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21.
盐藻和β-胡萝卜素研究述评 总被引:11,自引:0,他引:11
养殖盐藻生产β-胡萝卜素是近十几年新兴起的研究领域,因其应用前途广阔,现已成为微藻生物学的研究前沿和热点,预计本世纪末和下世纪初将有更大发展。鉴于我国在这方面文章不系统,不全面,本文从盐藻生物学,养殖学,β-胡萝卜素异构体,β-胡萝卜素形成生理等角度全面概念了该领域研究现状,并提出存在的问题与研究方向。 相似文献
22.
Siqi Ma Weiwei Chen Shichun Zhang Quansong Tong Qiuyang Bao Zongting Gao 《中国地理科学(英文版)》2017,27(6):989-1002
Northeast China has been reported as having serious air pollution in China with increasing occurrences of severe haze episodes. Changchun City, as the center of Northeast China, has longstanding industry and is an important agricultural base. Additionally, Changchun City has a long winter requiring heating of buildings emitting pollution into the air. These factors contribute to the complexity of haze pollution in this area. In order to analyze the causes of heavy haze, surface air quality has been monitored from 2013 to 2015. By using satellite and meteorological data, atmospheric pollution status, spatio-temporal variations and formation have been analyzed. Results indicated that the air quality in 88.9% of days exceeding air quality index(AQI) level-1 standard(AQI 50) according to the National Ambient Air Quality Standard(NAAQS) of China. Conversely, 33.7% of the days showed a higher level with AQI 100. Extreme haze events(AQI 300) occurred frequently during agricultural harvesting period(from October 10 to November 10), intensive winter heating period(from Late-December to February) and period of spring windblown dust(April and May). Most daily concentrations of gaseous pollutants, i.e., NO_2(43.8 μg/m~3), CO(0.9 mg/m~3), SO_2(37.9 μg/m~3), and O_3(74.9 μg/m~3) were evaluated within level-1 concentration limits of NAAQS standards. However, particulate matter(PM_(2.5) and PM10) concentrations(67.3 μg/m~3 and 115.2 μg/m~3, respectively) were significantly higher than their level-1 limits. Severe haze in spring was caused by offsite transported dust and windblown surface soil. Heavy haze periods during fall and winter were mainly formed by intensive emissions of atmospheric pollutants and steady weather conditions(i.e., low wind speed and inversion layer). The overlay emissions of widespread straw burning and coal combustion for heating were the dominant factors contributing to haze in autumn, while intensive coal burning during the coldest time was the primary component of total emissions. In addition, general emissions including automobile exhaust, road and construction dust, residential and industrial activities, have significantly increased in recent years, making heavy haze a more frequent occurrence. Therefore, both improved technological strategies and optimized pollution management on a regional scale are necessary to minimize emissions in specified seasons in Changchun City, as well as comprehensive control measures in Northeast China. 相似文献
23.
小黄鱼(Pseudosciaena polyactis)形态性状与体质量的相关性及通径分析 总被引:4,自引:0,他引:4
为了研究野生小黄鱼(Pseudosciaena polyactis)繁殖后代的形态性状对体质量的影响作用,以随机采集的729尾4.5月龄小黄鱼为研究对象,对每尾个体的体质量(g)和8个形态性状(cm):全长(X1)、体长(X2)、头长(X3)、躯干长(X4)、尾部长(X5)、尾柄长(X6)、尾柄高(X7)和体高(X8)进行准确测定,运用相关分析、多元回归分析和通径分析方法,分别计算性状间的相关系数、构建形态性状与体质量的多元回归方程,获得了通径系数和决定系数,进行了养殖小黄鱼的形态性状对体质量的影响研究。结果显示,8个形态性状与体质量的相关系数均达到极显著水平(P0.01);通径分析中,4个形态性状对体质量的通径系数达到极显著水平(P0.01),它们是影响体质量的重要指标,其中体长(通径系数:0.589)对体质量的直接影响最大。应用逐步多元回归分析建立了以体质量为因变量(Y),体长(X2)、躯干长(X4)、尾柄高(X7)和体高(X8)为自变量的回归方程:Y=–32.377+3.064X2–1.511X4+14.285X7+4.438X8。模型等式中形态性状与体质量的相关指数R2=0.927,说明所选性状是影响体质量的主要形态性状。以上分析结果为小黄鱼的选育测量指标的确定提供了理论依据。 相似文献
24.
天津市地震前兆台网的运行监控与维护管理 总被引:8,自引:0,他引:8
介绍天津市地震前兆台网的基本概况以及前兆台网部的职责任务;阐述仪器设备运行监控、观测数据质量监控的方式与方法;总结在仪器设备、技术系统维护过程中解决的一些关键技术问题;最后提出了关于仪器和软件系统的一些问题与建议。 相似文献
25.
