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   47726篇
  免费   4029篇
  国内免费   3038篇
化学   27630篇
晶体学   700篇
力学   2479篇
综合类   239篇
数学   6371篇
物理学   17374篇
  2024年   56篇
  2023年   466篇
  2022年   847篇
  2021年   1153篇
  2020年   1293篇
  2019年   1489篇
  2018年   1780篇
  2017年   1886篇
  2016年   2377篇
  2015年   1635篇
  2014年   2427篇
  2013年   3269篇
  2012年   3622篇
  2011年   3785篇
  2010年   3329篇
  2009年   3064篇
  2008年   3274篇
  2007年   3034篇
  2006年   2760篇
  2005年   2001篇
  2004年   1482篇
  2003年   1143篇
  2002年   1191篇
  2001年   1008篇
  2000年   1089篇
  1999年   832篇
  1998年   815篇
  1997年   759篇
  1996年   475篇
  1995年   338篇
  1994年   284篇
  1993年   198篇
  1992年   217篇
  1991年   216篇
  1990年   181篇
  1989年   150篇
  1988年   98篇
  1987年   89篇
  1986年   91篇
  1985年   76篇
  1984年   64篇
  1983年   57篇
  1982年   38篇
  1981年   39篇
  1980年   34篇
  1978年   27篇
  1977年   29篇
  1976年   23篇
  1974年   23篇
  1973年   26篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Differential Equations - For a spectrally controllable linear autonomous system with incommensurable delays, we construct a dynamic state feedback in the form of a differential-difference...  相似文献   
3.
Van’kov  A. B.  Kukushkin  I. V. 《JETP Letters》2021,113(2):102-114
JETP Letters - Extraordinary multiparticle effects in quantizing magnetic fields that are manifested in strongly interacting two-dimensional electron systems in MgZnO/ZnO heterostructures have been...  相似文献   
4.
Crystallography Reports - The crystal and molecular structures of Cl–C6H4–O–C16H33 (I) have been studied, and its differential scanning calorimetry (DSC) study is performed....  相似文献   
5.
Crystallography Reports - Two LiInSe2 single crystals, grown under different conditions, have been studied. Characteristics of these crystals for neutron detection have been compared using...  相似文献   
6.
Journal of Radioanalytical and Nuclear Chemistry - The simplified 8-oxide system (SiO2-B2O3-Na2O-Al2O3-CaO-TiO2-MoO3-La2O3) has been prepared under two types of cooling methods, and analyzed with...  相似文献   
7.
Given their superior penetration depths, photosensitizers with longer absorption wavelengths present broader application prospects in photodynamic therapy (PDT). Herein, Ag2S quantum dots were discovered, for the first time, to be capable of killing tumor cells through the photodynamic route by near-infrared light irradiation, which means relatively less excitation of the probe compared with traditional photosensitizers absorbing short wavelengths. On modification with polydopamine (PDA), PDA-Ag2S was obtained, which showed outstanding capacity for inducing reactive oxygen species (increased by 1.69 times). With the addition of PDA, Ag2S had more opportunities to react with surrounding O2, which was demonstrated by typical triplet electron spin resonance (ESR) analysis. Furthermore, the PDT effects of Ag2S and PDA-Ag2S achieved at longer wavelengths were almost identical to the effects produced at 660 nm, which was proved by studies in vitro. PDA-Ag2S showed distinctly better therapeutic effects than Ag2S in experiments in vivo, which further validated the enhanced regulatory effect of PDA. Altogether, a new photosensitizer with longer absorption wavelength was developed by using the hitherto-unexplored photodynamic function of Ag2S quantum dots, which extended and enhanced the regulatory effect originating from PDA.  相似文献   
8.
9.
Cavitation erosion is caused in solids exposed to strong pressure waves developing in an adjacent fluid field. The knowledge of the transient distribution of stresses in the solid is important to understand the cause of damaging by comparisons with breaking points of the material. The modeling of this problem requires the coupling of the models for the fluid and the solid. For this purpose, we use a strategy based on the solution of coupled Riemann problems that has been originally developed for the coupling of 2 fluids. This concept is exemplified for the coupling of a linear elastic structure with an ideal gas. The coupling procedure relies on the solution of a nonlinear equation. Existence and uniqueness of the solution is proven. The coupling conditions are validated by means of quasi‐1D problems for which an explicit solution can be determined. For a more realistic scenario, a 2D application is considered where in a compressible single fluid, a hot gas bubble at low pressure collapses in a cold gas at high pressure near an adjacent structure.  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