首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   32篇
  免费   0篇
理论与方法论   2篇
现状及发展   13篇
研究方法   3篇
综合类   12篇
自然研究   2篇
  2019年   1篇
  2014年   3篇
  2013年   4篇
  2011年   4篇
  2007年   1篇
  2006年   1篇
  2004年   1篇
  2002年   4篇
  2000年   2篇
  1999年   1篇
  1998年   1篇
  1986年   1篇
  1981年   3篇
  1978年   2篇
  1975年   1篇
  1973年   1篇
  1971年   1篇
排序方式: 共有32条查询结果,搜索用时 316 毫秒
21.
重载流无铠装多芯电缆周围磁场的特性可以用载流平行螺旋线理论模型来解释,而据此推导的简化计算公式可方便地估算电缆周围的磁场,为验证该理论模型的有效性和间化公式的准确度,对电缆周围的极低频磁场进行了基于毕奥-沙伐定律的数值计算和实测,通过数值计算结果和实测值与简化公式估算结果之间的比较,证明了该理论模型的有效性,发现简化计算公式对距电缆轴线0.2m以外的磁场有很高的估算精度,另外,还讨论了电缆所载电流的特性对周围磁场的影响,并提出一些降低多芯电缆系统周围磁场的方法。  相似文献   
22.
23.
24.
In young chickens, the whole oil of nutmeg (200 mg/kg) increased the duration of sleep induced by ethanol (1--4 g/kg), particularly deep sleep. Iproniazid (50-400 mg/kg), a monoamine oxidase inhibitor, did not mimic this effect.  相似文献   
25.
Given two dendrograms (rooted tree diagrams) which have some but not all of their base points in common, a supertree is a dendrogram from which each of the original trees can be regarded as samples The distinction is made between inconsistent and consistent sample trees, defined by whether or not the samples provide contradictory information about the supertree An algorithm for obtaining the strict consensus supertree of two consistent sample trees is presented, as are procedures for merging two inconsistent sample trees Some suggestions for future work are made  相似文献   
26.
5S及16S rDNA序列PCR扩增用于环境军团菌检测   总被引:3,自引:0,他引:3  
军团菌病(Legionnaires’disease)是一种严重的空气传播疾病,在世界各地都常有报道,是由军团菌(Legionela)引起,该菌迄今已鉴定出了44个种,其中18种具致病性,最常见的导致严重病症的种有嗜肺军团菌(L.pneumophila...  相似文献   
27.
28.
29.
We performed a meta-analysis of 14 genome-wide association studies of coronary artery disease (CAD) comprising 22,233 individuals with CAD (cases) and 64,762 controls of European descent followed by genotyping of top association signals in 56,682 additional individuals. This analysis identified 13 loci newly associated with CAD at P < 5 × 10?? and confirmed the association of 10 of 12 previously reported CAD loci. The 13 new loci showed risk allele frequencies ranging from 0.13 to 0.91 and were associated with a 6% to 17% increase in the risk of CAD per allele. Notably, only three of the new loci showed significant association with traditional CAD risk factors and the majority lie in gene regions not previously implicated in the pathogenesis of CAD. Finally, five of the new CAD risk loci appear to have pleiotropic effects, showing strong association with various other human diseases or traits.  相似文献   
30.
Quantum encounters of the cold kind   总被引:2,自引:0,他引:2  
Burnett K  Julienne PS  Lett PD  Tiesinga E  Williams CJ 《Nature》2002,416(6877):225-232
Since the introduction of laser-cooling techniques for neutral atoms in the early 1980s, the study of collisional interactions between atoms and molecules has been extended to the regime of ultracold temperatures. With nanokelvin temperatures now attainable, our ability to probe the interactions, both experimentally and theoretically, has also progressed. Understanding of the subtle and often highly quantum-mechanical effects that are manifest at such low energies has advanced to the point where new precision measurements are matched by highly accurate theoretical calculations. Low-energy phenomena such as Bose-Einstein condensation and the photoassociation of atoms into bound molecules are now accurately described with no free parameters.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号