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101.
In this paper, the nonlinear dynamical behavior of two coupled pipes conveying pulsating fluid is studied. The connection between the two pipes is considered as a distributed linear spring. Based on this consideration, the equations of motion of the coupled two-pipe system are obtained. The two coupled nonlinear partial differential equations, discretized using the fourth- order Galerkin method, are solved by a fourth-order Runge-Kutta integration algorithm. Results show that the connection stiffness has a significant effect on the dynamical behavior of the coupled system. It is found that for some parameter values the motion types of the two pipes might be synchronous. 相似文献
102.
合成了一种含有多吡啶基配体2,6-双((双(吡啶-2-基甲基)氨基)甲基)吡啶(BPA-TPA)的双核单功能铂(Ⅱ)配合物[Pt2(BPA-TPA)Cl2]Cl2(Pt2-BPA-TPA),以核磁共振波谱和高分辨质谱进行表征,并通过X射线单晶衍射确定了Pt2-BPA-TPA的结构。琼脂凝胶电泳实验表明 Pt2-BPA-TPA 在 10 μmol·L-1的低浓度下可有效切割 pBR322 DNA。通过 CCK-8(cell counting kit-8)实验检测了Pt2-BPA-TPA 对人肺癌细胞系A549的细胞毒性,结果显示Pt2-BPA-TPA 表现出比顺铂更好的抗癌活性,其主要通过触发DNA损伤和上调下游凋亡相关细胞信号通路蛋白(p21蛋白和cleaved-caspase-3)诱导细胞凋亡。 相似文献
103.
104.
We address theoretically the electronic transport through graphene quantum dots with the emphasis on the transmission phase. Analytical and numerical results are presented regarding the existence – or not – of a π lapse of the transmittance phase (and, consequentially, a Fano zero in the transmittance) at the charge neutrality point. A simple universal criterium is found, the phase lapses being always present if the contact sites belong to the same sub‐lattice. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
105.
106.
Dong‐Cai Zhao Geng‐Jie Xiao Ni Ren Zhan‐Ji Ma Sheng‐Hu Wu 《Surface and interface analysis : SIA》2011,43(11):1392-1396
The composites, such as CFRP and GFRP, have been widely applied in spaceflight, for their low specific gravity, low cost, and additional structural stability. However, the high resistivity of the composites severely inhibits their further applications. Therefore, Cr/Al films with low resistivity and high adhesion were deposited on composites by cathodic arc technique. The films were characterized by pull test, Dektak 8 Stylus Profilometer, SEM, XPS, XRD and Z‐82 standard four probes. Results show that the aluminum film of fcc structure is compact and uniform, with resistivity as low as bulk Al. The adhesion between Cr buffer layer and composite substrate was greatly enhanced because of the formation of the chemical bonds, such as Cr? C, Cr? O and Cr? N, at the Cr/composite interface. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
107.
A new approach for the diastereoselective synthesis of (±)-α-noscapine, a phthalide tetrahydroisoquinoline alkaloid exhibiting several biological activities, is described. The strategy features a blocking group-directed Bischler-Napieralski reaction followed by diastereoselective reduction (α/β>23:1). One of the key intermediates, phthalide-3-carboxylic acid, could be efficiently prepared from simple benzoic acid derivative and glyoxylic acid in one-pot. 相似文献
108.
Zhi‐Xiong Wei You‐Heng Gao Fen Yang Hai‐Xiao Lu Lin Ni Xiao‐Hong Zhou 《Helvetica chimica acta》2011,94(7):1320-1325
Three new ent‐kaurane diterpenoids, rabdonervosins D–F ( 1 – 3 ), were isolated from the leaves and stems of Isodon nervosus. Their structures were elucidated on the basis of spectroscopic methods including 1D‐ and 2D‐NMR analyses. Compounds 1 – 3 were evaluated for their cytotoxicity against HepG2, CNE2, PC‐9/ZD, HeLa, MCF‐7, and HCT116 cell lines. No compounds exhibited potent cytotoxicity. 相似文献
109.
M. E. Castro C. Muñoz‐Caro A. Niño 《International journal of quantum chemistry》2011,111(14):3681-3694
This work presents a structural and vibrational theoretical study of n‐propyl cyanide as a function of the nitrile and methyl torsional modes. A potential energy hypersurface is built at the MP4(SDQ)/aug‐cc‐pVTZ//MP2/aug‐cc‐pVTZ theory level. The equilibrium structure is found in a gauche conformation. Another minimum is found for the trans form. The maximum appears in a cis conformation. For the first time, the interconversion barriers between the different forms are calculated. A two‐dimensional anharmonic vibrational Hamiltonian is built for the nitrile and methyl torsional modes. We find the vibrational energy levels to organize in two stacks associated to the gauche and trans forms. Fundamental frequencies of 113.12 and 220.54 cm?1 are predicted for the nitrile and methyl torsions in the equilibrium, gauche, conformer. In addition, we find symmetry allowed transitions between the gauche and trans energy levels stacks. The lowest transition is predicted to appear at 24.49 cm?1. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 相似文献
110.
Arnab Bagchi Yu‐Hsuan Huang Z. F. Xu P. Raghunath Yuan T. Lee Chi‐Kung Ni M. C. Lin Yuan‐Pern Lee 《化学:亚洲杂志》2011,6(11):2961-2976
The photodissociation of gaseous benzaldehyde (C6H5CHO) at 193, 248, and 266 nm using multimass ion imaging and step‐scan time‐resolved Fourier‐transform infrared emission techniques is investigated. We also characterize the potential energies with the CCSD(T)/6‐311+G(3df,2p) method and predict the branching ratios for various channels of dissociation. Upon photolysis at 248 and 266 nm, two major channels for formation of HCO and CO, with relative branching of 0.37:0.63 and 0.20:0.80, respectively, are observed. The C6H5+HCO channel has two components with large and small recoil velocities; the rapid component with average translational energy of approximately 25 kJ mol?1 dominates. The C6H6+CO channel has a similar distribution of translational energy for these two components. IR emission from internally excited C6H5CHO, ν3 (v=1) of HCO, and levels v≤2, J≤43 of CO are observed; the latter has an average rotational energy of approximately 13 kJ mol?1 and vibrational energy of approximately 6 kJ mol?1. Upon photolysis at 193 nm, similar distributions of energy are observed, except that the C6H5+HCO channel becomes the only major channel with a branching ratio of 0.82±0.10 and an increased proportion of the slow component; IR emission from levels ν1 (v=1) and ν3 (v=1 and 2) of HCO and v≤2, J≤43 of CO are observed; the latter has an average energy similar to that observed in photolysis at 248 nm. The observed product yields at different dissociation energies are compared to statistical‐theory predicted results based on the computed singlet and triplet potential‐energy surfaces. 相似文献