水稻乳苗抛栽与其它栽培方式干物质生产特性的比较研究   总被引：4，自引：0，他引：4  

马殿荣  陈温福  苏英山  李磊鑫  高峰 《辽宁农业科学》2004,(5):6-9

对水稻乳苗抛栽和手插秧、抛秧、水直播的干物积累与分配进行了分析。结果表明，不同群体经济产量与总干物质积累量、抽穗期至灌浆期的干物质积累速度之间的正相关达极显著水平，与抽穗前干物质积累量的正相关未达显著水平，与抽穗后的干物质积累量呈极显著正相关。水稻乳苗抛栽干物质积累速度低，抽穗灌浆期至成熟期绿叶和茎鞘干重比例较高，抽穗后干物质积累量低。  相似文献   

磷钨酸银纳米粒子光散射法测定多巴胺     

王俊  梁文婷  樊小林  黄承志 《西南大学学报》2013,35(5)

在醋酸-醋酸钠缓冲溶液pH=5.0的条件下,多酸纳米粒子Ag3PW12O40可以与多巴胺相互作用.以光散射信号为表征手段,可以得出在多巴胺浓度为3.0×10 8～1.2×10-5 mol/L的范围内光散射信号随着多巴胺浓度的增加呈线性增强,检出限(3σ)为1.4×10-8 mol/L.这种多巴胺的光散射测定方法被成功应用于盐酸多巴胺注射液的测定.  相似文献   

农田水样中微囊藻毒素-LR拉曼检测方法的研究     

黄珊  孟辉  曾昆  黄哲 《农业环境科学学报》2020,39(8):1862-1868

本研究建立了基于表面增强拉曼散射技术(Surface-enhanced Raman scattering,SERS)的农田水样中微囊藻毒素-LR(Microcystin-LR,MC-LR)的检测方法。采用柠檬酸钠还原法制备金种(Au nanoparticles,Au NPs),通过媒介增长法制备了刺状金纳米颗粒(Spiny gold nanoparticles,SGNPs),使用紫外-可见吸收光谱(Ultraviolet visible,UV-vis)、透射电镜(Transmission electron microscopy,TEM)和探针分子(对巯基苯甲酸,4-mercaptobenzoic acid,4-MBA)对SGNPs进行了表征及鉴定。研究以三角状金纳米颗粒作为基底,选择MC-LR在1 007 cm~(-1)和1 309 cm~(-1)处的特征峰作为定量峰,激光器激发波长为785 nm,积分时间20 s,建立检测方法。本研究建立的检测方法在1.0～100 000μg·L~(-1)的浓度范围内具有良好的线性关系,检测限(LOD)和回收率分别为1.0μg·L~(-1)和80%～102%,使用本方法对镇江市内运粮河及古运河的灌溉水样进行检测,MC-LR的检出率为40%,含量最高达1.81μg·L~(-1),检测结果与LC-MS/MS比对,相关系数为0.84。本研究建立的方法快速准确,前处理简单,能满足农田水样中MC-LR的现场快速检测的要求。  相似文献   

Oceanographic investigation of the American Samoa albacore (Thunnus alalunga) habitat and longline fishing grounds   总被引：1，自引：0，他引：1  

RÉKA DOMOKOS  MICHAEL P. SEKI  JEFFREY J. POLOVINA  DONALD R. HAWN 《Fisheries Oceanography》2007,16(6):555-572

The American Samoa fishing ground is a dynamic region with strong mesoscale eddy activity and temporal variability on scales of <1 week. Seasonal and interannual variability in eddy activity, induced by baroclinic instability that is fueled by horizontal shear between the eastward‐flowing South Equatorial Counter Current (SECC) and the westward‐flowing South Equatorial Current (SEC), seems to play an important role in the performance of the longline fishery for albacore. Mesoscale eddy variability in the American Samoa Exclusive Economic Zone (EEZ) peaks from March to April, when the kinetic energy of the SECC is at its strongest. Longline albacore catch tends to be highest at the eddy edges, while albacore catch per effort (CPUE) shows intra‐annual variability with high CPUE that lags the periods of peak eddy activity by about 2 months. When CPUE is highest, the values are distributed toward the northern half of the EEZ, the region affected most by the SECC. Further indication of the possible importance of the SECC for longline performance is the significant drop in eddy variability in 2004 when compared with that observed in 2003 – resulting from a weak SECC – which was accompanied by a substantial drop in albacore CPUE rates and a lack of northward intensification of CPUE. From an ecosystem perspective, evidence to support higher micronekton biomass in the upper 200 m at eddy boundaries is inconclusive. Albacore's vertical distribution seems to be governed by the presence of prey. Albacore spend most of their time between 150 and 250 m, away from the deep daytime and shallow nighttime sonic scattering layers, at depths coinciding with those of small local maxima in micronekton biomass whose backscattering properties are consistent with those of albacore's preferred prey. Settling depths of longline sets during periods of decreased eddy activity correspond to those most occupied by albacore, possibly contributing to the lower CPUE by reducing catchability through rendering bait less attractive to albacore in the presence of prey.  相似文献   

