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91.
The nonlocal surface plasmon spectrum in a quantizing magnetic field perpendicular to the surface has been found to have branches analogous to ‘Bernstein’ modes near multiples of the cyclotron frequency. The n=2 nonlocal surface ‘Bernstein’ mode is evaluated for low wavenumber, incorporating Landau quantization effects for degenerate and nondegenerate cases. 相似文献
92.
Kayed A. Abu Safieh Mustafa M. El‐Abadelah Musa H. Abu Zarga Salim S. Sabri Wolfgang Voelter Ccilia M. M
ssmer 《Journal of heterocyclic chemistry》2001,38(3):623-628
The synthesis of some new pyrazolo[3′,4′:6,7]azepino[5,4,3‐cd] indoles (10a‐c) was achieved via regios‐elective cyclization of the respective 3‐(4‐acylaminopyrazol‐5‐yl)indoles (9a‐c) under Bischler‐Napieralski reaction conditions. The latter compounds were obtained by acylation of the corresponding 3‐(4‐aminopyra‐zol‐5‐yl)indoles (8a,b) which, in turn, were prepared by reduction of the 3‐(4‐nitropyrazol‐5‐yl)indoles precursors (7a,b) . The latter synthons were accessible from the reaction of indolylzinc chlorides (5a,b) with 5‐chloro‐1,3‐dimethyl‐4‐nitropyrazole. Ms and nmr spectral data of 10a‐c are in agreement with the assigned azepino‐indole structure as determined for 10a by X‐ray crystal measurements which demonstrate that the azepine ring is almost completely planar with the indole and pyrazole rings. 相似文献
93.
Michael A. Tallon Yulia Rogan Bilal Marie Raymond Clark Osama M. Musa Ezat Khosravi 《Journal of polymer science. Part A, Polymer chemistry》2014,52(17):2477-2501
The physiochemical properties, comonomer sequencing, and regiospecificity of the linkages between monomeric units within homo/copolymers based on 5,6‐di‐substituted norbornene and 7‐oxanorbornene type monomers by ring‐opening metathesis polymerization are reported and correlated to their primary and secondary structural elements. In general, first‐generation Grubbs‐ I1 ruthenium catalyst generates polymers with high trans content that exhibits an extended secondary structure with exo,exo substituents, whereas second‐generation Grubbs‐ I2 catalyst produces polymers with high cis content that forms tight turns, resulting in a compact structure. Furthermore, I2 ‐produced polymers exhibit a high level of alternating cis–trans double bonds along their polymeric backbone. In stark contrast, both first‐ and second‐generation Grubbs catalysts display complete reversal in cis/trans selectivity when an oxygen atom is in position‐7 of the norbornene‐ring along with mono‐endo‐substitution in position‐5 or 6, and hence highlighting the importance of stereoelectronic complexation by the catalyst with the next incoming monomer for cis/trans selectivity. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2477–2501 相似文献
94.
Barakat E. Abu Irmaileh Musa H. Abu Zarga Firas Awwadi Salim F. Haddad 《Natural product research》2015,29(10):893-898
Inula graveolens is a poisonous annual plant of Mediterranean origin. The invasive nature of the plant suggests that it may possess phytotoxic activity. The aim of this study was to assess the ability of I. graveolens to inhibit the growth of different plants in Petri dish and to identify the main bioactive compounds. Bio-guided fractionation of the plant extracts led to the isolation of 2,3,11β,13-tetrahydroaromaticin (THA) and ilicic acid. Both compounds showed selective and significant phytotoxic activity at 25 ppm. Root length of barley, oat, millet, tuberous canary grass and lentils were significantly reduced by 25 ppm of THA, while the root of cauliflower, cress and radish were similarly reduced by ilicic acid at 25 ppm. The structure of each compound was elucidated by using NMR and HR-MS. X-ray crystallography of THA is reported for the first time to confirm the relative stereochemistry of the compound. 相似文献
95.
Synthesis of a new 1,2,3,4,5‐pentasubstituted cyclohexanol and determining its stereochemistry by NMR spectroscopy and quantum‐chemical calculations
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Ibrahim Mamedov Rza Abbasoglu Musa Bayramov Abel Maharramov 《Magnetic resonance in chemistry : MRC》2016,54(4):315-319
The presence of substituents in cyclohexane can influence to the ratio of conformers; for some cases, the boat form is preferable. The new six‐membered cyclohexanol derivative 2 has been obtained by the synthesis of (E)‐1‐(bromophenyl)‐3‐phenylpropen‐2‐one ( 1 ). The NMR and quantum‐chemical conformational analysis for the 2 have carried out, and its possible mechanism of formation was given. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
96.
