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91.
Michael G. B. Drew Michael J. Hudson Peter B. Iveson Charles Madic 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(4):434-435
The title compound, aquatris(nitrato)[2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine]samarium dihydrate, [Sm(NO3)3(C18H12N6)(H2O)]·2H2O, was prepared from Sm(NO3)3·6H2O and 2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine. The metal atom is ten‐coordinate being bonded to the terdentate TPTZ ligand, three bidentate nitrates and a water molecule. 相似文献
92.
Pance Naumov Mirjana Ristova Michael G. B. Drew Seik Weng Ng 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(9):e372-e373
In the title compound, [Ni(C2H3O)2(C3H4N2)4], the Ni atom is coordinated centrosymmetrically by four N and two O atoms in an octahedral coordination [Ni—N = 1.986 (3) and 2.054 (3) Å; Ni—O = 2.697 (3) Å]. The O atoms of the acetate anions form hydrogen bonds to adjacent imidazole moieties, with the free O atom forming a somewhat shorter bond [N?O = 2.679 (3) and 2.870 (4) Å]. The hydrogen bonds give rise to a two‐dimensional layer structure. 相似文献
93.
Teresa Avilés António Dinis Michael G. B. Drew Vitor Félix 《Monatshefte für Chemie / Chemical Monthly》2000,6(1):1305-1310
The self-assembly of Ag[BF4] with trans-azobenzene in dichloromethane yields a new coordination polymer ([Ag(μ-trans-azobenzene)H2O][BF4])n which was characterized by X-ray single crystal diffraction. The crystal consists of 1-D zigzag cationic chains made up from [Ag(H2O)]+ units linked by trans-azobenzene bridges and BF− 4 anions. Hydrogen bonding interactions between the chains and BF− 4 anions occur via intermolecular C*H⋯F and O*H⋯F contacts, and the crystal displays a 2-D supramolecular structure. 相似文献
94.
Structural Chemistry - In general, entropy is not additive for the system of a single molecule. We show this by demonstrating that the entropy of a monoxide species, before and after subtracting... 相似文献
95.
The strong intermolecular interactions mediated by short hydrophobic sequences (e.g., 17-20, -l-Leu-l-Val-l-Phe-l-Phe-) in the middle of Aβ are known to play a crucial role in the neuropathology of Alzheimer's disease. FTIR, TEM and Congo red binding studies indicated that a series of l-Ala substituted terminally protected peptides related to the sequence 17-20 of the β-amyloid peptide, adopted β-sheet conformations. However, the Aib-modified analogues disrupt the β-sheet structure and switch over to a 310 helix with increasing number of Aib residues. X-ray crystallography shed some light on the change from sheet to helix at atomic resolution. 相似文献
96.
97.
The operational research/management science journals contain an extensive literature that addresses the corporate cash management problem; yet few, if any, companies make use of any of this published work in their daily cash-management decision making. A review of the literature suggests that the reason for this lack of applications may well be poor problem formulation—the problems that are solved in the literature as ‘cash management’ problems evolve from a ‘hard systems’ view of real-world cash management. However, the problem as perceived by cash managers involves both dynamic and loosely structured components which are difficult to model using classical (i.e. ‘hard systems’) approaches.We therefore decided to approach the cash management problem as an experiment in the use of a novel visual interactive problem solving (VIPS) methodology. The aim of the experiment was to develop an implementable, visual interactive model to support daily cash management decision making. Working closely with a corporate cash manager, we first developed a visual model of his daily decision problem and then agreed on the feasible options and the interactive requirements. At this stage, the problem was sufficiently well defined for a mathematical model to be built and the visual model made ‘smart’.This paper discusses the results of this experiment and suggests that VIPS may have distinct advantages as a problem-solving technique in loosely structured, ‘messy’ problem situations. 相似文献
98.
Robert D Gilbertson Drew Gorman-Lewis Hans-Christoph Weiss Michael M Haley 《Tetrahedron》2004,60(5):1215-1223
Several 1,2-diphenyl- and 1,2,3-triphenyl-3-alkynylcyclopropenes have been prepared in moderate to very good yields by the reaction of acetylenic nucleophiles with the appropriate cyclopropenylium salt. Single crystal X-ray structures of four of the cyclopropenes were obtained. Stereoselective reduction of the triple bond failed in all cases, whereas model compounds lacking the cyclopropene moiety were reduced successfully. A rational for this lack of reactivity is proposed. The solution-phase thermochemistry of the 3-alkynyl-1,2,3-triphenylcyclopropenes was explored, affording 3-alkynyl-1H-indenes in moderate to good yields. 相似文献
99.
100.