全文获取类型
收费全文 | 124篇 |
免费 | 0篇 |
专业分类
系统科学 | 3篇 |
教育与普及 | 5篇 |
现状及发展 | 11篇 |
研究方法 | 6篇 |
综合类 | 98篇 |
自然研究 | 1篇 |
出版年
2012年 | 3篇 |
2011年 | 6篇 |
2010年 | 1篇 |
2009年 | 2篇 |
2008年 | 14篇 |
2007年 | 10篇 |
2006年 | 6篇 |
2005年 | 11篇 |
2004年 | 11篇 |
2003年 | 7篇 |
2002年 | 7篇 |
2001年 | 9篇 |
2000年 | 10篇 |
1999年 | 2篇 |
1994年 | 2篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1986年 | 5篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1966年 | 3篇 |
1965年 | 1篇 |
排序方式: 共有124条查询结果,搜索用时 0 毫秒
81.
82.
83.
Patterns of mineral nutrient uptake and distribution within the roots, stems, and leaves of Artemisia pygmaea and in the vascular parasite Orobanche fasciculata were investigated. All nutrients studied were magnified over concentrations found in the soil into the host and parasite. Nitrogen, phosphorus, potassium, and zinc were magnified along the flow gradient of soil-roots-stems-leaves of the host. All others increased in the roots and then decreased in the stems and leaves. Orobanche fasciculata concentrated phosphorus, potassium, and sodium over soil and root concentrations while excluding to some degree all others. 相似文献
84.
S. J. Ball Christine E. Heading B. Tranter 《Cellular and molecular life sciences : CMLS》1980,36(7):839-840
Summary The absorption of glycine and proline through the jejunum and ileum of rats with anEimeria nieschulzi infection was impaired when the amino acids were presented to the mucosal surface as either a mixture or the dipeptide, glycyl-proline. 相似文献
85.
86.
87.
88.
89.
90.
The ability to cool and slow atoms with light for subsequent trapping allows investigations of the properties and interactions of the trapped atoms in unprecedented detail. By contrast, the complex structure of molecules prohibits this type of manipulation, but magnetic trapping of calcium hydride molecules thermalized in ultra-cold buffer gas and optical trapping of caesium dimers generated from ultra-cold caesium atoms have been reported. However, these methods depend on the target molecules being paramagnetic or able to form through the association of atoms amenable to laser cooling, respectively, thus restricting the range of species that can be studied. Here we describe the slowing of an adiabatically cooled beam of deuterated ammonia molecules by time-varying inhomogeneous electric fields and subsequent loading into an electrostatic trap. We are able to trap state-selected ammonia molecules with a density of 10(6) cm(-3) in a volume of 0.25 cm3 at temperatures below 0.35 K. We observe pronounced density oscillations caused by the rapid switching of the electric fields during loading of the trap. Our findings illustrate that polar molecules can be efficiently cooled and trapped, thus providing an opportunity to study collisions and collective quantum effects in a wide range of ultra-cold molecular systems. 相似文献