Effects of Dietary Energy Density in the Dry Period on the Production Performance and Metabolism of Dairy Cows

Thirty healthy Holstein dairy cows in the dry period were randomly divided into three groups and fed diets with different net energy for lactation (group A: 1.2 Mcal/kg DM, group B: 1.3 Mcal/kg DM, and group C: 1.4 Mcal/kg DM) for 8 weeks prepartum. Thereafter, dairy cows were fed a diet of the same formulation (1.66 Mcal/kg DM) for 12 weeks postpartum. The effects of different dietary energy densities in the dry period on postpartum performance and metabolic parameters of dairy cows were observed. Milk yield was reduced by 14.5% in the low-energy diet group;however, there were no differences in milk composition between the three groups. Postpartum plasma β-hydroxybutyrate, non-esterified fatty acid, growth hormone, and glucagon levels were significantly decreased whereas leptin and neuropeptide levels were elevated in the low-energy diet group. Moreover, body fat mobilization was attenuated, and the decline in postpartum body condition was reduced in the low-energy diet group, thus effectively reducing the postpartum negative energy balance.

Statistical Prediction of Wet and Dry Periods in theComahue Region (Argentina)

General features of rainy season with excess or deficits are analyzed using standardized precipitation index (SPI) in Limay and Neuquen River basins. Results indicate that most of dry and wet periods persist less than three months in both basins. Furthermore, an increase of rainfall variability over time is observed in the Limay river basin but it is not detected in the Neuquen river basin. There is a tendency for wet (dry) periods to take place in El Ni?o (La Ni?a) years in both basins. Rainfall in both basins, have an important annual cycle with its maximum in winter. In addition, possible causes of extreme rainy seasons over the Limay River Basin are detailed. The main result is that the behavior of low level precipitation systems displacing over the Pacific Ocean in April influences the general hydric situation during the whole rainy season. In order to establish the existence of previous circulation patterns associated with interannual SPI variability, the composite fields of wet and dry years are compared. The result is that rainfall is related to El Ni?o- Southern Oscillation (ENSO) phenomenon and circulation over the Pacific Ocean. The prediction scheme, using multiple linear regressions, showed that 46% of the SPI variance can be explained by this model. The scheme was validated by using a cross-validation method, and significant correlations are detected between observed and forecast SPI. A polynomial model is used and it little improved the linear one, explaining the 49% of the SPI variance. The analysis shows that circulation indicators are useful to predict winter rainfall behavior.

Different characteristics of the structure of atmospheric boundary layer between dry and rainy periods over the northern Tibetan Plateau

In this paper, based on in-situ observational data of the Coordinated Enhanced Observing Period （CEOP） Asia-Australia Monsoon Project （CAMP） on the Tibetan＇Plateau （CAMP-Tibet）, structure of the Atmospheric Boundary Layer （ABL） was preliminarily studied during the dry and rainy seasons. The main results show： （a） Diurnal variation of the ABL is obvious over the northern Tibetan Plateau area. The height of the ABL is different with the season change, which ranges from 2,211 m to 4,430 m during the pre-monsoon season and from 1,006 m to 2,212 m during the monsoon season. The ABL height is higher during the dry period than during the rainyigeriod. （b） The humidity is lower during the dry period than during the rainy period, and there are reverse humidity during both periods. （c） Horizontal wind direction is mostly west during the dry period, east under the height of 2,500 m and west above the height of 2,500 m during the rainy period. The wind speed is low during both the rainy and dry periods in the lower ABL layer. The wind speed is stronger within the upper ABL during the dry period than dtn-ing the rainy period.

Prevalence of bacterial agents isolated from clinical cases of bovine mastitis in the dry period and the determination of their antibiotic sensitivity in Tabriz,Iran

Objective:To determine the prevalence of mastitis-causing bacteria in the dry period and its antibiotic sensitivity.Methods:In this study,852 dry cows were examined.A total of 30 cows with clinical mastitis symptoms were detected and their milk samples were collected.In order to purify the bacteria,brain heart infusion and blood agar media were applied and single colonies were used for Gram staining,oxidase and catalase testing,cultivating in O-F medium to determine the genus and species of bacteria.Then,antimicrobial susceptibility was tested by the agar disk diffusion method.Results:The prevalence of isolated bacteria was 2.46%,in which coagulase positive Staphylococcus,coagulase negative Staphylococcus,Streptococcus dysgalactiae,Streptococcus faecalis,Escherichia coli,Pseudomonas,Bacillus and yeast were(9/99)%,(6/66)%,(13/32)%,(3/33%),(6/66)%,(13/32)%,(9/99)%and(6/66)%,respectively.After tests of antibiotic susceptibility,the most and the least sensitivity were reported to enrofloxacin and ampicillin respectively.Conclusions:This study indicated that Streptococcus dysgalactiae is the most commonly isolated bacteria with the greatest sensitivity to enrofloxacin and tetracycline which can be used to treat mastitis in the dry period in Tabriz.

