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   1467362篇
  免费   139918篇
  国内免费   1422篇
  2021年   18061篇
  2019年   16286篇
  2018年   18245篇
  2017年   17019篇
  2016年   28701篇
  2015年   42902篇
  2014年   50995篇
  2013年   77663篇
  2012年   41237篇
  2011年   30376篇
  2010年   44918篇
  2009年   45944篇
  2008年   28525篇
  2007年   26893篇
  2006年   31528篇
  2005年   32396篇
  2004年   31553篇
  2003年   28939篇
  2002年   26916篇
  2001年   39431篇
  2000年   37372篇
  1999年   35593篇
  1998年   26151篇
  1997年   26129篇
  1996年   25666篇
  1995年   23820篇
  1994年   23635篇
  1993年   22803篇
  1992年   31045篇
  1991年   29653篇
  1990年   28308篇
  1989年   28735篇
  1988年   26594篇
  1987年   25320篇
  1986年   24158篇
  1985年   26055篇
  1984年   25214篇
  1983年   22303篇
  1982年   22065篇
  1981年   21348篇
  1980年   19855篇
  1979年   21845篇
  1978年   19938篇
  1977年   18966篇
  1976年   18070篇
  1975年   17930篇
  1974年   18349篇
  1973年   18630篇
  1972年   16176篇
  1971年   14565篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
671.
672.
673.
674.
675.
The binding affinities and selectivities of antagonists Figure 1 and Scheme 2 for the α1A-adrenoceptor are dependent on the stereochemical orientation of the groups at the C-4 and C-5 positions of the oxazolidinone ring. The unambiguous assignment of the relative and absolute configurations of the diastereomers of SNAP 7915 (Figure 1 and Scheme 2) is reported.  相似文献   
676.
The differences between the composition of volatile substances in two specimens of dry smoked sausages produced using a standard and experimental (a mixture of propionic acid bacteria and bifidobacteria) cultures were studied by capillary gas chromatography. It was found that the experimental starter culture intensified the flavor-formation processes as compared with the standard culture. The experimental specimen had richer qualitative and quantitative compositions and displayed more intensive aroma and flavor. The contents of lactones and volatile terpenoids in the experimental specimen were much higher than in the control. The organoleptic characteristics of experimental dry smoked sausage specimen were considerably better.  相似文献   
677.
678.
679.
Reduced strength after passive stretch of the human plantarflexors.   总被引:5,自引:0,他引:5  
The purpose of this study was to assess strength performance after an acute bout of maximally tolerable passive stretch (PS(max)) in human subjects. Ten young adults (6 men and 4 women) underwent 30 min of cyclical PS(max) (13 stretches of 135 s each over 33 min) and a similar control period (Con) of no stretch of the ankle plantarflexors. Measures of isometric strength (maximal voluntary contraction), with twitch interpolation and electromyography, and twitch characteristics were assessed before (Pre), immediately after (Post), and at 5, 15, 30, 45, and 60 min after PS(max) or Con. Compared with Pre, maximal voluntary contraction was decreased at Post (28%) and at 5 (21%), 15 (13%), 30 (12%), 45 (10%), and 60 (9%) min after PS(max) (P < 0.05). Motor unit activation and electromyogram were significantly depressed after PS(max) but had recovered by 15 min. An additional testing trial confirmed that the torque-joint angle relation may have been temporarily altered, but at Post only. These data indicate that prolonged stretching of a single muscle decreases voluntary strength for up to 1 h after the stretch as a result of impaired activation and contractile force in the early phase of deficit and by impaired contractile force throughout the entire period of deficit.  相似文献   
680.
Evidence that the intestinal microbiota is intrinsically linked with overall health, including cancer risk, is emerging. Moreover, its composition is not fixed but can be influenced by several dietary components. Dietary modifiers, including the consumption of live bacteria (probiotics) and indigestible or limited digestible food constituents such as oligosaccharides (prebiotics) and polyphenols or both (synbiotics), are recognized modifiers of the numbers and types of microbes and have been reported to reduce colon cancer risk experimentally. Microorganisms also have the ability to generate bioactive compounds from food components. Examples include equol from isoflavones, enterodiol and enterolactone from lignans and urolithins from ellagic acid, which have also been demonstrated to retard experimentally induced cancers. The gastrointestinal microbiota can also influence both sides of the energy balance equation, namely, as a factor influencing energy utilization from the diet and as a factor that influences host genes that regulate energy expenditure and storage. Because of the link between obesity and cancer incidence and mortality, this complex complexion deserves greater attention. Overall, a dynamic interrelationship exists between the intestinal microbiota and colon cancer risk, which can be modified by dietary components and eating behaviors.  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