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   2506篇
  免费   88篇
  国内免费   14篇
化学   1962篇
晶体学   25篇
力学   28篇
数学   149篇
物理学   444篇
  2023年   11篇
  2022年   17篇
  2021年   27篇
  2020年   29篇
  2019年   43篇
  2018年   28篇
  2017年   21篇
  2016年   60篇
  2015年   41篇
  2014年   57篇
  2013年   158篇
  2012年   132篇
  2011年   173篇
  2010年   106篇
  2009年   98篇
  2008年   151篇
  2007年   142篇
  2006年   135篇
  2005年   130篇
  2004年   119篇
  2003年   108篇
  2002年   84篇
  2001年   49篇
  2000年   38篇
  1999年   35篇
  1998年   28篇
  1997年   33篇
  1996年   23篇
  1995年   22篇
  1994年   36篇
  1993年   25篇
  1992年   29篇
  1991年   32篇
  1990年   22篇
  1989年   18篇
  1988年   18篇
  1987年   15篇
  1986年   17篇
  1985年   33篇
  1984年   32篇
  1983年   14篇
  1982年   25篇
  1981年   25篇
  1980年   21篇
  1979年   20篇
  1976年   18篇
  1975年   13篇
  1974年   10篇
  1973年   16篇
  1969年   10篇
排序方式: 共有2608条查询结果,搜索用时 15 毫秒
51.
Abstract Mono-DPTA-ethyleneglycol-Ga-deuteroporphyrin (MDEGD) was synthesized, by coordinating non-radioactive Ga in the porphyrin ring and connecting DTPA (diethylene-triamine-N,N,N,N,N,-pentaacetic acid) to its side chain. By labeling with 111In, chemicals for scintigraphy were developed. They were applied to Syrian golden hamsters with implanted pancreatic gland cancers and C57-black mice with Lewis lung cancer to enable tumor imaging and biodistribution examination. A comparative study was also conducted with [67Ga]citrate. In the resultant data, [111In]MDEGD showed larger tumor/lung, tumor/kidney and tumor/blood ratio with [67Ga]citrate. The affinity of [nIn]MDEGD in inflammatory tissue was much lower than that of 67Ga citrate. [111In]MDEGD lost its photosensitivity.  相似文献   
52.
A convergent total synthesis of cis-solamin (1a) and its diastereomer (1b) was accomplished. A key reaction of this approach was the use of VO(acac)2-catalyzed diastereoselective epoxidation of (Z)-bis-homoallylic alcohol 3 followed by spontaneous cyclization for the cis-THF ring formation. By comparison of the optical rotation of the two possible diastereomers, it is suggested that the absolute configuration of natural cis-solamin is 1a. Inhibitory action of synthetic 1a and 1b with bovine heart mitochondrial complex I are reported.  相似文献   
53.
54.
Intermittent behaviour of fragment multiplicity distributions in the nuclear liquid-gas phase transition is studied in terms of the droplet model of Fisher. The anomalous fractal dimensions are compared with data on heavy ion reactions and classical molecular dynamics simulations. A signature of the transition in the anomalous fractal dimensions is shown.We thank Profs. S. Ayik, M. Di Toro and V. Kondratyev for discussions. One of us (T.K.) acknowledges the support of INFN-LNS.  相似文献   
55.
56.
We have carried out SR experiments on [Co(NH3)6]Cl3 and [Co(ND3)6]Cl3. At 293 K, all the muons implanted into the complexes were in the diamagnetic state. The observed Gaussian-type muon spin relaxation function proved that the internal magnetic field was caused by nuclear dipole moments of the atoms in the complexes. In addition, another exponential-type muon spin relaxation function was observed in [Co(ND3)6]Cl3 below 50 K.  相似文献   
57.
58.
We shall introduce a generalized Aluthge transformation on -
hyponormal operators and also, by using the Furuta inequality, we shall give several properties on this generalized Aluthge transformation as further extensions of some results of Aluthge.

  相似文献   

59.
60.
ZnO nanoparticles with spherical morphology and narrow size distribution were obtained by calcination of Zn(OH)2 nanoparticles, which were prepared in a polyethylene glycol mono-4-nonylphenyl ether (NP-5)/cyclohexane reverse micellar system and incorporated into polyurea (PUA) via an in situ polymerization of hexamethylene diisocyanate (HDI). The resulting ZnO nanoparticles demonstrated a near-UV emission and a green emission, the intensity ratio of which depended on calcination conditions. For the nanoparticles studied, the calcination atmosphere influenced remarkably the photoluminescence properties such as intensity ratio of the near-UV emission to green emission, rather than the size, morphology, and crystallinity of the ZnO nanoparticles. The green emission decreased by calcination in O2 flow but increased by calcination in N2 flow, as compared with the case calcined in air flow. This finding suggests that the green emission is enhanced with the increase of the number of oxygen vacancies of the ZnO nanoparticles and thus the photoluminescence properties of the nanoparticles were successfully controlled by the calcination condition, without changing the size and morphology.  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