2017 年,浙江省绍兴市柯桥区启动"闲置农房激活计划".2020 年,绍兴市入选新一轮农村宅基地制度改革整市推进试点,为柯桥区全方位盘活闲置宅基地和闲置农房提供更明确的政策导向和更有力的制度支撑.从"摸着石头过河"到"架桥过河",柯桥区紧扣"全域联动激活"理念,深化宅基地"三权分置"探索,着力构建闲置农房开发利用长效机制.

Farm size and scale efficiency are hot issues.In recent years,farm size has expanded rapidly in China.Due to the lack of scale management experience,farmers have not realized yield or income growth and farmers' enthusiasm for production has declined.It is therefore necessary to study the scale efficiency of grain production.Here,we discuss farmer's scale efficiency using maize farming households as an example.The data was collected from three maize producing provinces,Heilongjiang,Henan and Sichuan,located in Northeast,North and Southwest China.Based on 517 surveys we employed the DEA approach to estimate maize scale efficiency and utilized a Tobit regression to analyze influencing factors.The results indicated that overall scale efficiency is 0.90.It is high but there is room for efficiency improvements.The scale efficiency of maize production is significantly different in the provinces.The highest scale efficiency is in Heilongjiang and the lowest is in Sichuan.By dividing the data according to farmer scale we found that scale efficiency drops with increasing scale after rising first.Based on these findings we should promote scale management suiting local conditions instead of expanding blindly.Tobit regression shows that the higher the education level of household head,household head as a migrant worker in cities have a significant positive impact on the scale efficiency.The proportion of non-farming income to net income of household is negatively correlated with scale efficiency.Therefore we should strengthen the training of farmers,cultivate new professional farmers and provide better technical support for scale farmers.

With the rapid development of China′s arable land circulation,some new business entities such as family farms, farmers′ cooperatives, professional households, and agricultural enterprises have appeared.However, the households are still the main body of land management.The purpose of this paper is to analyze the basic characteristics of grain farmers′ land circulation for improving thearable land circulation policy.The descriptive statistical method was used based on survey data of farmers and villages in Henan, Heilongjiang, Zhejiang and Sichuan provinces.The results showed that farmers land transfer rate increased year by year, the farmers with an avea of less than 1.33hm2 decreased significantly.Because of the economic development of Zhejiang province, the proportion of land circulation was leading in 2011 compared with the other three provinces.The trend of farmland centralization in other 3 provinceswas obvious.The trust relationship between acquaintances can reduce the transaction cost of land transfer.However, due to the lack of stable cultivated land transfer contract, it was difficult to assess the market value of cultivated land.Agricultural subsidies had become a part of the farmers′income.The trend of centralization of cultivated land was very obvious and different in provinces.The circulation of arable land basically follows the law, voluntary and paid principle.The transfer of land between farmers was mainly spontaneous.Finally, it proposed some countermeasures, such as establishing land transaction platform to provide effective services, playing the government′s role in the guidance, norms, coordination and service, supporting the large-scale farmers, accelerating the reform of household registration system, optimizing the external environment of the arable land circulation, and promoting the arable land circulation and large-scale management.

To raise the spectral resolution of fiber-optic Fourier transform spectrometer,a PZT driving power of Fiber-optic phase modulation,composed of a low-frequency signal generator and a high voltage amplifier,was designed.The bode plot and open loop phase shift plot was used to analyze and discuss the stability of circuit thoroughly,when the capacitive loads with higher capacitance were driven.The result of experiment indicated that high spectral resolution of fiber-optic Fourier transform spectrometer could be achieved with the driving power.

Heavy metal pollutions in the soil of farmland are regarded as serious threats to rural environment in China.Human activities,such as intensive livestock,sewage irrigation,large amounts of agrochemicals input and the rapid urbanization are proved to be the main sources of the heavy metals.Yucheng City is located in Huang-Huai-Hai plain,the largest alluvial plain and important agricultural area in China.The concentrations of Cr,Ni,Pb,As,Hg,Cd,Cu and Zn in the topsoi(l0~20 cm)of the farmland in Yucheng City were analyzed,and their relations with different human activities were discussed.The potential ecological risks of these heavy metals were assessed.Furthermore,the heavy metal concentrations in wheat grown in the sampled soils were also collected and analyzed to compare those in soils.The results showed that the concentrations of the eight heavy metals in all of the soil samples were far lower than those critical values of the National Soil Quality Standard(Grade II)except Cd,while they were all higher than that of the backgrounds in the soils of the alluvial plain of the lower Yellow River.The rapid urbanization,sewage irrigation and long-time typical manure usage were responsible for the high value of heavy metals in soils.The potential ecological risks of Cr、Ni、Pb、As、Cu、Zn were at a lower level while that of Hg and Cd were at a higher level.The higher e-cological risk of soil Cd was mainly derived from the rapid urbanization,intensive livestock and sewage irrigation.And that of soil Hg was lo-cated in the suburb of Yucheng City and the area irrigated with sewage from Tuhai River.The potential ecological hazard index of the eight heavy metals in soils followed the sequence as suburban farmlandfarmland irrigated with sewagefarmland with typical manure usedfarm-land irrigated with groundwaterfarmland irrigated with the Yellow River.Hg and Cd concentrations in some wheat samples were as high as or even higher than that of critical values of the National Standard(GB2715—2005).

