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自2007年《注册测绘师制度暂行规定》颁布实施以来,虽然已有近2万人取得注册测绘师职业资格,然而我国注册测绘师仍然很难按照制度设计的初衷,在测绘项目管理或生产管理中发挥实效。本文将对当前注册测绘师面临的执业困境进行深入剖析,从政策体系的不完善、产业融合带来恶性竞争、人员分布不均造成局部的短缺和局部拥挤等多方面进行分析,并从健全国家、企业、个人“三位一体”监管体系、着力强化综合监管、总结试点经验、实施签字盖章制度等方面提出自己的建议。 相似文献
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国家一级保护动物中华鲟(Acipenser sinensis)自然繁殖已连续中断3年(2017 2019年),自然种群濒临灭绝.本文归纳了中华鲟生活史各阶段的生态需求,指出:葛洲坝阻隔是导致中华鲟自然种群衰退的根本原因,三峡等长江上游特大型梯级水电工程的相继蓄水运行是导致中华鲟自然繁殖中断的关键因素,河道冲刷、航道疏浚与挖沙、防洪及城市景观工程等人类活动使中华鲟仔稚鱼栖息地丧失,进而导致补充群体减少,造成繁殖群体持续萎缩.近40年来,对给予高度期望的补偿中华鲟自然种群衰退的中华鲟人工增殖放流措施没有得到科学有效地实施,造成人工干预力保中华鲟自然种群延续的希望几近破灭.本文探讨了近40年来在中华鲟保护认识、管理、决策和机制上存在的误区与不足,提出以长江十年休渔为契机,亟需以《中华鲟拯救行动计划(2015-2030年)》为纲领,推进落实:1)实施"陆-海-陆"保种工程,恢复人工群体的生物学自然特性; 2)大幅度提升科学有效的人工增殖放流; 3)改善产卵场环境,放流人工培育亲本以恢复葛洲坝下中华鲟自然繁殖; 4)新建旁通道仿自然产卵场,扩大自然繁殖; 5)修复索饵场等关键栖息地,提高子代存活率.唯有以恢复中华鲟自然繁殖为核心,实施中华鲟从出生到繁殖全生活史周期(15年)的长期系统性保护,才有望延续和恢复中华鲟自然种群.中华鲟个体大、寿命长、洄游范围广,是长江水生态系统的旗舰种和伞护种,保护好中华鲟对于实现人与自然和谐共处,推动长江流域经济社会绿色可持续发展具有重要意义. 相似文献
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We study the effect of accumulative payoff on the evolution of cooperation in the evolutionary prisoner's dilemma on a square lattice. We introduce a decaying factor for the accumulative payoff, which characterizes the extent that the historical payoff is accumulated. It is shown that for fixed values of the temptation to defect, the density of cooperators increases with the value of the decaying factor. This indicates that the more the historical payoff is involved, the more favourable cooperators become. In the critical region where the cooperator density converges to zero, cooperators vanish according to a power-law-like behaviour. The associated exponents agree approximately with the two-dimensional directed percolation and depend weakly on the value of the decaying factor. 相似文献
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In 1859, in his great work On the Origin of Species, Darwin repeatedly raised what he regarded to be the most serious problem facing his theory of evolution – the lack of fossils predating the rise of shelly invertebrates that marks the beginning of the Cambrian Period of geological time (550 Ma), an “inexplicable” absence that could be “truly urged as a valid argument” against his all-embracing synthesis. This missing early fossil record posed a major dilemma, for Darwin's theory demanded firm linkage from the less advanced to the more evolved, from primitive microbes to protozoans to the rich faunas of the basal Phanerozoic for which no fossil evidence was known. For more than 100 years, the history of Precambrian life stood out as one of the greatest unsolved problems in natural science. In recent decades, however, understanding of life's early evolution has changed markedly as the documented fossil record has been extended seven-fold to some 3500 Ma, an age more than three-quarters that of the planet. This long-sought solution to Darwin's dilemma was set in motion by a small vanguard of workers who blazed the trail in the 1950s and 1960s, just as their course was charted by a few prescient pioneers of the previous century. All workers today, including the 28 participants in the recently held World Summit on Ancient Microscopic Fossils, have roots that can be traced to the pathfinders of a half-century ago. 相似文献
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本文通过对城镇化背景下,农村宅基地闲置现状的分析,归纳出目前农村宅基地退出在传统观念、产权界定、引导机制、政府定位和补偿标准收益分配上的困境,进而探讨了如何建立完善的宅基地退出机制。 相似文献
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