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51.
R. A. Manzhos Yu. M. Maksimov B. I. Podlovchenko 《Russian Journal of Electrochemistry》2005,41(8):832-837
Transients of the open-circuit potential, which are observed during the interaction of formic acid with preliminarily adsorbed oxygen (Oads) on a Pt/Pt electrode in 0.5 M H2SO4, are measured. It is established, by means of the method of cathodic potentiodynamic pulses, that the slowest interaction of formic acid with Oads occurs in the region of large coverages of the electrode surface by oxygen (θO ∼1–0.8). A presumption is put forward that the process rate in this region is defined by a direct reaction of Oads with molecules of formic acid from the bulk solution. It is shown that the interaction of formic acid with Oads in the region of intermediate coverages (θO ∼ 0.8–0.2) proceeds via a mechanism of “conjugated reactions.” Transients of the open-circuit potential for formic acid are compared to transients for carbon monoxide obtained in analogous conditions. The substantially shorter overall time of potential decay in the case of CO (at the same concentrations) is caused by a faster reaction of CO with adsorbed oxygen in the region of large θO. The difference is explained by assuming that the HCOOH adsorption as opposed to CO bears a dissociative character.__________Translated from Elektrokhimiya, Vol. 41, No. 8, 2005, pp. 936–942.Original Russian Text Copyright © 2005 by Manzhos, Maksimov, Podlovchenko. 相似文献
52.
V. Slavinska Dz. Sile G. Rozenthal G. Maurops J. Popelis M. Katkevich V. Stonkus E. Lukevics 《Chemistry of Heterocyclic Compounds》2006,42(5):570-573
The hydrogenation of ethyl 4-R-2,4-dioxobutyrates (R = phenyl, 2-furyl) at 5% Pt/Al2O3 catalyst, modified with cinchonidine, and at palladium black was investigated. The former had low activity under the conditions
we tested. The main products during the hydrogenation of these compounds at palladium black are ethyl 4-R-2-hydroxy-4-oxobutyrates.
The yield of the phenyl derivative amounts to 68.5%, while the yield of the corresponding 2-furyl derivative amounts to 97%.
In the last case ethyl 2-hydroxy-4-oxo-4-(2-tetrahydrofuryl)butyrate was detected as impurity. The optimum conditions for
the formation of ethyl 2-hydroxy-4-phenylbutyrate (yield 88.2%) were determined.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 655–659, May, 2006. 相似文献
53.
R. S. Mitchenko A. A. Shubin T. V. Krasnyakova 《Theoretical and Experimental Chemistry》2006,42(5):314-319
A heterogeneous catalyst for the hydrochlorination of acetylene by gaseous HCl is formed as a result of mechanical treatment
of the solid salt K2PtCl4 in an atmosphere of acetylene, ethylene, or propylene by the formation of π complexes of platinum(II) as active centers in
the surface layer under these conditions. The controlling stage of the catalytic reaction is chloroplatination of the π-coordinated
acetylene by the HCl molecule. The reaction takes place as a concerted process, in which an intermediate β-chlorovinyl derivative
of platinum(II), a complex of platinum with a coordination vacancy[PtCl
3
*
]−, and a new molecule of HCl are formed simultaneously with cleavage of the H—Cl and Pt—Cl bonds in the metal complex adjacent
to the π-acetylene complex. The catalytic cycle closes with rapid dissociation of the organoplatinum intermediate by the action
of HCl, giving the final product and the initial complex [PtCl4]2−.
__________
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 5, pp. 306–311, September–October, 2006. 相似文献
54.
55.
A new series of DNA binding 5,10,15-tri(N-methyl-4-pyridiniumyl)porphyrin (TrisMPyP)-platinum(II) conjugates was synthesized, in which different spacer ligands were used for appropriate coordination to platinum(II) complexes. Compound 9b exhibited in vivo antitumor activity (T/C%, 294) superior to cisplatin (T/C%, 184) against the leukemia L1210 cell line. 相似文献
56.
Xinhuan Yan Junqing Sun Yongbin Fang Zhenyuan Xu Wenjing Wang 《Frontiers of Chemistry in China》2006,1(1):41-44
The Pt-Sn-B/carbon nanotubes (CNTs) catalyst was prepared by impregnation-chemical reduction method. Its catalytic performance
was evaluated by liquid-phase hydrogenation of chloronitrobenzene (CNB). The results showed that the catalyst had higher catalytic
performance than common hydrogenation catalysts. The conversion of CNB could reach 99.9%, and the dechlorination of chloroaniline
(CAN) was less than 1.9% when catalyzed by Pt-Sn-B/CNTs and more than 8.0% when catalyzed by common hydrogenation catalysts.
