宅基地退出补偿政策是影响宅基地自愿有偿退出进度与成效的重要因素.运用文献梳理法和历史脉络法,系统梳理1949年以来中国实行的农村宅基地退出补偿政策,根据补偿的手段与方式不同,将其划分为3个主要阶段;深入剖析现有宅基地退出补偿政策在补偿原则、补偿范围、补偿内容、补偿标准等方面的特点和不足;未来,可以从出台农村宅基地退出补偿条例、客观评估宅基地的价值、优化增值收益分配方式、健全保障支持政策等方面入手,完善农村宅基地退出补偿政策体系.

澳大利亚是奶业发达国家,具有较高的奶业生产水平和成本优势,乳制品具有国际竞争力.澳大利亚牛奶自给率达到140％以上,全国1/3以上的牛奶加工后出口,是世界第四大乳制品出口国,也是主要的燕麦草出口国.目前中国已成为澳大利亚最大的乳制品出口国和第二大燕麦草出口国.2015年中国和澳大利亚正式签署《中国—澳大利亚自由贸易协定》(以下简称中澳自贸协定),建立中澳自贸区,并对我国从澳大利亚进口的乳制品、草饲料等按照不同类别设置了5、10、12年的过渡期,关税由相应类别的基础税率逐渐降为0.

2008-2017年中国乳制品进口增速过快,进口乳制品虽然在一定程度上满足了国内乳品企业对原料的需求及居民多样性的消费需求,但以原料奶粉为主的乳制品大量进口严重影响了国内奶牛养殖业,压缩了婴幼儿配方乳粉市场空间,液态奶大量进口也影响消费者福利.建议国家相关部门开展进口液态奶品质分析评价,加大饮奶知识科普宣传力度,引导消费者理性消费.

2018年7月6日12:01开始,中国对美国部分进口商品加征关税措施正式实施.此次征税的清单包括了鲜奶、奶粉、炼乳、酸奶、奶油、乳清、奶酪等乳制品,以及大豆、苜蓿等饲草料,加征额度高达25%,但婴幼儿配方乳粉不在加征关税清单之列(表1).加征关税对我国奶业会有何影响?

A novel dual-template molecularly imprinted polymer (DMIP) was prepared with atrazine and prometryn as the template and applied as a class-specific adsorbent for simultaneously selective solid-phase extraction of seventeen triazine herbicides and metabolites from complex matrices. For comparison, a non-imprinted polymer (NIP) and two single-template imprinted polymers (SMIPs) were also synthesized using the same procedure of DMIP, but in the absence of the template (NIP) or with one template (SMIP). Various parameters affecting the extraction performance of DMIP-SPE were investigated in detail. Under the optimum conditions, the enrichment efficiency, class-selectivity and reusability of DMIP-SPE were evaluated. Only DMIP-SPE possessed high affinity and good selective recognition ability for all the seventeen targets including chloro-, thiomethyl- and methoxy- triazines. Further, a DMIP-SPE-LC-MS/MS method was developed for simultaneously determining trace triazine herbicides and metabolites in maize, wheat and cottonseed samples. The method showed good linearity (r>0.9941) in the range of 10-200 μg kg-1, high sensitivity with low limits of detection of 0.5-8.8 μg kg-1, and satisfactory recoveries of 61.3-105.9% with relative standard deviations of 2.1-10.7%. These results highlighted the good application prospect of the multi/dual-template imprinting strategy in the high-throughput analysis of various concerned contaminants in agro-products.

A selective, environmentally friendly, and cost-effective sample extraction method based on a combination of subcritical water extraction (SWE) and molecularly imprinted solid-phase extraction (MISPE) was developed for the determination of eight triazine herbicides in soil samples by liquid chromatography-tandem mass spectrometry (LC-MS/MS). In SWE, the highest extraction yields of triazine herbicides were obtained under 150°C for 15min using 20% ethanol as the organic modifier. Addition of MIP during SWE increased the extraction efficiency, and using MIP as a selective SPE sorbent improved the enrichment capability. Soil samples were treated with the optimized extraction MIP/SWE-MISPE method and analyzed by LC-MS/MS. The novel technique was then applied to soil samples for the determination of triazine herbicides, and better recoveries (78.9%-101%) were obtained compared with using SWE-MISPE (30%-67%). Moreover, this newly developed method displayed good linearity (R2>0.99) and precision (2.7-9.8%), and low enough detection limits (0.4-3.3μgkg-1). This combination of SWE and MIP technology is a simple, effective and promising method to selectively extract class-specific compounds in complex samples.

