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   1311篇
  免费   51篇
  国内免费   12篇
化学   959篇
晶体学   29篇
力学   9篇
数学   110篇
物理学   267篇
  2022年   7篇
  2021年   12篇
  2020年   20篇
  2019年   27篇
  2018年   16篇
  2017年   8篇
  2016年   34篇
  2015年   33篇
  2014年   23篇
  2013年   52篇
  2012年   54篇
  2011年   94篇
  2010年   40篇
  2009年   40篇
  2008年   73篇
  2007年   75篇
  2006年   73篇
  2005年   54篇
  2004年   71篇
  2003年   52篇
  2002年   41篇
  2001年   50篇
  2000年   28篇
  1999年   30篇
  1998年   19篇
  1997年   13篇
  1996年   18篇
  1995年   12篇
  1994年   9篇
  1993年   11篇
  1992年   12篇
  1991年   14篇
  1990年   16篇
  1989年   12篇
  1988年   14篇
  1987年   22篇
  1986年   12篇
  1985年   23篇
  1984年   15篇
  1983年   14篇
  1982年   11篇
  1981年   11篇
  1980年   8篇
  1979年   12篇
  1977年   8篇
  1976年   12篇
  1975年   12篇
  1974年   8篇
  1969年   5篇
  1967年   6篇
排序方式: 共有1374条查询结果,搜索用时 15 毫秒
1.
Infection of hosts by morbilliviruses is facilitated by the interaction between viral hemagglutinin (H-protein) and the signaling lymphocytic activation molecule (SLAM). Recently, the functional importance of the n-terminal region of human SLAM as a measles virus receptor was demonstrated. However, the functional roles of this region in the infection process by other morbilliviruses and host range determination remain unknown, partly because this region is highly flexible, which has hampered accurate structure determination of this region by X-ray crystallography. In this study, we analyzed the interaction between the H-protein from canine distemper virus (CDV-H) and SLAMs by a computational chemistry approach. Molecular dynamics simulations and fragment molecular orbital analysis demonstrated that the unique His28 in the N-terminal region of SLAM from Macaca is a key determinant that enables the formation of a stable interaction with CDV-H, providing a basis for CDV infection in Macaca. The computational chemistry approach presented should enable the determination of molecular interactions involving regions of proteins that are difficult to predict from crystal structures because of their high flexibility.  相似文献   
2.
This paper deals with the Cauchy–Dirichlet problem for the fractional Cahn–Hilliard equation. The main results consist of global (in time) existence of weak solutions, characterization of parabolic smoothing effects (implying under proper condition eventual boundedness of trajectories), and convergence of each solution to a (single) equilibrium. In particular, to prove the convergence result, a variant of the so-called ?ojasiewicz–Simon inequality is provided for the fractional Dirichlet Laplacian and (possibly) non-analytic (but C1) nonlinearities.  相似文献   
3.
We study the relation between the cohomology of general linear and symmetric groups and their respective quantizations, using Schur algebras and standard homological techniques to build appropriate spectral sequences. As our methods fit inside a much more general context within the theory of finite-dimensional algebras, we develop our results first in that general setting, and then specialize to the above situations. From this we obtain new proofs of several known results in modular representation theory of symmetric groups. Moreover, we reduce certain questions about computing extensions for symmetric groups and Hecke algebras to questions about extensions for general linear groups and their quantizations.  相似文献   
4.
5.
Taking into account pseudoscalar as well as scalar condensates, we reexamine the chiral restoration path on the chiral manifold. We shall see both condensates coherently produce a density wave at a certain density, which delays chiral restoration as density or temperature is increased.  相似文献   
6.
A convergent synthetic strategy for abietane diterpenoids via B-alkyl Suzuki-Miyaura coupling and Lewis acid-mediated cyclization reactions is established. Asymmetric total synthesis of 12-deoxyroyleanone, an antileishmanial diterpene, is described.  相似文献   
7.
A 10-Gbit/s optical receiver is developed using low-capacitance HBT IC technology. The HBT allows a cutoff frequency of 45 GHz and a maximum oscillation frequency of 70 GHz. The receiver contains an automatic gain-control amplifier IC with a gain of 16 dB, a bandwidth of 10.7 GHz, and a decision-circuit IC with an ambiguity of 66 mVp-p at a data rate of 10 Gbit/s. The sensitivity of this receiver is -26.5 dBm at a bit error rate of 10-9. Transmission over a 140-km fiber was achieved successfully.  相似文献   
8.
The super chamber, a separated UHV reaction-chamber system has been developed. A conversion efficiency of 11.7% was obtained for an a-Si solar cell using a high-quality i-layer deposited by the super chamber, and a p-layer fabricated by a photo-CVD method.As a new material, amorphous superlattice-structure films were fabricated by the photo-CVD method for the first time. Superlattice structure p-layer a-Si solar cells were fabricated, and a conversion efficiency of 10.5% was obtained.For the fabrication of integrated type a-Si solar cell modules, a laser pattering method was investigated. A thermal analysis of the multilayer structure was done. It was confirmed that selective scribing for a-Si, TCO and metal film is possible by controlling the laser power density. Recently developed a-Si solar power generation systems and a-Si solar cell roofing tiles are also described.  相似文献   
9.
This paper presents a simple chaotic circuit consisting of two capacitors, one linear two-port VCCS and one time-state-controlled impulsive switch. The impulsive switch causes rich chaotic and periodic behavior. The circuit dynamics can be simplified into a one-dimensional return map that is piecewise linear and piecewise monotone. Using the return map, we clarify parameter conditions for existence of chaotic and periodic attractors and coexistence state of attractors.  相似文献   
10.
Total synthesis of cordiaquinone K, a new antifungal and larvicidal meroterpenoid, is reported. The absolute configuration of cordiaquinone K was confirmed by the synthesis.  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