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   9篇
  免费   0篇
  2020年   1篇
  2013年   3篇
  2010年   1篇
  2008年   1篇
  2001年   1篇
  1994年   1篇
  1986年   1篇
排序方式: 共有9条查询结果,搜索用时 30 毫秒
1
1.
Of all the former Soviet republics, Kazakhstan has what may well be the most untenable interethnic predicament ‐ an ethnic Russian population that is nearly as large as the ethnic Kazakh population. The Russians, moreover, constitute a majority of the population in the northern part of the country, which borders the Russian republic. Having the unenviable task of nation‐building in an increasingly fragmented multi‐ethnic environment, Nazarbaev has made his strategy clear: build a strong unitary Kazakh state by steadily increasing control over the Russian‐dominated provinces of the north. Kazakh action in the north, and Russian response, will determine whether there is a future for a multinational Kazakhstan.  相似文献   
2.
Standard Eucheuma denticulatum ι-carrageenan was degraded with the Alteromonas fortis ι-carrageenase. The most abundant products, the neo-ι-carratetraose and neo-ι-carrahexaose were purified by permeation gel chromatography, and their corresponding 1H and 13C NMR spectra were fully assigned.  相似文献   
3.
The gene pool of Brassica oleracea was enriched via intergeneric somatic hybridization between B. oleracea (2n = 18) and Matthiola incana (2n = 14). One hundred and eighteen plants were obtained from 96 calli. Only four plants (H1, H2, H3 and H4) showed an intermediate phenotype from the parents; among these, H1 and H3 arose from the same callus. Random amplified polymorphic DNA (RAPD), sequence-related amplified polymorphism (SRAP), and cytological analyses confirmed that H1 and H3 were hybrids. The nuclear DNA content of the regenerated plants was determined by flow cytometry. More than half of the plants contained a nuclear DNA content of 1.3 to 3.9 pg/cell, which was higher than the content of B. oleracea but lower than that of M. incana. H1 contained 4.89 ± 0.02 pg of DNA per cell, while H3 nuclear DNA content was estimated at 4.87 ± 0.06 pg/cell. Cytological study of the root-tip cells revealed that the majority of the H1 and H3 hybrid cells contained 28 chromosomes.  相似文献   
4.
Using the 1980 US Population Census data, this article documents the diverse strategies of economic adaptation adopted by a group of working‐age immigrant women: Japanese, Chinese, Filipino, Korean, Indian and Vietnamese. A comparable sample of non‐Hispanic white women serves as the reference group. Striking heterogeneity in the individual and collective resources of these groups, together with differences in labour market opportunities and historical context of immigration, have led to a variety of patterns of labour force participation and methods of income attainment. In order to move beyond the oversimplified image of Asian‐Americans as a model minority in their economic success, the article applies four different theories to the census data ‐ assimilation, dual economy, ethnic‐enclave economy and middleman minority. The article closes with a discussion of theoretical implications and methodological suggestions for future studies concerning labour force position and economic adaptation of minority and immigrant women.  相似文献   
5.
The construction of a swimming pool for the European personnel of one of the fifty or so colonial sugar factories still operating in Java in the mid-1930s was a symptom of the growing 'enclavement' of the Dutch colonial communities on the island during the final decades of the Netherlands India. An earlier phase of Dutch colonialism in the Indies had been characterized by hybrid, inclusivist social practices and cultural assumptions generally labelled indisch or Indo-European. By the inter-war decades of the twentieth century, totok – meaning expatriate – norms and values began to assert their hegemony at virtually all levels of colonial society. Yet ambiguity continues to surround this progress from incorporation to differentiation, as instanced by the inter-war history of the Europeans who lived in the residential compound which the pool was designed to service.  相似文献   
6.
