首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   59004篇
  免费   5005篇
  国内免费   238篇
  2023年   188篇
  2021年   1100篇
  2020年   640篇
  2019年   839篇
  2018年   1267篇
  2017年   978篇
  2016年   1686篇
  2015年   2787篇
  2014年   3112篇
  2013年   3604篇
  2012年   4665篇
  2011年   4422篇
  2010年   2826篇
  2009年   2499篇
  2008年   3523篇
  2007年   3282篇
  2006年   3000篇
  2005年   2709篇
  2004年   2629篇
  2003年   2353篇
  2002年   1997篇
  2001年   1707篇
  2000年   1580篇
  1999年   1259篇
  1998年   548篇
  1997年   488篇
  1996年   420篇
  1995年   414篇
  1994年   321篇
  1993年   306篇
  1992年   654篇
  1991年   530篇
  1990年   488篇
  1989年   490篇
  1988年   417篇
  1987年   399篇
  1986年   328篇
  1985年   341篇
  1984年   275篇
  1983年   228篇
  1982年   196篇
  1981年   168篇
  1980年   166篇
  1979年   226篇
  1978年   198篇
  1977年   181篇
  1976年   175篇
  1974年   197篇
  1973年   155篇
  1972年   157篇
排序方式: 共有10000条查询结果,搜索用时 281 毫秒
101.
102.
N.C. Lee 《CMAJ》1990,142(11):1176-1177
  相似文献   
103.
104.
The purpose of this review is to provide an overview of the effects of adenovirus and influenza virus infections on obesity in various experimental models. We reviewed studies that were conducted within the past 10 years and were related to virus infection and obesity prevalence. Here, we discuss a different causal relationship between adenovirus and influenza infections with obesity. Adenovirus infection can cause obesity, whereas obesity can be a risk factor for increasing influenza virus infection and increases the risk of morbidity and mortality. The prevalence of obesity due to adenovirus infections may be due to an increase in glucose uptake and reduction in lipolysis caused by an increase in corticosterone secretion. Adenovirus infections may lead to increases in appetite by decreasing norepinephrine and leptin levels and also cause immune dysfunction. The relationship between obesity and influenza virus infection could be summarized by the following features: decreases in memory T-cell functionality and interferon (IFN)-α, IFN-β, and IFN-γ mRNA expression, increases in viral titer and infiltration, and impaired dendritic cell function in obese individuals. Moreover, leptin resistance may play an important role in increasing influenza virus infections in obese individuals. In conclusion, prevention of adenovirus infections could be a good approach for reducing obesity prevalence, and prevention of obesity could reduce influenza virus infections from the point of view of viral infections and obesity.  相似文献   
105.
The genome sequence analysis of a clinical Vibrio cholerae VC35 strain from an outbreak case in Malaysia indicates multiple genes involved in host adaptation and a novel Na+-driven multidrug efflux pump-coding gene in the genome of Vibrio cholerae with the highest similarity to VMA_001754 of Vibrio mimicus VMA223.  相似文献   
106.
Focal animal sampling was used to determine the 24-h time budget of a takh harem stallion (Equus ferus przewalskii) during the 2 weeks prior to, and the two weeks following, reintroduction into the Hustain Nuruu Steppe Reserve, Mongolia. Both before and after release, the stallion spent approximately 47% of his time grazing, 6% standing, and 5% in recumbent rest. The biggest changes to the time budget after release were a 4-fold increase in the amount of time spent moving, and a 50% decrease in the amount of time spent resting in a standing position. During the middle of the day when the temperatures were hottest, the stallion exhibited less grazing and more standing resting behaviour than in the morning or evening hours. Recumbent rest invariably occurred in the hours before dawn.  相似文献   
107.
108.
109.
110.
Fluorescamine and trinitrobenzenesulfonate were used as chemical probes to differentially label amino phospholipids in liposomes. At low concentrations, fluorescamine reacts primarily with amino lipids on the external half of the bilayer. Further increase in fluorescamine concentration resulted in a linear increase of labeling indicating penetration and reaction with the internal half of the bilayer. Because of the pH requirements of the fluorescamine reaction, internal labeling was eliminated with a H+ gradient: inside acidic/outside alkaline. Differential labeling was also achieved with trinitrobenzenesulfonate, which is normally not permeable but which can be transported by valinomycin-K+ complex and react with internal amines. Thus, either half of the bilayer can be labeled with the same or different reagents. When liposomes were double-labeled, the fluorescence of fluorescamine was quenched by the trinitrobenzenesulfonate label. This quenching was reversed by solubilizing the liposomes with acidic ethanol. No quenching occurred when fluorescamine-labeled liposomes were mixed with trinitrobenzenesulfonate-reacted liposomes (or trinitrophenylated methylamine) suggesting close proximity of two labels is required for quenching. Conditions which promoted vesicular fusion promptly produced quenching. These differential labeling procedures can be usefully applied to quantitate aminolipids on internal and external vesicular surface, monitor vesicular fusion, and assess liposomal structure.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号