Characteristics of Temperature Change in China over the Last 2000 years and Spatial Patterns of Dryness/Wetness during Cold and Warm Periods

This paper presents new high-resolution proxies and paleoclimatic reconstructions for studying climate changes in China for the past 2000 years. Multi-proxy synthesized reconstructions show that temperature variation in China has exhibited significant 50–70-yr, 100–120-yr, and 200–250-yr cycles. Results also show that the amplitudes of decadal and centennial temperature variation were 1.3℃ and 0.7℃, respectively, with the latter significantly correlated with long-term changes in solar radiation, especially cold periods, which correspond approximately to sunspot minima. The most rapid warming in China occurred over AD 1870–2000, at a rate of 0.56°± 0.42℃（100 yr）^（-1）; however, temperatures recorded in the 20 th century may not be unprecedented for the last 2000 years, as data show records for the periods AD 981–1100 and AD1201–70 are comparable to the present. The ensemble means of dryness/wetness spatial patterns in eastern China across all centennial warm periods illustrate a tripole pattern： dry south of 25°N, wet from 25°–30°N, and dry to the north of 30°N. However, for all centennial cold periods, this spatial pattern also exhibits a meridional distribution. The increase in precipitation over the monsoonal regions of China associated with the 20 th century warming can primarily be attributed to a mega El Nino–Southern Oscillation and the Atlantic Multidecadal Oscillation. In addition, a significant association between increasing numbers of locusts and dry/cold conditions is found in eastern China. Plague intensity also generally increases in concert with wetness in northern China, while more precipitation is likely to have a negative effect in southern China.

雨前干旱期对生物滞留系统去除氮性能的影响

为应对传统生物滞留系统对雨水径流中氮元素控制效果不稳定的情况,通常在系统底部设置饱和区以强化对氮的去除,但设置饱和区后仍存在多种影响因素可能导致氮泄露。其中雨前干旱期长短关系着系统内部饱和区是否存在,直接影响下一次降雨时系统初期出水中含氮浓度,因此需要深入研究雨前干旱期对系统除氮效果的影响。通过设置带有40 cm饱和区的生物滞留系统,对比不同雨前干旱期条件下系统对污染物的去除效果并分析除氮机理。结果显示,持续进水和短雨前干旱期时系统由于初期出流硝酸盐和总氮浓度低,整体除氮性能良好;长雨前干旱期时系统初期出流硝酸盐和总氮浓度较高,虽然氨氮浓度低,但整体氮去除率较低。不同雨前干旱期条件下污染物去除率存在差异主要是因为干旱期长度会影响填料层和饱和区中氮元素的转化程度,进而影响去除效果。生物滞留系统在干湿交替的条件下基质中硝酸盐异化还原反应占优势地位,这与传统的认为在系统中硝酸盐主要发生反硝化反应有很大差异。

The Influence of Local Rainy and Dry Seasons on the Diurnal Temperature Range in Nigeria

This study analyzed the impact of the local dry and rainy seasons on diurnal temperature range (DTR), for each major climatic zone of Nigeria namely the tropical monsoon, tropical savannah and semi-arid, using meteorological data from thirteen observation stations for the period 1981 to 2021. DTR was computed from the difference of minimum temperature from maximum temperature and yearly and forty one years’ monthly averages of DTR and rainfall were computed and plotted in different graphs. The overall results from each climatic zone showed that DTR fluctuates with the seasons and there is an inverse relationship between DTR and rainfall whereby the value of DTR decreases as the rainy season approaches but increases as the rainy season departs ushering in the dry season or conversely DTR increases as the dry season approaches and decreases as the dry season departs ushering-in the rainy season. Secondly, the average yearly patterns of rainfall and DTR are roughly and oppositely shaped parabolas where the peak value of rainfall is diametrically opposite to the trough value of DTR and the least or nil volume of rainfall corresponds to the highest value of DTR. Thirdly, due to the yearly seasonal cycle of dry and rainy seasons in Nigeria coupled with the inverse relationship between DTR and Rainfall, the seasonal plot of DTR and rainfall is also cyclic in pattern with DTR cycle lagging 180 degrees with the rainfall cycle and the intersection of the two cycles represents the departure of one season and onset of another season while each half-cycle represents either the dry or rainy season. Fourthly, the dependence of DTR on any season at hand in Nigeria makes DTR season-forcing. This fourth result is underpinned by a result that showed that the 1981 and 2021 patterns of DTR and 1981 and 2021 patterns of rainfall when compared were similar, the differences were in the volume of rainfall which was due to climate change that has taken place over the four decades and which also impacted DTR since DTR varies inversely with rainfall. Finally and notwithstanding the common grounds of the results stated above, the result further showed that each climatic zone of Nigeria reacts differently to the local and global climate changes leading to the magnitude of DTR and the volume of rainfall being different across climatic zones, with rainfall volume and duration decreasing towards the arid North from the Coastal South while contrariwise DTR increases towards the arid North from the Coastal South.

