全文获取类型
收费全文 | 381篇 |
免费 | 20篇 |
专业分类
化学 | 249篇 |
晶体学 | 3篇 |
力学 | 9篇 |
数学 | 87篇 |
物理学 | 53篇 |
出版年
2023年 | 1篇 |
2022年 | 11篇 |
2021年 | 9篇 |
2020年 | 12篇 |
2019年 | 7篇 |
2018年 | 13篇 |
2017年 | 13篇 |
2016年 | 22篇 |
2015年 | 18篇 |
2014年 | 16篇 |
2013年 | 29篇 |
2012年 | 21篇 |
2011年 | 20篇 |
2010年 | 10篇 |
2009年 | 18篇 |
2008年 | 33篇 |
2007年 | 16篇 |
2006年 | 19篇 |
2005年 | 13篇 |
2004年 | 14篇 |
2003年 | 24篇 |
2002年 | 14篇 |
2001年 | 9篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1975年 | 3篇 |
排序方式: 共有401条查询结果,搜索用时 15 毫秒
161.
Yurii A. Simonov Alexandr A. Dvorkin Marina S. Fonari Tadeush I. Malinowski Elżbieta Luboch Andrzej Cygan Jan F. Biernat Edward V. Ganin Yurii A. Popkov 《Journal of inclusion phenomena and macrocyclic chemistry》1993,15(1):79-89
The crystal structures of two 12-membered crown ethers, benzo-12-crown-4 (1) and naphtho-12-crown-4 (2), have been determined by X-ray analysis. Both structures are molecular. Compound1 is monoclonic,P21/b,a=8.466(3),b=8.019(3),c=33.590(10) Å, =90.99(3)o. The unit cell contains two crystallographically independent molecules of1 with similar conformations. Compound2 is also monoclinic,P21/a,a=24.148(8),b=14.535(4),c=7.987(5) Å, =102.87(2)o. Two independent molecules in the unit cell have significantly different conformations.
Supplementary data relating to this publication have been deposited with the British Library as Supplementary Publication No. SUP 82145 (19 pages). 相似文献
162.
The minimum energy path for the rearrangement LiOB OBLi was calculated with the SCF approximation using a double-zeta plus polarization basis set. Stationary points on the potential surface were studied with the help of the CASSCF method using different choices of active space. The results indicate that LiBO may be regarded as a polytopic type molecule. The relative energies of different geometrical configurations changed considerably when the CASSCF method was used, compared to those obtained at the SCF level, demonstrating the importance of correlation effects for this system. 相似文献
163.
Pisareva IV Konoplev VE Petrovskii PV Vorontsov EV Dolgushin FM Yanovsky AI Chizhevsky IT 《Inorganic chemistry》2004,43(20):6228-6237
The monocarbon carborane [Cs][nido-7-CB(10)H(13)] reacts with the 16-electron [RuCl(2)(PPh(3))(3)] in a solution of benzene/methanol in the presence of N,N,N',N'-tetramethylnaphthalene-1,8-diamine as the base to give a series of 12-vertex monocarbon arene-biruthenacarborane complexes of two types: [closo-2-[7,11-exo-RuClPPh(3)(mu,eta(6)-C(6)H(5)PPh(2))]-7,11-(mu-H)(2)-2,1-RuCB(10)H(8)R] (5, R = H; 6, R = 6-MeO; 7, R = 3-MeO) and [closo-2-(eta(6)-C(6)H(6))-10,11,12-[exo-RuCl(PPh(3))(2)]-10,11,12-(mu-H)(3)-2,1-RuCB(10)H(7)R(1)] (8a, R(1) = 6-MeO; 8b, R(1) = 3-MeO, inseparable mixture of isomers) along with trace amounts of 10-vertex mononuclear hypercloso/isocloso-type complexes [2,2-(PPh(3))(2)-2-H-3,9-(MeO)(2)-2,1-RuCB(8)H(7)] (9) and [2,5-(Ph(3)P)-2-Cl-2-H-3,9-(MeO)(2)-2,1-RuCB(8)H(6)] (10). Binuclear ruthenacarborane clusters of both series were characterized by a combination of analytical and multinuclear NMR spectroscopic data and by single-crystal X-ray diffraction studies of three selected complexes, 6-8. In solution, isomers 8a,b have been shown to undergo the isomerization process through the scrambling of the exo-[RuCl(PPh(3))(2)] fragment about two adjacent triangular cage boron faces B(7)B(11)B(12) and B(8)B(9)B(12). 相似文献
164.