A novel dummy molecularly imprinted polymer (MIP) for selective extraction and preconcentration of chloramphenicol (CAP) has been successfully developed by precipitation polymerization using thiamphenicol (TAP) as the dummy template, methacrylic (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker, and methanol as the porogen. The performances and recognition mechanism of MIPs and non-molecularly imprinted polymers (NIPs) has evaluated in terms of adsorption isotherms and adsorption kinetics. The results showed that the MIPs exhibited significant specific recognition toward CAP in water with a large adsorption capacity. To test the feasibility of MIP in real samples, the obtained MIPs were applied as the selective sorbents for the solid-phase extraction of CAP from milk samples. Under optimized conditions, a rapid, convenient, and efficient method for the determination of CAP in milk samples based on MISPE coupling with high-performance liquid chromatography tandem mass spectrometry (LC-MS/MS) was throughly established. The method showed excellent recoveries (96.04~108.68%) and precision (RSDs <7.97%, n = 5) for milk samples spiked at three concentration levels (2, 5, and 10 μg L−1). The results demonstrated that the CAP in milk samples could be separated and purified through molecularly imprinted solid-phased extraction (MISPE), and this method could solve the leakage of template by the employment of dummy template effectively.

国内奶业形势 国内生鲜乳产量同比继续下降,2017年9月价格开始反弹 据农业部发布的全国生鲜乳产量指数显示, 2015~2017年,生鲜乳产量总体呈下降趋势.以2015年1月为基期,从2017年4月起,国内生鲜乳产量不断下降(图1),7月生鲜乳产量同比减少3.76%,环比减少2.95%;1~7月累计生鲜乳产量同比减少0.98%.

2016年2月21～26日,对上海、广东两地5家奶牛养殖场、3家乳品加工企业和3家超市进行了调研.结果显示:两地奶牛养殖业比较平稳,没有生鲜乳被拒收的情况;在消费淡季,乳品企业仍保持了较好的发展,且收购的生鲜乳用于喷粉的问题不突出;在消费市场上,调研期间,乳制品促销力度较春节前有所下降,另外,进口乳制品品种不断增长,价格普遍高于国产品牌.调研还发现,奶牛场面临着环保压力大,人员成本上涨严重,生鲜乳收购价格协调机制有待完善等问题.建议借鉴上海的经验推广第三方检测和价格协调机制,修订和完善相关标准,加强监管和宏观调控,扶持适度规模牧场发展,提升生产管理水平,科学引导乳制品消费等.

A fluorescent competitive assay for melamine was first developed utilizing dummy molecularly imprinted polymers (DMIPs) as artificial antibodies. This method is based on the competition between fluorescent substances and the unlabeled analyte for binding sites in synthesized DMIPs and the decreased binding of fluorescent substances to DMIPs due to increased concentrations of melamine in the solutions. DMIPs for melamine were synthesized under a hot water bath in the presence of the initiator azobisisobutyronitrile (AIBN) using 2,4-diamino-6-methyl-1,3,5-triazine (DAMT) as a dummy template, methacrylic acid (MAA) as a functional monomer, and ethylene glycol dimethacrylate (EGDMA) as a crosslinking agent. The adsorption capacity and selectivity of DMIPs for melamine were evaluated by the isothermal adsorption curve and Scatchard analysis. The evaluation results showed that the synthesized DMIPs had specific recognition sites for melamine and the maximum adsorption amount was 1 066.33 μg g−1. Later, 5-(4,6-dichlorotriazinyl) amino fluorescein (DTAF) with a triazine ring, which slightly resembles melamine, was selected as the fluorescent substance. The fluorescent competitive assay using DMIPs as the antibody mimics was finally established by selecting and optimizing the reaction solvents, DMIPs amount, DTAF concentration, and incubation time. The optimal detection system showed a linear response within range of 0.05–40 mg L−1 and the limit of detection (LOD) was 1.23 μg L−1. It was successfully applied to the detection of melamine in spiked milk samples with satisfactory recoveries (71.9 to 86.3%). According to the comparative analysis, the result of optimized fluorescent competitive assay revealed excellent agreement with the HPLC-MS/MS result for melamine.

