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131.
132.
Akshay Gopan Zhiwei Yang Richard L. Axelbaum 《Proceedings of the Combustion Institute》2019,37(4):4427-4434
Particle deposition on heat exchanger tubes is a serious concern in solid fuel combustion and gasification systems, such as power plants and syngas coolers. To predict deposition rates, several detailed computational fluid dynamic (CFD) models have been developed. However, these models are computationally expensive and cannot be used for quick determination of deposition rates and/or slagging tendencies. Particle impaction efficiency correlations, while not as accurate as detailed CFD models, are easier to use and are able to estimate the impaction rate of particles on the heat exchanger tubes. Nonetheless, since deposition and slagging are not just functions of particle impaction rates, but also sticking propensity, which is related to the particle temperature at impact, the impaction efficiency correlations fail to provide sufficient information. To address this shortcoming, similar correlations for particle temperature at impact have been developed in this work, based on a non-dimensional parameter that captures the flow and boundary conditions, as well as particle properties. When used alongside the impaction efficiency correlations, the new correlations developed can provide a reasonable estimate of the deposition and slagging tendencies, at negligible computational expense. 相似文献
133.
在理论分析的基础上,模拟研究了微电真空太赫兹器件Clinotron。求解了色散方程,获得该器件的基本结构参数和性能参数;在考虑空间电荷场和电子回旋运动的情况下,得出能使器件内片状束稳定传输的周期永磁聚焦的磁场条件;利用3维全电磁粒子模拟程序对Clinotron进行了初步模拟以及优化。数值模拟结果表明:当输入电压为4.5 kV、发射束流大小为190 mA、输入电功率为855 W时, 运行频率为218 GHz的Clinotron的输出平均功率40 W,功率转换效率达4.68%。 相似文献
134.
Construction of Hybrid Bimetallic Uranyl Compounds Based on a Preassembled Terpyridine Metalloligand
Xianghe Kong Dr. Kongqiu Hu Dr. Lei Mei Dr. Qunyan Wu Zhiwei Huang Kang Liu Prof. Zhifang Chai Prof. Changming Nie Prof. Weiqun Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(6):2124-2130
Six hybrid uranyl–transition metal compounds [UO2Ni(cptpy)2(HCOO)2(DMF)(H2O)] ( 1 ), [UO2Ni(cptpy)2(BTPA)2] ( 2 ), [UO2Fe(cptpy)2(HCOO)2(DMF)(H2O)] ( 3 ), [UO2Fe(cptpy)2(BTPA)2] ( 4 ), [UO2Co(cptpy)2(HCOO)2(DMF)(H2O)] ( 5 ), and [UO2Co(cptpy)2(BTPA)2] ( 6 ), based on bifunctional ligand 4′-(4-carboxyphenyl)-2,2′:6′,2′′-terpyridine (Hcptpy) are reported (H2BTPA = 4,4′-biphenyldicarboxylic acid). Single-crystal XRD revealed that all six compounds feature similar metalloligands, which consist of two cptpy− anions and one transition metal cation. The metalloligand M(cptpy)2 can be considered to be an extended linear dicarboxylic ligand with length of 22.12 Å. Compounds 1 , 3 , and 5 are isomers, and all of them feature 1D chain structures. The adjacent 1D chains are connected together by hydrogen bonds and π–π interactions to form a 3D porous structure, which is filled with solvent molecules and can be exchanged with I2. Compounds 2 , 4 , and 6 are also isomers, and all of them feature 2D honeycomb (6,3) networks with hexagonal units of dimensions 41.91×26.89 Å, which are the largest among uranyl compounds with honeycomb networks. The large aperture allows two sets of equivalent networks to be entangled together to result in a 2D+2D→3D polycatenated framework. Remarkably, these uranyl compounds exhibit high catalytic activity for cycloaddition of carbon dioxide. Moreover, the geometric and electronic structures of compounds 1 and 2 are systematically discussed on the basis of DFT calculations. 相似文献
135.
Hongmin Liu Xiaojiang Ye Zhiwei Lian Yuangao Wen Wenfeng Shangguan 《Research on Chemical Intermediates》2006,32(1):9-16
Formaldehyde is one of the most harmful pollutants that endanger occupants' health and the way of its effective removal has
become a focus in the field of air quality. This paper studies the static photocatalytic removal of formaldehyde experimentally
and finds out that carbon monoxide, which is more harmful to occupants' health than the formaldehyde itself, is one of the
by-products in the process of photocatalytic oxidation of formaldehyde. The increase of carbon monoxide concentration should
be taken into consideration in the photocatalytic application. The photocatalyst surface at room temperature can weakly adsorb
CO and CO2, which can deactivate the photocatalysts. 相似文献
136.
Tracking an active sound source involves the modeling of non-linear non-Gaussian systems. To address this problem, this paper proposed scaled unscented particle filter (SUPF) algorithm for tracking moving sound source. The particle filter part of the SUPF provides the general probabilistic framework to handle non-linear non-Gaussian systems, and the scaled unscented Kalman filter (SUKF) part of the SUPF generates better proposal distributions by taking into account the most recent observation. Meanwhile, models used in SUPF algorithm were also explored for the sound source motion, observation and the likelihood of the sound source location in the light of the Langevin process. Compared with the conventional PF approach, the simulated results demonstrated that the SUPF algorithm had superior tracking performance. 相似文献
137.
138.
139.
A new approach to realize high-energy and high-power stimulated Brillouin scattering phase conjugation mirrors (SBS-PCMs) is described.The reflectivity of SBS-PCM is investigated under a 10-Hz repetition rate and a high energy load.The relationship between reflectivity and input energy is examined experimentally with different PCM structures,focus lengths,and medium cell structures.A medium cell with a circulating structure is designed,and its advantage is demonstrated through an experimental comparison with traditional PCM structures.The 30-cm focus lens and 150-cm collimation lens are optimized when the input energy reaches 1010 mJ at 10-Hz repetition rate.Therefore,a reflectivity of 84.7% and a higher energy load using the circulating two-cell structure are achieved. 相似文献
140.
Wang X Xu X Zeng X Zhao Z Jiang B He X Xu J 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,63(1):49-54
Yb:YAG single crystals with Yb doping concentration 5.4, 16.3, 27.1, 53.6, and 100 at.% were grown by the Czochralski process. The effects of Yb concentration on the absorption spectra (190-1100 nm), fluorescence spectra under 940 nm and X-ray excitation were studied. The concentration quenching of fluorescence was observed when the Yb doping concentration reaches to as high as 27.1at.% for Yb:YAG. Under 940 nm excitation, the influence of the self-absorption at 969 and 1029 nm on the fluorescence spectra is not evident when the Yb doping concentration is as high as 27.1at.%. However, it can greatly change the shape of fluorescence spectra of Yb:YAG when the Yb doping concentration reaches to above 53.6 at.%. 相似文献