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   692篇
  免费   4篇
  国内免费   19篇
化学   192篇
力学   56篇
数学   252篇
物理学   215篇
  2016年   11篇
  2015年   6篇
  2014年   6篇
  2013年   42篇
  2012年   16篇
  2011年   29篇
  2010年   6篇
  2009年   14篇
  2008年   19篇
  2007年   23篇
  2006年   21篇
  2005年   19篇
  2004年   19篇
  2003年   8篇
  2002年   15篇
  2001年   10篇
  2000年   9篇
  1999年   12篇
  1998年   12篇
  1997年   12篇
  1996年   12篇
  1995年   15篇
  1994年   9篇
  1993年   20篇
  1992年   9篇
  1991年   9篇
  1990年   14篇
  1989年   14篇
  1988年   9篇
  1987年   9篇
  1986年   15篇
  1985年   19篇
  1984年   12篇
  1983年   15篇
  1982年   11篇
  1981年   17篇
  1980年   17篇
  1979年   15篇
  1978年   18篇
  1977年   15篇
  1976年   12篇
  1975年   11篇
  1974年   12篇
  1973年   19篇
  1972年   9篇
  1971年   5篇
  1969年   6篇
  1967年   6篇
  1966年   6篇
  1965年   5篇
排序方式: 共有715条查询结果,搜索用时 375 毫秒
71.
In this paper we are concerned about the ways GCH can fail in relation to rank-into-rank hypotheses, i.e., very large cardinals usually denoted by I3, I2, I1 and I0. The main results are a satisfactory analysis of the way the power function can vary on regular cardinals in the presence of rank-into-rank hypotheses and the consistency under I0 of the existence of ${j : V_{\lambda+1} {\prec} V_{\lambda+1}}$ with the failure of GCH at ${\lambda}$ .  相似文献   
72.
We study regularity properties related to Cohen, random, Laver, Miller and Sacks forcing, for sets of real numbers on the \({\varvec{\Delta}^1_3}\) level of the projective hieararchy. For \({\varvec{\Delta}^1_2}\) and \({\varvec{\Sigma}^1_2}\) sets, the relationships between these properties follows the pattern of the well-known Cichoń diagram for cardinal characteristics of the continuum. It is known that assuming suitable large cardinals, the same relationships lift to higher projective levels, but the questions become more challenging without such assumptions. Consequently, all our results are proved on the basis of ZFC alone or ZFC with an inaccessible cardinal. We also prove partial results concerning \({\varvec{\Sigma}^1_3}\) and \({\varvec{\Delta}^1_4}\) sets.  相似文献   
73.
74.
75.
76.
Multiple emission of intermediate-mass fragments has been studied for the collisions p + Au at 2.16, 3.6 and 8.1 GeV with the FASA setup. The mean IMF multiplicities for events with at least one IMF are equal to 1.7, 1.9 and 2.1 (±0.2) respectively. The multiplicity, charge distributions and kinetic energy spectra of IMF are described in the framework of a intranuclear cascade model followed by the statistical multifragmentation model. However, between the two parts of the calculation the excitation energies and the residual masses and charges are modified to take into account the losses during expansion. The results support a scenario of true thermal multifragmentation of a hot and expanded target spectator. Received: 15 December 1997 / Revised version: 24 April 1998  相似文献   
77.
A rank one transformationT was constructed by Chacón that is weakly mixing but not mixing. We will show thatT is lightly mixing, not partially mixing, and not lightly 2-mixing. Partially supported by an NSF Postdoctoral Research Fellowship.  相似文献   
78.
Initiation of apoptosis, or programmed cell death, is an important issue in cancer treatment as cancer cells frequently have acquired the ability to block apoptosis and thus are more resistant to chemotherapeutic drugs. Targeted and perhaps selective destruction of cancerous tissue is desirable for many reasons, ranging from the enhancement of or aid to current medical methods to problems currently lacking a solution, i.e., lung cancer. Demonstrated in this publication is the inactivation (killing) of human Melanoma skin cancer cell lines, in vitro, by Floating Electrode Dielectric Barrier Discharge (FE-DBD) plasma. Not only are these cells shown to be killed immediately by high doses of plasma treatment, but low doses are shown to promote apoptotic behavior as detected by TUNEL staining and subsequent flow cytometry. It is shown that plasma acts on the cells directly and not by “poisoning” the solution surrounding the cells, even through a layer of such solution. Potential mechanisms of interaction of plasma with cells are discussed and further steps are proposed to develop an understanding of such systems.  相似文献   
79.
We wish to construct an optimal optical lens, in the sense that it focuses all rays from a given source onto a given focal point. The construction can be reduced mathematically to a global study of a system of two nonlinear functional differential equations. We prove that this system has precisely two analytic solutions.  相似文献   
80.
A procedure is suggested here for reconstructing the time variation of a three-dimensional (3D) coherent velocity field, based on applying Least Square Method to a very limited number of phase-locked measurements. The measurements are performed in a spanwise plane of a forced turbulent mixing layer by employing the stereo particle image velocimetry system. The forcing is produced by oscillating two- and three-dimensional (3D) flappers placed at the edge of the splitter plate. The feasibility and validity of the procedure for velocity field reconstruction are checked by using Hot Wire Measurements. Very clear patterns are observed of two types of coherent structures: spanwise K-H billows (rolls) and streamwise vortices. These are due to primary and secondary instabilities and their time evolution is presented.  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