镉胁迫对罗汉果幼苗生理生化特性的影响

[目的]研究不同浓度Cd胁迫对罗汉果幼苗生理生化特性的影响.[方法]通过盆栽试验,测定不同浓度Cd处理的罗汉果幼苗细胞膜透性,MDA、脯氨酸和可溶性糖含量,以及SOD、POD、CAT活性等各项生理生化指标.[结果]随着Cd浓度升高,细胞膜透性逐渐增大;在相对低浓度Cd(10 mg/kg)处理下 MDA、脯氨酸和可溶性糖含量均少于对照,而后随着Cd浓度的升高而明显上升;在较低Cd浓度胁迫条件下,SOD、POD、CAT活性变化不明显,但随着Cd浓度的升高,SOD、POD、CAT活性逐渐升高,然后又降低.[结论]高浓度Cd胁迫加重了叶片氧化程度并对罗汉果生长具有一定的抑制作用;而SOD、POD、CAT 活性的提高与维持是罗汉果耐Cd 胁迫的物质基础之一.     

PEG渗透胁迫下玉米幼苗叶片保护酶活性昼夜变化

[目的]了解逆境条件对植物体内保护酶活性昼夜变化的影响.[方法]用不同浓度聚乙二醇(PEC-6000)溶液研究渗透胁迫下玉米幼苗叶片电解质外渗率、丙二醛(MDA)含量和超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)的昼夜变化情况.[结果]一昼夜胁迫中,保护酶活性的变化不仅受PEG浓度和胁迫时间的影响,而且受先照的影响.随着光照时间和胁迫时间的延长,叶片电解质外渗率和MDA含量增加、SOD活性持续降低、POD和CAT活性的变化率则呈先增加后降低趋势;先照结束后,随着黑暗时间的延长,电解质外渗率和保护酶活性先接近对照水平,然后发生较大渡动.[结论]玉米幼苗叶片的保护酶活性变化不仅受PEG浓度、胁迫时间的影响,而且受光照的影响.     

Cu2+、Cd2+、Cr6+胁迫对斑马鱼抗氧化酶活性的影响

[目的]研究Cu<'2+>、Cd<'2+>、Cr<'6+>对斑马鱼抗氧化酶活性影响,探讨重金属对斑马鱼毒性大小.[方法]以斑马鱼为模式生物,采用半静态法对斑马鱼进行驯养和试验,测定Cu<'2+>、Cd<'2+>和Cr<'6+>对超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性影响.[结果]Cu<'2+>暴露1d胁迫斑马鱼SOD和CAT为诱导效应,胁迫POD为抑制-诱导-抑制效应,Cu<'2+>暴露7 d胁迫斑马鱼SOD为诱导效应,胁迫POD和CAT为抑制效应;Cu<'2+>和Cr<'6+>暴露1 d和7 d胁迫斑马鱼SOD和CAT均为诱导效应,胁迫POD为抑制效应.且暴露1 d和暴露7 d酶活性变化均显著.[结论]Cu<'2+>、Cd<'2+>、Cr<'6+>单一胁迫斑马鱼抗氧化系统酶活性变化显著,在短时间和低浓度暴露下,Cr<'6+>毒性作用最显著;在短时间中、高浓度暴露下,Cu<'2+>毒性作用最显著;长时间暴露时,Cu<'2+>毒性作用最强,可为重金属污染对水生生物毒性机理研究提供参考.     

Cr6+和Pb2+重金属胁迫对大蒜发芽的影响

[目的]研究Cr<'6+>和Pb<'2+>胁迫对大蒜发芽的影响.[方法]测定了在Cr<'6+>和Pb<'2+>种重金属胁迫下大蒜发芽过程中的根长、酶(SOD和CAT)活性及可溶性蛋白质含量.[结果]大蒜萌发过程中,Cr<'6+>和Pb<'2+>重金属浓度超过20 mg/L时对芽苗根长有明显的抑制作用;SOD和CAT对低浓度的重金属毒性具有一定的缓冲能力,在低浓度Cr<'6+>胁迫下SOD活性随着金属离子浓度的增加而增大,且当处理浓度为50 mg/L时达到最大,而CAT活性在Cr<'6+>浓度低于20 mg/L时逐渐增大;SOD和CAT活性在高浓度Cr<'6+>(大于50 mg/L)或在Pb<'2+>胁迫下随重金属离子浓度的增加而持续降低;在重金属(Cr<'6+>、Pb<'2+>)溶液各个浓度作用下随着时间延长可溶性蛋白质含量均表现出下降趋势,且随着浓度的提升下降趋势明显.另外,大蒜对Cr<'6+>毒性的耐受性远高于对Pb<'2+>.[结论]为深入探讨重金属对植物的毒害机制提供了理论依据.     

