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871.
A carbon-coated fiber for solid-phase microextraction (SPME) has been prepared from powdered activated carbon (PAC) and a
fused-silica fiber. Scanning electron microscopy of the coating revealed the carbon particles were uniformly distributed on
the surface of the fiber substrate. Efficient extraction of BTEX (benzene, toluene, ethylbenzene, p-xylene, and o-xylene) and halocarbons (chloroform, trichloroethylene, and carbon tetrachloride), with short extraction and desorption times,
was achieved by use of the coated fiber. The maximum working temperature of the coated fiber was 300 °C and the lifetime was
over 140 desorption operations at 260 °C. Limits of quantification (LOQ) of the SPME method for the eight analytes ranged
from 0.01 to 0.94 μg L−1, and relative standard deviations (RSD) were below 7.2% (n=6). Recoveries were 87.9–113.4% when the method was applied to the analysis of BTEX and the halocarbons in real aqueous samples.
An erratum to this article is available at . 相似文献
872.
Waller MP Howard ST Platts JA Piltz RO Willock DJ Hibbs DE 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(29):7603-7614
The charge distribution of taurine (2-aminoethane-sulfonic acid) is revisited by using an orbital-based method that describes the density in a fixed molecular orbital basis with variable orbital occupation numbers. A new neutron data set is also employed to explore whether this improves the deconvolution of thermal motion and charge density. A range of molecular properties that are novel for experimentally determined charge densities are computed, including Weinhold population analysis, Mayer bond orders, and local kinetic energy densities, in addition to charge topological analysis and quantum theory of atoms-in-molecules (QTAIM) integrated properties. The ease with which a distributed multipole analysis can be performed on the fitted density matrix makes it straightforward to compute molecular moments, the lattice energy, and the electrostatic interaction energies of molecules removed from the crystal. Results are compared with high-level (QCISD) gas-phase calculations and band structure calculations employing density functional theory. Finally, the avenues available for extending the range of molecular properties that can be calculated from experimental charge densities still further using this approach are discussed. 相似文献
873.
稀土在中国高新材料研制开发中的应用 总被引:5,自引:1,他引:5
我国在稀土资源和稀土原料的生产方面都居世界领先地位,近年来稀土高新材料的研制与开发也取得重大进展。本文概述了我国在稀土高新材料开发与研究方面的成果,指出今后应把稀土应用基础研究、中重稀土的应用研究和稀土在能源领域的应用研究作为重点进一步开展工作。 相似文献
874.
The electrochemical behavior of a nickel electrode with limited volume (LVE) electrodeposited as a thin layer on gold has
been studied. The influence of the gold matrix on the electrochemical Ni electrode behavior has been considered. The electrosorption
and oxidation of carbon monoxide on the Ni surface and its influence on hydrogen sorption has also been demonstrated.
Received: 21 May 1997 / Accepted: 9 June 1997 相似文献
875.
超声催化反应的研究现状和发展趋势 总被引:25,自引:0,他引:25
综述了近几十年来超声在催化反应领域中的研究成果,包括超声在均相和多相催化反应中的应用,探讨了超声在催化反应领域中的发展趋势。 相似文献
876.
877.
Single phase of ammonium tetramolybdate in the micro power form was prepared from polyphase ammonium paramolybdate. Its heat capacity from 14.25℃ to 120.12 ℃ was measured by drop method and the result is
Cp=0.3936+7.4047×10-4T+6.3543×10-3T-2(J•K-1•g-1) 相似文献
Cp=0.3936+7.4047×10-4T+6.3543×10-3T-2(J•K-1•g-1) 相似文献
878.
铂单晶电极表面不可逆反应动力学I.Pt(100)单晶电极上甲酸氧化的现场红外反射光谱研究 总被引:4,自引:3,他引:4
运用电化学暂态方法和现场时间分辨FTIR反射光谱研究甲酸在Pt(100)单晶电极上的解离吸附和氧化过程,深入认识了甲酸解离吸附的反应速率在-0.25至0.25V电位区间呈火山形变化的规律。根据电化学现场时间分辨红外光谱的研究结果,提出在研究反动力学时避免甲酸解离吸附干扰的方法,为进一步研究甲酸在Pt(100)电极表面经活性中间体直接氧化至CO2的反应动力学奠定了基础。 相似文献
879.
分析化学样品前处理技术研究进展 总被引:1,自引:0,他引:1
综述分析化学中样品前处理技术的重要地位、分类及研究进展情况,并对超临界流体萃取等几种近年来发展较快的样品前处理新方法的原理及特点作了介绍。这些技术能够有效地减少分析过程中由样品前处理过程带来的误差,具有前处理快速、简便的优点,同时可与分析仪器联用,实现分析的自动化。 相似文献
880.
The thermal decomposition of cobalt acetate tetrahydrate (Co(CH3COO)2 · 4H2O) has been studied via thermogravimetric (TG) analysis, in situ X-ray powder diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results of TG and XRD showed that
the parent salt melted and then the dissolved crystalline water was vaporized in two steps. The dehydration process was followed
by a major step concerning the decomposition of the acetate group, leading to basic acetate as an intermediate, which then
produced CoO and Co in N2 and H2 atmosphere, respectively. Three decomposition intermediates Co(CH3COO)2 · 0.5H2O, Co(CH3COO)2, and Co(OH)(CH3COO) were presumed. In situ XRD experiments revealed that the intermediate basic acetate was poorly crystallized or even amorphous. Evolved gases analysis
indicated that the volatile products of acetate decomposition were water vapor, acetic acid, ethylenone, acetone, and CO2. A detailed thermal decomposition mechanism of Co(CH3COO)2 · 4H2O was discussed. 相似文献