盐胁迫下施肥对棉花生长及氮素利用的影响

利用海水配制不同含盐量(0、0.15%、0.3%)的土壤盆栽棉花,在可移动遮雨棚内研究了不同施肥(N、NK、NP、NPK)处理对棉花生长、氮素吸收与利用的影响.结果表明: 盐胁迫和施肥均影响棉花生物产量、棉株氮素农学利用效率、氮素生物利用效率和氮素积累量,且两者存在显著的互作效应.施肥能提高盐胁迫下棉株氮素利用效率及氮素积累量,并显著增产,不同施肥处理中以N、P、K肥料配合施用的效果最好;施肥效果受盐胁迫程度的影响,低盐胁迫(0.15%)下的施肥效果好于中度盐胁迫(0.3%).     

干旱胁迫与复水过程中遮光对细叶小羽藓的生理生化影响

以细叶小羽藓为试材,分别设置全光照、遮光30％、遮光50％和遮光70％条件,采用人工控水方法研究了干旱胁迫与复水过程中细叶小羽藓的质膜透性、渗透调节能力及抗氧化酶系统的变化.结果表明:于旱胁迫过程中,细叶小羽藓的相对含水量呈下降趋势,而相对电导率在干旱21 d时达到最大值,且全光照下的相对电导率最高(58.0％);可溶性糖和游离脯氨酸含量均先上升后下降;超氧化物歧化酶(SOD)和过氧化物酶(POD)活性先持续上升而后下降.在复水过程中,细叶小羽藓的相对含水量与干旱胁迫时相反;相对电导率、可溶性糖含量、游离脯氨酸含量、SOD和POD活性先小幅回升后逐渐下降,但SOD和POD活性仍较高;复水后大部分指标都恢复到干旱胁迫前水平.细叶小羽藓具备复苏植物的典型特征,在变水过程中有较强的抗旱能力.     

不同配置模式下油蒿和柠条对降雨变化的生理生态响应及调节机制

研究了沙坡头地区固沙植物油蒿和柠条在1 m×1 m和2 m×2 m配置模式下的群落学特征,以及在自然和控制降雨条件下的水分关系、气体交换及其调节机制.结果表明:随着土壤含水量的变化,油蒿和柠条的生理耗水和生长特性不同,油蒿的气孔导度、水势、蒸腾速率、光合速率和快速生长均呈现明显的波动性,并且对土壤水分的消耗量高于柠条;柠条的上述指标变化相对低缓而恒定,光合生长速率较低,多年累积生物量却很高.两种植物对水分胁迫的响应过程和调节机制不同,油蒿主要为保水机制,柠条主要为节水机制.在极端干旱年份,柠条的节水、抗逆特性更强.固沙植物种的选择应既利于防风固沙和节约用水,又利于固沙林的稳定.     

高中生物课堂教学的有效策略研究

新课程改革为高中生物课堂的教学提出了新的挑战,如何从教师的备课开始,到如何安排课堂结构,以及如何运用课堂语言,激发学生学习生物的兴趣,培养学生自主学习能力,构建和谐的师生关系,运用好课堂评价这些有效策略,来提高学生学习的效果,这是每一位高中生物教师亟待解决的问题。本文就此进行探讨与研究。     

新课改背景下初中生物课堂有效教学策略探讨

随着素质教育改革的不断深入,建设有效课堂成为现代教育所追求的重要目标。作为初中阶段一门非常重要的学科,生物课堂的有效教学建设是必然的趋势。本文主要介绍了在新课改背景下建设初中生物课堂有效教学的策略。     

在用医疗器械风险管理问题探讨

随着医学的不断发展,人们对医学的重点度也在不断提高,随之而来的就是对医疗器械的应用,作为医学进步的辅助手段,医疗器械发挥着不容忽视的作用。本文将对在用医疗器械风险管理问题进行研究,希望可以进一步促进在用医疗器械风险管理效率的提高。     

干旱复水对海棠叶片光合蒸腾及水分利用效率的影响

以13个类型的盆栽海棠为材料,分析了自然干旱及旱后复水时叶片净光合速率(net photosynthesis rate,Pn),蒸腾速率(transpiration rate,Tr)及水分利用效率(water use effi ciency,WUE)。结果表明:13个海棠中,西府海棠的Pn和WUE最低,对水分变化最不敏感;平邑甜茶比较适应轻度和中度干旱,不适应重度干旱。复水后‘紫色王子’、‘绚丽’和‘雪球’等9个类型的Pn明显超过原初状态;‘红艳’、‘糖美林’、‘红粉’、‘红宝石’和‘王族’通过提高WUE来抵抗干旱胁迫,‘绚丽’、‘红丽’和垂丝海棠通过维持较强的恢复能力适应抗旱。干旱时,‘绚丽’比其他海棠能够更高效地利用水分。     

