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In the nineteen-thirties and -forties, genes were universally believed to be made of protein. Biochemists met Avery, MacLeod and McCarty's discovery, that the transforming factor of pneumococci consists of DNA, with disbelief, and the notion that this was true of genes took a long time to be generally accepted even after Watson and Crick's discovery of its double helical structure. Until Watson's arrival, Kendrew, Crick and I were interested mainly in solving the structure of proteins, but Watson made us think about the structure of genes which determine protein structure.  相似文献   
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OBJECTIVE: To determine whether three-dimensional ultrasonography can increase the ability to evaluate the ovary and follicles, especially in women with polycystic ovary disease (PCOD). DESIGN: Prospective clinical study. SETTING: University hospital endocrine and infertility center. PATIENT(S): Sixty-six patients undergoing routine gynecologic evaluation were divided into two groups: the normal control group consisted of 22 patients, and there were 44 patients with PCOD. INTERVENTION(S): Three-dimensional ultrasonography was performed to store and document whole volumes of the ovaries for evaluation. MAIN OUTCOME MEASURE(S): Three perpendicular planes of bilateral ovaries are rotatable to obtain the largest dimensions. The three-dimensional volume was measured using the trapezoid formula. RESULT(S): The ovaries of the patients with PCOD were larger in size, area, and volume than those of normal controls. CONCLUSION(S): Stroma and volume determinations can be obtained more accurately by three-dimensional images than by traditional ultrasonography. Three-dimensional ultrasonography not only facilitates noninvasive evaluation and volume calculation but also completes the examination in a short time without increasing patient discomfort.  相似文献   
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Metallothionein, a two-domain protein, naturally binds seven gram atoms of divalent ions such as Zn and Cd. Four of the metals (M1, M5, M6 and M7) are found in the alpha-domain and three (M2, M3 and M4) in the beta-domain. Previous studies have shown that metals in the beta-domain are more readily exchangeable, and the level of avidity is site specific. By semi-empirical MNDO modified neglect of diatomic overlap calculations, we found the tendency of binding energy for Cd to be M4 > M2 > M3 [corrected] in the beta-cluster and M5 > M7 > M1, M6 in the alpha-cluster. Thus, the replacement of Zn by Cd can be expected to follow the order M4-->M2-->M3 in the beta-domain and M5-->M7-->M1 or M6 in the alpha-domain. This is reflected by energy differences computed with a series of simulated structures derived from either X-ray crystallography or NMR coordinates.  相似文献   
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