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排序方式: 共有97条查询结果,搜索用时 203 毫秒
81.
Agakishiev G Aggarwal MM Ahammed Z Alakhverdyants AV Alekseev I Alford J Anderson BD Anson CD Arkhipkin D Averichev GS Balewski J Barnby LS Beavis DR Behera NK Bellwied R Betancourt MJ Betts RR Bhasin A Bhati AK Bichsel H Bielcik J Bielcikova J Bland LC Bordyuzhin IG Borowski W Bouchet J Braidot E Brandin AV Bridgeman A Brovko SG Bruna E Bueltmann S Bunzarov I Burton TP Cai XZ Caines H Sánchez MC Cebra D Cendejas R Cervantes MC Chaloupka P Chattopadhyay S Chen HF Chen JH Chen JY Chen L Cheng J 《Physical review letters》2012,108(7):072301
We report new STAR measurements of midrapidity yields for the Λ, Λ[over ˉ], K(S)(0), Ξ(-), Ξ[over ˉ](+), Ω(-), Ω[over ˉ](+) particles in Cu+Cu collisions at √S(NN)==200 GeV, and midrapidity yields for the Λ, Λ[over ˉ], K(S)(0) particles in Au+Au at √S(NN)==200 GeV. We show that, at a given number of participating nucleons, the production of strange hadrons is higher in Cu+Cu collisions than in Au+Au collisions at the same center-of-mass energy. We find that aspects of the enhancement factors for all particles can be described by a parametrization based on the fraction of participants that undergo multiple collisions. 相似文献
82.
Jorge E. Muñoz Janeth Cervantes Rodrigo Esparza Gerardo Rosas 《Journal of nanoparticle research》2007,9(5):945-950
In this investigation, the chemical and structural characteristics of Fe nanoparticles synthesized by high-energy ball milling
have been explored. After the milling process the nanoparticles were collected using a magnetic field. The structure, morphology
and composition of the powders were obtained using high-resolution electron microscopy. HREM images confirmed the nanoparticles’
presence with approximately 2–4 nm in size. It was found that using this method allowed the formation of nanoparticles in
a smaller size range than other synthesis methods. Also, it was confirmed by HREM images that the obtained nanoparticles were
mainly of the fcc nature and some of them of the MTP type. 相似文献
83.
I. Cervantes J.C. Sanchez-Garcia F.J. Perez-Pinal 《Chaos, solitons, and fractals》2008,37(5):1511-1527
The aim of this paper is to characterize time and resonant behavior in a class of piece-wise linear systems evolving chaotically. To this end, statistical methods are used to reveal interactions of different parts of the system. The system under study comprises a continuous time subsystem and a switching rule that induces an oscillatory path by switching alternately between stable and unstable conditions. Since the system is not continuous, the principal oscillation frequency depends on the switching regime and linear subsystem parameters; therefore, many time and resonant patterns can be observed. It is shown that the system may display resonance produced by the action of a external signal (switching law), as well as internal and combinational resonance. The effect of system parameters on time evolution and resonance is studied. It is shown that the nature of subsystems eigenvalues plays a crucial role in the type of resonance observed, producing in some cases complex interaction of resonance modes. 相似文献
84.
Because natural silicates are potential sources of oligosiloxanes of the type QxMy, a collection of natural silicates of similar structure was used to obtain mainly Q2M6 oligosiloxanes by trimethylsilylation. The tailings from silver and gold flotation beneficiation provide an important silicate source. The main silicate phase reactive to trimethylsilylation was found to be anorthite. Other minerals containing silicates with a structure similar to anorthite (labradorite and augite) were also used as a Q2M6 source. This paper presents a full characterization of Q2M6 as well as information related to the residual solids from the TMS reactions. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
85.
86.
A small library of diverse N-unsubstituted 1,2,3-triazoles was prepared from the corresponding 1-sulfonyl-1,2,3-triazoles, which were treated only with MeOH at reflux temperature. This process was carried out in good yields showing high efficiency and good functional group tolerance. 相似文献
87.
