期刊文献+
共找到22,914篇文章
< 1 2 250 >
每页显示 20 50 100
In Search of Identity in Language and Irish Geography:On Seamus Heaney's Wintering. Out
1
作者 WU Kai-su 《Journal of Literature and Art Studies》 2017年第6期648-655,共8页
Seamus Heaney in his lifespan of 74 years is lauded not only for his great accomplishment in the field of poetry, butalso for his translation, editing and literary criticism. Yet, when it comes to socio-political affa... Seamus Heaney in his lifespan of 74 years is lauded not only for his great accomplishment in the field of poetry, butalso for his translation, editing and literary criticism. Yet, when it comes to socio-political affairs, the poet is not aunanimous favorite. Far from being an influential political activist sometimes anticipated by his friends andcountrymen in Ireland, Heaney resorted to his search for identities and for answers to his nation's predicament inthe world of words. As a poetic collection published during the political unrest in the seventies, Wintering Outdiscloses Heaney's composition of the dialectic between the aesthetic and the historical. In this essay, the authorwill look into Heaney's four poems in the collection, in which the poet's linguistic as well as geographical survey ofhis hometown is indispensible for readers who intend to discern his attitude in the critical period of his artisticformation。 展开更多
关键词 language geography identities Ireland wintering OUT
在线阅读 下载PDF
Importance of surrounding landscape features in explaining wintering waterbird diversity and community assembly in Jiangsu's inland lake wetlands
2
作者 Haoteng Zhang Lijun Xiao +2 位作者 Zixi Zhao Shenglai Yin Yong Zhang 《Avian Research》 2025年第4期626-636,共11页
As one of the important wintering areas along the East Asian-Australasian Flyway,wetlands in the Yangtze River floodplain face threats from land-use changes,yet its effects on wintering waterbirds at the landscape lev... As one of the important wintering areas along the East Asian-Australasian Flyway,wetlands in the Yangtze River floodplain face threats from land-use changes,yet its effects on wintering waterbirds at the landscape level remain understudied,impeding conservation practice.Here,using survey data collected across 14 inland lakes in Jiangsu Province in 2022,we calculated wintering waterbirds diversity(taxonomic,functional,phylogenetic)and assembly patterns(MPD/MNTD of functional and phylogenetic).Then,we interpreted satellite imagery of lake areas and buffer zones(5 km),and partitioned them into three land-use and landscape index categories(anthropogenic,ecological,and lake landscape).Finally,we employed multiple linear regression and hierarchical partitioning to explain the influence of landscape scales on wintering waterbird communities.Our results showed that the diversity and assembly of regional wintering waterbird communities tended to be consistent across taxonomic,functional,and phylogenetic dimensions.The standardized diversity indices indicated that functional assembly of communities tends to be clustered at both local and regional scale.In contrast,the phylogenetic structure showed a predominantly overdispersed pattern in most lakes at the local scale,while neutral processes dominated at the regional scale.Modeling showed that selected variables explained waterbird diversity and assembly well.Lake fragmentation increased species evenness but reduced other diversity indices,while landscape evenness was negatively associated with functional and phylogenetic assembly.Among anthropogenic factors,aquaculture ponds and impervious surfaces reduced all diversity dimensions,whereas cropland connectivity enhanced phylogenetic diversity.These factors had consistent effects on community assembly.For ecological variables,grassland area enhanced functional and phylogenetic diversity but led to more clustered functional assembly.Overall,maintaining the integrity and connectivity of lakes and their surrounding landscapes is essential for sustaining waterbird diversity and guiding wetland restoration. 展开更多
