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排序方式: 共有207条查询结果,搜索用时 500 毫秒
11.
Alam MS Kim IJ Nemati B O'Neill JJ Severini H Sun CR Zoeller MM Crawford G Daubenmier CM Fulton R Fujino D Gan KK Honscheid K Kagan H Kass R Lee J Malchow R Morrow F Skovpen Y Sung M White C Butler F Fu X Kalbfleisch G Ross WR Skubic P Snow J Wang PL Wood M Brown DN Fast J McIlwain RL Miao T Miller DH Modesitt M Payne D Shibata EI Shipsey IP Wang PN Battle M Ernst J Kwon Y Roberts S Thorndike EH Wang CH Dominick J Lambrecht M Sanghera S Shelkov V Skwarnicki T Stroynowski R Volobouev I Wei G 《Physical review D: Particles and fields》1994,50(1):43-68
12.
Crawford G Daubenmier CM Fulton R Fujino D Gan KK Honscheid K Kagan H Kass R Lee J Malchow R Morrow F Skovpen Y Sung M White C Whitmore J Wilson P Butler F Fu X Kalbfleisch G Lambrecht M Ross WR Skubic P Snow J Wang PL Wood M Bortoletto D Brown DN Fast J McIlwain RL Miao T Miller DH Modesitt M Schaffner SF Shibata EI Shipsey IP Wang PN Battle M Ernst J Kroha H Roberts S Sparks K Thorndike EH Wang CH Dominick J Sanghera S Skwarnicki T Stoynowski R Artuso M He D Goldberg M Horwitz N Kennett R 《Physical review letters》1993,71(20):3259-3262
13.
Cinabro D Henderson S Kinoshita K Liu T Saulnier M Wilson R Yamamoto H Sadoff AJ Ammar R Ball S Baringer P Coppage D Copty N Davis R Hancock N Kelly M Kwak N Lam H Kubota Y Lattery M Nelson JK Patton S Perticone D Poling R Savinov V Schrenk S Wang R Alam MS Kim IJ Nemati B O'Neill JJ Romero V Severini H Sun CR Zoeller MM Crawford G Fulton R Fujino D Gan KK Kagan H Kass R Lee J Malchow R Morrow F Skovpen Y Sung M White C Whitmore J Wilson P Butler F Fu X Kalbfleisch G Lambrecht M Ross WR 《Physical review letters》1993,70(24):3700-3704
14.
J Holinej H Y Ando J W Snow 《Journal of chemical information and computer sciences》1989,29(4):233-236
Buffer changes and certain drugs cause temperature shifts, amplitude changes, and transition broadening in the differential scanning calorimetric (DSC) analysis of erythrocyte membranes. However, it has been difficult to interpret and quantitate these shifts and changes because the scans are composed of multiple overlapping transitions and because more than one transition may be simultaneously affected. An empirical approach has been developed by using Gaussian modeling to resolve these calorimetric transitions. Data analysis was carried out on a microcomputer using a nonlinear regression program (PCNONLIN) to fit the data scans. These results show that changes in the calorimetric scans of erythrocyte membranes due to alterations in the buffer environment, such as pH and osmolarity, can be resolved by fitting the data scans with the proposed mathematical model and optimizing the resolution parameters with PCNONLIN. In addition, resolution uncovered hidden characteristics that may not have been readily evident. Under certain conditions, for example, apparent transition shifts were shown to actually be amplitude changes and transition broadening. Determination of the limitations and validity of this method was accomplished with simulation studies. This technique offers a simple means for fitting overlapping DSC transitions by use of a commercially available nonlinear regression program that can be run on a microcomputer. 相似文献
15.
Mark E. Snow 《Journal of computational chemistry》1992,13(5):579-584
Protein-folding potentials, designed with the explicit goal that the global energy minimum correspond to crystallographically observed conformations of protein molecules, may offer great promise toward calculating native protein structures. Achieving this promise, however, depends on finding an effective means of dealing with the multiple-minimum problem inherent in such potentials. In this study, a protein-folding-potential test system has been developed that exhibits the properties of general protein-folding potentials yet has a unique well-defined global energy minimum corresponding to the crystallographically determined conformation of the test molecule. A simulated-annealing algorithm is developed that locates the global minimum of this potential in four of eight test runs from random starting conformations. Exploration of the energy-conformation surface of the potential indicates that it contains the numerous local minima typical of protein-folding potentials and that the global minimum is not easily located by conventional minimization procedures. When the annealing algorithm is applied to a previously developed actual folding potential to analyze the conformation of avian pancreatic polypeptide, a new conformer is located that is lower in energy than any conformer located in previous studies using a variety of minimization techniques. 相似文献
16.
