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   2328篇
  免费   62篇
  国内免费   11篇
化学   1720篇
晶体学   36篇
力学   24篇
数学   92篇
物理学   529篇
  2021年   19篇
  2020年   14篇
  2019年   20篇
  2018年   29篇
  2017年   23篇
  2016年   47篇
  2015年   30篇
  2014年   33篇
  2013年   103篇
  2012年   111篇
  2011年   111篇
  2010年   78篇
  2009年   65篇
  2008年   129篇
  2007年   114篇
  2006年   128篇
  2005年   127篇
  2004年   126篇
  2003年   92篇
  2002年   80篇
  2001年   76篇
  2000年   47篇
  1999年   37篇
  1998年   28篇
  1997年   32篇
  1996年   40篇
  1995年   27篇
  1994年   21篇
  1993年   25篇
  1992年   36篇
  1991年   33篇
  1990年   26篇
  1989年   20篇
  1988年   28篇
  1987年   22篇
  1986年   28篇
  1985年   40篇
  1984年   40篇
  1983年   40篇
  1982年   20篇
  1981年   25篇
  1980年   17篇
  1979年   30篇
  1978年   22篇
  1977年   20篇
  1976年   22篇
  1975年   23篇
  1974年   9篇
  1973年   13篇
  1967年   12篇
排序方式: 共有2401条查询结果,搜索用时 15 毫秒
1.
A facile synthetic strategy towards conformationally stable chiral chromophores based on dimeric porphyrinoids has been established. A peculiar class of face-to-face intramolecularly interlocked corrole dimers were formed by the oxidative C−C coupling linked at the inner carbon sites upon simple treatment of copper(II) ions. Their intrinsic electronic structures were modulated by the peripheral corrole ring annulations, which lead to distinct optical properties and redox profiles. The stereogenic carbon centers implemented in the confused corrole skeleton provided a rationale for designing novel chiral materials.  相似文献   
2.
3.
Tetraoctylammonium cation forms a room-temperature molten salt (RTMS) with 2,4,6-trinitrophenolate anion. The RTMS is immiscible with water (W) and forms a stable RTMS/W interface. It has been shown that the RTMS/W interface can be electrochemically polarized. A well-defined voltammetric wave due to the transfer of thiocyanate ion across the RTMS/W interface was observed within the potential window. This is the first example of a polarized RTMS/W interface.  相似文献   
4.
5.
In order to widely spread out particle beams utilized in cancer therapy, laser-produced ions are developed as the injection beam for an ion synchrotron dedicated for cancer therapy. Such a laser ion source is expected to contribute largely to the realization of compactness of the size and low cost of the cancer therapy accelerator. The energy spectrum of the laser-produced ions, however, has no peak, but their intensities decrease exponentially according to the increase of the energy. For the purpose of modifying such a situation, we have proposed a scheme to rotate the beam in the longitudinal phase space with the use of the RF electric field, which is phase-adjusted with the pulse laser. We aim for a reduction of the energy spread of ± 5% selected by an energy analyzer and slits to ±1% by such phase rotation. For this purpose, a quarter wavelength resonator with two gaps with the same resonant frequency as the source laser has already been fabricated, together with its RF power source. The above phase rotation system and its recent experimental realization are presented.  相似文献   
6.
利用在束γ谱学实验技术, 通过173Yb(19F,4nγ)反应 布居了188Au的高自旋态, 并对其准粒子带结构进行了研究. 基于实验测量结果, 对原有的双奇核188Au能级纲图做了较大的修改. 通过系统性比较, 对15+以上的能级结构进行了讨论.  相似文献   
7.
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   
8.
We compute explicitly the cohomological intersection numbers for the basis and extend the result of Iwasaki and Matsumoto. To this end, we establish the exterior power structure for the polynomial twisted de Rham cohomology group associated with the generalized Airy functions at a point of extended Veronese variety. Using this structure, we introduce a natural basis of the twisted de Rham cohomology group coming from that of the one-dimensional case, which is considered as an analogue of a flat basis of the Jacobi ring of A-type simple singularity.  相似文献   
9.
10.
The oxygen storage capacity of CeO2, Ce0.9Pr0.1O2, Pt?Rh/CeO2 and Pt?Rh/Ce0.9Pr0.1O2 was investigated by conventional GC pulse method and transient pulse techniques. It is shown that incorporation of PrOy into CeO2 matrix strongly promotes oxygen storage capacity (OSC) measured using the transient pulse technique. The improvement of OSC at low temperature is observed in Pt?Rh loaded onto CeO2 and Ce?Pr catalysts.  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