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   5483篇
  免费   372篇
  国内免费   139篇
化学   4156篇
晶体学   64篇
力学   178篇
综合类   8篇
数学   492篇
物理学   1096篇
  2023年   47篇
  2022年   148篇
  2021年   147篇
  2020年   131篇
  2019年   142篇
  2018年   115篇
  2017年   117篇
  2016年   223篇
  2015年   194篇
  2014年   257篇
  2013年   359篇
  2012年   511篇
  2011年   509篇
  2010年   320篇
  2009年   263篇
  2008年   359篇
  2007年   319篇
  2006年   304篇
  2005年   253篇
  2004年   211篇
  2003年   179篇
  2002年   162篇
  2001年   90篇
  2000年   90篇
  1999年   58篇
  1998年   45篇
  1997年   38篇
  1996年   38篇
  1995年   43篇
  1994年   22篇
  1993年   35篇
  1992年   26篇
  1991年   28篇
  1990年   15篇
  1989年   18篇
  1988年   8篇
  1987年   13篇
  1986年   14篇
  1985年   14篇
  1984年   8篇
  1983年   18篇
  1982年   11篇
  1981年   10篇
  1980年   6篇
  1979年   6篇
  1978年   11篇
  1977年   8篇
  1976年   11篇
  1974年   8篇
  1973年   10篇
排序方式: 共有5994条查询结果,搜索用时 15 毫秒
1.
Zhan  Yang  Dang  Chuangyin 《Mathematical Programming》2021,190(1-2):585-613
Mathematical Programming - In the general equilibrium with incomplete asset markets (GEI) model, the excess demand functions are typically not continuous at the prices for which the assets have...  相似文献   
2.
3.
Journal of Statistical Physics - In this paper, we will study the long time behavior of the simple symmetric exclusion process in the “channel” $$\varLambda _N=[1,N]\cap \mathbb {N}$$...  相似文献   
4.
5.
6.
7.
A new time-domain numerical method is presented for the estimation of noise reduction by the diffraction and finite impedance of barriers. High order finite difference schemes conventionally used for computational aeroacoustics, and time-domain impedance boundary conditions are utilized for the development of the time-domain method. Compared with other methods, this method can be applied more easily to the problems related to nonlinear noise propagation such as impulsive noise and broadband noise. Linearized Euler equations in Cartesian co-ordinates are considered and solved numerically. Straight and T-shaped barriers with and without surface admittance are calculated. In order to assess the accuracy of this time-domain method, comparison with the results of SYSNOISE software (Ver. 5.3) are made. There are very good agreements between the results of the present time-domain numerical method and the boundary element method of the SYSNOISE software.  相似文献   
8.
A (w,r) cover‐free family is a family of subsets of a finite set such that no intersection of w members of the family is covered by a union of r others. A (w,r) superimposed code is the incidence matrix of such a family. Such a family also arises in cryptography as the concept of key distribution pattern. In the present paper, we give some new results on superimposed codes. First we construct superimposed codes from super‐simple designs which give us results better than superimposed codes constructed by other known methods. Next we prove the uniqueness of the (1,2) superimposed code of size 9 × 12, the (2,2) superimposed code of size 14 × 8, and the (2,3) superimposed code of size 30 × 10. Finally, we improve numerical values of upper bounds for the asymptotic rate of some (w,r) superimposed codes. © 2004 Wiley Periodicals, Inc.  相似文献   
9.
Stereoselective synthesis of (+)-lauthisan has been accomplished starting from d-glyceraldehyde acetonide by combination of diastereoselective alkylation and ring-closing metathesis. High degree of 1,3-asymmetric induction has been realized in ether system.  相似文献   
10.
A signal registration strategy from micropatterned immunosensors that converts antigen-antibody binding reactions into electrochemical signals was demonstrated. An array-type micropatterned gold electrode on a silicon wafer was fabricated, containing two electrode geometries of rectangular (100 microm x 500 microm) and circular (r. 50 microm) types, exhibiting electrochemical characteristics of bulk and micro-electrodes, respectively. Ferritin was employed as a model analyte for immunosensing because it has an advantageous molecular structure for functionalization to the sensing interface, and is regarded as a general marker protein for tumors and cancer recurrence. With the fabricated and ferritin-functionalized immunosensors, biospecific interactions were performed with antiferritin antiserum and secondary antibody samples, followed by electrochemical signaling via an immunoprecipitation reaction by the label enzyme. Under the optimized affinity-surface construction steps and reaction conditions, both types of microfabricated electrodes exhibited well-defined calibration results as a function of the protein concentration in antiserum samples. Furthermore, circular-type micropatterned immunoelectrodes exhibited voltammetric characteristics of microelectrodes, which is advantageous in terms of sensor operation under a fixed potential and low signal drift during the signaling reaction compared with the bulk-type electrodes. The results support that the employed signaling method with the proposed immunosensor configuration is fit for sensor miniaturization and integration to future biomicrosystems.  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