不同发酵时期对黑蒜调味粉品质的影响

黑蒜富含微量元素与营养物质,作为一种食品或保健品在市面上流行。黑蒜的品质也引起了人们的广泛关注。普通黑蒜是用新鲜完整的带皮生蒜在高温高湿的发酵箱中自然发酵90~120 d后制成的。然而生蒜是如何在发酵过程中逐渐变黑、黑蒜与生蒜极大的口感差别以及两者营养价值的变化基于什么成为人们疑惑的问题。该研究选取品相完好的紫皮独头蒜,在专业的黑蒜发酵锅中发酵10 d,获得发酵成功的黑蒜,并在发酵过程中对不同发酵时期的黑蒜进行质构测定,经过干燥破碎,制成调味蒜粉,并对其中的还原糖含量、总酸含量、总酚含量、水分含量、粗脂肪含量、蛋白质含量进行测定,由此探寻蒜在发酵过程中产生的变化,从而对不同发酵时期黑蒜调味粉的品质进行综合评价。该研究可拓展关于调味品发酵方面的知识,为提高新型功能性调味粉的营养价值提供更多的数据资源。

前期晴天数对不同材质屋面径流污染特征的影响

以城市典型屋面材质(油毡、塑钢、瓦)为研究对象,通过人工模拟降雨考察不同前期晴天数对不同材质屋面径流污染特征的影响。结果表明,不同材质屋面径流中悬浮物(SS)、化学需氧量(COD)、总磷(TP)和总氮(TN)的场次降雨径流平均浓度由大到小都依次为油毡屋面、瓦屋面和塑钢屋面。不同材质屋面径流中重金属的场次降雨径流平均浓度各不相同。总体而言,污染物浓度随前期晴天数增加而增大,主要是小粒径的颗粒物体积分数增加,而大粒径的颗粒物体积分数反而减小。屋面径流中SS是COD、TP和重金属的主要载体,污染物与小粒径的颗粒物相关性更高,因此要想控制屋面径流中的COD、TP和重金属,关键是控制细小的颗粒物。

干乳期奶牛隐性乳腺炎主要致病菌的分离、鉴定及2种抗菌药物的体外抗菌效果评价

[目的]对新疆维吾尔自治区奶牛隐性乳腺炎常见致病菌进行分离、鉴定,评价头孢洛宁和利福昔明对临床分离菌株的体外抗菌效果。[方法]采用兰州隐性乳腺炎诊断液对新疆维吾尔自治区昌吉回族自治州某奶牛养殖场的干乳期奶牛进行诊断;利用平板划线法及细菌16S rDNA序列分析法对采集的74份乳样进行细菌分离及种属鉴定;应用微量肉汤稀释法测定头孢洛宁和利福昔明对致病菌临床分离株的最低抑菌浓度(MIC)以及最低杀菌浓度(MBC)。[结果]从74份乳样中共分离、鉴定致病菌9种、103株,其中,金黄色葡萄球菌35株,占总菌株数量的33.98%;大肠杆菌24株,占总菌株数量的23.30%;产色葡萄球菌15株,占总菌株数量的14.56%;模仿葡萄球菌(10株)、表皮葡萄球菌(6株)、屎肠球菌(5株)、溶血性葡萄球菌(4株)、地衣芽孢杆菌(3株)和腐生葡萄球菌(1株)的数量分别占总菌株数量的9.70%、5.83%、4.85%、3.88%、2.91%、0.97%。体外抗菌试验结果显示,头孢洛宁对金黄色葡萄球菌、大肠杆菌、产色葡萄球菌、溶血性葡萄球菌、表皮葡萄球菌、腐生葡萄球菌、屎肠球菌、模仿葡萄球菌和地衣芽孢杆菌的MIC分别为0.12、3.91、0.98、0.06、0.98、0.98、3.91、0.06、0.49μg/mL,MBC分别为0.24、7.81、1.95、0.12、1.95、1.95、7.81、0.24、1.95μg/mL;利福昔明对金黄色葡萄球菌、大肠杆菌、产色葡萄球菌、溶血性葡萄球菌、表皮葡萄球菌、腐生葡萄球菌、屎肠球菌、模仿葡萄球菌和地衣芽孢杆菌的MIC分别为0.20、6.25、1.56、0.78、1.56、1.56、12.50、0.20、0.20μg/mL,MBC分别为0.78、12.50、3.13、1.56、3.13、3.13、12.50、0.78、1.56μg/mL。[结论]引起该养殖场干乳期奶牛隐性乳腺炎的主要致病菌为金黄色葡萄球菌、大肠杆菌、产色葡萄球菌;头孢洛宁和利福昔明对临床分离的致病菌株均有良好的抑菌效果。

