全文获取类型
收费全文 | 1460篇 |
免费 | 58篇 |
国内免费 | 3篇 |
专业分类
化学 | 891篇 |
晶体学 | 7篇 |
力学 | 56篇 |
数学 | 102篇 |
物理学 | 465篇 |
出版年
2023年 | 15篇 |
2022年 | 19篇 |
2021年 | 27篇 |
2020年 | 24篇 |
2019年 | 42篇 |
2018年 | 22篇 |
2017年 | 32篇 |
2016年 | 60篇 |
2015年 | 42篇 |
2014年 | 45篇 |
2013年 | 95篇 |
2012年 | 91篇 |
2011年 | 113篇 |
2010年 | 64篇 |
2009年 | 51篇 |
2008年 | 67篇 |
2007年 | 68篇 |
2006年 | 66篇 |
2005年 | 54篇 |
2004年 | 41篇 |
2003年 | 39篇 |
2002年 | 33篇 |
2001年 | 29篇 |
2000年 | 13篇 |
1999年 | 21篇 |
1998年 | 11篇 |
1997年 | 8篇 |
1996年 | 14篇 |
1995年 | 14篇 |
1994年 | 15篇 |
1993年 | 20篇 |
1992年 | 14篇 |
1991年 | 16篇 |
1990年 | 12篇 |
1989年 | 9篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 18篇 |
1983年 | 15篇 |
1982年 | 13篇 |
1981年 | 13篇 |
1980年 | 14篇 |
1979年 | 13篇 |
1978年 | 12篇 |
1977年 | 15篇 |
1976年 | 10篇 |
1975年 | 11篇 |
1973年 | 6篇 |
1971年 | 5篇 |
1966年 | 5篇 |
排序方式: 共有1521条查询结果,搜索用时 31 毫秒
121.
S. K. Das R. K. Chatterjee S. K. Saha 《Journal of Radioanalytical and Nuclear Chemistry》2002,251(1):145-147
Hafnium ion forms a strong complex with nitrilotriacetic acid (NTA). But there is a controversy about the nature of the complex on whether it is a 1:1 or a 1:2 complex. We have carried out an electrophoresis experiment and supplemented data to establish the nature of the complex. Our data indicates that it is a 1:2 complex i.e. [Hf(NTA)2]2- in which the coordination number 8 has been satisfied for hafnium. 相似文献
122.
The diastereoselective synthesis of the macrolactone core of amphidinolide W was successfully accomplished using Evans’ asymmetric alkylation, Aldol reaction, Julia-Kocienski olefination, and Kita’s macrocyclization protocol. 相似文献
123.
Anjan Biswas Abhijit Bandyopadhyay Nikhil K. Singha Anil K. Bhowmick 《Journal of polymer science. Part A, Polymer chemistry》2008,46(24):8023-8040
Direct sulfonation and styrene‐mediated sulfonation were carried out onto metallocene‐based poly(ethylene‐co‐octene) (POE) and poly(ethylene‐co‐butene) (PBE) elastomers to impart polarity on the completely nonpolar rubbery matrices and to prepare a new class of elastomer. The influence of styrene‐grafting and pendant chain length on the degree of sulfonation was also studied. The effects of sulfonation, styrene grafting and styrene‐mediated sulfonation at their optimized levels on various physicomechanical properties were thoroughly investigated, and the resultant properties were correlated with structures of the modified elastomers. Higher extent of sulfonic acid groups were introduced through direct sulfonation in comparison with the styrene‐mediated sulfonation, whereas better thermal and mechanical properties were obtained through styrene‐mediated sulfonation in comparison with the direct sulfonation process. PBE had shown higher degree of sulfonation and percentage grafting than POE. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 8023–8040, 2008 相似文献
124.
A. Chatterjee A. Sarkar Sourav Bhattacharya P. Mukherjee N. Gayathri P. Barat 《Physics letters. A》2008,372(22):4016-4020
Tensile tests were carried out by deforming polycrystalline samples of substitutional Al–2.5%Mg alloy at room temperature for a range of strain rates. The Portevin–Le Chatelier (PLC) effect was observed throughout the strain rate regime. The deformation bands in this region are found to be of type A in nature. From the analysis of the experimental stress time series data we could infer that the dynamics of type A dislocation band propagation is a Markov process. 相似文献
125.
