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91.
In an earlier attempt to solve problems of Fluid-Structure Interaction (FSI), a high-order finite element code, which can be applied to solve problems of Computational Structural Dynamics (CSD) has been coupled to a Lattice Boltzmann (LB) fluid solver. In order to extend this approach to maritime applications and to increase the computational efficiency, the CSD solver is coupled to a fluid solver based on the Boundary Element Method (BEM). In this way, the computational effort for the discretisation of the fluid is significantly reduced. In this paper the proposed coupling scheme is discussed and compared to a FSI scheme where the BEM is replaced by a method based on the Reynolds-averaged Navier-Stokes equations (RANSE). Special emphasis is placed on the question of how to exchange the data between the different discretisation schemes and the development of a stable and efficient coupling scheme for FSI simulations. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
92.
Khalid A. Al-Farhan Ismail Warad Saud I. Al-Resayes Moustafa M. Fouda Mohamed Ghazzali 《Central European Journal of Chemistry》2010,8(5):1127-1133
Borneol is a monoterpene that is a part of traditional Chinese and Japanese medicine. (−) borneol reacted with methanesulfonyl
chloride in THF/pyridine to afford the new 1,7,7-trimethylbicyclo[2.2.1]hept-2-yl methane sulfonate derivative in excellent
yield. The product is characterized by H1NMR, C13NMR, mass spectroscopy as well as elemental analysis and its structure was identified by X-ray single crystal diffraction.
The packing of 1,7,7-trimethylbicyclo[2.2.1]hept-2-yl methanesulfonate exhibits the non-classical C-H···O hydrogen bonding
in C(4) and R2
2(8) chain and ring motifs as structural determinants. This was also confirmed by the analysis of Hirshfeld surfaces. The 1,7,7-trimethylbicyclo[2.2.1]hept-2-yl
methane sulfonate antimicrobial activity was tested and compared with its parent (−) borneol against three different pathogens.
Particularly, 1,7,7-trimethylbicyclo[2.2.1]hept-2-yl methane sulfonate showed high sensitivity, compared to Chloramphenicol
reference material, against Escherichia coli.
相似文献
93.
The proton transfer reactions between chromotropic acid (CTA) and some amines including benzylamine (BA), triethylamine (TEA), pyrrolidine (PY) and 1,8-bis(dimethylamino) naphthalene (DMAN) have been investigated spectrophotometrically in methanol. A long wavelength band at 365 nm has been recorded due to the proton transfer (PT) complex formation. The proton transfer equilibrium constants KPT were estimated utilizing the minimum–maximum absorbances method. It has been found that KPT were not depend on the amine pKa values, but strongly depend on the formed structures of the PT complexes. Job’s method of continuous variations and photometric titrations were applied to identify the compositions of the formed PT complexes where 1:1 complexes (proton donor: proton acceptor) were produced. Due to the rapidity and simplicity of the proton transfer reactions and the stability of the formed complexes, a rapid and accurate spectrophotometric method for the determination of CTA was proposed for the first time. 相似文献
94.
This paper presents the conductivity measurements for some alkaline earth metal salts MgCl2, MgBr2, Mg(NO3)2, CaCl2, CaBr2 and Ca(NO3)2 by which the ion-solvent interactions are reported in the concentration range in dioxane-water mixtures at mass fraction of 0, 3, 10, 20 and 30% at 30°, 35°, 40° and 45°C ± 0.01. The conductance data were analyzed for the limiting molar conductivity, Ao, by the Fuoss-Edelson conductivity equation for the 2:1 unsymmetrical electrolytes. The results were discussed in terms of the solute-solvent interaction from the temperature coefficient of Walden product, Λoη of the electrolyte solutions. Moreover, Λoη was found to exhibit a linear relationship with the dielectric constant, ?, of the dioxane-water mixtures. The study gives information regarding the ion-solvent interactions from the mobilities and Walden product of the ions in the solvent. The ions appear to interact appreciably and the ion-solvent interaction tends to increase in the order Ca > Mg for the same anion while for the anions, the trend decreases in the order Cl? < Br? < No?3. 相似文献
95.