新研7号和隆跃99挑旗后干物质积累及灌浆特性分析

为探明大穗大粒型小麦品种新研7号、隆跃99挑旗后叶面积衰落、干物质积累和籽粒灌浆特性,在品种展示田中每8~9 d取20个单茎地上部分,测定叶面积、烘干质量;标记同日扬花单穗,每4~5 d一次剥取20穗中部10小穗籽粒,计数后测烘干质量。结果显示,新研7号、隆跃99单茎质量、干物质积累量和花后群体干物质量高于济麦22,叶片衰老慢、功能期长,渐增、快增阶段和最大、平均灌浆速率高于济麦22。说明新研7号、隆跃99具有大穗大粒生理基础,高产栽培要以主茎成穗为主。

改性填料在城市污水处理厂提标改造中的应用

介绍了采用改性填料的MBBR工艺在山西省长治市污水处理厂提标改造工程中的应用。该升级改造工程规模为10万m^(3)/d,采用Bardenpho+MBBR工艺对原Bardenpho工艺进行了升级改造,在没有扩建池容的基础上,通过增加填料膜面积及相关设备,出水污染物中的COD、氨氮、总磷达到《地面水环境质量标准》(GB3838-2002)中的Ⅴ类标准。实际运行显示,采用改性填料的MBBR工艺处理效果较好,出水水质稳定。

收割时间与加工方式对天然牧草产品品质和体外消化率的影响

为探明呼伦贝尔地区适宜天然牧草收割时间以及青贮的可行性,在2022年的7月11日(T_(1)组)、7月16日(T_(2)组)、7月21日(T_(3)组)、7月26日(T_(4)组)和7月31日(T_(5)组)收割天然牧草,采用天然干燥、青贮发酵和人工干燥3种方式加工天然牧草,评价其发酵品质、营养品质和体外消化率。结果表明:5个时间收割调制的天然牧草青贮饲料发酵品质均较好,天然牧草青贮饲料T_(3)和T_(4)组乳酸(LA)和乙酸(AA)含量较高,pH值和氨态氮/总氮(NH3-N/TN)较低。青贮发酵组相较于天然干燥组,T_(2)、T_(3)、T_(4)和T_(5)组收割的天然牧草,粗蛋白质(CP)含量显著增加(P<0.05),可溶性碳水化合物(WSC)含量显著降低(P<0.05),中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)含量差异不显著(P>0.05);各个时间收割的天然牧草的干物质体外消化率(IVDMD)和粗蛋白质体外消化率(IVCPD)显著增加(P<0.05)。青贮发酵组、天然干燥组和人工干燥组中,T_(4)组收割天然牧草的CP含量均最高,NDF和ADF含量较低,IVDMD和IVCPD较高。天然牧草青贮饲料的营养品质和体外消化率高于天然干燥调制的干草,在7月26日收割的天然牧草青贮饲料品质最好,建议在7月下旬中期收割天然牧草并进行青贮。

