甜瓜耐低温鉴定指标的研究

为了筛选出甜瓜芽期和苗期的耐冷鉴定指标,采用13份甜瓜材料,研究三个低温条件下的发芽能力、甜瓜幼苗在4℃低温下受害表现、恢复后的成活率及相对电导率,采用极点排序法对低温发芽能力综合评价并进行相关性分析;结果表明18℃下的相对发芽率、相对发芽势和相对活力指数在13份甜瓜中差异极显著(P＜0.05),与综合评价得分相关性都极显著,三个指标均可作为芽期的耐冷鉴定指标;4℃下处理3d后恢复3d的成活率与冷害指数相关性达到显著水平,可作为幼苗期耐冷差异鉴定指标,处理48h后相对电导率的增加也可用于苗期耐冷鉴定.     

水稻耐冷机理的研究进展

本文就近年来水稻耐冷机理的研究进展展开综述。内容包括:植物的冷敏感性可以通过调节膜脂的不饱和脂肪酸水平得到调控;水稻的抗氧化酶系统活性与其耐冷性有关;水稻低温信号转导的研究不断深入;低温下水稻碳同化酶活性的变化与水稻光合能力和耐冷性关系密切.     

H2O2处理对水稻不同耐冷品种幼苗叶绿素荧光参数的影响

采用10、100和1000μmoL／L H2O2溶液对水稻幼苗进行常温和低温的浸根处理,研究发现,常温下,耐冷品种中Fv／Fm、qP和西φPSII与对照比差异不显著,qNP增加,冷敏感品种中Fv／Fm基本维持对照水平, qP和西φPSII下降,qNP增加较多;低温下,10μmol/L H2O2处理12h,耐冷品种中叶绿素荧光各参数较对照增加, 不同浓度处理不会引起qNP的显著变化,但在冷敏感品种中,所有处理都会引起叶绿素荧光各参数较对照下降, 且随处理浓度增加和处理时间延长下降加剧。这些结果说明低温增加水稻对H2O2的敏感性,但文中不同H2O2处理对耐冷品种光合能力的影响较小,低温下10μmol／L H2O2处理甚至可以刺激水稻耐冷品种幼苗的抗冷性增加, 究其原因．可能与低温下耐冷品种体内可以保持较高的氧化酶活性有关。     

水稻芽期耐冷性主效QTLqSCT-11的分子标记定位

以粳籼交Lemont／Teqing的F13RILs群体为作图群体,构建水稻芽期耐冷性主效QTLqSCT-11所在染色体区段的高密度分子标记连锁图谱,用于主效QTLqST-11的分子标记定位与分析。通过测定粳籼交Lemont／Teqjng的RILs群体在10℃低温的芽期耐冷性,WinQTLCart2．5软件对耐冷性性状进行复合区间作图,结果表明此主效QTL位于11号染色体短臂近着丝粒区域ID7924-3与RM202标记之间。     

抗坏血酸和谷胱甘肽在小麦幼苗冷激诱导抗冷性中的变化

以小麦幼苗为实验材料，研究冷激及冷胁追处理过程中的抗坏血酸和谷胱甘肽含量变化，结果显示冷激处理小麦幼苗可导致还原型抗坏血酸和还原型谷胱甘肽的含量比对照组高，而脱氢抗坏血酸和氧化型谷胱甘肽的含量比对照组低．表明冷激处理可以使小麦幼苗细胞内抗坏血酸库和谷胱甘肽库中还原状态的抗坏血酸和谷胱甘肽含量明显增加，以有效地清除低温胁追产生的活性氧的危害，从而提高小麦幼苗的抗冷性．说明抗坏血酸和谷胱甘肽参与冷激诱导抗冷性的过程中起重要作用。     

低温胁迫下解放钟枇杷幼果细胞超微结构的变化

以解放钟枇杷幼果为试验材料,采用人工降温方法,研究低温胁迫下枇杷幼果超微结构的变化。结果表明:6℃、3℃低温胁迫时,解放钟果肉细胞质膜、液泡膜清晰,叶绿体、线粒体结构没有明显的变化;0℃低温处理条件下的原生质膜结构完整,少数叶绿体出现部分解体,双层膜有部分破裂现象,线粒体结构仍清晰可见;-3℃低温胁迫下,原生质膜、液胞膜均破裂,原生质体浓缩,叶绿体扭曲变形、相互融合,线粒体膜结构受损,脊消失。     

