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   1583篇
  免费   223篇
  国内免费   171篇
化学   89篇
晶体学   1篇
力学   151篇
综合类   48篇
数学   1445篇
物理学   243篇
  2023年   24篇
  2022年   17篇
  2021年   37篇
  2020年   51篇
  2019年   50篇
  2018年   49篇
  2017年   43篇
  2016年   57篇
  2015年   42篇
  2014年   65篇
  2013年   86篇
  2012年   72篇
  2011年   83篇
  2010年   79篇
  2009年   93篇
  2008年   110篇
  2007年   97篇
  2006年   111篇
  2005年   82篇
  2004年   66篇
  2003年   77篇
  2002年   79篇
  2001年   72篇
  2000年   61篇
  1999年   60篇
  1998年   56篇
  1997年   40篇
  1996年   41篇
  1995年   31篇
  1994年   16篇
  1993年   11篇
  1992年   15篇
  1991年   19篇
  1990年   10篇
  1989年   9篇
  1988年   4篇
  1987年   3篇
  1986年   6篇
  1985年   12篇
  1984年   6篇
  1983年   6篇
  1982年   7篇
  1981年   4篇
  1980年   4篇
  1979年   6篇
  1978年   2篇
  1977年   3篇
  1975年   1篇
  1970年   1篇
  1936年   1篇
排序方式: 共有1977条查询结果,搜索用时 15 毫秒
91.
Microparticle‐based drug delivery is a promising technology for small volume bioassay platforms. The general utilization of the drug‐loaded microparticles in the in vitro bioassay platforms requires the drug loading method, which should impregnate the general drug types (e.g., water insoluble) with high payload into the variously designed microparticles. Loading the drug into the prefabricated microparticles using solvent evaporation satisfies the requirement. However, similar to the “coffee‐ring effect,” drugs are loaded in a seriously nonuniform manner, caused by the capillary flow during the evaporation process. Here, it is presented that the freeze‐drying is an efficient way to load uniform and high amount of the drug into the prefabricated microparticles. It is demonstrated that freezing solvent can block the capillary flow during the solvent removal process, improving the loading uniformity. The delivered amount of drugs is linearly proportional to the initial loading amount of drugs. Also, this drug loading method is shown to be applied to the various drug types and the prefabricated microparticles with different properties. Considering many challenges to suppress the “coffee‐ring effect” that induces nonuniform impregnation/deposition, the proposed concept can be applied not only for microparticle‐based drug delivery but also for uniform coating applications (e.g., thin‐film coating, DNA/protein microarray).  相似文献   
92.
We study the uniform convergence of Walsh-Fourier series of functions on the generalized Wiener class BV (p(n)↑∞) This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   
93.
We investigate the uniform convergence of the density of the empirical measure of an ergodic diffusion. It is known that under certain conditions on the drift and diffusion coefficients of the diffusion, the empirical density f t converges in probability to the invariant density f, uniformly on the entire real line. We show that under the same conditions, uniform convergence of f t to f on compact intervals takes place almost surely. Moreover, we prove that under much milder conditions (the usual linear growth condition on the drift and diffusion coefficients and a finite second moment of the invariant measure suffice), we have the uniform convergence of f t to f on compacta in probability. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   
94.
In this note, we enumerate all nonisomorphic 3‐factorizations of K10. © 2001 John Wiley & Sons, Inc. J Combin Designs 9: 379–383, 2001  相似文献   
95.
This paper reports on a numerical algorithm for the steady flow of viscoelastic fluid. The conservative and constitutive equations are solved using the finite volume method (FVM) with a hybrid scheme for the velocities and first‐order upwind approximation for the viscoelastic stress. A non‐uniform staggered grid system is used. The iterative SIMPLE algorithm is employed to relax the coupled momentum and continuity equations. The non‐linear algebraic equations over the flow domain are solved iteratively by the symmetrical coupled Gauss–Seidel (SCGS) method. In both, the full approximation storage (FAS) multigrid algorithm is used. An Oldroyd‐B fluid model was selected for the calculation. Results are reported for planar 4:1 abrupt contraction at various Weissenberg numbers. The solutions are found to be stable and smooth. The solutions show that at high Weissenberg number the domain must be long enough. The convergence of the method has been verified with grid refinement. All the calculations have been performed on a PC equipped with a Pentium III processor at 550 MHz. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
96.
(7)中给出并研究了均匀设计抽样(UDS)及随机化均匀设计(RUD)的一些优良性质,作者给出该设计和抽样的一、二阶矩。  相似文献   
97.
Randomization time for the overhand shuffle   总被引:1,自引:0,他引:1  
This paper analyzes repeated shuffling of a deck ofN cards. The measure studied is a model for the popularoverhand shuffle introduced by Aldous and Diaconis. It is shown that convergence to the uniform distribution requires at least orderN 2 shuffles, and that orderN 2 log(N) shuffles suffice. For a 52-card deck, more than 1000 shuffles are needed.  相似文献   
98.
Virbhadra  K S  Prasanna  A R 《Pramana》1989,33(4):449-454
We investigate the ratio of spin precession frequency to orbital frequency for a spinning charged particle confined to circular orbit in the equatorial plane of a compact object, with a uniform magnetic field, as described by the Wald and the Ernst potentials. In order to see the difference in behaviours for particles with differentg values we consider the cases of electron and proton separately.  相似文献   
99.
This paper presents an infeasible-interior-point algorithm for a class of nonmonotone complementarity problems, and analyses its convergence and computational complexity. The results indicate that the proposed algorithm is a polynomial-time one.  相似文献   
100.
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