关键词 Community assembly CONSERVATION DIVERSITY Land use and land cover wintering waterbirds
在线阅读 下载PDF
融合图像和气象多源参数判定冬小麦发育期
3
作者 张佩 魏晓奕 +4 位作者 张继波 陈郑盟 苗茜 谢小萍 吴洪颜 《农业工程学报》 北大核心 2026年第1期122-131,共10页
为了实现小麦发育期的快速、无损、准确的智能判定,该研究提出了“多源参数融合-参数优选降维-概率模型判定”的思路方法,基于作物冠层RGB颜色偏态分布参数和气象因子,探索了基于融合参数的贝叶斯分类算法在小麦发育期判定上的应用。在... 为了实现小麦发育期的快速、无损、准确的智能判定,该研究提出了“多源参数融合-参数优选降维-概率模型判定”的思路方法,基于作物冠层RGB颜色偏态分布参数和气象因子,探索了基于融合参数的贝叶斯分类算法在小麦发育期判定上的应用。在山东省菏泽、泰安和桓台设置观测站点,连续4 a获取冬小麦冠层高清图像及气象数据。相关性分析表明,20个冠层颜色偏态参数与4个光热累积指标均与小麦发育期显著相关。以人工观测的生育期作为先验知识,分别建立了基于冠层颜色、气象因子及二者融合的判定模型,并比较不同模型的判定效果。结果表明,以相关分析结果作为依据重新选定贝叶斯判定模型的最优输入参数组合是红通道偏度、绿通道峰度、总积温、累积光合有效辐射,优化参数后的判定模型在建模样本中的判定准确率超过90%,对跨年度和跨生态区样本亦具有良好的适用性与稳健性。该研究将冠层图像信息与气象因子相结合,借助数字图像处理与机器学习方法,有效提升了冬小麦发育期判定的精度,为作物生产的精准管理与农业智能化提供了技术支撑。 展开更多
关键词 图像 冠层 颜色 气象参数 光热 发育期 冬小麦
在线阅读 下载PDF
我国冬小麦干旱灾害研究进展
4
作者 霍治国 王懿 +5 位作者 李美萱 米前川 张丰寅 孔瑞 杨建莹 霍雨欣 《应用气象学报》 北大核心 2026年第1期1-15,共15页
干旱灾害是中国农业生产面临的首要自然灾害,明确冬小麦干旱灾害的研究现状,对把握今后的研究方向具有重要价值。文章通过文献分析方法,从干旱的定义类型、灾害影响、成灾机理、量化表征、时空演变规律、监测预警、防灾减灾等方面全面... 干旱灾害是中国农业生产面临的首要自然灾害,明确冬小麦干旱灾害的研究现状,对把握今后的研究方向具有重要价值。文章通过文献分析方法,从干旱的定义类型、灾害影响、成灾机理、量化表征、时空演变规律、监测预警、防灾减灾等方面全面梳理现有研究成果,并展望未来研究趋势。基于灾害发生时段,冬小麦干旱主要分为秋冬旱和春旱,其中抽穗期干旱对冬小麦产量影响最大;我国所有冬麦区均有干旱灾害发生,其中黄淮海冬麦区干旱程度最严重;冬小麦干旱常用气象干旱指数和农业干旱指数表征;当前冬小麦干旱监测正从地-天二维向地-空-天三维立体监测转变;冬小麦干旱预警预测主要通过数值预报信息与干旱指数、农业气象模型结合实现。深入探究作物对干旱的响应机理、构建针对冬小麦抗旱动态性的干旱识别指数、加强干旱灾害监测预警技术的创新研发,提升监测精度与预测准确性是今后研究重点。 展开更多
关键词 冬小麦 干旱灾害 灾害指数 时空分布 监测预测
在线阅读 下载PDF
中国春节假期旅游气候空间格局及变化
5
作者 赵珊珊 高歌 李莹 《气象》 北大核心 2026年第1期94-104,共11页
中国春节假期一般在1月20日至2月26日之间,春节假期形成的大规模旅游客流呈现出以气候因素为主导的驱动模式。文章采用人体舒适度指数和趋势分析等方法,揭示了春节假期中国旅游气候的时空分布特征,并进一步分析了变化趋势。结果表明:199... 中国春节假期一般在1月20日至2月26日之间,春节假期形成的大规模旅游客流呈现出以气候因素为主导的驱动模式。文章采用人体舒适度指数和趋势分析等方法,揭示了春节假期中国旅游气候的时空分布特征,并进一步分析了变化趋势。结果表明:1991-2020年春节假期,中国气候特征呈显著的南北差异,长江以南大部分地区平均气温在5℃以上,而黑龙江大部、内蒙古东北部在-15℃以下;降水主要集中在江南和华南中东部。春节假期华南大部及云南大部、四川南部人体舒适日数在10 d以上,有利于避寒旅游;东北大部、内蒙古中部和东北部、新疆北部积雪日数达15 d以上,有利于冰雪旅游。降水和雾为南方避寒旅游主要不利影响天气,而大风和寒冷天气则不利于北方冰雪旅游。1961年以来,春节假期华南东部、云南大部、四川南部等地人体舒适日数显著增多,同时降水日数减少,有利于避寒旅游;北方地区大风和寒冷日数减少明显,有利于冰雪旅游。总的来看,春节假期南方避寒和北方冰雪旅游气候条件整体呈趋好态势,这对于推动各地开展特色旅游服务和实现气候资源向旅游经济高效转化具有重要参考意义。 展开更多
关键词 春节假期 人体舒适度指数 避寒旅游 冰雪旅游 气候变化
在线阅读 下载PDF
Seasonal dynamics of wintering waterbirds in two shallow lakes along Yangtze River in Anhui Province 被引量:15
6
作者 陈锦云 周立志 +3 位作者 周波 许仁鑫 朱文中 徐文彬 《Zoological Research》 CAS CSCD 北大核心 2011年第5期540-548,共9页
The shallow lake wetlands in the middle and lower Yangtze River floodplain are important wintering and stopover habitats for migratory waterbirds on the East Asia-Australia Flyway.With increasing fishery practices in ... The shallow lake wetlands in the middle and lower Yangtze River floodplain are important wintering and stopover habitats for migratory waterbirds on the East Asia-Australia Flyway.With increasing fishery practices in recent years,however,the wetlands have deteriorated significantly and now threaten wintering waterbirds.To gain insight into the influence of deteriorating wetlands on waterbirds,we conducted a survey of wintering waterbird species,population size,and distribution across 11 belt transects in Caizi Lake and Shengjin Lake,two shallow lakes along the Yangtze River in Anhui Province from November 2007-April 2008 and from November 2008-April 2009,respectively.The impacts of different fishery patterns on the distribution of waterbirds were also analyzed.A total of 43 waterbirds species belong to 7 orders of 12 families were counted during the surveys,of which 38 were found in Caizi Lake with a density of 8.2 ind./hm2,and 42 in Shengjin Lake with a density of 3.5 ind./hm2.Geese(Anser