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111.
Zahra JA el-Abadelah MM Nazer MZ Ebraheem KA Boese R 《Organic & biomolecular chemistry》2003,1(10):1798-1801
The tautomerism of 4-methyldihydro-1,3,4-benzotriazepin-5-ones (2,3) is re-investigated by means of X-ray diffraction and quantum chemical calculations. The data revealed that the model compound (2a) exists in the amidrazone 1,4-dihydro tautomeric form (A), but not in the alternate 3,4-dihydro tautomer (B) as was previously reported. 相似文献
112.
N. S. Prostakov A. V. Varlamov V. P. Zvolinskii G. I. Cherenkova Butros Musa Butros Maria Elena Sintra 《Chemistry of Heterocyclic Compounds》1976,12(4):421-424
1,2 5-Trimethyl-4-(methyldiphenylsilyl)- and 4-(dimethylphenyl)silyl-4-piperidols were obtained. The isomers of these piperidols of the series, which exist in the chair conformation, have all of their substituents, except the hydroxyl group, equatorially oriented. The isomers of the series exist in solution in the form of an equilibrium mixture of chair and boat conformations, and all of the substituents, except the silyl grouping, are equatorially oriented in the chair conformation.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 502–505, April, 1976. 相似文献
113.
SOLVENT QUALITY AND SOLUTION BEHAVIOR OF NYLON 12 总被引:1,自引:0,他引:1
Musa Kaleem Baloch Munaza Qayum Mohsin Nawaz Sher Akber 《高分子科学》2007,(5):483-490
The refractive index increment,dynamic and static laser light scattering,intrinsic viscosity[η]and Huggins constant(K_H)of nylon 12 have been measured in m-cresol and sulphuric acid/water system at 10-60℃.The intrinsic viscosity,R_H,R_g,A_2,and(~2)~(1/2)(calculated from viscosity data)and"a"values of nylon 12 are found to be higher in m-cresol than in sulphuric acid.All these parameters decrease with the increase in water contents in sulphuric acid.The refractive index increment,K_H and activation energy show an opposite trend to that of[η].The intrinsic viscosity,R_H,R_g,A_2, and(~2)~(1/2) have maximum values around 30-40℃in sulphuric acid/water system,whereas in m-cresol they fall at about 20℃.It has been concluded that the variation in size,interaction parameter(second virial coefficient),[η]and K_H of the polymer solutions with the alteration in solvent composition and temperature are the out come of change in thermodynamic quality of solvents,selective adsorption,hydrogen bonding and conformational transitions.It has also been concluded that the increase in temperature first enhances the quality of the solvent,encourages hydrogen bonding and specific adsorption, and then deteriorates,bringing conformational transitions in the polymer molecules.However,the addition of water to sulphuric acid continuously deteriorates the solvent quality.This characteristic of the solvent system brings conformational changes in the polymer especially at low temperatures. 相似文献
114.
In this paper, a general idea of Presic type $L$-fuzzy fixed point results using some weakly contractive conditions in the setting of metric space is initiated. Stability of $L$-fuzzy mappings and associated new concepts are proposed herein to complement their corresponding notions related to crisp multi-valued and single-valued mappings. Illustrative nontrivial examples are provided to support the assertions of our main results. 相似文献
115.
116.
Mohammad Shakir Shama Parveen Nishat Begum Yasser Azim 《Transition Metal Chemistry》2004,29(8):916-920
A series of transition metal complexes of the type [M(ah)3](ClO4)2 (1–6) [M = MnII, FeII, CoII, NiII, CuII and ZnII, ah = acetylhydrazine] have been prepared by the reaction of M(ClO4)2 · 6H2O with acetylhydrazine formed in situ by the reaction of hydrazine hydrate and acetylsalicylic acid methyl ester. The chelating behaviour of acetylhydrazine and overall geometry of these complexes have been spectroscopically investigated by means of FT-IR, 1H-n.m.r. and electronic spectral techniques, as well as by elemental analysis data, molar conductance values and magnetic susceptibility measurements. Single X-ray structure determination of complex (4) revealed three acetylhydrazine ligands coordinated to nickel ion in a bidentate manner maintaining an octahedral environment. In all other complexes too, an octahedral geometry has been proposed on the basis of results obtained by various physico-chemical studies. 相似文献
117.
Musa Özil Fatih İslamoğlu Emre Menteşe Bahittin Kahveci 《Helvetica chimica acta》2010,93(10):1967-1974
The novel 4‐amino‐ or 4‐aryl‐substituted 2,4‐dihydro‐5‐[(4‐trifluoromethyl)phenyl]‐3H‐1,2,4‐triazol‐3‐ones 3a – 3g were synthesized by reaction of N‐(ethoxycarbonyl)‐4‐(trifluoromethyl)benzenehydrazonic acid ethyl ester ( 2 ) and primary amines or hydrazine by microwave irradiation. Compounds 3a – 3g were potentiometrically titrated with tetrabutylammonium hydroxide (Bu4NOH) in four nonaqueous solvents, i.e., iPrOH, tBuOH, MeCN, and N,N‐dimethylformamide (DMF). Also half‐neutralization potential values and the corresponding pKa values were determined in all cases. 相似文献
118.
Four new compounds of organic mono carboxylic acid, 3-maleimidopropionic acid; with Bu2Sn(IV)2+, Ph3Sn(IV)+ and Cychex3Sn(IV)+ having ligand to metal ratio 1:2 and 1:1 were prepared. The spectrophotometric techniques used for structure determination like 1H-, 13C- and 119Sn-NMR, FT IR and 119mSn Mössbauer have demonstrated that the organotin(IV) moieties establish chemical bonding with the ligand through carboxylic oxygen atom. The percent CHN analyses and MS data also corroborates the spectroscopic results. During in vitro LD50, anti-fungal, anti-bacterial and anti-yeast bioassays promising results were exhibited. In vitro anti-tumour activity assays against five human tumor cell lines, MCF-7 Breast cancer-EVSA-T Breast cancer-WiDr Colon cancer-IGROV Ovarian cancer-M226 Non small cell lung cancer and anti-inflammatory screenings furnished the significant toxicities of the title complexes. In addition the triorganotin(IV) complexes were comparatively less toxic than the diorganotin(IV) complexes. 相似文献
119.
120.
The intrinsic viscosity [η], Huggins constant (KH), laser light scattering, UV and IR measurements of Nylon 6 are made in m‐cresol and its mixture with 1,4‐dioxane at 20–60 °C. The intrinsic viscosity, Rg, A2, (<S>2)1/2 (calculated from viscosity data), RH, and UV absorbance initially increase and then decrease with the rise in 1,4‐dioxane contents. The KH and the transmittance of ? OH group in IR spectra show an opposite trend to that of [η]. The dielectric constant calculated from the refractive index of the solvent (m‐cresol with 1,4‐dioxane) and polymer solution shows a continuous decrease with the amount of 1,4‐dioxane. Activation energy shows a minimum while linear expansion coefficient (α3) maximum with the addition of 1,4‐dioxane. Change in [η], KH, and other characteristics of the polymer solutions with alterations in solvent composition and temperature are the result of variation in the thermodynamic quality of the solvent, its selective adsorption, hydrogen bonding, and conformational transitions. It has been concluded that the addition of 1,4‐dioxane first enhances the quality of the solvent, encourages hydrogen bonding, and specific adsorption, and then deteriorates, bringing conformational transitions in the polymer molecules. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 534–541, 2005 相似文献