Development and age‐related change of cerebrovascular noradrenergic (NA) innervation in the Japanese quail

Development of cerebrovascular noradrenergic (NA) innervation was investigated in the Japanese quail, using histofluorescence technique and quantitative analysis. Cerebral perivascular NA nerves arose from the cerebral carotid (CCA), internal ethmoidal (IEA) and vertebral (VA) arteries before hatching, with the first appearance on the CCA and IEA at embryonic day (E) 8 and of the VA at E14. Nerves arising from the IEA were greater in number and spread more rapidly than those from the CCA and VA. On E16, fluorescent fiber bundles lying on the anterior circulation subdivided rapidly into thin fibers. Consequently, the number of NA nerves over the arterial system increased greatly at hatching, particularly along the distal portion of the anterior ramus. At the same developmental stage, all the major arteries of the anterior and posterior circulation were almost entirely covered by NA nerves. The abrupt reorganization of cerebrovascular NA innervation in newborn quails may be related to some specific trophic and vasomotor roles for structural and functional improvement of the cerebral circulation that is required for its brain differentiation at this critical period of development. The supply of NA nerves to the anterior and posterior circulations sequentially increased during development from posthatching day (P) 1–15. Plexuses of NA nerves in each of the major cerebral arteries at P22 and P42–50 were similar in meshwork construction to each other, and to those seen at P15. Likewise, there was no clear statistical difference in the nerve density of the corresponding arteries among the three posthatching ages, except for the caudal basilar artery.     

Dynamic changes of a typical linear dune in the Tengger Desert

The dynamical processes of a typical linear dune including morphological features, dune ridge swing range and crest height were investigated at different monitoring periods in the hinterland of Tengger Desert. The results indicated that the development of linear dune depends on not only the northwesterly prevailing wind, but also the winds from northeast and southwest. The dune ridge swayed along its fundamental strike and took on an eastward movement gradually. The original dune strike was NW70° on August 3, 1994, and then changed to NE15° on April 21, 2001. The dune crest increased by 1.8 m longitudinally, which manifested strong wind-blown sand activities in this region. Wind erosion frequently occured at the bottom of sand dune, while sand accumulation appeared on its mid-upper section. The mean wind erosion depth was 25 cm on the bottom of linear dune and the height difference of the control points on the dune's ridge was 1.13 m. Although the linear dune swayed laterally, the horizontal displacement of its ridge moved eastward 5.8 m averagely. The swing range of the dune crest line is very distinct, with a maximum value of 13.2 m. The highest site on the K-profile swayed on both sides of the dune ridge and the heights were 19.88 m at the control point K5, 19.61 m at K6 and 19.05 m at K7, respectively. The results indicated that the lateral swing of the linear dune was distinct under the northwesterly wind and it moved toward east gradually.     

保持耕作下农药的环境行为

与传统耕作相比 ,管理措施中的保持耕作措施能减少农药随径流流失的量和增加淋溶量。本文分析了影响农药环境行为的机理 :提高土壤中有机质和水分含量可影响农药吸附性 ;提高入渗能力会增加农药淋溶量 ;增加蓄水保土效益可减少地表径流及农药流失     

博乐垦区土地利用/覆被变化及预测研究

基于博乐垦区1990年8月、2003年8月和2010年8月的3期TM影像数据,定量分析了研究区近20a土地利用/覆被的数量变化和空间变化,以及各地类质心的空间变化趋势。在此基础上,采用马尔科夫链方程预测了研究区未来10a(2015—2025年)土地利用/覆被的演变趋势。结果表明:近20a来,研究区的土地利用/覆被变化显著:(1)居民点用地大幅度增加,主要由草地和未利用地转化而来。林地大幅度减少,转化成了草地。耕地和草地先增加后减少,但总体呈增加趋势。水域面积略有减少;(2)各类用地的质心变化:1990—2003年,质心偏移幅度较小。除居民点用地外,其余地类都在10km以内。但2003—2010年,各类用地的空间质心都发生了较大的偏移;(3)在保持人为影响因素不变的前提下,未来10a(2015—2025年)垦区居民点用地、耕地和草地将继续增加,而水域、林地和未利用地将继续减少,但是各类用地的变化幅度都将减小。     

学生村官中“利己型创业者”的行为分析——基于苏北泗阳县和苏南无锡市的调查

大学生村官政策目前已成为我国一项重要的战略举措。通过对苏北泗阳县和苏南无锡市的调查发现,在较为普遍的大学生村官创业现象中,存在着“利己”和“公利”两种类型,进而对大学生村官的角色定位产生“利己型创业者”和“公利型创业者”。本文就其中的“利己型创业者”角色类型深入思考,探讨了其行为表现和特征,分析了其形成的原因,使社会对大学生村官这一群体能有更全面的认识。     

水稻谷氨酸脱羧酶基因(OsGAD3)分子进化与表达分析

利用分子克隆技术从8个水稻品种中克隆到谷氨酸脱羧酶基因OsGAD3,并进行了相关的生物信息学及表达谱分析.结果表明,不同水稻品种OsGAD3的核苷酸序列差异性很小,都在1%以内,在氨基酸序列上都具有保守的结构域,在C末端均具有类似于OsGAD1结合CaM的关键氨基酸位点,但不同于OsGAD2.系统进化树分析表明,不同水...