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基于机器视觉的水稻印刷播种机成种率检测 被引量:2
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作者 周红标 朱亚文 +2 位作者 刘晓洋 张国良 李边豪 《中国农机化学报》 北大核心 2023年第7期194-199,235,共7页
水稻印刷播种是实现稻种精确定位和均匀播种的有效方法之一。由于机械振动、播种纸走速、稻种输送等环节影响,播种纸的某些胶点上可能会粘附多个水稻种子,影响播种质量。为此,提出基于机器视觉的水稻印刷播种机成种率检测方法。首先,利... 水稻印刷播种是实现稻种精确定位和均匀播种的有效方法之一。由于机械振动、播种纸走速、稻种输送等环节影响,播种纸的某些胶点上可能会粘附多个水稻种子,影响播种质量。为此,提出基于机器视觉的水稻印刷播种机成种率检测方法。首先,利用工业CCD摄像机采集播种纸正面图像信息;其次,利用红绿色差提取种子的颜色信息,采用Otsu阈值分割等形态学处理方法实现种子与背景的分离,并利用开运算实现轻微粘连稻种的分离;然后,利用面积阈值方式去除噪点,从而实现水稻种子数量的统计;最后,根据粘连稻种总面积与每个稻种平均面积的比值对紧密粘连的稻种进行处理,从而修正水稻种子的数量。研究结果表明,该成种率检测方法是有效的,能够从播种纸的胶点上获取水稻种子数量信息,检测的成种率范围介于88.84%~92.05%。 展开更多
关键词 水稻 印刷播种机 机器视觉 自适应形态学 精确定位播种 成种
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物种形成方式及成种理论述评 被引量:7
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作者 同号文 《古生物学报》 CAS CSCD 北大核心 1997年第3期387-400,共14页
物种的形成是生物进化的最根本问题,但谁也没有亲历过自然界物种的形成过程。因此,才会出现数十种不同的成种假说或模式。生物界是极其多样的,物种的形成方式也必然是多样的;过去那种将不同观点对立或进行简单取舍的做法是不对的。... 物种的形成是生物进化的最根本问题,但谁也没有亲历过自然界物种的形成过程。因此,才会出现数十种不同的成种假说或模式。生物界是极其多样的,物种的形成方式也必然是多样的;过去那种将不同观点对立或进行简单取舍的做法是不对的。事实上,不同观点都有一定的代表性。有关成种作用的遗传学实验已进行了近半个世纪,但对自然界中物种的形成问题尚未带来革命性的影响。过去一味地从地理隔离方面来研究成种问题,难免有其局限性;而真正与成种作用关系密切的是繁殖率(或出生率),繁殖率越高,生物间遗传物质的交换和重组的机会就越多,产生变异的机会也就越多,这样就越容易产生新物种。关于物种形成中的中间环节(过渡类型)的问题已争论了近一个世纪,实际上,这是一个由渐变成种论所带来的问题(渐变成种与中间环节的问题);在突变成种中,不需要过渡类型,新旧物种的更替是通过突变共存方式完成的。 展开更多
关键词 物种形成 成种方式
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染色体变异成种说能够推翻达尔文进化论吗?——和赵汉雄先生商榷
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作者 王立忠 王正 《化石》 2002年第2期25-25,共1页
关键词 物种进化 染色体变异 成种 达尔文进化论
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榕-传粉小蜂化学通讯机制研究进展
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作者 杨扬 王嵘 陈小勇 《生态学报》 CAS CSCD 北大核心 2023年第11期4400-4410,共11页
榕属植物与其传粉小蜂组成了高度专一的专性共生关系(榕-蜂共生系统),如此高度紧密的互作关系被认为是驱动两者多样化的关键因素。榕-蜂共生系统主要依靠化学通讯完成相互识别,但目前仍不清楚化学通讯是如何维系现有共生关系并促进物种... 榕属植物与其传粉小蜂组成了高度专一的专性共生关系(榕-蜂共生系统),如此高度紧密的互作关系被认为是驱动两者多样化的关键因素。榕-蜂共生系统主要依靠化学通讯完成相互识别,但目前仍不清楚化学通讯是如何维系现有共生关系并促进物种形成的。结合已有研究,系统梳理了榕-蜂共生系统化学通讯的基础与两者特异性识别的机制,阐述化学通讯在物种和种群层次对维持这一专性传粉关系的重要贡献,进而探讨化学通讯如何在协同成种和宿主转移成种两种模式中介导物种形成。最后,结合生理与多组学等技术展望榕-蜂共生系统的未来研究方向,为深入解析植物与昆虫协同进化的机制以及全球变化下物种的潜在响应模式提供重要参考。 展开更多
关键词 榕和榕小蜂 化学通讯 宿主专一性 协同成种 宿主转移
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Group Size and Composition of Black-and-White Snub-nosed Monkey (Rhinopithecus bieti) Estimated by Faecesof Sleeping Sites at Baima Snow Mountain 被引量:8
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作者 崔亮伟 钟泰 +1 位作者 肖林 肖文 《Zoological Research》 CAS CSCD 北大核心 2006年第4期337-343,共7页
This study was designed to introduce a new method of estimating group size and composition of black-andwhite snub-nosed monkeys (Rhinopithecus bieti ) on the basis of faecal amount at sleeping sites at Mt. Baima Nat... This study was designed to introduce a new method of estimating group size and composition of black-andwhite snub-nosed monkeys (Rhinopithecus bieti ) on the basis of faecal amount at sleeping sites at Mt. Baima Nature Reserve. The monkeys spend nights in the form of one-male, multi-female units (OMUs) and all-male units (AMU), and their faecal pellets can be classified into three categories: adult males (the largest), adult females (moderate) and immatures (the smallest) based on their size. Total pellets were counted under sleeping trees used for two nights at Nanren village (99°04′E, 28°34′N, northwest of Yunnan Province, China) in each of four seasons in 2000- 2001. Moreover, data on group composition were collected when the monkeys were passing through an open gully in November 2001. Since the number of adults in OMUs shows a positive significant correlation with the amount of pellets amount in each season, the mean number of feces produced per night per individual is the slope of the regression lines. Thus, group size and composition can be relatively reliably and accurately estimated by the faeces under trees compared with the previous methods of estimation, including the use of monkeys' activities and tracks such as broken branches on steep slopes, in deep gorges and under lower visibility. The use of pellets for population estimates displayed 9.4% deviation in regards to population size of adult females. Some causes of the bias were also discussed. The method might be applicable to other monkey groups of this species if their habitats and main foods are similar to those of the study group. 展开更多