The design and synthesis of two novel quinoxalinophenanthrophenazine-based anion sensors are reported. Binding studies of these sensors with an array of mono- and polyatomic anions using UV-vis, fluorescence, and NMR titrations have shown 1:1 and 1:2 sensor-to-anion ratios. Binding constants were calculated for anions, which exhibited high affinity for the sensors, including acetate, benzoate, cyanide, and fluoride ions. 相似文献
96.
A. S. Badran A. A. Abd-El-Hakim A. B. Moustafa M. A. Abd El-Ghaffar 《Journal of polymer science. Part A, Polymer chemistry》1988,26(2):609-614
The polymerization of methyl acrylate in water using ammonium, potassium, and sodium persulphates with sodium bisulphite as redox initiation system was studied. It has been found that ammonium persulphate had the least activity on the rate of polymerization and resulted in the formation of the highest viscosity average molecular weights for the obtained polymers. The rate of polymerization was found to increase with sodium bisulphite concentration in the redox system, but the viscosity average molecular weights were found to decrease with the increase of sodium bisulphite concentration. Addition of some inorganic silicon compounds (containing the same weight equivalent of SiO2) resulted in increasing the rate of polymerization and decreasing the induction period. The average molecular weights obtained in presence of china clay were found to be the highest and those obtained in presence of talc were the least. 相似文献
97.
Taha A. Hussien Tarik A. Mohamed Abdelsamed I. Elshamy Mahmoud F. Moustafa Hesham R. El-Seedi Paul W. Pare Mohamed-Elamir F. Hegazy 《Molecules (Basel, Switzerland)》2021,26(7)
Centaurothamnus maximus (family Asteraceae), is a leafy shrub indigenous to the southwestern Arabian Peninsula. With a paucity of phytochemical data on this species, we set out to chemically characterize the plant. From the aerial parts, two newly identified guaianolides were isolated: 3β-hydroxy-4α(acetoxy)-4β(hydroxymethyl)-8α-(4-hydroxy methacrylate)-1αH,5αH, 6αH-gual-10(14),11(13)-dien-6,12-olide (1) and 15-descarboxy picrolide A (2). Seven previously reported compounds were also isolated: 3β, 4α, 8α-trihydroxy-4-(hydroxymethyl)-lαH, 5αH, 6βH, 7αH-guai-10(14),11(13)-dien-6,12-olide (3), chlorohyssopifolin B (4), cynaropikrin (5), hydroxyjanerin (6), chlorojanerin (7), isorhamnetin (8), and quercetagetin-3,6-dimethyl ether-4’-O-β-d-pyranoglucoside (9). Chemical structures were elucidated using spectroscopic techniques, including High Resolution Fast Atom Bombardment Mass Spectrometry (HR-FAB-MS), 1D NMR; 1H, 13C NMR, Distortionless Enhancement by Polarization Transfer (DEPT), and 2D NMR (1H-1H COSY, HMQC, HMBC) analyses. In addition, a biosynthetic pathway for compounds 1–9 is proposed. The chemotaxonomic significance of the reported sesquiterpenoids and flavonoids considering reports from other Centaurea species is examined. 相似文献
98.
