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51.
Li W Liu X Hao X Hu X Chu Y Cao W Qin S Hu C Lin L Feng X 《Journal of the American Chemical Society》2011,133(39):15268-15271
α-Diazoesters were discovered to be good electrophiles in a catalytic asymmetric α-functionalization of ketones for the first time. This reaction also provided a direct and efficient method for C-N bond formation with excellent yields (up to 98%) and enantioselectivities (up to 99% ee) under mild conditions. The application of the electrophilicity of α-diazoesters opens up a novel way to access the diversity of diazo chemistry. 相似文献
52.
齐昌伟 《核聚变与等离子体物理》1993,13(2):62-64
在稳态托卡马克堆的燃烧阶段,当感应电流下降后,新经典输运产生的自举电流便成为维持稳定电流的最好手段。本文根据α粒子新经典自举电流的最新结果,计算了感应电流消失阶段,稳态堆中α粒子、电子和离子的自举电流。 相似文献
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The fastness and robustness of a control algorithm are highly important in the performance of adaptive optics systems. The proportional-integral-derivative control with arranging the transient process, which is designed using a tracking differentiator, is applied into an adaptive optics system. This control algorithm greatly improves the dynamic properties of the control system. To identify the underlying reasons for these improvements, the influence of the control algorithm is theoretically discussed. The control algorithm is verified by a simple adaptive optics system for tip/tilt correction. The experimental results demonstrate that the control algorithm is fast and robust. 相似文献
55.
Yu Huimei Qi Lingjun Zhang Qinghong Jiang Danyu Lu Changwei 《Journal of Thermal Analysis and Calorimetry》2011,106(1):47-52
The thermal behavior of the anticancer drug-irinotecan was measured by Thermogravimetry–Differential thermal analysis (TG–DTA)
to explore the application of TG–DTA in nanomedicine firstly. The TG–DTA result showed that the irinotecan was oxidized completely
before 700 °C. When irinotecan was loaded onto nanosized mesoporous silica spheres, the loading capacity for irinotecan measured
by TG–DTA was about 9.11% in the irinotecan/mesoporous SiO2 composite, similar to the typical UV–Vis spectra results (10.5%), which showed that TG–DTA characterization provided an alternative
method to determine the drug loading amount on inorganic carriers. Secondly, Thermogravimetry–Differential scanning calorimetry–Mass
Spectrometry coupling techniques (TG–DSC–MS) were used to characterize the hydrogen adsorption temperature and capacity of
TiCr1.2 (V-Fe)0.6 alloy. The MS result showed that the released region of hydrogen was 250–500 °C, which was consistent with the TG–DSC results.
Lastly, TA–MS combined with pulse thermal analysis (PulseTA) were used for a simultaneous characterizing study in the changes
of mass, determination and quantitative calibration of the evolved nitrogen formed during the thermal decomposition of the
InN powder. The results showed that relative error of this method between measured value and theoretical value was 2.67% for
the quantitative calibration of evolved N2. It shows that TA–MS combined with PulseTA techniques offer a good tool for the quantification of the evolved nitrogen in
the InN powder. 相似文献
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A highly efficient cross-coupling of diarylborinic acids and anhydrides with aryl chlorides and bromides has been effected by using a palladium catalyst system co-supported by a strong σ-donor N-heterocyclic carbene (NHC), N,N'-bis(2,6-diisopropylphenyl) imidazol-2-ylidene, and a strong π-acceptor phosphite, triphenylphosphite, in tert-BuOH in the present of K(3)PO(4)·3H(2)O. Unsymmetrical biaryls with a variety of functional groups could be obtained in good to excellent yields using as low as 0.01, 0.2-0.5, and 1 mol % palladium loadings for aryl bromides and activated and deactivated aryl chlorides, respectively, under mild conditions. A ligand synergy between the σ-donor NHC and the π-acceptor phosphite in the Pd/NHC/P(OPh)(3) catalytic system has been proposed to be responsible for the high efficacy to arylchlorides in the cross-coupling. A scalable and economical process has therefore been developed for synthesis of Sartan biphenyl from the Pd/NHC/P(OPh)(3) catalyzed cross-coupling of di(4-methylphenyl)borinic acid with 2-chlorobenzonitrile. 相似文献
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2-氨基吡啶金属配合物对羧酸酯水解的催化作用 总被引:5,自引:0,他引:5
合成了2-氨基吡啶(2-AP)为配体的Zn(2-AP)2(OAc)2,Ni(2-AP)2(OAc)2和Cu(2-AP)2(OAc)2三种金属配合物,并将其用于催化2-吡啶甲酸对硝基苯酚酯(PNPP)和乙酸对硝基苯酚酯(PNPA)的水解反应. 研究了金属配合物催化PNPP水解的动力学,提出了可能的催化机理. 结果表明,Zn(2-AP)2(OAc)2和Ni(2-AP)2(OAc)2金属配合物对PNPP水解反应有显著的催化作用,且Ni(2-AP)2(OAc)2的催化活性大于Zn(2-AP)2(OAc)2,而对PNPA无催化活性. Cu(2-AP)2(OAc)2对PNPP和PNPA均无催化活性. 这可能源自底物本身的特性以及配合物结构的差异. 同时,实验结果也说明合成的Zn(2-AP)2-(OAc)2和Ni(2-AP)2(OAc)2是水解金属酶的良好模型. 相似文献