关键词 FECES Group composition Group size Rhinopithecus bieti Sleeping site
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Callus Induction and Plant Regeneration from Mature Seeds of Perennial Ryegrass 被引量:15
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作者 曾升坚 卞建春 +2 位作者 方钲 张冬霞 邹新海 《Agricultural Science & Technology》 CAS 2009年第6期33-36,共4页
Objective The aim was to explore callus induction and plant regeneration of perennial ryegrass, as well as provide the foundation for transgenic research on perennial ryegrass.[ Methed] Mature seeds of perennial ryegr... Objective The aim was to explore callus induction and plant regeneration of perennial ryegrass, as well as provide the foundation for transgenic research on perennial ryegrass.[ Methed] Mature seeds of perennial ryegrass were used as explants to study the effects of different hormone compositions on callus induction, proliferation and plant differentiation. Result The result showed that the induction rate achieved its highest on 2,4-D of 8 mg/L combining with 6-BA of 0.025 mg/L, which was up to 56.42%. Callus were differentiated after two to three generations, the highest differentiation rate 34.14% was achieved in the medium contained MS medium with 6-BA of 2 mg/L, and the differentiation rate was obviously affected by the callus condition after proliferation. The root inducing medium, containing 0.5 mg/L NAA and MS medium with half of macroelement, gained 98% root inducing rate. Conclusien A high frequency genetic regeneration system was established. 展开更多
关键词 Perennial ryegrass Mature seed: Tissue culture Plant regeneration
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Study on Germplasm Resources of Tartary Buckwheat (Fagopyrum tataricum) in Shanxi Province 被引量:1
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作者 张丽君 马名川 +3 位作者 刘龙龙 康国帅 周建萍 崔林 《Agricultural Science & Technology》 CAS 2016年第5期1217-1222,1270,共7页
This study analyzed the tartary buckwheat recorded in the books Catalogue of Crop Germplasm Resources in Shanxi Province and Catalogue of Chinese Buckwheat Germplasm Resources by Excel 2003 and DPS 7.5 from the aspect... This study analyzed the tartary buckwheat recorded in the books Catalogue of Crop Germplasm Resources in Shanxi Province and Catalogue of Chinese Buckwheat Germplasm Resources by Excel 2003 and DPS 7.5 from the aspects of distribution areas,main agronomic traits and nutritional components,so as to lay a foundation for the selection of excellent buckwheat germplasm resources and improvement of buckwheat varieties.The results showed that different buckwheat varieties vary in plant height,node number of the main stem,grain weight per plant,grain weight per plant and kilo-grain weight.Compared with the national average values,buckwheat in Shanxi is higher in protein and fat,but lower in vitamin E and vitamin PP;it is rich in Ca,Mg,Cu,P,Se,Fe,Mn and Zn;and it contains 18 amino acids with the content of glutamic acid being the highest and the content of tryptophane being the lowest.After analyzing and classifying the tartary buckwheat germplasm resources recorded in Catalogue of Grop Germplasm Resources in Shanxi Province and Catalogue of Chinese Buckwheat Germplasm Resources,breeders could breed new varieties with high yield and quality and strong stress resistance by crossbreeding with these germplasm resources. 展开更多
关键词 Tartary buckwheat Agronomic traits Nutritional composition Germplasm resources SHANXI
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大进化理论及其与小进化理论的争论
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作者 张景华 《辽宁师范大学学报(自然科学版)》 CAS 1990年第4期35-39,共5页
