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51.
In this paper, highly active Ziegler-Natta catalysts of MgCl_2 supported TiCl_4 for synthesis ofpolyolefins, using di-n-butyl phthalate (DNBP) as internal donor and diphenyl dimethoxyl silane(DPDMS) as external donor, have been prepared. The conditions controlling the treatment ofsupport were studied. The interactions of various components present in the catalysts and theirinfluences on catalytic performance were investigated. It is found that by using DNBP and DPDMSas internal and external donors together the polymer products with higher isotactic index can beobtained. Plausible structure model and mechanism were proposed. 相似文献
52.
53.
U. M. Dzhemilev A. G. Ibragimov A. B. Morozov R. R. Muslukhov G. A. Tolstikov 《Russian Chemical Bulletin》1992,41(6):1089-1093
A new stereoselective method is developed for the synthesis of 1-chloro-, 1-alkoxy-, and 1-N,N-dialkylaminoalumino-cyclopentanes from -olefins, metallic magnesium, and aluminum halides (AlCl3, RO-AlCl2, R2N-AlCl2) in the presence of catalytic amounts of Cp2ZrCl2 (Cp=5-C5H5). The products from hydrolysis and deuterolysis of the Al-substituted 3,4-dialkylaluminocyclopentanes (ACP) have the threo configuration.For Communication 8, see [1].Institute of Organic Chemistry, Urals Branch, Russian Academy of Sciences, 450054 Ufa. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1393–1397, June, 1992. 相似文献
54.
Fe_2O_3/ZrO_2催化剂上一氧化碳加氢反应制低碳烯烃──I.催化剂反应性能及反应过程中铁物相的变化 总被引:1,自引:0,他引:1
用浸渍法制得一系列不同铁负载量的Fe2O3/ZrO2催化剂,应用催化反应评价结合穆斯堡尔谱对催化剂的CO加氢反应性能、催化剂活性相结构及催化剂铁物种在合成气反应过程中的物相变化进行了研究.结果表明,铁负载量的大小对于Fe2O3/ZrO2催化剂的F-T反应催化性能有很大影响,铁负载量适当时,Fe2O3/ZrO2催化剂铁锆间适当的强相互作用使得催化剂在保持较高催化活性的同时高选择性地生成低碳烯烃,产物分布偏离Schulz-Flory分布规律. 相似文献
55.
Krzysztof Winkler Alan L. Balch Włodzimierz Kutner 《Journal of Solid State Electrochemistry》2006,10(10):761-784
The recent results of investigations involving the electrochemical formation of polymers containing fullerenes and studies of their properties and applications are critically reviewed. From a structural point of view, these polymers can be divided into four main categories including (1) polymers with fullerenes physically incorporated into the foreign polymeric network without forming covalent bonds, (2) fullerene homopolymers formed via [2+2] cycloaddition, (3) “pearl necklace” polymers with fullerenes mutually linked covalently to form polymer chains, and (4) “charm bracelet” polymers containing pendant fullerene substituents. The methods of electrochemical polymerization of these systems are described and assessed. The structural features and properties of the electrochemically prepared polymers and their chemically synthesized analogs are compared. Polymer films containing fullerenes are electroactive in the negative potential range due to electroreduction of the fullerene moieties. Related films made with fullerenes derivatized with electron-donating moieties as building blocks are electroactive in both the negative and positive potential range. These can be regarded as “double cables” as they exhibit both p- and n-doping properties. Fullerene-based polymers may find numerous applications. For instance, they can be used as charge-storage and energy-converting materials for batteries and photoactive units of photovoltaic cell devices, respectively. They can be also used as substrates for electrochemical sensors and biosensors. Films of the C60/Pt and C60/Pd polymers containing metallic nano-particles of platinum and palladium, respectively, effectively catalyze the hydrogenation of olefins and acetylenes. Laser ablation of electrochemically formed C60/M and C70/M polymer films (M=Pt or Ir) results in fragmentation of the fullerenes leading to the formation of hetero-fullerenes, such as [C59M]+ and [C69M]+.Dedicated to Professor Dr. Alan M. Bond on the occasion of his 60th birthday. 相似文献
56.
