全文获取类型
收费全文 | 2060篇 |
免费 | 136篇 |
国内免费 | 11篇 |
专业分类
化学 | 1346篇 |
晶体学 | 8篇 |
力学 | 45篇 |
数学 | 112篇 |
物理学 | 221篇 |
无线电 | 475篇 |
出版年
2024年 | 3篇 |
2023年 | 15篇 |
2022年 | 24篇 |
2021年 | 49篇 |
2020年 | 60篇 |
2019年 | 58篇 |
2018年 | 21篇 |
2017年 | 40篇 |
2016年 | 100篇 |
2015年 | 71篇 |
2014年 | 114篇 |
2013年 | 156篇 |
2012年 | 166篇 |
2011年 | 179篇 |
2010年 | 98篇 |
2009年 | 101篇 |
2008年 | 149篇 |
2007年 | 123篇 |
2006年 | 96篇 |
2005年 | 95篇 |
2004年 | 78篇 |
2003年 | 80篇 |
2002年 | 93篇 |
2001年 | 27篇 |
2000年 | 33篇 |
1999年 | 25篇 |
1998年 | 19篇 |
1997年 | 21篇 |
1996年 | 19篇 |
1995年 | 9篇 |
1994年 | 12篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1974年 | 3篇 |
1971年 | 4篇 |
1970年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有2207条查询结果,搜索用时 17 毫秒
11.
Chang Hyeong Lee Kyung Duk Park Bongsoo Jang 《Journal of mathematical chemistry》2013,51(7):1945-1960
In this paper, we present the multistage homotopy perturbation method for finding the solution of the chemical kinetics with nonlinear reactions. We develop a general scheme for finding the analytic solution of chemical reaction networks and apply it to motivating chemical examples such as the enzyme kinetics model and the Brusselator model. We illustrate the numerical result for the models and show the accuracy of the method. 相似文献
12.
Dr. Chi Kyung Kim Taeho Kim In‐Young Choi Min Soh Dr. Dohoung Kim Young‐Ju Kim Dr. Hyunduk Jang Hye‐Sung Yang Dr. Jun Yup Kim Dr. Hong‐Kyun Park Dr. Seung Pyo Park Sangseung Park Dr. Taekyung Yu Prof. Byung‐Woo Yoon Prof. Seung‐Hoon Lee Prof. Taeghwan Hyeon 《Angewandte Chemie (International ed. in English)》2012,51(44):11172-11172
13.
Cyclic β‐bromo‐α,β‐unsaturated carboxylic acids are carbonylatively cyclized with primary amines under carbon monoxide pressure in MeCN in the presence of a catalytic amount of PdCl2(PPh3)2 to give N‐alkylmaleimides. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
14.
A liquid chromatographic chiral stationary phase based on (+)‐(18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid was applied to the resolution of 15 analytes, including racemic rasagiline, a chiral drug for the treatment of Parkinson's disease, and its analogues. The composition of mobile phase was optimized to be ethanol/acetonitrile/acetic acid/triethylamine (80:20:0.2:0.3, v/v/v/v) by evaluating the chromatographic results for the resolution of five selected analytes under various mobile phase conditions. Under the optimized mobile phase conditions, racemic rasagiline was resolved quite well with a separation factor of 1.48 and resolution of 2.71 and its 14 analogues were also resolved reasonably well with separation factors of 1.06–1.54 and resolutions of 0.54–2.11. Among 15 analytes, racemic rasagiline was resolved best except for just one analyte. The analyte structure–enantioselectivity relationship indicated that racemic rasagiline has the most appropriate structural characteristics for resolution on the chiral stationary phase. 相似文献
15.
