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排序方式: 共有211条查询结果,搜索用时 15 毫秒
1.
N. Leclerc A. Michaud K. Sirois J.‐F. Morin M. Leclerc 《Advanced functional materials》2006,16(13):1694-1704
New electroactive and photoactive conjugated copolymers consisting of alternating 2,7‐carbazole and oligothiophene moieties linked by vinylene groups have been developed. Different oligothiophene units have been introduced to study the relationship between the polymer structure and the electronic properties. The resulting copolymers are characterized by UV‐vis spectroscopy, size‐exclusion chromatography, and thermal and electrochemical analyses. Bulk heterojunction photovoltaic cells from different copolymers and a soluble fullerene derivative, [6,6]‐phenyl‐C61 butyric acid methyl ester, have been fabricated, and promising preliminary results are obtained. For instance, non‐optimized devices using poly(N‐(4‐octyloxyphenyl)‐2,7‐carbazolenevinylene‐alt‐3″,4″‐dihexyl‐2,2′;5′,2″;5″,2″′;5″′,2″″‐quinquethiophenevinylene 1″,1″‐dioxide) as an absorbing and hole‐carrier semiconductor exhibit power conversion efficiency up to 0.8 % under air mass (AM) 1.5 illumination. These features make 2,7‐carbazolenevinylene‐based and related polymers attractive candidates for solar‐cell applications. 相似文献
2.
BACKGROUND: To describe abortion utilization in the Canton of Vaud (Switzerland) and to identify desirable changes in the data collection system to improve the epidemiologic monitoring METHODS: Retrospective survey of the 5600 abortion requests to the Canton Health Authority for resident women between 1990 and 1993. RESULTS: Nine women out of 1000 residents requested an abortion, but the abortion rate was higher among women of foreign origin compared to Swiss women (17/1000 vs. 6/1000, p < 0.0001). The proportion of terminated recognized conceptions was 127/1000, and the ratio of IVG to livebirths was 0.18. The abortion rate was lower during adolescence (6/1000) or after 40 years of age (1.8/1000), whereas the proportion of terminated conceptions was highest at these ages (527/1000 and 312/1000). Abortion utilization in Canton of Vaud is among the lowest. CONCLUSIONS: Although these indicators do reflect a satisfactory accessibility and use of family planning services, improvements could be made. A better knowledge of the causes (motives, contraceptive method, reproductive history) and of the consequences of abortion (psycho-social implications, medical complications) would allow to design more focused prevention strategies and to fit health services to current needs. Updating the 1942 Swiss legislation is also desirable. 相似文献
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5.
A Dumonceaux L Michaud M Bonnevalle P Debeugny F Gottrand D Turck 《Canadian Metallurgical Quarterly》1998,5(9):996-999
BACKGROUND: Trichobezoars are composed of hair or fibres. The typical patient presenting with a trichobezoar is an adolescent girl experiencing mental disturbance or retardation. CASE REPORT: Three girls with trichobezoars were seen. Two of them, 4 and 15 years old, had serious digestive antecedents (corrosive oesophagogastritis and oesophageal atresia, respectively) and had undergone previous surgery. The third was a 13-year-old mentally retarded girl. In two cases, an enzymatic dissolution trial was unsuccessful, requiring secondary surgical removal after, in one case, ineffective gastroscopic removal complicated by an oesophageal perforation. The third child had an initial operative removal. DISCUSSION: Serious digestive antecedents may favour bezoars, a diagnosis that must be evoked in such patients presenting with chronic digestive symptoms. Enzymatic dissolution is ineffective for large bezoars, and gastroscopic removal carries some risks such as perforation or intestinal obstruction. Operative removal is usually indicated. Psychiatric follow-up is needed to prevent this complication in children with serious digestive antecedents and to reduce the risk of recurrences. 相似文献
6.