本文主要讨论了大进化理论的基本内容、研究范围,及其与传统的小进化理论间争论的一些焦点问题,并对这一争论在进化生物学领域中所产生的积极影响,作了简要的分析。
关键词 生物进化 成种作用 大进化 小进化
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论多细胞物种的进化机制
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作者 余雪冰 《自然杂志》 北大核心 2007年第3期168-173,共6页
本文对生命史中多细胞物种的形成机制提出了创新性的观点并对此进行论述。该新观点认为:生命进化的本质是各种生命生存效率优化的过程。在此过程中,多细胞物种的产生必然要解决一对矛盾,即单细胞局部利益最大化与多细胞整体利益之间的... 本文对生命史中多细胞物种的形成机制提出了创新性的观点并对此进行论述。该新观点认为:生命进化的本质是各种生命生存效率优化的过程。在此过程中,多细胞物种的产生必然要解决一对矛盾,即单细胞局部利益最大化与多细胞整体利益之间的矛盾。解决这对矛盾是保证多细胞整体生存竞争效率的前提。因此,多细胞物种的进化必然是不断优化整体调控机制过程。调控机制的建立与完善是通过细胞的智能活动完成的。文章对多细胞物种的成种过程进行了逻辑推理,并依此推理过程提出了6个重要的预测,通过列举与这些预测相一致的事实证据来说明笔者该观点的合理性。 展开更多
关键词 进化 成种机制 效率最优化 调控机制 细胞智能性
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Genetic Polymorphism in GDF8 Region of HU Sheep Based on Microsatellite DNA 被引量:5
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作者 吴文忠 钱建共 +1 位作者 陈玲 孙伟 《Agricultural Science & Technology》 CAS 2009年第4期68-71,共4页
[ Objective ] This study was to analyze the genetic polymorphism in GDF8 Region of HU sheep. [Method] Four microsatellite loci including BMS1591, TEXAN-2, FCB128 and BM81124 mapped on GDF8 region of chromosome No. 2 o... [ Objective ] This study was to analyze the genetic polymorphism in GDF8 Region of HU sheep. [Method] Four microsatellite loci including BMS1591, TEXAN-2, FCB128 and BM81124 mapped on GDF8 region of chromosome No. 2 of sheep that may be correlated with growth performance were chosen to detect the molecular genetics foundation of growth performance of Hu sheep. [ Result] Four microsatellite loci detected were high in heterozygosity, more in effective alleles number and rich in polymorphic information, all the three indices passed through the high polymorphic level (PIC 〉0.5). [ Conclusion ] The four microsatellite loci detected could be used to estimate the genetic polymorphism of growth performance of Hu sheep. 展开更多
关键词 Hu sheep GDFS Microsatellite DNA Growth performance
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Mangrove Flora of the World 被引量:14
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作者 王伯荪 梁士楚 +1 位作者 张炜银 昝启杰 《Acta Botanica Sinica》 CSCD 2003年第6期644-653,共10页
The species composition and characteristics of mangrove flora in the world were reviewed and discussed. The results suggested that the world's mangrove plants have 84 species (including 12 varieties) in 24 genera ... The species composition and characteristics of mangrove flora in the world were reviewed and discussed. The results suggested that the world's mangrove plants have 84 species (including 12 varieties) in 24 genera and 16 families. Of which, true mangrove plants have 70 species (including 12 varieties) in 16 genera and 11 families, and semi-mangrove plants 14 species in eight genera and five families. The Eastern Group has 74 species (including 12 varieties) in 18 genera and 14 families, characterized by the genera Aegiceras, Osbornia, Aegialitis, Bruguiera, Ceriops, Kandelia, Scyphiphora and Nypa etc. The Western Group has only 10 species in six genera and five families, characterized by the endemic one-species family, Pelliceraceae, and the genus Laguncularia. The mangrove flora of China is composed of 26 species (including one variety) in 15 genera and 12 families, four of which are endemic. Hainan is most rich in mangrove species, making up about 96.2% of the Chinese total; Guangdong ranks second, making up about 42.3%. It has been demonstrated that Rhizophora stylosa was mistaken for R. mucronata in Taiwan by previous authors. 展开更多
关键词 MANGROVE FLORA floral composition Rhizophora mucronata
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A preliminary study on in-stream large woody debris in broadleaved and Korean pine forest in Changbai Mountain, Northeast China 被引量:2
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作者 邓红兵 王青春 王庆礼 《Journal of Forestry Research》 SCIE CAS CSCD 2002年第3期196-200,251,共5页
