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   8169篇
  免费   1033篇
  国内免费   549篇
化学   5673篇
晶体学   49篇
力学   418篇
综合类   16篇
数学   1103篇
物理学   2492篇
  2023年   159篇
  2022年   126篇
  2021年   257篇
  2020年   310篇
  2019年   279篇
  2018年   258篇
  2017年   210篇
  2016年   338篇
  2015年   318篇
  2014年   429篇
  2013年   572篇
  2012年   723篇
  2011年   763篇
  2010年   506篇
  2009年   414篇
  2008年   523篇
  2007年   441篇
  2006年   426篇
  2005年   339篇
  2004年   258篇
  2003年   196篇
  2002年   159篇
  2001年   144篇
  2000年   134篇
  1999年   142篇
  1998年   107篇
  1997年   108篇
  1996年   139篇
  1995年   115篇
  1994年   82篇
  1993年   70篇
  1992年   76篇
  1991年   64篇
  1990年   83篇
  1989年   59篇
  1988年   37篇
  1987年   38篇
  1986年   34篇
  1985年   28篇
  1984年   29篇
  1983年   23篇
  1982年   21篇
  1981年   24篇
  1980年   16篇
  1979年   27篇
  1978年   23篇
  1977年   20篇
  1976年   17篇
  1975年   25篇
  1974年   16篇
排序方式: 共有9751条查询结果,搜索用时 250 毫秒
1.
Journal of Optimization Theory and Applications - We consider the conic linear program given by a closed convex cone in an Euclidean space and a matrix, where vector on the right-hand side of the...  相似文献   
2.
3.
Kwak  Do Y.  Park  Hyeokjoo 《Numerical Algorithms》2022,91(1):449-471
Numerical Algorithms - We develop a formal construction of a pointwise divergence-free basis in the nonconforming virtual element method of arbitrary order for the Stokes problem introduced in Zhao...  相似文献   
4.
Journal of Radioanalytical and Nuclear Chemistry - In this study, the halloysite nanotubes was characterized and the adsorption of Th(IV) and U(VI) on halloysite nanotubes was investigated as a...  相似文献   
5.
Monoester‐diterpenoid alkaloids are the main bioactive components of Sini decoction, which is a well‐known traditional Chinese medicine formula for the treatment of myocardial infarction (MI) and heart failure in China. In this work, an ultra‐high‐performance liquid chromatography–mass spectrometry combined with microdialysis method was successfully established and applied for investigating for the first time comparative plasma pharmacokinetics of three monoester‐diterpenoid alkaloids (benzoylmesaconitine, benzoylaconitine and benzoylhypacoitine) in normal and MI rats after oral administration of Sini decoction. The statistical results of pharmacokinetic parameters demonstrated that benzoylmesaconitine, benzoylaconitine and benzoylhypacoitine showed lower peak concentration, longer half‐life, smaller area under the concentration–time curve, slower clearance, time to peak concentration and mean residence time in MI rats than in normal rats (p < 0.05), which indicated that monoester‐diterpenoid alkaloids exhibited lower systemic exposure and slower elimination in the MI rats. The results provided the experimental basis for understanding the metabolic fate and therapeutic effects of Sini decoction.  相似文献   
6.
Zhou  Lili  Tan  Fei 《Nonlinear dynamics》2019,96(2):869-883
Nonlinear Dynamics - In this paper, we mainly propose a chaotic secure communication scheme which is based on the synchronization of double-layered and multiple complex dynamical networks. Compared...  相似文献   
7.
Tan  Pan  Fan  Cuiling  Mesnager  Sihem  Guo  Wei 《Designs, Codes and Cryptography》2022,90(3):681-693
Designs, Codes and Cryptography - For a long time, the literature has demonstrated that designs and codes are exciting topics for combinatorics and coding theory. Linear codes and t-designs are, in...  相似文献   
8.
Nguyen  Duc H.  Lowenberg  Mark H.  Neild  Simon A. 《Nonlinear dynamics》2022,108(2):1179-1196
Nonlinear Dynamics - Based on bifurcation theory, nonlinear frequency response analysis is a recent development in the field of flight dynamics studies. Here, we consider how this method can be...  相似文献   
9.
This review examines the most recent electrochemical developments for nitrate, nitrite and ammonium detection for on-site water monitoring. There remains a high demand for effective field-based detection of the dissolved inorganic nitrogen (DIN) analytes to aid in mitigating nitrogen loading. Electrochemical approaches show increasing potential to fill this role as advancements in nanotechnology continually improve analytical performance and on-site applicability. However, translating these improvements into the field still faces the resonating challenges of reaching analytical proficiency (selectivity, sensitivity, robustness, stability), practical end-user functionality, minimal matrix interferences and cost effectiveness. Herein, we elaborate on these challenges via a critical evaluation of current studies and examine how realistic the prospects of on-site nitrate, nitrite and ammonium are. We also present recommendations in addressing these gaps to conclude the review.  相似文献   
10.
The separation efficiency of charge carriers determines the analytical sensitivity of the paper-based photoelectrochemical sensor. Herein, the Lewis base modification strategy is proposed to promote the carrier separation through an in-situ ion exchange method. Firstly, three-dimensional paper-based hierarchically TiO2 (PHT) arrays are prepared with the one-step hydrothermal method. With the aid of Lewis base, the photo-induced charge separation efficiency and the photocurrent signal are obviously increased. Ultimately, sensitive sensing of prostate specific antigen (PSA) is achieved and the linear range is 1 pg/mL–100 ng/mL with the detection limitation of 0.3 pg/mL.  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