A crystal field (CF) investigation of the magnetic properties and heat capacities of RCuAs2 (R=Pr, Nd, Sm, Tb, Dy, Ho, Er and Yb) has been carried out using the observed average magnetic susceptibilities (1.8-300 K) of the title compounds. The CF parameters proposed for the systems show a systematic variation throughout the rare-earth series. Other physical properties dependent on the CF are also computed and compared with available experimental data. The experimental heat capacity data reported for a limited range of temperature agree well with computed heat capacity for all the compounds (except SmCuAs2 and YbCuAs2). CF J mixing was found to be appreciable for all the samples except YbCuAs2. 相似文献
126.
Pradipta Sinha Moloy Banerjee Abhijit Kundu Sujit Roy 《Journal of Chemical Sciences》2002,114(4):277-283
The reaction of allyl halide and a carbonyl compound under the aegis of tetragonal tin(II) oxide and catalyticd
8,d10 metal complexes provides the corresponding homoallylic alcohol, via a novel allyl tin intermediate. 相似文献
127.
128.
Kashinath Chatterjee 《Annals of the Institute of Statistical Mathematics》1990,42(4):783-803
This paper describes the construction of search designs which permit the estimation of the general mean and main-effects,
and allow the search for and estimation of one possibly unknown non-zero effect among the two-and three-factor interactions
in the general symmetric and asymmetric factorial set-up. 相似文献
129.
Abhijit Biswas Chan-Ho Yang Ramamoorthy Ramesh Yoon H. Jeong 《Progress in Surface Science》2017,92(2):117-141
Scientific interest in atomically controlled layer-by-layer fabrication of transition metal oxide thin films and heterostructures has increased intensely in recent decades for basic physics reasons as well as for technological applications. This trend has to do, in part, with the coming post-Moore era, and functional oxide electronics could be regarded as a viable alternative for the current semiconductor electronics. Furthermore, the interface of transition metal oxides is exposing many new emergent phenomena and is increasingly becoming a playground for testing new ideas in condensed matter physics. To achieve high quality epitaxial thin films and heterostructures of transition metal oxides with atomically controlled interfaces, one critical requirement is the use of atomically flat single terminated oxide substrates since the atomic arrangements and the reaction chemistry of the topmost surface layer of substrates determine the growth and consequent properties of the overlying films. Achieving the atomically flat and chemically single terminated surface state of commercially available substrates, however, requires judicious efforts because the surface of as-received substrates is of chemically mixed nature and also often polar. In this review, we summarize the surface treatment procedures to accomplish atomically flat surfaces with single terminating layer for various metal oxide substrates. We particularly focus on the substrates with lattice constant ranging from 4.00 Å to 3.70 Å, as the lattice constant of most perovskite materials falls into this range. For materials outside the range, one can utilize the substrates to induce compressive or tensile strain on the films and explore new states not available in bulk. The substrates covered in this review, which have been chosen with commercial availability and, most importantly, experimental practicality as a criterion, are KTaO3, REScO3 (RE = Rare-earth elements), SrTiO3, La0.18Sr0.82Al0.59Ta0.41O3 (LSAT), NdGaO3, LaAlO3, SrLaAlO4, and YAlO3. Analyzing all the established procedures, we conclude that atomically flat surfaces with selective A- or B-site single termination would be obtained for most commercially available oxide substrates. We further note that this topmost surface layer selectivity would provide an additional degree of freedom in searching for unforeseen emergent phenomena and functional applications in epitaxial oxide thin films and heterostructures with atomically controlled interfaces. 相似文献
130.
Subhendu Naskar Priyankar Paira Rupankar Paira Shyamal Mondal Arindam Maity Abhijit Hazra Krishnendu B. Sahu Pritam Saha Sukdeb Banerjee Peter Luger Manuela Webe Nirup B. Mondal 《Tetrahedron》2010,66(27-28):5196-5203
An environmentally benign protocol has been described for the synthesis of novel 2-(1′,3′-dihydro-1H-[2,3′]biindolyl-2′-ylidene)-indan-1,3-diones/bis-indolylindane-1,3-diones from ninhydrin and 3-substituted/unsubstituted indoles. It uses montmorillonite K-10 as catalyst in a solvent-free condition under microwave irradiation. The method was also used for the synthesis of novel bisindolylindeno[1,2-b]quinoxaline derivatives. 相似文献