Michael I. Bruce Ernst Horn Janis G. Matisons Michael R. Snow 《Journal of organometallic chemistry》1985,286(2):271-287
The reactions of Os3(μ-H)2(CO)10 with a series of Group IB metal acetylide-tertiary phosphine complexes are described. Whereas the compounds M(C2C6F5)(PPh3) (M = Cu, Ag, Au) afforded the complexes MOs3(μ-CHCHC6F5)(CO)10(PPh3) cleanly and in high yield, complex mixtures of products were obtained from reactions of the analogous phenylacetylides. The complexes MOs3(μ-CHCHPh)(CO)10(PPh3), MOs3(μ-CHCHPh)(CO)9(PPh3)2 and MOs3(μ-H)(CO)10(PPh3) (of known structure), and MOs3(μ-CHCHPh)(CO)9(PPh3)2 and HMOs3(CHCPh)(CO)8 (of unknown structure) were characterised; Au(C2Ph)(PMe3) afforded similar derivatives. The reactions proceed by oxidative-addition and hydrogen migration steps; MP bond cleavage reactions also occur to a small extent. The molecular structures of AuOs3(μ-CHCHC6R5)(CO)10(PPh3) (R = F or H) were determined by X-ray analyses. For R = F, crystals are triclinic, space group P with a 9.081(2), b 13.291(2), c 17.419(2) Å, α 84.49(1), β 76.20(2), γ 75.81(2)° and Z = 2; 4622 observed data [I > 2.5σ(I)] were refined to R = 0.027, RW = 0.031. For R = H, crystals are triclinic, space group P, with a 9.403(4), b 13.448(3), c 13.774(4) Å, α 83.34(2), β 88.66(3), γ 70.21(3)°, and Z = 2; 4405 observed data [I > 2.5σ(I)] were refined to R = 0.030, RW = 0.033. The two molecules differ in the orientation of the Ph rings of the PPh3 groups, but are otherwise similar to Os3(μ-H)(μ-CHCHBut)(CO)10 with the μ-H ligand replaced by the isolobal μ-Au(PPh3) group. 相似文献
17.
Alam MS Kim IJ Nemati B O'Neill JJ Romero V Severini H Sun CR Wang P Zoeller MM Crawford G Fulton R Gan KK Kagan H Kass R Lee J Malchow R Morrow F Sung M White C Whitmore J Wilson P Butler F Fu X Kalbfleisch G Lambrecht M Skubic P Snow J Bortoletto D Brown DN Dominick J McIlwain RL Miao T Miller DH Modesitt M Schaffner SF Shibata EI Shipsey IP Battle M Ernst J Kroha H Roberts S Sparks K Thorndike EH Wang C Artuso M Goldberg M Haupt T Horwitz N Kennett R Moneti GC Playfer S Rozen Y Rubin P 《Physical review D: Particles and fields》1992,46(11):4822-4827
18.
The richly varied reactivity of the aldehyde group frequently imparts pivotal importance to this functionality in organic synthesis. This fact has resulted in the development of several methods for the elaboration of this structural unit from a variety of precursors.2 The report delineates the feasibility of two new couplementary approaches which proceed under mild conditions and demonstrate the utility of “halothiation” as applied to the oxidation of primary halides and terminal olefins. We were led to investigate this approach as a direct consequence of our interest in the Ramberg-Bäcklund rearrangement3 where the preliminary step often involves α-chlorination of the sulfide substrate.4 Halothiation is defined by us as a three-step transformation involving introduction of an ArS moiety, directed α-chlorination of the resulting sulfide, and hydrolysis. In principle, of course, the ArSCH2-unit is uniquely an aldehyde synthon and attention is therefore focused specifically on it at this time. 相似文献
19.
Arthur W. Snow 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(10):1429-1441
Butadiyne was thermally polymerized from the vapor phase onto substrate polyethylene, poly(vinylidene fluoride), polytetrafluoro-ethylene, and fluorinated ethylene propylene films at 20°C. The reaction is characterized as an initial absorption of monomer into the film followed by polymerization in the condensed state. A postpolymerization thermal reaction of the polybutadiyne pendant ethynyl groups was conducted over a 120 to 470°C temperature range with a subsequent surface electrical resistivity decrease to 7 × 1011 ohm/square. The reaction of the pendant acetylenic groups was monitored by DSC and IR spectroscopy and found to be more complex than an intramolecular conversion of an acetylenic polyene to a polyacene structure. 相似文献
20.
We report what we believe to be the first rigorous numerical solution of the two-dimensional Maxwell equations for optical propagation within, and scattering by, a random medium of macroscopic dimensions. Our solution is based on the pseudospectral time-domain technique, which provides essentially exact results for electromagnetic field spatial modes sampled at the Nyquist rate or better. The results point toward the emerging feasibility of direct, exact Maxwell equations modeling of light propagation through many millimeters of biological tissues. More generally, our results have a wider implication: Namely, the study of electromagnetic wave propagation within random media is moving toward exact rather than approximate solutions of Maxwell's equations. 相似文献