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621.
622.
623.
Chil-Chyuan Kuo 《Journal of Russian Laser Research》2009,30(1):12-20
A real-time in-situ time-resolved (~1 ns) optical reflectivity and transmission (TRORT) measurement system combining two He–Ne
probe lasers, a digital oscilloscope, and three fast photodiodes is developed to investigate the rapid phase-change processes
of Si thin films during the excimer-laser crystallization (ELC). The changes in both reflectivity and transmission of Si thin
films during ELC are recorded by the TRORT measurement system. Melting and resolidification behaviors of Si thin films during
ELC are interpreted. The fall time of liquid Si is reduced with increase in the excimer-laser energy density, while the rise
time of liquid Si remains approximately constant at 5 ns. The first small peak in the reflectivity spectrum is proved to be
not a phenomenon of explosive crystallization. 相似文献
624.
J. -Un Nabi 《The European Physical Journal A - Hadrons and Nuclei》2009,40(2):223-230
During the presupernova evolution of massive stars, the isotopes of iron, 54, 55, 56Fe , are advocated to play a key role inside the cores primarily decreasing the electron-to-baryon ratio (Ye) mainly via electron capture processes thereby reducing the pressure support. Electron decay and positron capture on 55Fe , on the other hand, also have a consequential role in increasing the lepton ratio during the silicon burning phases of
massive stars. The neutrinos and antineutrinos produced, as a result of these weak-interaction reactions, are transparent
to the stellar matter and assist in cooling the core thereby reducing the entropy. The structure of the presupernova star
is altered both by the changes in Ye and the entropy of the core material. The aim of this paper is to report the improved microscopic calculation of Gamow-Teller
(GT±) strength distributions of these key isotopes of iron using the pn-QRPA theory. The main improvement comes from the incorporation
of experimental deformation values for these nuclei. Additionally six different weak-interaction rates, namely electron and
positron capture, electron and positron decay, and, neutrino and antineutrino cooling rates, were also calculated in presupernova
matter. The calculated electron capture and neutrino cooling rates due to isotopes of iron are in good agreement with the
large-scale shell model (LSSM) results. The calculated beta decay rates, however, are suppressed by three to five orders of
magnitude. 相似文献
625.
采用理想流体对称碰撞模型,分析了爆炸焊接流场中沿流线的物理变形,推导出了角变形的理论计算公式,并采用Visual C++语言对其进行了编程计算,获得了驻点近区角变形的大小及变化规律。结果表明,在驻点近区,沿来流至出流方向角变形逐步增大,其变化率在驻点附近最大;沿出流方向,给定碰撞角,角变形随来流速度的增加而增大;给定来流速度,角变形随碰撞角的增大而减小。从理论和实验方面,间接地将计算结果与前人的结论进行了对比验证,结果是一致的,以此为基础配合驻点近区的应变率场,讨论了其对爆炸焊接波状界面形成的影响。 相似文献
626.
炸药柱限定性热爆炸实验研究 总被引:1,自引:0,他引:1
在Frank kamenetskii热平衡方程基础上建立了二个 12 .7mm 2 5 .4mm炸药柱的限定性热爆炸实验装置、实验条件和实验方法 ,用于测定限定性热爆炸临界温度、反应延滞期 ,评价限定性热爆炸实验的反应水平。对于PBX 1炸药 ,限定性热爆炸的临界温度为 189 5℃ ,而30mm 30mm的炸药柱非限定热爆炸的临界温度为 197 5℃ ,表明在限定性体系中 ,由于炸药柱限定在金属铝的反应器里 ,热分解产物不易逸出 ,热量不易向环境传递 ,比非限定性体系易达到热爆炸临界条件 ,使热爆炸临界温度降低。此外 ,在相同环境温度下 ,PBX 6炸药柱的热爆炸延滞期比PBX 1炸药柱短 ,表明PBX 6炸药柱的热感度高 ,安全性低。 相似文献
627.
628.
