全文获取类型
收费全文 | 629篇 |
免费 | 6篇 |
专业分类
化学 | 319篇 |
晶体学 | 4篇 |
力学 | 33篇 |
数学 | 70篇 |
物理学 | 209篇 |
出版年
2020年 | 5篇 |
2018年 | 8篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 13篇 |
2013年 | 28篇 |
2012年 | 25篇 |
2011年 | 43篇 |
2010年 | 19篇 |
2009年 | 16篇 |
2008年 | 26篇 |
2007年 | 22篇 |
2006年 | 28篇 |
2005年 | 22篇 |
2004年 | 29篇 |
2003年 | 24篇 |
2002年 | 20篇 |
2001年 | 13篇 |
2000年 | 9篇 |
1999年 | 11篇 |
1998年 | 10篇 |
1997年 | 3篇 |
1996年 | 17篇 |
1995年 | 16篇 |
1994年 | 15篇 |
1993年 | 20篇 |
1992年 | 11篇 |
1991年 | 6篇 |
1990年 | 7篇 |
1989年 | 10篇 |
1988年 | 9篇 |
1987年 | 8篇 |
1986年 | 9篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 11篇 |
1979年 | 13篇 |
1977年 | 5篇 |
1976年 | 12篇 |
1975年 | 8篇 |
1974年 | 5篇 |
1973年 | 6篇 |
1972年 | 4篇 |
1971年 | 3篇 |
1970年 | 5篇 |
1968年 | 4篇 |
1966年 | 4篇 |
排序方式: 共有635条查询结果,搜索用时 15 毫秒
61.
Barrett PA Boix T Puche M Olson DH Jordan E Koller H Camblor MA 《Chemical communications (Cambridge, England)》2003,(17):2114-2115
The new synthetic form of microporous crystalline silica, denoted as ITQ-12, shows a high potential for the separation of propane and propene from its mixtures. 相似文献
62.
Olson ES 《The Journal of the Acoustical Society of America》2001,110(1):349-367
Pressure in turn one of the scala tympani (s.t.) was measured close to the basilar membrane (b.m.) and at additional positions as the pressure sensor approached and/or withdrew from the b.m. The s.t. pressure measured within about 100 microm of the b.m. varied rapidly in space at frequencies around the region's best frequency. Very close to the b.m. the s.t. pressure was tuned and scaled nonlinearly with sound level. The scala vestibuli (s.v.) pressure was measured at one position close to the stapes within seconds of the s.t. pressure and served primarily as a reference pressure. The driving pressure across the organ of Corti and the b.m. velocity were derived from the pressure data. Both were tuned and nonlinear. Therefore, their ratio, the specific acoustic impedance of the organ of Corti complex, was relatively untuned, and only subtly nonlinear. The impedance was inspected specifically for negative resistance (amplification) and resonance. Both were detected in some instances; taken as a whole, the current results constrain the possibilities for these qualities. 相似文献
63.
We examine the dynamics of driven classical Wigner solids interacting with quenched disorder from charged impurities. For strong disorder, the initial motion is plastic, in the form of crossing winding channels. For increasing drive, there is a reordering into a moving Wigner smectic with the electrons moving in separate 1D channels. These different dynamic phases can be related to the conduction noise and I(V) curves. For strong disorder, we show criticality in the voltage onset just above depinning. We obtain the dynamic phase diagram for driven Wigner solids and demonstrate a finite threshold of force for transverse sliding, recently observed experimentally. 相似文献
64.
Chung P Ajitanand NN Alexander JM Anderson M Best D Brady FP Case T Caskey W Cebra D Chance JL Cole B Crowe K Das A Draper JE Gilkes ML Gushue S Heffner M Hirsch AS Hjort EL Huo L Justice M Kaplan M Keane D Kintner JC Klay J Krofcheck D Lacey RA Lauret J Lisa MA Liu H Liu YM McGrath R Milosevich Z Odyniec G Olson DL Panitkin SY Pinkenburg C Porile NT Rai G Ritter HG Romero JL Scharenberg R Schroeder L Srivastava B Stone NT Symons TJ Wienold T Witt R Whitfield J Wood L Zhang WN;E Collaboration 《Physical review letters》2001,86(12):2533-2536
Directed flow measurements for Lambda hyperons are presented and compared to those for protons produced in the same Au+Au collisions (2A, 4A, and 6A GeV; b<5-6 fm). The measurements indicate that Lambda hyperons flow consistently in the same direction but with smaller magnitudes. A strong positive flow [for Lambdas] has been predicted in calculations which include the influence of the Lambda-nucleon potential. The experimental flow ratio Lambda/p is in qualitative agreement with expectations (approximately 2/3) from the quark counting rule at 2A GeV but is found to decrease with increasing beam energy. 相似文献
65.