漳江口溶解态稀土元素的地球化学特征及影响因素

河口区域稀土元素(Rare earth elements, REEs)的地球化学行为对理解海洋中REEs的循环具有重要意义。本文通过现场调查对2018年9月(暴雨时期)、2019年12月(旱季)及2020年8月(湿季)溶解态REEs在漳江口的分布特征、REEs的主要影响因素及人为稀土元素钆(Gd)污染进行研究。结果表明:漳江口溶解态REEs在不同时期的分布及分异存在显著差异,溶解态REEs含量暴雨时期>旱季>湿季。暴雨时期溶解态REEs主要呈现轻/中稀土相对富集及Ce正异常现象,而旱季及湿季溶解态REEs主要呈现重稀土相对富集及Ce负异常现象,颗粒物-水作用是不同时期溶解态REEs含量及分异存在差异的主要原因。Gd在不同时期均呈现正异常,暴雨时期、旱季及湿季人为Gd占比分别为18%~29%、26%~69%及22%~60%,推测Gd污染可能受河口上游医院核磁共振造影剂使用的影响。以上研究表明暴雨导致的颗粒物释放对河口溶解态REEs具有显著的贡献,今后研究需要重视特殊事件(如暴雨)对河口溶解态REEs来源和收支的影响。漳江口上游的人口密度相比全国其他地区较低但存在较为严重的人为Gd污染,说明我国其他河口人为稀土污染及来源也应引起广泛的重视。

高光谱图像结合卷积神经网络的马铃薯干腐病潜育期识别

马铃薯是世界第四大粮食作物,具有丰富的营养价值。但其在贮藏和运输过程中易被镰刀真菌侵染而产生干腐病,最终造成巨大资源浪费和经济损失,因此实现马铃薯干腐病的早期快速无损检测是必要的。在样品被病原菌侵染时,经历了健康—潜育期—轻度病害—重度病害的阶段,其中潜育期的样品难以识别,主要源于病害发生时间较短,表面未形成肉眼可见的病斑,与健康样品相似。为了实现马铃薯干腐病潜育期的识别,结合高光谱成像和深度学习展开马铃薯干腐病早期诊断研究。以健康和不同腐败程度马铃薯为实验对象,获取健康和不同病害等级的马铃薯高光谱图像。然后基于ENVI人工选取健康部位和不同腐败程度样品的病斑部位为感兴趣区域(ROI),并计算ROI的平均光谱值作为该样品的最终光谱信息。以光谱数据作为输入变量,病害等级作为输出变量,建立卷积神经网络(CNN)模型,并对其网络结构进行优化,对比分析不同模型的预测结果,筛选出最优网络层模型为Model_3_3。并基于此结构进行学习率的优化,得到Model_0.0001识别效果最好,其总体准确率、精度、灵敏度和特异性分别为99.68%、99.76%、98.82%、99.54%。为了进一步突显CNN应用于马铃薯干腐病潜育期识别的优势,建立了最小二乘支持向量机(LS-SVM)、随机森林(RF)、K-近邻法(KNN)和线性判别分析(LDA)模型。结果显示,四种常规算法模型的识别准确率分别为90.77%、92.30%、93.10%和92.34%,其中对潜育期样品识别率分别为91.00%、85.58%、94.18%和90.33%。对于总体准确率,CNN模型较几种常规方法提高了6.58%~8.91%;对于潜育期样品的识别,CNN模型较常规方法提高了5.55%~14.15%。研究表明,高光谱成像技术结合CNN可以有效实现马铃薯干腐病潜育期识别,为提高马铃薯病害早期诊断的智能化水平提供了参考方法。

