全文获取类型
收费全文 | 663篇 |
免费 | 48篇 |
专业分类
化学 | 457篇 |
晶体学 | 18篇 |
力学 | 3篇 |
数学 | 88篇 |
物理学 | 145篇 |
出版年
2022年 | 6篇 |
2021年 | 12篇 |
2020年 | 11篇 |
2019年 | 12篇 |
2018年 | 13篇 |
2016年 | 21篇 |
2015年 | 24篇 |
2014年 | 28篇 |
2013年 | 35篇 |
2012年 | 31篇 |
2011年 | 36篇 |
2010年 | 13篇 |
2009年 | 16篇 |
2008年 | 22篇 |
2007年 | 17篇 |
2006年 | 13篇 |
2005年 | 17篇 |
2004年 | 11篇 |
2003年 | 19篇 |
2002年 | 13篇 |
2001年 | 8篇 |
2000年 | 5篇 |
1999年 | 7篇 |
1998年 | 16篇 |
1997年 | 8篇 |
1996年 | 13篇 |
1995年 | 10篇 |
1994年 | 10篇 |
1992年 | 13篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1986年 | 9篇 |
1985年 | 9篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 12篇 |
1981年 | 13篇 |
1980年 | 12篇 |
1979年 | 6篇 |
1978年 | 11篇 |
1977年 | 12篇 |
1975年 | 8篇 |
1973年 | 8篇 |
1969年 | 7篇 |
1965年 | 4篇 |
1934年 | 4篇 |
1912年 | 4篇 |
排序方式: 共有711条查询结果,搜索用时 15 毫秒
81.
82.
83.
U. Starke J. Schardt M. Franke 《Applied Physics A: Materials Science & Processing》1997,65(6):587-596
Received: 21 March 1997 相似文献
84.
Attenuated total reflection leaky-mode spectroscopy is used for a thermo-optical investigation of a clamped film of the ferroelectric vinylidene fluoridetrifluoroethylene copolymer. A hysteresis loop for the optical parameters refractive index and film thickness is found for a full temperature cycle between 25° C and 60° C. In the vicinity of the ferroelectric/paraelectric phase transition increased optical losses are found. 相似文献
85.
86.
87.
The Unexpected Influence of Precursor Conversion Rate in the Synthesis of III–V Quantum Dots 下载免费PDF全文
Daniel Franke Dr. Daniel K. Harris Lisi Xie Prof. Klavs F. Jensen Prof. Moungi G. Bawendi 《Angewandte Chemie (International ed. in English)》2015,54(48):14299-14303
Control of quantum dot (QD) precursor chemistry has been expected to help improve the size control and uniformity of III–V QDs such as indium phosphide and indium arsenide. Indeed, experimental results for other QD systems are consistent with the theoretical prediction that the rate of precursor conversion is an important factor controlling QD size and size distribution. We synthesized and characterized the reactivity of a variety of group‐V precursors in order to determine if precursor chemistry could be used to improve the quality of III–V QDs. Despite slowing down precursor conversion rate by multiple orders of magnitude, the less reactive precursors do not yield the expected increase in size and improvement in size distribution. This result disproves the widely accepted explanation for the shortcoming of current III–V QD syntheses and points to the need for a new generalizable theoretical picture for the mechanism of QD formation and growth. 相似文献
88.
Aurora Molinari Alfonso Oliva Marlene Arismendi Elizabeth Imbarack Cristian Glvez Javier Maldonado Arturo San Feliciano 《Journal of heterocyclic chemistry》2015,52(2):620-622
New fused pyrazolo‐1,4‐naphthoquinones were prepared from the reaction of hydrazines with 6‐(4‐methyl‐3‐pentenyl)‐1,4‐naphthoquinone. The reaction was extended to hydroxylamine to afford the corresponding isoxazolo‐1,4‐napthoquinone compound. 相似文献
89.
90.
Spectroscopic and Kinetic Evidence for the Crucial Role of Compound 0 in the P450cam‐Catalyzed Hydroxylation of Camphor by Hydrogen Peroxide 下载免费PDF全文
Dr. Alicja Franke Prof. Dr. Rudi van Eldik 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(43):15201-15210
The hydroperoxo iron(III) intermediate P450camFeIII–OOH, being the true Compound 0 (Cpd 0) involved in the natural catalytic cycle of P450cam, could be transiently observed in the peroxo‐shunt oxidation of the substrate‐free enzyme by hydrogen peroxide under mild basic conditions and low temperature. The prolonged lifetime of Cpd 0 enabled us to kinetically examine the formation and reactivity of P450camFeIII–OOH species as a function of varying reaction conditions, such as pH, and concentration of H2O2, camphor, and potassium ions. The mechanism of hydrogen peroxide binding to the substrate‐free form of P450cam differs completely from that observed for other heme proteins possessing the distal histidine as a general acid–base catalyst and is mainly governed by the ability of H2O2 to undergo deprotonation at the hydroxo ligand coordinated to the iron(III) center under conditions of pH≥p${K{{{\rm P450}\hfill \atop {\rm a}\hfill}}}$ . Notably, no spectroscopic evidence for the formation of either Cpd I or Cpd II as products of heterolytic or homolytic O?O bond cleavage, respectively, in Cpd 0 could be observed under the selected reaction conditions. The kinetic data obtained from the reactivity studies involving (1R)‐camphor, provide, for the first time, experimental evidence for the catalytic activity of the P450FeIII–OOH intermediate in the oxidation of the natural substrate of P450cam. 相似文献