According to chemical conditions, peatlands usually defines three types: ① minerotrophic (true fens), ② ombrotrophic (raised bogs), and ③ transition (poor fens). All peatlands, including bogs, develop in waterlogged conditions where dead plants decay slowly because of a lack of oxygen. The result of this in-situ accumulation of organic matter is peat. The rate of decay is so slow that the dead plant remains can resemble the living material even after several thousand years. One type of environmental archive is the peat bog. Peat bogs contain an unparalleled record of our past. A rich archive of information lies preserved in bogs. Much of this is organic, and has a capacity to expand our understanding of people, culture, economy and climate far back into prehistory. The research aim of peat bog archives is the reconstruction of the climate and the climate changes and the changes of the dust and pollutant concentrations in the environment from Holocene to the last hundred years. An ombrotrophic bog is nourished entirely by precipitation,that is, that the plants growing at the surface are supplied with nutrient elements exclusively by atmospheric sources such as dust, rain, and snow,rather than by groundwater. It is therefore excluded from all non-atmospheric inputs of particulate matter. Moreover, since water movement at or near the bog surface is slow and limited, any deposited matter remains largely. A history of particulate atmospheric pollution is therefore preserved as the peat accumulates. Ombrotrophic peat bogs are very suitable environmental archives because all the nutrient and pollutant entries stem from dry and wet deposition from the atmosphere only. Peat bogs provide widespread terrestrial archives of Holocene environmental change and atmospheric metal deposition. During the last 20 years, peat cores from ombrotrophic peat bogs have proved to be meaningful archives of atmospheric deposition of trace elements. Lead especially has been extensively studied and its immobility in the peat column is well demonstrated. Other elements have also been preserved in the peat column. It is concluded that particular strengths of the archive are the current diversity of peat-based palaeo-environmental research and the potential for multiproxy analyses to be applied to a range of research issues. Dating recent peat deposits has emerged as an important task for estimating rates of organic matter accumulation and atmospheric pollutant deposition in peat bogs. The dating approaches include both continuous dating methods and chrono-stratigraphic markers that can be measured in peat and correlated temporally with known historical events. And multiple dating techniques were recommended to employ. The slightly insufficient parts of the overseas research on peat bogs archives are more focused on records, but paid less attention on mechanism research. Recently, scientists from many disciplines have gradually recognized the importance of peat bogs to the global environment.

This article discussed the distribution of major and trace elements of peat in Yuanchi,Changbai Mountain.Four profiles were collected with Wardenaar peat sampler produced in Netherlands.Each sample was cut into 1～2 cm at the present.As far as the special physical conditions in Yuanchi are concerned,the content of major and trace elements(Na、K、Mg、Ca、 Al、Ti、Fe、Mn、Zn、Pb、Cu)were determined among different peat bogs.The elements distribution with depth in each peat profile was fully analyzed.Also we have analyzed the enrichment of different elements in peat profiles.Through the calculated M/Ti(M refers to Na、K、Mg、Ca、 Al、Ti、Fe、Mn、Zn、Pb、Cu) ratio,compared with ratio of M/Ti collected from literature,we concluded the differences among different peat bogs.The increasing content of Mn、Zn and Pb from bottom to top in peat profiles proves the increasing pollution of them in present environment,which has profound implications for environment.

在简要介绍了可编程逻辑器件及其发展进程的基础上,重点介绍了Altera公司的MAX 7000S可编程逻辑器件的结构、特点及逻辑实现方法.最后给出了它在线阵CCD数据采集卡中的具体应用实例.

0 引言 很多场合需要对气体的流量进行精确地测量.随着电子技术的发展,人们希望测量器件能直接给出电信号以便用微机进行数据采集与处理.但流量的测量装置在多数情况下难以给出电信号,然而压差传感器技术却已很成熟从而方便地提供模拟电信号.