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41.
Carter JA Zaug JM Nelson AJ Armstrong MR Manaa MR 《The journal of physical chemistry. A》2012,116(20):4851-4859
Shock compression studies of pressed and confined ultrafine 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) powder were conducted using ultrashort ~300 ps, ~50 GPa shock waves. The recovered decomposition products were characterized using X-ray photoelectron spectroscopy, infrared spectroscopy, and Raman spectroscopy. A substantial amount of shock-related chemistry was observed. Approximately 75% of the nitrogen atoms were liberated as gas-phase species, along with ~33% of the oxygen atoms, as a result of the applied shock. Furthermore, we observe C 1s binding energies suggesting the formation of sp(3) hybridized amorphous carbon. For comparison, a carbon nitride material was also prepared and characterized by thermally pyrolizing TATB. The shock-compressed TATB and the thermally pyrolized TATB are qualitatively different, suggesting that, carbon nitrides, a possible indicator of nitrogen-rich heterocycles precursors, are not a major product class for strongly overdriven shock conditions. These experimental conditions were, however, not detonation conditions, and the possible formation of nitrogen-rich heterocycles in actual detonations still exists. 相似文献
42.
R. Eder C. J. Ashworth I. Berkes D. E. Brown U. Daemmrich I. S. Grant A. G. Griffiths E. Hagn R. Hassani P. Herzog S. Ohya M. Massaq C. Richard-Serre J. Rikovska K. Schloesser N. Severijns N. J. Stone W. Vanderpoorten J. Vanhaverbeke L. Vanneste T. Woelfle E. Zech Isolde Collaboration 《Hyperfine Interactions》1988,43(1-4):469-472
Nuclear orientation and nuclear magnetic resonance experiments were performed on185, 187, 189Pt isotopes oriented in Fe and single crystal Zn at temperatures down to about 6 mK. The hyperfine splitting frequencies of185Pt and187Pt in iron were determined to be 164.9(2) and 261.1(2) MHz, respectively. With the hyperfine field of −126.1(2.5) T, the g-factors
are deduced to be |g(185Pt)|=0.172(3) and |g(187Pt)|=0.272(5).
The spectroscopic quadrupole moment of187Pt was found to be negative with magnitude similar to that of189Pt, indicating a predominantly oblate ground state deformation for both isotopes. The spectroscopic quadrupole moment of185Pt was found to be positive, with the ratio Q(185Pt)/Q(189Pt)=−3.6(9), clearly indicating a change to prolate ground state deformation. 相似文献
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Norbert Kuhn Riad Fawzi Manfred Steimann Jrg Wiethoff Gerald Henkel 《无机化学与普通化学杂志》1997,623(10):1577-1582
Synthesis and Structure of [ImNCS2K] (ImN = 1,3-Dimethylimidazoline-2-imino): a Novel Potassium Dithiocarbiminate The reaction of the 2-iminoimidazoline 4 with KMe gives the potassium imidate 7 from which the potassium 1,1-dithiolate 8 is obtained in almost quantitative yield. Crystals of C6H8N3S2K · 1/6 CH3CN ( 8 · 1/6 CH3CN) are triclinic, space group P1 , Z = 6, a = 10.988(4), b = 13.597(8), c = 13.622(9) Å, α = 113.003, β = 105.53(3), γ = 105.62(3)°, V = 1636.90 Å3. The structure consists of a complicated 3-dimensional framework in which the K2 units bridged by the four sulfur atoms of two thiolate ligands are connected by nitrogen and sulfur bridges. 相似文献
47.
Mahboube Shirani Ali Akbari Mohsen Hassani Alireza Goli Saeed Habibollahi Parisa Akbarian 《International journal of environmental analytical chemistry》2018,98(3):271-285
Facile and potent homogeneous liquid–liquid microextraction via flotation assistance method (HLLME-FA) combined with gas chromatography-mass spectrometry was proposed for determination of trace amounts of myclobutanil in fruit and vegetable samples. The paramount parameters, such as extraction and homogeneous solvent types and volumes, ionic strength and extraction time were studied. Under optimum conditions, the detection limit of 0.005 ng g?1, the linear range of 0.05–100 ng g?1, and the precision of 3.8% were acquired. A three-layer arti?cial neural network (ANN) model was used with 10 neurons and tan-sigmoid function at hidden layer and a linear transfer function at output layer were developed to predict the process. The results indicated that the proposed ANN model could perfectly predict the process with the mean square error of 0.89%. Then genetic algorithm was utilised to optimise the parameters. The proposed procedure showed satisfactory results for analysis of cucumber, tomato, grape, and strawberry. 相似文献
48.
In order to find informations on the native structure of the Leu-Enkephalin opiate peptide, the parent peptide and its two thioamide analogs (Thio-Gly2)Leu-Enkephalin and (Thio-Gly3)Leu-Enkephalin were studied by the theoretical method PEPSEA. This comparative conformational analysis showed that the active conformation is a β turn structure centered on Gly3 and Phe4. Moreover, this study showed also that the more active analog (Thio-Gly2)Leu-Enk has a lower tendency to adopt this structure. Consequently, its high activity can only be explained by its long lifetime due to its resistance to enzymatic hydrolysis, following the substitution of the amide linkage by the thioamide one. The weakly active analog (Thio-Gly3)Leu-Enk does not adopt this structure and prefers instead a β turn structure centered on Gly2 and Gly3. This study also confirmed the importance of the distances between the Tyr and Phe residues at positions 1 and 4, and that of the terminal Tyrosine N-H group which must be free of any intramolecular hydrogen bond in order to be available in the molecular recognition process. 相似文献
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Ekkehard Lindner Faouzi Bouachir Riad Fawzi Dieter Hubner 《Journal of organometallic chemistry》1982,235(3):345-352
The platinacyclopentane derivative [Cl(CH2)3R2P](Cl) is formed by action of Cl(CH2)3PR2 on Pt(COD)2 in n-hexane via the not isolable Pt[PR2(CH2)3Cl]2 (R C6H11) by oxidative addition of a CCl bond to platinum. [μ-CIRh(CO)2]2 reacts in benzene with Cl(CH2)3PR2 under partially CO substitution to give the stable intermediate Cl(OC)Rh[PR2(CH2)3Cl]2. In boiling toluene oxidative addition of a CCl bond to rhodium occurs under formation of the phospharhodacyclopentane [CI(CH2)3R2P] Cl2(OC)- (R C6H5). The 31P{1H}-NMR spectra of the rhodium compound is characterized by an ABX system, that of the platinum by superposition of an ABX pattern with an AB spectrum. 相似文献