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   1671篇
  免费   27篇
  国内免费   6篇
化学   904篇
晶体学   10篇
力学   37篇
数学   173篇
物理学   456篇
无线电   124篇
  2020年   14篇
  2019年   12篇
  2017年   12篇
  2016年   25篇
  2015年   15篇
  2014年   31篇
  2013年   50篇
  2012年   59篇
  2011年   73篇
  2010年   47篇
  2009年   36篇
  2008年   73篇
  2007年   65篇
  2006年   68篇
  2005年   60篇
  2004年   39篇
  2003年   55篇
  2002年   58篇
  2001年   47篇
  2000年   40篇
  1999年   34篇
  1998年   27篇
  1997年   33篇
  1996年   28篇
  1995年   35篇
  1994年   32篇
  1993年   31篇
  1992年   33篇
  1991年   19篇
  1990年   28篇
  1989年   25篇
  1988年   25篇
  1987年   21篇
  1986年   24篇
  1985年   31篇
  1984年   18篇
  1983年   22篇
  1982年   29篇
  1981年   19篇
  1980年   35篇
  1979年   18篇
  1978年   21篇
  1977年   19篇
  1976年   17篇
  1975年   19篇
  1974年   25篇
  1973年   16篇
  1971年   9篇
  1970年   10篇
  1969年   9篇
排序方式: 共有1704条查询结果,搜索用时 15 毫秒
141.
142.
143.
144.
The IMPAD technique has been used to determine the Larmor precessions of the83Y 595 keV 13/2+ and 145 keV 7/2+ states in iron. The net precessions found are ωτ(13/2+)=−9(2) mrad and ωτ(7/2+)=−92(5) mrad, leading to g-factors, g(13/2+)=+1.3(4) and g(7/2+)=+0.61(18). These results are discussed in terms of a partially decoupled [422]5/2+ Nilsson band.  相似文献   
145.
Electronic transport properties are presented for the three lowest-energy conformers of the chrysazine molecule. The current–voltage characteristics of these isomers are calculated for two different connections of the molecule to gold leads. The results for the various structures differ so significantly from each other that the specific conformer and its connection to the leads can be identified by its transport characteristics. The calculated transport properties suggest that chrysazine may be used as a molecular optical switch.  相似文献   
146.
The first asymmetric total synthesis of fumimycin was accomplished. As a key step, a 1,2-addition of methyl Grignard reagents to ketimines with quinine as additive was employed. The absolute configuration of (+)-fumimycin was determined by CD-spectroscopy combined with time-dependent density functional calculations.  相似文献   
147.
Invasive aspergillosis caused by the mould Aspergillus fumigatus is a life‐threatening lung or systemic infection in the immunocompromised host. In this study, a protective immune response against the disease was achieved in two infected rabbits, and the cellular fungal antigenic proteome that mediated such a response was investigated against the background of vaccine development efforts. Altogether, 59 different Aspergillus proteins were found becoming reactive in the course of the developing immunity, many of which are described in this context for the first time. These included proteins related to oxidative stress management, glycolysis and other metabolic pathways. As oxidative stress is suspected to be one of the major defense mechanisms, the results may indicate at least in part a continuous response of the pathogen to evade the host's immune system. In addition, proteins with suspected cell surface association or crucial function for fungal cell development were identified. As these antigens are newly recognized during the process of the developing immunoprotection, they may not only represent valuable infection markers but also importantly broaden the list of possible vaccine candidates.  相似文献   
148.
The potential and application of X‐ray absorption spectroscopy (XAS) for structural investigations of organic–inorganic hybrid materials, with a special emphasis on systems consisting of inorganic building blocks (clusters) embedded into polymer backbones, is extensively reviewed. In the first part of the paper, the main features of organic–inorganic hybrid materials, their classification, the synthetic approaches for their preparation, and their applications are concisely presented, whereas the particular issues related to their characterization are discussed in more detail. In the second section of the paper, the principles and the theoretical background of the XAS method, including experimental design, data reduction, evaluation, analysis, and interpretation are described and discussed. Examples of potentialities of the method for the short‐range structural investigation of inorganic nanostructures in hybrids are provided, and the state‐of‐the‐art in the field of hybrid materials is reviewed. In the third part, six different case studies belonging to our past and present experience in this field are presented and discussed, with a particular focus on their XAS investigation.  相似文献   
149.
Given some observable H on a finite-dimensional quantum system, we investigate the typical properties of random state vectors \({|\psi\rangle}\) that have a fixed expectation value \({\langle\psi|H|\psi\rangle=E}\) with respect to H. Under some conditions on the spectrum, we prove that this manifold of quantum states shows a concentration of measure phenomenon: any continuous function on this set is almost everywhere close to its mean. We also give a method to estimate the corresponding expectation values analytically, and we prove a formula for the typical reduced density matrix in the case that H is a sum of local observables. We discuss the implications of our results as new proof tools in quantum information theory and to study phenomena in quantum statistical mechanics. As a by-product, we derive a method to sample the resulting distribution numerically, which generalizes the well-known Gaussian method to draw random states from the sphere.  相似文献   
150.
We systematically measured the dc voltage V(ISH) induced by spin pumping together with the inverse spin Hall effect in ferromagnet-platinum bilayer films. In all our samples, comprising ferromagnetic 3d transition metals, Heusler compounds, ferrite spinel oxides, and magnetic semiconductors, V(ISH) invariably has the same polarity, and scales with the magnetization precession cone angle. These findings, together with the spin mixing conductance derived from the experimental data, quantitatively corroborate the present theoretical understanding of spin pumping in combination with the inverse spin Hall effect.  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