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81.
The seed oils of I.pseudacorus LINN ., I.sibirica LINN ., and I.missouriensis NUTTAL . contain appreciable amounts of phenols, quinones, and resorcinols, substituted with homologous alkyl or alkenyl side chains. The structure elucidation of these compounds is described, and their possible biosynthesis is discussed. 相似文献
82.
83.
84.
Elmer Vilsmaier Manfred Regitz 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》1991,103(8):1065-1066
85.
Elmer Ccopa Rivera Aline C. da Costa Maria Regina Wolf Maciel Rubens Maciel Filho 《Applied biochemistry and biotechnology》2006,132(1-3):969-984
In this present article, genetic algorithms and multilayer perceptron neural network (MLPNN) have been integrated in order
to reduce the complexity of an optimization problem. A data-driven identification method based on MLPNN and optimal design
of experiments is described in detail. The nonlinear model of an extractive ethanol process, represented by a MLPNN, is optimized
using real-coded and binary-coded genetic algorithms to determine the optimal operational conditions. In order to check the
validity of the computational modeling, the results were compared with the optimization of a deterministic model, whose kinetic
parameters were experimentally determined as functions of the temperature. 相似文献
86.
Noland WE Konkel MJ Konkel LM Pearce BC Barnes CL Schlemper EO 《The Journal of organic chemistry》1996,61(2):451-454
Four of the previously reported compounds obtained from the acid-catalyzed condensation of indole with acetone are now assigned the following structures: cis-4,4a,9,9a-tetrahydro-2-(1H-indol-3-yl)-4,4-dimethyl-3H-carbazole (2a), 1,1',4,4'-tetrahydro-1,1,1',1'-tetramethyl-3,3'(2H,2'H)-spirobi[cyclopent[b]indole] (4), 4,4a-dihydro-2-(3-1H-indolyl)-4,4-dimethyl-3H-carbazol-4a-ol (7), and 5-(2-aminophenyl)-1,3,4,5-tetrahydro-1,1,4,4-tetramethylcyclopent[kl]acridine (8). The structure of the novel rearrangement product 8 was solved by an X-ray crystal structure determination. The two previously reported autoxidation products of 4 are now assigned the following structures: 1,3',4,4'-tetrahydro-1,1,4',4'-tetramethyl-cis-dispiro[cyclopent[b]indole-3(2H),2'(5'H)-furan-5',3"-[3H]-indol]-2"(1"H)-one (5) and 1,4-dihydro-1,1,5',5'-tetramethylspiro[cyclopent[b]indole-3(2H),3'(4'H)-1-benzazocine]-2'(1'H),6'(5'H)-dione (6). 相似文献
87.
A series of ligands containing linked 1,4,7-triazacyclononane macrocycles are studied for the preparation of dinuclear Zn(II) complexes including 1,3-bis(1,4,7-triazacyclonon-1-yl)-2-hydroxypropane (L2OH), 1,5-bis(1,4,7-triazacyclonon-1-yl)pentane (L3), 2,9-bis(1-methyl-1,4,7-triazacyclonon-1-yl)-1,10-phenanthroline (L4), and alpha,alpha'-bis(1,4,7-triazacyclonon-1-yl)-m-xylene (L5). The titration of these ligands with Zn(NO(3))(2) was monitored by (1)H NMR. Each ligand was found to bind two Zn(II) ions with a very high affinity at near neutral pH under conditions of millimolar ligand and 2 equiv of Zn(NO(3))(2). In contrast, a stable mononuclear complex was formed in solutions containing 5.0 mM L2OH and 1 equiv of Zn(NO(3))(2). (1)H and (13)C NMR spectral data are consistent with formation of a highly symmetric mononuclear complex Zn(L2OH) in which a Zn(II) ion is sandwiched between two triazacyclononane units. The second-order rate constant k(Zn) for the cleavage of 2-hydroxypropyl-4-nitrophenyl phosphate (HPNP) at pH 7.6 and 25 degrees C catalyzed by Zn(2)(L2O) is 120-fold larger than that for the reaction catalyzed by the closely related mononuclear complex Zn(L1) (L1 = 1,4,7-triazacyclononane). By comparison, the observation that the values of k(Zn) determined under similar reaction conditions for cleavage of HPNP catalyzed by the other Zn(II) dinuclear complexes are only 3-5-fold larger than values of k(Zn) for catalysis by Zn(L1) provides strong evidence that the two Zn(II) cations in Zn(2)(L2O) act cooperatively in the stabilization of the transition state for cleavage of HPNP. The extent of cleavage of an oligoribonucleotide by Zn(L1), Zn(2)(L5), and Zn(2)(L2O) at pH 7.5 and 37 degrees C after 24 h incubation is 4,10, and 90%. The rationale for the observed differences in catalytic activity of these dinuclear Zn(II) complexes is discussed in terms of the mechanism of RNA cleavage and the structure and speciation of these complexes in solution. 相似文献
88.
Franz-Josef Drexler 《Numerische Mathematik》1977,29(1):45-58
Summary In this paper a numerical method is given to compute all solutions of systemsT ofn polynomial equations inn unknowns on the only premises that the sets of solutions of these systems are finite. The method employed is that of embedding, i.e. the systemT is embedded in a set of systems which are successively solved, starting with one having solutions easily to compute and proceding toT in a finite series of steps. An estimation of the number of steps necessary is given. The practicability of the method is proved for all systemsT. Numerical examples and results are contained.
Diese Arbeit ist eine Zusammenfassung der Ergebnisse der Dissertation, die der Verfasser an der Johannes-Kepler-Universität Linz und der Technischen Universität München unter der Betreuung von Prof. Dr. Hansjörg Wacker angeferetigt hat. 2. Begutachter: Prof. Dr. Manfred Feilmeier 相似文献
89.
Jonathan Elmer 《Archiv der Mathematik》2008,91(6):481-485
Let G be a finite group acting linearly on a finite dimensional vector space V defined over a field k of characteristic p, where p is assumed to divide the group order. Let R := S(V *) be the symmetric algebra of the dual on which G acts naturally by algebra automorphisms. We study the RG-modules Hi(G, R) for i > 0. In particular we give a formula which describes the annihilator of a general element of Hi(G, R) in terms of the relative transfer ideals of RG, and consequently prove that the associated primes of these cohomology modules are equal to the radicals of certain relative
transfer ideals.
Received: 5 June 2008 相似文献
90.
Alvarez VH Rivera EC Costa AC Filho RM Wolf Maciel MR Aznar M 《Applied biochemistry and biotechnology》2008,148(1-3):141-149
In this work, the phase equilibrium of binary mixtures for bioethanol production by continuous extractive process was studied.
The process is composed of four interlinked units: fermentor, centrifuge, cell treatment unit, and flash vessel (ethanol-congener
separation unit). A proposal for modeling the vapor–liquid equilibrium in binary mixtures found in the flash vessel has been
considered. This approach uses the Predictive Soave–Redlich–Kwong equation of state, with original and modified molecular
parameters. The congeners considered were acetic acid, acetaldehyde, furfural, methanol, and 1-pentanol. The results show
that the introduction of new molecular parameters r and q in the UNIFAC model gives more accurate predictions for the concentration of the congener in the gas phase for binary and
ternary systems. 相似文献