全文获取类型
收费全文 | 786篇 |
免费 | 67篇 |
专业分类
化学 | 579篇 |
晶体学 | 4篇 |
力学 | 21篇 |
数学 | 80篇 |
物理学 | 169篇 |
出版年
2023年 | 6篇 |
2022年 | 21篇 |
2021年 | 20篇 |
2020年 | 24篇 |
2019年 | 26篇 |
2018年 | 16篇 |
2017年 | 13篇 |
2016年 | 44篇 |
2015年 | 26篇 |
2014年 | 24篇 |
2013年 | 34篇 |
2012年 | 54篇 |
2011年 | 72篇 |
2010年 | 32篇 |
2009年 | 25篇 |
2008年 | 40篇 |
2007年 | 41篇 |
2006年 | 35篇 |
2005年 | 35篇 |
2004年 | 32篇 |
2003年 | 24篇 |
2002年 | 17篇 |
2001年 | 4篇 |
2000年 | 8篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 15篇 |
1996年 | 8篇 |
1995年 | 6篇 |
1994年 | 15篇 |
1993年 | 8篇 |
1992年 | 6篇 |
1991年 | 12篇 |
1990年 | 6篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1986年 | 8篇 |
1985年 | 4篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1973年 | 4篇 |
1968年 | 4篇 |
1967年 | 5篇 |
1966年 | 3篇 |
1960年 | 4篇 |
1958年 | 4篇 |
排序方式: 共有853条查询结果,搜索用时 31 毫秒
11.
A new spectrophotometric method for the determination of traces of tin in steel is presented. The tin is isolated by an acid sulfide separation and a double carbamate-chloroform extraction and then determined by a phenylfluorone method in which the selectivity is increased by the use of peroxide and oxalate as masking agents and the sensitivity is increased by extracting the colored tin compound into a small volume of MIBK for the spectrophotometric analysis. 相似文献
12.
A total internal reflection (TIR)-based biochip utilizing a polymer-filled cavity with a micromirror sidewall has been designed and fabricated. The implementation of the micromirror sidewall cavity facilitates precise alignment of the excitation light beam into the system. The incident angle of illumination can be easily modified by selecting polymers of different indices of refraction while optical losses are minimized. The design enables the hybrid, vertical integration of a laser diode and a CCD camera, resulting in a compact optical system. Brownian motion of fluorescent microspheres and real-time photobleaching of rhodamine 6G molecules is demonstrated. The proposed TIR-based chip simplifies current TIR optical configurations and could potentially be used as an optical-microfluidic platform for an integrated lab-on-a-chip microsystem. 相似文献
13.
14.
15.
16.
W. D. Wu A. Keren L. P. Le G. M. Luke B. J. Sternlieb Y. J. Uemura D. C. Johnston B. K. Cho P. Gehring 《Hyperfine Interactions》1994,86(1):615-621
Muon spin relaxation (SR) studies have been performed in the normal spinel LiTi2O4 and the A-15 superconductor V3Si to measure the magnetic penetration depth . The relaxation rate(T) 1/2 in field-cooled measurements shows a sharp increase belowT
c
followed by saturation at low temperatures in both systems. This feature implies an isotropic energy gap without anomalous zeros, and most likelys-wave pairing. The low temperature penetration depth (T 0) is determined to be 2100Å for LiTi2O4 and 1300Å for V3Si respectively. Assuming a clean limit relation –2 n
s
/m
*, we derive the Fermi temperatureT
F
n
s/
2/3
m
* from the relaxation rate and the Sommerfeld constant asT
F
3/4–1/4. Unlike conventional superconductors, both LiTi2O4 and V3Si have a large ratio ofT
c
/T
F
0.01, only slightly smaller than those ratios in more exotic superconductors.We thank C. Ballard and K. Hoyle for technical assistance. Work at Columbia University is supported by NSF Grant No. DMR-89-13784 and Packard Foundation (YJU). Ames Laboratory is operated for the U. S. Department of Energy by Iowa State University under Contract No. W-7405-Eng-82. Work at Ames was supported by the Director for Energy Research, Office of Basic Energy Sciences. 相似文献
17.
18.
19.
20.