检索结果-南通市图书馆

黄瓜连作土壤及营养基质热处理的生物效应研究

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

核农学报 2016年第6期30卷 1178-1185页

作者：武春成曹霞李天来河北科技师范学院园艺科技学院河北昌黎066600 沈阳农业大学园艺学院/省部共建教育部设施园艺重点实验室辽宁沈阳110866

为明确黄瓜连作土壤和营养基质热处理的生物效应,以连作12茬黄瓜的土壤和营养基质为试材,分别设55℃和75℃2个处理温度,48 h和96 h 2个处理时间,热处理后采用塑料钵进行黄瓜苗期试验,研究土壤和营养基质热处理对黄瓜生长、土壤酶活性、... 详细信息

为明确黄瓜连作土壤和营养基质热处理的生物效应,以连作12茬黄瓜的土壤和营养基质为试材,分别设55℃和75℃2个处理温度,48 h和96 h 2个处理时间,热处理后采用塑料钵进行黄瓜苗期试验,研究土壤和营养基质热处理对黄瓜生长、土壤酶活性、土壤微生物区系和土壤养分的影响。结果表明,连作土壤和营养基质热处理后均明显促进了黄瓜的生长,减轻了连作障碍的发生;热处理显著提高了土壤中的过氧化氢酶、中性磷酸酶和蔗糖酶活性及细菌和放线菌数量,以及有机质、全氮、碱解氮、速效钾的含量,降低了真菌数量;但短时间55℃热处理提高了营养基质过氧化氢酶、中性磷酸酶活性和细菌及放线菌数量,降低了蔗糖酶和脲酶活性、真菌数量及全氮、碱解氮、速效钾的含量。综上所述,对连作土壤和营养基质进行热处理可有效减轻黄瓜连作障碍,其中以55℃、96 h的处理效果最明显。本研究为蔬菜连作营养基质修复再利用提供了理论基础和技术依据。

关键词：热处理连作营养基质土壤黄瓜生物效应

Radio frequency interference detection based on the AC-UNet model

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2021年第5期21卷 168-178页

作者： Rui-Qing Yan Cong Dai Wei Liu Ji-xia Li Si-Ying Chen xian-Chuan Yu Shi-Fan Zuo Xue-Lei Chen College of Information Science and Technology Beijing Normal UniversityBeijing 100875China National Laboratory of Pattern Recognition Institute of AutomationChinese Academy of SciencesBeijing 100190China National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China

Radio frequency interference(RFI)is a serious issue in radio *** paper proposes a U-Net network model with atrous convolution to detect *** the ability of convolutional neural networks to extract image features of RFI,and learning RFI distribution patterns,the detection model of the RFI is *** use observational data containing real RFIs obtained by the tianlai telescope to train the model so that the model can detect *** the probability of a data point being RFI pixel by pixel,and set a *** the same time the dropout layer was added to avoid overfitting *** the predicted probability of a data point exceeds the threshold,it is considered that there is RFI,and if the predicted probability of a data point does not exceed the threshold,then it is considered that there is no RFI,so that the part of the image with RFI is *** results show that this approach can achieve satisfactory accuracy in the detection of radio observation images with a small amount of RFI.

关键词： methods:data analysis techniques:image processing methods:observational

The design and implementation of a ROACH2+GPU based correlator on the tianlai dish array

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2019年第7期19卷 133-142页

作者： Chen-Hui Niu Qun-Xiong Wang David MacMahon Feng-Quan Wu Xue-Lei Chen Ji-xia Li Hai-Jun Tian Guillaume Shippee Dan Werthimer xiao-Ping Zheng College of Physical Science and Technology Central China Normal UniversityWuhan 430079China Key Laboratory for Computational Astrophysics National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China University of California Berkeley Campbell Hall 339Berkeley CA 94720USA College of Science China Three Gorges UniversityYichang 443002China School of Astronomy and Space Sciences University of Chinese Academy of SciencesBeijing 100049China Center of High Energy Physics Peking UniversityBeijing 100871China

A digital correlator is a crucial element in a modern radio *** this paper,we describe a scalable design for the correlator system of the tianlai pathfinder array,which is an experiment dedicated to testing key technologies for conducting a 21cm intensity mapping *** correlator implements the FX design,which firstly performs a fast Fourier transform(FFT) including polyphase filter bank(PFB) computation using a Collaboration for Astronomy Signal Processing and Electronics Research(CASPER) Reconfigurable Open Architecture Computing Hardware-2(ROACH2) board,then computes cross-correlations by employing Graphics Processing Units(GPUs).The design has been tested both in laboratory and in actual observation.

