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   1782篇
  免费   71篇
  国内免费   7篇
化学   1434篇
晶体学   9篇
力学   39篇
数学   173篇
物理学   205篇
  2023年   11篇
  2022年   74篇
  2021年   100篇
  2020年   34篇
  2019年   29篇
  2018年   29篇
  2017年   50篇
  2016年   79篇
  2015年   65篇
  2014年   87篇
  2013年   121篇
  2012年   136篇
  2011年   129篇
  2010年   79篇
  2009年   70篇
  2008年   75篇
  2007年   82篇
  2006年   61篇
  2005年   63篇
  2004年   47篇
  2003年   37篇
  2002年   24篇
  2001年   17篇
  2000年   12篇
  1999年   8篇
  1998年   12篇
  1997年   9篇
  1996年   10篇
  1995年   9篇
  1988年   9篇
  1985年   10篇
  1938年   10篇
  1937年   10篇
  1934年   10篇
  1932年   9篇
  1931年   7篇
  1930年   6篇
  1929年   9篇
  1928年   8篇
  1927年   9篇
  1926年   11篇
  1923年   7篇
  1922年   6篇
  1919年   6篇
  1916年   8篇
  1913年   7篇
  1912年   7篇
  1911年   6篇
  1909年   8篇
  1908年   9篇
排序方式: 共有1860条查询结果,搜索用时 93 毫秒
61.
The aim of this research was to analyse composition, fatty acids distribution and oxidative stability of fats extracted from four samples of baby formulas. The fats were oxidized in a differential scanning calorimeter (DSC) under polythermal (dynamic) conditions and at normal pressure. The DSC experiments were carried out in an oxygen flow atmosphere using different, linearly programmed, heating rates in the range of 4?C12.5?°C/min. The extrapolated onset temperatures were determined using DSC exotherms and used for the assessment of the thermal oxidative stabilities of the samples. Activation energies (E a), pre-exponential factors (Z) and reaction rate constants (k) for oil oxidation under DSC conditions were calculated using the Ozawa?CFlynn?CWall method and the Arrhenius equation. The melting characteristics of the studied fats were obtained. The fats extracted from the agglomerated samples with higher onset temperatures were more stable than the fats extracted from the initial samples of baby formulas.  相似文献   
62.
JPC – Journal of Planar Chromatography – Modern TLC - Three step bivariant multiple development thin-layer chromatography (BMD-TLC) technique was used in the quantitative analysis of...  相似文献   
63.
We report two experiments on graphene nanostructures. The first was performed on a graphene nanoribbon, where the nature of electronic transport was investigated in detail. Electrons or holes are found to localize in pockets of the potential along the ribbon. Transport is governed by the joint action of localization and Coulomb interaction. The temperature-dependence of the conductance shows activated behavior at temperatures above a few Kelvin. The activation energy retraces the edges of Coulomb blockade diamonds found in nonlinear transport. In the second experiment the metallic tip of a low-temperature scanning force microscope was scanned above a graphene quantum dot. In addition to the familiar Coulomb blockade fringes, localized states are detected forming in the constrictions connecting the dot to source and drain.  相似文献   
64.
Russian Journal of General Chemistry - Frequently, in addition to X-ray and spectroscopic approaches, thermal analysis is the method of choice for comprehensive characterization of precipitated...  相似文献   
65.
66.
67.
68.
An effective strategy to enhance the performance of inorganic semiconductors is moving towards organic-inorganic hybrid materials. Here, we report the design of core–shell hybrid materials based on a TiO2 core functionalized with a polyampholytic (poly(dehydroalanine)-graft-(n-propyl phosphonic acid acrylamide) shell (PDha-g-PAA@TiO2). The PDha-g-PAA shell facilitates the efficient immobilization of the photosensitizer Eosin Y (EY) and enables electronic interactions between EY and the TiO2 core. This resulted in high visible-light-driven H2 generation. The enhanced light-driven catalytic activity is attributed to the unique core–shell design with the graft copolymer acting as bridge and facilitating electron and proton transfer, thereby also preventing the degradation of EY. Further catalytic enhancement of PDha-g-PAA@TiO2 was possible by introducing [Mo3S13]2− cluster anions as hydrogen-evolution cocatalyst. This novel design approach is an example for a multi-component system in which reactivity can in future be independently tuned by selection of the desired molecular or polymeric species.  相似文献   
69.
70.
Cisplatin is a drug frequently used in chemotherapy of various types of tumors due to its strong cytostatic activity against cancer cells. However, this therapy is not free from severe side effects related to the nonselective action of the drug. The solution to this problem could be the application of drug-targeted delivery systems (DTDSs). Gold nanoparticles can be used in such systems as selective drug carriers, ensuring its transportation through the bloodstream to destination tissue. The method of DTDSs analysis providing qualitative and quantitative information about the formation of this conjugation is crucial to establish the kinetics of reaction and stoichiometry of reagents, which ensures the best drug binding rate. Moreover, the status of so far proposed techniques/methods dedicated to elaborating the course of DTDSs formation is preliminary and in majority guarantee only the confirmation of drug‒carrier conjugate formation. In this paper, we demonstrate the procedures of reagents’ preparation and cisplatin‒gold nanoparticles DTDS formation, which have a significant influence on the rate and stoichiometry of the reaction. We also present the novel application of CE-ICP-MS hyphenation for effective separation and online monitoring of all components of the reaction mixture.  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