cygnoides),bean geese(Anser fabalis),tundra swan(Cygnus columbianus),and dunlin(Calidris alpina) were the dominant species in the two shallow lakes.Species number and individual assemble reached maximum at the end of December and in early January of the following year,without coincidence of the largest flock for different ecological groups.Based on waterbird diversity across the 11 belt transects and the fishery patterns,habitats could be divided into three groups.Gruiformes,Anseriformes and Charadriiformes had relatively higher densities in the natural fishery zones and lower densities in the cage fishery zones;whereas,the density of Ardeidae showed little change across all lake zones.It is important to develop sustainable fishery patterns in shallow lakes along the middle and lower Yangtze River floodplain to better protect resources of wintering waterbirds. 展开更多
关键词 wintering waterbirds Community diversity Seasonal dynamic Fishery disturbance Caizi Lake Shengjin Lake
在线阅读 下载PDF
Habitat utilization and resource partitioning of wintering Hooded Cranes and three goose species at Shengjin Lake 被引量:11
7
作者 赵凤婷 周立志 徐文彬 《Chinese Birds》 CSCD 2013年第4期281-290,共10页
The loss and degradation of wetlands have adversely affected waterbirds, which depend on wetland habitats. Interspecific competition has an important effect on habitat utilization of wintering waterbirds. Resource uti... The loss and degradation of wetlands have adversely affected waterbirds, which depend on wetland habitats. Interspecific competition has an important effect on habitat utilization of wintering waterbirds. Resource utilization, including partitioning, in degraded wetlands has become a hot issue in ecological studies of wintering waterbirds. In order to have an insight into the habitat utilization and resource partitioning between a Hooded Crane(Grus monacha) population and the guild of three goose species, i.e., Anser fabalis, A. albifrons and A. erythropus wintering in lake wetlands, we carried out a study at Shengjin Lake National Nature Reserve from November 2011 to April 2012. We surveyed the Hooded Cranes and goose guild foraging in various habitats during the wintering periods with a combined method of fixed route searching and fixed site observations. Resource partitioning was studied by means of calculating habitat utilization rates and the width and overlap of spatial niches. The results showed that the habitat utilization rate and the width of spatial niches of the Hooded Crane population and goose guild shifted with the season. The habitat utilization rates of the cranes in grasslands were high at all three wintering stages. The habitat utilization rates were 0.454, 0.435 and 0.959 respectively for the Hooded Cranes and 0.627, 0.491 and 0.616 for the goose guild. This suggests that the overlap in grasslands was higher between cranes and goose guild. Most habitats were accessible at the middle stage, so the width of the spatial niche of the cranes(1.099) and goose guild(1.133) both reached their peak at this stage. The greatest niche overlap was 0.914 for these two groups at the late stage, followed by 0.906 at the middle stage and the smallest was 0.854 at the early stage. Ecological response to the changes in habitats of wintering waterbirds was clearly shown in the dynamic variations of the niche of both the Hooded Cranes and the three goose species. Coexistence among waterbirds was achieved by regulation of niche width to reduce niche overlap and relieve interspecific resource partitioning. 展开更多
关键词 habitat utilization NICHE wintering ecology Hooded Crane(Grus monacha) goose guild
原文传递
Wintering ecology of the Black Stork (Ciconia nigra) in Beijing 被引量:2
8
作者 李晓京 史洋 +1 位作者 徐基良 鲍伟东 《Chinese Birds》 2011年第1期46-52,共7页
