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71.
Adriana Esparza-Ruiz Heinrich Nöth Rosalinda Contreras 《Journal of organometallic chemistry》2009,694(23):3814-2098
The syntheses and structural analyses of a series of boron heterocycles derived from 2-(1H-benzimidazol-2-yl)-phenylamine (1), 2-(1H-benzimidazol-2-yl)-phenol (2), 2-(1H-benzimidazol-2-yl)-benzenedisulfide (3), 2-[3-(1,1,1,3,-tetramethyl-butyl)-phenyl]-2H-benzotriazole (4), 2-[3,5-bis-(1-methyl-1-phenylethyl)-phenyl]-2H-benzotriazole (5) and (C6H5)2BOH or BF3·OEt2 are reported. The new boron compounds: diphenyl-[2-(1H-benzimidazol-2-yl-κN)-phenylamide-κN]-boron (6), diphenyl-[2-(1H-benzimidazol-2-yl-κN)-phenolate-κO]-boron (7), diphenyl-[2-(1H-benzimidazol-2-yl-κN)-benzenethiolate-κS]-boron (8), diphenyl-[2-(2H-benzotriazol-2-yl-κN)-4-(1,1,3,3-tetramethyl-butyl)-phenolate-κO]-boron (9), diphenyl-[2-(2H-benzotriazol-2-yl-κN)-4,6-(1-methyl-1-phenylethyl)-phenolate-κO]-boron (10), difluoro-[2-(1H-benzimidazol-2-yl-κN)-phenolate-κO]-boron (11), difluoro-[2-(2H-benzotriazol-2-yl-κN)-4-(1,1,3,3-tetramethylbutyl)-phenolate-κO]-boron (12) and difluoro-[2-(2H-benzotriazol-2-yl-κN)-4,6-(1-methyl-1-phenylethyl)-phenolate-κO]-boron (13) have four fused rings, with boron included in a six-membered ring and bound to N, O or S atoms and strongly coordinated by a nitrogen atom from the imidazole or triazole rings. Their structures are zwitterionic, with a negative charge on the boron and a delocalized positive charge on the ligand. Compounds 6-12 were studied by NMR, IR, mass spectrometry, and 6-10 and 12 by X-ray diffraction analyses. 相似文献
72.
Raúl Colorado‐Peralta Cristina A. Lpez‐Rocha Sonia A. Snchez‐Ruiz Rosalinda Contreras Angelina Flores‐Parra 《Heteroatom Chemistry》2011,22(1):59-71
The structure and reactivity of a series of new ethylaminedithiazinanes and bis‐diethylaminedithiazinanes synthesized from formaldehyde, NaSH, and N,N‐dimethyl‐ethylene‐diamine ( 1 ), N‐methyl‐ethylene‐diamine ( 2 ), and N‐ethyl‐ethylene‐diamine ( 3 ) are reported. Compound 1 afforded 2‐([1,3,5]‐dithiazinan‐5‐yl)‐ethylene‐N,N‐dimethyl‐amine ( 4 ). The reaction of 4 with dry CH2Cl2 gave N‐{2‐([1,3,5]dithiazinan‐5‐yl)‐ethylene}‐N‐chloromethyl‐N,N‐dimethyl‐ammonium chloride ( 5 ) in high yield, whereas in wet CH2Cl2 and DMSO provided a mixture of 5 with N‐{2‐([1,3,5]‐dithiazinan‐5‐yl)‐ethylene}‐N,N‐dimethyl‐ammonium hydrochloride ( 6 ).bis‐{2‐([1,3,5]‐Dithiazinan‐5‐yl)‐ethylene‐N‐alkyl‐amino}‐methylene‐disulfides ( 7 ) and ( 8 ) formed by two dithiazinanes linked through the chain (CH2)2 NRCH2 S S CH2 NR (CH2)2‐ ( 7 R = methyl, 8 R = ethyl) reacted with CH2Cl2 giving after neutralization of the hydrolysis products the ethylaminedithiazinanes with different pendant N‐groups [ (CH2)2NMeH2+( 9 ); (CH2)2NEtH2+ ( 10 ); (CH2)2NMeH ( 11 ); (CH2)2NEtH ( 12 ); (CH2)2NMeHBH3 ( 13 ) (CH2)2NEtHBH3 ( 14 ). (CH2)2NMe2BH3 ( 15 ), and (CH2)2NEtMeBH3.( 16 )]. The x‐ray diffraction analyses of compounds 5 , 6 , 9 , and 10 are reported. Variable temperature NMR experiments afforded the Δ G≠ of the ring interconversion of the six‐membered heterocycles 6 , 9 , and 10 . © 2010 Wiley Periodicals, Inc. Heteroatom Chem 22:59–71, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20657 相似文献
73.
