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91.
兰州市居住空间分布及其成因   总被引:1,自引:0,他引:1  
城市居住空间是城市空间的重要组成部分。兰州市是典型的河谷型城市,对其居住空间进行研究,有助于揭示该类城市居住空间分布规律,合理引导城市居住空间的发展,优化城市居住空间结构。基于统计资料并结合实地调查,运用Arcgis软件的空间分析功能,从定量分析角度揭示出兰州市居住空间呈现沿交通线集聚分布、区域布局不均衡以及居住空间分异现象初显的特点。并从自然地理环境、城市规划、住房制度、房地产业的发展以及交通建设方面分析了兰州市居住空间分布形成的原因。  相似文献   
92.
村镇绿化是国土绿化的重要组成,不仅是村镇外在形象的体现,也反映出村镇的文化内涵和地方特色.通过对苏北经济发展现状和各方面条件的研究,提出了适合于苏北村庄绿地建设和管理的规划思想,并在依托案例中提出了村庄绿地规划思路,提出了具有乡土特色的绿地类型以及植物种类和绿化模式,有利于当地生态环境的保护和全面推进苏北地区社会主义新农村建设.  相似文献   
93.
通过样地调查,分析了不同结构草类-落叶松林和杜香-落叶松林林木分布格局特征。研究表明:(1)年龄36 - 65年草类-落叶松林和年龄54 - 63年杜香-落叶松林分布格局中,均匀分布、随机分布和聚集分布所占比例分别为6.2%、50%、43.8%;(2)按林型分,草类-落叶松林分布格局中,均匀分布和随机分布所占比例均11.1%,聚集分布占77.8%。杜香-落叶松林分布格局均为随机分布;(3)树种组成在6落4阔 - 10落范围内,草类-落叶松林和杜香-落叶松林分布格局主要为聚集分布和随机分布两种类型。聚集分布主要集中在树种组成7落3阔 - 9落1阔范围内。  相似文献   
94.
Plant processes, such as leaf expansion, stomatal conductance and transpiration, are affected by soil water, particularly in water-stressed environments. Quantifying the effects of soil water on plant processes, especially leaf expansion and transpiration, could be useful for crop modeling. In order to quantify the leaf expansion and transpiration in response to soil water deficit in three millet species, common (Panicum miliaceum L.), pearl (Pennisetum glaucum L.) and foxtail (Setaria italica L.) millets, a pot experiment was performed at the Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran. The soil water status was characterized by the fraction of transpirable soil water (FTSW). Leaf area and transpiration were measured daily. Relative leaf area expansion (RL) and relative transpiration (RT) data were plotted against FTSW. Finally the FTSW thresholds for RL and RT were calculated using linear-plateau and logistic models. The results showed that the thresholds for RL and RT were 0.68 and 0.62, respectively, based on all measured data of the three millet species using the linear-plateau model, indicating that RL and RT were constant when FTSW decreased from 1 to the threshold point. Thereafter, until FTSW = 0, RL and RT declined linearly with a slope of 1.48 and 1.43, respectively. Although millet is cultivated as a resistant crop in arid, semiarid and marginal lands, it showed an early response to soil water deficit at high FTSW thresholds. As leaf expansion and transpiration can be considered morphological and physiological variables, respectively, the results in this study indicate that millet has strong morphological flexibility when faced with soil water deficit.  相似文献   
95.

声学屏障是一种阻拦鱼类进入危险区域进而保护鱼类资源的重要手段,为筛选鱼类敏感的负趋音作为声学屏障,本研究采用6种单频音 (500~3 000 Hz)和1种宽频音 (扬子鳄吼叫声)作为实验用音对草鱼幼鱼进行负趋音的筛选研究,通过在水槽两端交替播音来对比草鱼幼鱼对不同声音的行为反应。结果显示,大多数实验鱼对声音有反应,扬子鳄吼叫声与其他声音组的差异显著。单频音实验组中播放500 Hz单频音时平均反应次数最大,为 (1.7±0.6)次,而播放扬子鳄吼叫声时平均反应次数高达 (5.0±0.9)次,显著高于其他实验音。在总平均速度中,宽频音组中草鱼的总平均速度显著高于其他组,表明草鱼对扬子鳄吼叫声敏感,产生逃窜行为。研究表明,草鱼对扬子鳄吼叫声具有负趋音性,扬子鳄吼叫声是一种对草鱼具有驱赶、威慑作用的声音。本研究可为过鱼设施中辅助诱驱鱼手段及水利结构中避免鱼类的夹带提供参考依据。

  相似文献   
96.
