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   9684篇
  免费   200篇
  国内免费   21篇
化学   6199篇
晶体学   95篇
力学   191篇
数学   1222篇
物理学   2198篇
  2020年   83篇
  2018年   81篇
  2016年   164篇
  2015年   146篇
  2014年   146篇
  2013年   342篇
  2012年   333篇
  2011年   345篇
  2010年   219篇
  2009年   234篇
  2008年   321篇
  2007年   338篇
  2006年   315篇
  2005年   322篇
  2004年   274篇
  2003年   253篇
  2002年   253篇
  2001年   200篇
  2000年   217篇
  1999年   164篇
  1998年   142篇
  1997年   158篇
  1996年   163篇
  1995年   152篇
  1994年   124篇
  1993年   166篇
  1992年   140篇
  1991年   124篇
  1990年   89篇
  1989年   115篇
  1988年   124篇
  1987年   110篇
  1986年   121篇
  1985年   179篇
  1984年   141篇
  1983年   111篇
  1982年   133篇
  1981年   148篇
  1980年   96篇
  1979年   135篇
  1978年   116篇
  1977年   124篇
  1976年   110篇
  1975年   110篇
  1974年   89篇
  1973年   96篇
  1971年   74篇
  1968年   98篇
  1967年   108篇
  1966年   111篇
排序方式: 共有9905条查询结果,搜索用时 31 毫秒
971.
Treatment of CuCl with the lithiated silyl amides RSi(NLiPh)3 (R = Me, Ph, Vin) in THF as solvent led to the formation of the novel CuI cluster compounds [Li(THF)4]2[Cu10{RSi(NPh)3}4]. For each of the three compounds the X‐ray crystal structure analysis revealed similar Si4N12Cu10 cores which are based on cubane like Cu8 cores bearing two additional peripheral copper atoms. The copper atoms are coordinated nearly linearly by the μ5‐bridging silyl amide ligands with Cu–N distances in the range of 187.1(3) to 194.5(4) pm and N–Cu–N angles of 171.6(1) to 178.7(1)°. For each of the compounds the structural parameters are very similar which indicates that the structures are barely influenced by the different steric requirements of the organic groups bound to silicon.  相似文献   
972.
973.
974.
Fully mass printed, flexible and truly polymeric organic field effect transistors consisting of a three layer dielectric made of CYTOP (low‐k), PVA (intermediate) and P(VDF‐TrFE‐CTFE)(high‐k) are introduced. Gravure‐, flexo‐and screen printing were selected as highly productive manufacturing technologies. These OFETs work at strongly reduced voltages and show high field effect mobility (µ = 0.2 cm2/Vs) and remarkable good bias stress stability at very high current density (50 µA/mm). Fully printed OFETs are used for the realization of ring oscillators working in the kHz regime at reduced supply voltage (10 V). In combination with printed fully polymeric piezoelectric loudspeakers, this work shows for the first time fully printed flexible audio systems. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1409–1415  相似文献   
975.
A light induced strategy for the design of β‐cyclodextrin (CD) based supramolecular devices is introduced, presenting a novel tool to fabricate multifunctional biointerfaces. Precision photolithography of a modified β‐CD was established on a light sensitive tetrazole surface immobilized on a bioinspired polydopamine (PDA) anchor layer via various shadow masks, as well as via direct laser writing (DLW), in order to craft any desired printboard design. Interfacial molecular recognition provided by light generated cavitate domains was demonstrated via spatially resolved encoding, erasing, and recoding of distinct supramolecular guest patterns. Thus, the light directed shaping of receptor monolayers introduces a powerful path to control supramolecular assemblies on various surfaces.  相似文献   
976.
977.
Russian Journal of Organic Chemistry - Chalcone reacted with acetylene in a suspension of KOH in DMSO at 90°C (30 min) to give 36% of 2-methyl-3,5-diphenylfuran.  相似文献   
978.
Different mean field homogenization methods are applied to a short glass fiber reinforced polybutylene terephthalate. The different models' predictions for the anisotropic effective elastic properties are assessed and compared to experimental data from tensile tests. Additionally, the estimation of fiber stresses and the influence of the fiber length distribution is studied. (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
979.
The one-dimensional turbulence model (ODT) is applied to study turbulent asymptotic suction boundary layers for a Reynolds number of Re = u/v0 = 333, where u and v0 are the free stream and suction velocity, respectively. In here we will demonstrate that a large eddy suppression mechanism may reduce the influence of ODT model parameters, such as the viscous cut-off parameter Z. (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
980.
We investigate the Frobenius number, genus, type, and minimal presentation of a class of numerical semigroups of embedding dimension 4 of the form \(S = \langle a_1, a_2, a_3, a_4 \rangle \) such that \(a_1 + a_4 = a_2 + a_3\). The investigation focuses on determining the Apery set of S with respect to the multiplicity.  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