The Black Stork (Ciconia nigra) is a new winter resident in Beijing due to temperature changes.To understand the wintering ecology of this species better, a field survey covering the number of birds of this population... The Black Stork (Ciconia nigra) is a new winter resident in Beijing due to temperature changes.To understand the wintering ecology of this species better, a field survey covering the number of birds of this population, habitat selection, feeding activity and grouping behavior was conducted at the Shidu Nature Reserve from January 2004 to March 2009. The results show that the Black Stork selected the Juma River at this nature reserve as their new winter habitat. The number of birds in this population decreased from 28 in the 2004/2005 winter to 17 in the 2007/2008 winter with a subsequent recovery to 23 the following year. The wintering flock was formed in mid-November and dispersed in mid-March, but the date changed with seasonal temperature fluctuations. The storks exhibited feeding habitat fidelity and the main food type was fish (> 92.4%). There was no significant variation in food composition between adults and sub-adults (Mann-Whitney U test, U = 1.00, p = 0.44). Feeding activity occurred in the morning and at noon during early winter, but concentrated in the afternoon during mid winter, divided into dawn and dusk in late winter. Daily fish intake was 538 g for adults and 449 g for sub-adults if the period of foraging reached six hours in the wild, which was similar to the level under artificial feeding. Agonistic behavior among feeding birds was observed among group members in late winter. The main negative factor for wintering Black Stork was a reduced feeding habitat resulting from increased water depth due to damming of the river to benefit tourism and to wetland exploitation. 展开更多
关键词 BEIJING Ciconia nigra foraging behavior wintering ecology
原文传递
Effects of applying manure on soil physical properties and crop yield under long-term saline water irrigation
9
作者 Khadija SHAHID LIU Zimeng +3 位作者 SHAO Liwei NIU Junfang CHEN Suying ZHANG Xiying 《中国生态农业学报(中英文)》 北大核心 2026年第1期103-117,共15页
To maintain soil quality under long-term saline water irrigation,the influence of manure on soil physical properties was examined.Long-term saline irrigation has been conducted from 2015 to 2024 at the Nanpi Eco-Agric... To maintain soil quality under long-term saline water irrigation,the influence of manure on soil physical properties was examined.Long-term saline irrigation has been conducted from 2015 to 2024 at the Nanpi Eco-Agricultural Experimental Station of Chinese Academy Sciences in the Low Plain of the North China Plain,comprising four irrigation treatments:irrigation once at the jointing stage for winter wheat with irrigation water containing salt at fresh water,3,4 and 5 g·L^(–1),and maize irrigation at sowing using fresh water.Manure application was conducted under all irrigation treatments,with treatments without manure application used as controls.The results showed that under long-term irrigation with saline water,the application of manure increased the soil organic matter content,exchangeable potassium,available phosphorus,and total nitrogen content in the 0–20 cm soil layer by 46.8%,117.0%,75.7%,and 45.5%,respectively,compared to treatments without manure application.The application of manure reduced soil bulk density.It also increased the proportion of water-stable aggregates and the abundance of bacteria,fungi,and actinomycetes in the tillage soil layer compared to the controls.Because of the salt contained in the manure,the application of manure had dual effects on soil salt content.During the winter wheat season,manure application increased soil salt content.The salt content was significantly reduced during the summer