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   518155篇
  免费   5150篇
  国内免费   1550篇
化学   263992篇
晶体学   6279篇
力学   23604篇
综合类   10篇
数学   73966篇
物理学   157004篇
  2021年   3450篇
  2020年   3846篇
  2019年   4321篇
  2018年   12663篇
  2017年   13083篇
  2016年   11510篇
  2015年   5852篇
  2014年   7898篇
  2013年   20270篇
  2012年   18541篇
  2011年   28337篇
  2010年   18174篇
  2009年   18031篇
  2008年   25420篇
  2007年   28362篇
  2006年   15970篇
  2005年   19858篇
  2004年   15600篇
  2003年   14360篇
  2002年   12477篇
  2001年   12296篇
  2000年   9771篇
  1999年   7281篇
  1998年   6240篇
  1997年   6273篇
  1996年   5886篇
  1995年   5189篇
  1994年   5082篇
  1993年   5164篇
  1992年   5584篇
  1991年   5613篇
  1990年   5328篇
  1989年   5270篇
  1988年   5266篇
  1987年   5113篇
  1986年   4901篇
  1985年   6557篇
  1984年   6951篇
  1983年   5650篇
  1982年   6190篇
  1981年   5989篇
  1980年   5667篇
  1979年   5947篇
  1978年   6278篇
  1977年   6072篇
  1976年   6271篇
  1975年   5726篇
  1974年   5749篇
  1973年   6253篇
  1972年   3976篇
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
11.
Meccanica - In this work we study, from the numerical point of view, a one-dimensional thermoelastic problem where the thermal law is of type III. Quasi-static microvoids are also assumed within...  相似文献   
12.
Aequationes mathematicae - In this paper, we establish a new class of dynamic inequalities of Hardy’s type which generalize and improve some recent results given in the literature. More...  相似文献   
13.
Russian Journal of Applied Chemistry - Recent achievements in the field of the development of preparation methods and study of structure and properties of epoxy nanocomposites with metal-containing...  相似文献   
14.
Russian Journal of Applied Chemistry - A method for the disposal of hydrolysis lignin waste based on its modification with ZnCl2 and FeCl3 and subsequent carbonization at 800°C was proposed....  相似文献   
15.
Low-flow chromatography has a rich history of innovation but has yet to reach widespread implementation in bioanalytical applications. Improvements in pump technology, microfluidic connections, and nano-electrospray sources for MS have laid the groundwork for broader application, and innovation in this space has accelerated in recent years. This article reviews the instrumentation used for nano-flow LC, the types of columns employed, and strategies for multidimensionality of separations, which are key to the future state of the technique to the high-throughput needs of modern bioanalysis. An update of the current applications where nano-LC is widely used, such as proteomics and metabolomics, is discussed. But the trend toward biopharmaceutical development of increasingly complex, targeted, and potent therapeutics for the safe treatment of disease drives the need for ultimate selectivity and sensitivity of our analytical platforms for targeted quantitation in a regulated space. The selectivity needs are best addressed by mass spectrometric detection, especially at high resolutions, and exquisite sensitivity is provided by nano-electrospray ionization as the technology continues to evolve into an accessible, robust, and easy-to-use platform.  相似文献   
16.
Numerical Algorithms - In this work, we propose a fractional extension of the one-dimensional nonlinear vibration problem on an elastic string. The fractional problem is governed by a hyperbolic...  相似文献   
17.
Crystallography Reports - Membrane proteins, including ion channels, became the focus of structural proteomics midway through the 20th century. Methods for studying ion channels are diverse and...  相似文献   
18.
Acta Mathematica Hungarica - Minkowski’s classical existence theorem provides necessary and sufficient conditions for a Borel measure on the unit sphere of Euclidean space to be the surface...  相似文献   
19.
Optics and Spectroscopy - Optical investigations of crystals of solid solutions NdxGd1 – xCr3(BO3)4, 0.01 ≤ x ≤ 1, have been performed. Absorption spectra in the...  相似文献   
20.
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   
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