Murat Erdemoğlu Musa Sarıkaya Mehmet Canbazoğlu 《Journal of Dispersion Science and Technology》2013,34(4):439-442
Leaching of celestite mineral, SrSO4, with sodium sulfide, Na2S, was investigated from the point of strontium carbonate, SrCO3, production. Experiments were carried out to explain the conversion mechanism of celestite to strontium disulfide, SrS2, in Na2S solution. Effects of stirring speed, particle size, and concentration of Na2S on conversion were studied at constant temperature and solid‐to‐liquid ratio. The results showed that the rate of conversion mainly depends on Na2S concentration. It was concluded that leaching of celestite in Na2S solution for conversion to SrS2 is possible but slow. 相似文献
97.
Musa Şahin Bahri Ülküseven 《Phosphorus, sulfur, and silicon and the related elements》2013,188(5):545-554
Abstract The template reactions of salicylidene-, 5-bromosalicylidene-, and 3,5-dichlorosalicylidene-S-R-thiosemicarbazone (R: propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, dodecyl) with 5-bromo- and 3,5-dichlorosalicylaldehyde in the presence of nickel(II) yielded N1,N4-diarylidene-S-alkyl-thiosemicarbazone chelates. The N2O2 type complexes were isolated as stable solid compounds and characterized by elemental analysis, electronic, infrared, 1H NMR, and mass spectroscopies. The magnetic susceptibility measurements at room temperature (r.t.) indicate the diamagnetic nature of the complexes. The relationship between melting point (mp) values of the nickel(II) template complexes and the chain length of alkyl moiety was clearly shown. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the related elements to view the free supplemental file. 相似文献
98.
Huseyin Bekir Yildiz Dilek Odaci Demirkol Serkan Sayin Mustafa Yilmaz Ozcan Koysuren Musa Kamaci 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(10):1075-1084
Accumulation of cholesterol in human blood can cause several health problems such as heart disease, coronary artery disease, arteriosclerosis, hypertension, cerebral thrombosis, etc. Therefore, simple and fast cholesterol determination in blood is clinically important. In this study, two types of amperometric cholesterol biosensors were designed by physically entrapping cholesterol oxidase in conducting polymers; thiophene capped poly(ethyleneoxide)/polypyrrole (PEO-co-PPy) and 3-methylthienyl methacrylate-co-p-vinyl benzyloxy poly(ethyleneoxide)/polypyrrole (CP-co-PPy). PEO-co-PPy and CP-co-PPy were synthesized electrochemically and cholesterol oxidase was immobilized by entrapment during electropolymerization. The amperometric responses of the enzyme electrodes were measured by monitoring oxidation current of H2O2 at +0.7 V in the absence of a mediator. Kinetic parameters, such as Km and Imax, operational and storage stabilities, effects of pH and temperature were determined for both entrapment supports. Km values were found as 1.47 and 5.16 mM for PEO-co-PPy and CP-co-PPy enzyme electrodes, respectively. By using these Km values, it can be observed that ChOx immobilized in PEO-co-PPy shows higher affinity towards the substrate. 相似文献
99.
Musa I. El-Barghouthi Hamzeh M. Abdel-Halim Feryal J. Haj-Ibrahim Khaleel I. Assaf 《Supramolecular chemistry》2013,25(1-2):80-89
Molecular dynamics (MD) simulations were performed for cucurbit[6]uril (CB6) methyl and cyclohexyl derivatives in aqueous solutions. Furthermore, MD simulations have been conducted to study the inclusion complexes between each CB6 derivative with α,ω-pentane diammonium ion (NH3+(CH2)5NH3+) to estimate the binding free energies, the complex geometries and the intermolecular forces responsible for complex formation. Results show a complete inclusion of the guest molecule in the cavity of the host for all complexes. Results also indicate that the guest dynamics inside the cavity of the substituted host is similar to that for the unsubstituted host. This demonstrates that the molecular recognition of the host is not affected by the alkyl substitution at the equator. Also, there is an insignificant conformational change of the macrocyclic structure upon inclusion of the guest. Molecular mechanics/Poisson Boltzmann surface area method was used to estimate the binding free energy of each complex. Results indicate that host–guest electrostatic interactions make the largest contribution to the complex binding free energy. Moreover, van der Waals interactions add significantly to the complex stability. The guest molecules show more or less similar binding free energies with the substituted CB6 that exhibits slightly more negative values than unsubstituted CB6 which is proved also by umbrella sampling. 相似文献
100.
This study investigated the capacity of fast-scan (400 °C min?1) against conventional (10 °C min?1) differential scanning calorimetry (DSC) techniques to track crystallization phenomenon in tolbutamide–polyethylene glycol 3000 composites prepared by hot melt method (mass ratios 1:1, 1:5, and 1:9) and stored at 25 and 75 % relative humidities. Drug crystallization in composites was indicated by X-ray diffractometry (XRD) and scanning electron microscopy characterization over 40 days storage. With reference to XRD as gold measurement standard, fast-scan DSC could not map the crystallization events of composites (Pearson correlation: fast-scan DSC peak temperature and enthalpy versus XRD peak intensity and area, p > 0.05). Conventional DSC was able to indicate marked drug crystallization through an increase in endothermic enthalpy value of peaks at high temperature regimes between 250 and 360 °C due to formation of high melting point crystal form. 相似文献