天然沸石在畜牧业及家禽业方面的应用

天然沸石在畜牧业及家禽业方面的应用Ｇ。Ｖ。ＴｓｉｔＳｉｓｈｖｉｌｉＴ。Ｇ。ＡｎｄｆｏｍｋａＳｈｖｉｌｉ６。Ｎ。ＫｉｒｏｖＬ，Ｄ，Ｆｉｌｉｚｏｖａ６０年代的研究和试验，已经开始考虑到利用天然沸石（主要是斜发沸石）作为添加剂饲养家禽、猪和牛。最初的报道之...     

第一届计算机地图制图学术讨论会在南京召开

中国地理学会和中国测绘学会联合召开的第一届计算机地图制图学术讨论会于1984年2月23日至29日在南京举行。这次学术讨论会是在新的技术革命高潮中,对计算机和信息系统在现代化建设事业上提出了更高要求的前     

CHARACTERISTICS OF SOUND PULSETRANSMISSION IN SHALLOW SEA ANDCORRELATION DETECTION

Statistical characteristics of sound pulses and some typical marine noises in a shallow sea were analysed. With special requirements for underwater telemetric and telecontrolled devices in mind,a specific signal processing scheme ( digital correlation accumulation ) is put forward. Theoretical analyses on some underwater acoustic instruments showed this signal processing scheme is applicable to a shallow acoustic channel with variable spatiotemporal characteristics, multipath pulses and high noise level, and may be of general significance for underwater acoustic telemetry and telecontrol.     

基桩承载特性的位移协调法分析研究

介绍了利用位移协调法分析基桩承载特性的理论基础及计算方法。根据郑州某工程的静载试验资料，求得桩身荷载的传递函数，并利用该函数对基桩承载特性进行了分析。得出了可利用实测传递函数对同一场地的不同桩长、桩径或具有相同工程地质条件的不同场地的基桩进行承载特性分析的结论，以及桩端土层的力学指标和桩身弹模的选取对计算结果有较大影响的结论。     

厄尔尼诺现象和闽浙沿岸夏季表层盐度值的变异

一、引言近年来,笔者曾探讨过厄尔尼诺现象和在闽南—台湾浅滩渔场上升流演变的关系,发现了在厄尔尼诺年夏季(除了次级厄尔尼诺年如1969年和厄尔尼诺年如1965,1966年8—9月外),在东山站出现表层盐度(按月平均值)较低。众所周知,厄尔尼诺现象是一种非周期性,全球性的海—气异常现象,不会仅局限于某一站水文要素异常的变化,也许还会涉及范围广些,闽浙沿岸夏季表层盐度变化规律如何?与厄尔尼诺现象有关? 日前人们对于厄尔尼诺现象预报还没有找到切实可行方法,还在很艰苦探索中。但是,为     

北宋中期耕地面积及其空间分布格局重建(英文)

To understand historical human-induced land cover change and its climatic effects, it is necessary to create historical land use datasets with explicit spatial information. Using the taxes-cropland area and number of families compiled from historical documents, we esti-mated the real cropland area and populations within each Lu (a province-level political region in the Northern Song Dynasty) in the mid-Northern Song Dynasty (AD1004-1085). The es-timations were accomplished through analyzing the contemporary policies of tax, population and agricultural development. Then, we converted the political region-based cropland area to geographically explicit grid cell-based fractional cropland at the cell size of 60 km by 60 km. The conversion was based on calculating cultivation suitability of each grid cell using the topographic slope, altitude and population density as the independent variables. As a result, the total area of cropland within the Northern Song territory in the 1070s was estimated to be about 720 million mu (Chinese area unit, 1 mu = 666.7 m2), of which 40.1% and 59.9% oc-curred in the north and south respectively. The population was estimated to be about 87.2 million, of which 38.7% and 61.3% were in the north and south respectively, and per capita cropland area was about 8.2 mu. The national mean reclamation ratio (i.e. ratio of cropland area to total land area; RRA hereafter for short) was bout 16.6%. The plain areas, such as the North China Plain, the middle and lower reaches of the Yangtze River, Guanzhong Plain, plains surrounding the Dongting Lake and Poyang Lake and Sichuan Basin, had a higher RRA, being mostly over 40%; while the hilly and mountainous areas, such as south of Nanling Mountains, the southwest regions (excluding the Chengdu Plain), Loess Plateau and south-east coastal regions, had a lower RRA, being less than 20%. Moreover, RRA varied with topographic slope and altitude. In the areas of low altitude (≤250 m), middle altitude (250-100 m) and high altitude (1000-3500 m), there were 443 million, 215 million and 64 million mu of cropland respectively and their regional mean RRAs were 27.5%, 12.6% and 7.2% respectively. In the areas of flat slope, gentle slope, medium slope and steep slope, there were 116 million, 456 million, 144 million and 2 million mu of cropland respectively and their regional mean RRAs were 34.6%, 20.7%, 8.5% and 2.3% respectively.