全文获取类型
收费全文 | 1157篇 |
免费 | 161篇 |
专业分类
1318篇 |
出版年
2018年 | 14篇 |
2016年 | 20篇 |
2015年 | 31篇 |
2014年 | 37篇 |
2013年 | 41篇 |
2012年 | 55篇 |
2011年 | 50篇 |
2010年 | 30篇 |
2009年 | 37篇 |
2008年 | 42篇 |
2007年 | 36篇 |
2006年 | 34篇 |
2005年 | 34篇 |
2004年 | 38篇 |
2003年 | 34篇 |
2002年 | 31篇 |
2001年 | 30篇 |
2000年 | 35篇 |
1999年 | 33篇 |
1998年 | 21篇 |
1997年 | 13篇 |
1996年 | 8篇 |
1995年 | 20篇 |
1994年 | 20篇 |
1993年 | 11篇 |
1992年 | 25篇 |
1991年 | 25篇 |
1990年 | 26篇 |
1989年 | 19篇 |
1988年 | 24篇 |
1987年 | 21篇 |
1986年 | 17篇 |
1985年 | 24篇 |
1984年 | 17篇 |
1983年 | 9篇 |
1982年 | 11篇 |
1981年 | 14篇 |
1980年 | 12篇 |
1979年 | 20篇 |
1978年 | 15篇 |
1977年 | 9篇 |
1976年 | 11篇 |
1975年 | 18篇 |
1974年 | 19篇 |
1973年 | 20篇 |
1972年 | 16篇 |
1971年 | 9篇 |
1970年 | 10篇 |
1969年 | 13篇 |
1968年 | 9篇 |
排序方式: 共有1318条查询结果,搜索用时 0 毫秒
151.
152.
N. A. Moltschaniwskyj K. Hall Marek R. Lipinski J. E. A. R. Marian M. Nishiguchi M. Sakai D. J. Shulman B. Sinclair D. L. Sinn M. Staudinger R. Van Gelderen R. Villanueva K. Warnke 《Reviews in Fish Biology and Fisheries》2007,17(2-3):455-476
When using cephalopods as experimental animals, a number of factors, including morality, quality of information derived from
experiments, and public perception, drives the motivation to consider welfare issues. Refinement of methods and techniques
is a major step in ensuring protection of cephalopod welfare in both laboratory and field studies. To this end, existing literature
that provides details of methods used in the collection, handling, maintenance, and culture of a range of cephalopods is a
useful starting point when refining and justifying decisions about animal welfare. This review collates recent literature
in which authors have used cephalopods as experimental animals, revealing the extent of use and diversity of cephalopod species
and techniques. It also highlights several major issues when considering cephalopod welfare; how little is known about disease
in cephalopods and its relationship to senescence and also how to define objective endpoints when animals are stressed or
dying as a result of the experiment. 相似文献
153.
Charles R. Harrington John M. D. Storey Scott Clunas Kathleen A. Harrington David Horsley Ahtsham Ishaq Steven J. Kemp Christopher P. Larch Colin Marshall Sarah L. Nicoll Janet E. Rickard Michael Simpson James P. Sinclair Lynda J. Storey Claude M. Wischik 《The Journal of biological chemistry》2015,290(17):10862-10875
Alzheimer disease (AD) is a degenerative tauopathy characterized by aggregation of Tau protein through the repeat domain to form intraneuronal paired helical filaments (PHFs). We report two cell models in which we control the inherent toxicity of the core Tau fragment. These models demonstrate the properties of prion-like recruitment of full-length Tau into an aggregation pathway in which template-directed, endogenous truncation propagates aggregation through the core Tau binding domain. We use these in combination with dissolution of native PHFs to quantify the activity of Tau aggregation inhibitors (TAIs). We report the synthesis of novel stable crystalline leucomethylthioninium salts (LMTX®), which overcome the pharmacokinetic limitations of methylthioninium chloride. LMTX®, as either a dihydromesylate or a dihydrobromide salt, retains TAI activity in vitro and disrupts PHFs isolated from AD brain tissues at 0.16 μm. The Ki value for intracellular TAI activity, which we have been able to determine for the first time, is 0.12 μm. These values are close to the steady state trough brain concentration of methylthioninium ion (0.18 μm) that is required to arrest progression of AD on clinical and imaging end points and the minimum brain concentration (0.13 μm) required to reverse behavioral deficits and pathology in Tau transgenic mice. 相似文献
154.
155.
Human conflict generally has substantial negative impacts on wildlife and conservation. The recent civil war (1995-2006) in the Democratic Republic of Congo (DRC) resulted in a significant loss of wildlife, including elephants, due to institutional collapse, lawlessness and unbridled exploitation of natural resources such as minerals, wood, ivory and bushmeat. We used data from distance sampling surveys conducted before and after the war in a protected forest, the Okapi Faunal Reserve, to document changes in elephant abundance and distribution. We employed Generalized Additive Models to relate changes in elephant distribution to human and environmental factors. Populations declined by nearly fifty percent coinciding with a major increase in elephant poaching as indicated by reports of ivory trade during the war. Our results suggest that humans influenced elephant distribution far more than habitat, both before and after the war, but post-war models explained more of the variation. Elephant abundance declined more, closer to the park boundary and to areas of intense human activity. After the war, elephant densities were relatively higher in the centre of the park where they were better protected, suggesting that this area may have acted as a refuge. In other sites in Eastern DRC, where no protection was provided, elephants were even more decimated. Post-war dynamics, such as weakened institutions, human movements and availability of weapons, continue to affect elephants. Survival of remaining populations and recovery will be determined by these persistent factors and by new threats associated with growing human populations and exploitation of natural resources. Prioritizing wildlife protection, curbing illegal trade in ivory and bushmeat, and strengthening national institutions and organizations in charge of conservation will be crucial to counter these threats. 相似文献
156.
D. C. Sinclair 《BMJ (Clinical research ed.)》1949,1(4602):476-478
157.
R. G. Sinclair 《CMAJ》1938,38(5):491-492
158.
159.
160.
Chapman KE Sinclair SE Zhuang D Hassid A Desai LP Waters CM 《American journal of physiology. Lung cellular and molecular physiology》2005,289(5):L834-L841
Overdistention of lung tissue during mechanical ventilation may be one of the factors that initiates ventilator-induced lung injury (VILI). We hypothesized that cyclic mechanical stretch (CMS) of the lung epithelium is involved in the early events of VILI through the production of reactive oxygen species (ROS). Cultures of an immortalized human airway epithelial cell line (16HBE), a human alveolar type II cell line (A549), and primary cultures of rat alveolar type II cells were cyclically stretched, and the production of superoxide (O2-) was measured by dihydroethidium fluorescence. CMS stimulated increased production of O2- after 2 h in each type of cell. 16HBE cells exhibited no significant stimulation of ROS before 2 h of CMS (20% strain, 30 cycles/min), and ROS production returned to control levels after 24 h. Oxidation of glutathione (GSH), a cellular antioxidant, increased with CMS as measured by a decrease in the ratio of the reduced GSH level to the oxidized GSH level. Strain levels of 10% did not increase O2- production in 16HBE cells, whereas 15, 20, and 30% significantly increased generation of O2-. Rotenone, a mitochondrial complex I inhibitor, partially abrogated the stretch-induced generation of O2- after 2 h CMS in 16HBE cells. NADPH oxidase activity was increased after 2 h of CMS, contributing to the production of O2-. Increased ROS production in lung epithelial cells in response to elevated stretch may contribute to the onset of VILI. 相似文献