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   49044篇
  免费   3544篇
  国内免费   169篇
  2023年   174篇
  2022年   588篇
  2021年   1012篇
  2020年   641篇
  2019年   780篇
  2018年   1145篇
  2017年   968篇
  2016年   1573篇
  2015年   2452篇
  2014年   2803篇
  2013年   3095篇
  2012年   4082篇
  2011年   3893篇
  2010年   2461篇
  2009年   2245篇
  2008年   3108篇
  2007年   2985篇
  2006年   2603篇
  2005年   2411篇
  2004年   2214篇
  2003年   1917篇
  2002年   1682篇
  2001年   1340篇
  2000年   1253篇
  1999年   1011篇
  1998年   415篇
  1997年   350篇
  1996年   261篇
  1995年   217篇
  1994年   218篇
  1993年   177篇
  1992年   329篇
  1991年   310篇
  1990年   268篇
  1989年   231篇
  1988年   175篇
  1987年   166篇
  1986年   132篇
  1985年   109篇
  1984年   79篇
  1983年   87篇
  1982年   65篇
  1981年   54篇
  1980年   55篇
  1979年   69篇
  1978年   52篇
  1977年   51篇
  1975年   44篇
  1974年   64篇
  1973年   43篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
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   
55.
56.
Summary Lactic acid produced by continuous culture of L.casei in an upflow packed bed reactor, was recovered with Amberlite IRA 400 in a fluidized bed column. Bed expansions of 1.25 and 2.25 were applied. Reutilization did not alter the capability of net recovery of 0.048 ± 0.01 g lactic acid/g resin. When 2200 cm/h of ascensional velocity was used, (bed expansion of 2.25), the resin adsorbed 39.3% of the initial lactic acid and 63.5% was eluted. This resin supported the highest exchange capacity of 0.126 g lactic acid/g resin. Applying high flow rates, the process has potential industrial applications due to the short time employed.  相似文献   
57.
The tissue polarity genes control the polarity of hairs, bristles and ommatidia in the adult epidermis of Drosophila. We report here the identification of a new tissue polarity gene named starry night (stan). Mutations in this essential gene alter the polarity of cuticular structures in all regions of the adult body. The detailed polarity phenotype of stan on the wing suggested that it is most likely a component of the frizzled (fz) pathway. Consistent with this hypothesis, stan appears to be downstream of and required for fz function. We molecularly cloned stan and found that it encodes a huge protocadherin containing nine cadherin motifs, four EGF-like motifs, two laminin G motifs, and seven transmembrane domains. This suggests that Stan functions in signal reception, perhaps together with Fz.  相似文献   
58.
59.
60.
Despite the efficacy of antiretroviral-based pre-exposure prophylactics (PrEP) in men who have sex with men, studies in women have produced widely varying outcomes. Recent evidence demonstrates that vaginal microbial communities are associated with increased HIV acquisition risk and may impact PrEP efficacy. Here, we investigate the mechanisms underlying how vaginal bacteria alter PrEP drug levels and impact HIV infection rates ex vivo. Using cervicovaginal lavages (CVLs) from women with or without bacterial vaginosis (BV), we identified microbial metabolism of PrEP drugs in BV samples through LC-MS/MS analysis of soluble drug levels and metabolite formation in dual T-cell cultures. CVL samples were assessed for microbiome analysis using sequencing of bacterial 16S rRNA genes. We also observed non-Lactobacillus bacteria that are associated with BV may potentially impact PrEP efficacy through increased HIV infection rates in co-cultures containing Lactobacillus or BV bacteria, PrEP drugs, CEM-GFP cells, and HIV-1LAI virus. Finally, we used these data to develop a novel predictive mathematical simulation modeling system to predict these drug interactions for future trials. These studies demonstrate how dysbiotic vaginal microbiota may impact PrEP drugs and provides evidence linking vaginal bacteria to PrEP efficacy in women.  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