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   324篇
  免费   14篇
  国内免费   1篇
化学   221篇
晶体学   13篇
力学   5篇
数学   35篇
物理学   65篇
  2022年   3篇
  2021年   6篇
  2020年   2篇
  2019年   11篇
  2018年   6篇
  2017年   15篇
  2016年   14篇
  2015年   7篇
  2014年   19篇
  2013年   28篇
  2012年   21篇
  2011年   17篇
  2010年   10篇
  2009年   12篇
  2008年   6篇
  2007年   16篇
  2006年   6篇
  2005年   8篇
  2004年   5篇
  2003年   7篇
  2002年   4篇
  2001年   3篇
  1996年   3篇
  1994年   3篇
  1991年   3篇
  1990年   3篇
  1985年   2篇
  1984年   3篇
  1983年   4篇
  1982年   4篇
  1981年   3篇
  1980年   2篇
  1979年   3篇
  1978年   3篇
  1977年   2篇
  1976年   11篇
  1975年   4篇
  1974年   3篇
  1972年   2篇
  1971年   2篇
  1969年   2篇
  1965年   2篇
  1963年   4篇
  1962年   3篇
  1961年   4篇
  1960年   4篇
  1959年   3篇
  1957年   4篇
  1955年   9篇
  1954年   2篇
排序方式: 共有339条查询结果,搜索用时 15 毫秒
1.
JPC – Journal of Planar Chromatography – Modern TLC - This paper includes the development of a novel, systematic, quality by design (QbD)-based high-performance thin-layer...  相似文献   
2.
Sharma  G.  Anthal  S.  Deshmukh  M. B.  Mohire  P. P.  Bhosale  T. R.  Sudarsanakumar  C.  Kant  R. 《Crystallography Reports》2021,66(7):1233-1237
Crystallography Reports - The structure of 3,3'-[(3-sulfanylphenyl)methylene]bis(4-hydroxy-2H-1-benzopyran-2-one) : 5-methyl-1,3-thiazol-2(3H)-imine was determined by X-ray crystallography. It...  相似文献   
3.

The aim of this paper is to compare radioxenon beta–gamma analysis algorithms using simulated spectra with experimentally measured background, where the ground truth of the signal is known. We believe that this is among the largest efforts to date in terms of the number of synthetic spectra generated and number of algorithms compared using identical spectra. We generate an estimate for the minimum detectable counts for each isotope using each algorithm. The paper also points out a conceptual model to put the various algorithms into a continuum. Our results show that existing algorithms can be improved and some newer algorithms can be better than the ones currently used.

  相似文献   
4.
The complex permittivity spectra of tripropylene glycol and water solutions have been obtained by time domain reflectometry (TDR) technique in the frequency range from 10 MHz to 30 GHz and the temperature range 20°C–05°C. The dielectric relaxation parameters such as static dielectric constant and relaxation time were obtained by using the non-linear least square fit method. The intermolecular hydrogen bonding of tripropylene glycol–water has been discussed using the Kirkwood correlation factor and thermodynamic parameters. The activation energy decreases with increase in water content in the mixture as expected in the Arrhenius behaviour. The dielectric constant for mixtures has been fitted to the Bruggeman mixture formula in the non-linear case.  相似文献   
5.
6.
This overview provides insights into the current state‐of‐the‐art solutions to insertion copolymerization of functional olefinic monomers. The challenges in insertion copolymerization of functional olefinic monomers, with a special emphasis on vinyl halides, are highlighted. The crucial design of the Pd–phosphinesulfonate [Pd(PO)] enables up to 3.6 mol % incorporation of vinyl fluoride (VF) in an ethylene–VF copolymerization reaction. In a significant development, insertion copolymerization of industrially relevant functional olefin, that is, vinyl chloride (VC), was unambiguously ascertained, and a detectable amount of VC (0.4 mol %) was incorporated (at the chain end). In a detailed investigation, the in situ existence of (PO)Pd? H species during the polymerization was revealed, and it was demonstrated that these are indeed responsible for VC incorporation. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1–6  相似文献   
7.
Each process configuration for practicing the Fischer–Tropsch synthesis places demands particular to that configuration on the catalyst to be used. We discuss how a particular catalyst, prepared by the OMX (organic matrix combustion) method, when used in conjunction with the Velocys microchannel reactor system, results in a very stable, high performance Fischer–Tropsch synthesis system. With the ability to remove heat far more effectively than a conventional reactor system, this microchannel reactor requires a catalyst with much higher volumetric reactive site density. Further, with such a high volumetric reaction rate, mass transfer effects will be important in both the observed activity and selectivity of the operating catalyst. Nevertheless, the catalyst prepared using the OMX method exhibits an apparent turnover frequency which is considerably higher than reported for other catalysts in the literature. In addition to high activity, an economically useful catalyst must exhibit a stable, high selectivity for liquid products and be able to recover near-fresh performance using a regeneration approach which can be carried out with the catalyst in-place. An example of such a stable, multiply regenerated catalyst is given. Finally, further development has focused on a catalyst with even higher C5+ selectivity.  相似文献   
8.
The visible‐light response of Au nanoparticles (AuNPs) assembled on rGO through different molecular bridges was investigated by transient photocurrent generation. We prepared rGO with two self‐assembled monolayers (SAMs), one linear and the other with aromatic triazoles through a click cycloaddition reaction. A fivefold photocurrent enhancement was observed for triazole linkers over the aminopropyltrimethoxysilane (APTMS) linker. Cyclic voltammetry (CV) and impedance measurements also suggest fast electron transfer on account of the low resistance offered by the click‐modified rGO surface whereby introduction of triazoles offers the efficient bridge between the donor AuNPs and acceptor rGO.  相似文献   
9.
The title compound 1 has been prepared from (+)-3-carene (2) and found to have the same order of activity as its IR-cis isomer 3 reported by us earlier1 The key intermediate methyl IR-trans-2, 2-dimethyl-3-(2-oxopropyl)cyclopropanecarboxylate (4) has been characterised.  相似文献   
10.
The conjugate addition of organomanganese reagents to α,β‐unsaturated aldehydes and allylic bisacetate in presence of Me3Si‐Cl and tetrakis acetonitrile copper(I) tetrafluroborate is described.  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