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991.
本文主要研究了不同水溶性离子对煅烧烟气脱硫石膏水化过程,也就是对大块煅烧石膏向石膏转化的相变过程的影响. 研究表明,在煅烧石膏向石膏转化的相变过程中,所有的阳离子都能加速煅烧石膏的水化作用,其中Ca2+的加速效应最弱. 对于最终沉淀得到的晶体,除了钠离子外,晶体尺寸不受不同种类盐的影响. 而在钠离子中,可以观察到长度大于130 μm的巨型结晶. 本研究阐明了不同离子对煅烧石膏水化的影响,为原始的烟气脱硫石膏在实际应用前的预处理提供了充分的指导. 相似文献
992.
《Current Applied Physics》2020,20(1):82-88
A detailed investigation about the effect of Sc2O3: 1 mol%Ho3+/5 mol%Yb3+ co-doped with Ce4+ ions prepared by sol-gel methods was performed systematically. Under the excitation of 980 nm laser diode, both green emission (553 nm, 5F4/5S2→5I8) and red emission (672 nm, 5F5→5I8) were both observed in the emission spectra of the samples, which were found to be two-photon process and sensitized by Yb3+ ions. With the increasing of Ce4+ ions, the up-conversion green emission intensity are increased by 6.52, 8.69, 10.85, 13.92 and 16.66 fold, corresponding to the Ce4+ ions concentrations from 5 mol% to 13 mol%, respectively. The number of photons are necessary to populate the upper emitting state decreases to 2 and the infrared absorption coefficient is reduced, when the Ce4+ ions concentration increase to 13 mol%. Ce4+ ions play an important role in tailoring the local crystal field around Ho3+ ions, lowering the highest phonon cut-off energy of matrix and reducing the infrared absorption coefficient, thus hindering the non-radiative processes, which contribute to the increased emission intensity. The excellent enhancement makes it a promising multifunctional optical luminescence material. 相似文献
993.
Jian-Ping Li Lian-Zhong Deng Ye Zheng Peng-Peng Ding Tian-Qing Jia Zhen-Rong Sun Jian-Rong Qiu Shi-An Zhang 《Frontiers of Physics》2020,15(2):22603-68
The spectral phase of the femtosecond laser field is an important parameter that affects the up-conversion(UC)luminescence efficiency of dopant lanthanide ions.In this work,we report an experi-mental study on controlling the UC lmiiinescence efficiency in Sm^3+:NaYF4 glass by 800-nm femtosec-ond laser pulse shaping using spectral phase modulation.The optimal phase control strategy efficiently enhances or suppresses the UC luminescence intensity.Based on the laser-power dependence of the UC luminescence intensity and its comparison with the luminescence spectrum under direct 266-nm fem-tosecond lciser irradiation,we propose herein an excitation model combining non-resonant two-photon absorption with resonance-media ted three-photon absorption to explain the experimental observations. 相似文献
994.
G. Szenes 《辐射效应与固体损伤》2020,175(3-4):241-256
ABSTRACTThe role of various materials parameters in track formation is discussed. Experimental information is utilized showing a direct quantitative relationship in different solids between the melting points Tm and the ion-induced track radii Re without involving other materials parameters. It is shown for Θ?=?Tm???Tir (Tir – irradiation temperature) that Θ~exp{?Re2/w2} for Se/N?=?constant, where Se and N are the electronic stopping power and the number density of atoms and w?=?4.5?nm. The validity of this universal-type relation is demonstrated for 14 different insulators including LiNbO3 and BaFe12O19. It is shown that the thermal diffusivity D, the heat of fusion L the band gap energy Eg and the absorption radius αe of the electron distribution must not affect the track sizes as this would not be coherent with this identical behavior. Original reports on LiNbO3 and BaFe12O19 with opposite conclusions are critically analyzed. It is shown that an arbitrary value of the ion energy was used in the analysis that modified substantially the results leading to an undue justification of the contribution of L and Eg in apparent agreement with the experimental data. 相似文献
995.
重元素高电离的离子特性对研究激光核聚变和X射线激光等都很重要,本文用3d^94s,3d^94d,3d^94p,3d^94f组态相互作用研究了类镍铱离子光谱跃迁。 相似文献
996.
997.
Dmitri V. Sevenard Peer Kirsch Enno LorkGerd-Volker Röschenthaler 《Tetrahedron letters》2003,44(32):5995-5998
With 2-trifluoromethyl-1,3-dithianylium triflate for the first time the synthesis, isolation and full structural characterization of an α-perfluoroalkylcarbenium salt was achieved. The title compound can be easily obtained on a preparative scale. The thermally stable dithianylium salt in combination with fluorodesulfurization chemistry is a promising novel reagent for the electrophilic polyfluoroalkylation of organic substrates, demonstrated by the pentafluoroethylation of O-nucleophiles. 相似文献
998.
I. A. Ivanov A. S. Kheifets 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(2):249-255
We apply a non-perturbative procedure for the calculation of the total
photoionization cross-section of two-electron atomic systems. The procedure is based on the Floquet-Fourier representation
of the time-dependent Schr?dinger equation. With the use of the Hylleraas-type basis functions, the total photoionization
cross-sections obtained are within the accuracy of a fraction of a percent, which, we believe, is the most accurate estimate
for the cross-sections available. The total photoionization cross-sections for neutral helium deviate notably from the benchmark
experimental data [J.A.R. Samson et al., J. Phys. B 27, 887 (1994)]. 相似文献
999.
1000.
用半径经典方法计算类Li离子电偶极跃迁的碰撞强度。用碰撞参数为b的双曲线轨道描述入射电子的运动,用时间有关的微扰理论方法描述靶态的跃迁几率,通过对碰撞参数的积分求出电子碰撞激发截面。碰撞强度可表示成与振子强度成线性关系的简单公式。计算了若干个类Li离子2s-2p1/2、2p3/2的碰撞强度。结果表明,除在阈能附近以外,大部分数据与用较精确的相对论扭曲波的计算结果符合得很好。所用方法简单,而且可以进行快速计算,有很大的实用价值和参考价值 相似文献