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891.
892.
... Despite the need for physicians to be knowledgeable about and open to advances in genetic technology, little is known about the level of preparedness of primary care physicians to offer new genetic tests. Evidence suggests that several barriers exist to physicians adopting genetic tests. These include lack of knowledge, inability to interpret probabilistic information, low tolerance for uncertainty, negative attitudes about their responsibility for genetic counseling and testing, lack of confidence in their clinical skills, and unfamiliarity with ethical issues raised by testing. This paper will explore some of these barriers in further depth, discuss the ethical impact of physician unpreparedness on both patient care and the diffusion of genetic tests, and describe a study that is currently underway to investigate some of these issues. 相似文献
893.
In this work, we have calculated the optimal surface area per amphiphile molecule using a two-dimensional gas of electric dipoles interacting with hard The optimal surface area can be evaluated according to a formula (in the two-body approximation) or as a root of an equation (in the three-body approximation). If the equation has more than one positive root, which is greater than the hard core area, then a polydisperse dimensional distribution of supramolecular aggregates is possible. 相似文献
894.
In this paper we present a model for the ion exchange effects in protein adsorption. The model is applied to chromatography of lysozyme on strong cation exchanger ‘mono S’. The experimental and general thermodynamic aspects have been discussed in Part 1, the preceding paper. The main modelling assumptions are (i) the charge regulation is confined to the small layer of contact between adsorbed protein and exchanger surface, (ii) the contact layer as a whole is electroneutral and (iii) the number of protein acid/base groups and exchanger surface acid groups which participate in the ion exchange is proportional to the area of the contact layer. The model is fitted to the experimental data by adjustment of only two or three parameters. The experimental co-adsorption numbers are very well reproduced. A few conspicuous features emerge: (i) the number of protein acid/base groups and exchanger surface acid groups in the contact layer varies with the medium conditions, such that the number is higher when the interaction between protein and exchanger surface is stronger. (ii) There is indirect evidence for structural alterations in the upper layers of the exchanger surface: the adsorbed protein is probably partly ‘buried’ in the surface. 相似文献
895.
The induced dipole moment of a purple membrane parallel to the membrane surface was analysed based on the two-dimensional fluctuation theory of counterions. The observed polarizability previously measured by electric dichroism and its dependence on the membrane size were derived from theory for the case where the interaction between counterions was screened. The screening effect of salts on the induced dipole moment was estimated from the theory on diffuse double layers. 相似文献
896.
茎用芥菜的离休培养及植株再生 总被引:1,自引:0,他引:1
植物名称:茎用芥菜(Brassica juncea var.tumida)。材料类别:幼叶、子叶。培养条件:以MS为基本培养基,诱芽培养基为:(1)MS BA 2mg/L(单位下同) NAA 0.2;(2)MS BA2 NAA0.5;(3)M8 BA4 NAA0.1.(4)MSS BA4 NAA 0.2;(5)MS BA4 NAA 1.0。生根培养基为:(6)MS NAA 0;(7)MS NAA 0.1;(8)MS NAA 0.5;(9)MS 相似文献
897.
The development of the leaf-sheath pulvinus of oat (Avena sativa L. cv. Victory) was studied in terms of its competency to respond to gravistimulation. Stages of onset of competency, maximum competency and loss of competency were identified, using the length of the supertending internode as a developmental marker. During the early phases in the onset of competency, the latency period between stimulus and graviresponse decreased and the steady state response rate increased significantly. When fully competent, the latency period remained constant as the plant continued to develop, suggesting that the latency period is relatively insensitive to quantitative changes (e.g., in carbohydrate or nutrient availability) at the cell level within the plant. In contrast, the response rate was found to increase with plant development, indicating that graviresponse rate is more strongly influenced by quantitative cellular changes. The total possible graviresponse of a single oat pulvinus was confirmed to be significantly less than the original presentation angle. This was shown to not result from a loss of competency, since the graviresponse could be reinitiated by increasing the presentation angle. As a result of the low overall graviresponse of individual pulvini, two or more pulvini are required to bring the plant apex to the vertical. This was determined to occur though the sequential, rather than simultaneous, action of successive pulvini, since a given pulvinus lost competency to gravirespond shortly after the next pulvinus became fully competent. 相似文献
898.
齿龈内阿米巴生态的研究 总被引:1,自引:0,他引:1
齿龈内阿米巴是Gros氏从人牙垢中首次发现。后由Von Prowazek(1904)作了描述。许多学者认为它是非病源原虫。国内将其列入“罕见”人体寄生虫。但我们对内蒙古医学院口腔科门诊病人及正常人作阿米巴感染与疾病关系调后证明其在人群中感染普遍并与牙周病有关。为了解其流行与环境关系而对其生态进行研究。 相似文献
899.
霍乱弧菌肠毒素基因在大肠杆菌的表达 总被引:1,自引:0,他引:1
霍乱毒素基因在大肠杆菌获得了表达,在大肠杆菌中产生的毒素,具有霍乱毒素同样的生物活性、抗原性和免疫原性。但它产生的霍乱毒索,90%是保持在胞内的,其毒性可被胰酶激活。 相似文献
900.