Specific ion effect of H⁺ on variably charged soil colloid aggregation     

Yekun ZHANG  Rui TIAN  Jia TANG  Hang LI 《土壤圈》2020,30(6):844-852

Specific ion effects (Hofmeister effects) have recently attracted the attention of soil scientists, and it has been found that ionic non-classic polarization plays an important role in the specific ion effect in soil. However, this explanation cannot be applied to H⁺. The aim of this work was to characterize the specific ion effect of H⁺ on variably charged soil (yellow soil) colloid aggregation. The total average aggregation (TAA) rate, critical coagulation concentration (CCC), activation energy, and zeta potential were used to characterize and compare the specific ion effects of H⁺, K⁺, and Na⁺. Results showed that strong specific ion effects of H⁺, K⁺, and Na⁺ existed in variably charged soil colloid aggregation. The TAA rate, CCC, and activation energy were sensitive to H⁺, and the addition of a small amount of H⁺ changed the TAA rate, CCC, and activation energy markedly. The zeta potential results indicated that the specific ion effects of H⁺, K⁺, and Na⁺ on soil colloid aggregation were caused by the specific ion effects of H⁺, K⁺, and Na⁺ on the soil electric field strength. In addition, the origin of the specific ion effect for H⁺ was its chemical adsorption onto surfaces, while those for alkali cations were non-classic polarization. This study indicated that H⁺, which occurs naturally in variably charged soils, will dominate variably charged soil colloid aggregation.  相似文献   

Movements and behaviors of swordfish in the Atlantic and Pacific Oceans examined using pop‐up satellite archival tags     

HEIDI DEWAR  ERIC D. PRINCE  MICHAEL K. MUSYL  RICHARD W. BRILL  CHUGEY SEPULVEDA  JIANGANG LUO  DAVID FOLEY  ERIC S. ORBESEN  DERKE SNODGRASS  R. MICHAEL LAURS  JOHN P. HOOLIHAN  BARBARA A. BLOCK  LIANNE M. MCNAUGHTON 《Fisheries Oceanography》2011,20(3):219-241

Swordfish are highly specialized top‐level predators that have been challenging to study. In this paper, data from 31 pop‐up satellite archival tags attached to swordfish from (i) the eastern Pacific, (ii) central Pacific, and (iii) western North Atlantic‐Caribbean were analyzed. Common across locations was a pronounced diel vertical pattern with daytime hours spent primarily below the thermocline and nighttime hours spent in warmer waters, close to the surface. One exception to this pattern was periodic daytime basking events which were most common in cooler waters off California. Maximum daytime depths were significantly correlated with light penetration as measured by the diffuse attenuation coefficient at 490 nm. Temperature did not appear to influence daytime depths, and swordfish tolerated both extremely low temperatures (4°C) and rapid and dramatic temperature changes (>20°C). Temperature did appear to influence the nighttime depths in the Pacific where fish typically remained in the surface mixed layer. In contrast, in the warm tropical Atlantic this was not the case, and nighttime depths were much deeper. In all areas, nighttime depth increased around the full moon. Given the parallels between the vertical movement patterns of swordfish and those of the deep sound scattering layer we suggest that swordfish vertical distribution patterns, especially during daytime, are influenced largely by resource availability. At night, when swordfish are typically targeted by fisheries, both ambient light and temperature influence movements. Understanding vertical movement patterns of swordfish can help evaluate gear vulnerability, improve population assessments, and potentially reduce fisheries bycatch.  相似文献   

功能化多糖包被的银纳米粒子与阿霉素作用的共振光散射及分析应用     

李靖云  王燚  李原芳 《西南大学学报(自然科学版)》2011,33(1)

