中国土地市场对城乡融合发展的影响

城乡融合发展是实现乡村振兴与推进新型城镇化建设的关键举措,土地市场则是实现城乡要素流通的重要渠道,也是连接城乡发展的关键纽带。本文阐释了城乡融合发展的科学内涵与本质特征,探究了土地市场对城乡融合发展的作用机理,在此基础上,量化分析了中国273个地级及以上行政单元土地市场与城乡融合发展的演进规律,并运用面板数据模型对土地市场与城乡融合关系进行了实证检验,以期从土地市场视角为城乡融合发展提供一条可实现路径。结论如下：（1）城乡融合发展是城乡价值重塑的过程,旨在消除阻碍城乡发展的因素,推动城乡要素自由流动与平等交换,实现城乡发展要素回报趋同,本质是通过城乡互动互补实现城乡地域功能的整体优化。（2）土地市场对城乡融合的作用是利弊双轨的权衡,作用方向取决于土地市场是否是良性市场。城乡二元分配体制与社会融入受阻背景下,扭曲土地市场掣肘城乡融合发展。（3）2005-2013年中国土地市场稳步发展,城乡融合发展水平略低,土地市场规模、土地市场价格与土地市场化程度分别提升113.66%、274.09%与37.07%,59.34%城市的城乡融合发展水平下滑,二者反差明显,且均具时空分异特征。（4）现阶段,土地市场对城乡融合发展更多体现为滞碍作用,但土地市场对城乡融合存在“低水平陷阱”,突破88.64%的抑制拐点,即可发挥土地市场对城乡融合的促进作用。重塑土地市场发展价值取向,加快推进土地市场化改革,探索人口—土地挂钩机制是后续工作的重要方向。     

人类活动净氮输入时空变化特征及其影响因素——以香溪河流域为例

为了阐明人类活动对三峡库区第一大支流香溪河流域氮输入的影响程度,基于人类活动净氮输入（NANI）模型估算了2001~2015年间香溪河流域乡镇水平的人类活动净氮输入,分析了氮输入的主要来源及其动态变化.结果表明：时间尺度上,香溪河流域人类活动净氮输入（NANI）因氮素施用的变化而呈现先上升后下降最后上升的趋势,但2015年相对2001年的NANI下降了143kg N/（km²·a）;空间尺度上,香溪河流域NANI整体呈现北低南高的分布格局,其中NANI输入强度差异较大的区域主要有昭君镇、峡口镇和黄粮镇.从人类活动净氮输入的组成上来看,氮肥施用仍然是最主要的来源（40.06%）,其次为大气氮沉降（29.98%）和食品/饲料净氮输入（27.75%）,作物固氮仅占净氮输入总量的2.21%.香溪河流域的NANI与人口密度和耕地面积比例极显著相关（P<0.001）;而NANI与河流氮输出的相关性不显著,香溪河流域河流氮输出占NANI的比例仅为24.28%.因此,可以通过减少氮素施用降低流域尺度氮素净输入量,但该流域NANI与河流氮输出无直接的响应关系.     

基于不同排放清单的长三角人为CO2排放模拟

目前基于排放清单估算的区域和城市尺度上的人为CO₂排放不确定性较大.为了我国实现碳达峰和碳中和的目标,亟需对我国的区域尺度,特别是大城市群的人为CO₂排放进行准确估算.分别利用两种先验人为CO₂排放数据(EDGAR v6.0清单和EDGAR v6.0联合GCG v1.0的改进清单)作为输入数据,采用WRF-STILT大气传输模型模拟长三角地区2017年12月至2018年2月大气CO₂摩尔分数,再以安徽全椒高塔观测的大气CO₂摩尔分数作为参考值,通过贝叶斯反演方法得到的比例因子改进了模拟结果,并实现了长三角人为CO₂排放通量的估算.结果表明：(1)在冬季,相对于基于EDGAR v6.0模拟的大气CO₂摩尔分数值而言,基于改进清单模拟的大气CO₂摩尔分数与观测值更为一致;(2)模拟的大气CO₂摩尔分数在夜间高于观测值,白天则相反,主要因为排放清单的CO₂排放数据不能表征人为...     

京津唐地区农村-城市转型研究

以农村发展为视角，城乡一体化为背景。详细分析了京津唐地区农村—城市转型的特征、动力机制和类型。通过分析，文章认为促进京津唐地区农村一城市转型的因素一部分来自于农村内部的改革和发展．一部分来自于中心城市的经济技术辐射。在此基础上．作者提出了推进京津唐地区农村-城市转型的主要对策。     

Effects of the Anthropogenic Factor on Bats (Chiroptera: Vespertilionidae) in the Volga Region

Using the example of bats inhabiting the Volga region, the cases in which the anthropogenic factor creates favorable conditions for these animals or significantly reduces their diversity of their fauna are considered. In this context, an opinion concerning the approaches to the conservation of bats is formulated.     

