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981.
《Acta Crystallographica. Section C, Structural Chemistry》2017,73(6):470-475
The 2‐methylbiphenyl‐4,4′‐dicarboxylate (mbpdc2−) ligand has versatile coordination modes and can be used to construct multinuclear structures. Despite this, reports of the synthesis of coordination complexes involving this ligand are scarce. The title compound, poly[[triaquadi‐μ3‐hydroxido‐hexakis(μ4‐2‐methylbiphenyl‐4,4′‐dicarboxylato)calcium(II)hexazinc(II)] monohydrate], {[CaZn6(C15H10O4)6(OH)2(H2O)3]·H2O}n , has been prepared by the hydrothermal assembly of Zn(NO3)2·6H2O, CaCl2 and 2‐methylbiphenyl‐4,4′‐dicarboxylic acid. Two ZnII atoms adopt a four‐coordinated distorted tetrahedral geometry by bonding to three O atoms from three different 2‐methylbiphenyl‐4,4′‐dicarboxylate (mbpdc2−) dianionic ligands and one bridging hydroxide O atom. For the remaining ZnII atom, a five‐coordinate environment is completed half the time by one carboxylate O atom, and then the same carboxylate O atom and an aqua O atom are present the other half of the time, giving a six‐coordinate environment. The CaII atom is coordinated by six O atoms to give an octahedral coordination geometry. The supramolecular secondary building unit (SBU) is a hamburger‐like heptanuclear unit (Zn6CaO30) and these units are interconnected through mbpdc2− carboxylate groups to generate a three‐dimensional framework with the pcu topology. The single net leaves voids that are filled by mutual interpenetration of an independent equivalent framework in a twofold interpenetrating architecture. The title compound shows thermal stability up to 673 K. The excitation and luminescence data showed the emission of a bright‐blue fluorescence. 相似文献
982.
《Acta Crystallographica. Section C, Structural Chemistry》2017,73(9):718-723
The sotagliflozin molecule exhibits two fundamentally different molecular conformations in form 1 {systematic name: (2S ,3R ,4R ,5S ,6R )‐2‐[4‐chloro‐3‐(4‐ethoxybenzyl)phenyl]‐6‐(methylsulfanyl)tetrahydro‐2H‐pyran‐3,4,5‐triol, C21H25ClO5S, (I)} and the monohydrate [C21H25ClO5S·H2O, (II)]. Both crystals display hydrogen‐bonded layers formed by intermolecular interactions which involve the three –OH groups of the xyloside fragment of the molecule. The layer architectures of (I) and (II) contain a non‐hydrogen‐bonded molecule–molecule interaction along the short crystallographic axis (a axis) whose total PIXEL energy exceeds that of each hydrogen‐bonded molecule–molecule pair. The hydrogen‐bonded layer of (I) has the topology of the 4‐connected sql net and that formed by the water and sotagliflozin molecules of (II) has the topology of a 3,7‐connected net. 相似文献
983.
984.
多工况下结构拓扑优化设计 总被引:9,自引:0,他引:9
考虑单元删除和增加对结构应力约束的影响,提出了一种新的多工况下结构的双方向渐进优化方法.首先,基于在结构孔洞或边界周围附加人工材料的思路,建立了结构优化模型和应力灵敏度公式.然后,结合结构应力和应力灵敏度,给出了多工况静力载荷下考虑静应力约束的结构优化准则和算法.开展了结构仿真设计,结果表明给出的方法是正确和有效的,并具有较好的工程应用价值. 相似文献
985.
Pan Jin Wang De-yu 《Acta Mechanica Solida Sinica》2006,19(3):231-240
In this paper, adaptive genetic algorithm (AGA) is applied to topology optimization of truss structure with frequency domain excitations. The optimization constraints include fundamental frequency, displacement responses under force excitations and acceleration responses under foundation acceleration excitations. The roulette wheel selection operator, adaptive crossover and mutation operators are used as genetic operators. Some heuristic strategies are put forward to direct the deletion of the extra bars and nodes on truss structures. Three examples demonstrate that the proposed method can yield the optimum structure form and the lightest weight of the given ground structure while satisfying dynamic response constraints. 相似文献
986.
987.
多孔材料/结构尺度关联的一体化拓扑优化技术 总被引:2,自引:2,他引:2
针对多孔材料的尺度效应和微结构构型的可设计性,提出以宏观结构最大刚度为目标,材料表征体胞构型为变量的材料/结构尺度关联一体化设计新方法.采用有限元超单元技术,验证了材料表征体胞尺度、边长比、平移、对称周期分布方式对构型设计结果的影响,实现了材料宏观布局设计、材料表征体胞构型精细设计以及多尺度均匀化设计的统一。基于凸规划对偶优化求解技术与二次型周长控制约束,完成了快速设计与材料分布棋盘格效应的控制。计算结果表明,在给定材料用量的情况下,该方法能有效地实现蜂窝结构的拓扑优化设计,设计结果充分反映了蜂窝夹层结构的尺度效应,为轻质结构设计提供了新的设计方法。 相似文献
988.
离散变量结构拓扑优化设计研究 总被引:8,自引:2,他引:8
研究了离散变量结构拓扑优化设计的若干问题,讨论了离散型优化模型的合理性,提出截面设计变量的离散程度和全局约束影响最优拓扑,是优化中不可忽视的因素,文中还提出了一种解离散变量桁架,刚架结构拓扑优化的启发式算法。 相似文献
989.
SIMULTANEOUS SHAPE AND TOPOLOGY OPTIMIZATION OF TRUSS UNDER LOCAL AND GLOBAL STABILITY CONSTRAINTS 总被引:5,自引:0,他引:5
GuoXu LiuWei LiHongyan 《Acta Mechanica Solida Sinica》2003,16(2):95-101
A new approach for the solution of truss shape and topology optimization problem sunder local and global stability constraints is proposed. By employing the cross sectional areas of each bar and some shape parameters as topology design variables, the difficulty arising from the jumping of buckling length phenomenon can be easily overcome without the necessity of introducing the overlapping bars into the initial ground structure. Therefore computational efforts can be saved for the solution of this kind of problem. By modifying the elements of the stiffness matrix using Sigmoid function, the continuity of the objective and constraint functions with respect to shape design parameters can be restored to some extent. Some numerical examples demonstrate the effectiveness of the proposed method. 相似文献
990.