This study was conducted in Erdaobaihe River passing through the broadleaved and Korean pine forest located on the north slope of Changbai Mountain. In-stream large woody debris (LWD) in two segments of the river chan... This study was conducted in Erdaobaihe River passing through the broadleaved and Korean pine forest located on the north slope of Changbai Mountain. In-stream large woody debris (LWD) in two segments of the river channel was investigated with base diameter, top diameter, length, and decay class. To study relationship between in-stream LWD and adjacent riparian forest, species of each log of LWD in segment 1 was identified, and the riparian forest was examined by setting a 32m?4 m quadrat consisting of twelve 8m?m small quadrats. The results showed that, in segment 1, in-stream LWD loading was 1.733 m3/100m or 10.83 m3hm-2, and in segment 2, it was 1.709m3/100m or 21.36 m3hm-2. In-stream LWD in decay class III and IV were accounted for a high proportion, which was different from that in the broadleaved and Korean pine forest, and the possible reason might be different decomposing velocities due to different decomposing conditions. Logs of LWD in stream and living trees in riparian forest declined as diameter increased, and it was in a reverse J-shaped distribution except logs of LWD in segment 1 in the first diameter class. Volumes of LWD in stream and living trees in riparian forest increased as diameter increased, and it was in a typical J-shaped distribution. Loading and species component of in-stream LWD were correlative to status of riparian forest to a certain extent, and there also existed difference. Comparing the correlation and difference was helpful to study on dynamic of the riparian forest. 展开更多
关键词 In-stream large woody debris Broadleaved and Korean pine forest Changbai Mountain LOADING Riparian zone
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Seasonal variation in species composition and abundance of tintinnids in Shantou coastal water,China 被引量:2
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作者 刘华雪 黄良民 +2 位作者 谭烨辉 宋星宇 黄建荣 《Marine Science Bulletin》 CAS 2011年第1期80-86,共7页
Two cruises were conducted to study the composition and seasonal variation of tintinnids (Protozoa: Ciliata) in Shantou coast water dudng spring and fall. Remarkable seasonal variations in environmental parameters,... Two cruises were conducted to study the composition and seasonal variation of tintinnids (Protozoa: Ciliata) in Shantou coast water dudng spring and fall. Remarkable seasonal variations in environmental parameters, and tintinnids composition were observed. Tintinnids samples were enumerated and identified from 5 stations. 14 species belonging to 7 genuses of tintinnids were identified, and the dominate species was Leprotintinnus simple in these season. High tintinnids diversity and low abundance occurred in the fall, and on the contrary, low tintinnids diversity and high abundance occurred in the spring. No significant correlation occurred between tintinnids abundance and nutrients. Tintinnids abundance showed negative relationship with salinity (r2=0.63, P 〈 0.05), maybe this was due to the cold raised water carried sum nutrients rise to the surface water in the fall, rich nutrients and high phytoplankton biomass decrease the importance of tintinnids in the energy flow of aquatic food web. 展开更多
关键词 tinUnnids COMPOSITION DISTRIBUTION Shantou coast
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Distribution and composition of tintinnids ciliates in the northern South China Sea during summer 被引量:1
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作者 刘华雪 黄良民 +3 位作者 谭烨辉 宋星宇 黄建荣 李涛 《Marine Science Bulletin》 CAS 2010年第2期38-46,共9页