Bonilla JB Cid MB Contreras FX Goñi FM Martín-Lomas M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(5):1513-1528
The nature of chiro-inositol-containing inositolphosphoglycans (IPGs), reported to be putative insulin mediators, was studied by examination of the substrate specificities of the phosphatidylinositol-specific phospholipase C (PI-PLC) and the glycosylphosphatidylinositol-specific phospholipase D (GPI-PLD) by using a series of synthetic D- and L-chiro-glycosylphosphoinositides. 3-O-alpha-D-Glucosaminyl- (3) and -galactosaminyl-2-phosphatidyl-L-chiro-inositol (4), which show the maximum stereochemical similarity to the 6-O-alpha-D-glucosaminylphosphatidylinositol pseudodisaccharide motifs of GPI anchors, were synthesized and asymmetrically incorporated into phospholipid bilayers in the form of large unilamellar vesicles (LUVs). Similarly, 2-O-alpha-D-glucosaminyl- (5) and -galactosaminyl-1-phosphatidyl-D-chiro-inositol (6), which differ from the corresponding pseudodisaccharide motif of the GPI anchors only in the axial orientation of the phosphatidyl moiety, were also synthesized and asymmetrically inserted into LUVs. The cleavage of these synthetic molecules in the liposomal constructs by PI-PLC from Bacillus cereus and by GPI-PLD from bovine serum was studied with the use of 6-O-alpha-D-glucosaminylphosphatidylinositol (7) and the conserved GPI anchor structure (8) as positive controls. Although PI-PLC cleaved 3 and 4 with about the same efficiency as 7 and 8, this enzyme did not accept 5 or 6. GPI-PLD accepted both the L-chiro- (3 and 4) and the D-chiro- (5 and 6) glycosylinositolphosphoinositides. Therefore, IPGs containing L-chiro-inositol only are expected to be released from chiro-inositol-containing GPIs if the cleavage is effected by a PI-PLC, whereas GPI-PLD cleavage could result in both L-chiro- and D-chiro-inositol-containing IPGs. 相似文献
74.
Arráez-Román D Cortacero-Ramírez S Segura-Carretero A Martín-Lagos Contreras JA Fernández-Gutiérrez A 《Electrophoresis》2006,27(11):2197-2207
Hops are used almost exclusively for bitterness and flavor by brewers. We propose the first analytical application of CZE coupled to ESI-MS for the separation and structural elucidation of organic compounds in the methanolic extracts of hops, and different extraction procedures of the plant material have been carried out. The proposed method permits the identification of hop polyphenols (flavonoids glycosides and chalcones), bitter acids (alpha-acids and beta-acids), and their oxidation products. The optimization of CZE parameters (pH, concentration, and type of buffer) and ESI-MS parameters (nature and flow rate of the sheath liquid, nebulizer pressure, drying gas flow rate, temperature, and compound stability) have permitted the development of a rapid, simple, direct, and straightforward CZE-ESI-MS method for the identification of components of methanolic extracts from different hops used in the brewing process. 相似文献
75.
Ángel Rincón Ernesto Contreras Pedro Bargueño Benjamin Koch Grigorios Panotopoulos Alejandro Hernández-Arboleda 《The European Physical Journal C - Particles and Fields》2017,77(7):494
In the present work we study the scale dependence at the level of the effective action of charged black holes in Einstein–Maxwell as well as in Einstein–power-Maxwell theories in \((2+1)\)-dimensional spacetimes without a cosmological constant. We allow for scale dependence of the gravitational and electromagnetic couplings, and we solve the corresponding generalized field equations imposing the null energy condition. Certain properties, such as horizon structure and thermodynamics, are discussed in detail. 相似文献
76.
