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   2971篇
  免费   90篇
  国内免费   5篇
化学   2168篇
晶体学   28篇
力学   31篇
数学   138篇
物理学   701篇
  2021年   17篇
  2020年   24篇
  2019年   32篇
  2018年   34篇
  2017年   17篇
  2016年   56篇
  2015年   54篇
  2014年   58篇
  2013年   138篇
  2012年   127篇
  2011年   148篇
  2010年   96篇
  2009年   66篇
  2008年   158篇
  2007年   163篇
  2006年   159篇
  2005年   155篇
  2004年   153篇
  2003年   154篇
  2002年   142篇
  2001年   71篇
  2000年   81篇
  1999年   36篇
  1998年   30篇
  1997年   36篇
  1996年   50篇
  1995年   36篇
  1994年   43篇
  1993年   35篇
  1992年   37篇
  1991年   37篇
  1990年   29篇
  1989年   23篇
  1988年   33篇
  1987年   12篇
  1986年   20篇
  1985年   46篇
  1984年   48篇
  1983年   26篇
  1982年   32篇
  1981年   42篇
  1980年   42篇
  1979年   51篇
  1978年   44篇
  1977年   35篇
  1976年   28篇
  1975年   11篇
  1974年   13篇
  1973年   17篇
  1969年   10篇
排序方式: 共有3066条查询结果,搜索用时 46 毫秒
1.
Kobayashi  M.  Zhang  Y.  Ishikawa  H.  Sun  J.  Oddershede  J.  Juul Jensen  D.  Miura  H. 《Experimental Mechanics》2021,61(5):817-828
Experimental Mechanics - The internal strain distribution developing during plastic deformation is important for understanding the mechanical properties of polycrystalline materials. Such...  相似文献   
2.
Several 5-substituted derivatives of 7-ethoxycarbonyl-6,8-dimethyl-1(2H)- phthalazinone were prepared by means of nitration, reductive amination, and diazonium decomposition. The substituents introduced included NO2, NH2, F, Cl, CN. Among the derivatives, the fluorine compound was obtained only in poor yield because intramolecular cyclization occurred predominantly.  相似文献   
3.
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   
4.
A micellar electrokinetic chromatography (MEKC) method was developed for estimating the angiotensin-I converting enzyme (ACE) inhibitory activity by separating the hippuric acid liberated in the ACE reaction mixture in the presence of an inhibitor, captopril. The hippuric acid was successfully separated and detected by MEKC with a 25 mM sodium dodecyl sulfate solution in a 25 mM phosphate-50 mM borate buffer at pH 7.0; the total analysis took about 5 min. A good linear relationship was observed between the inhibitor and the peak area of hippuric acid release. No significant difference in the ACE inhibitory activity (IC50) of captopril (an antihypertensive medicine) or autolyzed-mushrooms (functional foods) was observed between the conventional method and the MEKC method. The MEKC method was found to be a useful technique for a rapid assay of the ACE inhibitory activity.  相似文献   
5.
A large-volume (100 microl) injection-ETAAS with W-treated PG furnace combined with a phosphate modifier was applied to the determination of unpolluted levels of Cd in tap, snow and river-water samples. The limit of detection of 1.1 ng l(-1) was observed for a 4 w/v% NH4H2PO4 modifer. Matrix interference studies were tested for major ion species well found in fresh water. The direct determination of Cd in certified river water (12 +/- 2 ng l(-1)) was carried out and the observed value was in agreement with the certified one. The good recoveries of Cd added to real environmental water samples were also observed. This method was applied to the determination of Cd in unpolluted environmental water samples.  相似文献   
6.
It was found that a beta-fructofuranosidase produced by Microbacterium sp. H-1 has potent trans-beta-fructofuranosylation activity from sucrose (donor). By means of this enzyme system, rebaudioside A (RA), the second major sweet steviol glycoside of the leaves of Stevia rebaudiana, was subjected to transfructosylation, affording a mono-beta-fructofuranosylated product (RA-F) in a high yield. The structure of RA-F was elucidated as beta-D-fructofuranosyl-(2----6)-beta-D-glucopyranosyl ester of steviol-13-O-[beta-D-glucopyranosyl-(1----2)]- [beta-D-glucopyranosyl-(1----3)]-beta-D-glucopyranoside. Some improvement in the quality of sweetness was observed for RA-F.  相似文献   
7.
8.
9.
The permeability of annealed poly (l-(trimethylsilyl)-l-propyne) was studied from the viewpoint of structural information obtained from x-ray diffraction and density. The sample cast from benzene solution had low density (0.82 g/cm3) and high permeability, whereas the annealed sample had a higher density (0.88 g/cm3) and permeability lower by two orders of magnitude. The smaller-angle x-ray diffraction peak for each sample, which was likely to reflect the distance between intermolecular chains, increased in intensity and shifted toward higher angle, corresponding to the change of the density with annealing. The logarithmic oxygen permeability was proportional to the density, namely the free volume fraction correlated with the diffusion coefficient and controlled by annealing and swelling by alcohols.  相似文献   
10.
A duality for orbifolds is presented as an application of group extensions in tensor categories.  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