maize season,owing to the strong salt-leaching effects under manure application,resulting in a smaller difference in salt content between the manure and non-manure treatments.During the summer rainfall season,improvements in soil structure under manure application increased the soil desalination rate for the 1 m top soil layer.The desalination rate for 0–40 cm and 40–100 cm was averagely by 39.1%and 18.9%higher,respectively,under manure application as compared with that under the nomanure treatments.The yield of winter wheat under manure application was 0.12%lower than that of the control,owing to the higher salt content during the winter wheat season.In contrast,the yield of summer maize improved by 3.9%under manure application,owing to the increased soil nutrient content and effective salt leaching.The results of this study indicated that manure application helped maintain the soil physical structure,which is important for the long-term use of saline water.In practice,using manure with a low salt content is suggested to reduce the adverse effects of saline water irrigation on soil properties and achieve sustainable saline water use. 展开更多
关键词 saline water irrigation soil physical properties winter wheat-summer maize double-cropping system soil salinity MANURE
在线阅读 下载PDF
IN THE SPOTLIGHT
10
《Women of China》 2026年第1期10-12,共3页
Chinese State Councilor Urges Athletes to Strive for Glory at Milan-Cortina Winter Olympics Chinese State Councilor Shen Yiqin called on China's winter Olympic athletes to be better prepared for the Milan-Cortina ... Chinese State Councilor Urges Athletes to Strive for Glory at Milan-Cortina Winter Olympics Chinese State Councilor Shen Yiqin called on China's winter Olympic athletes to be better prepared for the Milan-Cortina 2026 Games and strive for glory for their nation.Shen made the remarks on December 24,2025,while meeting with athletes and coaches in their training base in Beijing. 展开更多
关键词 Athletes Training Milan Cortina Chinese State Councilor GLORY Winter Olympics Shen Yiqin
原文传递
THIS WEEK
11
《Beijing Review》 2026年第3期3-11,共9页
HARVESTING WINTER’S BOUNTY.Horses gallop as part of a performance at a wetland park in Zhaosu County,Xinjiang Uygur Autonomous Region,on January 3,showcasing the area’s new winter vision.The county is now leveraging... HARVESTING WINTER’S BOUNTY.Horses gallop as part of a performance at a wetland park in Zhaosu County,Xinjiang Uygur Autonomous Region,on January 3,showcasing the area’s new winter vision.The county is now leveraging its unique ice and snow resources to develop diverse tourist services and attract visitors. 展开更多
关键词 HARVESTING develop diverse tourist services wetland park WINTER ice snow resources performance WETLAND PARK
原文传递
新疆冬小麦淀粉组分对淀粉糊化特性及蛋白品质的影响
12
作者 张欣 刘鹏鹏 +4 位作者 聂迎彬 孔德真 李江博 桑伟 李卫华 《西北农业学报》 北大核心 2026年第1期15-22,共8页
为了给新疆小麦淀粉品质改良提供理论依据,选用170个新疆本地和国内外引进冬小麦品种,研究其淀粉组分、淀粉糊化特性及其与蛋白品质的关系。结果表明,新疆冬小麦淀粉组分含量和糊化特性参数值较低,破损淀粉含量较高,其中破损淀粉、支链... 为了给新疆小麦淀粉品质改良提供理论依据,选用170个新疆本地和国内外引进冬小麦品种,研究其淀粉组分、淀粉糊化特性及其与蛋白品质的关系。结果表明,新疆冬小麦淀粉组分含量和糊化特性参数值较低,破损淀粉含量较高,其中破损淀粉、支链淀粉、峰值粘度、稀懈值等变异系数较高,变异范围为10.19%~30.05%,是新疆冬小麦淀粉特性改良的重点。参试材料中筛选出低破损淀粉、高峰值粘度的材料4份,‘郑366’‘矮抗58’‘冷麦8号’和‘Sunstate’。相关性研究表明,直链淀粉含量与峰值粘度(r=-0.37)、稀懈值(r=-0.32)之间极显著负相关;破损淀粉与最终粘度(r=0.16)、回升值(r=0.21)和峰值时间(r=0.39)呈显著或极显著正相关,与稀懈值(r=-0.24)呈极显著负相关。直链淀粉含量与籽粒蛋白含量(r=-0.20)、面粉蛋白含量(r=-0.19)及干面筋含量(r=-0.16),支链淀粉含量与干面筋含量(r=-0.16)及湿面筋含量(r=-0.19),总淀粉含量与湿面筋含量(r=-0.19),破损淀粉与籽粒蛋白含量(r=-0.23),湿面筋含量与回升值(r=-0.17)等指标均呈显著或极显著负相关;淀粉糊化特性与其余蛋白品质性状之间未达显著相关水平,淀粉组分主要对蛋白品质呈负向作用。 展开更多
关键词 新疆冬小麦 淀粉组分 淀粉糊化特性 蛋白品质
在线阅读 下载PDF
FOCUS
13
《China Today》 2026年第1期6-15,共10页
PHOTO NEWS Unforgettable Winter Break Tourists take selfies in front of snow sculptures in the Fenghuang Mountain Scenic Area,Yakeshi City in Inner Mongolia Autonomous Region,on December 7,2025.
