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71.
72.
Duraiswamy SukanyaDuraisamy Senthil Raja Nattamai S.P. BhuvaneshKaruppannan Natarajan 《Polyhedron》2011,30(6):1108-1113
New hexa-coordinated Ru(III) complexes of the type [Ru(H2Pzdc)(EPh3)3X2] have been synthesized by reacting 3,5-pyrazole dicarboxylic acid (H3Pzdc) with the appropriate starting complexes [RuX3(EPh3)3] (where X = Cl or Br; E = P or As). The ligand behaves as a bidentate monobasic chelate. All the complexes have been characterized by analytical and spectroscopic (IR, electronic and EPR) data. Single-crystal X-ray analysis of the complex [Ru(H2Pzdc)(PPh3)2Cl2]·C6H6·C2H5OH revealed that the coordination environment around the ruthenium center consists of an NOP2Cl2 octahedron. The planar ligand occupies the equatorial position along with two chlorine atoms, while the triphenylphosphine groups occupy the axial positions. The electrochemical behavior of the new complexes was studied using cyclic voltammetry. The new mononuclear ruthenium complexes are capable of acting as catalysts for the oxidation of alcohols. 相似文献
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An innovative conductometric measurement technique using a nonconventional but high‐performance (high‐precision, high‐resolution, rapid response features for online graphic display) in house–built pulsating conductivity monitoring instrument has been deployed to study the kinetic behavior during the reaction of ethyl acetate and NaOH. A laboratory‐made constant temperature reaction bath with the facility of continuous stirring of solution for homogeneous mixing was used to carry out experiments at desired solution temperatures. Rate constants of the saponification reaction in the temperature range at various temperatures (30–55°C) were determined, and the results were compared with the reported values. Although the reported data exhibit wide scatter, our data are in agreement with some of the literature data. From these data, thermodynamic parameters such as activation energy, activation enthalpy, activation entropy, and activation free energy have been evaluated. With the introduction of this novel conductometric measurement technique, the determination of rate constants at various solution temperatures becomes much simpler and faster. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 648–656, 2011 相似文献
76.
The enantioselective cyclization of the prochiral cyclic substrates1 to7 and26, can be carried out in theneat using S-proline as catalyst. The substrates18 to22 and27 could not be cyclized with S-proline but could be cyclized with a mixture of S-phenylalanine and d-camphorsulphonic acid.
The enantioselective cyclization of prochiral acyclic triones45 and47 and also the racemic tricarbonyl compounds54 to57 could also be carried out in theneat using S-proline as catalyst. The optically active enediones obtained in the above cyclizations could also be obtained directly
from 1,3-diones or 2-hydroxymethylene cycloalkanones in a one-pot reaction with methyl vinyl ketone (MVK) and S-proline in
the absence of solvents.13C NMR studies of the one-pot synthesis ofS-11 andS-14 reveal that the annulations involve initial formation of an acid-base complex followed by a Michael reaction and then an
enantioselective cyclization. Such enantioselective cyclizations probably occur on the surface of S-proline crystals. 相似文献
77.
Gautam Gundiah M Eswaramoorthy S Neeraj Srinivasan Natarajan C N R Rao 《Journal of Chemical Sciences》2001,113(3):227-234
Mesoporous aluminosilicate spheres of 0.3–0.4 Μm diameter, with different Si/Al ratios, have been prepared by surfactant templating.
Surface area of these materials is in the 510–970 m2 g-1 range and pore diameter in the 15–20 ? range. 相似文献
78.
QSAR modeling of flotation collectors using principal components extracted from topological indices 总被引:1,自引:0,他引:1
Natarajan R Nirdosh I Basak SC Mills DR 《Journal of chemical information and computer sciences》2002,42(6):1425-1430
Several topological indices were calculated for substituted-cupferrons that were tested as collectors for the froth flotation of uranium. The principal component analysis (PCA) was used for data reduction. Seven principal components (PC) were found to account for 98.6% of the variance among the computed indices. The principal components thus extracted were used in stepwise regression analyses to construct regression models for the prediction of separation efficiencies (Es) of the collectors. A two-parameter model with a correlation coefficient of 0.889 and a three-parameter model with a correlation coefficient of 0.913 were formed. PCs were found to be better than partition coefficient to form regression equations, and inclusion of an electronic parameter such as Hammett sigma or quantum mechanically derived electronic charges on the chelating atoms did not improve the correlation coefficient significantly. The method was extended to model the separation efficiencies of mercaptobenzothiazoles (MBT) and aminothiophenols (ATP) used in the flotation of lead and zinc ores, respectively. Five principal components were found to explain 99% of the data variability in each series. A three-parameter equation with correlation coefficient of 0.985 and a two-parameter equation with correlation coefficient of 0.926 were obtained for MBT and ATP, respectively. The amenability of separation efficiencies of chelating collectors to QSAR modeling using PCs based on topological indices might lead to the selection of collectors for synthesis and testing from a virtual database. 相似文献
79.
80.
Five new open-framework zinc phosphates, encompassing the entire hierarchy of open-framework structures, have been synthesized hydrothermally in the presence of triethylenetetramine. The structures include one-dimensional ladders, two-dimensional layers, and three-dimensional structures as well as a zinc phosphate where the amine acts as a ligand. [C6N4H22]0.5[Zn(HPO4)2] (I): monoclinic, space group P2(1)/c (no. 14), a = 5.2677(1) A, b = 13.3025(1) A, c = 14.7833(1) A, beta = 96.049 degrees, Z = 4. [C6N4H22]0.5[Zn2(HPO4)3] (II): triclinic, space group P1 (no. 2), a = 7.515(1) A, b = 8.2553(1) A, c = 12.911(1) A, alpha = 98.654(1) degrees, beta = 101.274(1) degrees, gamma = 115.791(1) degrees, Z = 2. [C6N4H22]0.5[Zn2P2O8] (III): triclinic, space group P1 (no. 2), a = 8.064(1) A, b = 8.457(1) A, c = 9.023(1) A, alpha = 111.9(1) degrees, beta = 108.0(1) degrees, gamma = 103.6(1) degrees, Z = 2. [C6N4H22]0.5[Zn3(PO4)2(HPO4)] (IV): triclinic, space group P1 (no. 2), a = 5.218(1) A, b = 8.780(1) A, c = 16.081(1) A, alpha = 89.3(1) degrees, beta = 83.5(1) degrees, gamma = 74.3(1) degrees, Z = 2. [C6N4H20]0.5[Zn4P4O16] (V): monoclinic, space group P2(1)/c (no. 14), a = 9.219(1) A, b = 15.239(1) A, c = 10.227(1) A, beta = 105.2(1), Z = 4. The structure of I is composed of ZnO4 and HPO4 tetrahedra, which are edge-shared to form four-membered rings, which, in turn, form a one-dimensional chain (ladder). In II, these ladders are fused into a layer. The structures of III and IV comprise networks of ZnO4 and PO4 tetrahedra forming three-dimensional architectures. In V, the amine molecule coordinates to the Zn and acts as a pillar supporting the zinc phosphate layers, which possess infinite Zn-O-Zn linkages. The 16-membered one-dimensional channel in IV and the ZnO3N pillar, along with infinite Zn-O-Zn linkages in V, are novel features. The structure of the open-framework zinc phosphates is found to depend sensitively on the relative concentrations of the amine and phosphoric acid, with high concentrations of the latter favoring structures with lower dimensions. 相似文献