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1.
According to a 1991 study of sexual behavior based on a random sample of heterosexual undergraduates at a Midwestern university, 80% of the males and 73% of the females had experienced vaginal or anal intercourse. The average age at first vaginal intercourse was 17.2 years for both sexes. Seventeen percent of the sexually experienced males and 18% of the sexually experienced females had engaged in heterosexual anal intercourse; among these respondents, the average age at first anal intercourse was 20.3 for males and 19.1 for females. Although less than four years, on average, had elapsed since the respondents had first had vaginal intercourse, males reported an average of 8.0 lifetime vaginal-sex partners and females reported an average of 6.1. Overall, the findings from this random sample of students are similar to those from a 1988 convenience sample of the same college population. 相似文献
2.
Reinisch June M.; Sanders Stephanie A.; Ziemba-Davis Mary 《Canadian Metallurgical Quarterly》1988,43(11):921
To create the behavior-change programs essential for limiting the acquired immune deficiency syndrome (AIDS) epidemic, we must obtain a precise understanding of the sexual behavior, knowledge, and attitudes of our nation's various ethnic, racial, social, age, regional, and sexual orientation groups. Such information is necessary for developing the precisely targeted educational programs that currently are our most effective means of reducing risk behaviors and halting the spread of the disease in the United States. These behavioral data are also crucial to biomedical investigations, making possible the identification of appropriate subjects for programs ranging from the testing of vaccines to the evaluation of the threat to pregnant women and their offspring. In this article, we summarize data on sexual behaviors associated with the transmission of the AIDS virus (i.e., human immunodeficiency virus [HIV]) and discuss selected issues relevant to the conduct of research on human sexuality. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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N Reinisch S Kiechl C Mayr P Schratzberger S Dunzendorfer CM K?hler T Buratti J Willeit CJ Wiedermann 《Canadian Metallurgical Quarterly》1998,28(10):787-792
BACKGROUND: In atherosclerosis, both reductions and elevations in plasma levels of antioxidants have been reported. This study investigated total antioxidant capacity of plasma from subjects with atherosclerotic disease. MATERIALS AND METHODS: The study population consisted of 48 men with or without carotid atherosclerosis. At baseline (1990) carotid arteries were evaluated by duplex sonography and plasma samples were obtained for testing antioxidant capacity by two different test systems. One assay system used neutrophils from healthy volunteers as a source of oxygen free radicals activating the non-fluorescent dichlorofluorescin diacetate in the presence of antioxidant containing plasma from study subjects. In the other test system, total plasma antioxidants were detected colorimetrically by using 2,2'-azino-di-(3-ethylbenzthiazoline sulphonate), metmyoglobin and superoxide in the presence of plasma. Carotid arteries were re-evaluated for the development of new plaques 5 years later (1995). RESULTS: Increased baseline total antioxidant capacity of plasma was significantly associated with the development of new atherosclerotic lesions during a period of 5 years. CONCLUSIONS: Endogenous antioxidant capacity of plasma is increased in patients with active atherosclerotic disease. As scavenging of oxygen free radicals is thought to protect from atherogenesis, elevated antioxidative capacity may represent an adaptive mechanism. 相似文献
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Quantum Chemical MNDO-, AM1-, and PM3-Studies of α-D -Glucose Acetates, -Benzoates and -(Trichloro)Acetates as Models for the Respective Amylose Compounds. Heats of formation have been calculated for α-D-Glucose and also for its mono-, di- and trisubstituted derivatives (acetates, benzoates and (thrichloro)acetates in the positions 2, 3 and 6), applying the semiempirical quantum chemical methods MNDO, AM1 and PM3. When only one hydroxyl is substituted, the thermodynamic probability of generation decreases as 6>3>2 (acetates), 2>6>3 (benzoates) and 6>2>3 ((thrichloro)acetates). Generation of glucose monoacetate increases the reactivity of acetylation for both of the other OH groups. That was not established for benzoates and (trichloro)acetates. For comparison, the heats of formation have been calculated for all unbranched dodecanols and also for their acetates, benzoates and (trichlor)acetates. Enthalpies of reaction were estimated for all considered compounds taking into account the corresponding acid chlorides, one molecule of pyridine and the generation of pyridinium hydrochloride. It was shown that, generally, the reactivity of the dodecanols is higher than that of unsubstituted and substituted glucose. The results are discussed with regard to preparative application. 相似文献
5.
Fluorescence has been suggested as a method with which to detect and identify bacterial spores. To better understand the nature of the fluorescence signal, we observed the intrinsic steady-state fluorescence and phosphorescence spectra of Bacillus globigii (BG) in both dried and aqueous forms. In vitro, dried, and suspension forms of BG were measured at room temperature in 300-600-nm excitation wavelengths. Also, the phosphorescence of dry BG spores was measured at room temperature at 300-600-nm excitation wavelengths. The wet BG spores exhibited a strong maximum in their fluorescence spectrum, with the peak excitation wavelength near 300 nm and emission wavelength near 400 nm. When the BG was dried, this peak shifted to an approximately 450-nm excitation maximum and an 500-nm emission maximum. The difference between the wet and the dry spore fluorescence spectra cannot be explained by the phosphorescence of the dry spores. Other changes must take place when the spores are wet to account for the large changes observed in the spectrum. 相似文献
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A series of eye-tracking and categorization experiments investigated the use of speaking-rate information in the segmentation of Dutch ambiguous-word sequences. Juncture phonemes with ambiguous durations (e.g., [s] in 'eens (s)peer,' “once (s)pear,” [t] in 'nooit (t)rap,' “never staircase/quick”) were perceived as longer and hence more often as word-initial when following a fast than a slow context sentence. Listeners used speaking-rate information as soon as it became available. Rate information from a context proximal to the juncture phoneme and from a more distal context was used during on-line word recognition, as reflected in listeners' eye movements. Stronger effects of distal context, however, were observed in the categorization task, which measures the off-line results of the word-recognition process. In categorization, the amount of rate context had the greatest influence on the use of rate information, but in eye tracking, the rate information's proximal location was the most important. These findings constrain accounts of how speaking rate modulates the interpretation of durational cues during word recognition by suggesting that rate estimates are used to evaluate upcoming phonetic information continuously during prelexical speech processing. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
9.
Summary Poly-p-trimethylsilylphenylmethacrylate(75)-co-glycidylmethacrylate (25) containing aromatic bisazides exhibits uv sensitivity as a negative type photoresist. Sensitometric data have been evaluated. The pressure-dependant reactivity under the conditions of oxygen reactive ion etching was determined. 相似文献
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