Effects of groundwater salinity on the characteristics of leaf photosynthesis and stem sap flow in Tamarix chinensis

AimsThe objective of this study was to investigate the change pattern of leaves photosynthesis and stem sap flow of Tamarix chinensisin under different groundwater salinity, which can be served as a theoretical basis and technical reference for cultivation and management of T. chinensis in shallow groundwater table around Yellow River Delta.MethodsThree-year-old T. chinensis, one of the dominated species in Yellow River Delta, was selected. Plants were treated by four different salinity concentrations of groundwater—fresh water (0 g∙L^-1), brackish water (3.0 g∙L^-1), saline water (8.0 g∙L^-1), and salt water (20.0 g∙L^-1) under 1.2 m groundwater level. Light response of photosynthesis and the diurnal courses of leaf transpiration rate, stem sap flux velocity and environment factors under different groundwater salinity were determined via LI-6400XT portable photosynthesis system and a Dynamax packaged stem sap flow gauge based on stem-heat balance method, respectively.Important findings The result showed that groundwater salinity had a significant impact on photosynthesis efficiency and water consumption capacity of T. chinensis by influencing the soil salt. The net photosynthetic rate (P_n), maximum P_n, transpiration rate, stomatal conductance, apparent quantum yield and dark respiration rate increased first and then decreased with increasing groundwater salinity, while the water use efficiency (WUE) continuously decreased. The mean P_n under fresh water, brackish water and salt water decreased by 44.1%, 15.1% and 62.6%, respectively, compared with that under saline water (25.90 µmol∙m^-2∙s^-1). The mean WUE under brackish water, saline water and salt water decreased by 25.0%, 29.2% and 41.7%, respectively, compared with that under fresh water (2.40 µmol∙mmol^-1). With the increase of groundwater salinity from brackish water to salt water, light saturation point of T. chinensisdecreased while the light compensation point increased, which lead to the decrease of light ecological amplitude and light use efficiency. Fresh water and brackish water treatment helped T. chinensis to use low or high level light, which could significantly improve the utilization rate of light energy. The decrease in P_n of T. chinensis was mainly due to non-stomatal limitation under treatment from saline water to fresh water, while the decrease in P_n of T. chinensis was due to stomatal limitation from saline water to salt water. With increasing groundwater salinity, stem sap flux velocity of T. chinensis increased firstly and then decreased, reached the maximum value under saline water. The mean stem sap flux velocity under fresh water, brackish water and salt water decreased by 61.8%, 13.1% and 41.9%, respectively, compared with that under saline water (16.96 g·h^-1). Tamarix chinensis had higher photosynthetic productivity under saline water treatment, and could attained high WUE under severe water deprivation by transpiration, which was suitable for the growth of T. chinensis.     

医药 CRO 专题报告——蓝海市场，强者恒强

随着全球制药企业研发投资成本加大、研发周期变长、研发成功率降低,作为社会分工专业化的产物,CRO 企业凭借其低成本、高效率、 多服务的特点,快速发展,且服务范畴已涵盖药物研发的整个过程,成为医药研发产业链中不可缺少的环节。报告采用文献调研、数据库检索、 数据统计与分析等定性定量研究方法,从发展概况、发展策略、竞争格局、企业布局等角度对国内外医药 CRO 领域进行多角度、多层次的 分析,旨在为相关企业确定产品研发思路、制定市场策略提供线索和参考。     

毕赤酵母GS115表达HSA-GCSFm的诱导工艺研究

本文探讨了甲醇流加控制、添加胰蛋白胨和甲醇/山梨醇共混诱导对重组毕赤酵母GS115/pPIC9K-HSA-GCSFm表达HSA-GCSFm的影响.结果显示:甲醇供应充足条件下HSA-GCSFm表达水平仅为37 mg·L-1,而甲醇添加受限条件下HSA-GCSFm表达水平可达到239mg·L-1;甲醇添加受限并添加胰蛋白胨条件下,HSA-GCSFm表达水平可以提高到266 mg·L-1;在此基础上,流加山梨醇作为辅助碳源,表达水平可大幅提高至424 mg·L-1.通过对各诱导条件下OUR、胞外蛋白酶及碳流分配进行分析后发现,将甲醇限制在低浓度同时添加胰蛋白胨与山梨醇,可以改善细胞代谢活性,增加细胞用于HSA-GCSFm合成的碳流分配量,降低胞外蛋白酶活性,从而提高了HSA-GCSFm的表达水平并缓解了HSA-GCSFm的降解.因此,该诱导工艺适于毕赤酵母高效表达HSA-GCSFm.