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   28118篇
  免费   3714篇
  国内免费   3146篇
化学   20421篇
晶体学   360篇
力学   1390篇
综合类   238篇
数学   3538篇
物理学   9031篇
  2023年   440篇
  2022年   482篇
  2021年   697篇
  2020年   907篇
  2019年   926篇
  2018年   790篇
  2017年   757篇
  2016年   1123篇
  2015年   1145篇
  2014年   1361篇
  2013年   1910篇
  2012年   2286篇
  2011年   2525篇
  2010年   1771篇
  2009年   1750篇
  2008年   1937篇
  2007年   1774篇
  2006年   1589篇
  2005年   1400篇
  2004年   1113篇
  2003年   887篇
  2002年   814篇
  2001年   705篇
  2000年   569篇
  1999年   534篇
  1998年   478篇
  1997年   419篇
  1996年   452篇
  1995年   384篇
  1994年   367篇
  1993年   341篇
  1992年   320篇
  1991年   276篇
  1990年   232篇
  1989年   191篇
  1988年   167篇
  1987年   128篇
  1986年   141篇
  1985年   155篇
  1984年   101篇
  1983年   64篇
  1982年   71篇
  1981年   53篇
  1980年   52篇
  1979年   58篇
  1978年   40篇
  1976年   37篇
  1975年   32篇
  1974年   40篇
  1973年   45篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
72.
73.
Over the past few decades, the realm of inorganic medicinal chemistry has been dominated by the study of the anti-cancer properties of transition metal complexes, particularly those based on platinum or ruthenium. However, comparatively less attention has been focused on the development of metal complexes for the treatment of inflammatory or autoimmune diseases. Metal complexes possess a number of advantages that render them as attractive alternatives to organic small molecules for the development of therapeutic agents. In this perspective, we highlight recent examples in the development of transition metal complexes as modulators of inflammatory and autoimmune responses. The studies presented here serve to highlight the potential of transition metal complexes in modulating inflammatory or immune pathways in cells.  相似文献   
74.
75.
A new amino‐functionalized strontium–carboxylate‐based metal–organic framework (MOF) has been synthesized that undergoes single crystal to single crystal (SC‐to‐SC) transformation upon desolvation. Both structures have been characterized by single‐crystal X‐ray analysis. The desolvated structure shows an interesting 3D porous structure with pendent ?NH2 groups inside the pore wall, whereas the solvated compound possesses a nonporous structure with DMF molecules on the metal centers. The amino group was postmodified through Schiff base condensation by pyridine‐2‐carboxaldehyde and palladium was anchored on that site. The modified framework has been utilized for the Suzuki cross‐coupling reaction. The compound shows high activity towards the C?C cross‐coupling reaction with good yields and turnover frequencies. Gas adsorption studies showed that the desolvated compound had permanent porosity and was microporous in nature with a BET surface area of 2052 m2 g?1. The material also possesses good CO2 (8 wt %) and H2 (1.87 wt %) adsorption capabilities.  相似文献   
76.
77.
78.
In conventional research on beam gas coulomb scattering(BGCS), only the related beam lifetime using the analytical method is studied. In this paper, using the particle-in-cell Monte Carlo collisions(PIC-MCC) method,we not only simulated the beam lifetime but also explored the effect of BGCS on the beam distribution. In order to better estimate the effect on particle distribution, we study the ultra-low emittance electron beam. Here we choose the He Fei Advanced Light Source. By counting the lost particles in a certain time, the corresponding beam lifetime we simulated is 4.8482 h/13.8492 h in x/y, which is very close to the theoretic value(5.0555 h /13.7024 h in x/y).By counting the lost particles relative to the collided particles, the simulated value of the loss probability of collided particles is 1.3431e-04, which is also very close to the theoretical value(1.3824e-04). Besides, the simulation shows there is a tail in the transverse distribution due to the BGCS. The close match of the simulation with the theoretic value in beam lifetime and loss probability indicates our simulation is reliable.  相似文献   
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