Abelev BI Aggarwal MM Ahammed Z Anderson BD Arkhipkin D Averichev GS Bai Y Balewski J Barannikova O Barnby LS Baudot J Baumgart S Belaga VV Bellingeri-Laurikainen A Bellwied R Benedosso F Betts RR Bhardwaj S Bhasin A Bhati AK Bichsel H Bielcik J Bielcikova J Bland LC Blyth SL Bombara M Bonner BE Botje M Bouchet J Brandin AV Burton TP Bystersky M Cai XZ Caines H Calderón de la Barca Sánchez M Callner J Catu O Cebra D Cervantes MC Chajecki Z Chaloupka P Chattopadhyay S Chen HF Chen JH Chen JY 《Physical review letters》2008,100(23):232003
We report a new STAR measurement of the longitudinal double-spin asymmetry A(LL) for inclusive jet production at midrapidity in polarized p + p collisions at a center-of-mass energy of sqrt[s]=200 GeV. The data, which cover jet transverse momenta 5
相似文献
88.
89.
V. Moreno G. Cervantes G.B. Onoa F. Sampedro P. Santaló X. Solans M. Font-Bardía 《Polyhedron》1997,16(24):4297-4303
The effect of five derivatives of PtII, cis dichloro-(1,2-dimethyl-3-aminopyrrolidine)platinum(II), cis dichloro-(1-methyl, 2-ethyl-3-aminopyrrolidine)platinum(II), cis dichloro-(1-ethyl, 2-methyl-3-aminopyrrolidine)platinum(II), cis dichloro-(1,2-diethyl-3-aminopyrrolidine)platinum(II), and cis dichloro-(1-propyl, 2 methyl-3 aminopyrrolidine)platinum(II) on platination of DNA was studied by CD and melting temperature determination. Reactions with the nucleotides d(ApG) and d(ApA) were also followed by 1H NMR and CD, indicating binding via N(7) and formation mainly of bifunctional, in the case of d(ApG), or monofunctional adducts, in the case of d(ApA). The crystal structure of cis dichloro-(1 ethyl, 2 methyl-3 aminopyrrolidine)platinum(II) shows the analogues cisplatin structure of these active antitumour complexes. This compound is racemic. 相似文献
90.
Rosales Merlin Castillo Jéssica González Angel González Larry Molina Karely Navarro Janeth Pacheco Inés Pérez Homero 《Transition Metal Chemistry》2004,29(2):221-228
The [OsH(CO)(NCMe)2(PPh3)2]BF4 complex (1) is an efficient and regioselective precatalyst for the hydrogenation of the nitrogen-containing ring of quinoline (Q), isoquinoline (iQ), 5,6- and 7,8-benzoquinoline (BQ), and acridine (A) under mild reaction conditions (125 °C and 4 atm H2). Kinetic studies of the hydrogenation of Q and iQ to give tetrahydroquinoline (THQ) and tetrahydroisoquinoline (THiQ), respectively, lead to the rate law r = K
1
k
2/(1 + K
1[H2])[Os][H2]2, which becomes r = K
1
k
2[Os][H2]2, at low hydrogen concentrations (below 1 atm H2); the catalytically active species is of the type [OsH(CO)(L)(
1-N)(PPh3)2]BF4 [(2a): L = NCMe, N = Q; (2b): L = N = iQ]. The generic mechanisms involve a rapid and partial hydrogenation of the coordinated substrate (N) of complex (2) to yield the corresponding dihydroderivative (DHN) species [OsH(CO)(L)(
1-DHN)(PPh3)2]BF4 [(3a): L = NCMe, DHN = DHQ; (3b): L = iQ or THiQ, DHN = DHiQ], followed by the rate-determining second hydrogenation of the DHN ligand, which yield [OsH(CO)(L)(
1-THN)(PPh3)2]BF4 [(4a): L = NCMe, THN = THQ; (4b): L = iQ or THiQ, THN = THiQ]; substitution of the THN ligand by a new molecule of the respective substrate regenerates the active species and restarts the catalytic cycle. For the hydrogenation of acridine to give 9,10-dihidroacridine (acridane), the rate law was r = k
1[Os][H2]; the mechanism involves the hydrogenation of the active species [OsH(CO)(NCMe)(
1-A)(PPh3)2]BF4
(2c) to yield acridane and the unsaturated species [OsH(CO)(NCMe)(PPh3)2]BF4 as the rate-determining step. 相似文献