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   1809篇
  免费   48篇
  国内免费   14篇
化学   1149篇
晶体学   8篇
力学   54篇
数学   263篇
物理学   397篇
  2023年   11篇
  2022年   14篇
  2021年   14篇
  2020年   28篇
  2019年   30篇
  2018年   19篇
  2017年   14篇
  2016年   34篇
  2015年   31篇
  2014年   36篇
  2013年   77篇
  2012年   81篇
  2011年   95篇
  2010年   59篇
  2009年   51篇
  2008年   83篇
  2007年   99篇
  2006年   98篇
  2005年   93篇
  2004年   80篇
  2003年   67篇
  2002年   48篇
  2001年   23篇
  2000年   24篇
  1999年   26篇
  1998年   19篇
  1997年   14篇
  1996年   16篇
  1995年   11篇
  1994年   17篇
  1993年   11篇
  1992年   19篇
  1991年   16篇
  1990年   14篇
  1985年   30篇
  1984年   27篇
  1983年   23篇
  1982年   37篇
  1981年   34篇
  1980年   21篇
  1979年   12篇
  1978年   20篇
  1977年   11篇
  1976年   21篇
  1975年   21篇
  1974年   17篇
  1973年   16篇
  1972年   10篇
  1971年   9篇
  1965年   9篇
排序方式: 共有1871条查询结果,搜索用时 62 毫秒
1.
The influenza virus is a global threat to human health causing unpredictable yet recurring pandemics, the last four emerging over the course of a hundred years. As our knowledge of influenza virus evolution, distribution, and transmission has increased, paths to pandemic preparedness have become apparent. In the 1950s, the World Health Organization (WHO) established a global influenza surveillance network that is now composed of institutions in 122 member states. This and other surveillance networks monitor circulating influenza strains in humans and animal reservoirs and are primed to detect influenza strains with pandemic potential. Both the United States Centers for Disease Control and Prevention and the WHO have also developed pandemic risk assessment tools that evaluate specific aspects of emerging influenza strains to develop a systematic process of determining research and funding priorities according to the risk of emergence and potential impact. Here, we review the history of influenza pandemic preparedness and the current state of preparedness, and we propose additional measures for improvement. We also comment on the intersection between the influenza pandemic preparedness network and the current SARS-CoV-2 crisis. We must continually evaluate and revise our risk assessment and pandemic preparedness plans and incorporate new information gathered from research and global crises.Subject terms: Influenza virus, Infectious diseases  相似文献   
2.
3.
We derive an appropriate definition of transpose for quaternionic matrices and give a new panoramic review of the quaternionic groups. We aim to analyze possible quaternionic groups for GUTs.  相似文献   
4.
5.
The flat voltage noise component of current biased, high-transparency Nb/AlOx/Nb superconducting tunnel junctions has been investigated at frequencies up to 70 kHz. Several aspects of the analyzed phenomena suggest the presence of current noise effects induced by the discreteness of the charge carriers. At subgap voltages, where excess currents occur, a behavior coherent with a multiple Andreev reflection-assisted transport through the tunnel barrier has been found. However, the measured charge values exceed any theoretical prediction.  相似文献   
6.
We prove existence and uniqueness of integral curves to the (discontinuous) vector field that results when a Lipschitz continuous vector field on a Hilbert space of any dimension is projected on a non-empty, closed and convex subset.

  相似文献   

7.
An approach called Schramm–Loewner evolution (SLE) provides a new method for dealing with a wide variety of scale-invariant problems in two dimensions. This approach is based upon an older method called Loewner Evolution (LE), which connects analytic and geometrical constructions in the complex plane. In this paper, the bases of LE and SLE are described and some simple applications are discussed in relatively non-technical form. A bibliography of the subject is presented.  相似文献   
8.
9.
10.
We show by an almost elementary calculation that the ADM mass of an asymptotically flat space can be computed as a limit involving a rate of change of area of a closed 2-surface. The result is essentially the same as that given by David Brown and York (Phys. Rev. D 55, 1977–1984 1997; Phys. Rev. D 47, 1407–1419 1993). We will prove this result in two ways, first by direct calculation from the original formula as given by Arnowitt, Deser and Misner and second as a corollary of an earlier result by Brewin for the case of simplicial spaces.  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