Bao Yang Achim Bruning Jingjing Liu Mary E. Davis Shao Yajun 《Global and Planetary Change》2009,69(1-2):71-78
The climatological signal of δ18O variations preserved in ice cores recovered from Puruogangri ice field in the central Tibetan Plateau (TP) was calibrated with regional meteorological data for the past 50 years. For the period AD 1860–2000, 5-yearly averaged ice core δ18O and a summer temperature reconstruction derived from pollen data from the same ice core were compared. The statistical results provide compelling evidence that Puruogangri ice core δ18O variations represent summer temperature changes for the central TP, and hence regional temperature history during the past 600 years was revealed. A comparison of Puruogangri ice core δ18О with several other temperature reconstructions shows that broad-scale climate anomalies since the Little Ice Age occurred synchronously across the eastern and southern TP, and the Himalayas. Common cold periods were identified in the 15th century, 1625–1645 AD, 1660–1700 AD, 1725–1775 AD, 1795–1830 AD, 1850–1870 AD, 1890–1920 AD, 1940–1950 AD, and 1975–1985 AD. The period 1725–1775 AD was one of the most prolonged cool periods during the past 400 years and corresponded to maximum Little Ice Age glacier advance of monsoonal temperate glaciers of the TP. 相似文献
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27.
YANG Zisheng LIU Yansui BAO Guangjing LI Zhiguo HE Yimei 《山地科学学报》2006,3(3):237-246
The rocky desert in a karst area directly causes the lack of soil, water and forest, hence leading to the poverty there. In 1990, the villagers from the Muzhe Village in Benggu Township, Xichou County, Yunnan declared a war against rocky desert in an attempt to ask the fields for more yields. They invented a distinctive land rehabilitation and sustainable use pattern called "transforming heaven and earth" that had been practiced in Southwest China's karst areas. The key mechanism of the pattern was to develop terraced fields with well conserved soil, water and fertility by exploding rocks in the fields, building stone walls, gathering more soil, and improving soil quality and productivity for the fields in combination with building of irrigation facilities and roads, as well as with forestation and agriculture structure adjustment. The purpose of the pattern was to alleviate poverty in the karst areas by improving soil productivity and promoting agricultural development. A typical area was studied with the help of Participatory Rural Appraisal (PRA) and the pattern was carried out there for fifteen years, have produced excellent ecological benefits and good economic benefits. Its application in the area approved that it was a sustainable land use pattern for rocky desert areas. 相似文献
28.
为探讨星康吉鳗(Conger myriaster)精子的超微结构和形态,应用扫描电镜和透射电镜对星康吉鳗精子结构进行观察。结果表明,精子由头部、中段和鞭毛3部分组成,有其独特的结构,总长度为35.75± 1.15µm。精子头部为新月形,主要由细胞核构成,细胞核内有核泡,无顶体结构。精子头部的质膜内包含单一的线粒体。精子头部长为3.33±0.16 um,头宽为1.12±0.13 um。在精子头部的凸面上,有4条从中段到头端的条纹。精子中段伸出一支根,支根位于精子的中段末端。精子中段长度为0.55±0.05 um,支根长度为1.38±0.08 um、直径为90.48±6.06 nm。精子尾部鞭毛细长,鞭毛横切面呈圆形,无侧鳍,鞭毛的轴丝结构为“9+0”型;一些鞭毛的末端呈现卷曲状,发育机制尚不明确。精子鞭毛长为31.16±1.51µm,鞭毛直径为0.17±0.01µm。通过比较分析发现精子的这些形态学特征不仅表现在星康吉鳗精子,还表现在鳗鲡目其他属的精子;表明是鳗鲡目精子的共同特征。本研究揭示了星康吉鳗精子的形态结构,为突破星康吉鳗人工繁殖技术提供了理论参考。 相似文献
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利用陆面过程模式BATS,引入地表发射率及两种大气发射率参数化方案,同时引入不同的地表粗糙度参数化方案,对比各种参数化方案对沙漠下垫面地面温度及能量收支的模拟状况。结果表明:采用Van Bavel等发展的地表发射率及Chung等发展的大气发射率方案可以明显改进地面温度及向上长波辐射的模拟,Chung等方案在夜间与正午的模拟效果更好,减小了1 ℃左右的地面温度模拟偏差,减小了10 W·m-2左右的向上长波辐射模拟偏差。晴天地面温度及向上长波辐射的模拟结果优于阴天。利用Zhang等发展的裸土粗糙度参数化方案也会提高模式对地表感热通量模拟的准确性。 相似文献