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371.
Ahmad Aqel Kholoud M.M. Abou El-Nour Reda A.A. Ammar Abdulrahman Al-Warthan 《Arabian Journal of Chemistry》2012,5(1):1-23
Since their discovery in 1991 by the Japanese scientist “Sumio Iijima”, carbon nanotubes have been of great interest, both from a fundamental point of view and for future applications. Different types of carbon nanotubes can be produced in various ways. Economically feasible large-scale production and purification techniques are still under development. Carbon nanotubes are discussed in this review in terms of history, types, structure, synthesis and characterisation methods. Carbon nanotubes have attracted the fancy of many scientists worldwide. The unique and unusual properties of these structures make them a unique material with a whole range of promising applications. 相似文献
372.
Khaled Abou‐Hadeed Roland W. Kunz Anthony Linden Hans‐Jürgen Hansen 《Helvetica chimica acta》2012,95(6):885-921
Dimethyl heptalene‐4,5‐dicarboxylates 1 The locants of heptalene itself are maintained throughout the whole work. See footnote 4 in [1] for reasoning. undergo preferentially a Michael addition reaction at C(3) with α‐lithiated alkyl phenyl sulfones at temperatures below ?50°, leading to corresponding cis‐configured 3,4‐dihydroheptalene‐4,5‐dicarboxylates (cf. Table 1, Schemes 3 and 4). The corresponding heptalenofuran‐1‐one‐type pseudoesters of dimethyl heptalene‐4,5‐dicarboxylates (Scheme 5) react with [(phenylsulfonyl)methyl]lithium almost exclusively at C(1) of the furanone group (Scheme 6). In contrast to this expected behavior, the uptake of 1‐[phenylsulfonyl)ethyl]lithium occurs at C(5) of the heptalenofuran‐1‐ones as long as they carry a Me group at C(11) (Schemes 6 and 7). The 1,4‐ as well as the 1,6‐addition products eliminate, on treatment with MeONa/MeOH in THF, benzenesulfinate, thus leading to 3‐ and 4‐alkylated dimethyl heptalene‐4,5‐dicarboxylates, respectively (Schemes 8–13). The configuration of the addition reaction of the nucleophiles to the inherently chiral heptalenes is discussed in detail (cf. Schemes 14–19) on the basis of a number of X‐ray crystal‐structure determinations as well as by studies of the temperature‐dependence of the 1H‐NMR spectra of the addition products. 相似文献
373.
Farag M. A. Altalbawy Gehad G. Mohamed Mohsen Abou El-Ela Sayed Mohamed I. A. Mohamed 《Monatshefte für Chemie / Chemical Monthly》2012,18(1):79-89
Abstract
The coordination behaviour of a Schiff base with SNO donation sites, derived from condensation of 4-amino-5-phenyl-4H-1,2,4-triazole-3-thiol and salicaldehyde, towards some bi- and trivalent metal ions, namely Cr(III), Mn(II), Fe(III), Co(II) (Cl, ClO4), Ni(II) (Cl, ClO4), Cu(II), and Zn(II), is reported. The metal complexes were characterized on the basis of elemental analysis, IR, 1H NMR, solid reflectance, magnetic moment, molar conductance, and thermal analyses (TG, DTG, and DTA). The ionization constant of the Schiff base under investigation and the stability constants of its metal chelates were calculated pH-metrically at 25 °C and ionic strength μ = 0.1 M in 50% (v/v) ethanol–water mixture. The chelates were found to have octahedral (Mn(II)), trigonal bipyramidal (Co(II), Ni(II), Zn(II)), and tetrahedral (Cr(III), Fe(III), and Cu(II)) structures. The ligand and its binary chelates were subjected to thermal analyses and the different thermodynamic activation parameters were calculated from their corresponding DTG curves to throw more light on the nature of changes accompanying the thermal decomposition process of these compounds. The free Schiff base ligand and its metal complexes were tested in vitro against Aspergillus flavus, Candida albicans, C. tropicalis, and A. niger fungi and Bacillus subtilis and Escherichia coli bacteria in order to assess their antimicrobial potential. The results indicate that the ligand and its metal complexes possess antimicrobial properties. 相似文献374.