关键词 winter break selfies fenghuang mountain scenic area yakeshi city inner mongolia autonomous region TOURISTS snow sculptures december
在线阅读 下载PDF
Winter Tourism on Fast Track--How the Changbai Mountains scenic area redefines the visitor experience through service and story
14
作者 Ji Jing 《Beijing Review》 2026年第3期36-37,共2页
The Cloud Top Heavenly Palace,a majestic palace complex built with snow in the Changbai Mountains scenic area in Jilin Province,was officially illuminated and opened to the public on December 26,2025.This impressive i... The Cloud Top Heavenly Palace,a majestic palace complex built with snow in the Changbai Mountains scenic area in Jilin Province,was officially illuminated and opened to the public on December 26,2025.This impressive installation,with a main building measuring 20 meters high and 60 meters wide,faithfully recreates a classic scene from the best-selling Grave Robbers'Chronicles web novel series by Xu Lei,better known by his pseudonym Nanpai Sanshu. 展开更多
关键词 STORY snow installation Grave Robbers Chronicles nanpai sanshu winter tourism Changbai Mountains Scenic Area Cloud Top Heavenly Palace SERVICE
原文传递
Slippery Saga
15
作者 Sam Duckett 《China Weekly》 2026年第2期62-62,共1页
With the brisk winter season just around the corner,my now 5-year-old's birthday was approaching,and I had a big celebration planned full of presents,cake and a fun day out.However,this year,she had a request of h... With the brisk winter season just around the corner,my now 5-year-old's birthday was approaching,and I had a big celebration planned full of presents,cake and a fun day out.However,this year,she had a request of her own.One frosty evening,she glided up to me and said,"Dad,this year for my birthday,I want to learn how to be a figure skater." 展开更多
关键词 birthday celebration figure skating winter season
原文传递
冬小麦田间温湿度特征及其模拟模型构建
16
作者 马美娟 陈永清 +1 位作者 胡莉婷 余卫东 《中国农业气象》 2026年第1期119-132,共14页