建立了同时测定蔬菜和水样品中甲醇、甲苯、邻二甲苯、间二甲苯、对二甲苯等5种挥发性农药助剂残留量的顶空/气相色谱-质谱分析方法(HS/GC-MS).对溶剂种类、NaC1溶液浓度、平衡温度、平衡时间以及GC-MS等分离检测条件进行优化.当顶空平衡温度为80℃,平衡时间为20 min,采用DB-624毛细管柱(30 m×0.25 mm×1.4 μm)进行分离,选择离子监测模式(SIM)进行检测,可获得良好的分离效果和定量结果.甲醇和苯系物分别在0.12 ～80 mg/L,0.0003 ～0.20 mg/L的浓度范围内线性关系良好,相关系数均不小于0.9993,检出限分别为0.04 mg/kg和0.0001 mg/kg.5种挥发性农药助剂在不同添加水平下的平均回收率为63.5％ ～115.4％,相对标准偏差为1.2％～9.4％.方法适用于西红柿、黄瓜等蔬菜和水中挥发性有机溶剂类农药助剂的残留检测.

通过两年两地的田间试验,采用分散固相萃取-气相色谱-质谱联用的分析方法,研究了50％啶酰菌胺水分散粒剂在草莓和土壤中的残留及消解动态,并探讨了不同农作物品种、环境气候条件对农药消解速率的可能影响.结果表明:在草莓中添加0.05、0.3和3 mg/kg的啶酰菌胺标准品时,其平均回收率为91％～121％,相对标准偏差(RSD)为5.8％ ～9.9％;在土壤中分别添加0.1、0.3和3 mg/kg的啶酰菌胺时,其平均回收率为91％ ～ 100％,RSD为5.4％～6.5％.草莓和土壤中啶酰菌胺的定量限分别为0.05和0.1 mg/kg.啶酰菌胺在草莓中的消解动态符合准一级动力学方程,半衰期为6.2～11.8 d,但在山东和北京土壤中的消解试验均未拟合出指数方程.试验表明,50％啶酰菌胺水分散粒剂以有效成分337.5 g/hm2的推荐高剂量分别施药3次,采收安全间隔期为3d时,啶酰菌胺在草莓和土壤中的最大残留量分别为1.97及0.38 mg/kg,最终残留量符合残留要求,可以安全使用.

Schematic illustration of a direct competitive immunomagnetic-bead-based enzyme-linked immunosorbent assay (IMB-ELISA) to detect the triazophos pesticides.

本文以2-氯-4,6-二氨-1,3,5-三嗪为虚拟模板分子,甲基丙烯酸为功能单体,乙二醇二甲基丙烯酸酯为交联剂,在纳米硅球表面合成了特异性吸附三聚氰胺的表面分子印迹聚合物(MIPs)。采用红外光谱、电镜等手段对印迹聚合物进行了表征;用静态吸附曲线和Scatchard方程评价了印迹聚合物对三聚氰胺的吸附性能。将合成的表面印迹聚合物作为填料制备分子印迹固相萃取(MIP-SPE)柱,优化了固相萃取条件,与液相色谱串联质谱联用建立了牛奶样品中三聚氰胺的MIP-SPE-HPLC/MS/MS分析方法。实验结果表明,以2-氯-4,6-二氨-1,3,5-三嗪为虚拟模板制备的MIPs能够特异性吸附三聚氰胺,其MIP-SPE柱可以富集净化牛奶样品中的三聚氰胺,添加回收率为80.9%~86.5%,相对标准偏差小于6.4%,定量限(10S/N)为0.023 mg/L。

