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   1304篇
  免费   29篇
  国内免费   2篇
化学   1037篇
晶体学   12篇
力学   17篇
数学   35篇
物理学   234篇
  2021年   9篇
  2020年   12篇
  2019年   16篇
  2018年   6篇
  2016年   18篇
  2015年   19篇
  2014年   25篇
  2013年   52篇
  2012年   56篇
  2011年   81篇
  2010年   37篇
  2009年   38篇
  2008年   82篇
  2007年   60篇
  2006年   68篇
  2005年   67篇
  2004年   60篇
  2003年   46篇
  2002年   57篇
  2001年   36篇
  2000年   19篇
  1999年   13篇
  1998年   12篇
  1997年   9篇
  1996年   15篇
  1995年   6篇
  1994年   12篇
  1993年   20篇
  1992年   16篇
  1991年   23篇
  1990年   13篇
  1989年   12篇
  1988年   20篇
  1987年   30篇
  1986年   15篇
  1985年   27篇
  1984年   20篇
  1983年   12篇
  1982年   27篇
  1981年   25篇
  1980年   20篇
  1979年   16篇
  1978年   10篇
  1977年   17篇
  1976年   6篇
  1975年   9篇
  1974年   12篇
  1973年   8篇
  1968年   7篇
  1967年   6篇
排序方式: 共有1335条查询结果,搜索用时 15 毫秒
1.
We report the recent development on the SUSY calculations with the help of GRACE system. GRACE/SUSY/1LOOP is the computer code which can generate Feynman diagrams in the MSSM automatically and compute one-loop amplitudes in the numerical way. We present new results of various two-body decay widths and chargino pair production at ILC (international linear collider) at one-loop level.   相似文献   
2.
3.
A new cyclobutene-fused 1,6-methano[10]annulene was synthesized by pyrolysis of the sulfone and sulfinate adducts of 3,4-bis(methylene)-1,6-methano[10]annulene and its physical and chemical properties were disclosed.  相似文献   
4.
Reactions of pyrrolidine with 2 equiv of aldehydes without any catalyst in a pressurized vessel at 140–200 °C yielded 1,3-disubstituted pyrroles. -Branched aldehydes gave fairly good yields of the corresponding products by this method, which provides a facile non-oxidative procedure for synthesizing 1,3-dialkylpyrroles from inexpensive pyrrolidine and aldehydes.  相似文献   
5.
6.
7.
The first and second adsorption–desorption isotherms of water vapor on a new mesoporous material derived from kanemite have been measured. The isotherms show unusual type V isotherms and large hysteresis. The type V isotherms, which have never been observed for the other adsorbates, suggest that the mesoporous material has a hydrophobic surface, although the hydrophobicity decreased after treatment with water vapor because of rehydration of the surface. The significantly large hysteresis could be explained by the difference in contact angle between adsorption and desorption.  相似文献   
8.
We study the limit theorem related to the interface of the three-dimensional Ising model. Dobrushin proved that the interface does not fluctuate and becomes rigid for sufficiently large. We define the random fieldX L (t, s), 0t, s1, on the interface, and prove that XL(t, s) converges to the Brownian sheet as L for sufficiently large, whereL denotes the size of the system. This result does not mean that the interface itself converges to the Brownian sheet.  相似文献   
9.
Effect of titanium dioxide on photostability of solid-state mequitazine   总被引:1,自引:0,他引:1  
TiO(2) has been widely used in pharmaceutical products, and it also has been used as a photocatalyst. In this study, the influence of photocatalytic activity on the stability of solid-state mequitazine, an H(1)-blocker, was investigated. The photo-degradation of mequitazine with TiO(2) occurred under irradiation with both light sources. The degree of degradation of mequitazine with anatase was higher than that of rutile. The degradation was significantly enhanced with increasing relative humidity. The relationship between the apparent degradation rate constant and water vapor pressure could be clearly described by a simple power law. The major photo-degradation products of mequitazine, resulting from photocatalytic activity of TiO(2), were mequitazine-S-oxide and mequitazine-sulphone. A remarkable degradation of mequitadine occurred with addition of TiO(2), and its photocatalytic activity was controlled by water vapor pressure. The photo-degradation of mequitazine with TiO(2) is a different process from mequitazine without TiO(2), because mequitazine-S-oxide and mequitazine-sulphone are not formed with normal photo-degradation of mequitazine.  相似文献   
10.
Seventeen compounds having a variety of substituents at the 3- and 5′-positions of 2′-deoxy-5-fluorouridine (5-FUdR) and 5-fluorouridine (5-FUR) were synthesized, and their γ-radiolysis in aqueous solutions were studied. The compounds having thioureido (RNHCSNH, R ? H, PhCH2, acyl) and thiocarbonylamino (XCSNH, X ? PhCH2S, PhO) groups at the 3-position of 5-FUdR were efficiently cleaved to give 5-FUdR with high G values upon γ-irradiation of their aqueous solutions. The active species for these cleavage reactions were hydrated electron (e? aq), H? and HO?. However, the compounds having a dimethylsulfoxyimino group at 3-position of 5-FUdR and 5-FUR afforded 5-FUdR and 5-FUR only under the radiolysis conditions where e? aq becomes a principal active species. The compound having a 2-benzoylthiazoylthiocarbonylamino group at the 3-position of 5-FUdR showed the highest reactivity toward HO.. The mechanisms of these γ-radiolysis reactions are discussed. The examination of anticellular activities of γ-irradiated compounds having a thiocarbonylamino group at the 3-position of 5-FUdR toward murine Sarcoma 180 cells revealed that these compounds may be utilized as a candidate for a radiation-induced drug (RID).  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