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51.
The equilibrium geometry and UV-visible spectra of C70 were examined using semiempirical INDO /2 and INDO /CI methods. The results obtained are in good accord with experimental results. On the basis of correct electronic spectra, calculations of the nonlinear third-order optical susceptibility (γijkl) of C70 were performed using the INDO /SDCI method combined with a sum-over-states expression. The calculated value for <γ> (-2 ω, ω, ω, O) is 0.882 × 10?33 esu (ω = 1.91 μm), which is in good agreement with observation. © 1994 John Wiley & Sons, Inc. 相似文献
52.
53.
3-羟基对氧萘酮分子内激发态质子转移反应位能面和机理的研究 总被引:1,自引:0,他引:1
封继康 《高等学校化学学报》1989,10(11):1114-1118
用MNDO和INDO-SCF-CI法研究了3-羟基对氧萘酮分子内激发态质子转移反应基态和激发态的位能面,求得相应能垒△E1、△E2和荧光移位,并对光化学反应机理进行了探讨. 相似文献
54.
Jikang Feng Aimin Ren Weiquan Tian Maofa Ge Zhiru Li Chiachung Sun Xuehe Zheng Michael C. Zerner 《International journal of quantum chemistry》2000,76(1):23-43
Possible isomers of Buckminsterfullerene derivatives C60O2 and C60O3 are studied with the semiempirical quantum mechanical INDO method. The C60O2 isomer of Cs symmetry, where the epoxy oxygen atoms are on the 6–6 bond of a hexagon, is found most stable. The C60O3 isomer of C3v symmetry with a single epoxy chain connecting both carbons of a 6–6 bond is most stable. However, the other two isomers of C2 and Cs symmetries are near as stable. In all cases, the 6–6 carbon–carbon bond in the epoxial ring is not broken. Based on the structures so identified, the calculated electronic spectra of C60O2, and the 13C‐NMR analysis of both C60O2 and C60O3 agree well with experiment. The calculated electronic spectra of C60O3 are theoretical prediction. The chemical reactivity of C60O2 and C60O3 is discussed in connection with our calculated results. © 1999 John Wiley & Sons, Inc. Int J Quant Chem 76: 23–43, 2000 相似文献
55.
用常压MOCVD装置,制备了透射式GaAs光电阴极材料。发射层P-型GaAs掺杂浓度到1018-1019cm-3,少子扩散长度到4.02μm。AlGaAs层的Al组分含量到0.83,其吸收光谱长波限与设计值基本符合。利用此材料进行了阴极激活实验,制成了透射式GaAs光阴极。 相似文献
56.
近年来,AgNWs(Ag Nanowires)透明电极由于良好的导电性、优秀的韧性,作为氧化铟锡(ITO)的替代材料受到了广泛的关注,可以用于多种电子设备,如触摸屏、有机太阳能电池和显示器等.但是,在近年的透明电极应用中,低长径比所带来的雾度过高、导电性较差的缺陷使AgNWs不能广泛地推广,所以提高长径比是迫在眉睫的.本文采用一步多元醇法制备AgNWs,探究不同分子量的混合PVP体系参与反应对包覆效果及生长过程的影响.研究结果表明,与单一分子量PVP体系相比,PVP混合体系在生长过程中的再次形核点减少,AgNWs的长径比更高;分子量为1 300 000与分子量为58 000的PVP按2∶1的比例混合,AgNWs宽度最小,长径比最高可达到1 200以上. 相似文献
57.
