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   1063篇
  免费   101篇
  国内免费   34篇
化学   34篇
力学   15篇
综合类   8篇
数学   600篇
物理学   541篇
  2023年   11篇
  2022年   21篇
  2021年   26篇
  2020年   40篇
  2019年   32篇
  2018年   29篇
  2017年   32篇
  2016年   27篇
  2015年   30篇
  2014年   69篇
  2013年   109篇
  2012年   42篇
  2011年   60篇
  2010年   32篇
  2009年   57篇
  2008年   68篇
  2007年   60篇
  2006年   54篇
  2005年   71篇
  2004年   65篇
  2003年   54篇
  2002年   30篇
  2001年   23篇
  2000年   36篇
  1999年   16篇
  1998年   21篇
  1997年   5篇
  1996年   6篇
  1995年   13篇
  1994年   4篇
  1993年   6篇
  1992年   8篇
  1991年   4篇
  1990年   3篇
  1989年   10篇
  1988年   8篇
  1987年   1篇
  1986年   3篇
  1985年   3篇
  1984年   2篇
  1983年   1篇
  1982年   1篇
  1978年   1篇
  1977年   2篇
  1975年   1篇
  1970年   1篇
排序方式: 共有1198条查询结果,搜索用时 31 毫秒
971.
Carbon monosulfide was detected in outer space by rovibrational spectroscopy of the X 1Σ+ state and A 1Π – X 1Σ+ system. This work calculated the potential energy curves and dipole moment functions of the X 1Σ+ 0+ and A 1Π1 states, and computed the transition dipole moments between the two states employing the CASSCF method, followed by the valence icMRCI approach. Core-valence correlation and scalar relativistic corrections were included. The extrapolation of potential energies to the complete basis set limit was performed. The spin-orbit coupling effect was included. The Einstein A coefficients, band origins, and oscillator strengths were calculated for the rovibrational transitions when J?≤?150. The rovibrational transitions of the X 1Σ+ 0+ and A 1Π1 states became very weak when Δυ?≥?6. The Einstein A coefficients of vibronic emissions of the A 1Π1 – X 1Σ+ 0+ system were large, indicating that the emissions were able to be measured easily through spectroscopy. Several rovibrational transitions of the A 1Π1 – X 1Σ+ 0+ system were analysed in detail. The distribution of radiative lifetime varying as rotational quantum number was calculated. The results obtained in this work agree well with the available experimental values.  相似文献   
972.
In this paper,we discuss the P-v criticality and the heat engine efficiency in the Bardeen EinsteinGauss-Bonnet (EGB) AdS black hole space-time.From the P-v plane in the extended phase space,we find that the Bardeen EGB-AdS black hole conforms to Van der Waals (VdW) liquid-gas systems in the extended phase space,and P_cv_/T_c=0.369 of the Bardeen EGB-AdS black hole system is between 0.3333 of the Gauss-Bonnet AdS black hole system and 0.375 of the VdW gas system in the 5-dimensions.Then we construct a heat engine by taking the Bardeen EGB-AdS black hole as the working substance,and consider a rectangle heat cycle in the P-v plane.We find that two cases with different Bardeen parameter e and Gauss-Bonnet parameter a both have the same situation,i.e.as the entropy difference between small black hole and large black hole S2 increases,the heat engine efficiency will increase.Furthermore,as the Bardeen parameter e increases,the efficiency will decrease.However,for the Gauss-Bonnet parameter a,the result is contrary.By comparing with the well-know Carnot heat engine efficiency,we have found the efficiency ratioη/η_c versus entropy S_2 is bounded below l,so it is coincided with the thermodynamical second law.  相似文献   
973.
We study the quantum dynamics of an impurity-doped Bose–Einstein condensate (BEC) system. We show how to generate the macroscopic quantum superposition states (MQSSs) of the BEC by the use of projective measurements on impurity atoms. It is found that the nonclassicality of MQSSs can be manipulated by changing the number of the impurities and their interaction with the BEC. It is shown that the BEC matter-wave field exhibits a collapse and revival phenomenon which reveals the quantum nature of the BEC matter-wave field. We investigate the micro-macro entanglement between the impurities and the BEC, and find enhancement of the micro-macro entanglement induced by the initial quantum coherence of the impurity atoms.  相似文献   
974.
A complete classification of static space times with maximal symmetric transverse spaces is provided, according to their Ricci collineations. The classification is made when one component of Ricci collineation vector field V is non-zero (cases 1~4), two components of V are non-zero (cases 5~10), and three components of V are non-zero (cases 11~14), respectivily. Both non-degenerate (det Rab ≠0) as well as the degenerate (det Rab=0) cases are discussed and some new metrics are found.  相似文献   
975.
976.
考虑零售商采用逆向拍卖方式到个小本经营的制造商处购货,研究供应链中如何设计合同使得零售商单位时间的支出费用最低,采用最优控制的方法和委托代理理论中的显示原理,得出零售商的最优购货机制,同时给出两个简单的购货机制——打分拍卖机制和固定生产时间下的价格拍卖。结果表明由制造商承担的制造费用越多,零售商的进货价格越高;在简单机制下,制造商承担制造费用的大小并不影响最优生产率的制定。  相似文献   
977.
赵峥 《大学物理》2011,30(6):28-31
列出了有关爱因斯坦生平的一些有趣问题,包括他的学习、科学研究,以及他对教育的批评等.  相似文献   
978.
979.
980.
A recent article [J. Steinhauer, Nat. Phys. 2016 , 12, 959] has reported the observation of quantum Hawking radiation and its entanglement in an analogue black hole. Here, the published evidence, its consistency with theoretical bounds, and the statistical significance of the results are analyzed. The analysis raises severe doubts on the observation of Hawking radiation.  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