X-ray diffraction and selected area electron diffraction analysis showed that Pt-Sn-B/CNTs had an amorphous alloy structure
that can improve catalytic performance. Transmission electron micrograph image showed that the catalyst particles were highly
distributed on the surface of CNTs. The hydrodechlorination of CNB was mainly affected by the unique structure of CNTs and
the nature of the amorphous metals on the surface of CNTs. The relationship between the interaction of CNTs and amorphous
metals and the catalytic performance of the catalyst is also discussed.
Translated from the Chinese Journal of Catalysis, 2005, 26(3) (in Chinese) 相似文献
57.
V. Climent N. García-Araez E. Herrero J. Feliu 《Russian Journal of Electrochemistry》2006,42(11):1145-1160
The electrochemical behavior of platinum single-crystal electrodes is revisited, with special emphasis on the determination
of the potential of zero charge. We show that the measure of the charge displaced during CO adsorption allows the determination
of the potential of zero total charge (PZTC). The estimation of the potential of zero free charge (PZFC) is discussed, with
different degrees of approximation. The application of this methodology to the study of the PZTC of platinum stepped surfaces
vicinal to Pt(111) reveals a marked decrease of the PZTC due to the introduction of surface steps. This effect is interpreted
as the result of the existence of markedly smaller surface potentials localized on step sites. The importance of considering
local aspects of the interface is emphasized with the use of N2O reduction as a sensitive probe to the local structure of the surface. It is proposed that the different local maxima observed
in the absolute value of the reduction current correspond to the local values of PZTC. It is shown that there is, in general,
good agreement between the overall PZTC, obtained from the CO displacement, and that calculated from the local values inferred
from the N2O reduction. Further insight is obtained with the application of the laser-induced temperature jump method. This technique
is useful to calculate the potential of maximum entropy of the double-layer formation. The resulting value of this potential
for Pt(111) is discussed in the light of the PZFC value obtained from different approaches. For stepped surfaces vicinal to
Pt(111), two local maxima in the entropy of the double layer are observed that are close to the local PZTC values estimated
from the N2O reduction. This result suggests the existence of cooperative effects in the organization of the water dipoles close to the
electrode surface.
Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 11, pp. 1275–1292.
Based on the report delivered at the 8th International Frumkin Symposium “Kinetics of the Electrode Processes,” October 18–22,
2005, Moscow.
The text was submitted by the authors in English. 相似文献
58.
Tin dioxide nanoparticles of 5 nm in size were prepared on NaY zeolite external surface by impregnation of SnCl2 solution and subsequent calcination at 623 K. A SnO2-NaY based chemical sensor for detecting H2 was demonstrated. 相似文献
59.
Wang X Yu JC Yip HY Wu L Wong PK Lai SY 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(10):2997-3004
A novel metal/semiconductor nanocomposite with catalytic and photocatalytic functions has been prepared. The new material consists of highly dispersed platinum (Pt) nanoparticles embedded in a cubic mesoporous nanocrystalline anatase (meso-nc-TiO2) thin film. The porous thin film possesses a narrow pore-size distribution and a large surface area. The diameter of the Pt cluster can be controlled to below 5 nm, and the high dispersion of these clusters gives rise to catalytic activity for the oxidation of carbon monoxide, an important reaction for automobile exhaust treatment. This novel ordered mesoporous Pt/TiO2 nanoarchitecture is also a promising photochemical material, as demonstrated by the photo-driven killing of Micrococcus lylae cells on the film. 相似文献
60.
金橙G螯合形成树脂分离富集地质样品中的微量贵金属 总被引:10,自引:0,他引:10
主要研究了金橙G螯合形成树脂分离富集地质样品中金、铂、钯的最佳实验条件。在柱高大于16cm,0.1mol/L HCl介质的样品溶液以小于或等于0.5mL/min流速过柱,用0.1mol/L HCl的3%硫脲溶液以小于或等于0.5mL/min流速洗脱金、铂、钯(和铑),都能同时定量富集。用火焰原子吸收光谱法测定,回收率均在95% ̄110%之间。经地质样品加标准回收实验,结果令人满意。证明这种以磺酸基 相似文献