全文获取类型
收费全文 | 171篇 |
免费 | 3篇 |
专业分类
化学 | 80篇 |
力学 | 10篇 |
数学 | 30篇 |
物理学 | 28篇 |
无线电 | 26篇 |
出版年
2023年 | 1篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 14篇 |
2012年 | 5篇 |
2011年 | 12篇 |
2010年 | 9篇 |
2009年 | 3篇 |
2008年 | 6篇 |
2007年 | 6篇 |
2006年 | 7篇 |
2005年 | 7篇 |
2004年 | 7篇 |
2003年 | 3篇 |
2002年 | 1篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 6篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 6篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 6篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 1篇 |
1966年 | 2篇 |
排序方式: 共有174条查询结果,搜索用时 0 毫秒
101.
J. K. Hobbs M. J. Hill A. Keller P. J. Barham 《Journal of Polymer Science.Polymer Physics》1999,37(22):3188-3200
The temperature–concentration phase (T–c) diagrams of the uniform n-alkanes C102H206, C122H246, C162H326, and C198H398 in toluene have been determined for solution concentrations in the range 0.1 to 6% (w/w). The shorter alkanes display a “classical” behavior with the expected, strong dependence of dissolution temperature on solution concentration. The longest alkane displays a very different, “polymeric” type behavior with a concentration independent dissolution temperature (for both extended and folded chain crystals). It is argued that no current theory of polymer dissolution is able to explain this behavior. It is suggested that a locally higher concentration occurs when molecules are partially attached to a crystal either during crystallization or dissolution, and that this increased local concentration accounts for the independence of dissolution temperature on the global concentration. There are some small variations in the dissolution temperature of crystals of the same thickness grown at the same concentration, but at different temperatures. These are ascribed to differences in the stacking of the separate layers. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 3188–3200, 1999 相似文献
102.
Tiezhong Ma Campbell S.A. Smith R. Hoilien N. Boyong He Gladfelter W.L. Hobbs C. Buchanan D. Taylor C. Gribelyuk M. Tiner M. Coppel M. Jang Jung Lee 《Electron Devices, IEEE Transactions on》2001,48(10):2348-2356
The electrical performance of column IVB metal oxide thin films deposited from their respective anhydrous metal nitrate precursors show significant differences. Titanium dioxide has a high permittivity, but shows a large positive fixed charge and low inversion layer mobility. The amorphous interfacial layer is compositionally graded and contains a high concentration of Si-Ti bonds. In contrast, ZrO2 and HfO 2 form well defined oxynitride interfacial layers and a good interface with silicon with much less fixed charge. The electron inversion layer mobility for an HfO2/SiOxNy /Si stack appears comparable to that of a conventional SiO2 /Si interface 相似文献
103.
104.
Hobbs MG Knapp CJ Welsh PT Borau-Garcia J Ziegler T Roesler R 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(48):14520-14533
A series of rhodium complexes, [Rh(cod)(NHC-F(x))(OH(2))] (cod = 1,5-cyclooctadiene; NHC = N-heterocyclic carbene), incorporating anionic N-heterocyclic carbenes with 2-tert-butylmalonyl backbones and 2,6-dimethylphenyl (x = 0), 2,6-difluorophenyl (x = 4), 2,4,6-trifluorophenyl (x = 6), and pentafluorophenyl (x = 10) N,N'-substituents, respectively, has been prepared by deprotonation of the corresponding zwitterionic precursors with potassium hexamethyldisilazide, followed by immediate reaction of the resulting potassium salts with [{RhCl(cod)}(2)]. These complexes could be converted to the related carbonyl derivatives [Rh(CO)(2)(NHC-F(x))(OH(2))] by displacement of the COD ligand with CO. IR and NMR spectroscopy demonstrated that the degree of fluorination of the N-aryl substituents has a considerable influence on the σ-donating and π-accepting properties of the carbene ligands and could be effectively used to tune the electronic properties of the metal center. The carbonyl groups on the carbene ligand backbone provided a particularly sensitive probe for the assessment of the metal-to-ligand π donation. The ortho-fluorine substituents on the N-aryl groups in the carbene ligands interacted with the other ligands on rhodium, determining the conformation of the complexes and creating a pocket suitable for the coordination of water to the metal center. Computational studies were used to explain the influence of the fluorinated N-substituents on the electronic properties of the ligand and evaluate the relative contribution of the σ- and π-interactions to the ligand-metal interaction. 相似文献
105.