Tintinnids were enumerated and identified in samples collected from 36 stations between 18°-22°N, 107°-122 °E in the northern South China Sea (NSCS). 44 species belonging to 24 genera of tintinni... Tintinnids were enumerated and identified in samples collected from 36 stations between 18°-22°N, 107°-122 °E in the northern South China Sea (NSCS). 44 species belonging to 24 genera of tintinnids were recorded. The dominant species were He/icostome/la /onga and Tintinnopsis radix. Tintinnids abundance ranged from 0 to 2 200 cell/L, and mean abundance was 221cell/L in the surface water. Tintinnids abundance and species numbers decreased from coast to offshore. Upwelling and Pearl River discharge influenced the distribution of tintinnids by regulating nutrients supply. Maximum abundance (2 200 cell/L) was found in the surface water of A1. Tintinnids abundance showed positive relationship with chlorophyll a (Chl a) concentration, and no significant relationship was found between tintinnids abundance and temperature. 展开更多
关键词 TINTINNIDS COMPOSITION DISTRIBUTION northern South China Sea
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Polygynous Mating System and Behavioural Reason of Black Crested Gibbon (Nomascus concolor jingdongensis) at Dazhaizi,Mt.Wuliang, Yunnan,China 被引量:12
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作者 范朋飞 蒋学龙 +1 位作者 刘长铭 罗文寿 《Zoological Research》 CAS CSCD 北大核心 2006年第2期216-220,共5页
The field research on five black crested gibbon groups, recently performed at Dazhaizi, Mr. Wuliang, Central Yunnan, China, showed that all groups in the local population consisted of one adult male, two adult females... The field research on five black crested gibbon groups, recently performed at Dazhaizi, Mr. Wuliang, Central Yunnan, China, showed that all groups in the local population consisted of one adult male, two adult females and 2 - 5 sub-adults, juveniles and itfants. The mean group size was 6.2 in August 2003 and 6.4 in August 2005. Two subadult males disappeared from their natal home range and three newborns were given birth in Group 3 (G3) and G4 during this study. The two adult females in G1, G2 and G3 gave births and/or carried babies but at different times. There was no aggressive or dominating behaviour observed between the two adult females. One floating female was first seen in G3's territory on April 15, 2005. The two resident females interrupted her duet with adult male and chased her. We did not observe adult male chased this floating female and she left G3's territory 10 days later. Sub-adult males often kept distance with the family, and they often sang solo bouts in their natal territory before they dispersed. The sub-adult males and females dispersed from natal territory and two adult resident females rejected the third one, which might were the reasons why the black gibbon groups were polygyny in Dazhaizi. 展开更多
关键词 Nomascus concolor jingdongensis Group size and composition Social structure Polygyny Local population Wuliang Mountain
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Effects of Seed Rate on Root Twining Power and Seedling Quality of Machine-transplanted Super Rice 被引量:3
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作者 滕飞 朱德峰 +2 位作者 陈惠哲 蔡雪青 徐一成 《Agricultural Science & Technology》 CAS 2015年第12期2644-2648,2652,共6页
In order to investigate the effects of seed rate on root twining power and seedling quality of machine-transplanted super rice cultivars, Yongyou 12 and Zhongzheyou No.l, total 6 seed rates were arranged, and the grow... In order to investigate the effects of seed rate on root twining power and seedling quality of machine-transplanted super rice cultivars, Yongyou 12 and Zhongzheyou No.l, total 6 seed rates were arranged, and the growth characteris- tics, quality and root twining power of machine-transplanted rice seedlings were studied. The results showed that seed rate had great effects on root twining power and qualityof rice seedlings; with the increase of seed rate, the root twining power of rice seedlings was increased, but the quality of rice seedlings was significantly reduced; under the condition of high seed rate, rice seedlings were weak with less accumulate dry matter and nonuniform growth, and the proportion of weak seedlings was higher. When the seed rate of both rice cultivars was reduced by 10 g/tray, the average seedling height was increased by 0.5 cm, leaf