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   458篇
  免费   16篇
  国内免费   1篇
化学   282篇
晶体学   8篇
力学   21篇
数学   95篇
物理学   69篇
  2023年   4篇
  2022年   15篇
  2021年   13篇
  2020年   14篇
  2019年   19篇
  2018年   17篇
  2017年   10篇
  2016年   17篇
  2015年   20篇
  2014年   24篇
  2013年   39篇
  2012年   29篇
  2011年   30篇
  2010年   22篇
  2009年   18篇
  2008年   30篇
  2007年   25篇
  2006年   17篇
  2005年   19篇
  2004年   16篇
  2003年   6篇
  2002年   16篇
  2001年   3篇
  2000年   3篇
  1999年   5篇
  1998年   3篇
  1997年   1篇
  1996年   3篇
  1995年   1篇
  1994年   4篇
  1993年   2篇
  1992年   1篇
  1991年   1篇
  1985年   4篇
  1983年   2篇
  1982年   2篇
  1981年   1篇
  1980年   1篇
  1979年   4篇
  1978年   1篇
  1976年   1篇
  1975年   3篇
  1974年   1篇
  1973年   4篇
  1970年   1篇
  1966年   1篇
  1957年   1篇
  1955年   1篇
排序方式: 共有475条查询结果,搜索用时 46 毫秒
391.
In this paper, we study the existence and non-existence of the positive solution to a semilinear elliptic equation with the harmonic potential and power type nonlinearity. First, we obtain non-existence result in three space dimension with the Sobolev critical nonlinearity. Next, we prove that there exists a global bifurcation branch with the Sobolev supercritical nonlinearity.  相似文献   
392.
393.
394.
Eight tridentate bipyrazole derivatives with different side arms have been prepared in one step and with good yields. The products were screened for their cytotoxic activity against three tumor cell lines—human breast cancer cell line MDA-MB231, human prostate cancer cell line PC3, and human colorectal cell line LoVo, by use of colorimetric MTT assay. Structure–activity relationships reflected the effect of substituted drugs. Among this series, two compounds had remarkable in-vitro antiproliferative activity against the LoVo cell line with IC50 values ranging from 2.6 to 2.7 μg ml?1. All the compounds had suitable drug-like characteristics according to Lipinski’s rule.  相似文献   
395.
396.
In recent years, metal-rich sulfides of the pentlandite type (M9S8) have attracted considerable attention for energy storage applications. However, common synthetic routes towards pentlandites either involve energy intensive high temperature procedures or solvothermal methods with specialized precursors and non-sustainable organic solvents. Herein, we demonstrate that ball milling is a simple and efficient method to synthesize nanosized bimetallic pentlandite particles (Fe4.5Ni4.5S8, Pn) with an average size of ca. 250 nm in a single synthetic step from elemental- or sulfidic mixtures. We herein highlight the effects of the milling ball quantity, precursor types and milling time on the product quality. Along this line, Raman spectroscopy as well as temperature/pressure monitoring during the milling processes provide valuable insights into mechanistic differences between the mechanochemical Pn-formation. By employing the obtained Pn-nanosized particles as cathodic electrocatalysts for water splitting in a zero-gap PEM electrolyzer we provide a comprehensive path for a potential sustainable future process involving non-noble metal catalysts.

A sustainable and rapid mechanochemical method for the preparation of bimetallic nanosized pentlandite particles as cathode material is developed and tested within zero-gap PEM cells.  相似文献   
397.
398.
399.
400.
Access to lanthanide acetate coordination compounds is challenged by the tendency of lanthanides to coordinate water and the plethora of acetate coordination modes. A straightforward, reproducible synthetic procedure by treating lanthanide chloride hydrates with defined ratios of the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) has been developed. This reaction pathway leads to two isostructural crystalline anhydrous coordination complexes, the polymeric [C2mim]n[{Ln2(OAc)7}n] and the dimeric [C2mim]2[Ln2(OAc)8], based on the ion size and the ratio of IL used. A reaction with an IL : Ln-salt ratio of 5 : 1, where Ln=Nd, Sm, and Gd, led exclusively to the polymer, whilst for the heaviest lanthanides (Dy−Lu) the dimer was observed. Reaction with Eu and Tb resulted in a mixture of both polymeric and dimeric forms. When the amount of IL and/or the size of the cation was increased, the reaction led to only the dimeric compound for all the lanthanide series. Crystallographic analyses of the resulting salts revealed three different types of metal-acetate coordination modes where η2μκ2 is the most represented in both structure types.  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