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991.
992.
利用高能离子研究了110 keV的He+注入Al2O3单晶及随后230 MeV的208pb27+辐照并在不同温度条件下退火样品的光致发光的特性.从测试结果可以清楚地看到在375 nm,390 nm,413 nm和450 nm出现了强烈的发光峰.经过600 K退火2 h后测试结果显示,390 nm发光峰增强剧烈,而别的发光峰显示不明显.在900 K退火条件下,390 nm的发光峰开始减弱相反在510 nm出现了较强的发光峰,到1100 K退火完毕后390 nm的发光峰完全消失,而510 nm的发光峰相对增强.从辐照样品的FTIR谱中看到,波数在460-510 cm-1间的吸收是振动模式,经过离子辐照后,吸收带展宽,随着辐照量的增大,Al2O3振动吸收峰消失,说明Al2O3振动模式被完全破坏.1000-1300cm-1之间为Al-O-Al桥氧的伸缩振动模式,辐照后吸收带向高波数方向移动.退火后的FTIR谱变化不大. 相似文献
993.
The spt-crank of a vector partition, or an S -partition, was introduced by Andrews, Garvan and Liang. Let NS(m,n) denote the net number of S-partitions of n with spt-crank m, that is, the number of S -partitions (π1,π2,π3) of n with spt-crank m such that the length of π1 is odd minus the number of S -partitions (π1,π2,π3) of n with spt-crank m such that the length of π1 is even. Andrews, Dyson and Rhoades conjectured that {NS(m,n)}m is unimodal for any n , and they showed that this conjecture is equivalent to an inequality between the rank and crank of ordinary partitions. They obtained an asymptotic formula for the difference between the rank and crank of ordinary partitions, which implies NS(m,n)≥NS(m+1,n) for sufficiently large n and fixed m. In this paper, we introduce a representation of an ordinary partition, called the m-Durfee rectangle symbol, which is a rectangular generalization of the Durfee symbol introduced by Andrews. We give a proof of the conjecture of Andrews, Dyson and Rhoades. We also show that this conjecture implies an inequality between the positive rank and crank moments obtained by Andrews, Chan and Kim. 相似文献
994.
Dr. Zhennan Wu Dr. Qiaofeng Yao Osburg Jin Huang Chai Nan Ding Prof. Wen Xu Prof. Shuangquan Zang Prof. Jianping Xie 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(25):10020-10025
Aggregation-induced emission (AIE) provides an efficient strategy to synthesize highly luminescent metal nanoclusters (NCs), however, rational control of emission energy and intensity of metal NCs is still challenging. This communication reveals the impact of surface AuI-thiolate motifs on the AIE properties of Au NCs, by employing a series of water-soluble glutathione (GSH)-coordinated Au complexes and NCs as a model ([Au10SR10], [Au15SR13], [Au18SR14], and [Au25SR18]−, SR=thiolate ligand). Spectroscopic investigations show that the emission wavelength of Au NCs is adjustable from visible to the near-infrared II (NIR-II) region by controlling the length of the AuI-SR motifs on the NC surface. Decreasing the length of AuI-SR motifs also changes the origin of cluster luminescence from AIE-type phosphorescence to Au0-core-dictated fluorescence. This effect becomes more prominent when the degree of aggregation of Au NCs increases in solution. 相似文献
995.
Structures,Energetics, and Infrared Spectra of the Cationic Monomethylamine-Water Clusters
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Shu-kang Jiang Dong Yang Xiang-tao Kong Chong Wang Xiang-yu Zang Hui-jun Zheng Gang Li Hua Xie Wei-qing Zhang Xue-ming Yang Ling Jiang 《化学物理学报(中文版)》2020,33(1):31-36
The structures, energetics, and infrared (IR) spectra of the cationic monomethylamine-water clusters, [(CH\begin{document}$_3$\end{document} NH\begin{document}$_2$\end{document} )(H\begin{document}$_2$\end{document} O)\begin{document}$_n$\end{document} ]\begin{document}$^+$\end{document} (\begin{document}$n$\end{document} =1\begin{document}$-$\end{document} 5), have been studied using quantum chemical calculations at the MP2/6-311+G(2d,p) level. The results reveal that the formation of proton-transferred CH\begin{document}$_2$\end{document} NH\begin{document}$_3$\end{document} \begin{document}$^+$\end{document} ion core structure is preferred via the intramolecular proton transfer from the methyl group to the nitrogen atom and the water molecules act as the acceptor for the O\begin{document}$\cdots$\end{document} HN hydrogen bonds with the positively charged NH\begin{document}$_3$\end{document} \begin{document}$^+$\end{document} moiety of CH\begin{document}$_2$\end{document} NH\begin{document}$_3$\end{document} \begin{document}$^+$\end{document} , whose motif is retained in the larger clusters. The CH\begin{document}$_3$\end{document} NH\begin{document}$_2$\end{document} \begin{document}$^+$\end{document} ion core structure is predicted to be less energetically favorable. Vibrational frequencies of CH stretches, hydrogen-bonded and free NH stretches, and hydrogen-bonded OH stretches in the calculated IR spectra of the CH\begin{document}$_2$\end{document} NH\begin{document}$_3$\end{document} \begin{document}$^+$\end{document} and CH\begin{document}$_3$\end{document} NH\begin{document}$_2$\end{document} \begin{document}$^+$\end{document} type structures are different from each other, which would afford the sensitive probes for fundamental understanding of hydrogen bonding networks generated from the radiation-induced chemical processes in the [(CH\begin{document}$_3$\end{document} NH\begin{document}$_2$\end{document} )(H\begin{document}$_2$\end{document} O)\begin{document}$_n$\end{document} ]\begin{document}$^+$\end{document} complexes. 相似文献
996.
