全文获取类型
收费全文 | 933篇 |
免费 | 60篇 |
专业分类
993篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 20篇 |
2020年 | 9篇 |
2019年 | 11篇 |
2018年 | 7篇 |
2017年 | 6篇 |
2016年 | 16篇 |
2015年 | 47篇 |
2014年 | 46篇 |
2013年 | 78篇 |
2012年 | 104篇 |
2011年 | 76篇 |
2010年 | 53篇 |
2009年 | 45篇 |
2008年 | 66篇 |
2007年 | 66篇 |
2006年 | 54篇 |
2005年 | 48篇 |
2004年 | 64篇 |
2003年 | 43篇 |
2002年 | 50篇 |
2001年 | 7篇 |
2000年 | 11篇 |
1999年 | 5篇 |
1998年 | 9篇 |
1997年 | 8篇 |
1996年 | 11篇 |
1995年 | 5篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 1篇 |
排序方式: 共有993条查询结果,搜索用时 0 毫秒
991.
Laïla Rhazi Patrick Grillas Mouhssine Rhazi Jean-Christophe Aznar 《Hydrobiologia》2009,634(1):185-194
The aim of this work was to test the hypotheses that the species composition of the vegetation of one pool in Morocco change
continuously along with rainfall fluctuations, that among the vegetation can be recognized Pool species and Opportunistic
species with distinct dynamics in time. We expected the Pool species to show lower inter-annual variation than the Opportunistic
species. This hypothesis was tested in a 10-year study of the species composition of the vegetation along two permanent transects.
The results showed high cumulative species richness (95 species) with large differences between years and a predominance of
annual species (77). The proportion of Pool species during these 10 years was low (39%) when compared to opportunists (61%).
In dry years the Opportunistic species were dominant and declined during wet years. The number of Pool species was correlated
with the amount of rainfall. A large number of these species revealed a preference for wet years. No negative interaction
between annuals/perennials and pools/non-pools species was found, suggesting that competition was not a major process during
the survey. The intensity of the drought and flood stress, related to climate fluctuations, seems to be the main factors controlling
the species composition of the vegetation of this unstable habitat. However, beyond the inter-annual fluctuation of the species
composition of the vegetation a directional change was noticed. This directional change could result from a recovery process
of the vegetation during the first years of the study after a severe flood which extirpated most of the Opportunistic species
of the pool. In the last years this directional change of the species composition of the vegetation is less clear and random
recruitment of the Opportunistic species from the surrounding forested habitats could contribute to explain inter-annual changes.
The data collected over these 10 years led to the speculation of hypotheses on the consequences of climate change. The expected
reduction of humid years and of rainfall regionally may lead to important changes in the species composition of the vegetation
of the temporary pools in Morocco.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Guest editors: B. Oertli, R. Cereghino, A. Hull & R. Miracle
Pond Conservation: From Science to Practice. 3rd Conference of the European Pond Conservation Network, Valencia, Spain, 14–16
May 2008 相似文献
992.
993.
Axel Hartke Sandrine Bouché Jean-Christophe Giard Abdellah Benachour Philippe Boutibonnes Yanick Auffray 《Current microbiology》1996,33(3):194-199
The lactic acid tolerance response (LATR) of the lactic acid bacterium Lactococcus lactis subsp. lactis has been studied. A dramatic increase in survival to a severe acid stress (pH 3.9) was obtained by preexposing the cells
for 30 min to a mildly acid shock at pH 5.5. Whole-cell protein extract analysis revealed that during the acid tolerance response
33 polypeptides are induced over the level of naive cells. Among these are the major heat shock proteins DnaK and GroEL. In
conjunction with a previous report (Hartke et al. 1994), the results establish that L. lactis can adapt to lactic acid exposure in two different ways: a logarithmic phase LATR, which may be activated by protons, and
a stationary-phase LATR, which needs no activation by protons. Both systems are independent of de novo protein synthesis.
Received: 8 February 1996 / Accepted: 11 March 1996 相似文献