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161.
Zhong‐Min Cen Fa‐Si Li Qing‐Ling Ni Xiu‐Jian Wang Bin Li 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(1):m17-m20
In the title compound, poly[hexaaquabis[μ4‐3,5‐bis(carboxylatomethoxy)benzoato]trizinc(II)], [Zn3(C11H7O8)2(H2O)6]n, there are two crystallographically distinct ZnII cations which are bridged by polycarboxylate ligands in a μ4‐bridging mode. A pair of ligands bridges adjacent Zn atoms to give centrosymmetric dimetal building blocks which act as four‐connected nodes to be further interlinked into a two‐dimensional double‐layered framework with (4,4) topology. Other Zn atoms, lying on inversion centres, occupy the cavities of this topological structure. This submission shows a versatile polycarboxylate ligand with rigid and flexible functional groups, the co‐operation and complementarity of which would meet the coordination requirements of a variety of topological structures. 相似文献
162.
Jun-Bo Chen Dr. Cen Zhou Ru-Qiang Lu Dr. Xin-Chang Wang Hang Qu Dr. Mithu Saha Hao-Liang Liu Prof. Hui Zhang Prof. Xiao-Yu Cao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(5):1293-1299
Triindolo-truxene, a C3-symmetric molecule with a large π-conjugated plane, has six methylene carbon atoms and three aromatic carbon atoms that can be facilely functionalized. Herein, butyl, carbonyl, cyano, and/or malononitrile groups were introduced at six methylene carbon atoms (6-, 14-, 22- or 8-, 16-, 24-positions) and/or three aromatic carbon atoms (2-, 10-, and 18-positions) of triindolo-truxene to produce eight derivatives. Their photophysical properties, electrochemical properties, and molecular assembly can be effectively modulated by substituents and substitution patterns. Incorporation of electron-deficient groups led to redshifts in both the absorption and emission of these derivatives and also lowered their HOMO and LUMO levels. Different substitution patterns resulted in the different intramolecular donor–acceptor interactions. Electron-deficient substituents at the methylene carbon atoms in the 6-, 14-, and 22-positions led to intramolecular charge transfer from the fluorene arms to the truxene core, whereas the corresponding substitutions at the methylene carbon atoms in the 8-, 16-, and 24-positions resulted in intramolecular charge transfer from the truxene core to the fluorene arms. The molecular packing in single crystals and molecular aggregation in solution are also influenced by the substituents and substitution patterns. This work provides a straightforward strategy to alter the properties of triindolo-truxene. 相似文献
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164.
Peipei Cen Dr. Xiangyu Liu Dr. Jesús Ferrando-Soria Yi-Quan Zhang Prof. Gang Xie Prof. Sanping Chen Dr. Emilio Pardo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(15):3884-3892
A family of four mononuclear DyIII β-diketonate complexes with formulas [Dy(tmhd)3(Br2-bpy) ( 1) , [Dy(tmhd)3(Br-bpy)] ( 2 ), [Dy(tmhd)3(dppz)] ( 3 ), and [Dy(tmhd)3(mcdpq)] ( 4 ) (tmhd=2,2,6,6-tetramethyl-3,5-heptanedione, Br2-bpy=5,5′-dibromo-2,2′-bipyridine, Br-bpy=5-bromo-2,2′-bipyridine, dppz=dipyrido [3,2-a:2′,3′-c]phenazine, mcdpq=2-methoxyl-3-cyanodipyrido[3,2-f:2,3′-h]quinoxaline) were prepared by modifying the capping N-donor coligands. DyIII centers in these complexes feature an N2O6 octacoordinate environment with distorted square-antiprismatic D4d symmetry. Magnetic investigations evidenced single-ion magnet behavior in all complexes with energy barriers Ueff of 42.10 ( 1 ), 61.47, ( 2 ), 77.53 ( 3 ), and 2.51 K ( 4 ) in the absence of static field, as well as 206.03 ( 1 ), 224.13 ( 2 ), 247.76 ( 3 ), and 49.70 K ( 4 ) under applied dc field (Hdc=1500 Oe for 1 and 2 ; Hdc=1200 Oe for 3 and 4 ). The different natures of the N-donor ligands induce changes in both the coordination geometry and their intermolecular interactions, which severely impact their magnetic dynamics. The disparities in their magnetic behaviors and the uniaxial anisotropies are also explained and substantiated by theoretical calculations. 相似文献
165.
适用于极低温环境的石墨烯超级电容具有广阔的应用前景。然而,由于片层间严重的堆叠团聚,目前石墨烯超级电容的低温储能性能并不理想。本文使用H2O2氧化刻蚀法制备了孔洞石墨烯(rHGO),将传统有机溶剂碳酸丙烯酯(PC)和低凝固点溶剂甲酸甲酯(MF)混合制备了混合溶剂有机电解液,组装获得了能够在-60 ℃极低温环境下稳定工作的超级电容。结果表明,该超级电容在-60 ℃下的比电容为106.2 F·g-1,相对于常温电容(150.5 F·g-1)的性能保持率高达70.6%,显著优于未做处理的石墨烯(52.3%)以及文献中的其他石墨烯材料。得益于孔洞化形貌中丰富的介孔和大孔所形成的离子传输通道和缩短的离子传输路径,孔洞石墨烯内的离子扩散阻抗远小于普通石墨烯,且受温度降低的影响更小。在-60 ℃的极低温条件下,该超级电容表现出26.9 Wh·kg-1的最大能量密度和18.7 kW·kg-1的最大功率密度,优于传统碳材料的低温超级电容性能。-60 ℃时在5 A·g-1电流密度下循环充放电10000次后电容保持率达89.1%,具有良好的低温循环稳定性。 相似文献
166.
167.
本文研究结构化环境中非马尔科夫耗散系统在长时演化下可能出现的极限环振荡现象. 对于欧姆型谱密度环境中的二能级系统, 由于体系只允许一个束缚态模, 给定初态系统在Bloch空间的长时演化将收敛于一个极限环. 研究揭示了极限环半径与环心位置同环境谱密度函数间的关系. 对于多带光子晶体环境中的二能级系统, 由于其可以存在多个束缚态, 研究展现了系统在长时演化下可能出现的收敛于环面或周期或准周期的振荡行为. 有关环面的特征量与环境谱密度间的量化关系同样得以刻画. 论文随后讨论了两比特系统关联量在局域非马尔科夫耗散环境中长时演化可能出现的特征行为. 相似文献
168.
169.
Highly substituted indenes have been prepared in good yields by the palladium-catalyzed carboannulation of diethyl 2-(2-(1-alkynyl)phenyl)malonate with aryl, benzylic, and alkenyl halides. The reaction conditions and the scope of the process were examined, and a possible mechanism is proposed. 相似文献
170.
In this paper, we have found upper and lower bounds for the spectral norms of r-circulant matrices in the forms A = Cr(F0, F1, …, Fn−1), B = Cr(L0, L1, …, Ln−1), and we have obtained some bounds for the spectral norms of Kronecker and Hadamard products of A and B matrices. 相似文献