A gas chromatography-mass spectrometric( GC-MS) method was developed for the simultaneous determination of toluene, o-xylene, m-xylene, p-xylene, N, N-dimethyl formamide( DMF) and dimethyl sulfoxide( DMSO) residues in agro-products. The target compounds were extracted from various vegetables and crops by acetonitrile solution,and further analyzed by GC-MS in selected ion monitoring after chromatographic separation on an Agilent DB-624( 30. 0 m × 250 μm ×1. 4 μm) column. Identification was achieved by the retention time and the ion ratio,and quantification was done by the external standard method. The results showed that the calibration curves were linear in the range of 0. 005-0. 500 mg / L for toluene,p-xylene,o-xylene and m-xylene,0. 025-0. 125 mg / L for DMF,and 0. 050-0. 500 mg / L for DMSO,with correlation coefficients of 0. 992 0-0. 997 1. The spiked recoveries of six organic solvents residues were in the range of 60. 1%-115. 2% with relative standard deviations( RSDs) not more than 11. 0%. The limits of detection were in the range of 0. 002-0. 050 mg / kg for benzene series,0. 010-0. 025 mg / kg for DMF, and0. 060-0. 150 mg / kg for DMSO. The method is simple,rapid,sensitive and accurate,and could be used for the simultaneous determination of volatile organic solvents residual in agricultural products.

We report on a method for the determination of the herbicide atrazine in tap water samples using melamine-modified gold nanoparticles (Mel-AuNPs). If a solution containing atrazine is added to a solution of such NPs, a color change occurs from wine-red to blue. This is due to a transition from monodisperse to aggregated Mel-AuNPs and caused by strong hydrogen bonding between atrazine and melamine. The color change can be monitored by a UV–vis spectrophotometer or with bare eyes. The ratio of the absorbances at 640 and 523 nm is linearly related to the logarithm of the atrazine concentration in the 0.165 to 16.5 μM range, and (with different slope) in the 16.5 μM to 330 μM range. The detection limit of atrazine is as low as 16.5 nM (S/N = 3). The method was successfully applied to the determination of atrazine in spiked tap water and gave recoveries that ranged from 72.5 % to 102.3 %.

A class-specific molecularly imprinted polymer( MIP) with strong selectivity and adsorbability for triazines and their metabolites was synthesized by bulk polymerization using atrazine as template molecule,methacrylate acid( MAA) as functional monomer,and trimethylolpropane trimethacrylate( TRIM) as cross-linker. And a rapid method was developed for the determination of 8 triazines and their metabolites in maize,wheat and cotton samples by molecularly imprinted solid phase extraction and high performance liquid chromatography tandem mass spectrometry( MISPE / HPLC- MS /MS). The proportion of atrazine and methacrylate acid was screened and optimized by ultraviolet spectrometry. The morphology of polymer was observed with scanning electron microscope and transmission electron microscope. The recognition performance of structure analogues on the molecularly imprinted polymer was studied by HPLC- MS / MS. The result indicated that the synthesized molecularly imprinted polymer had a strong affinity and specificity for atrazine and its structure analogues,and the molecularly imprinted solid phase extraction cartridge had a good selectivity and purifying a-bility. The mean recoveries of these compounds in maize,wheat and cotton were in the range of61. 1%- 107. 6%,with relative standard deviations( RSD) below 11 %. The limits of detection( S /N = 3) were in the range of 0. 4- 8. 1 μg /kg. The MISPE- HPLC- MS /MS method could be applied in the routine surveillance of actual samples.

