全文获取类型
收费全文 | 2854篇 |
免费 | 44篇 |
国内免费 | 10篇 |
专业分类
化学 | 1812篇 |
晶体学 | 23篇 |
力学 | 90篇 |
数学 | 357篇 |
物理学 | 626篇 |
出版年
2021年 | 26篇 |
2019年 | 20篇 |
2018年 | 18篇 |
2016年 | 33篇 |
2015年 | 29篇 |
2014年 | 38篇 |
2013年 | 119篇 |
2012年 | 104篇 |
2011年 | 131篇 |
2010年 | 52篇 |
2009年 | 59篇 |
2008年 | 116篇 |
2007年 | 138篇 |
2006年 | 120篇 |
2005年 | 109篇 |
2004年 | 113篇 |
2003年 | 113篇 |
2002年 | 120篇 |
2001年 | 91篇 |
2000年 | 70篇 |
1999年 | 38篇 |
1998年 | 36篇 |
1997年 | 41篇 |
1996年 | 43篇 |
1995年 | 56篇 |
1994年 | 46篇 |
1993年 | 47篇 |
1992年 | 42篇 |
1991年 | 52篇 |
1990年 | 48篇 |
1989年 | 24篇 |
1988年 | 31篇 |
1987年 | 26篇 |
1986年 | 24篇 |
1985年 | 38篇 |
1984年 | 50篇 |
1983年 | 31篇 |
1982年 | 37篇 |
1981年 | 43篇 |
1980年 | 37篇 |
1979年 | 33篇 |
1978年 | 43篇 |
1977年 | 43篇 |
1976年 | 35篇 |
1975年 | 30篇 |
1974年 | 26篇 |
1973年 | 48篇 |
1972年 | 27篇 |
1971年 | 24篇 |
1969年 | 16篇 |
排序方式: 共有2908条查询结果,搜索用时 15 毫秒
91.
Cinabro D Henderson S Liu T Saulnier M Wilson R Yamamoto H Bergfeld T Eisenstein BI Gollin G Ong B Palmer M Selen M Thaler JJ Sadoff AJ Ammar R Ball S Baringer P Bean A Besson D 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 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 《Physical review letters》1994,72(10):1406-1410
92.
J. J. Whitmore F. Persi W. S. Toothacker P. A. Elcombe J. C. Hill W. W. Neale W. D. Walker W. Kowald P. Lucas L. Voyvodic R. Ammar D. Coppage R. Davis J. Gress S. Kanekal N. Kwak J. M. Bishop N. N. Biswas N. M. Cason V. P. Kenney M. C. K. Mattingly R. C. Ruchti W. D. Shephard 《Zeitschrift fur Physik C Particles and Fields》1994,62(2):199-227
93.
Eight groups of chinchillas (N=74) were exposed to various equivalent energy [100 or 106 dB(A) sound pressure level (SPL)] noise exposure paradigms. Six groups received an interrupted, intermittent, time varying (IITV) Gaussian noise exposure that lasted 8 h/d, 5 d/week for 3 weeks. The exposures modeled an idealized workweek. At each level, three different temporal patterns of Gaussian IITV noise were used. The 100 dB(A) IITV exposure had a dB range of 90-108 dB SPL while the range of the 106 dB(A) IITV exposure was 80-115 dB SPL. Two reference groups were exposed to a uniform 100 or 106 dB(A) SPL noise, 24 h/d for 5 days. Each reference group and the three corresponding IITV groups comprised a set of equivalent energy exposures. Evoked potentials were used to estimate hearing thresholds and surface preparation histology quantified sensory cell populations. All six groups exposed to the IITV noise showed threshold toughening effects of up to 40 dB. All IITV exposures produced hearing and sensory cell loss that was similar to their respective equivalent energy reference group. These results indicate that for Gaussian noise the equal energy hypothesis for noise-induced hearing loss is an acceptable unifying principle. 相似文献
94.
95.
96.
Ajaev VS Davis SH 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》2000,61(2):1275-1284
Directional solidification of a dilute binary alloy in a Hele-Shaw cell is modeled by a long-wave nonlinear evolution equation with zero flux and contact-angle conditions at the walls. The basic steady-state solution and its linear stability criteria are found analytically, and the nonlinear system is solved numerically. Concave-down (toward the solid) interfaces under physically realistic conditions are found to be more unstable than the planar front. Weakly nonlinear analysis indicates that subcritical bifurcation is promoted, the domain of modulational instability is expanded and transition to three-dimensional patterns is delayed due to the contact-angle condition. In the strongly nonlinear regime fully three-dimensional steady-state solutions are found whose characteristic amplitude is larger than that for the two-dimensional problem. In the subcritical regime secondary bifurcation to stable solutions is promoted. 相似文献
97.
98.
Matthew C. Davis 《合成通讯》2013,43(20):3519-3528
A rapid method to prepare 1,3,5‐triaminobenzene and its derivatives is the tris‐Curtius rearrangment of 1,3,5‐benzenetricarboxylic acid. The hazards associated with the acyl azide route are minimized by using 1,2‐dichloroethane as solvent. A second method that avoids acyl azide preparation uses diphenylphosphoryl azide to yield the tricarbamate in one step. 相似文献
99.
Kanyal Supriya S. Jensen David S. Dadson Andrew E. Vanfleet Richard R. Davis Robert C. Linford Matthew R. 《平面色谱法杂志一现代薄层色谱法》2014,27(3):151-156
JPC – Journal of Planar Chromatography – Modern TLC - We describe the direct, conformal, atomic layer deposition (ALD) of silica onto carbon nanotubes (CNTs) in the microfabrication of... 相似文献
100.
Sixteen groups of chinchillas (N=140) were exposed to various equivalent energy noise paradigms at 100 dB(A) or 103 dB(A) SPL. Eleven groups received an interrupted, intermittent, and time varying (IITV) non-Gaussian exposure quantified by the kurtosis statistic. The IITV exposures, which lasted for 8 hday, 5 daysweek for 3 weeks, were designed to model some of the essential features of an industrial workweek. Five equivalent energy reference groups were exposed to either a Gaussian or non-Gaussian 5 days, 24 hday continuous noise. Evoked potentials were used to estimate hearing thresholds and surface preparations of the organ of Corti quantified the sensory cell population. For IITV exposures at an equivalent energy and kurtosis, the temporal variations in level did not alter trauma and in some cases the IITV exposures produced results similar to those found for the 5 day continuous exposures. Any increase in kurtosis at a fixed energy was accompanied by an increase in noise-induced trauma. These results suggest that the equal energy hypothesis is an acceptable approach to evaluating noise exposures for hearing conservation purposes provided that the kurtosis of the amplitude distribution is taken into consideration. Temporal variations in noise levels seem to have little effect on trauma. 相似文献