我国人口资源与食物问题

人口增多,耕地减少,部分地区供水不足,是我国人口与资源矛盾的基本格局。由于人口的压力,对资源实行超强度的利用,使较大范围的地区生态环境恶化,严重威胁农业生产,并成为许多地区多灾、低产、贫困的根本原因,较低的食物人均占有水平,将继续成为中国国民经济发展和人民生活水平提高的严重限制因素。增加食物,必须挖掘资源的潜力,开源与节流相结合,以内涵挖潜为主。首先是要立足现有的耕地,致力于提高单产;同时,合理开发水域、山地、草地等资源,广辟食物来源,提高非耕地资源的生产力,提高林牧渔业的发展水平。耕地应以深度开发为主,走资源节约型(节地、节水、节时、节能)的集约化道路。     

Ecophysiological indicators of the state of animal populations exposed to damaging factors

Indices of abundance and reproduction rate are considered in some groups of aquatic and terrestrial vertebrates from the zones of technogenic disasters. Upon a critical population decline caused by external destructive factors, such as emissions of acute ecotoxicants, the ecophysiological and behavioral compensatory mechanisms are activated, which provide for restoration of the total population size to the optimum within a short period of time. Environmental pollution with substances disturbing the reproductive function has the gravest consequences for animals. In this case, population size may remain fairly high, and, therefore, the effect of enhanced reproduction as a response to population decline does not take place, which eventually leads to a gradual but irreversible destruction of the population. Pathologies of reproduction should be used as a criterion for assessing the state of animals in the zones of technogenic disasters.Translated from Ekologiya, No. 1, 2005, pp. 32–38.Original Russian Text Copyright © 2005 by Shilova, Shatunovskii.     

An approach to the fluctuation mechanism of ecotone

In this paper,the relationship among land productivity,population pressure and the fluctuation mechanism of ecotone is analyzed,taking coumties and banners of southeast Inner Mongolia plateau as an example,which is the most fragile part in the farming and husbandry interleaving belt of north China due to its severe desertification degree and low level of economic development.The Cv for the total output value of agriculture decreases from southeast to northwest,with the same rule as which the overloading population cumulated distributes,and both indicators have close relation with the high linear coefficient of 0.83.These reveal the fluctuation mechanism for ecotone:fluctuation of the level of economic development is a scientific and practical measure both to weakness degree and to instability of ecotone,because it is a synthesized response to the variation of climate as well as irrational land uses,which reinforce and magnify the fluctuation.In detail,the heavier the population overloading,the severer the grassland reclamation,the stronger the dependence of regional productivity on rainfall,the lower the level of economic development,the rougher the fluctuation of ecotone,but the weaker the PRED system.     

区域土地资源承载能力研究模式雏议——以甘肃省定西县为例

本文从土地现实生产力分析和作物潜在生产力估算入手,借助IBM-PC计算机,通过土地资源生产力评价的 MFICA 模式和土地资源优化利用模型的建立,初步框算了定西县1990年、2000年,2025年以及2050年之后的区域农业生产力及其土地资源承载力,进尔阐释了该县土地资源承载力的演变及其土地-粮食-人口关系的可能发展趋势。为区域土地资源承载力研究提供了一条切实可行的途径。     

Pulse cleaning flow models and numerical computation of candle ceramic filters

ＩｎｔｒｏｄｕｃｔｉｏｎＣｌｅａｎｉｎｇｔｈｅｆｉｎｅｐａｒｔｉｃｌｅｓｉｎｈｉｇｈｔｅｍｐｅｒａｔｕｒｅ (450℃ -950℃ )ａｎｄｈｉｇｈｐｒｅｓｓｕｒｅｃｏｎｄｉｔｉｏｎｃａｎｅｎｈａｎｃｅｔｈｅｔｈｅｒｍａｌｅｆｆｉｃｉｅｎｃｙｏｆｃｌｅａｎｃｏａｌｔｅｃｈｎｏｌｏｇｉｅｓｓｕｃｈａｓＩＧＣＣｏｒＰＦＢＣ .Ｒｉｇｉｄｃｅｒａｍｉｃｆｉｌｔｅｒｓｏｆａｖａｒｉｅｔｙｏｆｓｔｒｕｃｔｕｒｅｓａｒｅｕｎｄｅｒｄｅｖｅｌｏｐｍｅｎｔｉｎｐｒｏｇｒａｍｓａｒｏｕｎｄｔｈｅｗｏｒｌｄ ,ｗｈｉｃｈｃａｎｆｉ…     

以最经济输水为原则 调整高压输水泵及工艺

简这了炼油厂更新高压输水泵，调整输水工艺、降低输水成本的方法。     

Intrauterine manometry: Technique and application to fetal pathology

A technique is described for measuring pressure within the amniotic cavity and within fetal vessels and/or body compartments. Two saline-filled catheters were connected at one end to needles inserted during indicated invasive procedures and at the other to silicon strain gauge transducers. In 36 pregnancies with normal liquor volume, stable intra-amniotic pressure (IAP, range 1–14 mmHg) increased with gestation (r=0·48, p<0·01). In pregnancies complicated by severe oligohydramnios, IAP was ≤ 1 mm Hg and rose to normal levels with saline amnioinfusion. Raised IAP (range 17–26 mm Hg), found in pregnancies with gross polyhydramnios, fell with drainage of amniotic fluid. Subtraction manometry was used to determine supra-amniotic pressure within the intervillus space, umbilical vein, umbilical artery, abdominal and thoracic cavities, and the urinary tract in normal and/or pathological fetuses. Low intravesical and intrapelvicalyceal pressures (median 6·5, range 2–10 mmHg) were noted in fetuses with obstructive uropathies. Intrauterine subtraction manometry appears to be a useful tool in the understanding of fetal pathophysiology and may be of clinical benefit in the therapeutic drainage and infusion of amniotic fluid and in the assessment of certain fetal disease states.     

基于风险的检验在高温高压管廊蒸汽管道的应用

高含硫天然气净化装置高温高压管廊蒸汽管道由于不能停车,在现有技术条件下无法开展全面检验,存在安全运行的风险。简述了基于风险的检验技术的基本理念。讨论了蒸汽管道开展基于风险的检验的合规性、损伤模式及机理、风险评估方法和程序。通过综合考虑失效可能性和失效后果,制定最优检验策略并实施,解决了高温高压管廊蒸汽管道到期不能检验的问题,及时发现隐患并整改,确保管道合法合规安全运行。研究结果表明,采用基于风险的检验技术,既能节约大量的停车和检验维修费用,又能有效地提高重点设备管线的安全性和管理水平。     

铁路环境噪声对居民冲击影响的模糊综合评价

铁路环境噪声对居民的冲击影响程度不仅与列车运行辐射噪声级有关，而且还与人口密度，及白天、夜间的人口比例等因素有关。考虑以上诸多因素，采用模糊综合评价方法进行铁路环境噪声对居民的冲击影响的综合比较评价，并通过实例验证了该方法的有效性和可靠性，为铁路环境噪声评价提供了新的方法。