Ralf M. Peetz Ahmed F. Moustafa Joseph P. Kennedy 《Journal of polymer science. Part A, Polymer chemistry》2003,41(6):740-751
Two structurally closely related three‐arm star blocks were synthesized and characterized: tCum(PIB‐b‐PNBD)3 and tCum(PNBD‐b‐PIB)3 [where tCum (tricumyl) stands for the phenyl‐1,3,5‐tris(‐2‐propyl) fragment and PIB and PNBD are polyisobutylene and polynorbornadiene, respectively]. The syntheses were accomplished in two stages: (1) the preparation of the first (or inner) block fitted with appropriate chlorine termini capable of initiating the polymerization of the second (or outer) block with TiCl4 and (2) the mediation of the polymerization of the second block. Therefore, the synthesis of tCum(PIB‐b‐PNBD)3 was effected with tCum(PIB‐Clt)3 [where Clt is tert‐chlorine and number‐average molecular weight (Mn) = 102,000 g/mol] by the use of TiCl4 and 30/70 CH3Cl/CHCl3 solvent mixtures at ?35 °C. PNBD homopolymer contamination formed by chain transfer was removed by selective precipitation. According to gel permeation chromatography, the Mn's of the star blocks were 107,300–109,200 g/mol. NMR spectroscopy (750 MHz) was used to determine structures and molecular weights. Differential scanning calorimetry (DSC) indicated two glass‐transition temperatures (Tg's), one each for the PIB (?65 °C) and PNBD (232 °C) phases. Thermogravimetric analysis thermograms showed 5% weight losses at 293 °C in air and at 352 °C in N2. The synthesis of tCum(PNBD‐b‐PIB)3 was achieved by the initiation of isobutylene polymerization with tCum(PNBD‐Clsec)3 (where Clsec is sec‐chlorine and Mn = 2900 g/mol) by the use of TiCl4 in CH3Cl at ?60 °C. DSC for this star block (Mn = 14,200 g/mol) also showed two Tg's, that is, at ?67 and 228 °C for the PIB and PNBD segments, respectively. It is of interest that the Clsec terminus of PNBD, , readily initiated isobutylene polymerization. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 740–751, 2003 相似文献
99.
M. M. Moustafa 《Monatshefte für Chemie / Chemical Monthly》1995,126(3):255-261
Summary The chelates formed between 1,4-bis(2-hydroxyphenylazomethine) phenylene with La, Ce, Pr, Nd, Sm, Gd, Dy, Er, Yb, and Lu ions have been investigated in solution using conductometric, potentiometric, and spectrophotometric methods. The studies revealed the formation ofM
2
L andML complexes. The solid chelates have been characterized by elemental and thermal analysis, molar conductance, IR,1H NMR (for La and Lu chelates), and electronic spectra. The bonding takes place through the coordination of nitrogen in the -CH=N- group and the oxygen of the hydroxyl group by proton displacement.
Synthese und Charakterisierung einiger neuer Lanthanid(III)-Chelate mit 1,4-bis-(2-Hydroxyphenylazomethin)-phenylen
Zusammenfassung Chelate von 1,4-bis-(2-Hydroxyphenylazomethin)-phenylen mit La, Ce, Pr, Nd, Sm, Gd, Dy, Er, Yb und Lu in Lösung wurden konduktometrisch, potentiometrisch und spektrophotometrisch untersucht. Die Bildung von Komplexen der FormM 2 L undML wurde festgestellt. Die festen Chelate wurden mittels Elementaranalyse. Thermoanalyse, molarer Leitfähigkeit, IR-, UV/Vis-und im Fall von La und Lu-NMR-Spektroskopie charakterisiert. Die Komplexbindung erfolgt durch Koordination des Stickstoffs der -CH=N- Gruppe und des Sauerstoffs der Hydroxylgruppe unter Protonenverschiebung.相似文献
100.
A. Heshmat Moustafa Samia A. El-Abbady R. Alan Jones 《Journal of heterocyclic chemistry》1981,18(7):1461-1463
Cycloaddition to 1-(4,6-dimethylpyrimidin-2-yl)- and 1-(4,6-dimethoxy-s-triazin-2-yl)-3-oxidopyridinium betaines across the 2,6-positions of the pyridine rings with indene, acenaphthylene and ethyl cinnamate gave substituted 8-aza[3.2.1]bicycIooct-3-en-2-ones, whereas the [6π + 4π] cycloaddition reaction with 6,6-dimethylfulvene gave a tricyclo[6.3.1.02.6]dodeca-2,(6),4,9-trien-11-one. Structural and configurational assignments of the cycloadducts were deduced from 1H nmr and ir spectral data. 相似文献