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关键词： 血液循环   生物学教学   脊椎动物  

摘要： 从1996年我校初创时,学校即着手组织队伍积极研制开发多媒体教学课件,并将它用于课堂教学,提高了课堂教学的效率,取得了初步成效.今就生物学科研制的《脊椎动物五纲血液循环》课件在教学中的应用成效,谈一谈多媒体技术在中学生物学教学中的应用及其作用.

关键词： nucleoside transporter   equilibrative   concentrative   ENT   CNT  

摘要： Nucleosides are hydrophilic molecules and require specialized transport proteins for permeation of cell membranes. There are two types of nucleoside transport processes: equilibrative bidirectional processes driven by chemical gradients and inwardly directed concentrative processes driven by the sodium electrochemical gradient. The equilibrative nucleoside transport processes (es, ei) are found in most mammalian cell types, whereas the concentrative nucleoside transport processes (cit, cif, cib, csg, cs) are present primarily in specialized epithelia. Using a variety of cloning strategies and functional expression in oocytes of Xenopus laevis, we have isolated and characterized cDNAs encoding the rat and human nucleoside transporter proteins of the four major nucleoside transport processes of mammalian cells (es, ei, cit, cif). From the sequence relationships of these proteins with each other and with sequences in the public data bases, we have concluded that the equilibrative and concentrative nucleoside transport processes are mediated by members of two previously unrecognized groups of integral membrane proteins, which we have designated the equilibrative nucleoside transporter (ENT) and the concentrative nucleoside transporter (CNT) protein families. This review summarizes the current state of knowledge in the molecular biology of the ENT and CNT protein families, focusing on the characteristics of the four human (h) and rat (r) nucleoside transport proteins (r/hENT1, r/hENT2, r/hCNT1, r/hCNT2).

关键词： 饲养密度   动物福利   动物安宁   畜禽饲养   生理需求   猪舍   畜禽舍   动物生理   动物生物学   生物学特点  

摘要： 目前,在世界范围内,正兴起一场畜禽饲养工艺改革的浪潮,即根据动物生理、行为、刃性、环境等生物学特点,通过动物福利技术设施的研究及实施,达到改善养殖条件,满足动物生物学要求,从而达到增产增值,提高饲养密度,提高肉品质品位的目标。户外养猪和猪村养猪工艺就是其中比较突出的例子,在欧美

关键词： 定义   检测   水平的   试验媒体   方法   试验   细菌计数方法   微生物   农产品   微生物分析   食品   计数   饲料   细菌纲   微生物学   介质   抽样方法  

标准号: DIN EN ISO 11290-2-1998

关键词： 试验   食品检验   食品检验   微生物   微生物分析   检测   乳酸菌   肉制品   微生物学   饲料   食品   农产品   基准方法   肉食分析   细菌纲   动物产品   计数方法(微生物学)   乳酸   家禽   微菌落计数   菌落计数技术   刮刀法   细菌计数方法   肉   刮勺(实验室)   定义   好气菌  

标准号: ISO 15214-1998

摘要： This International Standard specifies a horizontal method for the enumeration of viable mesophilic lactic acid bacteria by counting the colonies growing in a solid medium after incubation at 30 ℃ for 3 days. NOTE In some food products, there exist psychotrophic or thermophilic lactic acid bacteria necessitating culture temperatures different from 30 ℃. Moreover, not all lactic acid bacteria grow on MRS agar at pH 5,7 and some grow only weakly. Subject to the limitations discussed in the introduction and in the note above, this International Standard is applicable to products intended for human consumption or animal foodstuffs.

关键词： 检测   饲料   细菌计数方法   微生物学   细菌纲   微生物分析   定义   微生物   农产品   试验   食品  

标准号: ISO 11290-2-1998

摘要： This part of ISO 11290 specifies a horizontal method for the enumeration of Listeria monocytogenes. NOTE — The method also allows enumeration of other Listeria species which may be used as indicators of the hygienic quality of food or feed products. Subject to the limitations discussed in the introduction, this part of ISO 11290 is applicable to products intended for human consumption or animal foodstuffs. In general (see note in 9.2.1), the lower limit of enumeration of this method is 10 L. monocytogenes per millilitre of sample for liquid products, or 100 L. monocytogenes per gram of sample for other products.

