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   1934篇
  免费   93篇
  国内免费   7篇
化学   1437篇
晶体学   18篇
力学   29篇
数学   137篇
物理学   413篇
  2023年   15篇
  2022年   19篇
  2021年   12篇
  2020年   31篇
  2019年   33篇
  2018年   25篇
  2017年   22篇
  2016年   62篇
  2015年   36篇
  2014年   55篇
  2013年   96篇
  2012年   117篇
  2011年   150篇
  2010年   74篇
  2009年   63篇
  2008年   143篇
  2007年   118篇
  2006年   123篇
  2005年   110篇
  2004年   122篇
  2003年   81篇
  2002年   73篇
  2001年   42篇
  2000年   38篇
  1999年   33篇
  1998年   19篇
  1997年   23篇
  1996年   23篇
  1995年   15篇
  1994年   19篇
  1993年   11篇
  1992年   12篇
  1991年   13篇
  1990年   11篇
  1989年   12篇
  1988年   10篇
  1987年   14篇
  1986年   12篇
  1985年   18篇
  1984年   15篇
  1983年   15篇
  1982年   13篇
  1981年   11篇
  1980年   9篇
  1979年   15篇
  1978年   8篇
  1977年   9篇
  1976年   7篇
  1975年   5篇
  1971年   4篇
排序方式: 共有2034条查询结果,搜索用时 15 毫秒
1.
Journal of Radioanalytical and Nuclear Chemistry - Extraction chromatography flow-sheet employing octyl(phenyl)-N,N-diisobutylcarbonoylmethylphosphine oxide and bis(2-ethylhexyl) hydrogen phosphate...  相似文献   
2.
Tsuyoshi Kitamura 《Tetrahedron》2004,60(43):9649-9657
Synthesis of (+)-anthramycin was examined. A pyrrolobenzodiazepine skeleton could be synthesized by reductive cyclization of pyrrolidine derivative, which was obtained by enyne metathesis. The conjugated enamide ester part of (+)-anthramycin derivative was constructed by cross-metathesis.  相似文献   
3.
4.
This paper derives a conservation law for mean waiting times in a single-server multi-class service queueing system (M X/G/1 type queue) with setup times which may be dependent on multiple customer classes and its arrival batch size by using the work decomposition property in the queueing system with vacations.  相似文献   
5.
We investigate low-temperature behaviors of a system with chirality-pair interaction on a one-dimensional lattice. In the course of the investigation, we evaluate asymptotic forms of the characteristic values of the integral equation satisfied by the Mathieu functions. It turns out that the low-temperature behavior of correlation length of the chirality-pair correlation function is different from the one for the Ising model of spin ±1 but akin to the one for the Ising model of infinite spin.  相似文献   
6.
Two-mass models of the vocal cords for natural sounding voice synthesis   总被引:1,自引:0,他引:1  
Three new two-mass models of the vocal cords are treated. First, the features, structure, and differential equations of motion are described for each of the new models and compared with those of previous models. Second, performances of the models are discussed in terms of glottal volume flow, glottal area, radiated sound pressure, trajectories of mass movement, running spectra of the output sound pressure, and perceptual naturalness of the output sound. Finally, the major effects of glottal source-vocal tract interaction including skewing, truncation, and superposition are investigated, using one of the simplest types of two-mass models and two types of load representing the vocal tract.  相似文献   
7.
A compact high-resolution optical heterodyne interferometer combining a two-frequency light module and a minute optical system is described. The light module, which generates two independent frequencies of light, is fabricated by proton exchange method on LiNbO3 substrate. We report an experiment evaluating measurement accuracy using a micro-displacement measurement system which incorporates this interferometer. Results of the experiment with a standard thickness sample show high thermal stability with maximum measurement error of 1.8 nm at a temperature from 19°C to 33°C. The system was used to measure the hysteresis of a piezoelectric element for displacements of several nm, thereby making it possible to analyze the system quantitatively in practice.  相似文献   
8.
Organic dyes such as water soluble porphyrins were incorporated into monodispersed SiO2 particles using the sol-gel technique (the Stober synthesis) and their monomeric and dimeric properties were investigated by aiming at the microcavity effect. Doping efficiencies of dyes into SiO2 particles depended on dye's hydrophilic properties. The doping efficiency of a porphyrin, TTMAPP, decreased with increasing the nominal content in the starting solution and the doping content showed the maximum value of 1.6×10–5 mol/g SiO2. With increasing the TTMAPP content, spectra of doped particles were changed from dimeric to monomeric nature; the absorption peak due to dimers disappeared and halfwidth of absorption at Soret band decreased. This unusual change was caused by the decrease of particle sizes by dye doping. The TTMAPP-doped sample having monomeric spectrum showed the fluorescence life time of 8.5 nsec and photochemical hole burning at about 5 K.  相似文献   
9.
10.
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