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   3287篇
  免费   32篇
  国内免费   82篇
化学   155篇
晶体学   1篇
力学   88篇
综合类   28篇
数学   2869篇
物理学   260篇
  2024年   3篇
  2023年   10篇
  2022年   26篇
  2021年   17篇
  2020年   41篇
  2019年   27篇
  2018年   21篇
  2017年   40篇
  2016年   52篇
  2015年   59篇
  2014年   130篇
  2013年   327篇
  2012年   159篇
  2011年   213篇
  2010年   141篇
  2009年   248篇
  2008年   186篇
  2007年   230篇
  2006年   188篇
  2005年   128篇
  2004年   109篇
  2003年   92篇
  2002年   101篇
  2001年   125篇
  2000年   88篇
  1999年   75篇
  1998年   72篇
  1997年   58篇
  1996年   61篇
  1995年   40篇
  1994年   17篇
  1993年   17篇
  1992年   15篇
  1991年   12篇
  1990年   9篇
  1989年   13篇
  1988年   10篇
  1987年   3篇
  1986年   6篇
  1985年   50篇
  1984年   48篇
  1983年   19篇
  1982年   38篇
  1981年   33篇
  1980年   25篇
  1979年   15篇
  1978年   4篇
排序方式: 共有3401条查询结果,搜索用时 31 毫秒
81.
针对变水量空调系统温度控制的时变、大滞后、非线性特点,结合模糊控制和PID控制,设计了基于模糊规则切换的Fuzzy-PID分级控制器,并在Matlab/Simulink软件上进行了仿真。仿真结果表明,控制器同时具有模糊控制超调量小、鲁棒性好和PID控制精度高、响应速度快的优点。  相似文献   
82.
Let U(g)U(g) be the enveloping algebra of a finite dimensional reductive Lie algebra gg over an algebraically closed field of prime characteristic. Let U?,P(s:)U?,P(s:) be the simply connected quantum enveloping algebra at the root of unity ?  , of a complex semi-simple finite dimensional Lie algebra s:s:. We show, by similar proofs, that the centers of both are factorial. While the first result was established by R. Tange [32] (by different methods), the second one confirms a conjecture in [4]. We also provide a general criterion for the factoriality of the centers of enveloping algebras in prime characteristic.  相似文献   
83.
84.
Tribbles homolog 3 (TRIB3) protein is inhibiting the insulin signaling by directly binding to the Akt/PKB leading to insulin resistance in the pancreas causing type 2 diabetes mellitus. Hence, TRIB3 protein is considered as a possible drug target for the new lead identification against type 2 diabetes. In the present study, the homology model of TRIB3 protein was generated to explore its biochemical function and molecular interactions in the new lead identification. The energy minimization of TRIB3 protein was carried out and evaluated by validation protocols for structure reliability. The druggable binding site of TRIB3 protein was identified for the virtual screening and molecular docking studies. The Asinex-fragments library of 22634 small molecules was docked at TRIB3 active site using the Glide module to identify new chemical entities. A total of 9 molecules were identified as final hits from virtual screening and their potency was ranked using Glide score, Glide energies, and residues interactions. The 6 prioritized lead molecules were further optimized using AutoDock, Prime MM/GBSA, and percentage of human oral absorption for the identification of potential leads. The molecules L2, L5, and L6 are identified as lead inhibitors and are showing consistent interactions with key residues Glu194 and Lys196 of TRIB3 protein. The identified potential leads were analyzed by ADME properties for their drug likeness and HergIC50 values are predicted for the prevention of preclinical failures. The present work sheds light on the identification of the best lead molecules against TRIB3 protein and offers a route to design as novel potential drug candidates for T2DM.  相似文献   
85.
针对新型装甲装备通用质量特性评价指标体系难以确定的问题,在明确评价指标体系构建原则的基础上,结合新型装甲装备特点,确定了通用质量特性初始评价指标及指标筛选要求,运用QFD将新型装甲装备通用质量特性需求映射为评价指标筛选要求,采用粗糙集理论(Rough Set Theory,RST)确定了指标筛选重要度,考虑到关联度的不确定性及多个专家估计值的平均值和估计值的波动程度,将贝叶斯理论引入关系矩阵的确定中,用区间数确定了关联度,进行了评价指标筛选,构建了新型装甲装备通用质量特性评价指标体系,为新型装甲装备通用质量特性评价奠定了基础。  相似文献   
86.
针对航天器真空热试验对数据采集、温度控制及系统功能的要求,设计开发了一套基于LXI总线的分布式测控系统。针对目前控制系统对于温度控制系统大滞后、非线性的控制性能不佳的缺点,采用模糊自整定PID算法提升了当前控制系统的控制品质,实现了对航天器的外热流模拟与温度控制。实际运行结果表明,该系统具有可靠性高、扩展性强、控制精度高等优点,并且试验准备时间比原有系统减少一半以上,提高了试验人员的工作效率。  相似文献   
87.
88.
Infrared polarization and intensity imagery provide complementary and discriminative information in image understanding and interpretation. In this paper, a novel fusion method is proposed by effectively merging the information with various combination rules. It makes use of both low-frequency and high-frequency images components from support value transform (SVT), and applies fuzzy logic in the combination process. Images (both infrared polarization and intensity images) to be fused are firstly decomposed into low-frequency component images and support value image sequences by the SVT. Then the low-frequency component images are combined using a fuzzy combination rule blending three sub-combination methods of (1) region feature maximum, (2) region feature weighting average, and (3) pixel value maximum; and the support value image sequences are merged using a fuzzy combination rule fusing two sub-combination methods of (1) pixel energy maximum and (2) region feature weighting. With the variables of two newly defined features, i.e. the low-frequency difference feature for low-frequency component images and the support-value difference feature for support value image sequences, trapezoidal membership functions are proposed and developed in tuning the fuzzy fusion process. Finally the fused image is obtained by inverse SVT operations. Experimental results of visual inspection and quantitative evaluation both indicate the superiority of the proposed method to its counterparts in image fusion of infrared polarization and intensity images.  相似文献   
89.
90.
模糊逻辑在机器人逆运动学求解中的应用   总被引:2,自引:0,他引:2  
冗余机器人逆运动学求解的方法很多,多数都不能很好的满足实时控制的要求,本文运用模糊逻辑的思想,构造了一种逆运动学求解方法,其计算量较其它方法大大减小,且满足实时控制的要求,仿真结果也证明了该方法的可行性。  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