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101.
Blinking     
CLARK RE  LAWSON RW 《Nature》1948,162(4129):970
  相似文献   
102.
无机化学是化学及相关专业的一门重要基础课。在通才教育背景下,如何深化无机化学教学改革?本文在教学理念、教学内容、教学方法和评价体系等四个方面进行了初步的探讨。  相似文献   
103.
文章指出要想在散打运动中取得成绩,必须在观察与分析对手战术及技术的基础上,制定适合于自己机动灵活的战术训练原则以及科学系统的战术训练方法,并在实战中合理地加以运用,从而取得必胜的把握。  相似文献   
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0 IntroductionDue to the success of Internet technology and the emer-gence of wide band network,downloading encoded dig-ital audiovisual content files via HTTP,FTP,etc ,had gainedfavor amongInternet users because of thei mmediate access todesired content . Digital Right Management (DRM) system,can satisfy the content provider by encrypting digital audiovi-sual content andli miting access to onlythose people who haveacquired a proper license to play backthe content[1].DRMas defined bythe …  相似文献   
106.
This paper introduces the conception of open complex giant system and the methodology for dealing with the system, with stress on its profound significance in development of science and technology. The authors conclude that the reductionism underlying the exact science is not suitable to open complex giant system, and the only feasible alternative is the meta-synthetic engineering from the qualitative to the quantitative.  相似文献   
107.
Transgenesis in fish   总被引:1,自引:0,他引:1  
Gene transfer into fish embryo is being performed in several species (trout, salmon, carps, tilapia, medaka, goldfish, zebrafish, loach, catfish, etc.). In most cases, pronuclei are not visible and microinjection must be done into the cytoplasm of early embryos. Several million copies of the gene are generally injected. In medaka, transgenesis was attempted by injection of the foreign gene into the nucleus of oocyte. Several reports indicate that the injected DNA was rapidly replicated in the early phase of embryo development, regardless of the origin and the sequence of the foreign DNA. The survival of the injected embryos was reasonably good and a large number reached maturity. The proportion of transgenic animals ranged from 1 to 50% or more, according to species and to experimentators. The reasons for this discrepancy have not been elucidated. In all species, the transgenic animals were mosaic. The copy number of the foreign DNA was different in the various tissues of an animal and a proportion lower than 50% of F1 offsprings received the gene from their parents. This suggests that the foreign DNA was integrated into the fish genome at the two cells stage or later. An examination of the integrated DNA in different cell types of an animal revealed that integration occurred mainly during early development. The transgene was found essentially unrearranged in the fish genome of the founders and offsprings. The transgenes were therefore stably transmitted to progeny in a Mendelian fashion. Southern blot analysis revealed the presence of possible junction fragments and also of minor bands which may result from a rearrangement of the injected DNA. In all species, the integrated DNA appeared mainly as random end-to-end concatemers. In adult trout blood cells, a small proportion of the foreign DNA was maintained in the form of non-integrated concatemers, as judged by the existence of end fragments. The transgenes were generally only poorly expressed. The majority of the injected gene constructs contained essentially mammalian or higher vertebrates sequences. The comparison of the expression efficiency of these constructs in transfected fish and mammalian cells indicates that some of the mammalian DNA sequences are most efficiently understood by the fish cell machinery. Chloramphenicol acetyl transferase gene under the control of promoters from Rous sarcoma virus, and human cytomegalovirus, was expressed in several tissues of transgenic fish. Chicken delta-crystallin gene was expressed in several tissues of transgenic fish.(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   
108.
居住环境与绿化设计   总被引:6,自引:0,他引:6  
居住区环境设计是一门新兴的学科。其规划理论需要进一步提高和丰富。为了创造舒适、方便、安全、卫生、美观的居住区和提供生活、休息、娱乐的优美环境,居住区环境设计即成为综合性新学科。居住区绿化设计的目的是要保持和利用原有地形、地貌,形成丰富的空间,要因地制宜,随坡就势,运用造园手法,组织各有特色的住宅组团,形成生活方便、环境优美的居住新村。本文就居民区空间功能的划分、住宅庭院绿化的布置进行了阐述,同时对居民区绿化的树种选择进行了说明。  相似文献   
109.
110.
During the past few years, several methods have been developed for the detection of specific nucleic acid sequences by in situ hybridization using non-radioactive labels such as fluorochromes, cytochemically detectable enzymes and electron-dense markers. These methods are preferable to autoradiography in terms of speed of performance and topological resolution. Their limited sensitivity, however, has so far restricted their use to the detection of repeated sequences. Here we report single gene detection with a procedure using 2-acetylaminofluorene (AAF)-modified probes, immunoperoxidase cytochemistry and reflection-contrast microscopy. We confirmed the autoradiographic data on the localization of the human thyroglobulin (Tg) gene to the distal end of the long arm of chromosome 8. A mixture of cosmid cHT2-derived subclones of the 3' part of the Tg gene, 22.3 kilobase pairs (kbp) in total, was used as a hybridization probe. This procedure can be used to map other unique sequences, if genomic clones are available from which clones with an appropriate amount of inserts can be isolated.  相似文献   
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