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641.
Juan C. Castillo Rodrigo Abonía Michael B. Hursthouse Justo Cobo Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(2):o64-o66
The molecule of the title compound, C23H27N3O2, adopts a conformation having no internal symmetry so that the compound exhibits conformational chirality. The molecules are linked by a combination of C—H...O and C—H...π(arene) hydrogen bonds into a chain of rings in which two types of centrosymmetric ring alternate. 相似文献
642.
Joachim Roll Heiko Tewes Eduardo Castillo Soto Enrique Oate Rodríguez 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(2):m43-m45
The title compound, [W(C5H5)(HOBF3)(CO)3], has a four‐legged piano‐stool geometry which is typically found for C5H5W(CO)3X complexes. The HOBF3− anion is the hydrolysis product of BF4− and is coordinated via oxygen. 相似文献
643.
Enrique Castillo Francisco Jubete 《International Journal of Mathematical Education in Science & Technology》2013,44(3):369-389
In this paper the power of the Γ-algorithm for obtaining the dual of a given cone and some of its multiple applications is discussed. The meaning of each sequential tableau appearing during the process is interpreted. It is shown that each tableau contains the generators of the dual cone of a given cone and that the algorithm updates the dual cone when new generators are incorporated. This algorithm, which is based on the duality concept, allows one to solve many problems in linear algebra, such as determining whether or not a vector belongs to a cone, obtaining the minimal representations of a cone in terms of a linear space and an acute cone, obtaining the intersection of two cones, discussing the compatibility of linear systems of inequalities, solving systems of linear inequalities, etc. The applications are illustrated with examples. 相似文献
644.
Molybdenum oxide thin films have been successfully prepared by direct UV irradiation of amorphous films of a molybdenum dioxide acetylacetonate complex on Si(1 0 0) substrates. Photodeposited films were characterized by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) and the surface morphology examined by Atomic Force Microscopy (AFM). It was found that as-photodeposited films are uniform and smooth, with thickness of 350 nm, with rms surface roughness of 28 nm and contain non-stoichiometric oxides (MoO3−x). The results of XRD analysis showed that post-annealing of the films in air at 450 °C transforms the sub-oxides to α-MoO3 phase with a much rougher surface morphology (rms = 144 nm). The as-photodeposited MoO3−x films are amorphous, and exhibit better optical quality than annealed films. 相似文献
645.
J. A. Roldán Nofuentes J. D. Luna del Castillo P. Femia Marzo 《Computational Statistics》2009,24(4):695-718
In the presence of partial verification of the disease, confidence interval estimation for the difference of sensitivities
and specificities cannot be carried out by applying confidence intervals for the difference of binomial proportions, and the
comparison of the accuracy of the two binary tests cannot be carried out by applying McNemar’s test. In this article we propose
two methods for comparing the accuracy of two binary tests in the presence of partial verification of the disease. The first
method is based on the application of the EM and SEM algorithms, and the second method consists of the calculation of confidence
intervals for the difference in sensitivities and specificities applying confidence intervals for the difference in the two
binomial proportions from the last table obtained applying the EM algorithm. We carried out simulation experiments in order
to study and compare the coverage of several confidence intervals for the difference of the sensitivities and specificities. 相似文献
646.
Dr. Luca Bellarosa Dr. Juan Manuel Castillo Prof. Thijs Vlugt Dr. Sofía Calero Prof. Núria López 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(39):12260-12266
Increasing the resistance to humid environments is mandatory for the implementation of isoreticular metal–organic frameworks (IRMOFs) in industry. To date, the causes behind the sensitivity of [Zn4(μ4‐O)(μ‐bdc)3]8 (IRMOF‐1; bdc=1,4‐benzenedicarboxylate) to water remain still open. A multiscale scheme that combines Monte Carlo simulations, density functional theory and first‐principles Born–Oppenheimer molecular dynamics on IRMOF‐1 was employed to unravel the underlying atomistic mechanism responsible for lattice disruption. At very low water contents, H2O molecules are isolated in the lattice but provoke a dynamic opening of the terephthalic acid, and the lattice collapse occurs at about 6 % water weight at room temperature. The ability of Zn to form fivefold coordination spheres and the increasing basicity of water when forming clusters are responsible for the displacement of the organic linker. The present results pave the way for synthetic challenges with new target linkers that might provide more robust IRMOF structures. 相似文献
647.
