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   263387篇
  免费   19836篇
  国内免费   10282篇
化学   155157篇
晶体学   3043篇
力学   13966篇
综合类   489篇
数学   29090篇
物理学   91760篇
  2023年   2386篇
  2022年   2589篇
  2021年   4043篇
  2020年   5255篇
  2019年   5127篇
  2018年   4534篇
  2017年   4284篇
  2016年   7258篇
  2015年   6546篇
  2014年   8165篇
  2013年   15094篇
  2012年   15217篇
  2011年   17335篇
  2010年   11114篇
  2009年   10967篇
  2008年   13589篇
  2007年   12994篇
  2006年   12173篇
  2005年   10760篇
  2004年   8943篇
  2003年   7423篇
  2002年   6631篇
  2001年   7487篇
  2000年   5759篇
  1999年   5006篇
  1998年   4032篇
  1997年   3964篇
  1996年   4047篇
  1995年   3608篇
  1994年   3481篇
  1993年   3038篇
  1992年   3274篇
  1991年   3161篇
  1990年   2700篇
  1989年   2455篇
  1988年   2367篇
  1987年   2187篇
  1986年   2100篇
  1985年   2964篇
  1984年   2871篇
  1983年   2283篇
  1982年   2461篇
  1981年   2327篇
  1980年   2250篇
  1979年   2185篇
  1978年   2246篇
  1977年   2203篇
  1976年   2145篇
  1975年   2127篇
  1973年   2109篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Annals of the Institute of Statistical Mathematics - In this paper, a model averaging approach is developed for the linear regression models with response missing at random. It is shown that the...  相似文献   
2.
Wang  Xigui  Ruan  Jiafu  Wang  Yongmei  Ji  Shue  An  Siyuan 《Meccanica》2021,56(2):303-316
Meccanica - In gear pair actual alternating meshing process, the comprehensive errors of the transmission system and the thermal elastic deformation of the teeth body cause the gears in the meshing...  相似文献   
3.
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   
4.
In this study, the synthesis of TaN nanosheets and their application in theranostic agents is reported. After coating polyethylene glycol (PEG) on the TaN nanosheets, the as-synthesized PEG-modified TaN nanosheets (TaN-PEG) show good stability and biocompatibility. Because of their high absorbance in the near-IR region, TaN-PEG can be utilized as photoacoustic imaging contrast agents for tumor imaging. Moreover, TaN-PEG has significant photothermal conversion performance, exhibiting effective laser-induced tumor ablation capability. The TaN-PEG possessing excellent photoacoustic contrast effect and photothermal properties thus have great promise in theranostic applications, especially imaging-guided cancer treatment.  相似文献   
5.
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   
6.
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   
7.
Wang  Xuebin  Xu  Can  Zheng  Zhigang 《Nonlinear dynamics》2021,103(3):2721-2732
Nonlinear Dynamics - The classical Kuramoto model serves as a useful tool for studying synchronization transitions in coupled oscillators that is limited to the sinusoidal and pairwise...  相似文献   
8.
Wang  Guowei  Ge  Mengyan  Lu  Lulu  Jia  Ya  Zhao  Yunjie 《Nonlinear dynamics》2021,103(3):2627-2643
Nonlinear Dynamics - The hybrid neural model provides a computationally effective and biophysics-based neuron behavior model, which maintains its simplicity by incorporating the dynamics...  相似文献   
9.
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   
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