铅胁迫对紫萼玉簪幼苗SOD,POD和CAT活性的影响

[目的]研究铅对紫萼玉簪幼苗的毒害机理,为园林植物铅污染的预测预报以及相关修复措施的提出等提供理论依据.[方法]采用温室砂培盆栽试验,通过在盆栽沙子中浇施铅溶液的方法,研究了不同浓度(0、125、250、500、1 000、2 000 mg/kg)外源重金属铅对紫萼玉簪幼苗叶片抗氧化酶的影响.[结果]紫萼玉簪幼苗叶片SOD、CAT活性随铅胁迫浓度的升高呈现先升高后降低的趋势,POD活性随着铅胁迫浓度的增加而逐渐增强,且始终表现出较高的活性.SOD活性在2 000 mg/kg处理下仅为对照的1.55倍;CAT活性在2 000mg/kg处理下达到最低,与对照持平;而POD活性则在2 000 mg/kg处理下达到最大值,是对照的1.72倍.[结论]CAT是对高浓度铅毒害相对敏感的指标,它的敏感性高于POD,也很可能高于SOD.     

外源亚精胺对盐胁迫下小麦幼苗生长的影响

[目的]为了解亚精胺是否能缓解盐胁迫对小麦幼苗生长的影响.[方法]采用滤纸培养法,研究了外源亚精胺(Spd) 对NaCl 胁迫下小麦幼苗生长和部分生理指标的影响.[结果]与对照相比,盐胁迫抑制了小麦幼苗的生长,增加了小麦中SOD、POD活性和MDA含量,降低了可溶性蛋白质含量.亚精胺处理明显促进了小麦幼苗的生长,提高了幼苗中SOD和POD活性,降低了MDA含量,提高了可溶性蛋白质含量.[结论]亚精胺能缓解盐胁迫对小麦幼苗的毒害作用,提高小麦幼苗的抗盐能力,但随处理时间的延长,亚精胺的缓解作用有所下降.     

外源水杨酸对番茄耐盐性的影响

[目的]探讨外源水杨酸(SA)对番茄耐盐性的影响,为SA在番茄生产中的应用提供理论依据.[方法]在盐胁迫条件下,对番茄喷施不同浓度(1、2、5 mmol/L)的SA,测定其叶片叶绿素含量、可溶性糖含量、过氧化物酶(POD)活性、相对电导率及根系活力,研究外源SA处理对番茄幼苗耐盐性的影响.[结果]外源SA能不同程度地提高番茄叶片叶绿素含量、可溶性糖含量、POD活性和根系活力,而降低叶片相对电导率.其中浓度2 mmol/L SA对叶绿素含量、POD活性和相对电导率的影响最佳,而浓度5 mmol/L SA对可溶性糖和根系活力的影响较大.[结论]外源SA能够提高番茄幼苗的耐盐性,但适宜施用浓度和施用周期尚需进一步研究.     

芘胁迫对玉米幼苗生长及生理指标的影响

[目的]探讨芘胁迫对玉米幼苗生长及生理指标的影响.[方法]通过水培试验,研究了4个浓度(0、0.5、1.0和2.0 mg/L)的芘对2种玉米市祥1号(敏感品种)和广甜3号(耐性品种)幼苗生长及生理指标的影响.[结果]在试验浓度范围内,随芘浓度的升高,市祥1号叶绿素a和叶绿素b含量呈先升高后降低的趋势,相对生长量和绝对生长速率呈下降趋势,根系和叶片丙二醛(MDA)含量呈上升趋势;广甜3号相对生长量、绝对生长速率和叶绿素a含量呈先上升后下降趋势,叶绿素b和根系MDA含量呈上升趋势,叶片MDA含量呈下降趋势.与对照相比,市祥1号在0.5～1.0 mg/L芘处理对叶绿素a和叶绿素b含量显著增加,芘浓度≥2.0 mg/L时则显著降低,芘浓度≥1.0 mg/L时根系和叶片MDA含量显著增加,而相对生长量和绝对生长速率显著降低;广甜3号在芘浓度≥1.0 mg/L时叶绿素a和叶绿素b含量显著增加.芘浓度与敏感品种市祥1号的相对生长量和绝对生长速率呈显著负相关,与根系MDA含量呈显著正相关;芘浓度与耐性品种广甜3号叶绿素b含量和根系MDA含量呈显著正相关.[结论]为玉米苗期的管理措施提供了依据.     

铈减轻铅对水稻幼苗毒害的机理初探

通过保护性酶活性及叶绿素、MDA含量的检测,根系活力及电导率测定研究铈减轻水稻幼苗抗重金属铅毒害能力的机理.结果表明,用适宜浓度Ce(NH4)2(NO3)6浸种后培养的幼苗,经重金属铅胁迫后,能有效地降低相对电导率,维持较高的SOD活性,提高POD、CAT活性,减缓MDA的积累.同时,能促进水稻幼苗叶绿素含量及根系活力的提高.     