age was increased by 0.1, stem base diameter was increased by 0.1 cm, and root number per plant was increased by 0.3. When the seed rate was increased by 10 g/tray, the accumulated dry matter per plant was reduced by 5.1 mg. With the increase of seed rate, the seedling quality of Zhongzheyou No.1 was decreased rapidly, and the proportion of weak seedlings was increased rapidly. However, Yongyou 12 has a larger elasticity in seed rate. When the seed rate reached to 50 g/tray, blanket seedlings of Yongy- ou 12 were nursed with uniform growth and higher quality, but the shoots were sparse with lower leaf area index. However, when the seed rate was up to 50 g/tray, blanket seedlings of Zhongzheyou No.1 were nursed with uniform growth and higher quality, as well as higher-density shoots. From a comprehensive point of view, the optimum seed rates of Yongyou 12 and Zhongzheyou No.1 were 65 and 50 g/tray, respectively. 展开更多
关键词 RICE Super rice Mechanical transplanting Seed rate Blanket seedling Seedling quality
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Study on the Biological Diversity of Nematode-trapping Fungi in Erhai Lake 被引量:4
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作者 杨晓燕 刘立盘 +3 位作者 苏锡钧 叶远邦 黄爱英 苏鸿雁 《Agricultural Science & Technology》 CAS 2011年第8期1100-1102,共3页
[Objective]The research aimed to investigate the biological diversity of nematode-trapping fungi in the sediment of Erhai Lake.[Method]616 pieces of sediments were collected from Erhai Lake.The traditional classificat... [Objective]The research aimed to investigate the biological diversity of nematode-trapping fungi in the sediment of Erhai Lake.[Method]616 pieces of sediments were collected from Erhai Lake.The traditional classification and identification methods were used to isolate,purify and identify.[Result]3 genera and 22 species of nematode-trapping fungi were isolated.Arthrobotrys oligospora,A.musiformis and Dactylella leptospora were the dominant species,and their detection rates were 28.05%,16.04% and 8.92% respectively.By analyzing the diversity of nematode-trapping fungi in four seasons,it was found that the biological diversity was richer in summer,spring and autumn,and the diversity indexes were 2.59,2.47 and 2.34 respectively.The diversity index in winter was 1.48 and was lower.Species forming the adhesive nets were predominant;positive rate was 41.00%.[Conclusion]The rich nematode-trapping fungi resource existed in Erhai Lake,and its biological diversity had the seasonal variation characteristic.The nematode-trapping fungi which formed the viscous net were the dominant species in Erhai Lake. 展开更多
关键词 Erhai Lake Nematode-trapping fungi Biological diversity
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Monitoring Report on Mosquitoes at Ports of Four Regions in East China during 2011—2014 被引量:1
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作者 吴薇 《Agricultural Science & Technology》 CAS 2017年第2期307-309,317,共4页
[Objective] The aim was to understand the species composition, distribution, density, seasonal fluctuation and pathogens of mosquitoes in four regions of East China to provide basic data for prevention and control of ... [Objective] The aim was to understand the species composition, distribution, density, seasonal fluctuation and pathogens of mosquitoes in four regions of East China to provide basic data for prevention and control of mosquitoes at ports. [Method] The mosquitoes at 21 ports of four regions in East China were investigated during 2011-2014 by CO2 lamp method, egg collection method, scoop method and visual method. The species of mosquitoes was identified, and pathogens in mosquitoes were detected. [Result] From 2011 to 2014, 102 583 mosquitoes were captured at the ports, belonging to 18 species, 6 genera and 1 family. Culex pipi- ens quinquefasciatus or Culex pipiens pallens was the dominant species at most ports. Mosquitoes could be captured from May to October, and the captured mosquitoes were the most in June. The positive rate of egg collectors was 9.41%, and the positive rate of breeding places was 7.23%. Rare entry mosquitoes were captured, and most of them were C. pipiens pallens. The detection results of dengue fever, malaria and other pathogens were negative. [Conclusion] C. pipiens quinquefasciatus or C. pipiens pallens was dominant at most ports, and the peak period was June. There were breeding environments of mosquitoes at some ports, so the prevention and control of mosquitoes at these ports should be paid more at- tention to in future. 展开更多
