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71.
利用 10 0目~ 2 0 0目的硅胶 ,选择正戊烷和二氯甲烷作为洗脱剂 ,采用吸附色谱法将烷基苯生产中的循环烷烃分离为饱和烃 (烷烃 +环烷烃 )及芳烃两部分。然后将饱和烃及芳烃分别进行色谱 /质谱 (GC/MS)联用分析 ,得到了有关循环烷烃构成的定性定量结果。定性结果如实地反映出烷基苯生产中的副反应产物 ,可直接用于指导生产。从定量结果可以看出 ,经过硅胶吸附分离后 ,试样中含量要求很低的芳烃被浓缩 ,提高了分析的准确度和灵敏度 ,可以检测出循环烷烃中含量很低的物质 ,为全面分析样品组成提供了有力的证据。 相似文献
72.
Toward Naphthocyclinones: Doubly Connected Octaketide Dimers with a Bicyclo[3.2.1]octadienone Core by Thiolate‐Mediated Cyclization
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Dr. Yoshio Ando Subaru Hori Takumi Fukazawa Prof. Dr. Ken Ohmori Prof. Dr. Keisuke Suzuki 《Angewandte Chemie (International ed. in English)》2015,54(33):9650-9653
A viable method is reported for the synthesis of the bicyclo[3.2.1]octadienone scaffold in naturally occurring octaketide dimers. The procedure employs a reductive cyclization reaction mediated by an unusual ethanedithiol monosodium salt. 相似文献
73.
The novel substituted 2,3-dichloro-1,4-naphthoquinone derivatives were synthesized from the reactions of (1) and related nucleophilles in sodium carbonate (Na2CO3) solution of ethanol, chloroform with Et3N, or potassium carbonate (K2CO3) solution of acetonitrile. The structures of novel compounds were characterized by using microanalysis, Fourier transform–infrared, 1H NMR, 13C NMR, mass spectrometry, and cyclic voltammetry (CV).
[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] 相似文献
74.
Fully atomistic molecular‐mechanical model of liquid alkane oils: Computational validation
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Tsvetan K. Zahariev Radomir I. Slavchov Alia V. Tadjer Anela N. Ivanova 《Journal of computational chemistry》2014,35(10):776-788
Fully atomistic molecular dynamics simulations were performed on liquid n‐pentane, n‐hexane, and n‐heptane to derive an atomistic model for middle‐chain‐length alkanes. All simulations were based on existing molecular‐mechanical parameters for alkanes. The computational protocol was optimized, for example, in terms of thermo‐ and barostat, to reproduce properly the properties of the liquids. The model was validated by comparison of thermal, structural, and dynamic properties of the normal alkane liquids to experimental data. Two different combinations of temperature and pressure coupling algorithms were tested. A simple differential approach was applied to evaluate fluctuation‐related properties with sufficient accuracy. Analysis of the data reveals a satisfactory representation of the hydrophobic systems behavior. Thermodynamic parameters are close to the experimental values and exhibit correct temperature dependence. The observed intramolecular geometry corresponds to extended conformations domination, whereas the intermolecular structure demonstrates all characteristics of liquid systems. Cavity size distribution function was calculated from coordinates analysis and was applied to study the solubility of gases in hexane and heptane oils. This study provides a platform for further in‐depth research on hydrophobic solutions and multicomponent systems. © 2014 Wiley Periodicals, Inc. 相似文献
75.
76.
Schwertfeger H Fokin AA Schreiner PR 《Angewandte Chemie (International ed. in English)》2008,47(6):1022-1036
Marilyn Monroe knew that "diamonds are a girl's best friend" but, in the meantime, many chemists have realized that they are also extremely attractive objects in contemporary chemistry. The chemist's diamonds are usually quite small (herein: nanometer-sized "diamondoids") and as a result of their unique structure are unusual chemical building blocks. Since lower diamondoids (up to triamantane) have recently become available in large amounts from petroleum and higher diamondoids (starting from tetramantane) are now also accessible from crude oil new research involving them has begun to emerge. Having well-defined structures makes these cage compounds so special compared to other nanometer-scale diamonds. Selective and high-yielding synthetic approaches to the functionalization of diamondoids gives derivatives that can find applications in, for example, polymers, coating materials, drugs, and molecular electronics. 相似文献
77.
