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   1179篇
  免费   34篇
  国内免费   5篇
化学   861篇
晶体学   17篇
力学   19篇
数学   51篇
物理学   270篇
  2023年   6篇
  2022年   11篇
  2021年   13篇
  2020年   17篇
  2019年   19篇
  2018年   15篇
  2016年   25篇
  2015年   15篇
  2014年   23篇
  2013年   57篇
  2012年   55篇
  2011年   88篇
  2010年   39篇
  2009年   37篇
  2008年   76篇
  2007年   82篇
  2006年   96篇
  2005年   80篇
  2004年   75篇
  2003年   52篇
  2002年   72篇
  2001年   14篇
  2000年   18篇
  1999年   19篇
  1998年   10篇
  1997年   10篇
  1996年   11篇
  1995年   22篇
  1994年   10篇
  1993年   6篇
  1992年   7篇
  1991年   9篇
  1990年   4篇
  1989年   8篇
  1988年   16篇
  1987年   8篇
  1986年   6篇
  1985年   10篇
  1984年   12篇
  1983年   7篇
  1982年   3篇
  1981年   8篇
  1980年   7篇
  1979年   10篇
  1978年   6篇
  1977年   3篇
  1976年   2篇
  1975年   4篇
  1974年   8篇
  1973年   3篇
排序方式: 共有1218条查询结果,搜索用时 31 毫秒
1.
2.
We report the recent development on the SUSY calculations with the help of GRACE system. GRACE/SUSY/1LOOP is the computer code which can generate Feynman diagrams in the MSSM automatically and compute one-loop amplitudes in the numerical way. We present new results of various two-body decay widths and chargino pair production at ILC (international linear collider) at one-loop level.   相似文献   
3.
The electrophoresis of DNA chains in uncrosslinked polymer solutions with a Brownian dynamics simulation with an anisotropic friction tensor was analyzed. According to the degree of anisotropy, three types of migration behavior are obtained: fluctuation without or with periodicity between U‐shaped and compact conformations, or migration with linear conformation. We found good agreement between our simulation results and the direct observations of DNA by fluorescence microscopy. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1316–1322, 2003  相似文献   
4.
The oscillation of the interfacial tension and electrical potential at a water/nitrobenzene interface was observed with homologous anionic surfactant molecules, sodium-alkyl-sulfates. Concerning small molecules with a short hydrophobic carbon chain, the oscillation period and amplitude decreased with a decrease of the length of the alkyl chain. On the other hand, when surfactant molecules with a long hydrophobic carbon chain were used, no remarkable periodic oscillation occurred after the first oscillation. In all systems, an interfacial flow by Marangoni convection was observed when the oscillation took place. By monitoring the movement of carbon powder scattered on the liquid/liquid interface with a CCD camera, we could observe that the liquid/liquid interface expanded outward from the area on which the surfactant molecules adsorbed when the oscillation occurred. When the small molecule was used, the speed of expansion of the interface (flow speed) was small and shrinkage followed by expansion of the interface repeatedly occurred. However, when the large molecule was used, the flow speed was large and expansion occurred only one time. These results show that hydrodynamic factors and surface activities are important in chemical oscillation systems.  相似文献   
5.
6.
We demonstrate the potential of femtosecond two-color pulse interferometry for in vitro optical glucose monitoring, by dispersion of the group refractive index in a glucose solution sample with respect to a red-color light and a blue-color light. By comparison with femtosecond one-color pulse interferometry, the basic performance of the present system with regard to sensitivity, quantitativeness, and tolerance to surrounding disturbances, is evaluated. The resulting accuracy and precision of glucose determination are 77 and 118mg/dl for 10-mm-sample-thickness, respectively. This near-common-path configuration of the two-color pulse light provides good stability to fluctuations of sample temperature, which is important in clinical applications. Considering the performance of femtosecond two-color pulse interferometry as an optical glucose sensor, a suitable measurement site for in vivo optical glucose monitoring is discussed.  相似文献   
7.
The effect of the cation concentration, hydrolysis temperature, and composition in the CeO2–ZrO2 system on the direct precipitation of ceria–zirconia solid solutions and the structure of the precipitates from acidic aqueous solutions of (NH4)2Ce(NO3)6 and ZrOCl2 by hydrolysis under hydrothermal conditions were investigated. Nanometer-sized (8–10 nm) ceria–zirconia solid solution particles in a composition range of 0 to 60 mol% ZrO2 were directly precipitated from the solutions with total metal cation concentration less than 0.2 mol/dm3 by simultaneous thermal hydrolysis at 150–240°C. The crystalline phase of the precipitates gradually changed from cubic and/or tetragonal to monoclinic with increasing the cation concentration of the solution from 0.2 to 0.8 mol/dm3 at the starting composition of 50 mol% ZrO2 under hydrolysis condition of 150°C for 48 h, which was attributed to decrease in the supply of hydrolyzed Ce component caused by decrease in the hydrolysis ratio of (NH4)2Ce(NO3)6. Ceria–zirconia solid solutions containing large amount of ZrO2 maintained high specific surface area and small-sized crystallite after heat-treatment at 900–1000°C for 1 h.  相似文献   
8.
Masanori Asakura 《K-Theory》2002,27(3):273-280
We construct 0-cycles on a self-product of a curve whose cycle classes are linearly independent in the extension group of arithmetic Hodge structure. This is an extended version of Theorem 4.5 of Asakura's contribution to CMR Lecture Notes Ser. 24 ((2000), pp. 133–154).  相似文献   
9.
This paper considers two models of BASIC mode data transmission: When we transmit data with length l
1. (1) data are divided into N blocks and each block is transmitted individually
2. (2) data are divided into N sub-blocks and all sub-blocks are transmitted together.
We derive total average transmission data lengths of each model and discuss optimal numbers N* and block length B* which minimize them. In model 1, the length of one block is approximately determined independently of l. It is shown in a numerical example that when l is large, model 2 is better than model 1.  相似文献   
10.
A novel method for synthesizing arylhydrazones, the precursor for Fischer indole synthesis, using aryllithium reagents and α-diazo esters that are easily obtained from α-amino acid esters, is described.  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