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   140975篇
  免费   15682篇
  国内免费   7463篇
化学   100244篇
晶体学   1750篇
力学   6729篇
综合类   498篇
数学   14991篇
物理学   39908篇
  2023年   942篇
  2022年   2144篇
  2021年   2623篇
  2020年   3789篇
  2019年   5163篇
  2018年   4124篇
  2017年   3782篇
  2016年   7003篇
  2015年   6077篇
  2014年   7133篇
  2013年   9375篇
  2012年   8596篇
  2011年   8215篇
  2010年   7491篇
  2009年   7458篇
  2008年   7368篇
  2007年   6398篇
  2006年   5689篇
  2005年   5331篇
  2004年   4699篇
  2003年   4241篇
  2002年   4992篇
  2001年   4085篇
  2000年   3412篇
  1999年   2157篇
  1998年   1751篇
  1997年   1527篇
  1996年   1462篇
  1995年   1224篇
  1994年   1280篇
  1993年   1210篇
  1992年   1173篇
  1991年   1219篇
  1990年   1185篇
  1989年   1088篇
  1988年   955篇
  1987年   951篇
  1986年   908篇
  1985年   951篇
  1984年   929篇
  1983年   831篇
  1982年   808篇
  1979年   805篇
  1978年   813篇
  1977年   808篇
  1976年   919篇
  1975年   815篇
  1974年   849篇
  1973年   848篇
  1972年   752篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Single crystals and polycrystals of titanium diselenide TiSe2 intercalated with ferrocene Fe(η5-C5H5)2 and cobaltocene Co(η5-C5H5)2 are synthesized. The magnetic susceptibility and electrical resistivity of the intercalation compounds are measured. The results obtained demonstrate that the intercalation brings about the formation of an impurity band with a temperature-dependent width.  相似文献   
992.
The formation of a molybdenum reflecting coating with a columnar nanocrystalline structure is studied under the condition when molybdenum is deposited by dc magnetron sputtering on single-crystalline molybdenum mirrors (substrates). The coating is found to peel off together with a polishing-induced imperfect amorphous surface layer of the substrate. This effect aids in obtaining a free mirror-like molybdenum foil. When the amorphous imperfect layer is removed from the substrate before deposition, the reflecting mirror coating has a good adhesion to the substrate.  相似文献   
993.
Kinetic features of radical polymerization of styrene initiated by tert-butyl perbenzoate in the presence of tris(N,N-dimethyldithiocarbamato)cobalt(III) (CoL3) and its adduct with iodine (CoL3 · 2I2) were studied. The optimal concentration ratios of the activators and tert-butyl perbenzoate, providing fast styrene polymerization at 338–368 K, were determined.  相似文献   
994.
995.
Summary Pust' Ej (j =1,2) - lokal'no vypuklye prostranstva funktsii, odnoznachnykh i lokal'no analiticheskikh na nekotorom mnozhestve Q ⊂ℂ. Pust', dalee, m(E1,E2) - mnozhestvo vsekh mul'tiplikatorov pary E1, E2 i L (E1, E2) sovokupnost' vsekh lineinykh operatorov, deistvuyushchikh iz E1 v E2. V stat'e e pri opredelennykh predpolozheniyakh poluchen kriterii predstavleniya operatora T iz L (E1, E2), kommutiruyushchego s fiksirovannym elementom a m(E1,E1) ∩m(E2,E2), v kanonicheskoi forme Ty = b · y, gde bm(E1,E2). Obsuzhdayut·sya predpolozheniya, pri kotorykh poluchen kriterii, i privodyat·sya primery, pokazyvayushchie ikh sushchestvennost'.  相似文献   
996.
We prove analogs of the Telyakovskii-Pochuev criteria for multipliers of uniform convergence and of convergence in the integral metric for multiplicative systems with bounded generating sequence.  相似文献   
997.
Two novel dithienylethenes with ferrocene units were synthesized by Wittig reaction. The structure of 2a has been established by X‐ray diffraction studies. They could reversibly interconvert between two thermally stable forms, an open and a closed one, using light of different wavelengths as triggers. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
998.
The magnetic and magnetoelastic parameters of Fe64Co21B15 and Fe81.5B13.5Si3C2 amorphous ferromagnetic alloys treated by direct electric current in air are studied as functions of the applied magnetic field and current density. The samples of the alloy have the form of narrow strips with different lengths. It is found that the magnetoelastic parameters of the dc-treated alloys depend on the magnetic field in a qualitatively different way. From the behavior of the magnetic and magnetoelastic parameters of the alloys in the magnetic field a model of magnetization nonuniform distribution in amorphous ferromagnetic alloys subjected to dc treatment is proposed.  相似文献   
999.
A direct (without sample pretreatment) atomic-absorption method of V and Ni determination in oil with electrothermal atomization and Zeeman correction of background was developed.  相似文献   
1000.
The possibility of raising the static exchange capacity of strongly acidic ion-exchange materials produced by grafting of styrene onto polypropylene fibers, with the subsequent sulfonation of the products synthesized, was analyzed. The chemical and osmotic stabilities of the sulfonic cation exchangers obtained and their frost resistance in freeze-thaw cycles were studied.  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