Pérez-Yáñez S Beobide G Castillo O Cepeda J Fröba M Hoffmann F Luque A Román P 《Chemical communications (Cambridge, England)》2012,48(6):907-909
The presence of butanoic acid excess in the reaction media employed for the synthesis of a MOF with formula [Cu(2)(μ(3)-ade)(2)(μ(2)-OOC(CH(2))(2)CH(3))(2)](n) (ade: adeninate) leads to the formation of micelles that exert a template effect and provide a pronounced increase of its microporosity, doubling the intrinsic adsorption capacity of the pristine crystal network. 相似文献
648.
M Lanchas D Vallejo-Sánchez G Beobide O Castillo AT Aguayo A Luque P Román 《Chemical communications (Cambridge, England)》2012,48(79):9930-9932
The direct acid-base reaction between ZnO/CoO/Co(OH)(2) and imidazolic ligands under moderate heating (100-160 °C), in a closed vessel, leads to the generation of the corresponding zinc/cobalt-imidazolates in a high yield (87-97%) in which network topology is controlled by the addition of small amounts of structure directing agents. Moreover, the fine tuning of the thermal process at the synthetic stage permits us to increase the crystal size, and even to grow X-ray quality single crystals. 相似文献
649.
Djalma Souza Teresa Eligio Castillo Rubén Jésus Sánchez Rodríguez 《Journal of Thermal Analysis and Calorimetry》2012,109(3):1353-1364
Thermal stability of polymers is an important parameter that determines the application as well as the processing conditions. The green polymers have shown low thermal stability, such as the polyhydroxyalkanoates (PHAs). The PHAs with different comonomers containing hydroxyvalerate (HV) were studied. It was seen that the green polymer showed a fast thermal degradation process. The addition of the HV comonomer modified this profile and the thermal degradation kinetic. The blend prepared between the PHAs and other polymers can modify the thermal degradation process of the green polymers. In the present study, blends of cellulose acetate propionate and PHAs were prepared, and the thermal degradation kinetics of these blends were evaluated. It was observed that the cellulose acetate propionate (CAP) phase in the blends modified the thermal degradation process and kinetic profile of the PHA phase. In the blends, the thermal stability of the PHAs was slightly modified because of CAP reducing the reactivity of the PHAs. On the other hand, the thermal stability of the CAP phase in the blends is not largely modified by the PHA phase. However, the hydroxyvalerate comonomer decreases the reactivity of the CAP phase at the start of thermal degradation of the same. The interaction between the phases promotes the synergetic interaction, which slightly improves the thermal stability of the two polymers blends. 相似文献
650.
O'Reilly ME Del Castillo TJ Abboud KA Veige AS 《Dalton transactions (Cambridge, England : 2003)》2012,41(8):2237-2246
The oxygen-atom-transfer (OAT) from [(t)BuOCO]Cr(V)(O)(THF) (2) (where (t)BuOCO = [2,6-C(6)H(3)(6-(t)BuC(6)H(3)O)(2)](3-), THF = tetrahydrofuran) to triphenylphosphine (PPh(3)) in THF produces [(t)BuOCO]Cr(III)(THF)(3) (1) and triphenylphosphine oxide (OPPh(3)) at a rate of 69.5(±1.9) M(-1) s(-1) (22 °C). Identical rate constants were attained when acetonitrile (MeCN) and dichloromethane/THF (CH(2)Cl(2)/THF) were used as solvents. Electron paramagnetic resonance (EPR) data shows that the six-coordinate complex, [(t)BuOCO]Cr(V)(O)(THF)(2) (2a) forms upon addition of THF to 2, suggesting 2a as the active OAT species in THF. Similarly, addition of OPPh(3) has no influence on the rate of OAT, but the addition of triphenylphosphorus ylide (CH(2)PPh(3)) to form [(t)BuOCO]Cr(V)(O)(CH(2)PPh(3)) (4) prevents OAT to PPh(3). In CH(2)Cl(2), a [Cr(IV)](2)(μ-O) intermediate forms during the OAT from 2 to PPh(3). The OAT from {[(t)BuOCO]Cr(IV)(THF)}(2)(μ-O) (3) to PPh(3) reveals a zero-order dependence in PPh(3) indicating the dimer must first dissociate prior to OAT. The decay of 3versus time does not follow first-order kinetics due to the formation of a [(t)BuOCO]Cr(III)(THF) species (5) that inhibits the dissociation of 3. The change in concentration of 3versus time during OAT was simulated to obtain approximate rate constants. 相似文献