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   374729篇
  免费   5776篇
  国内免费   2438篇
化学   208826篇
晶体学   6528篇
力学   15758篇
综合类   110篇
数学   37539篇
物理学   114182篇
  2019年   3260篇
  2018年   3631篇
  2017年   3689篇
  2016年   5905篇
  2015年   4058篇
  2014年   6174篇
  2013年   16520篇
  2012年   11820篇
  2011年   14470篇
  2010年   10000篇
  2009年   9965篇
  2008年   12869篇
  2007年   12836篇
  2006年   12191篇
  2005年   11045篇
  2004年   10024篇
  2003年   9046篇
  2002年   8693篇
  2001年   10737篇
  2000年   8254篇
  1999年   6553篇
  1998年   5317篇
  1997年   5210篇
  1996年   5085篇
  1995年   4727篇
  1994年   4558篇
  1993年   4238篇
  1992年   5207篇
  1991年   5013篇
  1990年   4890篇
  1989年   4862篇
  1988年   4834篇
  1987年   4881篇
  1986年   4605篇
  1985年   6034篇
  1984年   6051篇
  1983年   4884篇
  1982年   5158篇
  1981年   5182篇
  1980年   4877篇
  1979年   5269篇
  1978年   5500篇
  1977年   5459篇
  1976年   5238篇
  1975年   4874篇
  1974年   4804篇
  1973年   4796篇
  1972年   3229篇
  1968年   3378篇
  1967年   3456篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
82.
Journal of Thermal Analysis and Calorimetry - Over the last few decades, tremendous consideration is drawn towards corrugation surfaces because of their advantages over the improvement in thermal...  相似文献   
83.
ABSTRACT

The authors present the results of an investigation in Fe–Ni-Cr austenitic alloys of the low-temperature deformation-induced segregations of nickel that form in the micro regions being (i) located close to grain- and subgrain boundaries and (ii) characteristic of the concentration and magnetic inhomogeneities indicated by the appearance of a dark diffraction contrast at the electron diffraction patterns taken from these regions typical (at the same time) of an enhanced value of Curie temperature. The observed effects were connected with the micro distortions caused by the local change of lattice parameter because of an increase in nickel concentration, as well as in the result of a magnetostriction dilatation. Using methods of the X-ray energy dispersive spectroscopy (XEDS) and atomic-probe body-section radiography (tomography – APT) has made it possible to determine the borders of those regions of austenite that were characteristic of an enhanced concentration of nickel in the fields of the localisation of a deformation-induced segregation of nickel in the vicinity of grain (subgrain) boundaries of austenitic alloys of the types Fe–13Cr–30Ni and Fe–37Ni–3Ti.  相似文献   
84.
85.
86.
87.
88.
Shanin  A. V.  Korolkov  A. I.  Kniazeva  K. S. 《Acoustical Physics》2022,68(4):316-325
Acoustical Physics - The problem of pulsed excitation of an acoustic waveguide with a constant cross section is considered. Absorption is ignored. As the most general model of such a waveguide,...  相似文献   
89.
Exosomes are nanovesicles secreted by most cellular types that carry important biochemical compounds throughout the body with different purposes, playing a preponderant role in cellular communication. Because of their structure, physicochemical properties and stability, recent studies are focusing in their use as nanocarriers for different therapeutic compounds for the treatment of different diseases ranging from cancer to Parkinson's disease. However, current bioseparation protocols and methodologies are selected based on the final exosome application or intended use and present both advantages and disadvantages when compared among them. In this context, this review aims to present the most important technologies available for exosome isolation while discussing their advantages and disadvantages and the possibilities of being combined with other strategies. This is critical since the development of novel exosome‐based therapeutic strategies will be constrained to the effectiveness and yield of the selected downstream purification methodologies for which a thorough understanding of the available technological resources is needed.  相似文献   
90.
Xu  H. J.  Zhang  Q. G.  Debenest  G. 《Transport in Porous Media》2021,140(3):625-627
Transport in Porous Media - The theme of coupling problems for adsorption, absorption and thermochemical transport in porous media is very important for engineering applications. Based on the...  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