壬基酚对黑斑蛙神经活动的影响

应用电生理的方法研究不同浓度壬基酚对黑斑蛙的坐骨神经干神经冲动产生和传导的影响。用不同浓度的壬基酚处理黑斑蛙,7 d后,观察其活动状态和体表特征,同时用生物信号采集处理系统分别测定壬基酚对黑斑蛙坐骨神经干的神经冲动传导速度、动作电位幅度、相对不应期和绝对不应期的影响。结果表明：随着壬基酚浓度的增加,黑斑蛙的活力减弱,其皮肤出现血斑的现象加重,说明壬基酚可引起黑斑蛙活力、精神和体表等发生异常;随着壬基酚浓度的升高,黑斑蛙坐骨神经干的神经冲动传导速度逐渐减慢,动作电位峰值降低,相对不应期和绝对不应期逐渐延长,与壬基酚浓度呈剂量-效应关系。说明在壬基酚作用下,黑斑蛙神经活动对刺激反应的灵敏性降低,动作电位的产生及传导受到一定程度的抑制和阻碍。在50 mg·kg^-1低浓度组,壬基酚对黑斑蛙神经活动影响不显著(P>0.05),说明黑斑蛙对低浓度的壬基酚有一定的耐受力。     

绿洲农业不同种植方式防止土壤风蚀和保持土壤水分的比较

2001年～2002年,在河西走廊中断黑河中游,研究了不同方式对春季就地起沙、风速梯度、水分保持等方面的效应．结果表明,冬灌免耕、粮草间作和早春覆膜措施都不同程度地遏制了就地起沙,减少了土壤风蚀．早春覆膜在减少土壤风蚀量的同时,提高了土壤蓄水量,比春耕裸露农田蓄水量增加了35．6％．目前．春耕播种裸地是形成沙尘暴和浮尘的粉尘含量的主要来源之一,黑河中、上游农田耕地每年产生的粉尘输移量达4．8×10^6～6．0×10^6t,高于同区域沙漠粉尘输移量．河西走廊粉尘输移量1hm^2农田相当于1．5hm^2沙漠．     

新疆绿洲杨树的生理生态学研究展望

绿洲是一类独特的生态系统,它具有独特的结构和功能。杨树是构成新疆绿洲防护林体系的主要树种。本文在对策勒绿洲杨树生理生态学特性研究的基础上,从水分生理和光合作用两方面对国内外研究杨树生理生态学特性的一些方法和手段进行了初步评述,以期这项工作在独特的绿洲系统内广泛开展,从而为优选绿洲防护林树种、优化防护林体系及确保绿洲的可持续发展提供一定的理论依据。     

Stratigraphy and microfacies of the oligocene sequence at Gabal Bu Husah, Marada Oasis, South Sirte Basin, Libya

Summary Stratigraphic and microfacies investigations carried out on the Oligocene sequence exposed at Gabal Bu Husah, northwest of Marada Oasis, south of the Sirte Basin, Libya, showed that the Oligocene sequence conformably overlies the Late Eocene Thamat Formation and unconformably underlies the Early to Middle Miocene Marada Formation (Qarat Jahannam Member). The lithostratigraphic studies of the Oligocene sequence revealed the presence of two rock units, from base to top: 1- Umm Ad Dahiy Formation (Early Oligocene, Rupelian) and 2- Bu Hashish Formation (Late Oligocene, Chattian). The Oligocene sequence yields a rich foraminiferal assemblage with fifty-one benthonic and large formaminiferal species. The foraminiferal analysis allowed to subdivide the sequence into three local foraminiferal assemblage zones, arranged stratigraphically from base to top: 1)Elphidium minutum zone comprising the Umm Ad Dahiy Formation. 2)Miogypsinoides complanatus/Nonion granosus assemblage zone covering the lower two thirds of the Bu Hashish Formation. 3) Zone with abundantNummulites spp., including the upper part of the Bu Hashish Formation. The paleoenvironmental significance of the recorded species is described and discussed. The microfacies studies led to the recognition of eleven microfacies types. These microfacies indicate that the lower part of the Umm Ad Dahiy Formation was deposited in a shallow warm marine environment, but the conditions changed to fluviomarine in the uppermost part. The Bu Hashish Formation was deposited in a shallow-marine, inner-shelf environment (as indicated by the operculinid limestone) but a probable hiatus in its middle part is indicated by the presence of a nummulitic coquina and gypsum beds formed in a lagoonal environment. After returning to a shallow marine environment at the end of Oligocene the marine sedimentation ended.     

