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41.
Benito Alcaide Gerardo Escobar Rafael Pérez-Ossorio Joaquin Plumet 《Journal of heterocyclic chemistry》1984,21(3):919-921
The carbonyl group of substituted 5-benzoyl-4,5-dihydro-1,2,4-oxadiazoles can be reduced by lithium aluminium hydride at low temperature without ring opening. Mixtures of the two related diastereoisomeric benzylalcohols are obtained. Configurations were assigned by 1H-nmr. 相似文献
42.
Recent advances in vibrational spectroscopy have greatly enhanced the possibilities of research of highly excited states in molecular systems of moderate size. At sufficiently high level of excitation the correspondence principle holds, and classical mechanical arguments constitute a useful interpretative tool. The corresponding dynamics often become very complex specially in systems with floppy degrees of freedom, and periodic motion plays an important role for its understanding. In this paper, we present a computational procedure to systematically calculate periodic orbits of LiNCLiCN with a given symmetry, that has the additional advantage of providing a useful insight into the onset of chaos in this system. 相似文献
43.
J. Fdez Ferreras C. Pesquera F. González I. Benito C. Blanco J. Renedo 《Reaction Kinetics and Catalysis Letters》1994,53(1):1-6
Nickel catalysts prepared using two different clays as support, natural bentonite and palygorskite, and with different nickel contents have been tested in the hydrogenation of a sunflower oil. The influence of the clays, and of the nickel-bentonite ratio on the activity, selectivity and trans-isomer formation was investigated. Previously it was establised that no diffusional limitations were controlling the rate. Bentonite with the highest nickel content was the most active and selective catalysts. 相似文献
44.
Sánchez-Méndez A Benito JM de Jesús E de la Mata FJ Flores JC Gómez R Gómez-Sal P 《Dalton transactions (Cambridge, England : 2003)》2006,(45):5379-5389
The substituted bis(pyrazolyl)methane ligands RCH(3,5-Me2pz)2(R=SiMe3, CH2Ph, G1, G2, and G3; Gn=Fréchet-type dendritic wedges of generation n) have been prepared starting from H2C(3,5-Me2pz)2. Reaction of these didentate ligands with [NiBr2(DME)] is a straightforward procedure that allows the synthesis of the nickel(II) complexes [NiBr2{RCH(3,5-Me2pz)2}]. The molecular structure of compound (R=CH2Ph) has been determined by X-ray diffraction studies. The nickel centre coordinates two bromine and two nitrogen atoms in a tetrahedral environment, and the metallacycle Ni(NN)2C adopts a boat conformation with the benzyl group in an axial position. 1H NMR studies have been carried out to characterize these paramagnetic nickel compounds in solution. Valuable information about the disposition of the ligands and dendritic wedges in solution has been obtained thanks to the influence of the paramagnetic centre on the proton resonances. 相似文献
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47.
Barrios CA Bañuls MJ González-Pedro V Gylfason KB Sánchez B Griol A Maquieira A Sohlström H Holgado M Casquel R 《Optics letters》2008,33(7):708-710
We demonstrate label-free molecule detection by using an integrated biosensor based on a Si(3)N(4)/SiO(2) slot-waveguide microring resonator. Bovine serum albumin (BSA) and anti-BSA molecular binding events on the sensor surface are monitored through the measurement of resonant wavelength shifts with varying biomolecule concentrations. The biosensor exhibited sensitivities of 1.8 and 3.2 nm/(ng/mm(2)) for the detection of anti-BSA and BSA, respectively. The estimated detection limits are 28 and 16 pg/mm(2) for anti-BSA and BSA, respectively, limited by wavelength resolution. 相似文献
48.
Cover Picture: A Versatile Approach to CF3‐Containing 2‐Pyrrolidones by Tandem Michael Addition–Cyclization: Exemplification in the Synthesis of Amidine Class BACE1 Inhibitors (Chem. Eur. J. 33/2015) 下载免费PDF全文
49.
Noemí?Andrade-LópezEmail author José?G.?Alvarado-Rodríguez Benito?Flores-Chávez 《Journal of chemical crystallography》2005,35(3):191-196
Reaction of 2-aminomethylpyridine with diphenylborinic acid in a mixture of CHCl3-diethyl ether gives diphenyl-(2-aminomethylpyridine-N,N)borane, a cyclic adduct that in presence of environmental moisture yields the N-8-(diphenyl-hydroxy-2-aminomethylpyridine)borane. The two compounds were characterized by NMR and infrared spectroscopy. The structure of N-8-(diphenyl-hydroxy-2-aminomethylpyridine)borane was confirmed by X-ray diffraction. This adduct crystallizes in monoclinic P21/n space group with unit cell dimensions: a = 13.193(2) (Å), b = 5.913(7) (Å), c = 19.604(2) (Å), = 90.295(3), V = 1529.3(3) Å3, Z = 4. The BN distance is 1.645(3) Å and lies in the range of a dative bond. The NH and OH groups are involved in intermolecular hydrogen bonds formation and they add to the stabilization of the acyclic adduct in the solid state. 相似文献
50.
Alcaide B Almendros P Cabrero G Ruiz MP 《Chemical communications (Cambridge, England)》2008,(5):615-617
Molecular iodine (10 mol%) efficiently catalyzes the ring expansion of 4-oxoazetidine-2-carbaldehydes in the presence of tert-butyldimethyl cyanide to afford protected 5-cyano-3,4-dihydroxypyrrolidin-2-ones with good yield and high diastereoselectivity, through a novel C3-C4 bond cleavage of the beta-lactam nucleus. 相似文献