Deyi Shao Gang Gao Aminu Shehu Abubakar Hanipa Hazaisi Ping Chen Jikang Chen Kunmei Chen Xiaofei Wang Yue Wang Yu Chen Chunming Yu Aiguo Zhu 《Molecules (Basel, Switzerland)》2022,27(21)
In the current study, the total content from two Apocynum species leaves (Apocynum venetum and Apocynum hendersonii) collected from the Ili River Valley Region were extracted, and their bioactivities were investigated. The results showed a significant variation in the total flavonoid contents in the leaf samples collected at different periods (June, July, August, and September), with the highest content in August (60.11 ± 0.38 mg RE/g DW for A. venetum and 56.56 ± 0.24 mg RE/g DW for A. hendersonii), and the lowest in June (22.36 ± 0.05 mg RE/g DW for A. venetum and 20.79 ± 0.02 mg RE/g DW for A. hendersonii). The total flavonoid content was comparably higher in A. venetum than in A. hendersonii. Leaves extracts from the two species demonstrated strong bioactivity, which positively correlated with the total flavonoid contents. The anti-oxidative activity of A. venetum was higher than that of A. hendersonii in tandem with its higher flavonoid contents; the antibacterial activity, however, was conversely opposite. Furthermore, a total of 83 flavonoid metabolites were identified in the two species based on UPLC-ESI-MS/MS, out of which 24 metabolites were differentially accumulated. The variability in these metabolites might be the reason for the different bioactivities displayed by the two species. The present study provides insight into the optimal harvest time for Apocynum species planted in the major distribution area of the Ili River Valley and the specific utilization of A. venetum and A. hendersonii. 相似文献
58.
Yuming Zhou Weinan Leng Xiaojuan Liu Qunhua Xu Jikang Feng Juzheng Liu 《Journal of polymer science. Part A, Polymer chemistry》2002,40(14):2478-2486
Some thermally stable second‐order nonlinear optical (NLO) polyimides were synthesized. The polyimides were prepared by the ring‐opening polyaddition of 4,4′‐(hexafluoroisopropylidene) diphthalic anhydride and pyromellitic dianhydride with two aromatic azodiamine derivatives as the NLO chromophores. These chromophores, based on a nitro group connected with azobenzene as the acceptor end of a donor–π‐bridge–acceptor chromophore and a diamine group as the donor end, had specific chemical stability. On the basis of ZERNER'S INDO methods, according to the sum‐over‐states formula, a program for the calculation of nonlinear second‐order optical susceptibilities was devised. The resulting polyimides had high number‐average and weight‐average molecular weights of up to 26,000 and 53,500, respectively, and a large glass‐transition temperature of 248 °C. With an in situ poling and temperature ramping technique, the optimal temperatures (Topt's) for corona poling were obtained for the largest second‐order NLO response. The electrooptic coefficient (γ33) of a polyimide at a wavelength of 830 nm was up to 21 pm/V after corona poling under its Topt, and the value remained at elevated temperatures (>90.6% was retained at 240 °C for >120 h). The thermal stability of the NLO polyimides was studied with UV spectrometry after poling of the films. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2478–2486, 2002 相似文献
59.
Qiwen Teng Jikang Feng Chiachung Sun Michael C. Zerner 《International journal of quantum chemistry》1995,55(1):35-45
Intermediate neglect of differential overlap (INDO ) calculations were used to study two structures of C60NH: one of C2ν, geometry with a bridging NH across the bond between two fused six-membered rings in C60 and the other of Cs geometry with a bridging NH across the bond between a five- and a six-membered ring. We calculated the most stable isomer of C60NH to be of C2ν, symmetry. It was found that the C2ν isomer has a protonated aziridine structure with a bridging C? C bond length of 0.1520 nm. The electronic spectra of both isomers of C60NH were calculated. Comparisons were made with the isoelectronic molecules C60O and C60CH2, cases in which the calculated electronic spectra for the most stable isomers C60O (C2ν) and C60CH2 (C2ν) are in good agreement with recent experimental results. © 1995 John Wiley & Sons, Inc. 相似文献
60.
Cryptomelane-type manganese oxide octahedral molecular (OMS) sieve three-dimensional (3D) nanostructures were synthesized via facile temple-free low-temperature hydrothermal reactions. Morphologies of the cryptomelane-type OMS-2 nanoparticles with tunnel dimension of 4.6 x 4.6 A can be tuned by varying reaction temperatures. At low temperature (120 degrees C), OMS-2 dendritic nanoclusters composed of uniform single-crystal nanotetragonal prisms with square cross-sections were formed. At high temperature (180 degrees C), the morphologies of OMS-2 became spherical dandelion-like microspheres composed of uniform single-crystal OMS-2 nanoneedles. Slow oxidation of Mn(2+) by Cr(2)O(7)(-) under hydrothermal conditions is critical for the formation of the hierarchically ordered OMS-2 3D nanostructures. 相似文献