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   6175篇
  免费   166篇
  国内免费   358篇
化学   3012篇
晶体学   8篇
力学   83篇
综合类   25篇
数学   2119篇
物理学   1452篇
  2023年   33篇
  2022年   119篇
  2021年   124篇
  2020年   119篇
  2019年   78篇
  2018年   91篇
  2017年   107篇
  2016年   112篇
  2015年   72篇
  2014年   90篇
  2013年   313篇
  2012年   174篇
  2011年   369篇
  2010年   272篇
  2009年   521篇
  2008年   474篇
  2007年   408篇
  2006年   452篇
  2005年   303篇
  2004年   205篇
  2003年   157篇
  2002年   1005篇
  2001年   278篇
  2000年   147篇
  1999年   105篇
  1998年   109篇
  1997年   68篇
  1996年   90篇
  1995年   56篇
  1994年   37篇
  1993年   14篇
  1992年   19篇
  1991年   19篇
  1990年   7篇
  1989年   9篇
  1988年   5篇
  1987年   15篇
  1986年   15篇
  1985年   16篇
  1984年   16篇
  1983年   16篇
  1982年   10篇
  1981年   10篇
  1980年   7篇
  1979年   8篇
  1978年   5篇
  1977年   3篇
  1975年   3篇
  1974年   2篇
  1973年   6篇
排序方式: 共有6699条查询结果,搜索用时 15 毫秒
1.
Photoelectrochemical (PEC) cytosensors, a combination of the PEC process and the living-cell assay, have emerged as a powerful tool in the analytical and biological science. This mini review provides a brief introduction of this arena and summaries the key steps about the development of PEC cytosensors with representative examples, followed by future prospects based on our own opinions.  相似文献   
2.
利用分步傅里叶法数值模拟了飞秒孤子在光纤中的传输演化过程。对光纤中单个孤子的传输及二阶孤子的自陡峭效应和自频移效应进行了分析,指出在一定的参数取值范围内,自频移效应对二阶fs孤子传输的影响要比自陡峭效应大,占主导地位,且对自陡峭效应有一定的抑制作用。  相似文献   
3.
Summary In [6], we introduced and investigated the notions of strong β-I-open sets and strong β-I-continuous functions in ideal topological spaces. In this paper, we investigate further their important properties.  相似文献   
4.
The conditions for achievement of high resolving power of depth selective conversion electron Mössbauer spectroscopy method at a combined installation ‘electron spectrometer–nuclear gamma-resonance spectrometer’ have been obtained. There has been made a considerable step in development of the method at its realization at a magnetic sector electron spectrometer with double focusing, equipped with electron source (a sample under investigation) of large-area and position-sensitive detector. The paper presents a prospective symmetrical version of a magnetic sector electron spectrometer that allows realizing more completely possibilities of the method. It is noted that the proposed method is particularly valuable for investigations of nanosystems, nanostrutures that contain Mössbauer nuclei.  相似文献   
5.

A colourless quartz crystal doped with 57Fe3+ was obtained by hydrothermal synthesis in an NH4F solution. The crystal was transformed into violet amethyst by gamma-irradiation. The change in colour was accompanied by changes in the Mössbauer spectrum that can be interpreted as the conversion of trivalent iron into the tetravalent state: Fe3+→Fe4+.

  相似文献   
6.
微全分析系统检测方法的研究进展   总被引:2,自引:0,他引:2  
许春丽  李保新  章竹君 《分析化学》2003,31(12):1520-1526
综述了不同类型的检测方法在微全分析系统的应用,并简述了各类型的检测方法的优缺点。引用文献92篇。  相似文献   
7.
8.
A new scheme for controlling photodissociation through preparation of a variationally optimized linear superposition of field free vibrational eigenstates is applied for selective control of IBr and HI dissociation. The dependence of photodissociation on various field parameters and initial conditions is examined to investigate the mechanistic basis of selective control. The parametric equations of motion approach for determining vibrational dynamics as a function of field parameters without having to solve the time dependent Schrödinger equation explicitly for each field parameter separately is outlined and its use to identify field characteristics which will provide the requisite population mix represented by the optimal linear superposition of vibrational states is advocated.  相似文献   
9.
An effective residual interaction between particles and holes for shell model calculations around 208Pb, derived from the interaction between free nucleons, is compared with the measured properties of proton-hole neutron states in 208Tl and the interaction between proton holes is adjusted to newly measured level energies in 206Hg. These interaction elements are particularly relevant for neutron-rich nuclei. The adjustment of two mixing elements reproduces the known γ-decay data in 208Tl. Received: 2 April 2002 / Accepted: 2 May 2002  相似文献   
10.
We present the recent experimental results on the 6He structure studied by the 6Li(t, 3He)6He reaction at 336 MeV. Above the conspicuous peaks for ground and first excited states for 6He, we have observed a broad structures at E x∼ 5 MeV, and E x∼ 15 MeV. The angular distribution of this structure exhibits the dominance of a ΔL = 1 transition, indicating the existence of intruder dipole states at low excitation energies in 6He. A slight admixture of positive-parity states in this structure has been indicated as well. Received: 1 May 2001 / Accepted: 4 December 2001  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