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281.
Vivekanandan K Swamy MG Prasad S Mukherjee R 《Rapid communications in mass spectrometry : RCM》2005,19(21):3025-3030
To detect sub-ppb levels of the antibiotic chloramphenicol in honey matrix, a convenient method of extraction and measurement using liquid chromatography with detection by tandem mass spectrometry (LC/MS/MS) was developed. Honey samples fortified with chloramphenicol and isotopically labeled chloramphenicol were extracted using diatomaceous-based supported liquid-liquid extraction cartridges to generate a standard calibration curve. Four MS/MS transitions were used for quantification and four other transitions for confirmation of chloramphenicol. The limit of detection for chloramphenicol was 0.05 ng/g and the lower limit of quantification was 0.1 ng/g. Several commercial honey samples were analyzed for chloramphenicol content using this method. 相似文献
282.
A new fluorescein derivative has been synthesized for the detection of pyrophosphate (PPi) and ATP in 100% aqueous solution. Chemosensor 1 in the presence of Mn2+ (2.5 equiv) displayed selective fluorescent enhancements with PPi and ATP at pH 7.4. among the anions examined. The association constant of 1 in the presence of Mn2+ with PPi and ATP was calculated as 4.2 × 104 and 3.5 × 104 M−1. 相似文献
283.
A new fluorescent chemosensor based on the acridine-Zn(II) derivative effectively recognizes pyrophosphate and inorganic phosphate at pH 7.4. Acridine derivative 1 displayed a fluorescent quenching effect with pyrophosphate; on the other hand, a large fluorescent enhancement was observed with inorganic phosphate. [structure: see text]. 相似文献
284.
The title compound [In(C22H30N4O4)]Cl (I) bis[(N-salicylidene-N′-(2-hydroxyethyl)ethyleneediamine) indium(III) chloride is prepared, and its crystal structure is determined by single crystal X-ray diffraction at room temperature. The complex crystallizes in the monoclinic space group P21/n, a = 9.9704(6) ?, b = 24.9554(15) ?, c = 10.5707(6) ?, β = 116.46(2)°, V = 2354.6(2), Z = 4. The X-ray analysis reveals that the InIII ion is surrounded by four nitrogen and two oxygen atoms from two ligands leading to a distorted octahedral geometry. The molecule has the form of tongs at a junction point with the metal. Five membered rings adopt envelope conformation. In the crystal structure, the molecules are linked via N-H...Cl, O-H...O, O-H...Cl, and C-H...Cl intermolecular interactions. The structure is further stabilized by C-H...π (arene) interactions. 相似文献
285.
Kommana P Satish Kumar N Vittal JJ Jayasree EG Jemmis ED Kumara Swamy KC 《Organic letters》2004,6(2):145-148
[structure: see text] The sterically bulky tert-butyl group occupies an apical position in trigonal bipyramidal phosphorus in the compound [CH2(6-t-Bu-4-Me-C6H2O)2]P(t-Bu)(1,2-O2C6Cl4) in contrast to the occupation of an equatorial position by the small methyl group in [CH2(6-t-Bu-4-Me-C6H2O)2]P(Me)(1,2-O2C6Cl4); this observation contradicts the familiar "apicophilicity rules" for trigonal bipyramidal phosphorus. Low-temperature solution 31P NMR spectra of [CH2(6-t-Bu-4-Me-C6H2O)2]P(R)(1,2-O2C6Cl4) (R = Me, Et, and n-Bu) show the presence of more than two isomers. 相似文献
286.
Reaction of zirconium tetrakis(tert-butoxide) (1) with dicylohexylphosphinic acid in toluene leads to the dinuclear compound [Zr(mu,mu'-O(2)P(cycl-C(6)H(11))(2))(O-t-Bu)(3)](2) (2) in which the zirconium is pentacoordinated. An analogous reaction using diphenylphosphinic acid in tetrahydrofuran also leads to a dinuclear complex [Zr(mu,mu'-O(2)PPh(2))(THF)((O-t-Bu)(3)](2).C(6)H(5)CH(3) (3.C(6)H(5)CH(3)), in which zirconium is hexacoordinated. A novel exchange of tert-butoxy and phenoxy groups occurs when 1 is treated with diphenyl phosphate [(PhO)(2)PO(2)H] leading to the isolation of the exchange product [Zr(mu,mu'-O(2)P(O-t-Bu)(OPh))(mu-OPh)(O-t-Bu)(2)](2) (4). In contrast to the above, trinuclear zirconium compounds Zr(3(mu,mu'-O(2)AsMe(2))(2)(mu2,mu'-O(2)AsMe(2))(O-t-Bu)(7)(mu-O-t-Bu)(2) (5) and Zr(3(mu,mu'-O(2)P(O-t-Bu)(2))(5)(O-t-Bu)(7).(1)/(2)C(6)H(5)CH(3) (6.(1)/(2)C(6)H(5)CH(3)) have been isolated from the reaction of 1 with cacodylic acid and di-tert-butyl phosphate, respectively. The X-ray structures of 2, 3, 5, and 6 have been determined; although the X-ray structural analysis of 4 could not be satisfactorily finished, it reveals the disposition of the substituents. The solution state NMR data suggest that these compounds undergo structural changes in solution. Possible relationships among the various structures are discussed. 相似文献
287.
The compound [C12H17N2]3[Bi2Cl9]·2EtOH (1) has been synthesized from bismuth trichloride and o-phenylenediamine (opda) in ethanol at an aerial ambient condition. This preparation includes the conversion of opda to 2,3-dihydro-1H-1,5-benzodiazepinium cation through its reaction with acetone that is formed in situ from aerial ethanol oxidation. Compound 1 crystallizes in triclinic system (space group P−1). In the crystal structure of 1, the supramolecular hydrogen bonding interactions between [Bi2C9]3− and [C12H17N2]+ play an important role in the stabilization of cationic form of 2,3-dihydro-1H-1,5-benzodiazepine and in obtaining emission signals of the organic moiety, which is otherwise not emissive. Compound [C12H17N2]3[Bi2Cl9]·2(2-PrOH) (2), that has been isolated from 2-propanol (instead of ethanol), is isostructural with compound 1. 相似文献
288.
289.
[reaction: see text] We herein report a new synthesis of 2-(hetero)aryl-substituted pyridines via heteroarylation of arenes/heteroarenes through AlCl(3)-induced C-C bond-forming reactions. 2-Halopyridines bearing an electron-withdrawing group were reacted with a number of (hetero)arenes to give 2-aryl/heteroaryl-substituted pyridines in good yields. 相似文献
290.