全文获取类型
收费全文 | 364篇 |
免费 | 35篇 |
专业分类
399篇 |
出版年
2024年 | 1篇 |
2021年 | 4篇 |
2020年 | 1篇 |
2019年 | 7篇 |
2018年 | 7篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 16篇 |
2014年 | 12篇 |
2013年 | 30篇 |
2012年 | 23篇 |
2011年 | 17篇 |
2010年 | 21篇 |
2009年 | 13篇 |
2008年 | 19篇 |
2007年 | 30篇 |
2006年 | 27篇 |
2005年 | 17篇 |
2004年 | 23篇 |
2003年 | 21篇 |
2002年 | 16篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 5篇 |
1997年 | 8篇 |
1996年 | 4篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 7篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 6篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1971年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有399条查询结果,搜索用时 15 毫秒
391.
Bakker Freek T. Olsen Jeanine L Stam Wytze T. Van Den Hoek Chris 《Molecular phylogenetics and evolution》1994,3(4)
Evolutionary relationships among species traditionally ascribed to the Siphonocladales/Cladophorales have remained unclear due to a lack of phylogenetically informative characters and extensive morphological plasticity resulting in morphological convergence. This study explores some of the diversity within the generic complex Cladophora and its siphonocladalean allies. Twelve species of Cladophora representing 6 of the 11 morphological sections recognized by van den Hoek were analyzed along with 8 siphonocladalean species using 185 rRNA gene sequences. The final alignment consisted of 1460 positions containing 92 phylogenetically informative substitutions. Weighting schemes (EOR weighting, combinatorial weighting) were applied in maximum parsimony analysis to correct for substitution bias. Stem characters were weighted 0.66 relative to single-stranded characters to correct for secondary structural constraints. Both weighting approaches resulted in greater phylogenetic resolution. Results confirm that there is no basis for the independent recognition of the Cladophorales and Siphonocladales. The Siphonocladales is polyphyletic, and Cladophora is paraphyletic. All analyses support two principal lineages, of which one contains predominantly tropical members including almost all siphonocladalean taxa, while the other lineage consists of mostly warm- to cold-temperate species of Cladophora. 相似文献
392.
393.
P Mérat A Bordas Rolande L'Hospitalier Jeanine Protais M Bougon G Coquerelle M Le Menec M Launay 《遗传、选种与进化》1983,15(1):147-166
394.
Do trade‐offs between predation pressures on females versus nests drive nest‐site choice in painted turtles?
下载免费PDF全文
![点击此处可从《Biological journal of the Linnean Society. Linnean Society of London》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jeanine M. Refsnider Aaron M. Reedy Daniel A. Warner Fredric J. Janzen 《Biological journal of the Linnean Society. Linnean Society of London》2015,116(4):847-855
Predation strongly influences reproductive behaviours because reproducing individuals must balance mortality risks to themselves and to their offspring. In many freshwater turtles, the nest predation risk decreases with nest distance from water, whereas the predation risk to females increases farther from water. To determine whether predation pressure influences the distance from water at which female turtles nest, we measured predation pressure on nesting females and on nests, as well as the distances of nests to water, in two populations of painted turtles. Using models, we found that female survival in both populations was high and did not vary with distance from water. Nest survival was also uncorrelated with nest distance to water, although it was significantly lower than adult survival in both populations and was only 1.2% in one population. Our results suggest that nest sites are not predictably safe from predators. Instead, turtles may hedge their bets by nesting over a wide range of distances from water because any distance is risky for nests and no distance is particularly risky for the nesting female. We suggest that other factors, such as suitable incubation conditions and/or post‐emergence hatchling survival, probably play a larger role than predation in driving nest‐site choice in painted turtles. 相似文献
395.
396.
397.
Gérard Lefranc Marie-Paule Lefranc Jeanine Seger Jean-Philippe Salier Leila Chakhachiro Jacques Loiselet 《Human genetics》1981,58(3):294-297
Summary Hypohaptoglobinaemia and ahaptoglobinaemia occurred in three generations, mainly to male members of a family. Also small amounts of haptolobin were detected in most of the female relatives. Haemolytic anaemia seemed unlikely and the glucose 6 phosphate dehydrogenase (G.6.P.D.) activity was normal. The probable genotype of these apparently healthy individuals was Hp
2/Hp
2. These preliminary data might suggest a defect in control of gene expression by steroid hormones. 相似文献
398.
The extracellular matrix is essential for the integrity of the lung and when disrupted can lead to the architectural changes
seen in emphysema. The etiology of emphysema is believed to be due to an imbalance in the proteases and antiproteases within
the lung. Studies have focused on elastolytic enzymes as the primary agents in disease pathogenesis, however, recent data
suggest that collagenases may also be involved in the destruction of lung tissue in emphysema. It is hoped that this expanded
understanding of the pathophysiology of emphysema will lead to improved therapy in the treatment of the disease. 相似文献
399.
Jean-Luc Ridet Gérard Alonso Norbert Chauvet Jacqueline Chapron Jeanine Koenig Alain Privat 《Cell and tissue research》1995,283(1):39-49
A specific monoclonal antiserum (Mab 6.17) inducing a strong immunostaining of the neuromuscular junction has been used to
detect the possible occurrence of the corresponding antigen throughout the intact or lesioned central nervous system of adult
rats. In intact animals, 6.17-immunolabeling was essentially detected in astrocyte-like structures located in white matter
fasciculi of the brain, such as the optic tract, corpus callosum, fornix, and in the white matter of the spinal cord. The
astroglial nature of such 6.17-immunolabeled profiles was verified by performing double or triple immunofluorescent labeling
with Mab 6.17 and with specific antisera against astrocytic markers, such as S100 protein, glial fibrillary acidic protein
and vimentin. In the white matter, all the structures reactive to Mab 6.17 were also reactive to antibodies against S100 protein,
glial fibrillary acidic protein and vimentin. On the other hand, astrocytes of the grey matter that were immunoreactive to
S100 and glial fibrillary acidic protein but negative to vimentin, were devoid of 6.17-immunoreactivity. After lesions including
stab wound through the diencephalon or transection of the spinal cord, a marked increase of 6.17-immunostaining was noted
in the regions surrounding the lesions. In these regions, 6.17-immunolabeling was associated with S100-, GFAP- and vimentin-positive
astrocytes constituting the glial scar. The ultrastructural localization of 6.17-immunoreactivity indicated that, similar
to glial fibrillary acidic protein and vimentin, the recognized antigen was mainly associated with gliofilaments. These observations
indicate that, in the central nervous system of adult rats, Mab 6.17 recognizes a molecule associated with gliofilaments,
which is essentially associated to reactive astrocytes expressing high levels of vimentin.
Received: 2 May 1995 / Accepted: 31 July 1995 相似文献