为研究冬小麦田间温湿度变化及其与临近气象观测站温湿度的定量关系,2022年10月−2023年5月在商丘农业气象观测站冬小麦试验田10cm、30cm、50cm、70cm、150cm高度处安装温湿度记录仪,研究不同生长阶段和不同天气类型冬小麦田间温湿度时... 为研究冬小麦田间温湿度变化及其与临近气象观测站温湿度的定量关系,2022年10月−2023年5月在商丘农业气象观测站冬小麦试验田10cm、30cm、50cm、70cm、150cm高度处安装温湿度记录仪,研究不同生长阶段和不同天气类型冬小麦田间温湿度时空特征。采用线性回归方法,分别建立冬小麦全生育期和不同天气类型下田间温湿度与百叶箱温湿度的关系模型,并进行检验,以期为冬小麦气象服务提供数据支撑,提高农业气象服务水平。结果表明:(1)冬小麦分蘖−越冬期、返青−抽穗期、开花−成熟期田间各高度气温与百叶箱气温日变化特征一致,且3个生长阶段田间各高度气温7:00−16:00均高于百叶箱气温0.1~4.1℃,其余时段均低于百叶箱气温0.1~3.7℃。3个生长阶段田间各高度日最高气温出现时间较百叶箱温度偏早1~2h,最低气温较百叶箱偏早0~1h。(2)除冬小麦开花−成熟期50−150cm处上午某些时刻田间空气相对湿度低于百叶箱0.1~3.7个百分点,其他生长阶段、高度和时次均高于百叶箱0.6~26.8个百分点。3个生长阶段百叶箱空气相对湿度最小值出现时间比田间晚1~2h。(3)田间和百叶箱温湿度的日变化幅度大小依次为晴天>多云>阴天。晴天百叶箱与田间10−150cm气温差的平均值分别较多云和阴天高0.4℃和0.5℃,晴天百叶箱与田间10−150cm空气相对湿度差平均值分别较多云和阴天高1.8个和2.1个百分点。(4)全生育期和不同天气类型不同时间尺度田间各高度温湿度模拟模型均通过了0.01水平的显著性检验,且日尺度模拟效果优于小时尺度模型,气温模拟效果优于空气相对湿度,所有模型的模拟精度随田间监测高度增加逐渐升高。不同天气类型下,田间各高度温湿度模拟效果阴天>多云>晴天。 展开更多
关键词 冬小麦 田间 百叶箱 观测站 时间尺度
在线阅读 下载PDF
基于改进YOLOv8模型的冬小麦穗识别技术
17
作者 宫志宏 闫锦涛 +3 位作者 于红 刘涛 刘布春 李树岩 《中国农业气象》 2026年第1期133-142,共10页
针对大田环境中麦穗目标较小、分布稠密及重叠遮挡等问题,以无人机拍摄冬小麦为研究对象,基于YOLOv8模型提出一种改进的冬小麦穗检测方法,在Neck(颈部网络)增加SimAM注意力机制,融合GhostNetV2模块至Neck的C2f模块中,在增强空间和通道... 针对大田环境中麦穗目标较小、分布稠密及重叠遮挡等问题,以无人机拍摄冬小麦为研究对象,基于YOLOv8模型提出一种改进的冬小麦穗检测方法,在Neck(颈部网络)增加SimAM注意力机制,融合GhostNetV2模块至Neck的C2f模块中,在增强空间和通道特征表达能力、保证特征融合效率的基础上实现了模型轻量化,使得检测网络更适应复杂的大田环境下麦穗检测,同时,设置输入图像分辨率为1280px×1280px,最大限度地保留麦穗图像中关键特征信息。结果表明:改进后的YOLOv8模型平均精度和F1分数分别为93.1%和90.5%,权重文件仅占18.3MB,参数量9.4M,平均精度和F1分数较标准YOLOv8提高0.5个和0.8个百分点,权重文件大小和参数量分别降低3.3MB和1.7M,模型更加轻量化,整体性能优于原始YOLOv8模型,实现了复杂环境下小目标、高重叠度的麦穗数量检测。 展开更多
关键词 麦穗 YOLOv8 模型轻量化 目标检测 注意力机制
在线阅读 下载PDF
基于转录组学分析白菜型冬油菜BraIAA基因家族
18
作者 宫辉 武军艳 +5 位作者 刘丽君 马骊 张露露 任思韬 马愿强 潘巧文 《核农学报》 北大核心 2026年第2期255-267,共13页
生长素/吲哚乙酸(Aux/IAA)家族是一类早期生长素反应基因家族,在植物的生长发育过程中,发挥抵御低温胁迫的重要作用。为探究BraIAA基因在白菜型冬油菜中的系统发育和表达模式,对BraIAA基因家族进行全基因组鉴定和表达分析,包括基因结构... 生长素/吲哚乙酸(Aux/IAA)家族是一类早期生长素反应基因家族,在植物的生长发育过程中,发挥抵御低温胁迫的重要作用。为探究BraIAA基因在白菜型冬油菜中的系统发育和表达模式,对BraIAA基因家族进行全基因组鉴定和表达分析,包括基因结构、进化关系、染色体分布、保守结构域和理化性质,同时采用不同时长的低温处理,应用荧光定量技术分析不同基因在不同品种中的表达特性。结果表明,在白菜型冬油菜基因组中鉴定到62个IAA基因家族成员(BraIAA),系统发育树将其分为5个亚家族,家族成员在10条染色体上呈不均匀分布。保守结构域分析结果显示,基因长度较短,且不含内含子;共线性分析发现,BraIAA基因家族在拟南芥的5条染色体上都存在共线性关系,且顺式作用元件分布多样,亚细胞预测发现,大部分基因定位在细胞核,少数定位在内质网和质膜。实时荧光定量PCR(qRT-PCR)结果显示,低温处理后,Bra032521.1和Bra030419.1基因在两个品种叶片中的表达量均显著升高,Bra040122.1基因在两个品种中的表达先升高后降低;Bra011082.1、Bra030219.1和Bra040398.1基因在处理后表达量均降低,而Bra022164.1和Bra005508.1基因在两个品种中的表达模式相反。由此推断,Bra032521.1和Bra030419.1基因在白菜型冬油菜的低温胁迫响应中发挥正调控作用。本研究为探索白菜型冬油菜在低温处理后BraIAA基因家族的功能和调控机制提供了参考。 展开更多
