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   101500篇
  免费   19978篇
  国内免费   10165篇
化学   85991篇
晶体学   1244篇
力学   4897篇
综合类   721篇
数学   10191篇
物理学   28599篇
  2024年   144篇
  2023年   1196篇
  2022年   1548篇
  2021年   2288篇
  2020年   3560篇
  2019年   4717篇
  2018年   3061篇
  2017年   2565篇
  2016年   6090篇
  2015年   6296篇
  2014年   6892篇
  2013年   8629篇
  2012年   8609篇
  2011年   8267篇
  2010年   6989篇
  2009年   6874篇
  2008年   6885篇
  2007年   5888篇
  2006年   5450篇
  2005年   4756篇
  2004年   4105篇
  2003年   3519篇
  2002年   4200篇
  2001年   3212篇
  2000年   2966篇
  1999年   1949篇
  1998年   1359篇
  1997年   1256篇
  1996年   1223篇
  1995年   1105篇
  1994年   981篇
  1993年   815篇
  1992年   811篇
  1991年   632篇
  1990年   564篇
  1989年   450篇
  1988年   334篇
  1987年   300篇
  1986年   262篇
  1985年   259篇
  1984年   168篇
  1983年   127篇
  1982年   105篇
  1981年   70篇
  1980年   39篇
  1979年   21篇
  1978年   13篇
  1977年   14篇
  1975年   11篇
  1957年   11篇
排序方式: 共有10000条查询结果,搜索用时 38 毫秒
1.
2.
Research on Chemical Intermediates - Owing to the simultaneous utilization of photogenerated electrons and holes, coupling light-driven hydrogen (H2) evolution reaction (HER) and biomass-derived...  相似文献   
3.
Zhang  Bing  Yang  Jie-qin  Liu  Ying  Hu  Bin  Yang  Yang  Zhao  Li  Lu  Qiang 《Cellulose (London, England)》2022,29(12):6565-6578
Cellulose - Heating is essential in various biomass pre-treatments and thermal conversion processes. It is of practical significance to study the characteristics of cellulose-lignin and...  相似文献   
4.
Refractory wounds have always been an important issue to healthcare systems, whose healing process is always delayed by multiple factors, including bacterial infections, chronic inflammation, and excessive exudates, etc. Employing multifunctional wound dressings is recognized as an effective strategy to deal with refractory wounds, which has yielded promising outcomes in recent years. Among these advanced wound dressings, fibrous dressings have gained growing attention due to their unique merits. Such wound dressings have demonstrated great potential in delivering theranostic agents, such as antibacterial agents, anti-inflammatory drugs, growth factors, and diagnostic probes, etc., for the purposes of accelerating wound healing. This paper reviews the development of multifunctional fibrous dressings and their applications in treating refractory wounds. The construction approaches of novel fibrous dressing with capabilities of antibacterial, anti-inflammation, exudate management and diagnosis were also introduced. Furthermore, the existing problems and challenges are also discussed briefly.  相似文献   
5.
Xu  Feixiang  Luo  Jiangchen  Jiang  Liqun  Zhao  Zengli 《Cellulose (London, England)》2022,29(3):1463-1472
Cellulose - In this research, the production of levoglucosan (LG) and levoglucosenone (LGO) was improved from acid-impregnated cellulose via fast pyrolysis. Thermogravimetric and kinetic analysis...  相似文献   
6.
Zhang  Junyu  Hong  Mingyi  Zhang  Shuzhong 《Mathematical Programming》2022,194(1-2):901-935
Mathematical Programming - In this paper, we study the lower iteration complexity bounds for finding the saddle point of a strongly convex and strongly concave saddle point problem: $$\min _x\max...  相似文献   
7.
Three nonfused ring electron acceptors (NFREAs) TTC6,TT-C8T and TT-TC8 were purposefully designed and synthesized.The molecular geometry can be adjusted by the steric hindrance of lateral substituents.According to the DFT calculations,from TTC6 to TT-C8T and TT-TC8,planarity of the molecular backbone is gradually improved,accompanying with the enhancing of intramolecular charge transfer effect.As for TT-TC8,the two phenyl substituents are almost perpendicular to the molecular backbone,which endues the acceptor with good solubility and suppresses it to form over-aggregation.Multidirectional regular molecular orientation and closer molecular stacking are formed in TT-TC8 film.As a result,TT-TC8 based devices afford the highest PCE of 13.13%,which is much higher than that of TTC6 (4.41%) and TT-C8T (10.42%) and among the highest PCE values based on NFREAs.  相似文献   
8.
Wang  Rong  Li  Xu  Zhou  Youshi  Cao  Shuxuan  Xu  Honghao  Han  Wenjuan  Zhang  Yuxia  Liu  Junhai 《Journal of Russian Laser Research》2022,43(4):476-481
Journal of Russian Laser Research - We demonstrate a passively-mode-locked Pr3+: LuLiF4 laser operated at the 604 nm orange wave-length, using monolayer graphene as a saturable absorber. The...  相似文献   
9.
10.
International Journal of Theoretical Physics - This paper mainly studied the observer design of Lipschitz stochastic discrete system. For the first time, generalized Lipschitz conditions are...  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