植物生长素在大果沙棘嫩枝扦插中的应用研究   总被引:2,自引:0,他引:2  
在温室内对5个大果沙棘品种嫩枝用4种植物生长激素处理进行扦插育苗试验,结果表明,吲哚丁酸和生根粉处理效果显著,浑金和向阳两品种更容易扦插成活。  相似文献   
97.
98.
Prostatomegaly is a common finding in older non‐neutered dogs. This study compared the serum testosterone, sperm quality and characteristics of the prostatic fraction between healthy dogs and dogs with prostatomegaly. Blood samples of ten dogs (five dogs from each group) were taken for serum testosterone measurement. Sperm motility, vigour, concentration, viability, membrane functionality and morphology were analysed in sperm‐rich fraction. Osmolality, pH, cell types, and albumin, haemoglobin, acid phosphatase, alkaline phosphatase, glucose, triglycerides, cholesterol, calcium, phosphorus, magnesium and chloride were analysed in prostatic fraction. Dogs with prostatomegaly have the lowest sperm motility, vigour, concentration and functional membrane. Dogs with prostatomegaly have the highest glucose, triglycerides and cholesterol. Glucose was the only constituent positively correlated with serum testosterone and prostate volume. It can be concluded that dogs with prostatomegaly have poorer sperm quality, and glucose, triglycerides and cholesterol in prostatic fraction can be used as prostatomegaly biomarkers.  相似文献   
99.
In the study, the relationship of follicular growth waves, oestradiol and pregnancy rates were investigated during oestrus cycle in cows. A total of 22, Brown Swiss cows (3-5 years old) were used for the study. The ovaries of animals were examined from sixth day of cycle to next oestrus by ultrasound. The follicles that were present in the ovarium were recorded. Follicular growth was observed every day by means of ultrasound examination. The blood samples were taken for analysis of oestradiol simultaneously with ultrasound examinations. The oestrus animals were inseminated. Each animal that inseminated was examined by ultrasound on day 28 after insemination for pregnancy diagnosis. Two follicular growth waves were observed in nine of 22 (40.9%), three waves in 13 of 22 (59.1%) animals. The oestradiol was found in the same concentration but in different release patterns between two and three waves animals. Pregnancy rate in cows with three and two follicular waves did not differ. In conclusion, emergence of three waves of follicular growth was higher in Brown Swiss cows, the analysis of oestradiol could be used for determination of the wave numbers and the animals with different waves may have had the same pregnancy rates.  相似文献   
100.
The purpose of this study was to assess the unilateral prefemoral coelioscopic-assisted approach for ovariosalpingectomy in a d`Orbigny slider (Trachemys dorbigni) using a digital otoscope. Twenty healthy turtles were randomly assigned to one of two groups, for right (GR; n=10) or left (GL; n=10) prefemoral access, for coelioscopic-assisted ovariosalpingectomy. Anesthesia and surgery times, body weight, and ovary/oviduct weight data were recorded. Anesthesia and surgery times did not differ significantly between the groups. Wound closure was the most time-consuming surgical step. Ovary and body weights significantly affected the exposure time of the ipsilateral and contralateral ovaries, respectively. Two intraoperative complications were reported. All the animals recovered uneventfully. The digital otoscope can be safely and effectively used for coelioscopic-assisted single-access, unilateral prefemoral ovariosalpingectomy in d`Orbigny slider.  相似文献   
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