温度对WSSV感染中国对虾越冬亲虾的影响

在不同温度下,对中国对虾(Fenneropenaeus chinensis)越冬亲虾进行人工感染白斑综合症病毒(WSSV)实验,利用腹部采血和剪取游泳足进行活体取样.统计感染对虾发病及死亡情况,利用巢式PCR技术检测WSSV,统计实对虾受WSSV感染情况.结果显示,在对虾累计死亡率上游泳足取样的高温组(18～21 ℃)和低温组(9～12 ℃)有显著差异(P=0.041<0.05),高温组明显高于低温组;在对虾受WSSV感染程度上,高温组主要呈严重感染(91.67%),中温组(13～16 ℃)和低温组则主要呈轻度感染,且温度越低受感染程度越轻;在跟踪WSSV感染对虾进程研究上,高温组在48 h检测出WSSV,中温组和低温组则分别在72 h和96 h检测出WSSV,明显滞后于高温组.表明温度对WSSV感染对虾有一定的影响,低温(9～12 ℃)条件下WSSV也能感染对虾且导致死亡,但低温可抑制WSSV的增殖,减缓感染进程,延迟白斑综合症(WSS)的发生.     

Landscape Dynamics and Driving Factors in Da＇an County of Jilin Province in Northeast China During 1956-2000

The landscape pattern of Da＇an County, Northeast China has undergone significant changes since the 1950s as a result of climatic change and human activities. The aim of this paper is to quantitatively study landscape pattern and its spatial dynamics of Da＇an County at the landscape level over the nearly 50-year span. Patch dynamics were examined according to land use and land cover change processes built from a series of images, as well as topographic maps, and temporal patterns built from landscape pattern metrics. The transition matrix of landscape patch types and changes of various landscape metrics were applied. The results showed that, from 1956 to 2000, the landscape within the study area had undertaken a complicated evolution in landscape structure and composition. The outstanding characteristic is that saline-alkali land increased and grassland decreased. As some smaller patches amalgamated, the heterogeneity of patch decreased. All those changes were the synthetic result of both climatic and anthropogenic influences, but the predominant factor was different in different parts. In the southern part of the study area, the landscape pattern changes resulted from the modification of climate obviously, while in the northern part, the landscape pattern changes were mainly caused by human activities, such as the conversion between farmland and saline-alkali land. This phenomenon showed that human activities played more important role in the north than in the south of Da＇an County.     

Sensitivity of penman-monteith reference crop evapotranspiration in Tao’er River Basin of northeastern China

A non-dimensional relative sensitivity coefficient was employed to predict the responses of reference crop evapotranspiration （ET0） to perturbation of four climate variables in Tao＇er River Basin of the northeastern China. Mean monthly ET0 and yearly ET0 from 1961 to 2005 were estimated with the FAO-56 Penman-Monteith Equation. A 45-year historical dataset of average monthly maximum/minimum air temperature, mean air temperature, wind speed, sunshine hours and relative humidity from 15 meteorological stations was used in the analysis. Results show that： 1） Sensitivity coefficients of wind speed, air temperature and sunshine hours were positive except for those of air temperature of Arxan Meteorological Station, while those of relative humidity were all negative. Relative humidity was the most sensitive variable in general for the Tao＇er River Basin, followed by sunshine hours, wind speed and air temperature. 2） Similar to climate variable, monthly sensitivity coefficients exhibit large annual fluctuations. 3） Sensitivity coefficients for four climate variables all showed significant trends in seasonal/yearly series. Also, sensitivity coefficients of air temperature, sunshine hours and wind speed all showed significant trends in spring. 4） Among all sensitivity coefficients, the average yearly sensitivity coefficient of relative humidity was highest throughout the basin and showed largest spatial variability. Longitudinal distribution of sensitivity coefficients for air temperature, relative humidity and sunshine hours was also found, which was similar to the distribution of the three climate variables.     