The reaction of 1,n-dichloroalkanes 3a (n=2-6) with an excess of lithium powder and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB; 2.5 mol %) in the presence of different carbonyl compounds [ButCHO, PhCHO, Et2CO, (CH2)4CO, (CH2)5CO, (CH2)7CO, (−)-menthone], in THF at −78 °C leads, after hydrolysis with water, to the expected 1,(n+2)-diols 4, yields being <25% for n=2, 3 and in the range of 45-79% for n=4-6. When the same protocol is applied to 1,n-bromochloroalkanes 3b and 1,n-dibromoalkanes 3c (n=2-6), diols 4 are obtained in general with lower yields. 相似文献
375.
El-Hamd H Mohamed A Ahmed AA Wollenweber E Bohm B Asakawa Y 《Chemical & pharmaceutical bulletin》2006,54(2):152-155
Investigation of lipophilic exudates from the aerial parts of Balsamorhiza sagittata and B. macrophylla afforded three new highly oxygenated guaianolides (1-3), in addition to known guaianolides, germacranolide and eudesmane acids. Their chemical structures were elucidated by spectroscopic methods and the data for the compounds are reported in Tables 1 and 2 and in Experimental. 相似文献
376.
Kamal A. Kandeel Ahmed S. A. Youssef Wael S. I. Abou‐Elmagd Ahmed I. Hashem 《Journal of heterocyclic chemistry》2006,43(4):957-962
377.
Sayed M. Abdallah Gehad G. Mohamed M.A. Zayed Mohsen S. Abou El-Ela 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,73(5):833-840
New Schiff base (H2L) ligand is prepared via condensation of o-phthaldehyde and 2-aminophenol. The metal complexes of Cr(III), Mn(II), Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with the ligand are prepared in good yield from the reaction of the ligand with the corresponding metal salts. They are characterized based on elemental analyses, IR, solid reflectance, magnetic moment, electron spin resonance (ESR), molar conductance, 1H NMR and thermal analysis (TGA). From the elemental analyses data, the complexes are proposed to have the general formulae [M(L)(H2O)n]·yH2O (where M = Mn(II) (n = 0, y = 1), Fe(II) (n = y = 0), Co(II) (n = 2, y = 0), Ni(II) (n = y = 2), Cu(II) (n = 0, y = 2) and Zn(II) (n = y = 0), and [MCl(L)(H2O)]·yH2O (where M = Cr(III) and Fe(III), y = 1–2). The molar conductance data reveal that all the metal chelates are non-electrolytes. IR spectra show that H2L is coordinated to the metal ions in a bi-negatively tetradentate manner with ONNO donor sites of the azomethine N and deprotonated phenolic-OH. This is supported by the 1H NMR and ESR data. From the magnetic and solid reflectance spectra, it is found that the geometrical structures of these complexes are octahedral (Cr(III), Fe(III), Co(II) and Ni(II) complexes), tetrahedral (Mn(II), Fe(II) and Zn(II) complexes) and square planar (Cu(II) complex). The thermal behaviour of these chelates is studied and the activation thermodynamic parameters, such as, E*, ΔH*, ΔS* and ΔG* are calculated from the DrTGA curves using Coats-Redfern method. The parent Schiff base and its eight metal complexes are assayed against two fungal and two bacterial species. With respect to antifungal activity, the parent Schiff base and four metal complexes inhibited the growth of the tested fungi at different rates. Ni(II) complex is the most inhibitory metal complex, followed by Cr(III) complex, parent Schiff base then Co(II) complex. With regard to bacteria, only two of the tested metal complexes (Mn(II) and Fe(II)) weakly inhibit the growth of the two tested bacteria. 相似文献
378.
Omer Nur Magnus Willander Muhammad Q. Israr Fawzy G. El Desouky Mohamed A. Salem Ali B. Abou Hamad Inas K. Battisha 《Physica B: Condensed Matter》2012,407(14):2697-2704
Nano-composite Ba1−xSr(x)TiO3 (BST), where x=0.01–0.50 and doped with different concentrations of iron Ba(1−x−y)Sr(x)TiFe (y)O3 (BSTF), where x=0.01 and y=0.01–0.05 powders were prepared by sol–gel method. 相似文献
379.
Alaa A. Hassan Aboul‐Fetouh E. Mourad Kamal M. El‐Shaieb Ashraf H. Abou‐Zied Dietrich Dpp 《Heteroatom Chemistry》2003,14(6):535-541
Microwave and thermal heterocyclization of N,N′‐disubstituted hydrazinecarbothioamide 1a,b and substituted thioureidoethylthioureas 2a–c as well as 1‐phenyl‐3[2‐(3‐phenylthio‐ureido)phenyl]thiourea 6 are reported. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:535–541, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10188 相似文献
380.