Maria L. Kondratieva Natalia P. Belskaia Alexandr V. Koksharov Koen Robeyns Wim Dehaen Vasiliy A. Bakulev 《Tetrahedron》2007,63(14):3042-3048
The systematic study of oxidative cyclization of 3-hydrazono-1,3-dihydroindole-2-thiones has been carried out and a series of new 2H-[1,2,3]thiadiazolo[5,4-b]indoles has been prepared. The elaborated reaction represents an efficient method for the synthesis of fused 1,2,3-thiadiazoles. 相似文献
165.
Marchenko A Katsonis N Fichou D Aubert C Malacria M 《Journal of the American Chemical Society》2002,124(34):9998-9999
We report on the formation of self-assembled monolayers of 13-(trimethylsilyl)-1-tridecene-6,12-diyne [C13H17-Si(CH3)3], an organosilane derivative with a linear polyunsaturated chain, on Au(111) substrates. Molecular resolution STM images recorded at the liquid-solid interface between gold and tetradecane reveal a long-range and densely packed hexagonal lattice with a ( radical3 x radical3)R30 degrees -like structure commensurate against gold adlattice. 相似文献
166.
The purpose of this paper is to investigate central elements in distribution algebras D i s t(G) of general linear supergroups G = G L(m|n). As an application, we compute explicitly the center of D i s t(G L(1|1)) and its image under Harish-Chandra homomorphism. 相似文献
167.
Dikusar Alexandr Cuharuc Anatolii Tsyntsaru Natalia 《Journal of Solid State Electrochemistry》2023,27(7):1661-1673
Journal of Solid State Electrochemistry - The scientific school of Alexander Frumkin, a world-renowned electrochemist born in Chisinau, was at the origin of the electrochemical science in the... 相似文献
168.
169.
For a fixed multigraph H with vertices w1,…,wm, a graph G is H-linked if for every choice of vertices v1,…,vm in G, there exists a subdivision of H in G such that vi is the branch vertex representing wi (for all i). This generalizes the notions of k-linked, k-connected, and k-ordered graphs.Given a connected multigraph H with k edges and minimum degree at least two and n7.5k, we determine the least integer d such that every n-vertex simple graph with minimum degree at least d is H-linked. This value D(H,n) appears to equal the least integer d′ such that every n-vertex graph with minimum degree at least d′ is b(H)-connected, where b(H) is the maximum number of edges in a bipartite subgraph of H. 相似文献
170.
Dubrovin EV Voloshin AG Kraevsky SV Ignatyuk TE Abramchuk SS Yaminsky IV Ignatov SG 《Langmuir : the ACS journal of surfaces and colloids》2008,24(22):13068-13074
Atomic force microscopy (AFM) was used to study the process of infection of bacterial cells by bacteriophages, for which purpose experimental protocols were elaborated. Three types of bacteriophages were characterized with AFM and transmission electron microscopy (TEM). Bacteriophage interaction with cells was studied for three bacterial hosts: Gram-negative Escherichia coli 057 and Salmonella enteritidis 89 and Gram-positive Bacillus thuringiensis 393. Depending on the phase of lytic cycle, different cell surface changes are observed in AFM images of infected cells in comparison with intact cells: from phage adsorption on the cells and flagella to complete lysis of the cells, accompanied by the release of a large number of newly formed phages. Control experiments (cells without phages and cells with nonspecific phages) did not reveal any surface changes. Penetration of phages inside obligate aerobe Bacillus thuringiensis was shown to be oxygen-dependent and required aeration in laboratory conditions. Our results show great potential of using AFM for numerous fundamental and applied tasks connected with pathogen-host interaction. 相似文献