Chenxi Wen Ting Li Prof. Dr. Zheng Huang Prof. Dr. Qi-Kai Kang 《Chemical record (New York, N.Y.)》2023,23(11):e202300146
Preparing valuable olefins from cheap and abundant alkane resources has long been a challenging task in organic synthesis, which mainly suffers from harsh reaction conditions and narrow scopes. Homogeneous transition metals catalyzed dehydrogenation of alkanes has attracted much attention for its excellent catalytic activities under relatively milder conditions. Among them, base metal catalyzed oxidative alkane dehydrogenation has emerged as a viable strategy for olefin synthesis for its usage of cheap catalysts, compatibility with various functional groups, and low reaction temperature. In this review, we discuss recent development of base metal catalyzed alkane dehydrogenation under oxidative conditions and their application in constructing complex molecules. 相似文献
78.
The application of a new approach based on organic homo‐rank compounds and homologous compounds to the structure–property relationship study of mono‐substituted alkanes
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The two conceptual systems of organic homologous compounds and homo‐rank compounds give insight into the influence of structures on the properties of mono‐substituted alkanes Xi–(CH2)j–H from the transverse (change of repeating unit number j of CH2) and longitudinal (change of functional group Xi) perspectives, respectively. This paper aims to combine the organic homo‐rank compounds approach together with the homologous compounds approach to explore the property change rules of mono‐substituted alkanes involving various substituents. Firstly, based on the concept of organic homologous compounds, the properties of mono‐substituted straight‐chain alkane homologues were linearly correlated to the two‐thirds power of the number of carbon atoms (N2/3) in alkyl, and regression equations such as Q = A + BN2/3 were obtained. The regression coefficients A and B vary with different substituents Xi, so coefficients A and B were employed to characterize the structural information of substituent Xi. The structural features of alkyls (–(CH2)j–H, that is, –CjH2j+1) were described by the polarizability effect index (PEI(R)) and vertex degree–distance index (VDI). Then based on four parameters A, B, PEI(R), and VDI, quantitative structure–property relationship models were built for the boiling points (Bp) and refractive indexes (nD) of each mono‐substituted alkane homo‐rank series, where j = 3–10 and the substituents Xi involve F, Cl, Br, I, NO2, CN, NH2, COOH, CHO, OH, SH, and NC. Good results indicate that the combination of an organic homo‐rank compounds method and a homologous compounds method has exhibited obvious advantages over traditional methods in the quantitative structure–property relationship study of mono‐substituted alkanes concerning various substituents. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
79.
Cover Picture: Ruthenium‐Immobilized Periodic Mesoporous Organosilica: Synthesis,Characterization, and Catalytic Application for Selective Oxidation of Alkanes (Chem. Eur. J. 44/2015)
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80.
Propane σ‐Complexes on PdO(101): Spectroscopic Evidence of the Selective Coordination and Activation of Primary CH Bonds
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Feng Zhang Li Pan Juhee Choi Vikram Mehar John T. Diulus Prof. Aravind Asthagiri Prof. Jason F. Weaver 《Angewandte Chemie (International ed. in English)》2015,54(47):13907-13911
Achieving selective C? H bond cleavage is critical for developing catalytic processes that transform small alkanes to value‐added products. The present study clarifies the molecular‐level origin for an exceptionally strong preference for propane to dissociate on the crystalline PdO(101) surface via primary C? H bond cleavage. Using reflection absorption infrared spectroscopy (RAIRS) and density functional theory (DFT) calculations, we show that adsorbed propane σ‐complexes preferentially adopt geometries on PdO(101) in which only primary C? H bonds datively interact with the surface Pd atoms at low propane coverages and are thus activated under typical catalytic reaction conditions. We show that a propane molecule achieves maximum stability on PdO(101) by adopting a bidentate geometry in which a H? Pd dative bond forms at each CH3 group. These results demonstrate that structural registry between the molecule and surface can strongly influence the selectivity of a metal oxide surface in activating alkane C? H bonds. 相似文献