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   179644篇
  免费   18962篇
  国内免费   24795篇
化学   114317篇
晶体学   3703篇
力学   10794篇
综合类   2313篇
数学   23619篇
物理学   68655篇
  2023年   1664篇
  2022年   4308篇
  2021年   4561篇
  2020年   4981篇
  2019年   5223篇
  2018年   5323篇
  2017年   6016篇
  2016年   6510篇
  2015年   6114篇
  2014年   8063篇
  2013年   11075篇
  2012年   11334篇
  2011年   12136篇
  2010年   10332篇
  2009年   10375篇
  2008年   11339篇
  2007年   10647篇
  2006年   9656篇
  2005年   8477篇
  2004年   7096篇
  2003年   5751篇
  2002年   5862篇
  2001年   5417篇
  2000年   4936篇
  1999年   3452篇
  1998年   2685篇
  1997年   2238篇
  1996年   2184篇
  1995年   1945篇
  1994年   2002篇
  1993年   1866篇
  1992年   1765篇
  1991年   1682篇
  1990年   1700篇
  1989年   1575篇
  1988年   1302篇
  1987年   1292篇
  1986年   1191篇
  1985年   1295篇
  1984年   1308篇
  1983年   1092篇
  1982年   1066篇
  1981年   948篇
  1979年   1028篇
  1978年   957篇
  1977年   994篇
  1976年   1085篇
  1975年   942篇
  1974年   968篇
  1973年   969篇
排序方式: 共有10000条查询结果,搜索用时 531 毫秒
11.
Russian Journal of General Chemistry - The review article traces the main trends of the synthetic approach to the solution of the problem of overcoming the resistance of pathogenic bacterial...  相似文献   
12.
Knyazev  Yu. V.  Kazak  N. V.  Gavrichkov  V. A.  Polukeev  S. I.  Ovchinnikov  S. G. 《JETP Letters》2022,116(8):567-573
JETP Letters - Changes in the magnetic properties of FeBO3 single crystals in the course of spin crossover occurring with increasing pressure up to 63 GPa are studied both experimentally and...  相似文献   
13.
14.
Let p ∈ [1, ∞), q ∈ [1, ∞), α∈ R, and s be a non-negative integer. Inspired by the space JNp introduced by John and Nirenberg(1961) and the space B introduced by Bourgain et al.(2015), we introduce a special John-Nirenberg-Campanato space JNcon(p,q,s) over Rn or a given cube of R;with finite side length via congruent subcubes, which are of some amalgam features. The limit space of such spaces as p →∞ is just the Campanato space which coincides with the space BMO(the space of functions with bounded mean oscillations)when α = 0. Moreover, a vanishing subspace of this new space is introduced, and its equivalent characterization is established as well, which is a counterpart of the known characterization for the classical space VMO(the space of functions with vanishing mean oscillations) over Rn or a given cube of Rn with finite side length.Furthermore, some VMO-H1-BMO-type results for this new space are also obtained, which are based on the aforementioned vanishing subspaces and the Hardy-type space defined via congruent cubes in this article. The geometrical properties of both the Euclidean space via its dyadic system and congruent cubes play a key role in the proofs of all these results.  相似文献   
15.
Three nonfused ring electron acceptors (NFREAs) TTC6,TT-C8T and TT-TC8 were purposefully designed and synthesized.The molecular geometry can be adjusted by the steric hindrance of lateral substituents.According to the DFT calculations,from TTC6 to TT-C8T and TT-TC8,planarity of the molecular backbone is gradually improved,accompanying with the enhancing of intramolecular charge transfer effect.As for TT-TC8,the two phenyl substituents are almost perpendicular to the molecular backbone,which endues the acceptor with good solubility and suppresses it to form over-aggregation.Multidirectional regular molecular orientation and closer molecular stacking are formed in TT-TC8 film.As a result,TT-TC8 based devices afford the highest PCE of 13.13%,which is much higher than that of TTC6 (4.41%) and TT-C8T (10.42%) and among the highest PCE values based on NFREAs.  相似文献   
16.
17.
Russian Physics Journal - The temperature dependences of the linear dielectric permittivity ε′ and the third harmonic coefficient γ3ω for nanocomposites obtained by embedding a...  相似文献   
18.
International Journal of Theoretical Physics - In this work, we give an analytical derivation of the reduced density matrix between two qubits in a cavity field, which is described by the quantum...  相似文献   
19.
Technical Physics - Taking damping into account in the problems of structural dynamics is an important and nontrivial problem. Its complexity is primarily determined by the required specification...  相似文献   
20.
Theoretical and Mathematical Physics - We consider three one-dimensional superconducting structures: 1) the one with $$p$$ -wave superconductivity; 2) the main experimental model of a nanowire with...  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