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991.
A. N. Chekhlov 《Journal of Structural Chemistry》2005,46(2):376-380
Crystal and molecular structures of 2-hydroxyimino-3-methyl-4-nitro-2,5-dihydrothiophene-1,1-dioxide C5H6N2O5S (I) have been re-determined by single crystal X-ray diffraction analysis. The structure of I (space group P212121, a = 6.124(1) Å, b = 9.205(2) Å, c = 14.884(3) Å, Z = 4) was solved by the direct method and refined anisotropically in the full-matrix approximation to R = 0.064 using all 1756 measured independent reflections (automated diffractometer CAD-4, λCuKα, anomalous scattering taken into account). This study proves that the compound I contains a disordered group H-O-N=C, but not the isomeric nitrone group O←N(H)=C, as it has been concluded by the workers who pioneered single crystal X-ray diffraction study of I and erroneously took the second low-occupied oxygen position of the disordered hydroxyimine group for H at N atom. 相似文献
992.
Elisa Huerta Bas van Genabeek Patrick J. M. Stals E. W. Meijer Anja R. A. Palmans 《Macromolecular rapid communications》2014,35(15):1320-1325
Here, a modular approach is reported to introduce a specific function into single‐chain polymeric nanoparticles (SCPNs). Hereto, an amphiphilic polymer with pendant benzene‐1,3,5‐tricarboxamide (BTA) units is mixed with a “free” BTA that contains a functional group, either a fluorescent naphthalimide or a catalytically active l ‐proline. Taking advantage of hydrophobic interactions and self‐recognition properties of the BTA units, the “free” BTAs are captured into the interior of the SCPN in water as evidenced by fluorescence studies. To illustrate that function can be readily introduced using a modular approach, l ‐proline‐based BTAs are incorporated to procure a catalytically active SCPN in water. The aldol reaction between p‐nitrobenzaldehyde and cyclohexanone shows good conversions at low catalyst loadings and substrate concentrations, and high stereoselectivities are obtained (de = 91% and ee = 98%).
993.
The amplitude
0 of the interfacial free energy per unit area (or surface tension) of the body-centered-cubic Ising model is found using a direct monte carlo simulation technique. The combination
2/kBTc, where is the correlation length, is shown to agree within the precision of the simulations with a previously reported estimate for the simple cubic lattice. Evidence is also presented for the universality of the finite-size scaling amplitude for the surface tension. 相似文献
994.
995.
Results of a detailed crystallographic study of the structural phase transitions in LiKSO4, carried out using single crystal neutron diffraction at ambient and below-ambient temperatures (300–100 K), are presented. The study indicates two clear phase transitions at 205 K (from space group P63 to space group P31c), at 189 K (to space group Cc) and a third transition at about 130 K in the cooling cycle. The corresponding temperatures are 250 K, 200 K and 138 K in the heating cycle. The existence of twins, mixed phases, and extremely sluggish kinetics for the various phase transitions, as well as the structural details of the various phases in this mixed salt, can explain the apparent inconsistencies in the results of several experimental investigations reported in the literature. 相似文献
996.
We consider variational problems involving nonlocal free energy functionals that arise from Gibbs measures with Kac potentials and are related to the characterization of the optimal (i.e., typical) shape of an interface under given constraints on the magnetization profile. 相似文献
997.
Emiko Kazuma Minhui Lee Jaehoon Jung Michael Trenary Yousoo Kim 《Angewandte Chemie (International ed. in English)》2020,59(20):7960-7966
Chemical reactions induced by plasmons achieve effective solar‐to‐chemical energy conversion. However, the mechanism of these reactions, which generate a strong electric field, hot carriers, and heat through the excitation and decay processes, is still controversial. In addition, it is not fully understood which factor governs the mechanism. To obtain mechanistic knowledge, we investigated the plasmon‐induced dissociation of a single‐molecule strongly chemisorbed on a metal surface, two O2 species chemisorbed on Ag(110) with different orientations and electronic structures, using a scanning tunneling microscope (STM) combined with light irradiation at 5 K. A combination of quantitative analysis by the STM and density functional theory calculations revealed that the hot carriers are transferred to the antibonding (π*) orbitals of O2 strongly hybridized with the metal states and that the dominant pathway and reaction yield are determined by the electronic structures formed by the molecule–metal chemical interaction. 相似文献
998.
Anna Giusti Dr. Gaëlle Charron Dr. Sandra Mazerat Jean‐Daniel Compain Pierre Mialane Prof. Anne Dolbecq Dr. Eric Rivière Dr. Wolfgang Wernsdorfer Dr. Rosa Ngo Biboum Bineta Keita Dr. Louis Nadjo Prof. Arianna Filoramo Dr. Jean‐Philippe Bourgoin Dr. Talal Mallah Prof. 《Angewandte Chemie (International ed. in English)》2009,48(27):4949-4952
A POM to remember : Hexanuclear FeIII polyoxometalate (POM) single‐molecule magnets (see structure) can be noncovalently assembled on the surface of single‐wall carbon nanotubes. Complementary characterization techniques (see TEM image and magnetic hysteresis loops) demonstrate the integrity and bistability of the individual molecules, which could be used to construct single‐molecule memory devices.
999.
1000.
气体开关是脉冲功率技术中广泛应用的关键部件之一,高功率、高性能气体开关的技术研究及设计具有重要意义,陡化前沿是开关技术研究的重要内容。分析了气体开关的击穿机理和击穿通道的分布规律。对气体开关充分老练,开关击穿点和击穿通道将相对稳定,实验研究了开关间距和电场对脉冲前沿的影响。击穿电场较低时,减小开关间距有利于陡化脉冲前沿;击穿电场较大时(大于180 kV/cm),开关间隙(电感)对输出脉冲前沿的影响减弱,气体开关的击穿电场成为影响输出脉冲前沿的关键因素。研究结果表明,增大开关的击穿场强,是陡化开关脉冲前沿的有效途径。 相似文献