全文获取类型
收费全文 | 46篇 |
免费 | 1篇 |
专业分类
化学 | 25篇 |
力学 | 3篇 |
数学 | 2篇 |
物理学 | 17篇 |
出版年
2024年 | 1篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2013年 | 5篇 |
2011年 | 2篇 |
2010年 | 1篇 |
2009年 | 1篇 |
2007年 | 1篇 |
2006年 | 2篇 |
2003年 | 1篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1996年 | 1篇 |
1984年 | 1篇 |
1982年 | 5篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1943年 | 1篇 |
排序方式: 共有47条查询结果,搜索用时 46 毫秒
21.
It is reported in the literature that alkylation of simple (unsubstituted) phosphorane with alkyl halide in ethyl acetate leads to equimolar mixture of alkylated phosphorane and salt of the unsubstituted phosphorane. Here we report exclusive formation of alkylated phosphorane from its salt from benzyl bromide in chloroform. This alkylated phosphorane (2) on reaction with 2-hydroxy carbony1 compounds (1a-1) provide E-ethyl Oc-benzyl cinnamates in high yields which on thermal cyclisation gave 3-benzylf 3-benzyl-4-substituted and benzocoumarins. Thus this method can be used conveniently to synthesise above compounds in good yields. 相似文献
22.
23.
24.
Silk fibroin (SF) is an interesting biomaterials with intriguing mechanical, optical, piezoelectric, and biocompatible properties. The present study reports the first magnetic experiments to show that organic radicals in the building blocks of SF induce permanent magnetization in these materials. A saturation magnetization of 2.8 × 10−3 emu g−1 and non-zero remnant magnetization of 2.2 × 10−4 emu g−1 with a coercive field of 65 Oe is observed in multiple SFs. Tightly bound β-sheets of polyglycine-alanine motifs provides sufficient steric hinderance to organic radicals and protects them from attack of reactive species. Moreover, it also shows that silk's ferromagnetic character can be enhanced by simple mechanical stretching and heating. This work demonstrates a new paradigm of magnetic proteins and opens a route toward the biomimetic discovery of iron-free magnetic proteins. 相似文献
25.
KB McTiernan SC Jarvis D Allen R Bol D Scholefield 《Rapid communications in mass spectrometry : RCM》1999,13(18):1803-1807
The composition of dissolved organic matter (DOM) in a soil is the product of a variety of soil processes. Changes in the composition of DOM in water discharged from soil should, therefore, give an important insight into modifications in these soil processes. We hypothesise that these processes in soils, under different grassland management regimes, would be affected to different extents by the short-term disturbance of a storm event and that evidence of this could be detected in delta(13)C and delta(15)N signatures in drainage and surface runoff waters. During a storm event we collected discharge waters from 1 ha grassland lysimeters, with or without artificial drainage, which received contrasting fertiliser inputs, and delta(13)C and delta(15)N signatures were determined. Changes in (13)C enrichment during the storm event were clearly identifiable, as were differences between plots for (13)C and (15)N, illustrating that this technique has potential to be a useful tool for identifying and investigating short- and long-term changes in soil organic matter dynamics. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
26.
Sneha C. Ranade Scott J. Hasty Alexei V. Demchenko 《Journal of carbohydrate chemistry》2013,32(5-6):360-379
Our results indicate that the reactivity and the activation profile of thioimidate glycosyl donors vary significantly depending on the endocyclic heteroatom (N,O,S). Reactivity diminishes in accordance with the following sequence: O > S > N; and this trend stands for a majority of promoters tested. Acyclic glycosyl thioimidates were found to be generally less reactive than the respective cyclic counterparts. The difference in the reactivity was confirmed in direct competition experiments. These findings made possible a two-step one-pot selective activation using thioimidates as the anomeric leaving group of the glycosyl donor and temporary masking group of the glycosyl acceptor. Supplemental materials are available for this article. Go to the publisher's online edition of Journal of Carbohydrate Chemistry to view the supplemental file. 相似文献
27.
In lithiation of acetophenone ketal by butyllithium in diethyl ether, both aromatic lithiation and ketal ring cleavage are observed. 相似文献
28.
Synthesis of isodamascone and its analogs, the commercially important aroma compounds, have been accomplished from the readily available 1,5,5‐trimethyl‐2‐cyclohexen‐1‐ol via a short, facile, and simple sequence of reactions in excellent yield. 相似文献
29.
Aslam C. Shaikh Dnyanesh S. Ranade Dr. Pattuparambil R. Rajamohanan Dr. Prasad P. Kulkarni Dr. Nitin T. Patil 《Angewandte Chemie (International ed. in English)》2017,56(3):757-761
Oxidative intramolecular 1,2-amino-oxygenation reactions, combining gold(I)/gold(III) catalysis, is reported. The reaction provides efficient access to a structurally unique ionic pyridinium-oxazole dyad with tunable emission wavelengths. The application of these fluorophores as potential biomarkers has been investigated. 相似文献
30.
The hydromagnetic stability of an incompressible, inviscid, and two-dimensional jet in the presence of a discontinuity in density and conductivity across the jet surfaces is studied against small and large wavelength disturbances. In the equilibrium state the magnetic field is uniform and aligned with the direction of jet velocity. Study of several different cases shows that discontinuity in density or conductivity or in the product of density and conductivity across the jet surfaces has a stabilizing effect on the jet. 相似文献