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951.
CHEN Wen-Tong GUO Guo-Cong ZENG Xi-Rui LI Xin-Fa FANG Xiao-Niu KUANG Han-Mao LIU Dong-Sheng LIU Li-Min 《结构化学》2007,26(10)
The title compound (4,4'-H2bipy)[CdBr4]·H2O 1 has been synthesized via hydrothermal reaction and characterized by X-ray diffraction. The crystal belongs to monoelinic,space group P21/c with a=8.260(3), b=23.926(7), c=9.774(2) (A), β=106.777(9)°,C10H12Br4CdN2O, Mr=608.26, V=1849.4(9)(A)3, Z=4, Dc=2.185 g/cm3, S=1.005, μ(MoKα)=9.814 mm-1, F(000)=1128, R=0.0646 and wR=0.0989. The crystal structure analysis of 1reveals that the title compound features an isolated structure, based on discrete 4,4'-H2bipy moieties and lattice water molecules which are linked by hydrogen bonds together with tetrahedral cadmium atoms terminally coordinated by four bromine atoms. 相似文献
952.
Double Pore Silica Gel Monolith Applied to Liquid Chromatography 总被引:2,自引:0,他引:2
K. Nakanishi H. Minakuchi N. Soga N. Tanaka 《Journal of Sol-Gel Science and Technology》1997,8(1-3):547-552
Silica gels retaining double pore structure in the size ranges of micrometer and nanometer have been applied to the rod-shaped
monolithic column for liquid chromatography. The macropore structure was designed by controlling the phase separation process
induced by the hydrolysis and polycondensation of alkoxysilane, whereas the mesopore structure was tailored by the solvent
exchange treatments on wet gels. The size exclusion chromatograms on polystyrene standards exhibited almost similar features
for octadecyl-modified rod and conventional packed beads columns. The dependence of plate height on the velocity of mobile
phase determined for amylbenzene was by far weaker in the rod column than in the packed beads column, suggesting that additional
geometrical factors should be considered in describing the separation mechanism in the rod column. 相似文献
953.
《Surface and interface analysis : SIA》2003,35(5):429-431
Polycrystalline gold–nickel thin films are deposited on silicon (111) wafers by evaporation in a vacuum of 2 × 10?6 mbar. Concentration profiles of heat‐treated specimens are obtained by Auger electron depth profiling. The heat treatments are carried out in a vacuum furnace of 4 × 10?6 mbar in the temperature interval 473–773 K. The grain boundary diffusion coefficient is determined, using a modified Wipple model, to be (3 × 10?4 cm2 s?1) exp (?0.94 eV kT?1). It is concluded that interdiffusion in the investigated system is characterized by type B kinetics, and that grain boundary diffusion plays a dominant role in the mass transport process of such films. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
954.
The spatial relaxation of electrons to homogeneous states under the action of space-independent electric fields is investigated
in helium, krypton, and N2 plasmas for various electric field strengths. These investigations are based on a new method recently developed for solving
the one-dimensional inhomogeneous electron Boltzmann equation in weakly ionized, collision-dominated plasmas. Elastic as well
as conservative inelastic collisions of electrons with gas atoms have been included in the kinetic treatment. The spatial
relaxation is caused by an imposed direct disturbance in the velocity distribution of the electrons on a spatial boundary.
A pronounced dependence of the relaxation structure and the resultant relaxation length on the atomic data of the electron
collision processes in different gases has been found. Furthermore the relaxation process sensitively depends on the electric
field strength in the region of medium field values. 相似文献
955.
Theoretical study of the unimolecular decomposition mechanisms of energetic TNAD and TNAZ explosives
Min‐Hsien Liu Cheng Chen Yaw‐Shun Hong 《International journal of quantum chemistry》2005,102(4):398-408
Calculation methods based on hybrid Density Functional Theory (DFT) with the basis sets of the B3LYP/6‐31+G(d)//B3LYP/4‐31G(d) method and the differential overlap (INDO) program were used to derive reasonable decomposition mechanisms of 1,4,5,8‐tetranitro‐1,4,5,8‐tetraazadecalin (TNAD) and 1,3,3‐trinitroazetidine (TNAZ) explosives. All possible decomposition species and transition states, including intermediates and products, were identified and their corresponding enthalpy of formation and Gibbs free energy of formation were obtained using polyparametric modification equations. INDO bond energy calculation results reveal the weakest bonding site for reference and determine where cleavage can occur easily. This work is concerned mainly with eliminating HONO (cis or trans form). The activation energy for trans‐form HONO elimination is lower than that of cis‐form HONO elimination in the initial steps of both TNAD and TNAZ decomposition, being 18.5 kJ/mol and 33.3 kJ/mol, respectively. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 相似文献
956.
