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   9829篇
  免费   344篇
  国内免费   43篇
化学   7018篇
晶体学   142篇
力学   200篇
综合类   1篇
数学   1230篇
物理学   1625篇
  2023年   58篇
  2021年   111篇
  2020年   184篇
  2019年   180篇
  2018年   114篇
  2017年   105篇
  2016年   234篇
  2015年   243篇
  2014年   256篇
  2013年   441篇
  2012年   480篇
  2011年   577篇
  2010年   358篇
  2009年   349篇
  2008年   525篇
  2007年   547篇
  2006年   514篇
  2005年   493篇
  2004年   430篇
  2003年   361篇
  2002年   373篇
  2001年   167篇
  2000年   154篇
  1999年   110篇
  1998年   120篇
  1997年   113篇
  1996年   151篇
  1995年   124篇
  1994年   93篇
  1993年   99篇
  1992年   91篇
  1991年   103篇
  1990年   91篇
  1989年   81篇
  1988年   74篇
  1987年   72篇
  1986年   67篇
  1985年   134篇
  1984年   90篇
  1983年   74篇
  1982年   95篇
  1981年   117篇
  1980年   129篇
  1979年   82篇
  1978年   91篇
  1977年   109篇
  1976年   87篇
  1975年   65篇
  1974年   57篇
  1973年   73篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
An interval-parameter fuzzy linear programming method (IFMOLP) is proposed in this study for multiple objective decision-making under uncertainty. As a hybrid of interval-parameter and fuzzy methodologies, the IFMOLP incorporates interval-parameter linear programming and fuzzy multiobjective programming approaches to form an integrated optimization system. The method inherits advantages of interval-parameter programming, and allows uncertainties and decision-makers’ aspirations to be effectively communicated into its programming processes and resulting solutions. Membership functions for both objectives and constraints are formulated to reflect uncertainties in different system components and their interrelationships. An interactive solution procedure has been developed based on solution approaches of the interval-parameter and fuzzy programming techniques, plus necessary measures for handling the multiobjective feature. A didactic example is provided in the paper to illustrate the detailed solution process. Possibilities of further improvements by seeking Pareto optimum and incorporating flexible preference within constraints are also discussed.  相似文献   
54.
We respond to criticisms of our paper “The Free Will Theorem”, and produce a new form of the theorem based on weaker assumptions.  相似文献   
55.
56.
Abstract— The effect of UVB exposure on the distribution and synthesis of dermal proteoglycans was measured in the skin of hairless mice. Two groups of mice were included: one was irradiated for 10 weeks; the other was kept as control. After intraperitoneal injection of sodium 35S-sulfate, punch biopsies were taken for histology and proteoglycans were extracted from the remaining skin with 4 M guanidinium chloride, containing 3–[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (0.5%, weight per volume). Following proteolytic digestion, the glycosaminoglycan constituents were isolated and analyzed by quantitative cellulose acetate electrophoresis and enzymatic digestibility.
Under the influence of UVB radiation, newly synthesized proteoglycans measured by 35SO4 uptake increased as much as 60%. In addition, the irradiated skin had a higher average content of proteoglycan than had control skin (4981 μg vs 4134 μg/g dry weight). This could be ascribed to an increase in heparin (1400 vs 533 μ g/g dry weight) and heparan sulfate (472 vs 367 μg/g dry weight), whereas no change in the concentration of hyaluronic acid (1243 vs 1372 μg/g dry weight) and dermatan sulfate (1866 vs 1863 μg/g dry weight) was observed. The irradiated animals also exhibited a marked increase in the synthesis of heparan sulfate and heparin (62% and 71%, respectively). These results demonstrate that chronic doses of UVB altered proteoglycan metabolism through both quantitative and qualitative changes.  相似文献   
57.
We obtain partial results on the conjecture that for the almost Mathieu operator at irrational frequency, , the measure of the spectrum,S(, , )=|4–2|. For ||2 we show that if n is rational and irrational, then .Dedicated to Res Jost and Arthur WightmanResearch partially supported by U.S. NSF grant number DMS-8801918 and by BSF under grant number 88-00325  相似文献   
58.
59.
60.
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