首页 | 官方网站   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   31637篇
  免费   5856篇
  国内免费   4462篇
数理化   41955篇
  2024年   87篇
  2023年   681篇
  2022年   785篇
  2021年   1182篇
  2020年   1510篇
  2019年   1411篇
  2018年   1221篇
  2017年   1196篇
  2016年   1677篇
  2015年   1670篇
  2014年   1999篇
  2013年   2603篇
  2012年   3002篇
  2011年   3133篇
  2010年   2247篇
  2009年   2009篇
  2008年   2279篇
  2007年   1912篇
  2006年   1688篇
  2005年   1413篇
  2004年   1137篇
  2003年   923篇
  2002年   933篇
  2001年   753篇
  2000年   617篇
  1999年   596篇
  1998年   458篇
  1997年   396篇
  1996年   434篇
  1995年   356篇
  1994年   303篇
  1993年   225篇
  1992年   215篇
  1991年   206篇
  1990年   147篇
  1989年   125篇
  1988年   69篇
  1987年   69篇
  1986年   97篇
  1985年   64篇
  1984年   34篇
  1983年   30篇
  1982年   19篇
  1981年   13篇
  1980年   4篇
  1975年   4篇
  1974年   2篇
  1969年   2篇
  1957年   9篇
  1936年   2篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
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   
2.
3.
Tian  Xiu-Zhi  Yang  Rui  Ma  Jia-Jia  Ni  Yong-Hao  Deng  Hai-Bo  Dai  Lei  Tan  Jiao-Jun  Zhang  Mei-Yun  Jiang  Xue 《高分子科学》2022,40(7):789-798
Chinese Journal of Polymer Science - Antistatic and strength properties are of vital importance for polyurethane rubber used in moving parts of many industrial instruments. Herein, polyurethane was...  相似文献   
4.
5.
International Journal of Theoretical Physics - Quantum coherence, coming from quantum superposition, occupies a significant position in the field of physics. We put forward a lower bound of the...  相似文献   
6.
7.
A graphic sequence π =(d1, d2,..., dn) is said to be forcibly k-edge-connected if every realization of π is k-edge-connected. In this paper, we obtain a new sufficient degree condition for π to be forcibly k-edgeconnected. We also show that this new sufficient degree condition implies a strongest monotone degree condition for π to be forcibly 2-edge-connected and a conjecture about a strongest monotone degree condition for π to be forcibly 3-edge-connected due to...  相似文献   
8.
Gao  Zhigen  Guo  Jianhua  Ma  Yanyuan 《中国科学 数学(英文版)》2021,64(8):1905-1916
Science China Mathematics - Linear factor models are familiar tools used in many fields. Several pioneering literatures established foundational theoretical results of the quasi-maximum likelihood...  相似文献   
9.
10.
We studied the ring opening of propylene oxide (PO) by salen-M coordinated OH group [M = Al(III), Sc(III), Cr(III), Mn(III), Fe(III), Co(II), Co(III), Ni(II), Cu(II), Zn(II), Ru(III) and Rh(III)]. The results show that the ring-opening energy barriers for M(II) complexes are much lower than those with M(III) complexes in the gas phase, and the barriers correlate linearly with the negative charges on the OH group and the Fukui function condensed on the OH group. The nucleophilicity ordering in the gas phase can be rationalized by the ratio of formal positive charges/radius of M cations. Solvent effect greatly increases the barriers of M(II) complexes but slightly changes the results of M(III) ones, making the barriers similar. Analysis indicates that the reaction heats are linearly proportional to the reverse reaction barriers. The relationships established here can be used to estimate the ring-opening barriers and to screen epoxide ring-opening catalysts.  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-23

京公网安备 11010802026262号