Xu W. B. Zhou Z. F. He P. S. Pan W.-P. 《Journal of Thermal Analysis and Calorimetry》2004,78(1):113-124
The Flory's gelation theory, non-equilibrium thermodynamic fluctuation theory and Avrami equation have been used to predict
the gel time t
g and the cure behavior of epoxy resin/organo-montmorillonite/diethylenetriamine intercalated nanocomposites at various temperatures
and organo-montmorillonite loadings. The theoretical prediction is in good agreement with the experimental results obtained
by dynamic torsional vibration method, and the results show that the addition of organo-montmorillonite reduces the gelation
time t
gand increases the rate of curing reaction, the value of k, and half-time of cure after gelation point t1/2 decreases with the increasing of cure temperature, and the value of n is ~2 at the lower temperatures (<60°C) and decreases to ~1.5 as the temperature increases, and the addition of organo-montmorillonite
decreases the apparent activation energy of the cure reaction before gelation point, but has no apparent effect on the apparent
activation energy of the cure reaction after gelation point. There is no special curing process required for the formation
of epoxy resin/organo-montmorillonite/diethylenetriamine intercalated nanocomposite.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
957.
Potential dependences of the angle of contact between perfluorodecaline C10F18 and copper, copper(I) sulfide, and copper telluride Cu4Te3 in 0.1 M CH3COONa are measured. The data are in good agreement with the metal hardness measured in 1 M KOH. The uncharged-surface potentials (USP) for copper, copper(I) sulfide, and copper telluride equal 0.05–0.07, –0.02 to –0.04, and 0.05–0.07 V (NHE) in 0.1 M CH3COONa. Studying the effect of Br– ions shows that USP for copper and Cu2S shift in, respectively, the negative and positive directions with an increase in [Br–]. For copper telluride, USP shifts in the positive direction at low Br– concentrations, and at NaBr concentrations in excess of 0.04 M, in the negative direction. 相似文献
958.
K.L Cheng 《Microchemical Journal》2002,72(3):269-276
Non-faradaic potentiometry has been plagued by a great many fundamental errors and a lack of conceptualization. Of greatest concern is the second Nernst equation hiatus. Potentiometry may be generally classified as faradaic and non-faradaic. The former deals with the redox reactions using the Nernst equation to explain the potential origin. The latter deals with the non-redox reactions using the Boltzmann and modified Boltzmann equations to explain the origin of electrode potential. Redox faradaic potentiometry has been well described in the textbooks. However, non-faradaic potentiometry has been almost completely neglected in the literature. Many well-known electrodes, such as the pH glass electrode, common reference electrodes, and ion selective electrodes (ISE) have been mistakenly interpreted as redox reactions or ion exchange reactions. New theories and experimental results show their mechanisms to be non-faradaic in nature. Furthermore, the reaction mechanisms for ISE have been confused in textbooks with redox reactions and the Nernst equation. The ISE potentials originating from adsorption of ions or charged particles based on surface charge density will be explained using the double and counterion triple layers concept. The new counterion triple layer concept may be applied to the potential development of sensors. The reason for a new concept, theory, or mechanism is to better explain the phenomena. Examples will be given of how our new concept explains the capacitor, counterion triple layer, surface adsorbed layers interactions, and the interface structure. We will also discuss the new sensor development based on the new adsorption concept. For the first time a new type of Ag/AgCl reference electrode for non-faradaic potentiometry will be presented, one without a liquid junction and with a Pt wire instead of a salt bridge. They will help open up a new horizon for electrochemical sensor research and may be used under unusual conditions, such as high temperature and high pressure, stirring, etc. 相似文献
959.
Isobaric vapor–liquid equilibrium data at 95.96 kPa for the three binary systems of 2,2,4-trimethylpentane with methyl tert-butyl ether, di-isopropyl ether and dimethoxymethane are determined. A Swietoslawski type ebulliometer is used for the measurements. The experimental T–x data are used to estimate Wilson parameters and the parameters, in turn, are used to calculate vapor phase compositions and activity coefficients. All the systems studied here do not exhibit azeotropes and behave like non-ideal solutions. 相似文献
960.
The polymer reference interaction site model (PRISM) integral equation theory was used to describe the structure and thermodynamic properties of atactic polystyrene (aPS) melt, in which the monomer of aPS is represented with an eight-site model to characterize its microstructure. The intramolecular structure factors needed in the PRISM calculations were obtained from single chain MD simulations. The calculated results indicate that the results by the integral equation method agrees well with experiments, and can reflect the fine microscopic structure of real aPS melt. This work shows that the PRISM theory is a powerful tool for investigating the structure and properties of complex polymers. 相似文献