关键词 PORT MOSQUITO Species composition Seasonal fluctuation
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Present status and conservation strategies of mangrove resource in Guangdong, P. R. China 被引量:2
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作者 韩维栋 《Journal of Forestry Research》 SCIE CAS CSCD 2003年第2期151-154,共4页
According to the survey of Guangdong mangrove resource in 2001 and authors field investigations in the past 5 years, the total mature mangrove land area of Guangdong Province was estimated at 9084 hm2, accounting for ... According to the survey of Guangdong mangrove resource in 2001 and authors field investigations in the past 5 years, the total mature mangrove land area of Guangdong Province was estimated at 9084 hm2, accounting for 41.4% of total mangrove land area of China. These mangrove forests totally consisted of 50 species belonging to 28 families, distributed at more than 100 locations along the coastlines of Guangdong and most of them present a high dense and dwarf appearance. The Ass. Avicennia marina is the most dominant mangrove association. The investigation results showed that the mangrove forests with coverage rates above 0.7 accounted for 68.0% of the total mangrove land area of the province and 77.8% of mangrove forests was less than 2 m in tree height. Since 1950, 54.6% of mangrove forests have disappeared due to paddy rice reclaim, aquaculture and city constructions. Derivational conservation efforts are still weakly empowered and should be strengthened intensively. The author suggested that mangrove laws and regulations should be enforced, mangrove scientific research should be strengthened; and mangrove conservation awareness of local community should be raised on conservation of mangroves. 展开更多
关键词 GUANGDONG MANGROVE Present status of resource Conservation.
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Seed-induced synthesis of small-crystal TS-1 using ammonia as alkali source 被引量:11
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作者 薛腾 刘华萍 +3 位作者 王一萌 吴海虹 吴鹏 何鸣元 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2015年第11期1928-1935,共8页
Small-crystal TS-1 was synthesized via a seed-induced approach using ammonia as the alkali source and tetrapropylammonium bromide as an auxiliary structure-directing agent. The TS-1 samples were characterized using X-... Small-crystal TS-1 was synthesized via a seed-induced approach using ammonia as the alkali source and tetrapropylammonium bromide as an auxiliary structure-directing agent. The TS-1 samples were characterized using X-ray diffraction, N2 adsorption-desorption, Fourier-transform infrared spectroscopy, inductively coupled plasma atomic emission spectroscopy, scanning electron microscopy, and ultraviolet-visible spectroscopy. The use of the colloidal seed reduced the crystal size, and an appropriate amount of silicalite-1 seed assisted Ti incorporation into the TS-1 framework. This method reduces the cost of TS- 1 synthesis because a significantly smaller amount of tetrapropylammonium hydroxide is used. The catalytic performance of the synthesized small-crystal TS-1 samples in cyclohexanone ammoximation was better than that of bulk TS-1 as a result of improved diffusion and a larger number of active tetrahedral Ti centers. 展开更多
关键词 Small crystal TS- 1 molecular sieve Seed-induced synthesis Ammonia Catalytic oxidation Cyclohexanone ammoximation
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