激光速度干涉仪测量法在炸药圆筒试验中的应用 总被引:6,自引:1,他引:5
在炸药标准圆筒试验中 ,除了使用电探针测量炸药爆速、用高速相机记录圆筒膨胀过程的传统试验方法外 ,还用激光速度干涉仪 (VISAR)直接测量圆筒表面速度。根据圆筒试验的二维爆轰数值模拟分析结果 ,分析比较了高速相机和激光速度干涉仪的测量结果。 相似文献
629.
Two isostructural metal-organic frameworks,[NO3][M3(H2O)3O(TBA)3]-2DMF-6H2O(1 and 2)[M=In and Fe, H2TBA=4-(1H-tetrazol-5-yl)-benzoic acid], have been successfully synthesized. Compounds 1 and 2 have three-dimensional structures bridged via the typical 6-connected tri-nuclear cluster units M3O(COO)6 and linear linker H2TBA. The whole 3D framework possesses a 6-connected acs topology. Notably, by the fluorescence technique, compound 1 can detect nitro explosives through fluorescence quenching effect, especially for 2,4,6-trinitrophenol(TNP, Ksv=3.64×10^4 L/mol). Furthermore, the fluorescence spectrum red shifts as the number of NO2 group increases. Based on the aforementioned consideration, compound 1 can be considered as a potential luminescent probe for the detection of TNP. 相似文献
630.
The bromo‐substituted aromatic dicarboxylic acid 5‐amino‐2,4,6‐tribromoisophthalic acid (H2ATBIP), in the presence of the N‐donor flexible bipyridyl‐type ligands 1,3‐bis(pyridin‐4‐yl)propane (bpp) and N,N′‐bis(pyridin‐4‐ylmethyl)oxalamide (4‐bpme) and ZnII ions, was used as an O‐donor ligand to assemble two novel luminescent metal–organic frameworks (MOFs), namely poly[[(μ‐5‐amino‐2,4,6‐tribromoisophthalato‐κ2O1:O3)[μ‐1,3‐bis(pyridin‐4‐yl)propane‐κ2N:N′]zinc(II)] dimethylformamide monosolvate], {[Zn(C8H2Br3NO4)(C13H14N2)]·C3H7NO}n, ( 1 ), and poly[[(μ‐5‐amino‐2,4,6‐tribromoisophthalato‐κ2O1:O3)diaqua[μ‐N,N′‐bis(pyridin‐4‐ylmethyl)oxalamide‐κ2N:N′]zinc(II)] monohydrate], {[Zn(C8H2Br3NO4)(C14H14N4O2)(H2O)2]·H2O}n, ( 2 ), using the solution evaporation method. Both ( 1 ) and ( 2 ) were characterized by FT–IR spectroscopy, elemental analysis (EA), solid‐state diffuse‐reflectance UV–Vis spectroscopy, and powder and single‐crystal X‐ray diffraction analysis. Complex ( 1 ) shows a two‐dimensional (2D) corrugated layer simplified as a 2D (4,4) topological network. The supramolecular interactions (π–π stacking, hydrogen bonding and C—Br…Br halogen bonding) play significant roles in the formation of an extended three‐dimensional (3D) supramolecular network of ( 1 ). Complex ( 2 ) crystallizes in the chiral space group P212121 and exhibits a novel 3D homochiral framework, showing a diamond‐like topology with Schläfli symbol 66. The homochirality of ( 2 ) is further confirmed by the solid‐state circular dichroism (CD) spectrum. The second harmonic generation (SHG) property of ( 2 ) was also investigated. The hydrogen and C—Br…Br/O halogen bonding further stabilize the framework of ( 2 ). The central ZnII ions in ( 1 ) and ( 2 ) show tetrahedral and octahedral coordination geometries, respectively. The coordinated and uncoordinated water molecules in ( 2 ) could be removed selectively upon heating. Most importantly, ( 1 ) and ( 2 ) show rapid and highly sensitive sensing for a large pool of nitroaromatic explosives (NAEs). 相似文献