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   476篇
  免费   15篇
  国内免费   4篇
化学   324篇
晶体学   1篇
力学   12篇
数学   37篇
物理学   121篇
  2022年   4篇
  2021年   8篇
  2020年   8篇
  2019年   6篇
  2018年   7篇
  2017年   4篇
  2016年   11篇
  2015年   12篇
  2014年   8篇
  2013年   23篇
  2012年   18篇
  2011年   32篇
  2010年   21篇
  2009年   21篇
  2008年   35篇
  2007年   21篇
  2006年   25篇
  2005年   14篇
  2004年   16篇
  2003年   15篇
  2002年   11篇
  2001年   10篇
  2000年   5篇
  1999年   5篇
  1997年   5篇
  1996年   6篇
  1995年   9篇
  1994年   10篇
  1993年   12篇
  1992年   14篇
  1991年   9篇
  1990年   4篇
  1989年   7篇
  1988年   7篇
  1987年   7篇
  1986年   3篇
  1985年   4篇
  1984年   5篇
  1983年   2篇
  1982年   6篇
  1981年   3篇
  1980年   2篇
  1979年   4篇
  1977年   5篇
  1976年   4篇
  1975年   10篇
  1974年   2篇
  1973年   5篇
  1971年   3篇
  1968年   3篇
排序方式: 共有495条查询结果,搜索用时 15 毫秒
31.
A novel and time-saving method to prepare a Brønsted acidic ionic liquid, 1-carboxymethyl-3-methylimidazolium hydrogen sulfate ([CMI][HSO4]), in high yield and purity was performed under microwave irradiation. The ionic liquid showed an incomparable catalytic efficiency in the microwave-accelerated esterification of arenecarboxylic acids. Moreover, its ability of being recovered and reused many times without loss of activity has made [CMI][HSO4] more favorable from the viewpoint of green chemistry.  相似文献   
32.
In this Letter, we demonstrate that electron spin can influence near-field mediated light propagation through a dense ensemble of subwavelength bimetallic ferromagnetic/nonmagnetic microparticles. In particular, we show that ferromagnetic particles coated with nonmagnetic metal nanolayers exhibit an enhanced magnetic field controlled attenuation of the electromagnetic field propagated through the sample. The mechanism is related to dynamic, electromagnetically induced electron spin accumulation in the nonmagnet. The discovery of an electron spin phenomenon in the light interaction with metallic particles opens the door to the marriage of spintronic and plasmonic technologies and could pave the way for the development of light-based devices that exploit the electron spin state.  相似文献   
33.
34.
In order to develop a recombinant full-length human anti-botulinum neurotoxin A (BoNT/A) antibody, human peripheral blood mononuclear cells (PBMC) were collected from three healthy volunteers and induced for BoNT/A-specific immune response by in vitro immunization. The genes encoding human Fd fragment, consisting of antibody heavy chain variable region and constant region 1 with the genes encoding antibody light chain, were cloned from the immunized PBMC. Afterwards, one combinatory human antigen-binding fragment (Fab) library was constructed using a lambda phage vector system. The size of the constructed library was approximately 105 Escherichia coli transformants. After screening the library by BoNT/A antigen using a plaque lifting with immunostaining approach, 55 clones were identified as positive. The Fab gene of the most reactive clone exhibiting particularly strong BoNT/A binding signal was further subcloned into a full-length human IgG1 antibody gene template in an adenoviral expression vector, in which the heavy and light chains were linked by a foot-and-mouth-disease virus-derived 2A self-cleavage peptide under a single promoter. After the full-length human IgG1 was expressed in mammalian cells and purified with protein L column, sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the heavy and light chains of the antibody were cleaved completely. The affinity expressed as the dissociation constant (K d) for the recombinant human antibody to bind to BoNT/A was determined by indirect enzyme-linked immunosorbent assay and results confirmed that the recombinant full-length human antibody retained BoNT/A-binding specificity with K d value of 10−7 M.  相似文献   
35.
A zeolite-based microengineered reactor was fabricated and tested for 1-pentene epoxidation over titanium silicalite-1 (TS-1) catalyst, which has been selectively incorporated within the microreactor channel using a new synthesis procedure.  相似文献   
36.
The determinatin of the concentration of major steel forming elements in 2–5 g steel samples by PGAA and reference to synthetic standard or single comparator is presented. The relative standard deviation is approximately 5%. The analysis time is about 60 min per sample.  相似文献   
37.
38.
Interferometry is introduced for the first time to the study of Kerr magneto-optic effects. A polarized interferometer is used in direct measurement of the phase relationship between the two Kerr components from the head-on domains in a magnetic thin film.  相似文献   
39.
A thin-beam holographic reconstruction technique to study the 3-D refractive index field of a phase object is described. The advantages and drawbacks of this method are discussed.  相似文献   
40.
In this paper, a novel criterion named the overlap index (OVI) has been proposed to evaluate the separation quality in two-dimensional hyphenated chromatography. This criterion, which is obtained from the maximum value of the Gram determinant constructed by the key spectra, can reveal the degree of two-dimensional hyphenated chromatographic separation. The key spectra are selected based on the so-called D-optimal criterion. According to its geometrical sense meaning the volume spanned by the constructed vectors, OVI criterion can practically reflect the overlap degree of chromatographic peaks. The OVI criterion is further interpreted by comparing the resolution of two-dimensional data into pure chromatograms and spectra. The successful application of this OVI criterion to both of simulated two-dimensional hyphenated data and the real case in analyzing the six reference phenolic compounds from Ginkgo biloba L-leaves shows its reliability and practicality.  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