基于不同样带的干旱区城市景观格局时空演变特征——以张掖市为例

景观格局的变化影响着区域生态安全及可持续发展，研究干旱区城市景观格局时空变化特征，对干旱区景观格局优化具有一定的指导意义。基于1987、1995、2000、2006、2011和2016年6期土地利用数据，利用景观格局指数计算方法，研究张掖市景观格局的时空演变特征。结果表明：(1)2016年张掖市景观类型主要为未利用地，最大斑块指数和斑块聚集度最高，草地和耕地次之，草地的斑块个数和密度最大。(2)张掖市景观格局呈现明显的地域分异特征，圈层梯度带上揭示了绿洲-荒漠用地变化，研究期内第1梯度带内破碎度先上升后下降，城市在2006—2016年扩张较快，其余梯度带破碎度逐年升高；空间演变上，居住地在圈层上的变化呈“L”型，未利用地呈“N”型，张掖市从中心城区到外围区域依次为绿洲城市区、绿洲农业区和自然景观区。(3)水平样带揭示了山地-绿洲-荒漠的用地变化，将张掖市分为4类区域，分别为绿洲城市区、绿洲农业区、荒漠区、山地区；西北-东南样带上景观破碎度年变化不规律，在空间上经过居民点波动变化；东北-西南样带研究期内景观水平指数经过居民点波动变化，其余范围内年变化较稳定，中心城区景观异质性较强。(4)...     

Usage of agricultural DAP-fertilizer and Eucalyptus essential oils as potential attractants against the mediterranean fruit fly Ceratitis capitata (Tephritidae)

In Tunisia, oasis ecosystem is characterized by fragility due to the abusive application of insecticides and fertilizers. Moreover, in oasis Ceratitis capitata is a major pest. Its control relied on synthetic pesticides. This work aims to assess the efficiency of the two formulations based on the combination of DAP and Eucalyptus essential oils. X-Ray Diffraction and Brunauer-Emmett-Teller surface area were used to characterize DAP fertilizer. GC–MS analysis were performed for analyze oils composition and adsorption of oil compounds. Kinetics adsorption/desorption was determined by measuring the mass of solid samples over time. Repellent/attractant and contact toxicity tests of Eucalyptus cinerea and E. maidenii oils and their formulations were evaluated against Medfly adults. GC–MS analysis indicated that 1,8-cineole was the dominant major common compound (E. cinerea: 74.58%, E. maidenii 66.70%). Moreover, the adsorption efficacy depends on the abundance of each compound in crude essential oils and the polarity of terpenic components. Indeed, percentage of 1,8-cineole adsorption in the formulation was 76.15%for E. cinerea and 65.24% for E. maidenii. Results indicated the attractant potential of both essential oils (class III) and that DAP/essential oils formulations accomplished better attractant performance (class IV). Besides, formulations were toxic towards C. capitata adults (80% and 100% mortality for E. cinerea and E. maidenii). Results pointed out that the commercial lure Ceratrap®, traps baited with DAP/E. maidenii and DAP/E. cinerea formulations were attractant against C. capitata adults under field conditions. This work supports the use of essential oils and fertilizers-based formulations as an innovative tool for the management of Medfly.     

Assessment of farmers practices to date palm soil fertilization and its impact on productivity at Al-Hassa oasis of KSA

Al-Hassa oasis is considered as the biggest irrigated one in the World, being well known for its extensive date palm cultivation with an estimate of at least three million trees. The aim of this study is to evaluate the impact of soil fertilization practices on the productivity potential of date palm trees grown under the climatic conditions of Al-Hassa oasis, KSA. The opinions of 258 active farmers were randomly surveyed using specifically designed questioners that were also fortified with personal communications. The size of the samples was designated in accordance to Cocoran equation. The total samples were allocated into two major parts (193 for the old oasis and 65 for the new oasis). Results showed that the farm features (utilized agricultural area (UAA), ownership and labors) are different in both parts of the oasis. Fertilization practices (quantity applied per area or per tree) were diverse causing dissimilar productivity potentials (total or per area or tree). The average production of a tree in the old oasis is 81.4 kg, whilst it is 54.6 kg in the new oasis. Date palm production is significantly affected by total number of trees, applied fertilizer quantity, cultivated area and labor power. The impact of these factors is unlike between the two parts of the oasis. It is then concluded from the study that there are sincere needs for improving the soil fertilization practiced for the date palm trees grown in the Al-Hassa oasis, KSA in order to increase their productivity potential and hence improve the farmers' income.