授粉期高温胁迫对夏玉米植株形态、叶片光合及产量的影响

针对黄淮海地区花期高温影响夏玉米安全生产的问题,本研究以热敏感型品种‘先玉335’为试验材料,以大田常温为对照(CK),设置授粉期高温处理(HT),研究授粉期高温胁迫对夏玉米植株形态、叶片光合特性、干物质积累与分配及产量形成的影响。结果表明:2021年和2022年,HT处理的冠层最高温度超过40℃的天数分别为7 d和8 d,高温处理期间冠层最高温度分别较CK高1.7~6.8℃和1.5~4.6℃。HT处理显著提高了夏玉米株高和穗位高,对茎粗和叶面积无显著影响,但延缓了生育后期叶片衰老,2021年和2022年成熟期的叶面积较CK分别显著提高34.69%和163.72%。高温处理期间,HT处理的玉米叶片气孔导度、蒸腾速率和胞间CO_(2)浓度显著升高(P<0.05,P<0.01),叶片羧化效率、气孔限制值和水分利用效率显著降低(P<0.05,P<0.01);叶片净光合速率随处理温度而变化,处理温度过高(一般>40℃时)则显著降低(P<0.05),反之则显著升高(P<0.05)或无显著变化,叶片整体光合性能下降。高温胁迫解除后,HT处理的叶片光合性能相关参数逐渐与CK趋于一致。经授粉期高温胁迫处理后,玉米茎秆、叶片、苞叶、穗轴和单株干重降低,其中穗轴干重降幅最大,而雄穗和花丝干重增加,使得干物质向茎秆、叶片、雄穗、花丝等部位的分配比例增加,而向穗轴的分配比例显著减少(P<0.05)。至成熟期,HT处理造成玉米籽粒和单株干重显著减少48.32%和16.71%(P<0.05),而玉米茎秆和叶片干重显著增加35.01%和9.48%(P<0.05)。HT处理的结实率和穗粒数分别显著下降54.43%和53.19%(P<0.05),百粒重显著提高10.13%(P<0.05),但籽粒产量显著降低46.82%(P<0.05)。综上,授粉期高温胁迫增强了玉米叶片气孔蒸腾,增加了胞间CO_(2)浓度,降低了叶片羧化效率和水分利用效率,导致植株整体光合性能下降,制约了光合同化物积累及向穗部的转移分配,导致结实率显著下降,穗粒数显著减少,制约了花后光合同化物从“源”(茎秆和叶片)向“库”(籽粒)的转运,最终导致籽粒产量大幅下降。

超干处理对菜豆种子活力及生理生化活性的影响

本研究旨在应用硅胶干燥的方法对菜豆进行超干处理,分析其主要生理活性相关指标,以期为菜豆种子的长期储藏提供科学依据和实践参考。超干处理后,应用考马斯亮蓝G-250染色法、TTC法、硫代巴比妥酸(TBA)法等测定蛋白质含量、脱氢酶(ADH)含量等指标。结果表明‘将军’含水量在6.95%时,种子活力及生理指标均高于对照,而抗氧化酶的活性显著低于对照;‘紫冠’含水量在6.89%时,各项生理指标均高于对照,O2-含量下降;‘热那亚’含水量在6.15%时,发芽率最高,蛋白含量、ADH活性明显上升,O2-含量、MDA不显著。这表明适度超干处理对‘将军’种子影响较大,对‘紫冠’、和‘热那亚’影响较小或者没有影响。通过试验结果可知,超干处理对于保存菜豆种子是可行的,为菜豆种子的长期储藏奠定下基础。

氮素不同控释期对甘薯光合特性及干物质积累与分配的影响

以甘薯[Ipomoea batatas(L.)Lam.]品种济薯25为试材,在大田条件下,设置控释期为30 d(T30)、50 d(T50)、70 d(T70)、90 d(T90)4个氮素控释肥处理,以施用等量养分含量的普通复合肥作为对照(CK),研究不同氮素控释期对甘薯光合特性及干物质积累与分配的影响。结果表明,氮素适当控释(控释期30~70 d)提高了甘薯中后期(80~160 d)叶片光合性能,促进了干物质向地下部的快速积累和转运分配,甘薯中后期叶片光合指标、地下部干物质积累(积累量和积累速率)和分配(分配比例和根冠比)指标均明显高于对照,其中以T50、T70较好,收获期(160 d)2个处理净光合速率、叶绿素SPAD、地下部干物质积累量、根冠比分别比对照提高了14.01%、11.32%、21.75%、18.48%和15.62%、11.84%、20.65%、18.84%;当控释期达90 d时,后期(120~160 d)地下部干物质积累与分配指标均低于对照,说明氮素控释期过长不利于甘薯后期干物质向地下部的快速积累和转运分配。

干湿交替环境下材料腐蚀行为研究进展

随着海洋资源的开发与利用,干湿交替环境下材料的腐蚀与防护越来越受到关注。在浪花飞溅区、潮差区、含有腐蚀性介质的大气环境中、使用除冰盐/融雪剂的设施和建筑、干湿交替区域的钢筋混凝土结构以及干湿交替砂土环境中,材料长期经受含水腐蚀性介质随温度和湿度变化引起的干湿交替循环作用,其腐蚀行为与干燥及全浸环境中有所不同。本文综述了干湿交替环境下国内外研究现状与进展,包括多种材料在不同干湿交替环境下的腐蚀行为、腐蚀影响因素、腐蚀试验方法等,以期为材料的研究与应用提供一定的理论经验。

Research on Constant-Speed Rapeseed Drying Mechanism

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