G. Sarri M. Borghesi C. A. Cecchetti L. Romagnani R. Jung O. Willi D. J. Hoarty R. M. Stevenson C. R.D. Brown S. F. James P. Hobbs J. Lockyear S. V. Bulanov F. Pegoraro 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,55(2):299-303
Multi-Mev proton beams generated by target normal sheath acceleration (TNSA) during the interaction of an ultra intense laser beam (I≥1019 W/cm2) with a thin metallic foil (thickness of the order of a few tens of microns) are particularly suited as a particle probe for laser plasma experiments. The proton imaging technique employs a laser-driven proton beam in a point-projection imaging scheme as a diagnostic tool for the detection of electric fields in such experiments. The proton probing technique has been applied in experiments of relevance to inertial confinement fusion (ICF) such as laser heated gasbags and laser-hohlraum experiments. The data provides direct information on the onset of laser beam filamentation and on the plasma expansion in the hohlraum’s interior, and confirms the suitability and usefulness of this technique as an ICF diagnostic. 相似文献
106.
Ding W Staines OK Hobbs GD Gorbach AV de Nobriga C Wadsworth WJ Knight JC Skryabin DV Strain MJ Sorel M De La Rue RM 《Optics letters》2012,37(4):668-670
We report frequency conversion experiments in silicon-on-insulator (SOI) directional couplers. We demonstrate that the evanescent coupling between two subwavelength SOI waveguides is strongly dispersive and significantly modifies modulational instability (MI) spectra through the coupling induced group velocity dispersion (GVD). As the separation between two 380-nm-wide silicon photonic wires decreases, the increasing dispersion of the coupling makes the GVD in the symmetric supermode more normal and suppresses the bandwidth of the MI gain observed for larger separations. 相似文献
107.
Wang Y Joshi PP Hobbs KL Johnson MB Schmidtke DW 《Langmuir : the ACS journal of surfaces and colloids》2006,22(23):9776-9783
In this study, we describe the construction of glucose biosensors based on an electrostatic layer-by-layer (LBL) technique. Gold electrodes were initially functionalized with negatively charged 11-mercaptoundecanoic acid followed by alternate immersion in solutions of a positively charged redox polymer, poly[(vinylpyridine)Os(bipyridyl)2Cl(2+/3+)], and a negatively charged enzyme, glucose oxidase (GOX), or a GOX solution containing single-walled carbon nanotubes (SWNTs). The LBL assembly of the multilayer films were characterized by UV-vis spectroscopy, ellipsometry, and cyclic voltammetry, while characterization of the single-walled nanotubes was performed with transmission electron microscopy, Raman spectroscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy. When the GOX solution contained single-walled carbon nanotubes (GOX-SWNTs), the oxidation peak currents during cyclic voltammetry increased 1.4-4.0 times, as compared to films without SWNTs. Similarly the glucose electro-oxidation current also increased (6-17 times) when SWNTs were present. By varying the number of multilayers, the sensitivity of the sensors could be controlled. 相似文献
108.
109.
J. P. Hayward C. L. Hobbs Z. W. Bell L. A. Boatner R. E. Johnson J. O. Ramey G. E. Jellison C. R. Lillard 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(2):1143-1151
Cherenkov detectors are widely used for particle identification and threshold detectors in high-energy physics. Glass Cherenkov detectors that are sensitive to beta emissions originating from neutron activation have been demonstrated recently as a potential replacement for activation foils. In this work, we set the groundwork to evaluate large Cherenkov glass detectors for sensitivity to MeV photons through first understanding the measured response of small Cherenkov glass detectors to isotopic gamma-ray sources. Counting and pulse height measurements are acquired with reflected glass Cherenkov detectors read out with a photomultiplier tube. Simulation was used to inform our understanding of the measured results. This simulation included radioactive source decay, radiation interaction, Cherenkov light generation, optical ray tracing, and photoelectron production. Implications for the use of Cherenkov glass detectors to measure low energy gamma-ray response are discussed. 相似文献
110.
J. P. Hayward Z. W. Bell L. A. Boatner C. L. Hobbs R. E. Johnson J. O. Ramey G. E. Jellison 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(2):1321-1329
Cherenkov detectors are widely used for particle identification in high-energy physics and for track imaging in astrophysics. Glass Cherenkov detectors that are sensitive to beta emissions originating from neutron activation have been demonstrated recently as a potential replacement for activation foils. In this work, we evaluate Cherenkov glass detectors for sensitivity and specificity to MeV photons through simulations using Geant4. The model has been previously compared with measurements of isotopic gamma sources. It includes Cherenkov generation, light transport, light collection, photoelectron production and time response in photomultiplier tubes. The model incorporates measured, wavelength-dependent absorption and refractive index data. Simulations are conducted for glasses the size of fabricated samples and also for the same glasses in monolithic, square-meter-size. Implications for selective detection of MeV photons are discussed. 相似文献