PVC单、双壁波纹塑料管用作农田排水暗管比较研究

通过室内材料力学试验和水力学试验，对PVC单、双壁波纹塑料管有关性质进行了比较研究，试验结果表明：PVC双壁波纹塑料管的力学性质和水力学性质均较单壁波纹塑料管优越，适于作农田地下排水暗管。     

玉米荫蔽对大豆光合特性与叶脉、气孔特征的影响

目的 探究在玉米-大豆套作模式下,玉米大豆共生期内玉米荫蔽对大豆光合特性及叶脉、气孔特征的影响。方法 在自然光照射下采用两因素完全随机盆栽试验,以强耐荫性品种南豆12和弱耐荫性品种桂夏3号为研究对象,设置T1（2行玉米间隔2行大豆套作）、T2（1行玉米间隔1行大豆套作）和CK（净作大豆）3种空间配置,探究不同处理下大豆光合参数、叶脉和气孔特征参数对光环境的响应。结果 与净作相比,玉米荫蔽下大豆冠层的远红光光谱辐照度显著增加,T1、T2处理下的光照强度分别降低48.62%和77.39%。在玉米荫蔽下大豆的净光合速率、气孔导度、叶脉密度和气孔密度显著低于CK（P＜0.05）,且下降幅度都随着荫蔽程度的增加而增加（由T1到T2处理）。与CK相比,T1、T2处理下南豆12的净光合速率分别显著下降41.00%、44.15%,桂夏3号的净光合速率分别显著下降44.62%、47.93%;南豆12的气孔导度分别显著下降29.19%、39.69%,桂夏3号的气孔导度分别显著下降26.83%、49.50%。同时,南豆12的叶脉密度在T1、T2处理下分别比CK显著下降14.99%、20.01%,气孔密度分别下降12.79%、18.27%;桂夏3号的叶脉密度在T1、T2处理下分别比CK显著下降10.38%、27.62%,气孔密度分别下降15.77%、22.46%。此外,大豆的净光合速率与气孔导度、叶脉闭合度、气孔密度、叶脉密度呈显著正相关关系（P＜0.05）,与叶脉间距呈极显著负相关关系（P＜0.01）;叶脉密度与气孔密度呈极显著正相关关系（P＜0.01）。玉米荫蔽下,南豆12的叶脉密度、叶脉长度、叶脉闭合度、叶脉间距都显著优于桂夏3号。在荫蔽程度更高的T2处理下,除蒸腾速率和叶脉闭合度以外,强耐荫性品种南豆12的光合、叶脉和气孔各参数的变化幅度都小于桂夏3号,且净光合速率更高。结论 在玉米-大豆套作的种植模式中,大豆冠层光环境、叶脉和气孔特征的变化会影响大豆的光合能力,但不同耐荫性大豆品种的叶脉、气孔特征对荫蔽的响应存在差异。     

上部叶烘烤过程中叶片与主脉含水率变化对烤烟质量的影响

为进一步了解上部烟叶烘烤特性,探究叶片与主脉失水的动态协调关系,采用高温高湿变黄的方法,研究了上部叶烘烤过程中叶片与主脉含水率变化对烟叶烘烤质量的影响。结果表明,变黄期处理与对照均易变黄,定色期处理定色效果较好,干筋期对照主脉较难干燥,处理烤后上等烟比例明显高于对照。变黄期通过高温高湿的方法使叶片凋萎与主脉发软同步,能够有效提高烤后烟质量,从而提高上部叶的可用性。     

PVC双壁波纹排水暗管开孔率试验研究

采用一维渗流试验装置研究了ＰＶＣ双壁波纹管用作农田排水时的适宜开孔率，试验表明：ＰＶＣ双壁波纹管用作农田排水暗管时开孔率不必要求过高，控制在２．５％￣３．０％之间即可满足生产要求。     

Anatomic variations of feline internal and external jugular veins

We evaluated 50 feline head and neck computed tomography examinations to determine the prevalence of vascular variation in the internal and external jugular veins. We identified three distinct anatomic conformations of the internal jugular vein. No variation of external jugular vein morphology was detected. Feline patients can have different internal jugular vein morphology that should be recognized for surgical planning.     

