对农村税费改革问题的思考

农村税费改革的目的是通过改革减轻农民负担,规范国家、集体与农民的收入分配关系,积极促进农村经济的可持续发展。农村税费改革的基本思路是:继续深化农业税制改革,构建合理的农村收费制度,完善种种配套措施。     

基于农户视角的农户灌溉区域差异及原因分析——以三工河流域为例

基于问卷调查, 运用数量统计和最小二乘估计, 分析新疆三工河流域不同区域农户灌溉差异, 并探讨差异性的原因。研究结果显示: (1)三工河流域从上游到下游节水滴灌面积比例和水价依次递增, 上、中、下游滴灌比例分别为3%、10%、28%, 水价为<0.075元·m^-3、0.069~0.075元·m^-3、0.13~0.35元·m^-3; 灌水量和农户水费负担依次减少, 灌水量为18 510 m³·hm^-2、12 810 m³·hm^-2、9 075 m³·hm^-2, 水费负担为18%、14%、12%; 种植结构由传统作物主导向经济作物主导发展, 种植结构趋于合理。(2)自然因素是导致农户灌溉差异的根源, 不同区域水资源多寡、土壤保水性、地块大小与破碎度的差异, 导致农户节水意识、节水设施选择意愿及政府调控措施的不同。(3)政府一方面通过调整水价增加农户灌溉压力, 减少农户用水量; 一方面通过提高渠系质量和激励农户采用节水设施提高水资源利用效益, 提升作物的灌水需求曲线。实证结果显示: 水价每上涨0.01元·m^-3, 灌水量就会减少484 m³·hm^-2; 采用滴灌技术, 灌水量减少1 617 m³·hm^-2; 改善渠系质量使土渠向水泥渠、板板渠发展, 灌水量减少736 m³·hm^-2。     

我国长三角地区淡水池塘养殖水产品中抗生素残留及对人体暴露的贡献评价

为探究我国长三角地区淡水养殖水产品中抗生素残留特征及食用风险,于2019年7—10月采集上海、浙江、江苏、安徽、福建等5个地区淡水养殖池塘3类水产品(鱼类、虾类、蟹类),使用高效液相色谱-串联质谱法(LC-MS/MS)检测水产品中的9种常见抗生素,并根据人体可接受的每日摄入量(ADI)及养殖水产品消费对抗生素暴露的贡献率(CR)分别评价食用安全性和暴露风险。结果表明:9种抗生素均有检出,检出频率范围为38.1%~90.5%,浓度范围为nd~25.25 ng·g^-1;估算的每日摄入量(EDI)远低于ADI;Σ抗生素的贡献率范围为<0.01%~29.77%。研究表明,水产品摄入不会对人体健康构成抗生素暴露风险,但食用水产品时,喹诺酮类和大环内酯类抗生素的摄入应引起关注。     

农村公共产品供给与减轻农民负担

农民负担实际上是与农民有关的公共产品成本的分摊,而这种分摊存在着体制缺陷,这种缺陷导致了农民的生产效益低下,农民负担逐步加重。要改变这种现状就必须对农村公共产品供给体制进行改革和完善,以期从根本上减轻农民负担。     

Characterization of adaptive immune responses induced by a new genetically inactivated Salmonella Enteritidis vaccine

The superior conservation of antigenic determinants on the surface of genetically inactivated bacterial ghosts makes them attractive immunogenic inactivated vaccine candidates. The efficacy of Salmonella Enteritidis (SE) ghost vaccination was evaluated in chickens by characterizing the nature of the adaptive immune response. Chickens from the immunized group demonstrated significant increases in SE-specific plasma IgG, intestinal secretory IgA, and lymphocyte proliferative response. The populations of CD4, CD8, and TCR γδ T-cells in immunized chickens were significantly greater than in the controls. Increased levels of IFN-γ, IL-2, IL-6 and IL-10 were observed in peripheral blood mononuclear cells stimulated with SE specific antigen. After virulent SE challenge, the immune system of immunized chickens was rapidly stimulated, as indicated by significantly increased population of CD4 and CD8 T-cells. Furthermore, the immunized group exhibited decreased challenge strain recovery of the internal organs compared to the non-immunized group. Together, these data indicate that the immunization induced humoral and cell-mediated immunity might be responsible for significant reduction of the virulent challenge strain load in the internal organs of immunized chickens.     

Parasitic load and histological aspects in different regions of the spleen of dogs with visceral leishmaniasis

Leishmania infantum causes from subclinical infection to severe disease in humans and dogs. The spleen is one of the organs most affected by the infection. Although evidence exists that the parasitic load distribution and histological alterations may not be homogeneous in the affected organs of naturally infected individuals, it has not been formally demonstrated using the current techniques used for studying the disease.In six dogs naturally infected with Leishmania, parasitic load and histological changes were compared in samples collected from the lower, middle and upper third of the spleen.Parasitic load in the spleen of the group of dogs was variable, revealing a difference of 61 times between animals with the lowest and the highest parasitism. The set of parasitic load values of each dog showed a cluster trend, when compared to the other animals. Nevertheless, the parasitic load values of each dog showed a variation ranging from 3.2 to 34.7 times between lowest and highest value. Histological changes showed recognizable variation in frequency (granulomas) or intensity (perisplenitis) in the spleen of 2 out of the 6 dogs. The agreement of histological findings between samples collected from the different thirds of the spleen was good (kappa coeficient, 0.61–0.80) very good (0.81–0.99) or perfect (1.00), for most of the parameters analyzed.Variability of parasitic load and, to a lesser extent, histological changes in spleen of dogs with visceral leishmaniasis is observed. Such variability may be taken in account in the design of studies on pathogenesis, vaccine and therapeutic drug development.     

基于生态容量的中国资源环境基尼系数研究

选取中国内地2007年SO2排放、工业固废产生、废水排放和能源消耗作为评价指标,以＂森林面积＂和＂农业用地＂为＂生态容量＂表征指标,计算基于生态容量的中国资源环境基尼系数,以绿色负担系数判断资源消耗和污染物排放不公平因子.结果表明：4项指标资源环境基尼系数分别为0.56、0.57、0.67、0.60,表现出极大区域分配不公平性.由绿色负担系数可知,上海、天津、江苏、北京、山东、河北、山西、河南、辽宁、浙江、重庆、广东等经济发达省市是主要不公平因子,需要转变经济发展模式,减少环境压力.