不同低温条件下微管稳定对大鼠供心冷藏损伤的影响

为研究不同低温条件下微管改变对大鼠供心保存冷缺血损伤的影响,将36只SD大鼠随机分成对照组(HTK液保存)和实验组(HTK液中含紫杉酚,浓度为10-6 M)。每组的18只SD大鼠再分成4℃、15℃和20℃条件下的3个不同低温保存组,每组6只,低温保存8 h,每间隔2 h灌注5 min。利用离体心脏非循环式Langendorff灌注模式装臵,观察经上述不同保存温度下保存8h后,复温再灌时的冠脉漏出液中心肌酶的含量,并切取心肌组织做光镜和电镜观察。结果显示随着保存温度升高,实验组和对照组中心肌细胞损伤加重,漏出酶增多;与对照组比较,4℃、15℃实验组复温再灌时的冠脉漏出液中乳酸脱氢酶含量明显减少,心肌细胞损伤较轻。说明4¹5℃深度低温条件下微管稳定剂能够减轻心肌的冷缺血损伤。     

基于应变片法的低温条件下热膨胀特征参数的测量方法与装置

研究目的：为了满足低温系统的材料选择和结构设计对于材料热膨胀特征参数的需求,研发低温条件下精确、快速、方便操作、低成本的热膨胀特征参数测量方法和系统装置。创新要点：完成了卡玛合金箔应变片在77-293K低温温区敏感系数的修正,保证了基于应变片技术的低温条件材料热膨胀特征参数测量的精度;所研制装置合理的热设计和等速率式温度控制模式使得材料热膨胀特征参数在77-293K温区的测量可在14小时内快速完成。研究方法：针对77-293K温区,基于应变片测量方法,研制了采用比例-积分-微分（PID）温控系统的固体材料热膨胀特征参数测量装置（见图2和3）。通过将304不锈钢的测量数据与美国国家标准与技术研究院（NIST）公布数据进行比较,完成了卡玛合金箔应变片存77-293K低温温区的敏感系数修正（见图7和8）。采用修正后的敏感系数进行无氧铜线性收缩率测量,并与NIST公布数据比较（见图9和表2）,验证了该装置在77-293K低温温区的测量精度。重要结论：获得了77-293K低温温区卡玛合金箔应变片敏感系数的修正结果;基于修正敏感系数的应变片法测量装置,采用0．3K／min的等速率式温度控制模式,可实现77-293K低温温区固体材料热膨胀特征参数的精确、快速测量。     

嗜冷酶及其耐冷机制

嗜冷酶是一类在低温条件下具有高催化活性的酶,也是低温微生物适应低温环境生存的重要条件.与嗜温酶相比,嗜冷酶一级结构的变化导致空间结构的变化,使酶分子的构象具有更大的柔性,同时也有利于这类酶在低温条件下需要更少的能量而发挥催化作用.     

低温有尽头吗?

1980年,德国科学家用液氦制得了接近-273.15℃的低温。这是当今世界人工创造的最低温度。它比宇宙的超冷区还要低3℃,人们不禁要问:低温有尽头吗?低温技术是人类智慧的结晶。18世纪,英国科学家汤姆生经过对气体物理性质的研究,得出-273.16℃是物质世界最低温度的推论。这是绝对零度的由来,也是物理学上K氏温标的起点。     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…     

库克斯顿城堡

城堡, 是欧洲典型的建筑之一, 每个城堡都有一个美丽的传说或是一段历史。从本期开始, 我们将推出“城堡之旅”, 带各位读者去浏览、观赏欧洲各地的城堡, 开始一段文化与历史的旅途!     

The Reader Response Approach to Teaching of English Literature

During interview with English majors, it was found that a majority of students expressed disappointment with their experience of English literature classes. Students' dislike of learning English literature appears to be the major problem of teaching English literature in China. Reader response approach is a good way to solve this problem. In this paper, I explain the rationale behind the reader response approach, such as its origin, definition, features, assumptions, and strategies. Then I illustrate how reader response approach works as a teaching strategy by presenting several teaching models. At last I evaluate its usefuiness for teachers and present the advantages of reader response approach in Chinese context.