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   677篇
  免费   33篇
  国内免费   3篇
化学   547篇
晶体学   6篇
力学   24篇
数学   25篇
物理学   111篇
  2023年   5篇
  2022年   21篇
  2021年   19篇
  2020年   20篇
  2019年   20篇
  2018年   33篇
  2017年   11篇
  2016年   24篇
  2015年   23篇
  2014年   33篇
  2013年   43篇
  2012年   72篇
  2011年   54篇
  2010年   38篇
  2009年   29篇
  2008年   34篇
  2007年   36篇
  2006年   26篇
  2005年   27篇
  2004年   25篇
  2003年   19篇
  2002年   11篇
  2001年   14篇
  2000年   13篇
  1999年   3篇
  1998年   4篇
  1997年   3篇
  1996年   1篇
  1995年   8篇
  1994年   5篇
  1993年   4篇
  1992年   3篇
  1991年   3篇
  1990年   1篇
  1989年   2篇
  1988年   2篇
  1987年   1篇
  1986年   1篇
  1985年   6篇
  1984年   3篇
  1982年   4篇
  1981年   5篇
  1978年   2篇
  1977年   1篇
  1974年   1篇
排序方式: 共有713条查询结果,搜索用时 15 毫秒
91.
The ground state (ν = 0) rotational spectrum of 2-fluorobenzonitrile has been reinvestigated in the frequency range 40.0-99.0 GHz. The millimeter-wave spectrometer used is a source-modulated system combined with a free space glass cell. Millimeter-wave radiation has been produced using a Gunn diode and frequency doubler combination. High J and K−1 (J ? 49 and K−1 ? 18) transitions have been measured and accurate rotational and centrifugal distortion constants have been determined. Finally, the experimental values were compared with the corresponding values calculated at the HF/DFT-B3PW91/6-31g(d,p) level of theory. A very good agreement has been found.  相似文献   
92.
Increase in the specific surface area as well as Brownian motion are supposed to be the most significant reasons for the anomalous enhancement in thermal conductivity of nanofluids. This work presents a semi-empirical approach for the same by emphasizing the above two effects through micro-convection. A new way of modeling thermal conductivity of nanofluids has been explored which is found to agree excellently with a wide range of experimental data obtained by the present authors as well as the data published in literature  相似文献   
93.
In Part I of this paper we introduced extensive games with a non-atomic continuum of players. It was shown that the Nash plays (outcomes) are invariant of the information patterns on the game, provided that no player's unilateral change in moves can be observed by others. This led to an enormous reduction in the Nash plays of the these games, as exemplified in the anti-folk theorem. Our concern in this sequel is to develop a finite version of these results.  相似文献   
94.
95.
K S Joseph  B Pradeep 《Pramana》1994,42(1):41-47
Copper sulphide films prepared by reactive evaporation, when heated in air at 500 K, oxidized to Cu2O after a series of intermediate chemical transitions. Golden yellow coloured Cu2O films showed a large absorption before the fundamental absorption edge. The optical band gap was found to be (2.29±0.02)eV. When these Cu2O films were further heated they got converted to CuO and the optical band gap was found to be (2.17±0.02)eV.  相似文献   
96.
97.
98.
The contribution of the textures in the B-phase of superfluid 3He to the specific heat has been calculated. The specific heat is found to be divergent near Tc.  相似文献   
99.
An improvement in the previously reported seed-mediated chemical synthesis of gold nanorods (GNRs) is reported. Monodisperse GNRs have been synthesized in a one-step protocol. The addition of controlled quantity of sodium borohydride (NaBH4) directly into the growth solution produced uniform GNRs, formed by in situ nucleation and growth. In order to arrive at the conclusion, we studied the formation of GNRs with various seeds, of metals of widely differing crystal structures, and there were no variations in the properties of the GNRs formed. The role of NaBH4 in the growth of GNR, which has not been covered in previous reports, is discussed in detail. The dependence of longitudinal plasmon peak on the concentration of NaBH4 is compared with the dependence of residual concentration of NaBH4 in the seed solution, which is added to the growth solution in seed-mediated synthesis. The study shows that NaBH4 plays an important role in the formation of GNRs. This proposed protocol offers a number of advantages: one-step preparation of GNRs, significant reduction in the preparation time to 10 min, high monodispersity of GNRs, and tailorability of the aspect ratio depending on NaBH4 concentration. It is suggested that NaBH4 added to the growth solution leads to in situ formation of the seed particles of the size of 3–5 nm which enables the growth of GNRs. The growth of GNRs suggested here is likely to have an impact on the preparation of other anisotropic structures. Our single-pot methodology makes the procedure directly adaptable for commercial-scale production of GNRs and for their synthesis even in undergraduate laboratories.  相似文献   
100.
Using molecular dynamics simulations, we investigate the relation between the dynamic transitions of biomolecules (lysozyme and DNA) and the dynamic and thermodynamic properties of hydration water. We find that the dynamic transition of the macromolecules, sometimes called a "protein glass transition," occurs at the temperature of dynamic crossover in the diffusivity of hydration water and also coincides with the maxima of the isobaric specific heat C_{P} and the temperature derivative of the orientational order parameter. We relate these findings to the hypothesis of a liquid-liquid critical point in water. Our simulations are consistent with the possibility that the protein glass transition results from crossing the Widom line, which is defined as the locus of correlation length maxima emanating from the hypothesized second critical point of water.  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