Julien Dugal‐Tessier Spencer C. Serin Emmanuel B. Castillo‐Contreras Dr. Eamonn D. Conrad Prof. Dr. Gregory R. Dake Prof. Dr. Derek P. Gates 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(20):6349-6359
The design of a synthetic route to a class of enantiomerically pure phosphaalkene–oxazolines (PhAk‐Ox) is presented. The condensation of a lithium silylphosphide and a ketone (the phospha‐Peterson reaction) was used as the P?C bond‐forming step. Attempted condensation of PhC(?O)Ox (Ox=CNOCH(iPr)C H2) and MesP(SiMe3)Li gave the unusual heterocycle (MesP)2C(Ph)?CN‐(S)‐CH(iPr)CH2O ( 3 ). However, PhAk‐Ox (S,E)‐MesP?C(Ph)CMe2Ox ( 1 a ) was successfully prepared by treating MesP(SiMe3)Li with PhC(?O)CMe2Ox (52 %). To demonstrate the modularity and tunability of the phospha‐Peterson synthesis several other phosphaalkene–oxazolines were prepared in an analogous manner to 1 a : TripP?C(Ph)CMe2Ox ( 1 b ; Trip=2,4,6‐triisopropylphenyl), 2‐iPrC6H4P?C(Ph)CMe2Ox ( 1 c ), 2‐tBuC6H4P?C(Ph)CMe2Ox ( 1 d ), MesP?C(4‐MeOC6H4)CMe2Ox ( 1 e ), MesP?C(Ph)C(CH2)4Ox ( 1 f ), and MesP?C(3,5‐(CF3)2C6H3)C(CH2)4Ox ( 1 g ). To evaluate the PhAk‐Ox compounds as prospective precursors to chiral phosphine polymers, monomer 1 a and styrene were subjected to radical‐initiated copolymerization conditions to afford [{MesPC(Ph)(CMe2Ox)}x{CH2CHPh}y]n ( 9 a : x=0.13n, y=0.87n; GPC: Mw=7400 g mol?1, PDI=1.15). 相似文献
77.
78.
Jorge Yañez María Paz Farías Valeria Zúñiga César Soto David Contreras Eduardo Pereira Héctor D. Mansilla Renato Saavedra Rosario Castillo Pedro Sáez 《Microchemical Journal》2012
Conventionally, chemical patterns of gunshot residues (GSR) can be used for identification of a suspect involved in criminal fire arm incidents. Furthermore, metals composition in GSR is well related with the ammunition brand. In Chile the two main ammunition brands used are FAMAE and CBC. Metals, such as Pb, Ba, Sb, Cu, Zn and Ca are common elements detected in both brands. This work describes the application of both conventional and chemometric analysis of data (Regularized Discriminant Analysis, RDA) for differentiation of ammunition brands according to the metal patterns of GSR collected from shooter individuals. Real samples of GSR were collected from hands (dorsal region) of both shooters and non-shooters. Metals were analyzed using the techniques Atomic Absorption Spectrometry (AAS) and Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-OES). By means of conventional plotting techniques for differentiation, such as binary and ternary plots, differences between the two brands are observed although without quantitative certainty. For the first time, applying chemometric analysis, such as regularized discriminant analysis (RDA), the investigated ammunition brands can be classified and differentiated correctly with 100% certainty. 相似文献
79.
Gonzalez-Suarez M Aizman A Soto-Delgado J Contreras R 《The Journal of organic chemistry》2012,77(1):90-95
The bond Fukui function is introduced and tested as a new reactivity index capable of predicting the evolution of bond breaking and formation processes during an organic reaction involving π conjugated systems. As an illustration, we examine many cases where substituted ethylenes and dienes may respond to different reagents to yield cycloaddition, Michael addition, and other reactions at double bonds. 相似文献
80.
Ricardo R. Contreras Bernardo Fontal Marisela Reyes Trino Surez Fernndo Bellandi All Bahsas 《Journal of heterocyclic chemistry》2001,38(5):1223-1225
The new compound Methyl‐2,4‐bis(cyclohexane)dispiro‐1,2,3,4,4a,5,6,7‐octahydro‐(1H,3H)‐quinazo‐line‐8‐carbodithioate has been synthesized from cyclohexanone and carbon disulfide. It has been characterized by uv‐visible, FTTR , mass spectra and a complete structure proposed based on 1H and 13C NMR spectroscopy. 相似文献