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61.
滇牡丹遗传多样性的ISSR分析   总被引:36,自引:0,他引:36  
应用ISSR标记对中国西南地区特有植物滇牡丹(Paeonia delavayi)的遗传多样性进行了研究。从100个引物中筛选出10个用于正式扩增,在取自16个自然居群和1个迁地保护居群的511个个体中,检测到92个多态位点。在居群水平上,多态位点百分率(PPB)为44.61%,Nei′s基因多样性指数(H)和Shannon信息指数(I)分别为0.1657和0.2448。在物种水平上,多态位点百分率(PPB)为79.31%,Nei′s基因多样性指数(H)和Shannon信息指数(I)分别为0.2947和0.4355。居群间的遗传分化系数(GST)达0.4349。结果表明:滇牡丹遗传多样性水平较高,居群间遗传分化较大。结合以前的研究结果,对滇牡丹的现状进行评估的结果显示,滇牡丹并不濒危。  相似文献   
62.
湖丹皮脂溶性化学成分研究   总被引:2,自引:0,他引:2  
利用柱层析方法,从湖丹皮70%乙醇提取物的氯仿萃取部位分离得到5个化合物。运用理化及波谱方法,它们分别鉴定为丹皮酚(1)、3,6-二羟基-4-甲基苯乙酮(2)、去甲基丹皮酚(3)、3,3’-二甲氧基鞣花酸(4)和胡萝卜苷(5)。其中化合物4、5为首次从该种植物中分离得到。HPLC研究表明,湖丹皮中的去甲基丹皮酚含量高于国内其它产地。  相似文献   
63.
Winter pruning is a cultural practice used to modify vegetative growth, which is likely to affect the development of pests. However, it has been poorly defined as a cultural method for diminishing the population levels of the pomegranate aphid Aphis punicae (Hemiptera, Aphididae) in pomegranate orchards. This study aimed to evaluate the impact of winter pruning of pomegranate on A. punicae population and their natural enemies. The results showed that winter pruning significantly decreased the population of A. punicae (p < 0.05) in pomegranate. Also, number of natural enemies decreased in pomegranate trees after winter pruning. This technical practice affects the number of winged and wingless individuals, the mean relative growth rate, the specific age of the population and the infestation rate. Winter pruning for A. punicae control in pomegranate orchards is highly recommended.  相似文献   
64.
Cenk Saracoglu conceptualizes the antipathy towards Kurdish migrants manifesting in certain cities of Turkey since the early 2000s as ‘exclusive recognition’ in his article ‘“Exclusive recognition”: the new dimensions of the question of ethnicity and nationalism in Turkey’ published in Ethnic and Racial Studies 32(4). According to the author, these recent developments represent ‘a historically specific ethnicization process’ and its sources cannot be found directly and only in historical discourses and policy of mainstream Turkish nationalism. In this note, I contradict the author's claims by asserting that the recent manifestations of anti-Kurdish sentiments are an extension of the ongoing policies of Turkish national identity based on Turkish nationalism.  相似文献   
65.
Xenophobia in post-apartheid South Africa has become a major issue. Much of the hostility is directed at Africans from countries north of Southern Africa who are often easily distinguishable due to their physical features, distinctive dress and inability to speak the indigenous languages. This article focuses on immigrants and asylum seekers from two countries, Nigeria and the Democratic Republic of Congo. Both groupings have experienced significant antagonism and prejudice from the local population, more especially from black South Africans. The article describes and analyses the interaction of the two groupings in question with the local populace and authorities. What is argued is that during the apartheid era the restrictions on black immigration meant that the number of black foreigners was limited. Since 1990, however, there has been a substantial increase in illegal and legal migration from Southern African countries and countries further north. This increase, in a context of growing unemployment and crime, limited infrastructural growth and fiscal resources, has intensified xenophobia against foreign Africans. The article is mainly based on in-depth interviews with Nigerian and Congolese informants living in Johannesburg's inner city.  相似文献   
66.