Landscape Effects of Land Consolidation Projects in Central China——A Case Study of Tianmen City,Hubei Province

The goal of land consolidation in China is still to develop agricultural production. The study of landscape effects of land consolidation projects （LCPs） faces many difficulties because of the lack of government＇s interest and data. This paper, taking Tianmen City of Hubei Province in Central China as an example, presents a methodology for analyzing landscape effects of LCPs by GIS and Fragstats3.3. It describes landscape effects with indexes of Patch Density （PD）, Largest Patch Index （LPI）, Landscape Shape Index （LSI）, Interspersion and Juxtaposition Index （IJI）, Aggregation Index （AI）, and Shannon＇s Diversity Index （SHDI）, showing more regular shape, simpler structure and less habitat diversity after LCPs. It computes ten landscape indexes of four categories of patches including Cultivated Land, Road, Water Channel, and River and Pond. The indexes show that 1） cultivated land becomes more fragmental in patch area, less irregular in patch shape and more concentrated in block; 2） the transport capacity of roads and irrigation and drainage capacity of water channels have been improved; 3） the landscape change of river and pond can be summarized as decreasing scale, more regular shape, reducing connectivity and diversity of the class. LCPs can facilitate agricultural production as well as protect cultivated land and food security. However, it is doubted that the increase of cultivated land from LCPs results from the reducing in landscape diversity of water area.     

1∶600万《中国自然环境系列地图》挂图编制出版

全国性自然环境系列地图挂图不仅可以为中学和大专院校提供地理教学之用,而且也为政府机关和研究单位以及广大读者了解全国自然条件与自然环境提供形象直观的图形显示。国外对编制与出版全国性自然环境系列地图挂图非常重视,有些国家还编制出版了多种中小比例尺的全国自然环境系列地图。例如早从20世纪50年代开始,前苏联先后编制出版了1∶500万、1∶400万、1∶1000万和1∶250万苏联自然条件系列挂图,包括地势、地质、地貌、土壤、植被、森林等六幅地图。波兰于20世纪70年代编制出版了1∶20万波兰环境系列地图。澳大利亚、法国、德国、美国、日本、匈牙利、西班牙等许多国家也都出版了自然条件或自然环境系列挂图。     

盛世国土——礼贺国土资源部十年华诞

21世纪是中国的世纪。中国学者认为:21世纪,中国现代化的最大问题是农民问题,而中国农民的最大问题则是土地问题。土地的最大问题就是财产权的归属问题,其归根结底是土地制度的深化改革。诞生于20世纪末的国土资源部,是在新一轮"圈地风"再次为中国本来就少得可怜的耕地保护频频亮"红灯"的大势下,在国务院"机构改革"的大盘中应运而生。此次国务院部委机构改革力度之大,为改革后20年之最,将40个机构并减至29个。由原地质矿产部、国家土地管理局、国家海洋局、国家测绘局合并组建中华人民共和国国土资源部。新成立的国土资源部是个"大部",应该说,这是中国共产党和中国政府对土地的眷眷深情演变成对土地的高度重视,此举必将会把国土资源管理水平推向新的高度。     

汶川地震，痛定思痛

5·12汶川大地震,地动大半个中国,牵动亿万中国人的心,撼动全世界,令全世界富有同情心的人都为之动容.大灾大难考验着改革开放30年来的中国政府应对突发灾难的快速反应能力,也考验着一个民族在灾难面前的自信和坚定.中国人民空前的一致,万众一心、众志成城,义无反顾地投身到这场抗震救灾的战斗中去.     

中国农村改革30年发展模式的转变

中国农业的发展影响着整个中国经济的发展;中国农村社会的安定牵涉中国全社会的安定;中国农民的权利保障也是每一个中国人在世界民族之林的尊严和地位的反映。从农村改革开始到2003年前后,农村改革以“减弱控制”为主要特征;2004年以后,农村改革以调整国民收入分配结构、扩大农村公共品供应为主要特征。     

以史为鉴做一个清正廉洁的人

在我国五千年的历史长河中,有一些明君贤相、清官廉吏、忠臣义士能够做到清廉自守、节俭奉公、勤政爱民。近代老一辈无产阶级革命家更是光明磊落、大公无私、以身作则、清正廉明、乐于清贫,为我们树立了光辉的榜样。这种优良的品德和高尚的情操,值得我们后人认真学习和深刻领会。近     

狠抓工作促党建 抓好党建促发展

中国共产党从诞生到现在,已经走过了87年的光辉历程.87年来,我们党由小到大、由弱到强,经历了艰难险阻,领导全国人民取得了新民主主义革命的彻底胜利,创造了社会主义革命和建设的光辉业绩.