关键词 BraIAA基因家族 白菜型冬油菜 低温处理 表达模式
在线阅读 下载PDF
面向探地雷达的冬笋智能识别与参数估计方法
19
作者 汤延杰 杨为泽 +4 位作者 黄俊达 张婷婷 黄栋 胡启昌 孔祥增 《农机化研究》 北大核心 2026年第4期136-147,共12页
为解决探地雷达场景下冬笋检测图像背景复杂、关键目标解释困难、自动化程度不足且检测精度有限等问题,提出了一种多层融合处理的B-Scan图像自动化定位提取方案。通过开展多次冬笋场地预填埋试验采集了一批高可用数据,数据集涵盖了不同... 为解决探地雷达场景下冬笋检测图像背景复杂、关键目标解释困难、自动化程度不足且检测精度有限等问题,提出了一种多层融合处理的B-Scan图像自动化定位提取方案。通过开展多次冬笋场地预填埋试验采集了一批高可用数据,数据集涵盖了不同尺寸和位置的雷达图像,为算法的训练和预测提供了丰富的数据支撑。①替换层次更深、提取能力更强的ResNet50替换vgg16主干网络,在提高网络性能的同时兼备更强的目标语义位置信息抽象能力;②为了更好地捕获目标检测任务中的多尺度信息,增强其对小目标的检测能力,引入具备inception并行结构、空洞卷积的D-FEM特征增强模块和RFB-E模块来扩展感受野,有效增强浅层特征并保留了更多的位置边缘纹理信息;③提出了一种上下文交叉的语义特征融合模块,融合浅层细节和深层语义特征的同时兼备上下文信息;④设计了一种针对探地雷达图像数据规律的Otsu累积色差改进算法,有效解决了ROI感兴趣区域内传统分割算法双曲线提取不佳的问题;⑤对CTFP算法拟合后的双曲线进行SG滤波操作,还原笋茎和填埋深度信息。试验结果表明:相较于SSD原检测网络模型,FFR-SSD的均值平均精度由91.23%增至96.06%,提升了4.83个百分点;累积色差改进的OTSU算法也优于直方图加权法、多阈值OTSU法和其它OTSU改进的阈值偏向算法;笋茎参数预测的总相对平均误差为8.24%,深度预测误差为8.90%。本文算法在处理复杂雷达图像和参数获取方面具备一定的推理优势,可为冬笋智能识别和参数预测技术的推广应用奠定坚实的技术基础。 展开更多
关键词 冬笋 智能识别 探地雷达 SSD 特征融合 图像分割
在线阅读 下载PDF
基于大田试验的冬小麦气象服务效益定量评估初探
20
作者 郭康军 姬兴杰 董宛麟 《中国农业气象》 2026年第1期7-19,F0002,共14页
2023年10月在河南省新乡市高标准农田设置完全响应区、部分响应区和不响应区,并在部分响应区随机布设仅不开展赤霉病防控和仅不开展干热风防控两种处理,共5个试验处理。试验期间按照2期河南省农业气象灾害预警信息(干热风、赤霉病)和2... 2023年10月在河南省新乡市高标准农田设置完全响应区、部分响应区和不响应区,并在部分响应区随机布设仅不开展赤霉病防控和仅不开展干热风防控两种处理,共5个试验处理。试验期间按照2期河南省农业气象灾害预警信息(干热风、赤霉病)和2期河南省农业气象服务周报建议,于试验点开展2次灌溉(返青期、拔节期)、赤霉病防控(抽穗期)和干热风防控(灌浆期)处理,并结合其他调查及观测结果,定量分析农业气象服务信息不同响应处理对冬小麦主要生长要素及经济效益的影响。结果表明:(1)及时响应(1~14d)冬小麦赤霉病和干热风灾害预警信息,并进行相关防控,可有效减轻危害,部分响应区赤霉病防控地块冬小麦赤霉病病穗率降低1.50个百分点,部分响应区干热风防控地块千粒重提高1.42g,灌浆速率提高0.12g·d^(−1)。(2)冬小麦抽穗期和灌浆期不同响应处理下,主要生长要素差异显著。完全响应处理下抽穗期平均穗、茎和叶干重分别为2.73g、6.57g和2.74g,整体高于部分响应处理;灌浆期平均穗、叶干重和穗粒数分别为21.34g、2.15g和41.93个,整体呈完全响应处理>部分响应处理>不响应处理的趋势。(3)对农业气象服务信息及时响应,可显著增产增收。完全响应处理较部分响应处理每公顷冬小麦可增产666.67kg,增收1690.00元,较不响应处理每公顷增产2310.81kg,增收4435.95元;部分响应处理较不响应处理每公顷可增产1644.14kg,增收2745.95.元。通过对农业气象服务信息不同响应处理产生的效益进行定量评估,对提升冬小麦单产具有重要科技支撑和生产指导意义。 展开更多
关键词 河南 冬小麦 气象服务效益 高标准农田
在线阅读 下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部