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   10124篇
  免费   335篇
  国内免费   32篇
化学   7071篇
晶体学   20篇
力学   151篇
综合类   1篇
数学   2058篇
物理学   1190篇
  2020年   74篇
  2019年   86篇
  2016年   183篇
  2015年   173篇
  2014年   231篇
  2013年   403篇
  2012年   266篇
  2011年   259篇
  2010年   228篇
  2009年   214篇
  2008年   291篇
  2007年   271篇
  2006年   295篇
  2005年   277篇
  2004年   251篇
  2003年   259篇
  2002年   268篇
  2001年   189篇
  2000年   171篇
  1999年   116篇
  1998年   111篇
  1997年   124篇
  1996年   112篇
  1995年   106篇
  1994年   115篇
  1993年   136篇
  1992年   133篇
  1991年   107篇
  1990年   123篇
  1989年   125篇
  1988年   131篇
  1987年   137篇
  1986年   113篇
  1985年   218篇
  1984年   191篇
  1983年   122篇
  1982年   168篇
  1981年   156篇
  1980年   194篇
  1979年   194篇
  1978年   196篇
  1977年   227篇
  1976年   185篇
  1975年   170篇
  1974年   135篇
  1973年   184篇
  1972年   92篇
  1971年   89篇
  1970年   69篇
  1933年   67篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
71.
72.
73.
A voting scheme assigns to each profile of alternatives reported byn individuals a compromise alternative. A voting scheme is strategy-proof if no individual is better off by lying, i.e., not reporting a best alternative. In this paper the main results concern the case where the set of alternatives is the Euclidean plane and the preferences are Euclidean. It is shown that for strategy-proof voting schemes continuity is equivalent to convexity of the range of the voting scheme. Using a result by Kim and Roush (1984), this leads to characterizations of surjective or unanimous, anonymous, strategy-proof voting schemes.Furthermore, the paper contains an extensive discussion of related results in the area.  相似文献   
74.
We present a new algorithm for the identification of ring pairs in Cherenkov detectors. The approach combines linear regression methods for the construction of an appropriate reference quantity, methods from statistics for the evaluation of hypotheses and Monte Carlo simulation runs for the tuning of threshold levels.  相似文献   
75.
Preservation mechanisms of trehalose in food and biosystems   总被引:15,自引:0,他引:15  
The stability or shelf-life of food and biomaterials has always been a critical issue in the food and pharmaceutical industry. Trehalose (alpha-D-glucopyranosyl-alpha-D-glucopyranoside), a non-reducing diglucose sugar found in nature, confers to certain plant and animal cells the ability to survive dehydration for decades and to restore activity soon after rehydration. The interaction between trehalose and cell membranes or proteins, however, remains a debated subject, and a significant amount of work has been done to elucidate the mechanisms resulting in this unique behavior of preservation. This study shows how an interfacial phenomena approach has led to the use of trehalose as an excipient during freeze drying of a variety of products in the pharmaceutical industry. It also suggests opportunities as an ingredient for dried and processed food, as well as a non-toxic cryoprotectant of vaccines and organs for surgical transplants.  相似文献   
76.
Five low-lying negative parity states of103Rh up to 1277 keV excitation energy were observed to be Coulomb excited with 2·5–4·5 MeV protons. The de-excitation gamma rays from these levels were identified in the singles spectra recorded with a 57 cc Ge(Li) detector. The level energies, branching ratios, reduced transition probabilitiesB(E2) and the multipole mixing ratios () were obtained. The 880, 1106 and 1277 keV levels have been Coulomb excited with protons for the first time. The ambiguity in theJ values for 803 and 1106 keV levels have been resolved using 2-fits, the assigned spin values are 1/2 and 5/2, respectively. The-values for 474·1 and 811·2 keV transitions were obtained for the first time. The results have been discussed in the light of previously reported results.The authors wish to thank Professor I. M. Govil for his active interest at various stages of this work. One of us (DCT) acknowledges the financial support from U.G.C., New Delhi, under Faculty Improvement Programme.  相似文献   
77.
78.
79.
80.
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