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   949篇
  免费   40篇
  国内免费   4篇
化学   778篇
晶体学   9篇
力学   16篇
数学   35篇
物理学   155篇
  2023年   7篇
  2022年   11篇
  2020年   24篇
  2019年   18篇
  2018年   7篇
  2017年   6篇
  2016年   13篇
  2015年   24篇
  2014年   21篇
  2013年   48篇
  2012年   49篇
  2011年   67篇
  2010年   34篇
  2009年   31篇
  2008年   58篇
  2007年   45篇
  2006年   57篇
  2005年   46篇
  2004年   48篇
  2003年   35篇
  2002年   30篇
  2001年   17篇
  2000年   10篇
  1999年   17篇
  1998年   17篇
  1997年   11篇
  1996年   9篇
  1995年   6篇
  1994年   8篇
  1993年   6篇
  1992年   11篇
  1991年   6篇
  1990年   7篇
  1989年   6篇
  1988年   6篇
  1987年   8篇
  1986年   5篇
  1985年   21篇
  1984年   16篇
  1983年   15篇
  1982年   16篇
  1981年   10篇
  1980年   11篇
  1979年   16篇
  1978年   7篇
  1977年   12篇
  1976年   12篇
  1975年   6篇
  1974年   7篇
  1973年   6篇
排序方式: 共有993条查询结果,搜索用时 378 毫秒
101.
102.
Rotational transitions of fluoroacetylene in the ν1(CH stretch) vibrational state have been observed by the laser–microwave double resonance technique using a color center laser as a radiation source in the 3 μm region. The rotational constant and centrifugal distortion constant in the ν1state were determined to be 9684.310(16) MHz and 2.68(62) kHz, respectively, where the uncertainties given in parentheses correspond to 2.5 standard deviations.  相似文献   
103.
The extraction behavior of mono-, poly-, anal bis-(benzothiacrown ether)s is studied for alkali, alkaline-earth, heavy, and transition metal ions in the presence of picrate. These ethers show high selectivity for silver ion. Silver extractions from binary and quaternary mixtures of silver with heavy or transition metal ions were successful, except for mixtures with mercury(II) ion. Silver was extracted from a copper ore with ca. 80% recovery.  相似文献   
104.
105.
A synthesis of a novel and chemically stable homoisocarbacyclin analog, TY-11223 (3), has been accomplished. The analog (3), given intravenously or orally, showed potent and long-lasting activities in inhibiting platelet aggregation and, in addition, a good selectivity in biological activities.  相似文献   
106.
107.
Quark mixings and theor momentum dependences are discussed in a subquark model in which the weak current is made of the iso-doublet spinor subquarks. The Cabibbo angle is predicted to become larger as momentum transfer between quarks grows up.  相似文献   
108.
The infrared spectra of 1-phosphapropyne, CH3CP, and its perdeuteride, CD3CP, have been measured in the gaseous and solid states. The QK branches of perpendicular bands have been analyzed in terms of the usual quadratic expression in K. Fermi resonances were identified for the ν1, ν2 + ν3, 2ν3, 2ν60; and ν5, 2ν3 + ν8 band systems of CH3CP and the ν1, 2ν3, 2ν60; ν6, ν7 + ν8; and ν7, 3ν81 band systems of CD3CP. The xy Coriolis interaction was also identified between the ν3 and ν6 bands of the two species. All the fundamentals were assigned and the normal coordinate treatment was carried out along with the Coriolis constants, ζz.  相似文献   
109.
The chloro-bridged (carbene)organopalladium(II) complex, di-μ-chlorobis(1,3-diphenyl-2-imidazolidinylidenato-2-C,2′-C)dipalladium(II) underwent chlorine abstraction with silver perchlorate in the presence of a cyclic diolefin or an organic nitrile, to give new cationic (carbene)organopalladium(II) complexes coordinated with the respective substrates. These new complexes were characterized by means of elemental analysis, molar conductivities, and IR and 1H NMR spectroscopy.  相似文献   
110.
To report a new polymerization reaction phenomenon, this article examines the polymerization of butyl vinyl ether and N‐vinylcarbazole in the presence of 2‐benzoxypentafluoropropene [CF2?C(CF3)OCOC6H5 or BPFP]. The homopolymer of butyl vinyl ether was produced in the presence of a catalytic amount of BPFP in high yields. N‐Vinylcarbazole, which is a monomer well‐known for producing its homopolymer under cationic polymerization conditions, also yielded its homopolymer in the presence of BPFP. It was concluded that some cationic species would be yielded by the addition of BPFP. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 908–910, 2007.  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