As interest in ethnics and their entrepreneurial activities has grown in recent years, sociologists have come to emphasize the importance of ethnic social structures as the source of actions propelling business growth. In a sign of convergence with the ‘new economic sociology’, recent literature suggests that embeddedness in ethnic networks and communities leads to cooperative, if not conformist, behaviour among ethnic economic actors. This article looks at the ‘other side’ of embeddedness, through a case‐study of African‐American, Caribbean, Korean and white construction contractors in New York City. I argue that, in construction, the embeddedness of economic behaviour in ongoing social relations among a myriad of social actors impedes access to outsiders. Embeddedness contributes to the liabilities of newness that all neophytes encounter, breeding a preference for established players with track records. However, the convergence of economic and ethnic ties has a further baneful effect, since outsiders also fall outside those networks that define the industrial community. While African‐American, Caribbean and Korean outsiders all experience these barriers in similar ways, they differ in the adaptive strategies that they have pursued. African Americans appear to be most disadvantaged, in part because they have been the most exposed to the social closure that results from the mobilization of white ethnics’ social capital. By contrast, Caribbeans and Koreans entered the labour market in societies where racial domination played little or no role in labour market outcomes ‐ a considerable asset since construction skills are transferable from one society to another. The Koreans appear to be the most embedded in ethnic networks, through which they secure jobs and skilled labour, though class factors play a role here as well and even the Koreans must reach out beyond the ethnic community for a clientele. By contrast, ethnic solidarity operates less powerfully among the black contractors, who are tied to a community where intra‐ethnic diversity and internal competition have grown as a result of immigration. In the absence of an ethnic market, black'entrepreneurs turn to the state, whose requirements and dependence on union labour expose black builders to risks from which their Korean counterparts are sheltered.  相似文献   
67.
A process was developed to produce a characteristic milk gel. Raw and market milk samples were freeze-concentrated using bacterial ice nuclei. The concentrates were kept at 5°C and compressed at 300–600 MPa for 5 min. The combination of the freeze concentration and the pressurization gave a milk gel without adding any gelling agents. The addition of sugar at 10% to the concentrated milk improved its gel strength and viscoelasticity. The gel was characterized by a phase transition at about 62–75°C.  相似文献   
68.
To improve the efficacy of the conformationally restricted BACE1 inhibitors, structural modifications were investigated using two strategies: (a) modification of the terminal aromatic ring and (b) insertion of a spacer between the aromatic rings. In the latter approach, another type of inhibitor 17 bearing an ethylene spacer between two aromatic rings was found to exhibit good BACE1 inhibitory activity, while the corresponding conformationally unrestricted compound 25 showed no activity. This result revealed an interesting effect of a conformational restriction with a cyclopropane ring.  相似文献   
69.
The synthesis of racemic tetrahydrocurcumin- (THC-), tetrahydrodemethoxycurcumin- (THDC-) and tetrahydrobisdemethoxycurcumin- (THBDC-) dihydropyrimidinone (DHPM) analogues was achieved by utilizing the multi-component Biginelli reaction in the presence of copper sulphate as a catalyst. The evaluation of acetylcholinesterase inhibitors for Alzheimer’s disease of these compounds showed that they exhibited higher inhibitory activity than their parent analogues. THBDC–DHPM demonstrated the most potent inhibitory activity with an IC50 value of 1.34 ± 0.03 μM which was more active than the approved drug galanthamine (IC50 = 1.45 ± 0.04 μM).  相似文献   
70.
Alzheimer’s disease drug discovery regarding exploration into the molecules and processes has focused on the intrinsic causes of the brain disorder correlated with the accumulation of amyloid-β. An anti-amyloidogenic bis-styrylbenzene derivative, KMS80013, showed excellent oral bioavailability (F = 46.2%), facilitated brain penetration (26%, iv) in mouse and target specific in vivo efficacy in acute AD mouse model attenuating the cognitive deficiency in Y-maze test. Acute toxicity (LD50 >2000 mg/kg) and hERG channel inhibition (14% at 10 μM) results indicated safety of KMS80013.  相似文献   
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