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排序方式: 共有512条查询结果,搜索用时 15 毫秒
431.
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433.
FANG Yuan HEYDARI Zahra LIU Chenghao ZHANG Nianyue CUCCIA Louis A. IVASENKO Oleksandr PEREPICHKA Dmitrii F. 《高等学校化学研究》2021,37(5):1143-1148
The direct polymerization via irreversible C-C coupling on inert substrates will give access to new low-dimensional advanced functional materials and simplify their industrial fabrication. In this work, we present our initial results in the application of Glaser coupling to the direct on-surface polymerization of a model diacetylene compound at the solid-vapor interface. The self-assembly of the monomer and polymerization products was characterized using scanning tunneling microscopy (STM). In addition, selected optical properties and the electronic structure of all compounds were investigated. 相似文献
434.
Valery A. Ozeryanskii Ekaterina A. Filatova Alexander F. Pozharskii Dmitrii A. Shevchuk Vladimir I. Sorokin 《Journal of Physical Organic Chemistry》2013,26(6):492-502
Through‐conjugation for a wide range of 1,8‐diamino‐4,5‐dinitronaphthalenes (N‐acylated, N‐alkylated, N,N′‐bridged, N‐heterocyclic, and N‐deprotonated compounds) was for the first time quantified in solution by means of ultraviolet–visible and proton nuclear magnetic resonance spectroscopy and compared with that of the simpler naphthalene and benzene push‐pull systems. Surprisingly, an extent of conjugation in 1,8‐diamino‐4‐nitro‐ and 1,8‐diamino‐4,5‐dinitronaphthalenes measured in dimethyl sulfoxide is commensurable. On the whole, the repulsive peri‐interactions between the amino groups in systems with N‐alkylated and N‐deprotonated amino groups are more favorable for an effective D‐π‐A charge transfer than in N,N′‐bridged compounds (perimidines, 2,3‐dihydroperimidines and perimidin‐2‐ones). The best electron donors from peri‐positions are pyrrolidin‐1‐yl and methylamido groups. The conclusions obtained from solution studies were deepened by solid‐ state X‐ray experiments for a number of push–pull naphthalenes, including 6,7‐dinitroperimidine N‐anion and two representatives of 4,5‐diaminonaphthalene‐1,8‐dicarbaldehydes. In particular, they helped to trace changes in the bond order redistribution and twisting of the naphthalene core. The latter reaches a record value of 27° for 4,5‐dinitro‐1,8‐di(pyrrolidin‐1‐yl)naphthalene. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
435.
In this paper we provide a complete list of spin-2 cubic interaction vertices with two derivatives. We work in (anti) de Sitter space with dimension d?4 and arbitrary value of cosmological constante and use simple metric formalism without any auxiliary or Stueckelberg fields. We separately consider cases with one, two and three different spin-2 fields entering the vertex where each field may be massive, massless or partially massless one. The connection of our results with massive (bi)gravity theories is also briefly discussed. 相似文献
436.
Limits of Coherent Addition of Lasers: Simple Estimate 总被引:1,自引:0,他引:1
Dmitrii Kouznetsov Jean-François Bisson Akira Shirakawa Ken-ichi Ueda 《Optical Review》2005,12(6):445-447
The coherent combining of single mode lasers using coupled cavities is considered. A simple analytical estimate of the number
of lasers that can be efficiently combined in such a way is suggested. Such an estimate agrees with simulations and experiments
reported recently. 相似文献
437.
Dmitrii O Berbasov 《Journal of fluorine chemistry》2004,125(4):603-607
The standard reaction conditions commonly used for the condensation of carbonyl compounds with amines were found to be synthetically inefficient for preparation of the imines derived from trifluoroacetophenone and benzylamines owing to the susceptibility of these imines to 1,3-proton shift. Application of a “low-basicity” method, using instead of free benzylamines their salts formed from acetic acid (AA), allowed synthesis of the target compounds in chemically pure form and excellent chemical yields. 相似文献
438.
439.
Marina Shelyapina Irina Zvereva Liliya Yafarova Dmitrii Bogdanov Stanislav Sukharzhevskii Yurii Zhukov Vitalii Petranovskii 《Journal of Thermal Analysis and Calorimetry》2018,131(1):71-79
The main work of this thesis is to study and discuss flame-retardant properties of the flexible polyurethane foam (FPUF) added with borax, expanded graphite (EG), and EG/Borax as flame retardant, respectively. The thermal behavior of samples has been using thermogravimetry (TG) and differential thermogravimetry in air. The activation energies for different stages of thermal degradation are obtained following the equation of Kissinger. The flammability parameters, including limiting oxygen index, rate of heat release, total heat release, yield of CO, yield of CO2, and smoke production rate, were recorded simultaneously. The char structure was studied by SEM, and their thermal stability and evolved gaseous products were examined by TG analysis–Fourier transform infrared spectroscopy. By analyzing these data, it was concluded that most combustion parameters of FPUF were decreased by the treatment, especially for EG/Borax treatment, which indicated a synergistic effect of flame retardancy. Meanwhile, the probable flame retardation mechanism was proposed. 相似文献
440.
Dmitrii Pyreu Sergei Gridchin Eugenii Kozlovskii 《Journal of Coordination Chemistry》2016,69(22):3424-3435
Calorimetric, potentiometric, and spectrophotometric studies on mixed ligand complexes of copper(II) iminodiacetate and simple di- and tripeptides (GlyGly, αAlaαAla, αAlaβAla, βAlaβAla, αAlaAsn, GlyGlyGly, AlaGlyGly) have been carried out in aqueous solution at 298.15 K and ionic strength of I = 0.5 (KNO3). The thermodynamic parameters of formation of various mixed complexes have been determined. The probable coordination modes of the complex and peptide molecules in the mixed ligand complexes are discussed. 相似文献