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   364573篇
  免费   4332篇
  国内免费   1099篇
化学   165907篇
晶体学   4211篇
力学   20474篇
综合类   7篇
数学   73446篇
物理学   105959篇
  2021年   1351篇
  2020年   1694篇
  2019年   1693篇
  2018年   18841篇
  2017年   19381篇
  2016年   12200篇
  2015年   4679篇
  2014年   4041篇
  2013年   10565篇
  2012年   16107篇
  2011年   30593篇
  2010年   17964篇
  2009年   18147篇
  2008年   25078篇
  2007年   30045篇
  2006年   9611篇
  2005年   16883篇
  2004年   12511篇
  2003年   11516篇
  2002年   8148篇
  2001年   6803篇
  2000年   5322篇
  1999年   3715篇
  1998年   2833篇
  1997年   2790篇
  1996年   2983篇
  1995年   2631篇
  1994年   2549篇
  1993年   2421篇
  1992年   2721篇
  1991年   2634篇
  1990年   2359篇
  1989年   2324篇
  1988年   2336篇
  1987年   2259篇
  1986年   2133篇
  1985年   3172篇
  1984年   3141篇
  1983年   2500篇
  1982年   2746篇
  1981年   2611篇
  1980年   2565篇
  1979年   2519篇
  1978年   2588篇
  1977年   2408篇
  1976年   2428篇
  1975年   2382篇
  1974年   2276篇
  1973年   2400篇
  1972年   1329篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
1.
Crystallography Reports - Exposure to environmental arsenic is associated with serious of health issues such as cancer, diabetes and developmental delays in infants and children. In human liver,...  相似文献   
2.
3.
We give a characterization of the cyclic subgroup separability and weak potency of the fundamental group of a graph of polycyclic-by-finite groups and free-by-finite groups amalgamating edge subgroups of the form × D,where h has infinite order and D is finite.  相似文献   
4.
Gohl  J. A.  Thiele-Sardina  T. C.  Rencheck  M. L.  Erk  K. A.  Davis  C. S. 《Experimental Mechanics》2021,61(7):1209-1213
Background

Peel tests are frequently used to perform measurements of adhesive strength for pressure sensitive adhesive (PSA) tapes. Current lab methodologies for 90° peel tests translate the model substrate orthogonally to the peel direction in order to maintain the peel angle, precluding testing from immovable substrates.

Objective

It was our objective to develop a peel fixture capable of testing temporary pavement marking (TPM) tapes and other PSA tapes from immovable substrates such as roadways surfaces.

Methods

We present a modular peel fixture for conducting peel experiments directly on immovable substrates. The fixture was validated through a series of peel tests on consumer tapes to reproduce the linear width dependence and viscoelastic rate dependence found in traditional peeling setups. To test the capabilities of the fixture, a series of peel tests were conducted with various tapes on controlled surfaces, and a commercial tape on various immovable substrates.

Results

We demonstrate the ability of our fixture to reproduce results reported for traditional peel tests from literature. In addition, we were able to conduct peel tests directly on immovable substrates such as the benchtop.

Conclusions

This fixture shows potential for both traditional peeling tests, and for use in in-situ peel experiments from substrates relevant to the end application of the PSA tape.

  相似文献   
5.
Set-Valued and Variational Analysis - R. Tyrell Rockafellar and his collaborators introduced, in a series of works, new regression modeling methods based on the notion of superquantile (or...  相似文献   
6.

In this paper, we design a Branch and Bound algorithm based on interval arithmetic to address nonconvex robust optimization problems. This algorithm provides the exact global solution of such difficult problems arising in many real life applications. A code was developed in MatLab and was used to solve some robust nonconvex problems with few variables. This first numerical study shows the interest of this approach providing the global solution of such difficult robust nonconvex optimization problems.

  相似文献   
7.
We prove a well-posedness result for two pseudo-parabolic problems, which can be seen as two models for the same electrical conduction phenomenon in heterogeneous media, neglecting the magnetic field. One of the problems is the concentration limit of the other one, when the thickness of the dielectric inclusions goes to zero. The concentrated problem involves a transmission condition through interfaces, which is mediated by a suitable Laplace-Beltrami type equation.  相似文献   
8.
9.
Journal of Applied Spectroscopy - With the COVID-19 outbreak, many challenges are posed before the scientific world to curb this pandemic. The diagnostic testing, treatment, and vaccine development...  相似文献   
10.
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