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   15944篇
  免费   688篇
  国内免费   45篇
化学   10821篇
晶体学   207篇
力学   498篇
综合类   1篇
数学   1236篇
物理学   3914篇
  2023年   184篇
  2022年   300篇
  2021年   424篇
  2020年   492篇
  2019年   564篇
  2018年   520篇
  2017年   493篇
  2016年   709篇
  2015年   497篇
  2014年   800篇
  2013年   1380篇
  2012年   1227篇
  2011年   1263篇
  2010年   835篇
  2009年   641篇
  2008年   830篇
  2007年   816篇
  2006年   645篇
  2005年   602篇
  2004年   441篇
  2003年   360篇
  2002年   239篇
  2001年   175篇
  2000年   143篇
  1999年   107篇
  1998年   78篇
  1997年   106篇
  1996年   97篇
  1995年   88篇
  1994年   82篇
  1993年   101篇
  1992年   104篇
  1991年   80篇
  1990年   70篇
  1989年   81篇
  1988年   61篇
  1987年   50篇
  1986年   52篇
  1985年   81篇
  1984年   77篇
  1983年   63篇
  1982年   59篇
  1981年   54篇
  1980年   55篇
  1979年   70篇
  1978年   62篇
  1977年   56篇
  1976年   49篇
  1975年   44篇
  1973年   26篇
排序方式: 共有10000条查询结果,搜索用时 16 毫秒
1.
Hooda  Anjli  Dalal  Anuj  Nehra  Kapeesha  Singh  Sitender  Kumar  Sumit  Singh  Devender 《Journal of fluorescence》2022,32(4):1413-1424
Journal of Fluorescence - A series of europium diketonate complexes with 1-phenyl-1,3-butanedione (PBD) and 1,10-phenanthroline derivatives were synthesized and explored spectroscopically....  相似文献   
2.
Molecular Diversity - The terminal oxidases of the oxidative phosphorylation pathway play a significant role in the survival and growth of M. tuberculosis, targeting these components lead to...  相似文献   
3.
Theoretical and Mathematical Physics - We discuss the gravitational collapse of a spherically symmetric perfect fluid distribution of uniformly contracting stars. In a uniformly contracting star,...  相似文献   
4.
Journal of Thermal Analysis and Calorimetry - In the case of flow boiling, the prediction of vapour fraction in the horizontal microchannel is a severe issue using the numerical technique....  相似文献   
5.
Russian Journal of General Chemistry - In the current study, some new quinoxaline linked 1,3,4-oxadiazole sulfonamide hybrids have been designed, synthesized and characterized by IR, 1H and 13C...  相似文献   
6.
As the application of electrocatalyst continues to expand, envisaging the hidden mechanisms occurring at various length scale affecting the catalytic efficiency became important. To enhance the stability of electrocatalyst and reduce the cost, it is of paramount importance to reveal the active site's dynamics (using in situ techniques for getting the real-time information) which directly affect the reactions such as oxygen evolution reaction, hydrogen evolution reaction, and so on. Since such reactions are crucial for many engineering and scientific applications, in situ characterization techniques are required, which could capture such reactions happening at a different length and time scale. This article analyzes the recent progress made in the field of electrocatalyst's characterization using in situ neutron techniques. The article also paves the future path and has delineated the future challenges involved in multiscale correlative techniques (e.g., neutron techniques in the combination of synchrotron or microscopic techniques) used for getting the multiscale (atomic to micrometer range) mechanistic information about the electrocatalyst's working and degradation.  相似文献   
7.
We investigate the possibility of phantom crossing in the dark energy sector and the solution for the Hubble tension between early and late universe observations. We use robust combinations of different cosmological observations, namely the Cosmic Microwave Background (CMB), local measurement of Hubble constant (H0), Baryon Acoustic Oscillation (BAO) and SnIa for this purpose. For a combination of CMB+BAO data that is related to early universe physics, phantom crossing in the dark energy sector was confirmed at a 95% confidence level and we obtained the constraint H0=71.03.8+2.9 km/s/Mpc at a 68% confidence level, which is in perfect agreement with the local measurement by Riess et al. We show that constraints from different combinations of data are consistent with each other and all of them are consistent with phantom crossing in the dark energy sector. For the combination of all data considered, we obtained the constraint H0=70.25±0.78 km/s/Mpc at a 68% confidence level and the phantom crossing happening at the scale factor am=0.8510.031+0.048 at a 68% confidence level.  相似文献   
8.
Journal of Thermal Analysis and Calorimetry - Nanofluids have gained recent attention because of their potential applications in diverse engineering fields like enhancing thermal transport,...  相似文献   
9.
Journal of Optimization Theory and Applications - In 1979, Pang proved that within the class of semimonotone matrices, $$R_0$$ -matrices are Q-matrices and conjectured that the converse is also...  相似文献   
10.
Solution combustion synthesis (SCS) is a worldwide used methodology for the preparation of inorganic ceramic and composite materials with controlled properties for a wide number of applications, from catalysis to photocatalysis and electrocatalysis, from heavy metal removal to sensoristics and electronics. The high versatility and efficiency of this technique have led to the introduction of many variants, which allowed important optimization to the prepared materials. Moreover, its ecofriendly nature encouraged further studies about the use of sustainable precursors for the preparation of nanomaterials for energy and environment, according to the concept of circular economy. On the other hand, the large variety of expressions to define SCS and the often-contradictory definitions of the SCS parameters witnessed a scarce consciousness of the potentiality of this methodology. In this review article, the most important findings about SCS and the selection criteria for its main parameters are critically reviewed, in order to give useful guidelines to those scientists who want to use this methodology for preparing materials with improved or new functional properties. This review aims as well (i) to bring more clarity in the SCS terminology (ii) to increase the awareness of the SCS as a convenient tool for the synthesis of materials and (iii) to propose a new perspective in the SCS, with special attention to the use of ecofriendly procedures. Part of the review is also dedicated to precautions and limitations of this powerful methodology.  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