Natural and anthropogenic metal inputs to soils in urban Uppsala, Sweden

Urban soils are complex systems due to human activities that disturb the natural development of the soil horizons and add hazardous elements. Remediation projects are common in urban areas and guideline values are set to represent a desired level of elements. However, the natural content of trace elements may not always equal the desired levels. In this study, an attempt is made to distinguish between metals that are present in the soil due to natural origins and to anthropogenic origins. Seventy-five soil samples of the 0–5, 5–10 and 10–20 cm layers were collected from 25 sites in urban areas of Uppsala City and analysed for aluminium (Al), arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), tungsten (W) and zinc (Zn) using aqua regia for digestion. In order to highlight elements of geological origin, the results were compared to a similar study carried out in Gothenburg City, which has about three times as many inhabitants as Uppsala and has a more industrial history. A cluster analysis was also performed to distinguish between elements of natural and anthropogenic origin. Contents of As, Al, Fe, Cr, Ni, Mn and W in Uppsala were concluded to be of mainly geological origin, while contents of Cd, Cu, Zn, Pb and Hg seemed to have been impacted upon by mainly urban activities.     

基于改进灰色模型的管壁蜡沉积厚度预测研究

为对含蜡原油管道中的蜡沉积厚度进行准确预测,在函数cot(x2)变换的基础上,结合平移变换思想,利用cot(x2+c)变换建立新的改进GM(1,1)模型。以现场管道结蜡数据和室内环道结蜡数据为例,对比改进GM(1,1)模型、基于函数cot(x2)变换建立的GM(1,1)模型及传统GM(1,1)模型之间的预测精度,并分析平移量c对改进GM(1,1)模型预测精度的影响。结果表明:改进GM(1,1)模型的预测精度最高,其次是基于函数cot(x2)变换建立的GM(1,1)模型,而传统GM(1,1)模型的预测精度最低;随着平移量的增大,改进GM(1,1)模型的平均相对预测误差呈现出先减小后增大的趋势,因此合理的平移量有助于模型精度的提高。应用改进GM(1,1)模型来预测管道蜡沉积厚度是可行的,该方法可为含蜡原油管道蜡沉积厚度的准确预测提供参考和借鉴。     

石油加工过程硫转移分布及风险分析

以典型高硫原油加工炼厂为研究对象,选取常减压蒸馏装置、加氢处理装置、延迟焦化、催化裂化等硫化物处理量较大的装置进行硫转移分析,研究石油加工过程中硫迁移分布规律;以硫迁移分布规律为基础,结合各装置中硫的类型分布,分析各装置存在的主要风险,并提出控制建议,为各装置的风险管理提供依据。     

Deriving heart rate variability indices from cardiac monitoring—An indicator of driver sleepiness

Objective: Driver fatigue is considered to be a major contributor to road traffic crashes. Cardiac monitoring and heart rate variability (HRV) analysis is a candidate method for early and accurate detection of driver sleepiness. This study has 2 objectives: to evaluate the (1) suitability of different preprocessing strategies for detecting and removing outlier heartbeats and spectral transformation of HRV signals and their impact of driver sleepiness assessment and (2) relation between common HRV indices and subjective sleepiness reported by a large number of drivers in real driving situations, for the first time.

Methods: The study analyzed >3,500 5-min driving epochs from 76 drivers on a public motorway in Sweden. The electrocardiograph (ECG) data were recorded in 3 studies designed to evaluate the physiological differences between awake and sleepy drivers. The drivers reported their perceived level of sleepiness according to the Karolinska Sleepiness Scale (KSS) every 5?min. Two standard methods were used for identifying outlier heartbeats: (1) percentage change (PC), where outliers were defined as interbeat intervals deviating >30% from the mean of the four previous intervals and (2) standard deviation (SD), where outliers were defined as interbeat interval deviating >4 SD from the mean interval duration in the current epoch. Three standard methods were used for spectral transformation, which is needed for deriving HRV indices in the frequency domain: (1) Fourier transform; (2) autoregressive model; and (3) Lomb-Scargle periodogram. Different preprocessing strategies were compared regarding their impact on derivation of common HRV indices and their relation to KSS data distribution, using box plots and statistical tests such as analysis of variance (ANOVA) and Student’s t test.

Results: The ability of HRV indices to discriminate between alert and sleepy drivers does not differ significantly depending on which outlier detection and spectral transformation methods are used. As expected, with increasing sleepiness, the heart rate decreased, whereas heart rate variability overall increased. Furthermore, HRV parameters representing the parasympathetic branch of the autonomous nervous system increased. An unexpected finding was that parameters representing the sympathetic branch of the autonomous nervous system also increased with increasing KSS level. We hypothesize that this increment was due to stress induced by trying to avoid an incident, because the drivers were in real driving situations.

Conclusions: The association of HRV indices to KSS did not depend on the preprocessing strategy. No preprocessing method showed superiority for HRV association to driver sleepiness. This was also true for combinations of methods for frequency domain HRV indices. The results prove clear relationships between HRV indices and perceived sleepiness. Thus, HRV analysis shows promise for driver sleepiness detection.     

滤纸对青蒿丛生芽诱导及遗传转化的影响

研究了滤纸对青蒿丛生芽诱导及遗传转化的影响.结果表明,培养基上加铺一层滤纸能够明显促进青蒿丛生芽的诱导,丛生芽诱导率可达到97%.在高效丛生芽诱导体系的基础上,探讨了滤纸在根癌农杆菌介导的青蒿遗传转化中的应用.优化后的青蒿转化体系,抗性丛生芽诱导率可达到59.7%,其中,12.5%的抗性丛生芽能发育成抗性生根植株,生根植株PCR检测均为阳性.在部分PCR检测阳性植株中检测到了GUS的稳定表达.该优化的转化体系对青蒿素生物合成分子调控的研究具有重要意义.图5表1参26