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2.
Photo-Induced Switching of CO2 Hydrogenation Pathway towards CH3OH Production over Pt@UiO-66-NH2(Co)
Dr. Jianmin Chen Dr. Yajing Wang Dr. Fengliang Wang Prof. Yingwei Li 《Angewandte Chemie (International ed. in English)》2023,62(9):e202218115
It is highly desired to achieve controllable product selectivity in CO2 hydrogenation. Herein, we report light-induced switching of reaction pathways of CO2 hydrogenation towards CH3OH production over actomically dispersed Co decorated Pt@UiO-66-NH2. CO, being the main product in the reverse water gas shift (RWGS) pathway under thermocatalysis condition, is switched to CH3OH via the formate pathway with the assistance of light irradiation. Impressively, the space-time yield of CH3OH in photo-assisted thermocatalysis (1916.3 μmol gcat−1 h−1) is about 7.8 times higher than that without light at 240 °C and 1.5 MPa. Mechanism investigation indicates that upon light irradiation, excited UiO-66-NH2 can transfer electrons to Pt nanoparticles and Co sites, which can efficiently catalyze the critical elementary steps (i.e., CO2-to-*HCOO conversion), thus suppressing the RWGS pathway to achieve a high CH3OH selectivity. 相似文献
3.
Shaik Inayath Basha Atta Ur Rehman Hammad R. Khalid Md. Abdul Aziz Jung-Hoon Kim 《Chemical record (New York, N.Y.)》2023,23(10):e202300054
Three-dimensional (3D) geopolymer printing (3DGP) technology is a rapidly evolving digital fabrication method used in the construction industry. This technology offers significant benefits over 3D concrete printing in terms of energy saving and reduced carbon emissions, thus promoting sustainability. 3DGP technology is still evolving, and researchers are striving to develop high-performance printable materials and different methods to improve its robustness and efficiency. Carbon-based nanomaterials (CBNs) with beneficial properties have a wide range of applications in various fields, including as concrete/geopolymer systems in construction. This paper comprehensively reviews the research progress on carbon-based nanomaterials (CBNs) used to develop extrusion-based 3D geopolymer printing (3DGP) technology, including dispersion techniques, mixing methods, and the materials′ performance. The rheological, mechanical, durability, and other characteristics of these materials are also examined. Furthermore, the existing research limitations and the prospects of using 3DGP technology to produce high-quality composite mixtures are critically evaluated. 相似文献
4.
中性墨水属于热力学上不稳定的颜料悬浮体系,选择低黏度、高稳定性的色浆是保证墨水体系分散稳定性的重要手段之一。基于此,以颜料炭黑和酞菁蓝为着色剂,配合超分散剂(EK43)与协同增效剂(BM10),制备了两款适用于中性墨水体系的无树脂色浆。首次从色浆粒径与体系分散稳定性角度出发,确定了EK43、BM10用量以及最佳研磨时间,并对其理化性能、稳定性与书写性能进行分析测试。结果表明:在黑色浆中添加质量分数10.0%的EK43、2.5%的BM10,研磨时间为90 min;在蓝色浆中添加质量分数8.0%的EK43、2.0%的BM10,研磨时间为120 min时,两种色浆的粒径与分散稳定性均达到最佳。所制备的无树脂色浆颜料固含量高、黏度较低、储存稳定性好、着色力强,以其调配的中性墨水书写性能良好,且具有较好的离心稳定性和耐热稳定性。 相似文献
5.
Isothermal solubility of 2-(3,4-Dimethoxyphenyl)-5,6,7,8-tetramethoxychromen-4-one (nobiletin) in supercritical carbon dioxide at temperatures of (313, 323 and 333) K and pressures from (18 to 31) MPa was measured using an analytic-recirculation methodology, with direct determination of the molar composition of the carbon dioxide-rich phase by using high performance liquid chromatography. Results indicated that the range of the measured solubility of nobiletin was from 107 · 10−6 mol · mol−1 at T = 333 K and 18.35 MPa to 182 · 10−6 mol · mol−1 at T = 333 K and 31.40 MPa, with a temperature crossover around 18 MPa. The validation of the experimental solubility data was carried out by using three approaches, namely, estimation of combined expanded uncertainty for each solubility data point from experimental parameters values (⩽77 · 10−6 mol · mol−1); thermodynamic consistency, verified utilizing a test adapted from tools based on Gibbs–Duhem equation and solubility modelling results; and, self-consistency, proved by correlating the solubility data with a semi-empirical model as a function of temperature, pressure and pure CO2 density. 相似文献
6.
