分类： 数字出版 >> 新媒体 提交时间： 2024-05-24 合作期刊: 《Research in Astronomy and Astrophysics》
摘要： From the mid-19th century to the end of the 20th century, photographic plates served as the primary detectors for astronomical observations. Astronomical photographic observations in China began in 1901, and over a century, a total of approximately 30,000 astronomical photographic plates were captured. These historical plates play an irreplaceable role in conducting long-term, time-domain astronomical research. To preserve and explore these valuable original astronomical observational data, Shanghai Astronomical Observatory has organized the transportation of plates, taken during nighttime observations from various stations across the country, to the Sheshan Plate Archive for centralized preservation. For the first time, plate information statistics were calculated. On this basis, the plates were cleaned and digitally scanned, and finally digitized images were acquired for 29,314 plates. In this study, using Gaia DR2 as the reference star catalog, astrometric processing was carried out successfully on 15,696 single-exposure plates, including object extraction, stellar identification, and plate model computation. As a result, for long focal length telescopes, such as the 40 cm double-tube refractor telescope, the 1.56 m reflector telescope at Shanghai Astronomical Observatory, and the 1m reflecting telescope at Yunnan Astronomical Observatory, the astrometric accuracy obtained for their plates is approximately
分类： 生物学 >> 生态学 提交时间： 2018-02-01 合作期刊: 《生态学报》
摘要： 水体营养元素是影响水体生态系统的重要因素，决定着水体中不同的浮游生物群落结构，也是评价水质和水体营养状态的重要指标。对太原汾河蓄水区9个样点浮游植物和各项水环境及营养元素进行了调查与分析，调查期间发现（1）该流域蓝藻和绿藻为主要优势类群，即构成了以蓝-绿藻门为主要的浮游群落。平水期与丰水期优势种均以蓝藻门的微小色球藻（Chroococcus minutus）、微小平裂藻（Merismopedia tenuissima）、小颤藻（Oscillatoria tenuis）、铜绿微囊藻（Microcystis aeruginosa）为主，其丰度分别占平水期和丰水期藻细胞总数的42.95%和59.24%。叶绿素a含量随地理位置变化明显，中下游显著高于上游。（2）太原汾河蓄水区水质均达到富营养状态。由于太原汾河蓄水区沿途的生活垃圾、污水的不合理排放，导致汾河中总氮、总磷等指标偏高，最终导致整个水体处于轻度富营养状态或中度富营养状态。（3）叶绿素a含量与水温、总氮、总磷呈显著正相关，与有机物含量呈极显著正相关，总磷的影响最为明显，说明磷可能是该地区浮游植物生长的限制因子。
点击量
通过
点击量
下载量
评论
