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   33943篇
  免费   5865篇
  国内免费   5136篇
数理化   44944篇
  2024年   88篇
  2023年   685篇
  2022年   847篇
  2021年   1174篇
  2020年   1453篇
  2019年   1407篇
  2018年   1211篇
  2017年   1252篇
  2016年   1722篇
  2015年   1731篇
  2014年   2093篇
  2013年   2731篇
  2012年   3235篇
  2011年   3380篇
  2010年   2424篇
  2009年   2225篇
  2008年   2445篇
  2007年   2176篇
  2006年   1960篇
  2005年   1592篇
  2004年   1216篇
  2003年   1015篇
  2002年   1121篇
  2001年   950篇
  2000年   712篇
  1999年   695篇
  1998年   499篇
  1997年   445篇
  1996年   423篇
  1995年   385篇
  1994年   302篇
  1993年   243篇
  1992年   216篇
  1991年   196篇
  1990年   144篇
  1989年   128篇
  1988年   71篇
  1987年   79篇
  1986年   92篇
  1985年   59篇
  1984年   35篇
  1983年   30篇
  1982年   18篇
  1981年   14篇
  1980年   6篇
  1976年   2篇
  1975年   2篇
  1974年   2篇
  1959年   2篇
  1957年   8篇
排序方式: 共有10000条查询结果,搜索用时 531 毫秒
1.
2.
A numerical model was developed and validated to investigate the fluid–structure interactions between fully developed pipe flow and core–shell-structured microcapsule in a microchannel. Different flow rates and microcapsule shell thicknesses were considered. A sixth-order rotational symmetric distribution of von Mises stress over the microcapsule shell can be observed on the microcapsule with a thinner shell configuration, especially at higher flow rate conditions. It is also observed that when being carried along in a fully developed pipe flow, the microcapsule with a thinner shell tends to accumulate stress at a higher rate compared to that with a thicker shell. In general, for the same microcapsule configuration, higher flow velocity would induce a higher stress level over the microcapsule shell. The deformation gradient was used to capture the microcapsule's deformation in the present study. The effect of Young's modulus on the microcapsule shell on the microcapsule deformation was investigated as well. Our findings will shed light on the understanding of the stability of core–shell-structured microcapsule when subjected to flow-induced shear stress in a microfluidic system, enabling a more exquisite control over the breakup dynamics of drug-loaded microcapsule for biomedical applications.  相似文献   
3.
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   
4.
International Journal of Theoretical Physics - The Majorana representation, which provides an intuitive way to represent the quantum state by stars on the Bloch sphere, has drawn considerable...  相似文献   
5.
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   
6.
In the paper, the authors establish several integral representations for the generating functions of the large and little Schröder numbers and for the large and little Schröder numbers.  相似文献   
7.
8.
9.
Journal of Sol-Gel Science and Technology - A novel gas sensing material, La–Y co-doped TiO2 nanoparticles, was synthesized by sol–gel method and applied to detect organic pollutants...  相似文献   
10.
In this communication, we report the synthesis of small‐sized (<10 nm), water‐soluble, magnetic nanoparticles (MNPs) coated with polyhedral oligomeric silsesquioxanes (POSS), which contain either polyethylene glycol (PEG) or octa(tetramethylammonium) (OctaTMA) as functional groups. The POSS‐coated MNPs exhibit superparamagnetic behavior with saturation magnetic moments (51–53 emu g?1) comparable to silica‐coated MNPs. They also provide good colloidal stability at different pH and salt concentrations, and low cytotoxicity to MCF‐7 human breast epithelial cells. The relaxivity data and magnetic resonance (MR) phantom images demonstrate the potential application of these MNPs in bioimaging.  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