SO2胁迫对茶条槭叶片6种保护酶活性的影响

[目的]研究不同SO<,2>胁迫处理对茶条槭叶片6种保护酶活性的影响.[方法]利用SO<,2>静态熏气系统时3年生茶条槭苗木进行胁迫处理,研究不同SO<,2> 浓度(0～6.0 mg/m<'3>)和熏气时间(0～6 h)下茶条槭叶片6种保护酶活性的变化趋势.[结果]随着SO<,2>浓度的增加,PPO和APX活性一直降低,SOD、CAT、POD和GR 活性表现为先迅速上升后下降的趋势,其中GR活性下降较平缓;在不同时间SO<,2>处理中,CAT和GR活性随着胁迫时间的延长先迅速上升而后下降,而SOD、POD、PPO和APX活性均随着胁迫时间的延长而降低,其中SOD和GR活性变化幅度较平缓.[结论]PPO、POD和APX活性下降可能是茶条槭幼苗SO<,2>伤害的原因之一,而SOD、CAT和GR活性变化平缓是茶条槭幼苗响应SO<,2>胁迫的适应性机制.     

Some fundamentals of B. F. Skinner's behaviorism.

Despite B. F. Skinner's prominence, his impressive written corpus, and the many authoritative presentations by others of his approach to psychology, the fundamentals of Skinner's psychology have never been addressed in any comprehensive manner. In this article, the authors take steps to fill this gap by synopsizing Skinner's written corpus into 12 fundamental points that seem to characterize his behaviorism. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Racemose angiomatosis. Comments on the article of D.E. Matsko and I.A.Sokolova. Racemose angioma of the nervous system: tumor or developmental defect? Vopr. onkol. 1966. V.42, No.6. p.91-96

Diversion colitis is thought to result from nutritional deficiencies secondary to fecal diversion. Symptoms include hemorrhagic purulent rectal discharge, abdominal pain, and tenesmus. 5-Aminosalicylic acid (5-ASA) and N-butyrate enemas have been reported to help this condition non-spinal cord injury (SCI) patients. We report the case of a 49-year-old C6 ASIA B tetraplegic man who had received colostomy because of intractable ileus 10 years earlier. He presented with a 2-week history of rectal pain and bleeding. Abdominal and rectal examination on admission were unremarkable. Colonoscopy showed a partial stricture 70cm proximally to the rectum. The colonic mucosa appeared granular and friable with evidence of linear ulceration. Histopathologic study was consistent with colitis. The patient developed fever, abdominal distention, and extensive retroperitoneal air after endoscopy, suggesting colonic perforation. He was treated with daily 5-ASA suppository and total parenteral nutrition for the presumed diagnosis of diversion colitis, and intravenous antibiotics for perforated colon. After 6 weeks of treatment with 5-ASA, the patient had decreased rectal pain and bleeding. This experience suggests that diversion colitis may be a cause of abdominal discomfort in SCI patients and that 5-ASA may be used in the management of diversion colitis.     

Educators' perceptions of the D.A.R.E. program

This study examines the perceptions of educators about the Drug Abuse Resistance Education (D.A.R.E.) program, based on the results of a statewide survey among 286 fifth and sixth grade teachers and principals. Educators gave their highest ratings to teacher/officer interaction, the role playing exercises, and the graduation ceremony. Ratings of overall program quality and the impact of the program on students were both high. Block regression analysis was used to examine factors predictive of educators' views of D.A.R.E. D.A.R.E. program elements were the most important factors explaining variance in educators' ratings of over-all program quality and program impact on students. Altogether, 54 percent and 38 percent of the variance in both dependent variables were explained. The results are discussed in terms of the important role teachers and principals play as stakeholders in prevention education.     

小方坯连铸机的切割设备

现在采用的小方坯连铸机的切割设备，分为机械剪和火焰切割机，机械剪包括电动机械剪和液压剪，而液压剪又有平剪刃和４５°剪刃之分，火焰切割机则分为有动力传动和无动力传动的火焰切割机，对这些切割设备的结构特点和优缺点均进行了分析介绍。     

Structural bonding contributions and the elastic response of b.c.c. and f.c.c. crystals

The anisotropic elastic response of body centered cubic (b.c.c.) and face centered cubic (f.c.c.) crystals is reviewed within the framework of general elasticity and particular model dependent relations. It is found that important trends in the observed behavior of specific groups of crystals can be reproduced by models that include only structural contributions to crystal binding. In fact, a very simple model, consisting of only nearest and next nearest neighbor interactions, reproduces the salient behavior, including the algebraic signs of Poisson's ratio and the orderings of the shear moduli, Young's moduli, and Poisson's ratios associated with major crystallographic symmetries. The analysis provides insight into the differences between the b.c.c. transition metals and the b.c.c. alkali metals.