Crossing blocks of Mentha arvensis cv Kalka (menthol mint without carvone) and Mentha spicata cv Neera (carvone mint without menthol) in alternate rows (2:1::Kalka:Neera), and pollination of florets of Kalka with that from Neera, yielded a carvone-rich variant among the open-pollinated seedlings. The variant possesses the hybrid phenotype, including the vigorous M. arvensis growth habit and the synthesis of rich oil aroma supplemented with a menthol tinge (carvone 64%–76% against 58% for the normal carvone mint cv Neera), and thus a novel combination of the essential oil. Chromosome counts and random amplified polymorphic DNA analysis confirmed that this spearmint variant, designated as the variety Neerkalka, is a unique interspecific hybrid (2n=5x=60) of M. arvensis cv Kalka (2n=8x=96) and M. spicata cv Neera (2n=2x=24). Vegetative multiplication of the hybrid was facilitated by its underground sucker-reproducing ability which is otherwise absent in spearmints. The per cent improvement in the variant ranged from 31–97 for herbage yield and 95–317 for oil yield over the standard spearmint varieties (MSS-5, Arka and Neera), with per hectare oil yields of 125.0 kg, 139.0 kg and 65.0 kg, respectively. Received: 25 March 2000 / Accepted: 3 July 2000  相似文献   
7.
Summary The applicability and reliability of RAPD markers were evaluated for an examination of the possible use of RAPD markers to confirm hybridity of somatic hybrids between dihaploids of potato (Solanum tuberosum L.). Most of the primers examined detected polymorphism among either tetraploids or dihaploids, and polymorphism was easily detected even among closely related clones. Most of the examples of polymorphism were confirmed as being the result of amplification from the nuclear genome by a comparison of patterns generated by PCR of clones that carried the same cytoplasm. All the bands of dihaploids were transmitted stably to the respective hybrids. In the absence of primers that generated complementary polymorphic bands for both parents, a mixture of two appropriate primers, each of which generated a band specific to one parent, permitted the simple confirmation of hybridity. Hybridity of all the fusion-derived regenerants of 32 fusion combinations was unequivocally confirmed, a result that suggests that RAPD analysis could be universally applicable to the confirmation of hybridity in the dihaploid breeding of potato.  相似文献   
8.
宽边黄粉蝶(Eurema hecabe)是重要的传粉昆虫,广布于非洲热带区、东洋区、澳洲区及古北区东部,具有较高的学术价值和经济意义。为了深入研究其广泛适应性,确定适合该蝴蝶的全基因组的测序研究策略,我们首先做低覆盖度的基因组Survey测序,然后做大规模的全基因组深度测序。采用第二代高通量的测序技术作为该研究的研究方法,测定了宽边黄粉蝶基因组大小,并利用生物信息学方法估计该种的杂合率、重复序列和GC含量等基因组信息。结果表明:(1)宽边黄粉蝶的基因组大小估计为285.34 Mb,测序深度51×;(2)从K-mer分布曲线发现黄粉蝶基因组有明显的杂合峰,杂合率达1.97%,重复序列比例为35.37%。该研究结果对于揭示宽边黄粉蝶物种的起源和进化及适应性具有重要意义,为宽边黄粉蝶选择全基因组测序策略提供依据。  相似文献   
9.
The effects of race and interracial crossing were examined on six cephalometric measurements among 9,912 schoolchildren in Hawaii. The measurements studied were face height, bizygomatic diameter, bigonial diameter, head breadth, head length, and cephalic index. Racial effects were studied in terms of general racial effect, maternal effect, and hybridity and recombination effects based on a model of diallel cross. Generally, Chinese, Japanese, Koreans, and Filipinos were characterized by longer lateral and smaller anterior-posterior dimensions relative to Caucasians. Maternal effects appeared to be present in the measures of lateral dimension. No clear effects of hybridity and recombination were seen except for bizygomatic diameter, which appears to behave as a partial dominant trait. The racial mean of bizygomatic diameter, or the ratio of this measure to head length, were found to have a relationship with the racial incidences of cleft lip with or without cleft palate.  相似文献   
1
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