydrogenase (L-GPDG), lactate dehydrogenase (LDG), and glutamate dehydrogenase (GDG) increased immediately after total-body irradiation with a dose of 129 mC/kg. After 2 h, LDG activity only returned to the control level. Irradiation of the head with the same dose caused less pronounced changes. Changes caused by lethal irradiation (1290 mC/kg) were different: there was an increase after exposure of the abdomen and a decrease in the activity of SDG and L-GPDG after irradiation of the head. 相似文献
73.
74.
75.
76.
Malory Randon Christophe Bonenfant Jacques Michallet Thierry Chevrier Carole Toïgo Jean-Michel Gaillard Marion Valeix 《Population Ecology》2020,62(2):244-257
In a context of changing carnivore populations worldwide, it is crucial to understand the consequences of these changes for prey populations. The recolonization by wolves of the French Vercors mountain range and the long-term monitoring (2001–2017) of roe deer in this area provided a unique opportunity to assess the effects of wolves on this prey. Roe deer was the main prey of wolves in the west Vercors mountain range during this recolonization. We compared roe deer abundance and fawn body mass in two contrasted areas of a wolf pack territory: a central area (core of the territory characterized by an intense use by wolves) and a peripheral area (used more occasionally). Roe deer population growth rates were lower in the central area between 2001 and 2006, resulting in a decline in roe deer abundance. Roe deer abundance substantially dropped in the two study areas after an extremely severe winter but the abundance of roe deer in the central area facing with wolves was slower to recover and remained at lower abundance levels for 6 years. Fawn body mass was consistently lower in the central area, varied similarly as roe deer abundance, and was not influenced by weather conditions or red deer population abundance. Altogether, the effects of wolves on roe deer in the central area occurred during a 10-year period following the establishment of wolves, through the interplay between wolf predation (before wolves started preying on red deer), harsh winter conditions and possibly naivety of prey to this recolonizing predator. 相似文献
77.
Khaoula Rochdi Cerino Mathieu Da Silva Nathalie Delague Valerie Nahili Halima Kriouile Yamna Gorokhova Svetlana Bartoli Marc Saïle Rachid Barakat Abdelhamid Krahn Martin 《Molecular biology reports》2021,48(10):6999-7006
Molecular Biology Reports - Congenital myasthenic syndromes (CMS) are associated with defects in the structure and the function of neuromuscular junctions. These rare disorders can result from... 相似文献
78.
Cointet Eva Séverin Elise Couzinet-Mossion Aurélie Méléder Vona Gonçalves Olivier Wielgosz-Collin Gaëtane 《Journal of applied phycology》2021,33(4):2093-2103
Journal of Applied Phycology - In recent years diatoms have emerged as a major algal source for the production of bioactive compounds. Marine diatoms grow quickly and can store high amount of... 相似文献
79.
Ahmed Hamraoui Océane Sénépart Maxime Schneider Sophie Malaquin Emmanuel Péronne Loïc Becerra Fannie Semprez Claire Legay Laurent Belliard 《Biophysical journal》2021,120(3):402-408
Because of their role of information transmitter between the spinal cord and the muscle fibers, motor neurons are subject to physical stimulation and mechanical property modifications. We report on motoneuron elasticity investigated by time-resolved pump and probe spectroscopy. A dual picosecond geometry simultaneously probing the acoustic impedance mismatch at the cell-titanium transducer interface and acoustic wave propagation inside the motoneuron is presented. Such noncontact and nondestructive microscopy, correlated to standard atomic force microscopy or a fluorescent labels approach, has been carried out on a single cell to address some physical properties such as bulk modulus of elasticity, dynamical longitudinal viscosity, and adhesion. 相似文献
80.