Small concentrations (≤5 wt. %) of nanoparticles in polymeric materials can potentially result in improvements in material properties and functionality. However, poor or non-uniform particle dispersion resulting in clustering (agglomeration) in polymer nanocomposites (PNCs) limits the potential for property enhancement. Achieving good dispersion is considered essential for large-scale production and commercialization of PNCs. New and effective measurement techniques capable of quantitatively characterizing particle loading and dispersion would significantly contribute towards understanding and optimizing the material performance of PNCs and, consequently, play a pivotal role in product development. This paper presents the results of a study using a static light scattering technique, optical wavefront correlation (OWC), for discriminating between different particle loadings and levels of dispersion. The technique has been applied to a range of PNCs, including epoxy resins reinforced with nanoclay platelets or silica microspheres, and zinc oxide and lithium aluminate reinforced polypropylene. 相似文献
7.
A single crystal of neodymium gallate was investigated by FTIR-spectroscopy in the reststrahlen region between 100–1000 cm−1. The three spectra of the crystal in principal orientations were analyzed by dispersion analysis and the dispersion parameters and the dielectric tensor function were obtained. This allows to properly characterize and quantitatively analyze films of this important substrate material by IR-optical methods. 相似文献
8.
J. M. P. Q. Delgado 《Heat and Mass Transfer》2006,42(4):279-310
The phenomenon of dispersion (transverse and longitudinal) in packed beds is summarized and reviewed for a great deal of information
from the literature. Dispersion plays an important part, for example, in contaminant transport in ground water flows, in miscible
displacement of oil and gas and in reactant and product transport in packed bed reactors. There are several variables that
must be considered, in the analysis of dispersion in packed beds, like the length of the packed column, viscosity and density
of the fluid, ratio of column diameter to particle diameter, ratio of column length to particle diameter, particle size distribution,
particle shape, effect of fluid velocity and effect of temperature (or Schmidt number). Empirical correlations are presented
for the prediction of the dispersion coefficients (D
T and D
L) over the entire range of practical values of Sc and Pem, and works on transverse and longitudinal dispersion of non-Newtonian fluids in packed beds are also considered. 相似文献
9.
The work is devoted to the problem of plane monochromatic longitudinal wave propagation through a homogeneous elastic medium
with a random set of spherical inclusions. The effective field method and quasicrystalline approximation are used for the
calculation of the phase velocity and attenuation factor of the mean (coherent) wave field in the composite. The hypotheses
of the method reduce the diffraction problem for many inclusions to a diffraction problem for one inclusion and, finally,
allow for the derivation of the dispersion equation for the wave vector of the mean wave field in the composite. This dispersion
equation serves for all frequencies of the incident field, properties and volume concentrations of inclusions. The long and
short wave asymptotics of the solution of the dispersion equation are found in closed analytical forms. Numerical solutions
of this equation are constructed in a wide region of frequencies of the incident field that covers long, middle, and short
wave regions of propagating waves. The phase velocities and attenuation factors of the mean wave field are calculated for
various elastic properties, density, and volume concentrations of the inclusions. Comparisons of the predictions of the method
with some experimental data are presented; possible errors of the method are indicated and discussed. 相似文献
10.
基于有限元法,设计了一种六边形排列含CdSe/ZnS量子点薄膜结构的高双折射光子晶体光纤,分析了具有不同厚度CdSe/ZnS量子点薄膜光子晶体光纤的色散及损耗特性.结果表明,含CdSe/ZnS量子点薄膜结构的光子晶体光纤在x和y方向均存在基模.当泵浦光波长逐渐增加时,具有相同厚度CdSe/ZnS量子点薄膜光子晶体光纤的双折射值逐渐增大,x和y方向总色散先增大后减小且存在两个零色散点,损耗逐渐增大并在可见光波段趋近于零;具有不同厚度CdSe/ZnS量子点薄膜光子晶体光纤随CdSe/ZnS量子点薄膜厚度的增加,在相同泵浦光波长处,双折射值逐渐减小,x和y方向总色散逐渐减小且两个零色散点逐渐靠近,损耗逐渐增大.通过沉积不同厚度CdSe/ZnS量子点薄膜和选择合适泵浦光波长,可有效控制光子晶体光纤的色散和损耗. 相似文献