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   12998篇
  免费   470篇
  国内免费   61篇
化学   9512篇
晶体学   116篇
力学   306篇
综合类   1篇
数学   1452篇
物理学   2142篇
  2023年   94篇
  2022年   199篇
  2021年   339篇
  2020年   284篇
  2019年   278篇
  2018年   234篇
  2017年   180篇
  2016年   426篇
  2015年   366篇
  2014年   460篇
  2013年   715篇
  2012年   903篇
  2011年   1010篇
  2010年   607篇
  2009年   524篇
  2008年   852篇
  2007年   810篇
  2006年   785篇
  2005年   722篇
  2004年   614篇
  2003年   490篇
  2002年   397篇
  2001年   194篇
  2000年   164篇
  1999年   128篇
  1998年   118篇
  1997年   122篇
  1996年   157篇
  1995年   100篇
  1994年   107篇
  1993年   110篇
  1992年   92篇
  1991年   53篇
  1990年   54篇
  1989年   43篇
  1988年   61篇
  1987年   40篇
  1986年   46篇
  1985年   80篇
  1984年   57篇
  1983年   46篇
  1982年   60篇
  1981年   49篇
  1980年   33篇
  1979年   38篇
  1978年   48篇
  1977年   37篇
  1976年   31篇
  1975年   28篇
  1974年   30篇
排序方式: 共有10000条查询结果,搜索用时 703 毫秒
1.
2.
3.
Journal of Thermal Analysis and Calorimetry - The aim of this work is to synthesize and characterize a new structured silver–clay dried, calcined or sintered at different temperatures...  相似文献   
4.
We have synthesized a series of triarylamine‐cored molecules equipped with an adjacent amide moiety and dendritic peripheral tails in a variety of modes. We show by 1H NMR and UV/Vis spectroscopy that their supramolecular self‐assembly can be promoted in solution upon light stimulation and radical initiation. In addition, we have probed their molecular arrangements and mesomorphic properties in the bulk by integrated studies on their film state by using differential scanning calorimetry (DSC), variable‐temperature polarizing optical microscopy (VT‐POM), variable‐temperature X‐ray diffraction (VT‐XRD), and atomic force microscopy (AFM). Differences in the number and the disposition of the peripheral tails significantly affect their mesomorphic properties associated with their lamellar‐ or columnar‐packed nanostructures, which are based on segregated stacks of the triphenylamine cores and the lipophilic/lipophobic periphery. Such structural tuning is of interest for implementation of these soft self‐assemblies as electroactive materials from solution to mesophases.  相似文献   
5.
6.
Editorial 69     
Foundations of Chemistry -  相似文献   
7.
Central European Journal of Operations Research - Societal awareness and legislation changes concerning sustainability have affected how organizations generate value for stakeholders, as well as...  相似文献   
8.
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   
9.
Journal of Solid State Electrochemistry - In this study, galvanostatic electrolysis, through the use of the platinum supported on Ti (Ti/Pt) and Ti/TiO2-nanotubes/PbO2 anodes, was conducted in an...  相似文献   
10.
An innovative volatolomic approach employs the detection of biomarkers present in cerumen (earwax) to identify cattle intoxication by Stryphnodendron rotundifolium Mart., Fabaceae (popularly known as barbatimão). S. rotundifolium is a poisonous plant with the toxic compound undefined and widely distributed throughout the Brazilian territory. Cerumen samples from cattle of two local Brazilian breeds (‘Curraleiro Pé-Duro’ and ‘Pantaneiro’) were collected during an experimental intoxication protocol and analyzed using headspace (HS)/GC–MS followed by multivariate analysis (genetic algorithm for a partial least squares, cluster analysis, and classification and regression trees). A total of 106 volatile organic metabolites were identified in the cerumen samples of bovines. The intoxication by S. rotundifolium influenced the cerumen volatolomic profile of the bovines throughout the intoxication protocol. In this way, it was possible to detect biomarkers for cattle intoxication. Among the biomarkers, 2-octyldecanol and 9-tetradecen-1-ol were able to discriminate all samples between intoxicated and nonintoxicated bovines. The cattle intoxication diagnosis by S. rotundifolium was accomplished by applying the cerumen analysis using HS/GC–MS, in an easy, accurate, and noninvasive way. Thus, the proposed bioanalytical chromatography protocol is a useful tool in veterinary applications to determine this kind of intoxication.  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