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   568167篇
  免费   6495篇
  国内免费   1317篇
化学   295184篇
晶体学   7798篇
力学   27378篇
综合类   20篇
数学   74757篇
物理学   170842篇
  2021年   5474篇
  2020年   6077篇
  2019年   6807篇
  2018年   9306篇
  2017年   9256篇
  2016年   12969篇
  2015年   7410篇
  2014年   11662篇
  2013年   26075篇
  2012年   21237篇
  2011年   24784篇
  2010年   18191篇
  2009年   17725篇
  2008年   23166篇
  2007年   23025篇
  2006年   20874篇
  2005年   18748篇
  2004年   17317篇
  2003年   15450篇
  2002年   15147篇
  2001年   15352篇
  2000年   11888篇
  1999年   9148篇
  1998年   7898篇
  1997年   7745篇
  1996年   7318篇
  1995年   6496篇
  1994年   6554篇
  1993年   6324篇
  1992年   6684篇
  1991年   7129篇
  1990年   6807篇
  1989年   6702篇
  1988年   6502篇
  1987年   6314篇
  1986年   6022篇
  1985年   7711篇
  1984年   8027篇
  1983年   6714篇
  1982年   7073篇
  1981年   6566篇
  1980年   6232篇
  1979年   6688篇
  1978年   6947篇
  1977年   6793篇
  1976年   6795篇
  1975年   6485篇
  1974年   6320篇
  1973年   6606篇
  1972年   4787篇
排序方式: 共有10000条查询结果,搜索用时 593 毫秒
181.
182.
Russian Journal of General Chemistry - A method was developed for the synthesis of an organofluorine derivative of β-D-ribofuranoside. Biological tests revealed high insecticidal activity and...  相似文献   
183.
Journal of Thermal Analysis and Calorimetry - In this paper, the variation of thermophysical properties such as the thermal conductivity, thermal energy storage capacity, viscosity, and phase...  相似文献   
184.
This study compares the physicochemical properties of six electrolytes comprising of three salts: LiFTFSI, NaFTFSI and KFTFSI in two solvent mixtures, the binary (3EC/7EMC) and the ternary (EC/PC/3DMC). The transport properties (conductivity, viscosity) as a function of temperature and concentration were modeled using the extended Jones-Dole-Kaminsky equation, the Arrhenius model, and the Eyring theory of transition state for activated complexes. Results are discussed in terms of ionicity, solvation shell, and cross-interactions between electrolyte components. The application of the six formulated electrolytes in symmetrical activated carbon (AC)//AC supercapacitors (SCs) was characterized by cyclic voltammetry (CV), galvanostatic cycling with potential limitation (GCPL), electrochemical impedance spectroscopy (EIS) and accelerated aging. Results revealed that the geometrical flexibility of the FTFSI anion allows it to access and diffuse easily in AC whereas its counter ions (Li+, Na+ or K+) can remain trapped in porosity. However, this drawback was partially resolved by mixing LiFTFSI and KFTFSI salts in the electrolyte.  相似文献   
185.
Journal of Analytical Chemistry - Studies on the separation of the Se and Te trace components from Co, Ni, Cu, Fe, Cr, Mo, and W macrocomponents for their determination by inductively coupled...  相似文献   
186.
ABSTRACT

The authors present the results of an investigation in Fe–Ni-Cr austenitic alloys of the low-temperature deformation-induced segregations of nickel that form in the micro regions being (i) located close to grain- and subgrain boundaries and (ii) characteristic of the concentration and magnetic inhomogeneities indicated by the appearance of a dark diffraction contrast at the electron diffraction patterns taken from these regions typical (at the same time) of an enhanced value of Curie temperature. The observed effects were connected with the micro distortions caused by the local change of lattice parameter because of an increase in nickel concentration, as well as in the result of a magnetostriction dilatation. Using methods of the X-ray energy dispersive spectroscopy (XEDS) and atomic-probe body-section radiography (tomography – APT) has made it possible to determine the borders of those regions of austenite that were characteristic of an enhanced concentration of nickel in the fields of the localisation of a deformation-induced segregation of nickel in the vicinity of grain (subgrain) boundaries of austenitic alloys of the types Fe–13Cr–30Ni and Fe–37Ni–3Ti.  相似文献   
187.
High-energy assisted extraction techniques, like ultrasound assisted extraction (UAE) and microwave assisted extraction (MAE), are widely applied over the last years for the recovery of bioactive compounds such as carotenoids, antioxidants and phenols from foods, animals and herbal natural sources. Especially for the case of xanthophylls, the main carotenoid group of crustaceans, they can be extracted in a rapid and quantitative way with the use of UAE and MAE.  相似文献   
188.
Molecular dynamics simulation was performed to study the formation of cluster structure, interfaces, and surfaces with different curvature radii in a perfect nanocrystal passed through by a nonlinear wave. It is shown that this process is a type of nanostructure self-organization in response to an external energy flux with subsequent development of a strong rotational field.  相似文献   
189.
Shinkorenko  A. S. 《JETP Letters》2022,116(10):759-759
JETP Letters - An Erratum to this paper has been published: https://doi.org/10.1134/S0021364022400028  相似文献   
190.
Molecular Diversity - Hypertension is a medical condition that affects millions of people worldwide. Despite the high efficacy of the current antihypertensive drugs, they are associated with...  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