球面圆弧锥齿轮接触点轨迹方程

为了提高农业机械等领域的中央传动系统中齿轮的承载能力,减小中央传动的总体尺寸,降低机构的离地间隙,研究了一类理想状态下的球面圆弧锥齿轮。该文根据圆弧锥齿轮的啮合原理、坐标转换以及球面三角几何的方法,确定了球面圆弧锥齿轮接触点轨迹方程和齿轮副圆弧齿廓齿面方程,进一步完善了球面圆弧锥齿轮的设计理论,并根据研究出的方程,进行了齿轮的三维造型,为正确的设计和加工大端面呈理想球面且螺旋齿形端面为圆弧齿廓的球面圆弧螺旋锥齿轮提供了理论基础,也为后续的球面圆弧锥齿轮的参数化设计和数字化加工提供了研究基础。     

黄瓜根边缘细胞生物学特性及其对铝的响应

 以黄瓜为试验材料, 研究了黄瓜根边缘细胞的生物学特性及其对铝毒的响应。试验结果表明,在黄瓜种子萌发过程中, 根边缘细胞有很高的活性。当根长度在25 mm, 根边缘细胞数目达到最高值5 480个, 根伸长到10 mm时, PME (果胶甲基酯酶) 相对活性达到最高值, 然后随着根的伸长, PME相对活性逐渐下降。在铝处理的条件下, 黄瓜根长及边缘细胞的存活率会随着铝液浓度的升高依次递减, 说明铝毒对根的发育有明显的抑制作用及危害, 而根冠的PME活性却有所提高, 说明了PME与植物铝毒胁迫之间存在着相关性。铝毒条件下边缘细胞PME活性的提高, 使细胞壁的果胶去甲基化, 增加了Al³⁺的结合位点, 从而避免铝更多地进入细胞内, 造成对植物的毒害。     

Growth of hydrogenotrophic and acetoclastic methanogens on substrate from rice plant callus cells in anaerobic soil: an estimation to the role of slough-off root cap cells to their growth

Flooded paddy fields are the major anthropogenic sources of methane (CH₄) emission, and organic materials of rice plant origin were estimated to be important as its source. This study used rice (Oryza sativa L. cv, Yukihikari) callus cells as a model material for slough-off root cap cells, and carbon-13 (¹³C)-labelled callus cells were subjected to decomposition in aerobic and anaerobic soil microcosms for 56 days. DNA was extracted from a soil incubated with carbon-12 (¹²C)- and ¹³C-callus cells and subjected to buoyant density gradient centrifugation to identify methanogenic archaeal species that assimilated carbon from the callus cells. ¹³C-labelled 16S rRNA gene (16S rDNA) fragments from methanogenic archaea were not polymerase chain reaction (PCR)-amplified in heavy fractions under aerobic soil conditions, while they were successfully done from day 3 onwards under anaerobic soil conditions. Eighty-four denaturing gradient gel electrophoresis (DGGE) bands in heavy fractions were sequenced, revealing that they were members of Methanosarcina spp. (20 clones), Methanosaeta spp. (18 clones), Methanocella spp. (25 clones), Methanomicrobiales (10 clones), Methanobacterium spp. (7 clones) and Cluster ZC-I (2 clones). They included hydrogenotrophic and acetoclastic methanogens and were phylogenetically different from those residing in rice roots and, presumably, from those assimilating root exudate and mucilage-derived carbon. This study indicates that carbon of slough-off root cap cells propagates specific methanogenic species in rice rhizosphere under anaerobic soil conditions and thus augments the diversity of the total rhizospheric methanogenic community.     

基于穗帽变换的TM影像水稻面积提取

利用水稻生育前期和后期两个不同时期TM影像分别进行穗帽变换生成亮度、绿度和湿度变量,并将它们合成为多时相影像,充分利用这3个具有物理意义的变量,特别是湿度变量进行水稻种植区影像分类和以水为背景的水稻面积提取,并使用亚米级GPS地面调查的数据进行分类验证。 基于穗帽变换影像的分类方法有效提高了水稻面积提取精度,水稻分类的生产者精度和用户精度分别为84.30％和85.18％,这比原始合成影像数据的分类结果提高了约3个百分点;另外,总精度也由原始合成影像的74.12％提高到经过穗帽变换的78.04％。     

平菇品种比较试验

近几年,北京地区平菇的栽培发展迅速,为了选择适合本地的平菇品种,试验对55个平菇菌株进行品种比较。55个供试品种全部为我国各地的主要栽培品种,由中国农业微生物菌种保藏管理中心(ACCC)收集保藏。     