Construction and expression of reconstructive plasmids with human thrombomodulin gene

AIM: To provide experimental evidence for gene therapy of thrombophilia disease, we constructed the eukaryotic expression plasmid with human thrombomodulin (hTM) gene and observed the alteration of hTM expression on the surface of human umbilical vein endothelial cells (HUVECs) with and without the reconstructive plasmid. METHODS: The whole expressive fragment of hTM gene was amplified by PCR from human genome. Both hTM gene and pcDNA3.1(+)/neo empty vector was digested by HindⅢ and EcoRⅠ. Two digested fragments were ligated into pcDNA3.1/hTM with T₄DNA ligase. After identifying, the reconstructive plasmid transfected into HUVECs using lipofectin. The hTM antigen on the HUVECs was detected by immunohistochemistry. RESULTS: The hTM reconstructive plasmid was confirmed by double endonuclease redigesting and sequencing. About 10% HUVECs were transfected by pcDNA3.1/hTM plasmid with lipofectin and the high-level hTM was detected on the transfected cells. CONCLUSION: We constructed the pcDNA3.1/hTM plasmid successfully, and it could be expressed on the HUVECs.     

Symptomless Spread of Blight-inducing Strains of Xanthomonas campestris pv. campestris on Cabbage Seedlings in Misted Seedbeds

Xanthomonas campestris pv. campestris induces two types of symptoms, namely, black rot and blight. Black rot symptoms are V-shaped lesions and black veins on the leaf, and blight symptoms are sudden collapse of interveinal tissues following the lack of veinal necrosis at early stages of infection. These two symptoms can occur simultaneously. However, the tendency to induce either symptom type is strain-dependent. Six strains were evaluated for their rate and pattern of spread in misted seedbeds by using strain-specific monoclonal antibodies and miniplate enrichment/ELISA. Data on pathogen incidence was defined as the presence of the pathogen in or on plants rather than visual symptoms. The results indicated that blight-inducing strains spread to more seedlings than black rot-inducing strains. The high incidences of blight-inducing strains in experimental plots were associated with non-randomness of spatial pattern of pathogen spread, indicating that high incidence is primarily due to the spread from adjacent plants by leaf contact and water splash. Most ELISA-positive seedlings were symptomless, indicating that the sensitivity of the system used in this study was adequate for detection of latent or epiphytic spread.     

猪脐静脉血管内皮细胞永生化的初步研究

为了建立稳定的血管内皮细胞系,进而为研究猪瘟病毒致病机理提供理想的细胞模型,将脂质体转染的pCIneo-hTERT质粒导入原代猪脐静脉血管内皮细胞中,经G418抗性筛选,挑取阳性克隆并扩大培养。对转染后的细胞进行形态观察,研究其增殖及生长特征,并对其端粒酶活性进行了鉴定。结果表明,转染细胞单层贴壁生长,有接触抑制性,呈铺路石状;F-ⅧAg和CD34免疫荧光鉴定阳性,具有转染前细胞特征;转染后细胞培养代数增加,传至第10代和15代转染后细胞端粒酶活性检测为阳性。说明hTERT转染可以延长猪血管内皮细胞的寿命。     

Nutritional parameters in the blood of dams during late gestation and immediately after calving,in the umbilical vein at calving,and in the blood of calves immediately following birth in Holstein heifers pregnant with either Holstein or beef breed fetuses

Dairy cattle management lacks consideration of fetal breed, the effect of which on fetal growth and nutrition are unclear. We investigated blood parameters in 12 late-pregnant Holstein heifers with similar (Holstein, n = 5) or different (Japanese Black [n = 4] or F1 cross [n = 3]; Holstein × Japanese Black) fetus breeds and in their umbilical cords and calves. Samples were obtained from dams 1 week before calving (−1 week) and immediately after calving, from the umbilical vein at calving, and from calves immediately after birth. Dams with beef fetuses had higher serum glucose levels (−1 week; p < .05) than those with Holstein fetuses. Plasma total amino acid, total essential amino acid, total nonessential amino acid, and other amino acid concentrations were lower in the umbilical veins of dams with calves of the beef breeds than in those of the Holstein breeds (p < .05). Furthermore, serum glucose and plasma amino acid levels were lower in the beef calves than in the Holstein calves (p < .05). Overall, nutrient supply from dams to beef fetuses was lower than that to Holstein fetuses. Our findings may facilitate feeding management of dairy cattle pregnant with beef breeds for appropriate fetal growth and nutrition.     

记新种霍山透翅蛾

透翅蛾科Paranthreninae亚科的Cissuvora属以前仅知1种,即产自北美的C.ampelapsis Engelhardt(1946).目前发现了1新种Cissuvora huoshanensis Xu,这是该属在我国的首次记载.