全文获取类型
收费全文 | 80篇 |
免费 | 2篇 |
专业分类
化学 | 34篇 |
数学 | 4篇 |
物理学 | 44篇 |
出版年
2021年 | 1篇 |
2017年 | 1篇 |
2016年 | 3篇 |
2014年 | 1篇 |
2013年 | 3篇 |
2012年 | 1篇 |
2011年 | 6篇 |
2010年 | 2篇 |
2009年 | 1篇 |
2008年 | 3篇 |
2007年 | 4篇 |
2006年 | 2篇 |
2005年 | 3篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2002年 | 5篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 7篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有82条查询结果,搜索用时 656 毫秒
31.
32.
S. Heath Wanamaker Kevin J. Schmitt Doug A. Lupher Nathan C. Stockman David S. Brooks Ryan A. Parks Thatcher D. Reist Matthew R. Kyle Pedro L. Muiño 《The Chemical Educator》2000,5(1):14-16
Hydrogen is produced by the reaction between zinc and hydrochloric acid. This reaction is used to illustrate the importance of considering thermodynamics when designing a chemical reactor. The gas released is collected in soap bubbles that rise in the air, indicating that a lighter than air gas has been produced. The bubbles can be lit to add a dramatic effect to the demonstration. The reaction is highly exothermic, raising the temperature of the reaction materials and the reactor. Batch operation of this reactor would require short cooling periods between reactions. Alternatively, a modification of the design is suggested to allow for continuous cooling of the vessel, which would allow semicontinuous operation of the reactor. (Zinc would have to be periodically replenished as it is consumed in the reaction.) The consequences associated with the cooling of the vessel are discussed. 相似文献
33.
34.
35.
36.
37.
Sigmatropic Rearrangement of Vinyl Aziridines: Expedient Synthesis of Cyclic Sulfoximines from Chiral Sulfinimines 下载免费PDF全文
Dr. Toni Moragas Ryan M. Liffey Dr. Dominika Regentová Jon‐Paul S. Ward Justine Dutton Dr. William Lewis Prof. Ian Churcher Dr. Lesley Walton Dr. José A. Souto Prof. Robert A. Stockman 《Angewandte Chemie (International ed. in English)》2016,55(34):10047-10051
A novel rearrangement of 2‐vinyl aziridine 2‐carboxylates to unusual chiral cyclic sulfoximines is described herein. The method allows the synthesis of substituted cyclic sulfoximines in high yields with complete stereocontrol, and tolerates a wide substrate scope. A one‐pot process starting directly from sulfinimines provides access to complex chiral sulfoximines in only two steps from commercially available aldehydes. A mechanistic hypothesis and synthetic application in the formal synthesis of trachelanthamidine, by transformation of a cyclic sulfoximine into a pyrroline, is also disclosed. 相似文献
38.
Stockman BJ 《Journal of the American Chemical Society》2008,130(18):5870-5871
19F NMR-based methods have found utility in activity-based screening assays. However, because enzymes catalyze a diverse set of reactions, a large variety of fluorinated substrates would need to be identified to target each one separately. We have developed a more streamlined approach that is applicable to many enzymes that utilize ATP as a substrate. In this method, a fluorine-containing ATP analogue, 2-fluoro-ATP, is used to monitor the reaction. Applications are described for nicotinamide adenine dinucleotide synthetase and 3-phosphoinositide dependent kinase-1. Fragment screening results for the latter indicate that this technique can identify compounds that inhibit as well as activate reactions. The present results, together with previous biochemical studies from other laboratories, have shown that 2-fluoro-ATP can serve as a substrate for nine enzymes that are representative of three of the six enzyme subclasses, namely the transferases, hydrolases, and ligases. This suggests that 2-fluoro-ATP is suitable as a universal tool for screening ATP-requiring enzymes. Importantly, 2-fluoro-ATP has been determined to be a valid substrate for a variety of kinases, including both small molecule and protein kinases, suggesting that it may be useful for investigating the large number of pharmaceutically relevant kinases. 相似文献
39.
Karatholuvhu MS Sinclair A Newton AF Alcaraz ML Stockman RA Fuchs PL 《Journal of the American Chemical Society》2006,128(39):12656-12657
The synthesis of (+/-)-histrionicotoxin has been achieved in just nine steps using a two-directional synthesis strategy. Key reactions include a two-directional cross-metathesis, a tandem oxime formation/Michael addition/1,4-prototopic shift/[3 + 2]-cycloaddition cascade, a selective Z,Z-bisenyne formation, and a one-pot N-O and bischloroacetylene reduction. 相似文献
40.
L.S. Muratov M.I. Stockman L.N. Pandey T.F. George W.J. Li B.D. McCombe J.P. Kaminski S.J. Allen W.J. Schaff 《Superlattices and Microstructures》1997,21(4):501-508
We report the first far-infrared linear and non-linear (saturation) magneto absorption experiments of coupled subband-Landau level excitations in a series of modulation-doped double-coupled multiple quantum-well (MQW) structures. Non-linear spectroscopy is carried out with a free electron laser. A plot of energy versus magnetic field for 4 laser lines at low intensity and high intensity is compared with linear (Fourier transform) spectroscopy at low and high temperatures. An exact numerical solution of the Schrödinger equation for this coupled system is also obtained and compared with experiments. Results show that the feature observed at high laser intensity and high temperature is due to transitions from the 1st-excited state of the coupled system to the higher excited states. Based on this, a simple 2-level model is developed, and with a layer-by-layer analysis for MQW systems, the electron lifetime of the first-excited state is obtained. 相似文献