Static and dynamic coupling transitions of vortex lattices in disordered anisotropic superconductors 总被引:1,自引:0,他引:1
We use three-dimensional molecular dynamics simulations of magnetically interacting pancake vortices to study vortex matter in disordered, highly anisotropic materials such as BSCCO. We observe a sharp 3D-2D transition from vortex lines to decoupled pancakes as a function of relative interlayer coupling strength, with an accompanying large increase in the critical current reminiscent of a second peak effect. We find that decoupled pancakes, when driven, simultaneously recouple and order into a crystalline-like state at high drives. We construct a dynamic phase diagram and show that the dynamic recoupling transition is associated with a double peak in dV/dI. 相似文献
66.
Johnson PM Olson DA Pankratz S Nguyen T Goodby J Hird M Huang CC 《Physical review letters》2000,84(21):4870-4873
The unit cell structures of two ferrielectric liquid-crystal phases are determined from ellipsometric studies of freestanding films in a nondistorting rotatable electric field. A highly biaxial mode with out-of-plane distortions describes all of the data from two different compounds. Qualitative and quantitative features of the data rule out alternate models. We also present a detailed explanation for apparent inconsistencies between previous resonant x-ray and optical experiments. 相似文献
67.
R. R. Mhaskar S. E. Olson G. Raithel 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(2):221-227
A method of imaging distributions of cold atoms under the presence of large
trapping-field-induced level shifts is investigated. By utilizing a probe
laser tuned to an open transition, the fluorescence yield per atom is
largely fixed throughout the trap volume, independent of the trapping
field. This enables a reliable conversion of fluorescence images into
atomic-density profiles. The method is applied to measure distributions of
87Rb atoms in a high-gradient (2.7 kG/cm) magnetic atom guide. We
characterize the parameters for which the open-channel imaging method
performs best. Results of quantum Monte Carlo simulations verify the
underlying assumptions of the method. 相似文献
68.
A. T. Kwan M. Yu. Efremov E. A. Olson F. Schiettekatte M. Zhang P. H. Geil L. H. Allen 《Journal of Polymer Science.Polymer Physics》2001,39(11):1237-1245
We used thin‐film differential scanning calorimetry to investigate the melting of isolated polyethylene single crystals with lamellar thicknesses of 12 ± 1 nm. We observed the melting of as few as 25 crystals. Over a wide number of crystals (25–2000 crystals), the heat of fusion was 40% larger than the bulk value. The melting temperature of the isolated single crystals was 123 ± 2 °C, 9 °C lower than that of the bulk material. We also measured the heat of fusion of quenched crystals (±15%) over a wide range of heating rates (20,000–100,000 K/s). Annealing the quenched crystals resulted in shifts in the endotherm peak by as much as 15 °C. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 1237–1245, 2001 相似文献
69.
70.
Gordon L. Olson 《Journal of computational physics》2009,228(8):3072-3083
Using polynomials to represent the angular variation of the radiation intensity is usually referred to as the PN or spherical harmonics method. For infinite order, the representation is an exact solution of the radiation transport solution. For finite N, in some physical situations there are oscillations in the solution that can make the radiation energy density be negative. For small N, the oscillations may be large enough to force the material temperature to numerically have non-physical negative values. The second-order time evolution algorithm presented here allows for more accurate solutions with larger time steps; however, it also can resolve the negativities that first-order time solutions smear out. Therefore, artificial scattering is studied to see how it can be used to decrease the oscillations in low-order solutions and prevent negativities. Small amounts of arbitrary, non-physical scattering can significantly improve the accuracy of the solution to test problems. Flux-limited diffusion solutions can also be improved by including artificial scattering. One- and two-dimensional test results are presented. 相似文献