关键词： instrumentation interferometers

Reflections and standing waves on the tianlai cylinder array

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2021年第3期21卷 73-85页

作者： Ji-xia Li Feng-Quan Wu Shi-Jie Sun Zi-Jie Yu Shi-Fan Zuo Ying-Feng Liu You-Gang Wang Cong Zhang Reza Ansari Peter Timbie Xuelei Chen National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China Center for Astrophysics and Department of Astronomy Tsinghua UniversityBeijing 100084China IJC Lab CNRS/IN2P3&Universite Paris-Saclay15 rue Georges Cl´emenceau91405 OrsayFrance´ Department of Physics University of Wisconsin Madison1150 University AveMadison WI 53703USA Center of High Energy Physics Peking UniversityBeijing 100871China

In 21 cm intensity mapping,the spectral smoothness of the foreground is exploited to separate it from the much weaker 21 cm ***,the non-smooth frequency response of the instrument complicates this *** and standing waves generate modulations on the frequency *** we report the analysis of the standing waves in the bandpass of the signal channels of the tianlai Cylinder *** Fourier transforming the bandpass into the delay time domain,we find various standing waves generated on the telescope.A standing wave with time delay at~142 ns is most clearly identified which is produced in the 15-meter feed *** also identify a strong peak at a shorter delay ofτ<50 ns,which may be a mix of the standing wave between the reflector and feed,and the standing wave on the 4 m intermediate frequency(IF)*** also show that a smoother frequency response could be partially recovered by removing the reflection-inducted ***,the standing wave on the antenna is direction-dependent,which poses a more difficult challenge for high precision calibration.

关键词： techniques:interferometric methods:data analysis

在线全文

学校读者我要写书评

暂无评论

日光温室太阳总辐射量变化规律及利用分析

中国农学通报 2012年第19期28卷 104-108页

作者：李霞罗新兰王蕊李天来须晖赵鑫勇沈阳农业大学/辽宁省设施园艺重点实验室沈阳110866

研究温室内太阳总辐射量、太阳辐射利用效率的变化规律,太阳总辐射和净辐射的关系以及新旧薄膜对其关系的影响,为日光温室环境控制提供理论依据。实时测定温室内太阳辐射量,与温室外太阳辐射进行比较分析,且对不同薄膜覆盖下的太阳辐射... 详细信息

研究温室内太阳总辐射量、太阳辐射利用效率的变化规律,太阳总辐射和净辐射的关系以及新旧薄膜对其关系的影响,为日光温室环境控制提供理论依据。实时测定温室内太阳辐射量,与温室外太阳辐射进行比较分析,且对不同薄膜覆盖下的太阳辐射环境进行对比。结果表明,9月-翌年4月,温室内月平均太阳总辐射量先减少后增加,12月只有4.45MJ/m2,4月为11.68MJ/m2;11月温室日总辐射利用效率最好,Q内/Q外值为75.99%,且Q外-Q内仅1.67MJ/m2。温室太阳总辐射与净辐射呈现较好的线性关系,3、4月份的线性方程表示为y=0.8277x-0.2909,相关系数R=0.995。旧膜A与新膜B相比,膜A的太阳辐射利用效率小于膜B,最多达13%,且使用膜A时,3、4月份总辐射与净辐射线性方程表示为y=0.9223x-0.1762,相关系数R=0.985。日光温室内太阳辐射环境变化规律及设施对其影响的研究是温室环境调控的基础。

关键词：日光温室番茄太阳总辐射量净辐射量光照时间薄膜