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91.
Monjit Chamua Jibonjyoti Buragohain A. Bharali 《International journal of quantum chemistry》2024,124(1):e27292
The topological indices are reported to be very useful in various QSPR studies as these indices can be utilized as a tool to predict the physicochemical properties of a diverse set of chemical compounds. The objective of this communication is twofold. First, to introduce some neighborhood degree sum-based topological indices and perform a comparative QSPR analysis of the indices with their corresponding degree-based topological indices to analyze the usefulness of the new indices. Second, to investigate isomer discrimination ability of the newly defined indices on the basis of degeneracy test. Neighborhood degree sum-based topological indices not only consider the degree of each atom in the molecule but also the degrees of its neighboring atoms. Moreover, these indices are expected to provide information about how connected and dense the neighborhoods of atoms are within the molecule. In this study, we observe that the proposed neighborhood degree sum-based topological indices exhibit better correlation with some physicochemical properties of Octane Isomers and 66 alkanes as compared to their corresponding degree-based topological indices. Also, the supremacy in terms of sensitivity of the neighbourhood degree sum-based topological indices as compared to the classical degree-based ones is established. 相似文献
92.
Guilherme Tsuguio Tanaka Fabrício de Oliveira Ferreira Carlos Eduardo Ferreira da Silva Danilo Luiz Flumignan Jos Eduardo de Oliveira 《Journal of Chemometrics》2011,25(9):487-495
Samples of commercial gasoline, from the National Program of Fuel Quality Monitoring of the National Petroleum Agency, were collected from gas stations located in the Midwestern state of Sao Paulo, Brazil, and analyzed by several physicochemical standard methods established by ANP Resolution no. 309. Also, important information related to tampering was analyzed with the marker solvent. Statistical analysis and exploratory chemometric were employed to discriminate the presence of markers of solvents in commercial gasoline. The results showed that statistical and chemometric parameters such as atmospheric distillation temperatures T10 and T90, RON, benzene and saturated and aromatic hydrocarbons satisfactorily describe the presence of marker solvent, usually with a probability exceeding 70%. Furthermore, after optimizing the SIMCA algorithm, sensitivity in the training set with cross‐validation leave‐one‐out (83.8%) and the set of prediction (77.1%) were revealed. The proposed method will become indispensable and recommended for discriminating samples of fuels for commercial applications in routine monitoring programs and quality control. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
93.
An enhancement of environmental concern lately has improved the awareness of researchers in employing eco-friendly solvents for processing biopolymers. Recently, ionic liquids have been utilized to prepare biopolymer blends as they are non-volatile and recyclable. Biopolymers such as cellulose, chitin, chitosan, keratin, lignin, silk, starch, and zein are widely used for the preparation of biopolymer blends via dissolution in ionic liquids, followed by coagulation procedure. In this concise review, three types of ionic liquids based on imidazolium cations combined with different counter anions that are frequently utilized to prepare biopolymer blends are described. Moreover, three types of biopolymer blends that are prepared in ionic liquids were classified, specifically polysaccharide/polysaccharide blends, polysaccharide/polypeptide blends, and polysaccharide/bioplastic blends. The physicochemical properties of biopolymer blends prepared in different imidazolium-based ionic liquids are also concisely reviewed. This paper may assist the researchers in the polymer blend area and generate fresh ideas for future research. 相似文献
94.
95.
通过各种理化性质的测定,对不同提取方法所得褐藻糖胶进行了分析,乙醇沉淀法的测定结果为:总糖含量(76.00±9.00)%、硫酸根含量(11.33±0.47)%、岩藻糖含量(35.60±4.20)%、重均/数均分子量(3.42×104)/(1.21×104);高分子电解质沉淀法的测定结果为:总糖含量(70.00±11.00)%、硫酸根含量(10.80±0.58)%、岩藻糖含量(35.15±2.85)%、重均/数均分子量(1.15×105)/(5.88×104)。高分子电解质沉淀法所得褐藻糖胶粗品和纯化后褐藻糖胶,其高分子电解质残留量分别为(0.12±0.038)%和(0.022±0.002)%。结果表明,乙醇沉淀法所得产品质量优于高分子电解质沉淀法,但是高分子电解质沉淀法具有工艺简单、成本低,更适于工业化生产等优点。 相似文献
96.
97.
制备不同活性金属原子比的体相催化剂,通过BET、XRD、SEM、TEM、强度测定、堆积密度测定及小型活性评价手段,考察了活性金属钨、钼、镍含量的变化对体相催化剂物化性质和活性的影响。结果表明,保持W/Mo原子比不变,随着(W+Mo)/Ni的原子比减小,孔体积、比表面积、孔径增大,超深度加氢脱硫活性增强,在精制油硫含量小于10μg/g,反应温度降低8℃。在(W+Mo)/Ni的原子比不变的条件下,W/Mo的原子比在0.28-1.85,随着原子比增大,孔体积、比表面积、超深度加氢脱硫活性没有明显变化。 相似文献
98.
99.
Acoustical and viscosity measurements have been made for binary liquid mixtures of commercially available solvent extractants, LIX reagents such as LIX 622 and LIX 860 in benzene, amyl alcohol, and tri-n-butyl phosphate (TBP) at 303.15 K. The measured values of ultrasonic velocity, density, and viscosity have been utilized to compute some acoustic as well as thermodynamic parameters such as intermolecular free length, L
f, isentropic compressibility, s, molar volume, V, and Gibb's excess free energies of activation of viscous flow, G*E. These parameters along with the derived values of isentropic compressibility, s
E, intermolecular free length, L
f
E, and molar volume, V
E, have been utilized for a comparative study of molecular interactions between the components present in different liquid systems. The experimental ultrasonic velocities for aforementioned mixtures have been compared with theoretically estimated velocities using different empirical relations, and the relative merits of these theories and relations have been discussed in terms of percentage variation. 相似文献
100.
Chernyavskii A. I. Kononova E. G. Buzin M. I. Chernyavskaya N. A. 《Russian Chemical Bulletin》2003,52(4):952-957
Heterofunctional polycondensation of ,-dichloropermethyloligosilanes Cl(Me2Si)
m
Cl (m = 2—6) with 1,5-dihydroxyhexamethyltrisiloxane was used to synthesize linear permethylpoly(silane-siloxanes) with the regular structure —[(SiMe2)
m
O(SiMe2O)3]
n
—, which are soluble, unlike polydimethylsilane, in common organic solvents. The use of Py instead of Et3N as an acceptor of HNl results in an increase in the yield, molecular weight, and characteristic viscosity of the copolymers. The molecular weight and viscosity characteristics, oxidative and thermal stabilities, and spectral properties of the synthesized copolymers were studied. The dependence of the oxidative and thermal stabilities of the synthesized copolymers on the number of the SiMe2 units in the oligosilane fragment of the main chain was established. 相似文献