[Objective] The objective of this study is to study the degradation dynamics of abamectin in cucumber and soil, and to formulate a scientific basis for the reasonable dose and the pre-harvest interval on controlling cucumber root-knot nematode with hole application. [Method] Degradation dynamics experiments were conducted by application abamectin once on cucumber and soil with hole application at 5.62 g·m-2 (1.5 times recommended dosage) after transplanting cucumber seedlings. Degradation dynamics samples were collected and determined at random from each plot at different time intervals i.e, 0 day (2 h after application),&nbsp;1, 3, 5, 7, 10, 14, 21, 28, and 45 days after the abamectin application. Two doses were set in terminal residue experiment. Abamectin was applied once at 3.75 g·m-2 (low concentration, recommended dosage) and 5.62 g·m-2 (high concentration, 1.5 times recommended dosage) after transplanting period of cucumber seedlings. Terminal residue samples were collected and determination of abamectin during the harvesting periods. The dispersive solid phase extraction-high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was used to determine the abamectin residue in cucumber and soil. The homogenized cucumber samples, plant samples or soil samples (10 g) were firstly weight into a polypropylene centrifuge tube. After adding 4 g Na2SO4, and 1 g NaCl, the sample was extracted by 10 mL acetonitrile. Secondly, the extraction solution was sonicated and centrifuged for several minutes. Then 2 mL of the clarified supernatant was transferred into a clean centrifuge tube containing 50 mg of C18 and 50 mg PSA dispersive solid phase extraction (DSPE) sorbents for purification. Finally, the solution filtered through a 0.22μm membrane prior to LC-MS/MS analysis. [Result]The established method for determination of abamectin in cucumber and soil with DSPE combined LC-MS/MS was rapidly and easy of operation. The recoveries of abamectin in cucumber and soil were 78%-101%with RSD between 1.9%and 9.4%with spiking at 10μg·kg-1, 50μg·kg-1 and 100μg·kg-1. The limit of quantitation (LOQ) of this method was 10μg·kg-1, which could meet the requirement of max residue limits (MRLs) of abamectin. In degradation dynamics experiments, abamectin was not detected in all degradation plant samples collected from in Beijing and Harbin, which suggested that it is not a systemic pesticide. However, abamectin was detected in all soil samples in degradation experiment. The degradation dynamic equations of abamectin in soil were fitted the first-order reaction dynamic equations, and the half-lives of degradation of abamectin were estimated at 7.9 d and 18.7 d in soil. The residue period of abmectin was longer with hole application compared to that with spray application in soil. Abmectin residue was detected in three soil samples collected from Beijing in 2012 with concentration of 10μg·kg-1, 30μg·kg-1 and 170μg·kg-1, respectively. And similarly, abmectin residues were found only in two soil samples collected from Harbin with concentration of 10μg·kg-1. [Conclusion]The abamectin sustained release granules (1%) applied with hole application at 3.75 g·m-2 can be considered safe in cucumber planting.

A sensitive method was developed for determination of prothioconazole and prothioconazole-desthio in peanut. The analytes were extracted from the peanut samples by acetonitril, and defatted with n-hexane saturated by acetonitrile. Then the samples were purified by dispersion solid phase extraction using ODS C-18 sorbent, and analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS). Prothioconazole and prothioconazole-desthio were separated on a reversed phase column using a gradient elution program of aqueous solution containing 5 mmol/L ammonium acetate and 0.2% acetic acid (A) and acetonitrile solution (B). Analyte confirmation was performed using multiple reaction monitoring (MRM) with one precursor ion and two productions as identifiers. The recoveries were in the range of 87.2%-102.46%, and the relative standard deviation (RSDs) were less than 9.97% at 2.0, 4.0, and 20.0 mu g/kg three spiked levels for prothioconazole and prothioconazole-desthio. The limits of quantification (LOQ) for the two analytes were 2.0 mu g/kg.

A novel method using magnetic molecular imprinting polymers (MMIP) specific for recognizing, separating, and extracting melamine in bovine milk was developed with an external additive magnetic shelf in this paper. The MMIP was synthesized with Fe3O4 nanoparticles and molecular imprinted polymer synthesis technology. With the help of an elution step using methanol/acetic acid mixture elution, the melamine could be collected and concentrated. By using high performance liquid chromatography combined with this pretreatment technique, the analytes eluted from the magnetic polymers can be determined. This extraction method was validated by analysis of incurred bovine milk matrix. The proposed method simplified the procedures of classical solid-phase extraction method and improved the reliability of method. The obtained recoveries of this method were in the range of 85.04–105.2% in spiked milk samples. The limit of detection (LOD) was below 29.2 ng g−1.