将右旋糖酐侧链进行功能化修饰,制备了一种富含醛基的改性多糖.利用这种改性多糖作为还原剂和稳定剂合成银纳米粒子,并研究了该银纳米粒子与阿霉素的相互作用及其共振光散射光谱.研究表明,体系的lg(ΔIRLS)值与阿霉素的浓度在一定范围内呈线性关系,线性方程为lg(ΔIRLS)=0.874 4+0.704 7c,线性范围为1.36×10-6~4.08×10-6mol/L,检出限(3σ)为1.30×10-7mol/L.  相似文献   

蛋白质纳米铁共振光散射探针的研究     

刘玮  董彦莉  何淑平  曹义坡 《安徽农业科学》2008,36(34)

[目的]探索定量测定核酸和蛋白质等生物大分子的方法。[方法]采用Fe(OH)3纳米粒子作为共振光散射探针,研究纳米铁-BSA反应体系测定生物大分子的最优条件及效果。[结果]纳米铁-BSA体系的最佳反应条件是pH值为7.4,纳米铁溶液的加入量为0.5ml,定量测定时选择吸收波长和发射波长均为477 nm。将配好的溶液放置35 min后再进行测定稳定性较好。在上述优化条件下,用该体系测定BSA的线性范围在0.07~0.60μg/ml,线性方程为IRLS=38.0+1583.3C(μg/ml),相关系数为0.99712,检出限为10.2 ng/ml。控制误差在5%以内,该体系对较高浓度的金属离子以及从1.0~100.0μg/ml浓度范围内的氨基酸有很强的抗干扰能力。[结论]该方法简便、快速、可靠且灵敏度高,可用于实际样品的测定。  相似文献   

基于邻域粗糙集和高光谱散射图像的苹果粉质化检测   总被引：1，自引：0，他引：1  

朱启兵  黄敏  赵桂林 《农业机械学报》2011,42(10):154-157,161

研究了基于邻域粗糙集理论的高光谱散射图像苹果粉质化无损检测方法。以576幅波长范围为600~1000nm的苹果高光谱数据为研究对象,利用邻域粗糙集模型对81个原始波段进行选择,从中选择出最优波长子集;利用支持向量机建立分类模型,随机选择526个样本作为训练集,其余50个样本作为测试集,重复仿真10次验证分类能力。仿真结果表明邻域粗糙集能够得到充分表述粉质化程度的14个最优波长,测试模型的平均精度为75%,高于全波长模型的71%和采用主成分分析法的74%。  相似文献   

Research advances of SAR remote sensing for agriculture applications: A review     

Chang-an LIU  Zhong-xin CHEN  Yun SHAO  Jin-song CHEN  Tuya Hasi  Hai-zhu PAN 《农业科学学报》2019,18(3):506-525

Synthetic aperture radar (SAR) is an effective and important technique in monitoring crop and other agricultural targets because its quality does not depend on weather conditions. SAR is sensitive to the geometrical structures and dielectric properties of the targets and has a certain penetration ability to some agricultural targets. The capabilities of SAR for agriculture applications can be organized into three main categories: crop identification and crop planting area statistics, crop and cropland parameter extraction, and crop yield estimation. According to the above concepts, this paper systematically analyses the recent progresses, existing problems and future directions in SAR agricultural remote sensing. In recent years, with the remarkable progresses in SAR remote sensing systems, the available SAR data sources have been greatly enriched. The accuracies of the crop classification and parameter extraction by SAR data have been improved progressively. But the development of modern agriculture has put forwarded higher requirements for SAR remote sensing. For instance, the spatial resolution and revisiting cycle of the SAR sensors, the accuracy of crop classification, the whole phenological period monitoring of crop growth status, the soil moisture inversion under the condition of high vegetation coverage, the integrations of SAR remote sensing retrieval information with hydrological models and/or crop growth models, and so on, still need to be improved. In the future, the joint use of optical and SAR remote sensing data, the application of multi-band multi-dimensional SAR, the precise and high efficient modeling of electromagnetic scattering and parameter extraction of crop and farmland composite scene, the development of light and small SAR systems like those onboard unmanned aerial vehicles and their applications will be active research areas in agriculture remote sensing. This paper concludes that SAR remote sensing has great potential and will play a more significant role in the various fields of agricultural remote sensing.  相似文献