全文获取类型
收费全文 | 4099篇 |
免费 | 166篇 |
国内免费 | 18篇 |
专业分类
化学 | 2832篇 |
晶体学 | 41篇 |
力学 | 96篇 |
数学 | 349篇 |
物理学 | 965篇 |
出版年
2024年 | 5篇 |
2023年 | 21篇 |
2022年 | 71篇 |
2021年 | 93篇 |
2020年 | 79篇 |
2019年 | 70篇 |
2018年 | 59篇 |
2017年 | 46篇 |
2016年 | 122篇 |
2015年 | 114篇 |
2014年 | 142篇 |
2013年 | 241篇 |
2012年 | 318篇 |
2011年 | 348篇 |
2010年 | 182篇 |
2009年 | 171篇 |
2008年 | 266篇 |
2007年 | 246篇 |
2006年 | 225篇 |
2005年 | 219篇 |
2004年 | 171篇 |
2003年 | 152篇 |
2002年 | 138篇 |
2001年 | 89篇 |
2000年 | 93篇 |
1999年 | 76篇 |
1998年 | 59篇 |
1997年 | 36篇 |
1996年 | 49篇 |
1995年 | 47篇 |
1994年 | 50篇 |
1993年 | 47篇 |
1992年 | 33篇 |
1991年 | 21篇 |
1990年 | 29篇 |
1989年 | 24篇 |
1988年 | 8篇 |
1987年 | 10篇 |
1986年 | 15篇 |
1985年 | 15篇 |
1984年 | 10篇 |
1983年 | 8篇 |
1982年 | 12篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1975年 | 4篇 |
1974年 | 7篇 |
1973年 | 4篇 |
排序方式: 共有4283条查询结果,搜索用时 15 毫秒
31.
M.C. Robinson D.J. Morris P.D. Hayenga J.H. Cho C.D. Richards R.F. Richards D.F. Bahr 《Applied Physics A: Materials Science & Processing》2006,85(2):135-140
Piezoelectric membranes have been fabricated that incorporate a gold bottom electrode with an adhesion layer of titanium–tungsten (10:90 wt. %). For solution-deposited acetic acid based lead zirconate titanate (HoAc-PZT) with a Zr:Ti ratio of 40:60, the film’s average piezoelectric coefficient, e31, is -5.31 C/m2, with a dielectric constant of 814 at 200 Hz, which is similar to values for platinum bottom electrodes. The PZT structure remains columnar on both types of bottom electrodes. Initial fabrication attempts resulted in cracking that initiated in the PZT layer of the structure. X-ray photoelectron spectroscopy was utilized to establish how processing affects diffusion throughout the composite membrane structure. Crack-free membranes were fabricated and tested. This paper discusses the performance properties and piezoelectric fatigue results for these membranes. PACS 77.84.-s; 77.84.Lf 相似文献
32.
Anisha Gokarna Yong Hwan Kim Yong-Hoon Cho Min Su Lee In Cheol Kang Hyun Kyu Park Min Gon Kim Bong Hyun Chung 《Optical Review》2006,13(4):288-291
We demonstrate the fluorescence mapping of protein microarrays by the technique of scanning near-field optical microscopy
(SNOM) and confocal microscopy. Micron sized spots (300 μm) of human Immunoglobulin G (hIgG) protein with and without a Cy3
dye labeling have been fabricated on glass substrates by an immobilization method which makes use of calixcrown derivatives
termed Prolinker. We have also tried to probe into the well-known “doughnut effect” observed in fluorescence images of proteins
using the SNOM technique. The topographic and fluorescence SNOM images revealed that the number of proteins at the boundary
of the spot were more than at the center in the case of the microarray spot which showed brighter luminescence at the edge
than at the center in the confocal image. 相似文献
33.
34.
35.
The pressure dependence of the direct and indirect bandgap of epitaxial In0.52Al0.48As on InP(001) substrate has been measured using photoluminescence up to 92 kbar hydrostatic pressure. The bandgap changes
from Γ toX at an applied pressure of ∼ 43 kbar. Hydrostatic deformation potentials for both the Γ andX bandgaps are deduced, after correcting for the elastic constant (bulk modulus) mismatch between the epilayer and the substrate.
For the epilayer we obtain
and+(2.81±0.15)eV for the Γ andX bandgaps respectively. From the pressure dependence of the normalized Γ-bandgap photoluminescence intensity a Γ-X lifetime ratio, (τΓ/τ
X
), of 4.1×10−3 is deduced. 相似文献
36.
37.
38.
Fukuji Higashi Chong Su Cho Hideo Kakinoki Osao Sumita 《Journal of polymer science. Part A, Polymer chemistry》1977,15(10):2303-2309
Semiconducting organic polymer was obtained by the modification of polyacrylamide (PAAm)–Cu++ chelate with iodine in acetone. Favorable conditions for preparing the chelate effective for the conduction were investigated. Surface resistivities were affected by the amounts of cupric salts and iodine, satisfactory results being given by about 25 wt % of the salts based on PAAm and more than 1 wt % of iodine on the chelate. The conductivity was also varied with the degree of neutralization of the chelate in solution, and optimal values were obtained by addition of about an equimolar amount of potassium hydroxide to cupric salts. Effective structures of the polymer chelate in solution were assumed on the basis of the visible and the NMR spectra and potentiometric titration. 相似文献
39.
S. Y. Cho O. D. Awh Y. J. Chung Y. S. Chung 《Journal of Radioanalytical and Nuclear Chemistry》1997,217(1):107-109
A nondestructive instrumental neutron activation technique was used to analyze human hair samples collected from people living in metropolitan and rural areas in Korea. Samples were also collected from factory workers and cancer patients. Hair from metropolitan area residents contain higher concentrations of Ca, Mg, Zn, Cu, Na, Br, Mn, I and S than rural area residents. Concentrations of I and S from cancer patients, Mg, Zn, Al, Na, Mn and As from glassware workers were relatively higher. The results show that the trace element concentrations of the hair are possibly related to the trace element concentrations in the body. 相似文献
40.
Oxychelerythrine, benzo[c]phenanthridine alkaloid, was synthesized from easily available starting toluamide 5 and benzonitrile 6 using toluamide-benzonitrile cycloaddition reaction in 6 steps. 相似文献