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启动子是基因表达调控重要的顺式元件,其结构与功能的研究成为分子生物学的研究热点之一.本文介绍了植物基因启动子的研究方法与概况,重点综述了藻类基因启动子的研究现状,以及本实验室对节旋藻藻蓝蛋白基因启动子的研究情况,并就启动子研究在基因工程中的应用价值和存在问题进行了讨论. 相似文献
254.
pCO2 and carbon fluxes across sea-air interface in the Changjiang Estuary and Hangzhou Bay 总被引:1,自引:0,他引:1
Partial pressure of CO2(pCO2) was investigated in the Changjiang(Yangtze River) Estuary,Hangzhou Bay and their adjacent areas during a cruise in August 2004,China.The data show that pCO2 in surface waters of the studied area was higher than that in the atmosphere with only exception of a patch east of Zhoushan Archipelago.The pCO2 varied from 168 to 2 264 μatm,which fell in the low range compared with those of other estuaries in the world.The calculated sea-air CO2 fluxes decreased offshore and varied from -10.0 to 88.1 mmol m-2 d-1 in average of 24.4 ± 16.5 mmol m-2 d-1.Although the area studied was estimated only 2 × 104 km2,it emitted(5.9 ± 4.0) × 103 tons of carbon to the atmosphere every day.The estuaries and their plumes must be further studied for better understanding the role of coastal seas playing in the global oceanic carbon cycle. 相似文献
255.
Survey of yellowfin tuna in the west-central Indian Ocean was conducted on board of Chinese Iongliners during 2003, 2004 and 2005, which is a part of Chinese Tuna Fishery Scientific Observer Program (CTFSOP). The reproductive biology has been investigated. A total of 1023 samples are collected including 417 ovaries and 606 testes. Spawning activities of yellowfin tuna have been studied for both male and female from January to June. The data showed that the average monthly sex ratio is 0.59, and the minimum length at sexual maturity is 101 cm for female and 110 cm for male respectively. Length at 50% sexual maturity is esti- mated at 113.77 cm for female and 120.20 cm for male, whereas maturation rate is 0.066 cm-1 for female and 0.091 cm-1 for male. Sex ratio by length class indicates that the proportion of male is higher than female's along with size increasing; for instance, in the group of the body length longer than 145 cm, some females have their body length from 145 to 160 cm and males have their body length at 160 cm and even longer. Statistically, yellowfin tuna has a significant seasonal reproduction. 相似文献
256.
地理信息系统(GIS)因为其强大的空间数据处理能力,为水资源管理提供了一个新颖、高效、具有良好可视化效果的管理与应用工具.在与水资源管理专业人员的多次调研、分析基础上,我们基于自主产权版本的Geo-Windows(地学之窗)GIS软件平台开发了一套水资源管理信息试验系统.该系统充分发挥了地理信息系统所具有的地图图面直观、反应快捷、易操作、查询方便、分析功能强大等功能,使水资源管理工作更趋完善,更具有合理性和科学性,可以为领导的辅助决策提供依据. 相似文献
257.
在地理学的文化转向思潮中,记忆研究逐渐受到地理学者的重视。在全球化时代,不同地方的文化将突破时空界限,在广域范围内形成全方位的沟通、交流与互动。本研究对1990至2017年国内外有关乡村记忆的研究文献进行梳理和评述。结果发现:①记忆是多学科的研究议题,近年来逐渐受到地理学者的关注。不同于国外重视对地方、景观等记忆的空间感知研究,国内更关注人对曾经生活过的地方的情感依恋。②乡村记忆作为一种地方性表达,在理性语境中与全球互动融合的同时也逐渐消解,急需进行保护与传承。③本文尝试从范式、视角、尺度、理论、内容和方法层面初步建立乡村记忆地理的研究体系,未来研究应从服务国家战略、推动地理学主导的学科交叉、构建理论体系、拓展全球-地方视阈内容集成、运用多元分析方法等方面加以深化,以期为乡村理论研究和实践发展提供有力的支撑。 相似文献
258.
Li brines are the primary resources for Li salt industries. Evaporation is necessary to concentrate Li due to its low level of concentration in raw brines. The salt sequences during the evaporation of Li brines,especially the behavior of Li salts,represent key data for solar technologies. However,chemists cannot use any phase diagram to estimate Li salt sequences during evaporation at 25℃ . The thermodynamic model proposed by us in2003 represents the only tool for the prediction of equilibrium conditions during the evaporation of solutions containing Li~+,Na~+,K~+,Mg~(2+)/Cl~-,SO_4~(2-),and-H_2 O components at 25℃ . In this paper,the predicted salt sequences of 20 brines are reported. The results indicate that( 1) the first crystallized Li salt during evaporation of Li brine varies in brine composition;( 2) lithium sulfate is crystallized in many cases initially for brines of magnesium sulfate subtype,while Db4( Li_2 SO_4·K_2 SO_4) or Db3( 2 Li_2 SO_4·Na_2 SO_4·K_2 SO_4) appears first for sodium sulfate and magnesium sulfatesubtypes with lower Mg/Li composition,and the final eutectic point is H ~+ LiC ~+ Lc ~+ Ls ~+ Car;( 3) the final eutectic point is H ~+ LiC ~+ Lc ~+ Car for brines of chloride type; and( 4) Li content corresponding to the first crystallized Li salt is in the range of 0. 43%-1%. These findings enhance our knowledge of Li chemistry and provide insights into solar pond technology of the Li-brine process. 相似文献
259.
Hyporheic zone(HZ) influences hydraulic and biogeochemical processes in and alongside streams, therefore, investigating the controlling geographic factors is beneficial for understanding the hydrological processes in HZ. Slack water pool (SWP) is an essential micro-topographic structure that has an impact on surface water and groundwater interactions in the HZ during and after high flows. However, only a few studies investigate HZ surface water and groundwater exchange in the SWP. This study used the thermal method to estimate the HZ water exchange in the SWP in a segment of the Weihe River in China during the winter season. The findings show that on the flow-direction parallel to the stream, river recharge dominates the HZ water exchange, while on the opposing flow-direction bank groundwater discharge dominates the water exchange. The water exchange in the opposing flow-direction bank is about 1.6 times of that in the flow-direction bank. The HZ water exchange is not only controlled by flow velocity but also the location and shape of the SWP. Great water exchange amount corresponds to the shape with more deformation. The maximum water exchange within the SWP is close to the river bank where the edge is relatively high. This study provides some guidelines for water resources management during flooding events. 相似文献
260.
宋长青 《地理学报(英文版)》2019,(9):1437-1440
Research on ecological-hydrological processes in arid/semiarid environments mainly focuses on the following aspects: 1) evolution of the current environments,2) impacts of hu? man activities and climate change,and 3) sustainable development.In the last decades,with the support of China's top science and research agencies/institutes (e.g.,Ministry of Science and Technology,MOST;National Science Foundation China,NSFC;Chinese Academy of Science,CAS),multiple integrated research projects that aim to address the above issues have been initiated from both engineering and scientific perspectives.For example,supported by the NSFC's "China's Western Region Environment and Ecology Science Research Project",in China's northwest arid region,Loess Plateau region and the southwest karst region,four key research themes have been proposed: 1) evolution and development of China's western environment,2) water cycle and sustainable use of water resources,3) ecosystem sustainability,and 4) the impact of major constructions/projects on the environment.In addition,“Heihe River Basin Integrated Water Resources Management Research Project" has been the key research project supported by the CAS,which aims to improve water use efficiency,sustain the oasis ecosystem,develop the integrated irrigation water technology,improve water resources management,protect wetland and help with the river basin water management and decision making. 相似文献