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261.
The reactions taking place in the mixed solution of biphenyl and nitrous acid after it was exposed to UV irradiation were studied in this research work. The transient species were identified with the nanosecond transient spectroscopic technique, and the final products were ascertained by GC-MS analysis. It was shown that the OH radical, generated by the direct photolysis of nitrous acid, would attack biphenyl molecule to form Bp-OH adduct with a rate constant of 9.5×109 L·mol-1·s-1. The Bp-OH adduct could either react with H or be oxidized by nitrous acid to form nitrosobiphenol. The reactions between biphenyl and nitrous acid under UV irradiation in atmospheric aqueous phase were therefore suggested to be one promising source of nitrocompounds in the environment. 相似文献
262.
263.
The dimeric and centrosymmetric structure of [Zn(S2CNEt2)2(trans‐NC5H4C(H)?C(H)C5H4N)]2 shows bidentate coordination by the dithiocarbamate ligands and a distorted square pyramidal geometry for zinc, defined by a NS4 donor set with the N atom in the apical position. The compound co‐crystallises with a centrosymmetric molecule of trans‐NC5H4C(H)?C(H)C5H4N that does not form a significant interaction to the Zn atom. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
264.
An acid-promoted intramolecular Friedel-Crafts reaction of the Morita-Baylis-Hillman adducts 3 derived from 2-arylthioquinolin-3-carbaldehydes 2 was investigated. Interestingly, promoted by sulfuric acid, the substrates with electron-donating groups on the aromatic ring gave six-membered fused-ring 12H-thiochromeno[2,3-b]quinolines 4 with good yields, while those with electron-withdrawing groups afforded eight-membered fused-ring 5H-benzo[7,8]thiocino[2,3-b]quinolines 5 in moderate yields. Using triflic acid instead of sulfuric acid, only products 4 could be obtained under the similar condition. 相似文献
265.
13C NMR chemical shift assignments were obtained for the Diels-Alder adduct of phencyclone with norbornadiene in CD2Cl2 and in CDCl3 solution. The 13C spectrum at 50.3 MHz, as well as the 1H spectrum at 200.1 MHz, show evidence for hindered rotation of the two unsubstituted bridgehead phenyl rings of the adduct at ambient temperatures. In CD2Cl2 solution, all 19 of the unique 13C nuclei of this molecule give rise to individual 13C resonances. The 1H assignments which were made earlier, together with one-bond and long-range 2D heteronuclear correlation experiments, allowed the assignment of all 13C chemical shifts in the molecule. 相似文献
266.
267.
Three Lewis acid–base adducts t‐Bu3Ga–EPh3 (E = P 1 , As 2 , Sb 3 ) were synthesized by reactions of Ph3E and t‐Bu3Ga and characterized by heteronuclear NMR (1H, 13C (31P)) and IR spectroscopy, elemental analysis and single crystal X‐ray diffraction. Their structural parameters are discussed and compared to similar t‐Bu3Ga adducts. The strength of the donor‐acceptor interactions within 1 – 3 was investigated in solution by temperature‐dependent 1H NMR spectroscopy and by quantum chemical calculations. 相似文献
268.
Raju Venkata Veera Tatituri Michael B. Brenner John Turk Fong‐Fu Hsu 《Journal of mass spectrometry : JMS》2012,47(1):115-123
The cell wall of the pathogenic bacterium Streptococcus pneumoniae contains glucopyranosyl diacylglycerol (GlcDAG) and galactoglucopyranosyldiacylglycerol (GalGlcDAG). The specific GlcDAG consisting of vaccenic acid substituent at sn‐2 was recently identified as another glycolipid antigen family recognized by invariant natural killer T‐cells. Here, we describe a linear ion‐trap multiple‐stage (MSn) mass spectrometric approach towards structural analysis of GalGlcDAG and GlcDAG. Structural information derived from MSn (n = 2, 3) on the [M + Li]+ adduct ions desorbed by electrospray ionization affords identification of the fatty acid substituents, assignment of the fatty acyl groups on the glycerol backbone, as well as the location of double bond along the fatty acyl chain. The identification of the fatty acyl groups and determination of their regio‐specificity were confirmed by MSn (n = 2, 3) on the [M + NH4]+ ions. We establish the structures of GalGlcDAG and GlcDAG isolated from S. pneumoniae, in which the major species consists of a 16:1‐ or 18:1‐fatty acid substituent mainly at sn‐2, and the double bond of the fatty acid is located at ω‐7 (n‐7). More than one isomers were found for each mass in the family. This mass spectrometric approach provides a simple method to achieve structure identification of this important lipid family that would be very difficult to define using the traditional method. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
269.
Three half-sandwichruthenium(II) complexes with pyridine/phenylene bridged NHC = E (NHC = N-heterocyclic carbene, E = S, Se) ligands [Ru(p-cymene)L](PF6)1–2 ( 1a–1c , L = ligand) were synthesized and characterized. All ruthenium complexes were fully characterized by 1H and 13C NMR spectra, mass spectrometry, and single-crystalX-ray diffraction methods. Moreover, the half-sandwich ruthenium complexes with NHC = E ligands showed highly catalytic activities towards to the tandem dehydrogenation of ammonia borane (AB) and hydrogenation of R–NO2 to R–NH2 at 353 K in water. 相似文献
270.