Dong‐Won Lee Won‐Ju Cho Jun‐Kwang Song Oh‐Yun Kwon Won‐Hee Lee Chi‐Hong Park Kyung‐Eun Park Heesoo Lee Yong‐Nam Kim 《Progress in Photovoltaics: Research and Applications》2015,23(7):829-837
High‐temperature‐induced and humidity‐induced degradation behaviors were investigated through the failure analysis of encapsulated Cu(In,Ga)Se2 (CIGS) modules and non‐encapsulated CIGS cells. After being exposed to high temperature (85 °C) for 1000 h, the efficiency loss of CIGS modules and the resistivities of the aluminum‐doped zinc oxide (AZO) layer, CIGS layer, and Mo layer were slightly increased. After damp heat (DH) testing (85 °C/85% RH), the efficiency of some modules decreased significantly accompanied by discoloration, and in these areas, the resistivity of the AZO layers increased markedly. The causes of degradation of CIGS cells after high temperature and DH tests were suggested through X‐ray photoelectron spectroscopy analysis. The high‐temperature‐induced degradation behaviors were revealed to be increases in series resistance of the CIGS cells, due to the adsorption of oxygen on the AZO, CIGS, and Mo layers. The degradation behavior after DH (85 °C/85% RH) exposure was caused by the adsorption of oxygen, as well as the generation of Zn(OH)2 due to water molecules. In particular, the humidity‐induced degradation behavior in discolored CIGS modules was ascribed to the generation of Zn(OH)2 and carboxylic acids in the AZO layer, due to a chemical reaction between the AZO, ethylene‐vinyl acetate copolymer, and water. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
16.
17.
Shantaram Kothavale Kyung Hyung Lee Prof. Jun Yeob Lee 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(4):845-852
Two efficient thermally activated delayed fluorescent (TADF) emitters were developed by utilizing CN-modified imidazopyridine as an acceptor unit. The CN-modified imidazopyridine acceptor was combined with either an acridine donor or a phenoxazine donor through a phenyl linker to produce two TADF emitters, Ac-CNImPy and PXZ-CNImPy. The acridine-based Ac-CNImPy emitter exhibited sky-blue emission with a CIE coordinate of (0.18, 0.38), whereas the phenoxazine-donor-based PXZ-CNImPy showed greenish-yellow emission with a CIE coordinate of (0.32, 0.58). A high photoluminescence quantum yield of 80 % was observed for the PXZ-CNImPy emitter compared with 40 % for the Ac-CNImPy emitter. Organic light-emitting diodes based on the PXZ-CNImPy emitter demonstrated high external quantum efficiency of 17.0 %. Hence, the CN-modified imidazopyridine unit can be considered as a useful electron acceptor for the future design of highly efficient TADF emitters. 相似文献
18.
Kyung Hoon Han 《Journal of Functional Analysis》2011,261(4):999-386
We prove that an operator system S is nuclear in the category of operator systems if and only if there exist nets of unital completely positive maps φλ:S→Mnλ and ψλ:Mnλ→S such that ψλ°φλ converges to idS in the point-norm topology. Our proof is independent of the Choi-Effros-Kirchberg characterization of nuclear C?-algebras and yields this characterization as a corollary. We give an explicit example of a nuclear operator system that is not completely order isomorphic to a unital C?-algebra. 相似文献
19.
Park Kyueun Kim Youngjin Lee Kyung Jin 《Journal of Radioanalytical and Nuclear Chemistry》2019,319(2):487-531
Journal of Radioanalytical and Nuclear Chemistry - An extensive series of evaluations have been performed as part of an IAEA coordinated research project to study a set of nuclear reactions that... 相似文献
20.
The repassivation kinetics of pure aluminium have been explored in aqueous alkaline solutions as functions of applied anodic
potential and pH by using an abrading electrode technique and a rotating disc electrode. The repassivation rate of the abraded
bare surface of pure aluminium increased with increasing applied anodic potential in aqueous alkaline solutions, while it
decreased with increasing pH. These results revealed that the growth rate of the passivating oxide film is enhanced by an
applied electric field, but it is lowered due to the chemical attack by hydroxyl ions. A potentiostatic anodic current decay
transient obtained from the abraded electrode surface showed a constant repassivation rate in neutral and weakly alkaline
solutions. In contrast, in concentrated alkaline solutions it was observed to consist of three stages: a high repassivation
rate in the initial stage due to a high formation rate of the oxide film on the abraded bare surface; a zero value of the
repassivation rate in the second stage due to the dissolution of the oxide film by the attack of OH−; a high repassivation rate in the third stage due to a lowered dissolution rate of the oxide film. The dissolution rate of
the passivating oxide film was observed to depend on the removal rate of aluminate ions from the oxide/solution interface.
Received: 1 April 1998 / Accepted: 3 July 1998 相似文献