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   5563篇
  免费   242篇
  国内免费   43篇
化学   3831篇
晶体学   35篇
力学   136篇
数学   1075篇
物理学   771篇
  2023年   41篇
  2022年   28篇
  2021年   143篇
  2020年   105篇
  2019年   129篇
  2018年   106篇
  2017年   82篇
  2016年   196篇
  2015年   177篇
  2014年   203篇
  2013年   346篇
  2012年   400篇
  2011年   448篇
  2010年   289篇
  2009年   293篇
  2008年   359篇
  2007年   375篇
  2006年   343篇
  2005年   331篇
  2004年   245篇
  2003年   177篇
  2002年   157篇
  2001年   66篇
  2000年   45篇
  1999年   41篇
  1998年   26篇
  1997年   40篇
  1996年   65篇
  1995年   39篇
  1994年   39篇
  1993年   39篇
  1992年   47篇
  1991年   40篇
  1990年   25篇
  1989年   29篇
  1988年   22篇
  1987年   22篇
  1986年   24篇
  1985年   37篇
  1984年   25篇
  1983年   25篇
  1982年   32篇
  1981年   22篇
  1980年   22篇
  1979年   17篇
  1978年   11篇
  1977年   8篇
  1975年   8篇
  1974年   7篇
  1968年   7篇
排序方式: 共有5848条查询结果,搜索用时 15 毫秒
1.
Aequationes mathematicae - For $$p\in (1,\infty )$$ , we establish several criteria of one-sided invertibility on spaces $$l^p=l^p(\mathbb {Z})$$ for discrete band-dominated operators being either...  相似文献   
2.
Meccanica - Fiber reinforced materials are used in assorted engineering application and for this reason, new additive manufacturing technologies have been developed for this type of materials. With...  相似文献   
3.
We propose four new convolutions exhibiting convenient factorization properties associated with two finite interval integral transformations of Fourier-type together with their norm inequalities. Moreover, we study the solvability of a class of integral equations of Wiener-Hopf plus Hankel type (on finite intervals) with the help of the factorization identities of such convolutions. Fourier-type series are used to produce the solution formula of such equations, and a Shannon-type sampling formula is also obtained.  相似文献   
4.
The main goal of this work is to adapt a Physics problem to the Machine Learning (ML) domain and to compare several techniques to solve it. The problem consists of how to perform muon count from the signal registered by particle detectors which record a mix of electromagnetic and muonic signals. Finding a good solution could be a building block on future experiments. After proposing an approach to solve the problem, the experiments show a performance comparison of some popular ML models using two different hadronic models for the test data. The results show that the problem is suitable to be solved using ML as well as how critical the feature selection stage is regarding precision and model complexity.  相似文献   
5.
The objective of this work is to present sufficient conditions for having positive topological entropy for continuous self-maps defined on a closed surface by using the action of this map on the homological groups of the closed surface.  相似文献   
6.
7.
We describe the synthesis and the physical properties of polyaromatic hydrocarbons (PAHs) containing a phosphorus atom at the edge. In particular, the impact of the successive addition of aromatic rings on the electronic properties was investigated by experimental (UV/Vis absorption, fluorescence, cyclic voltammetry) and theoretical studies (DFT). The physical properties recorded in solution and in the solid state showed that the P‐containing PAHs exhibit properties expected for an emitter in white organic light‐emitting diodes (WOLEDs).  相似文献   
8.
9.
10.
The synthesis and self-assembling features of twistacene 1 are reported. The supramolecular polymerization of 1 displays a consecutive pathway to afford slipped ( AggI ) and rotationally displaced ( AggII ) aggregates conditioned by the formation of intramolecularly H-bonded pseudocycles. In methylcyclohexane, both AggI and AggII are highly stable and the interconversion of the kinetically controlled AggI into the thermodynamically controlled AggII takes several weeks to occur. The utilization of toluene as solvent changes the energetic level for both aggregates and favors a faster conversion of AggI into AggII within a period of minutes. This conversion can be accelerated by the addition of seeds. Furthermore, concentration dependent kinetic studies demonstrate the consecutive character of the supramolecular polymerization of 1 .  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