Li X Hihath J Chen F Masuda T Zang L Tao N 《Journal of the American Chemical Society》2007,129(37):11535-11542
We have studied electron transport through single redox molecules, perylene tetracarboxylic diimides, covalently bound to two gold electrodes via different linker groups, as a function of electrochemical gate voltage and temperature in different solvents. The conductance of these molecules is sensitive to the linker groups because of different electronic coupling strengths between the molecules and electrodes. The current through each of the molecules can be controlled reversibly over 2-3 orders of magnitude with the gate and reaches a peak near the redox potential of the molecules. The similarity in the gate effect of these molecules indicates that they share the same transport mechanism. The temperature dependence measurement indicates that the electron transport is a thermally activated process. Both the gate effect and temperature dependence can be qualitatively described by a two-step sequential electron-transfer process. 相似文献
997.
采用一种新型的电子传输材料TFTTP作为阴极缓冲层提高基于SubPc/C60异质结的有机薄膜太阳能电池的性能. 通过在有机活性层和金属电极之间加入TFTTP界面层,器件的能量转换效率提高了约30%. 系统研究了器件的二极管特性、光电流特性以及内部的光场分布情况,结果表明,TFTTP阴极缓冲层的引入可以有效地提高器件的内建电场,进而增加电荷转移激子的分离效率. 通过使用TFTTP作为阴极缓冲层,在C60/金属界面形成良好的欧姆接触,降低了界面接触电阻,有利于自由载流子的收集. 相似文献
998.
飞机雷击附着点的确定能够为飞机防雷设计提供依据,是飞机雷击区域划分和飞机各部件进行雷电试验鉴定的先决条件.本文提出了一种基于分形理论的飞机雷击初始附着点数值模拟的新方法.该方法首先依据标准SAE-ARP5416中有关飞机雷击附着点试验的规定,确定放电间隙、雷电起始坐标、飞机姿态和放电次数等参数,然后根据分形理论,使用电介质击穿模型模拟符合自然界雷电物理机理和几何特征的雷电先导分形发展过程,同时考虑飞机自身触发双向先导的情况,最终得到飞机的雷击附着点分布.通过本文方法仿真模拟得到飞机F-4雷击附着点的分布概率,并分别与该飞机飞行实验和实验室高压放电实验测试得到的真实雷击附着点的概率分布情况比较,结果基本吻合,验证了该方法的有效性.研究结果为飞机雷击附着点仿真模拟提供了一个有潜力的方法,可作为飞机防雷设计和今后开展相关研究工作的基础. 相似文献
999.
D.?Y.?Zang H.?P.?Wang F.?P.?Dai D.?Langevin B.?WeiEmail author 《Applied Physics A: Materials Science & Processing》2011,102(1):141-145
We report a solidification mechanism transition of liquid ternary Co45Cu45Ni10 alloy when it solidifies at a critical undercooling of about 344 K. When undercooling at ΔT<344 K, the solidification process is characterized by primary S (Co) dendritic growth and a subsequent peritectic transition.
The dendritic growth velocity of S (Co) dendrite increases with the rise of undercooling. However, once ΔT>344 K, the solidification velocity decreases with the increase of undercooling. In this case, liquid/liquid phase separation
takes place prior to solidification. The minor L2 (Cu) droplets hinder the motion of the solidification front, and a monotectic transition may occur in the major L1 phase. These facts caused by metastable phase separation are responsible for the slow growth at high undercoolings. 相似文献
1000.
Li B Zang SQ Ji C Liang R Hou HW Wu YJ Mak TC 《Dalton transactions (Cambridge, England : 2003)》2011,40(39):10071-10081
The reactions of 1,2,3,4-benzenetetracarboxylic acid (H(4)mpda) and different silver(I) salts under hydrothermal or solvent evaporation conditions yielded four unusual coordination complexes with interesting frameworks: [Ag(4)(mpda)](n) (1), {[Ag(2.5)(mpda)(bpy)(2)]·[Ag(bpy)]·[Ag(bpy)(H(2)O)]·(NO(3))(0.5)·(H(2)O)(9)}(n) (2), {[Ag(5)(mpda)(2)(bpy)(4)]·[Ag(bpy)]·[Ag(bpy)(H(2)O)]·[Ag(bpy)(H(2)O)]·(H(2)O)(16)}(n) (3), {[Ag(2)(mpda)(H(2)O)]·[Ag(bpy)]·[Ag(bpy)]}(n) (4) (bpy = 4,4'-bipyridine). Complex 1 displays a novel (3,4,7)-connected {4.6(2)}{4.6(5)}{4(2).6(13).8(5).10} topology, in which the carboxylic groups of the mpda(4-) ligand adopt variable coordination modes. In 1, besides Ag-O coordination bonding, AgAg and Agaromatic intermolecular interactions also make their appearance. In complexes 2-4, rare architectures comprising three or four isolated coordination polymers within the same crystalline structure have been obtained, respectively. In 2 and 3, neighboring layers are linked together through water tapes into a three-dimensional supramolecular architecture, which is also consolidated by π···π stacking, while independent infinite rod-like polymer chains fill the void space between layers. Interestingly, an anionic (H(2)O-NO(3)(-))(n) layer, built from water tapes and nitrate anions as well as consolidated by the mpda(4-) ligands, has been structurally identified in compound 2. A new water tape constructed from alternating tetramers and decamers has been obtained in compound 3. In compound 4, a right-handed helical chain and two rod-like polymeric chains are interconnected through host-guest molecular recognition to generate a three-dimensional chiral supramolecular architecture. Bulk materials for 1 and 4 have second-harmonic generation activity, being approximately 0.6 and 0.4 times that of urea. The IR spectra, thermogravimetric analysis and luminescent properties of all compounds were also investigated. 相似文献