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911.
Shantanu Mishra Doreen Beyer Kristjan Eimre Ricardo Ortiz Joaquín Fernndez‐Rossier Reinhard Berger Oliver Grning Carlo A. Pignedoli Roman Fasel Xinliang Feng Pascal Ruffieux 《Angewandte Chemie (International ed. in English)》2020,59(29):12041-12047
Triangular zigzag nanographenes, such as triangulene and its π‐extended homologues, have received widespread attention as organic nanomagnets for molecular spintronics, and may serve as building blocks for high‐spin networks with long‐range magnetic order, which are of immense fundamental and technological relevance. As a first step towards these lines, we present the on‐surface synthesis and a proof‐of‐principle experimental study of magnetism in covalently bonded triangulene dimers. On‐surface reactions of rationally designed precursor molecules on Au(111) lead to the selective formation of triangulene dimers in which the triangulene units are either directly connected through their minority sublattice atoms, or are separated via a 1,4‐phenylene spacer. The chemical structures of the dimers have been characterized by bond‐resolved scanning tunneling microscopy. Scanning tunneling spectroscopy and inelastic electron tunneling spectroscopy measurements reveal collective singlet–triplet spin excitations in the dimers, demonstrating efficient intertriangulene magnetic coupling. 相似文献
912.
Ana Barragn Ane Sarasola Lucia Vitali 《Angewandte Chemie (International ed. in English)》2020,59(36):15599-15602
Efficiency in charge‐transport is a fundamental but demanding prerequisite to allow better exploitation of molecular functionalities in organic electronics and energy‐conversion systems. Here, we report on a mechanism that enables a one‐dimensional conductance structure by connecting discrete molecular states at 2.1 eV through the pores of a metal–organic network on Cu(110). Two adjacent, periodic and isoenergetic contributions, namely a molecular resonance and the confined surface‐state, add‐up leading to anisotropic structures, as channels, observable in real‐space conductance images. The adsorption configurations of Br atoms, inorganic byproduct of the redox‐reacted 4,7‐dibromobenzo[c]‐1,2,5‐thiadiazole (2Br‐BTD) molecules on the copper surface, drive the confinement of the Cu surface state within the pores and critically control the channel continuity. Small displacements of the Br atoms change the local surface potential misaligning the energy levels. This work visualizes the effect of order‐disorder transitions caused by the movement of single atoms in the electronic properties of two‐dimensional organic networks. 相似文献
913.
《Arabian Journal of Chemistry》2020,13(5):5326-5331
The electrochemical behavior of PbO2/PbSO4 electrode is investigated in 4.5 M H2SO4 in presence of three surfactants, Sodium Dodecyl Sulfate (SDS), Cetyltrimethylammonium bromide (CTAB) and Sodium tripolyphosphate (STPP), using cyclic voltametry, electrochemical spectroscopy impedance and galvanostatic discharge as techniques. The micro morphology of the surface of the modified PbO2 electrodes is examined by scanning electron microscopy. The results show that SDS and CTAB when added in the electrolyte could refine the coating particles and change the roughness of the surface of the electrode leading to a thin film of PbO2 with amorphous character. In addition, SDS and CTAB shift the hydrogen evolution potential towards more negative values, improve the discharge capacity of the anodic layer and accelerate the charge transfer. Under cathodic polarization, CTAB presents the lowest value of the charge transfer resistance Rct. In the contrary, STPP shifts the oxygen evolution potential towards more positive values, passivates the surface of the electrode and inhibits completely the reaction of PbO2 formation. 相似文献
914.
Wen-Tong Chen 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(2):133-138
Porphyrins and metalloporphyrins can generally show attractive structural motifs and interesting properties. A new copper porphyrin, namely poly[[μ‐chlorido‐[μ5‐5,10,15,20‐tetrakis(pyridin‐4‐yl)‐21H,23H‐porphine]tricopper(I)] [aquadichloridocopper(II)]], {[Cu3(C40H24N8)Cl][CuCl2(H2O)]}n ( 1 ), was synthesized by the self‐assembly of copper chloride with 5,10,15,20‐tetrakis(pyridin‐4‐yl)‐21H,23H‐porphine under solvothermal conditions. The structure of this copper porphyrin was characterized by single‐crystal X‐ray crystallography and elemental analysis. The porphyrin macrocycle shows a distorted saddle geometry, with the four pyrrole rings slightly distorted in an alternating mode either upwards or downwards. The copper ions show three‐coordinated triangular and four‐coordinated square‐planar geometries. Every copper–porphyrin unit connects to 12 others via four μ4‐bridging Cu2Cl moieties to complete the three‐dimensional framework of compound 1 , with isolated CuCl2(H2O) units located in the voids. This copper porphyrin displays a red photoluminescence. Electrochemical measurements showed that compound 1 has two redox waves (E1/2 = ?160 and 91 mV). 相似文献
915.
磁场对非对称量子点中极化子性质的影响 总被引:4,自引:1,他引:3
采用线性组合算符和幺正变换方法研究磁场对非对称量子点中弱耦合磁极化子性质的影响.导出了非对称量子点中弱耦合磁极化子的振动频率、基态能量和基态结合能随量子点的横向和纵向有效受限长度、磁场和电子-声子耦合强度的变化关系.数值计算结果表明:非对称量子点中弱耦合磁极化子的基态能量和基态结合能随量子点的横向和纵向有效受限长度的增加而迅速增大.随回旋频率的增加而增大,随电子-声子耦合强度的增加而减小. 相似文献
916.
917.
918.
利用循环伏安法制备了聚对氨基苯磺酸修饰电极, 研究了尿酸在该修饰电极上的电化学行为. 结果表明, 该电极对尿酸有较强的电催化作用, 并对抗坏血酸有较强的抗干扰能力. 在pH 5.6的乙酸盐缓冲溶液中, 用循环伏安法和差分脉冲伏安法在该电极上测定了尿酸, 其线性范围分别为1.0×10-5~2.0×10-4 mol/L和4.0×10-7~1.0×10-5 mol/L, 检出限分别为6.0×10-6 mol/L和1.0×10-7 mol/L. 已用于尿液中尿酸的测定. 相似文献
919.
920.