基于多角度高光谱CHRIS影像的隆宝滩湿地遥感分类方法研究

采用青海省隆宝滩地区的多角度高光谱CHRIS遥感数据,通过研究+36°、0°和-36°三个角度影像的组合变换,提出影像变换+不同角度波段组合的方法,用以获取地物的分类信息。该方法首先对0°影像进行穗帽变换,选择其湿度图像,再与+36°和-36°影像的第4波段(0.461 μm)进行RGB组合,生成新的彩色合成影像,然后再进行支持向量机(SVM)的监督分类。结果显示,利用该方法对隆宝滩湿地分类的精度可达到90.02％;而利用传统的监督分类对0°影像直接进行分类,其精度为75.46%。由此可见,利用不同角度信息进行波段组合的方法,大大提高了高光谱影像进行湿地信息提取的精度,为湿地信息提取提供了一个有效的方法。     

Analysis of Immune Response Induced by Recombinant Lactobacillus reuteri Expressing Cap Protein of Porcine Circovirus Type 2 in Mice

The purpose of this study was to construct a recombinant Lactobacillus reuteri (L. reuteri) expressing the cap protein of porcine circovirus type 2 (PCV2) and evaluate its effect on immune response in mice. The cap protein gene of PCV2b strain isolated and stored in the laboratory was amplified by PCR. A recombinant strain pPG-T7 g10-PPT-cap / L. reuteri expressing the cap protein was constructed using L. reuteri of pig origin as the host strain and explored the immune effect of BALB/c mice with recombinant bacteria orogastrically. Indirect ELISA was used to determine the level of antigen-specific IgG antibodies in the serum of mice after immunization, the levels of antigen-specific sIgA antibodies in stool, nasal wash, reproductive tract wash, and intestinal mucus, and the levels of various cytokines in mouse serum; MTT method was used to detect mouse spleen lymphocyte proliferation levels; flow cytometry (FCM) was used to detect the levels of CD4⁺ T cells and CD8⁺ T cells in mouse spleen lymphocytes; fluorescence quantitative PCR was used to detect the viral load of organs in challenged mice after immunization. The results showed that the serum levels of IgG antibodies in the mice of the oral immune recombinant strain group (OIG) were significantly higher than those in the control group (P<0.01); the levels of sIgA antibodies in the stool, nasal wash, reproductive tract wash, and intestinal mucus of the mice in OIG were significantly higher than those in the control group (P<0.01); Compared with the control group, the levels of cytokines in the serum of OIG were as follows: The levels of IFN-γ, IL-2, IL-4, IL-12 increased, the levels of IL-10 decreased, and the levels of IFN-α did not change significantly; Incubation of PCV2 and mouse spleen lymphocytes in vitro showed that the proliferation stimulating index of spleen lymphocytes in OIG was significantly higher than that of the control group (P<0.01); FCM results showed that CD4⁺ T cells and CD8⁺ T cells were higher than those of the control group; the results of fluorescent quantitative PCR showed that compared with the control group, the viral load in the OIG was significantly lower than that of the control group. In summary, the recombinant L. reuteri expressing the PCV2 cap protein were successfully constructed, and the constructed recombinant L. reuteri can stimulate mice to produce humoral and cellular immune responses after oragastrical immunization, and can exert a certain immune protection effect.     

热磨机磨盘真实间隙非接触测量的研究

目前普遍采用接触式测量方法不能实时反映磨片磨损后的真实间隙。本文对采用电涡流传感器和超声波测厚仪组合实时非接触测量磨盘真实间隙的设计方案进行了研究和探讨。     

HMC毒素对雄花不育及正常细胞质玉米根冠活细胞的影响

本文分析了三套(T、C、S、N)与20对(C、N)玉米同核异质系,在25℃条件下,经 C 毒素(HMC)处理3小时后,观察根冠细胞的死亡率。结果表明,C 细胞质的细胞死亡率均高于其它同核异质系。因此,C 毒素对 C 细胞质的毒害作用是特异性的,同时也为快速鉴定玉米雄花不育细胞质提供了一种新方法。     

玉米籽粒的尖端和胚部的计算机视觉识别

对影响计算机视觉检测玉米籽粒品质的尖端和胚部的识别两个问题进行了研究。利用玉米籽粒尖端的形态特征和胚部图像的亮度特征，分别提出了相应的识别算法。算法对4个品种xhg、xn12、wn14、wc玉米籽粒尖端、表面特征的综合识别率分别为92.50%和89.58%，为特征参数计算奠定了基础。