C4/C5烃催化裂解制低碳烯烃的研究进展 总被引:2,自引:0,他引:2
从催化剂类型、裂解工艺、催化裂解的影响因素和裂解机理4个方面对国内外C4/C5烃催化裂解制低碳烯烃的研究进行了综述。催化裂解制低碳烯烃催化剂主要采用ZSM-5分子筛系列催化剂,在此基础上发展了酸改性或水热改性高硅ZSM系列分子筛及介孔MCM-41分子筛。总结了国内外C4/C5烃的裂解工艺,认为影响催化裂解的主要因素是裂解原料、催化剂类型及工艺条件。目前,裂解机理主要是自由基与碳正离子机理相结合的机理。并简述了本课题组目前有关C4烷烃催化裂解的主要研究进展。 相似文献
57.
Dr. Tatsuya Yanagisawa Prof. Dr. Yoshiyuki Mizuhata Prof. Dr. Norihiro Tokitoh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(44):11273-11278
The reversible addition of olefins to a phosphanylalumane, P−Al single-bond species, was investigated. The P−Al bond added to ethylene and relatively small terminal alkenes (propylene and hex-1-ene) at room temperature to give the corresponding alkene adducts. Heating the terminal alkene adducts released the corresponding alkenes and regenerated the P−Al bond, but no release of ethylene was observed even under vacuum conditions. The reactivity of ethylene adduct as a new saturated C2 vicinal P/Al-based FLP was also investigated. The ethylene adduct was found to undergo complexation with nitriles to give the corresponding nitrile adducts to the Al center, which retained the ethylene tether as in the case of the corresponding P/B-based FLP. However, the reactivity of ethylene toward CO2 and benzaldehyde differed from that of the P/B system giving the corresponding adducts. 相似文献
58.
Robert Vallée 《International Journal of Mathematical Education in Science & Technology》2013,44(2):141-144
Inside the scientific world it is not always understood that the mood of mathematics, which is a product and a part of culture, can change with time. This is partly why many have been surprised by the coming of the so‐called new mathematics. In the truly creative mathematical mind two opposite tendencies coexist: the logical and the imaginative. Apparently it seems that new mathematics can be reduced to a purely logical machinery. In fact it contains as much imaginative contributions as classical mathematics. But it is difficult to show simultaneously the logical sequence of propositions and the clumsy progression of research itself. Mathematical exposition does not always follow the ‘ most natural slopes’ of the mind. Unfamiliar presentations often give an impression of ‘ abstraction ‘, more familiar ones an impression of concreteness ‘. So it appears that difficulties with new mathematics are mostly of psychological origin. Misuses of it can easily raise up intolerance reactions and emotional blocks. Perhaps insisting upon the fact that, here as elsewhere, it is important to be able to guess, to realize that intuition and imagination are essential, could help to make new mathematics better understood, more useful and more able to be considered as a unifing element among sciences. 相似文献
59.
Nanosized cationic and anionic manganese porphyrins as mesoporous catalysts for the oxidation of olefins: Nano versus bulk aggregates 下载免费PDF全文
In this study, catalytic activity of bulk and nano‐sized meso‐tetrakis(4‐sulfonatophenyl)porphyrinatomanganese(III) acetate, MnTPPS4(OAc), (ammonium salt) and meso‐tetrakis(3‐methylpyridyl)porphyrinatomanganese(III) acetate, MnT(3‐MePy)P(OAc) (tosylate salt) for the oxidation of olefins with tetra‐n‐butylammonium Oxone has been studied and compared with that of the bulk counterparts. The nanoparticles were prepared by mixing solvent techniques using water, (triethyleneglycol) monomethyl ether and dimethylsulfoxide or acetonitrile. The formation of nano‐sized catalysts was confirmed by UV‐Vis spectroscopy, DLS and AFM. Nitrogen porosimetry measurements indicated the homogeneous pore size distribution in the bulk and nano‐sized manganese porphyrins. In spite of the high oxidizability of Oxone, the heterogenized manganese porphyrins showed a significantly higher oxidative stability relative to their homogeneous counterparts within a reaction time of 6 h. The increase in the catalytic activity induced by the formation of nano‐sized catalysts was more pronounced in the case of MnT(3‐MePy)P(OAc). MnT(3‐MePy)P(OAc) may be recovered and reused for at least 4 times without any significant decrease in the catalyst efficiency. In the case of MnTPPS4(OAc) a large decrease in the catalytic activity was observed after the first use of the catalyst. The latter was attributed to higher degrees of catalyst degradation in the case of MnTPPS4(OAc). 相似文献
60.