全文获取类型
收费全文 | 252篇 |
免费 | 0篇 |
专业分类
化学 | 214篇 |
数学 | 1篇 |
物理学 | 37篇 |
出版年
2021年 | 2篇 |
2020年 | 3篇 |
2016年 | 3篇 |
2014年 | 2篇 |
2013年 | 3篇 |
2012年 | 2篇 |
2010年 | 2篇 |
2009年 | 4篇 |
2008年 | 2篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2005年 | 1篇 |
2004年 | 5篇 |
2002年 | 1篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1996年 | 11篇 |
1995年 | 10篇 |
1994年 | 3篇 |
1993年 | 7篇 |
1992年 | 10篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 9篇 |
1988年 | 9篇 |
1987年 | 9篇 |
1986年 | 6篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1977年 | 12篇 |
1976年 | 12篇 |
1975年 | 5篇 |
1974年 | 11篇 |
1973年 | 4篇 |
1972年 | 7篇 |
1971年 | 7篇 |
1970年 | 5篇 |
1969年 | 4篇 |
1968年 | 5篇 |
1967年 | 2篇 |
1966年 | 1篇 |
1917年 | 1篇 |
排序方式: 共有252条查询结果,搜索用时 15 毫秒
41.
Skimmianine, folimine, benzamide, and new alkaloid haplotusine (mp 118–119°C, C11H11NO3, M+ 205) have been isolated from the epigeal part ofHaplophyllum obtusifolium Ledeb. growing in the environs of Kora-Koly, Turkmen SSR. By the analysis of spectral characteristics it has been established that haplotusine has the structure of 1,4-dimethoxy-2-quinolone.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 635–636, September–October, 1984. 相似文献
42.
43.
F. N. Dzhakhangirov B. T. Salimov I. A. Bessonova M. N. Sultankhodzhaev 《Chemistry of Natural Compounds》1995,31(6):708-713
A number of diterpene alkaloids (DAs) and their derivatives have been investigated for curaremimetic activity. Their structure-activity relationships and the mechanisms of their action have been studied. Structural fragments of the DAs that are responsible for curaremimetic properties have been revealed. Among the compounds studied, nudicauline and lycaconitine are superior to the curaremimetic drugs melliktin and condelphine.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 841–848, November-December, 1995. Original article submitted April 10, 1995. 相似文献
44.
45.
46.
From the roots of Aconitum septentrionale Koelle we have isolated the new nor- and bisnorditerpenoid alkaloids septerine (1) and septefine (2), each containing a N-methylanthraniloyl fragment. Their structures have been established from IR-, mass-, and PMR-spectral results. Structure (1) for septerine has been confirmed by the formation of lycoctonine on its hydrolysis.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 225–228, March–April, 1996. Original article submitted December 25, 1995. 相似文献
47.
48.
49.
50.
Various diphenylmethane diisocyanate-containing polyurethanes whose soft blocks differ in polarity and crystallizability have been investigated using deformation and scanning calorimetry to ascertain the contribution of different types of intermolecular interaction to elasticity of polyurethane elastomers. The phase composition of polyurethanes being investigated and its dependence on mechanical action have been analyzed on the basis of scanning calorimetry data. By measuring the mechanical work and thermal effect during extension (λ=1–3.5) deformation dependences of internal energy changes and the ratio of energy and entropy changes have been determined as well as energy contributions have been calculated. The data obtained for different temperatures demonstrate that a decrease in the fraction of energy changes is largely due to hard block structurization in the course of re-building the network of hydrogen bonds during deformation. 相似文献