全文获取类型
收费全文 | 2204篇 |
免费 | 67篇 |
国内免费 | 6篇 |
专业分类
化学 | 1569篇 |
晶体学 | 36篇 |
力学 | 19篇 |
数学 | 45篇 |
物理学 | 608篇 |
出版年
2022年 | 7篇 |
2021年 | 14篇 |
2020年 | 27篇 |
2019年 | 28篇 |
2018年 | 22篇 |
2017年 | 11篇 |
2016年 | 39篇 |
2015年 | 39篇 |
2014年 | 51篇 |
2013年 | 87篇 |
2012年 | 83篇 |
2011年 | 92篇 |
2010年 | 50篇 |
2009年 | 53篇 |
2008年 | 132篇 |
2007年 | 109篇 |
2006年 | 120篇 |
2005年 | 116篇 |
2004年 | 132篇 |
2003年 | 104篇 |
2002年 | 73篇 |
2001年 | 56篇 |
2000年 | 40篇 |
1999年 | 48篇 |
1998年 | 22篇 |
1997年 | 22篇 |
1996年 | 36篇 |
1995年 | 39篇 |
1994年 | 27篇 |
1993年 | 22篇 |
1992年 | 54篇 |
1991年 | 43篇 |
1990年 | 26篇 |
1989年 | 32篇 |
1988年 | 21篇 |
1987年 | 32篇 |
1986年 | 31篇 |
1985年 | 31篇 |
1984年 | 20篇 |
1983年 | 16篇 |
1982年 | 27篇 |
1981年 | 22篇 |
1980年 | 30篇 |
1979年 | 20篇 |
1978年 | 18篇 |
1977年 | 18篇 |
1976年 | 13篇 |
1975年 | 20篇 |
1974年 | 20篇 |
1973年 | 25篇 |
排序方式: 共有2277条查询结果,搜索用时 496 毫秒
11.
12.
13.
The current status of the R & D activities is presented on electron beam processing of polymers being carried out at TRCRE. Topics included are sterilization of medical products, graft polymers for selective separation or absorbents and curing of liquid prepolymer-monomer systems. 相似文献
14.
15.
16.
G. Acbas G. B. Kim X. Chen S. Wang M. Cheon C. J. Meining H. Luo B. D. McCombe Y. Sasaki X. Liu J. K. Furdyna 《Physica E: Low-dimensional Systems and Nanostructures》2004,20(3-4):382
We have investigated the magnetic and magneto-transport properties of a systematic sequence of five InAs/Mn digital alloys grown by a combination of molecular beam epitaxy and atomic layer epitaxy. The samples consist of 30 periods of Mn fractional monolayers (ML) (0.17–0.5 ML) separated by 14 ML thick InAs spacer layers in a superlattice configuration. Four samples show n-type electrical conduction while the fifth (0.25 ML Mn) is p-type. Squid magnetization measurements performed on these samples show remnant magnetization above room temperature, which is apparently related to a second phase. 相似文献
17.
Hiroshi DanjoWataru Sasaki Takehiro MiyazakiTsuneo Imamoto 《Tetrahedron letters》2003,44(17):3467-3469
P-Chirogenic trialkylphosphonium salts were prepared from the corresponding free phosphines by treatment with a strong acid (HBF4 or HOTf). No racemization of the phosphonium salts occurred in methanol or water even at considerably high temperature. The salts were conveniently used in rhodium-catalyzed asymmetric hydrogenation of enamides. 相似文献
18.
Copper(II) is determined by non-extractive spectrophotometry as a complex of butylene dithiocarbamate formed in situ by reaction between carbon disulfide and pyrrolidine in aqueous Triton X-100 medium. This method is similar to that with butylene dithiocarbamate as starting material in the sense of simplicity, sensitivity, precision and accuracy. Pyrrolidine is the best of seven secondary amines tested in this way for copper determinations. 相似文献
19.
Current on-line solid-phase extraction methods combined with HPLC for shortening the clean-up operation are not suitable for simultaneously detecting compounds that have a wide variety of hydrophobicities. To solve these problems, we designed a new on-line sample preparation system. The system consists of an eluting pump, a mixing TEE connector, a 10-port 2-position valve and a solid-phase extraction precolumn. The eluate from the precolumn is diluted with a weak solvent from the HPLC at the TEE connection to load low hydrophobic compounds onto the analytical column. The proposed on-line sample preparation system was successfully applied to the simultaneous analysis of 21 pesticides in river water using LC/TOF-MS. In this method, the recoveries from river water samples were 67 to 126% (mean 83%), the reproducibility (CV%) was in the range from 1.1 to 11% (mean 5.6%), the calibration curve was linear in the range from 1 ppb to 500 ppb (r > 0.999) and the detection limits (S/N = 3) were in the range from 0.0034 ppb (daimuron) to 3.3 ppb (oxine-copper). 相似文献
20.
In this study, we attempted to control the timing of light-emission from bioluminescent bacteria, by changed cell numbers inoculated into medium. Luminous bacteria express bioluminescence when the number of cells reached a threshold. Inoculated cell density had an effect on the time of bioluminescence starting. Samples were prepared by varying cell density of inoculation. In the results, all the vials showed different luminescence profiles in the order of inoculated cell population. 相似文献