摘要： The biology of Natatolana borealis, a deep-sea (-500 m) scavenging isopod that lives on the continental slope of Mediterranean canyons, was studied in the field and in the laboratory. Animals were collected at two stations using a baited trap. Whatever the site at which the animals were collected, a strong correlation was always found to exist between their length and weight, which shows variably marked seasonal variations. The growth pattern was modelled by fitting the Von Bertalanffy growth equation to the length of animals of various ages. The lifespan was estimated to be 6 years in the case of the largest animals collected. Sexual maturity is presumably reached at the age of 2.5 years. Not all the females were found to be sexually active at the same period of the year. A scheme of reproductive cycle is proposed for the mature females. It seems likely that each female may produce at least four broods during her lifetime. The emergence of offspring occurs at various times throughout the year, resulting in successive cohorts. At some periods in the year, some developmental stages were lacking in the samples, possibly owing to alimentary behaviour that helps to protect the animals from predators. (C) 1998 Elsevier Science Ltd.

关键词： Tigriopus   differential scanning calorimetry   supercooling point   melting point   subzero survival   osmoconformer   supralittoral rockpools  

摘要： Cold-resistance studies of marine invertebrates have concentrated on intertidal sedentary organisms, which are often subjected to subzero air temperatures in winter. Mobile rock Fool inhabitants have been rarely studied because such habitats are thought to buffer environmental variation. However, it is not uncommon for small upper-shore rock pools (similar to 2 by 1 cm) to become completely frozen. Such supralittoral habitats art subject to extreme physicochemical fluctuations especially in salinity (0 to 300 parts per thousand) and temperature (-1 to +32 degrees C) due to evaporation and dilution. The dominant invertebrate in such habitats is the harpacticoid copepod Tigriopus brevicornis. Aspects of the cryobiology of T. brevicornis were investigated using differential scanning calorimetry (DSC). Thermograms obtained from DSC allowed determinations of freeze-onset (supercooling point, SCP), melt-onset, and melt-peak (melting point, MP) temperatures, together with estimation of the proportion of water freezing in the samples. The effects of acclimation salinity, temperature, starvation, and reproductive state on these cryobiological parameters were investigated. Acclimation to increasing salinity depressed the SCP,with the highest salinity (70 parts per thousand) producing the lowest SCP, melt-onset, and MP temperatures at -27.5, -15.2, and -9.5 degrees C respectively. The highest acclimation temperature (20 degrees C) produced the lowest SCP (-23.4 degrees C). Starvation significantly increased the SCP, melt-onset, and MP temperatures in comparison to fed individuals acclimated to the same salinity. The presence of eggs or ovaries in individual copepods elevated the SCP compared to nongravid females and males. LT50 studies showed that acclimation to high salinity improved the ability of T. brevicornis to survive in frozen seawater. Seventy parts per thousand acclimated individuals had an LT50 of 64.9 h compared with just 1.4 h for 5 parts per thousand acclimated i

摘要： Leptocheirus pinguis (Stimpson, 1853) is a widely distributed, abundant, endobenthic amphipod that engages in extended parental care, i.e. females host their juveniles in their burrows for extended time periods. I examined reproduction and population biology of L. pinguis at mean low water (MLW) in muddy sediment in Lowes Cove, Maine, USA. Cores around individual burrows were taken monthly in 1994 and 1995, and four seasonal samples were taken at different tidal heights. During the major reproductive periods in spring/early summer and in the fall, females produced several consecutive broods and hosted growing offspring in their burrows. Juveniles remained in their mothers' burrows until they reached a length of 5 mm (approximately one-third adult size) or more. At the study site, the majority of amphipods in individual burrows were adult females. Following the main reproductive periods, subadult individuals were found in their own burrows, but densities did not increase following the reproductive period in spring/early summer 1994, probably because large numbers of L. pinguis emigrated via the water column between June and December. L. pinguis is an annual species. Many members of the cohort born in spring/ early summer start reproducing in the fall, and survive until the following spring when they produce several broods. Members of the cohort born in the fall start reproducing the following spring and also produce several consecutive broods. Both the spring/early summer and fall cohorts die off after the major reproductive period in the following spring/early summer. High standing stocks of microphytobenthos occur in soft-bottoms at MLW, and I conclude that L. pinguis can engage in extended parental care there because its food is abundant year-round. The limited expandability and low stability of burrows in soft-bottoms at MLW do not permit long persistence of parent-offspring groups in L. pinguis.

关键词： 动物   分类系统   生物工艺学   微生物   文献索引   家用的   英国   病毒   法规   寄生物   荷兰   生物技术   德国   比利时   真菌门   法国   病原体   微生物学  

标准号: PD 6613-1997