Andreas Mortensen Ph.D. Veronique J. Michaud Ph.D. Merton C. Flemings Sc.D. 《JOM Journal of the Minerals, Metals and Materials Society》1993,45(1):36-43
Pressure infiltration of liquid metal is one of the most important processing routes for the production of aluminum-matrix composites having a self-supporting reinforcement phase. This article briefly examines the physical phenomena governing infiltration processes, to present practical guidelines derived from their analysis for optimization of the process and the materials produced. Engineering aspects that are pertinent to infiltration techniques, including preform preparation, process configurations, flow control, and innovative processes, are summarized. 相似文献
7.
B Le Fourn JY Lebatard-Sartre F Gousset-Lejeune JL Michaud M Pannier 《Canadian Metallurgical Quarterly》1994,39(6):715-724
Thoracic empyema (development of suppuration in the thoracic cavity, usually after pneumonectomy) remains a serious complication which is difficult to treat. Failure of classical procedures (lavage-drainage) in the treatment of certain forms of pleural empyema (post-pulmonary resections), with or without associated fistula, led the authors to use the pedicled omental flaps filling material for the chronic empyema cavity. They report their experience (6 cases over a period of 4 years) and define the indications. Omentoplasty has a real place, next to myoplasty, in the therapeutic arsenal for chronic empyema due to its detersion capacity, particularly useful in a "septic" context and because of its volume which is usually sufficient in retracted cavities. The existence of an associated bronchial fistula, history of radiotherapy, posterolateral thoracostomy (sectioned latissimus dorsi) are additional reasons to prefer omentoplasty over myoplasty. 相似文献
8.
BK Yoder WG Richards C Sommardahl WE Sweeney EJ Michaud JE Wilkinson ED Avner RP Woychik 《Canadian Metallurgical Quarterly》1996,50(4):1240-1248
Autosomal recessive polycystic kidney disease (ARPKD) is characterized by the formation of large collecting tubule and ductular cysts that often result in renal insufficiency within the first decade of life. Understanding the process leading to cyst formation will require the identification and characterization of genes involved in the etiology of this disease. In this regard, we previously described the generation of a mouse model (TgN737Rpw) for ARPKD and the cloning of a candidate gene. Here we show direct involvement of the Tg737 gene in collecting duct cyst formation by expressing the wild-type Tg737 cDNA as a transgene in TgN737Rpw mutants. In contrast to TgN737Rpw mutants, the "rescued" animals survive longer, have normal renal function and normal localization of the EGFr to the basolateral surfaces of collecting duct epithelium. 相似文献
9.
Intelligence has been an object of study for a long time. Different architectures try to capture and reproduce these aspects into artificial systems (or agents), but there is still no agreement on how to integrate them into a general framework. With this objective in mind, we propose an architectural methodology based on the idea of intentional configuration of behaviors. Behavior‐producing modules are used as basic control components that are selected and modified dynamically according to the intentions of the agent. These intentions are influenced by the situation perceived, knowledge about the world, and internal variables that monitor the state of the agent. The architectural methodology preserves the emergence of functionality associated with the behavior‐based paradigm in the more abstract levels involved in configuring the behaviors. Validation of this architecture is done using a simulated world for mobile robots, in which the agent must deal with various goals such as managing its energy and its well‐being, finding targets, and acquiring knowledge about its environment. Fuzzy logic, a topologic map learning algorithm, and activation variables with a propagation mechanism are used to implement the architecture for this agent. 相似文献
10.
Side effects of orally administered bismuthic salts have been known for many years. Many systems are involved, including the digestive and urinary. The authors discuss a recently discovered effect on the central nervous system, termed "bismuth encephalopathy". In the light of the medical literature reviewed, two original aspects are stressed: the clinical symptoms are stereotyped and completely reversible, and the distribution of the disease is almost epidemic, being limited in time and space. The prodromes include confusion, asthenia, slowing of mental functions and disturbance of gait. The clinical picture is dominated by four major symptoms: confusion (again), ataxia, dysarthria and, above all, myoclonic jerks. In conclusion, various pathogenetic hypotheses are considered. The purpose of this study is to enable the general practitioner to detect the development of this condition early in treatment with oral bismuthic salts. Withdrawal of the medication always results in normalization of the patient's condition. 相似文献