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排序方式: 共有143条查询结果,搜索用时 15 毫秒
11.
12.
Schumm BA Koetke DS Adolphsen CE Alexander JP Averill D Barish BC Barklow T Barnett BA Blockus D Boyarski A Brabson B Breakstone A Bulos F Burchat PR Burke DL Cence RJ Chapman J Chmeissani M Cords D Coupal DP Dauncey P DeStaebler HC Dorfan JM Drell PS Drewer DC Durrett D Elia R Feldman GJ Field RC Ford WT Fordham C Frey R Fujino D Gan KK Gero E Gidal G Glanzman T Goldhaber G Gomez Cadenas JJ Gratta G Hanson G Harr R Harral B Harris FA Hayes K Hearty C Heusch CA Hildreth MD Himel T Hinshaw DA 《Physical review D: Particles and fields》1992,46(1):453-456
13.
Ralph P. Cooney Martin W. Howard Merrick R. Mahoney Terrence P. Mernagh 《Chemical physics letters》1981,79(3):459-464
A mechanism is proposed for surface-enhanced Raman scattering for pyridine which explains the enhancement, the anodizalion “activation”, the significance of silver, the photographitization of coordinated pyridine and formate, the participation of surface roughness, and the irreversibly held yet liquid-like nature of surface pyridine. 相似文献
14.
Background
Growth hormone (GH) plays an incompletely understood role in the development of the central nervous system (CNS). In this study, we use transgenic mice expressing a growth hormone antagonist (GHA) to explore the role of GH in regulating postnatal brain, spinal cord and body growth into adulthood. The GHA transgene encodes a protein that inhibits the binding of GH to its receptor, specifically antagonizing the trophic effects of endogenous GH. 相似文献15.
Nagarajan K Joshi HK Chaudhury PK Pal K Cooney JJ Enemark JH Sarkar S 《Inorganic chemistry》2004,43(15):4532-4533
Synthesis of [PPh4]2[Mo(SPh)2(S2C2(CN)2)2] (2) from [PPh4]2[MoO(S2C2(CN)2)2] (1) has been achieved to mimic the postulated [Mo(S)6] core of polysulfide reductase with two thiolates and two bis(ene-dithiolate) ligands. Compound 2 reacts with polysulfide to yield H2S, modeling the function of polysulfide reductase. The facile conversion of 2 back to 1 in moist solvent suggests that the interconversion of the [MoIV = O] and [MoIV - X] (X = O-Ser, S-Cys, Se-Cys) moieties might occur in the DMSO reductase class of enzymes under appropriate hydrophobic/hydrophilic conditions. 相似文献
16.
Diastereospecific ion pairs consisting of isospecific transition-metal cations and syndiospecific main-group anions promote what is termed amphicatalytic polymerization of MMA, producing PMMA with isotactic-b-syndiotactic stereomultiblock microstructures. 相似文献
17.
Gomez L Slutzky C Ferron J de La Figuera J Camarero J Vazquez De Parga AL de Miguel JJ Miranda R 《Physical review letters》2000,84(19):4397-4400
Generic computer simulations using empiric interatomic potentials suggest a new, collective mechanism that could be responsible for mixing at heteroepitaxial interfaces. Even if single adsorbate atoms diffuse by hopping on the substrate surface and do not mix at the terraces, two-dimensional islands formed by nucleation may become unstable above a certain critical size and explode upwards forming clusters of several atomic layers. This process is accompanied by strong distortions of the underlying atomic layers, and on soft materials it can result in surface etching and incorporation of substrate atoms into the islands. 相似文献
18.
Ghaemi M.S. Cooney J. Tao J. Lim W.-B. Lonngren K.E. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1990,18(2):249-251
The deposition of an insulating layer upon an aluminum plate in an argon plasma is described. The process is effected in a low-power DC discharge to which a small amount of sulfur hexafluoride (SF6) has been added, causing the formation of anode spots at sharp metallic surfaces. The insulator is deposited in the region beneath the spot 相似文献
19.
Infrared spectra of CO-treated platinum hydrosols subsequently treated with acetylene, hydrogen, and oxygen reveal that v(CO)ads decreases from 2070 cm−1 with increasing gas-treatment time. This has been attributed to a reduction in the coverage of adsorbed CO. In Pt sol/CO/C2H2 systems, v(CO)ads decreases to a limiting value of ca. 2060 cm−1 after exposure to acetylene. In the Pt sol/CO/H2 systems, v(CO)ads decreases to ca. 2050 cm−1 after exposure to hydrogen gas. The lower frequency in the Pt sol/CO/H2 system has been attributed to CO adsorption on more active metal sites formed from the reduction of surface platinum oxides. Exposure of the CO-treated platinum hydrosols to O2 gas was found to cause the eventual disappearance of the v(CO)ads band in infrared spectra, which was attributed to oxidation of adsorbed CO to CO2 by weakly bound surface layers of platinum oxides formed by the oxygen treatment. 相似文献
20.
Jean-Ruel H Cooney RR Gao M Lu C Kochman MA Morrison CA Miller RJ 《The journal of physical chemistry. A》2011,115(45):13158-13168
The cyclization reaction of the photochromic diarylethene derivative 1,2-bis(2,4-dimethyl-5-phenyl-3-thienyl)perfluorocyclopentene was studied in its single crystal phase with femtosecond transient absorption spectroscopy. The transient absorption measurements were performed with a robust acquisition scheme that explicitly exploits the photoreversibility of the molecular system and monitors the reversibility conditions. The crystalline system demonstrated 3 × 10(4) repeatable cycles before significant degradation was observed. Immediately following photoexcitation, the excited state absorption associated with the open-ring conformation undergoes a large spectral shift with a time constant of approximately 200 fs. Following this evolution on the excited state potential energy surface, the ring closure occurs with a time constant of 5.3 ps, which is significantly slower than previously reported measurements for similar derivatives in the solution phase. Time resolved electron diffraction studies were used to further demonstrate the assignment of the transient absorption dynamics to the ring closing reaction. The mechanistic details of the ring closing are discussed in the context of prior computational work along with a vibrational mode analysis using density functional theory to give some insight into the primary motions involved in the ring closing reaction. 相似文献