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   203622篇
  免费   3263篇
  国内免费   537篇
化学   112841篇
晶体学   1949篇
力学   7470篇
综合类   12篇
数学   25753篇
物理学   59397篇
  2021年   1640篇
  2020年   1922篇
  2019年   2025篇
  2018年   2524篇
  2017年   2441篇
  2016年   4293篇
  2015年   3115篇
  2014年   3994篇
  2013年   9701篇
  2012年   8220篇
  2011年   9508篇
  2010年   6487篇
  2009年   6264篇
  2008年   8563篇
  2007年   8454篇
  2006年   7833篇
  2005年   7357篇
  2004年   6365篇
  2003年   5445篇
  2002年   4984篇
  2001年   5195篇
  2000年   4125篇
  1999年   3067篇
  1998年   2613篇
  1997年   2585篇
  1996年   2519篇
  1995年   2367篇
  1994年   2416篇
  1993年   2217篇
  1992年   2495篇
  1991年   2521篇
  1990年   2355篇
  1989年   2281篇
  1988年   2209篇
  1987年   2106篇
  1986年   2027篇
  1985年   2629篇
  1984年   2749篇
  1983年   2215篇
  1982年   2395篇
  1981年   2303篇
  1980年   2175篇
  1979年   2303篇
  1978年   2445篇
  1977年   2341篇
  1976年   2368篇
  1975年   2244篇
  1974年   2314篇
  1973年   2319篇
  1972年   1497篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Massoumi  Sina  Challamel  Noël  Lerbet  Jean  Wautier  Antoine  Nicot  François  Darve  Félix 《Meccanica》2022,57(8):2043-2066
Meccanica - This study is an attempt towards a better understanding of the length scale effects on the bending response of the granular beams. To this aim, a unidimensional discrete granular chain...  相似文献   
2.
3.
This work demonstrates the analytical applicability of single ion-selective membranes (ISMs) and potentiometric sensor array to distinguish and detect cathinone derivatives. Potentiometric data from ISMs based on cation exchanger and varying content of calix[4]arene derivative were processed by principal component analysis (PCA). Such a combination of methods allowed discriminating various individual synthetic cathinones and their recognition from the mixture comprising primary amines (substituted amphetamines+aminoindane). Analytical parameters of ISM containing 1wt % of calix[4]arene derivative were sufficient to detect 1.0×10−4 mol.l−1 1-(4-fluorophenyl)-2-(ethylamino)butan-1-one and 2-(methylamino)-1-phenylbutan-1-one (buphedrone) in both model and saliva samples.  相似文献   
4.
This work describes the basic principles of Total-reflection X-Ray Fluorescence (TXRF) spectrometry and some of its most outstanding applications for investigating metal traces, mainly in biological and biomedical samples. TXRF is an analytical technique that combines the versatility of elemental analysis by X-ray energy dispersion with a low detection limit in the order of picograms of absolute mass or a few ppb (μg L−1) as concentration. The microanalytical capacity of TXRF allows the study of small sample quantities. The TXRF can perform qualitative and mass ratio analyses of the elements present in a sample of only a few hundred nanograms. These properties are of great importance in the research of metal traces in biological systems, as they allow fast, precise, and accurate characterisation of the elemental fingerprint at trace level. Its successful application in studies of the coordination kinetics of new platinum-based antitumor drugs with DNA, its application in the study profile of the metal in healthy and cancerous human tissues, or even its application in the study of the processes of metal diffusion through cell membranes are just a few examples of TXRF capabilities in the biomedical sciences. This brief review's main objective is to provide an overview of the physical principles and possibilities of TXRF spectrometry. It also highlights some of the most outstanding applications that have been developed so far, mainly in the biological field, so that the reader can evaluate their potential applications.  相似文献   
5.
Journal of Thermal Analysis and Calorimetry - The paper focuses on the analytical analysis of the propagation of a normal shock wave in an adiabatic gas flow with nanoparticles. A modified...  相似文献   
6.
Journal of Solid State Electrochemistry - The addition of nanocrystalline titanium dioxide (P90) to a cathode of Li/S cell enhances its voltammetric charge capacity by 19%, from which only a small...  相似文献   
7.
The European Physical Journal A - The goal of the present paper is twofold. First, a novel expansion many-body method applicable to superfluid open-shell nuclei, the so-called Bogoliubov in-medium...  相似文献   
8.
Fuzzy Optimization and Decision Making - Cost-allocation problems in a fixed network are concerned with distributing the costs for use by a group of clients who cooperate in order to reduce such...  相似文献   
9.
Journal of Solid State Electrochemistry - UV/Vis absorption spectroelectrochemistry is a very promising analytical technique due to the complementary information that is simultaneously obtained...  相似文献   
10.
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