Characteristics and thermodynamics analysis ofoxyacetylene flame brazing joint of Cu/Al tubes

以磨盘柿为试材,研究不同液浸处理对冰温贮藏(-0.5～-0.2)℃柿果涩味转变、品质及生理指标的影响。结果表明:在冰温条件下,用2%浓度的NaCl溶液贮藏磨盘柿,可使果实的乙醇含量在贮藏30～45 d内急剧增加,促进可溶性单宁的降低,在贮藏45 d时达到完全脱涩,并可有效延缓果实硬度的下降,具有脱涩和保脆的双重作用,同时可保持相对较高的可溶性固形物和可滴定酸含量,抑制贮藏后期果实丙二醛和膜相对电导率的增加,减缓果实的衰老进程。     

高硼胁迫对观赏凤梨植株生长和元素含量的影响

以观赏凤梨为试材,研究了高硼胁迫对植株生长、叶绿素含量、可溶性糖和淀粉含量、元素含量的影响。结果表明,与不施硼相比,施硼抑制了观赏凤梨地上部和根系的生长,随硼浓度增加,抑制程度增加;施硼引起植株中下部叶片叶尖发黄焦枯坏死,叶片叶绿素含量降低;施硼引起叶片和根系可溶性糖和淀粉含量下降;施硼提高了根系N、P、Fe、Mn、Zn含量,但降低了叶片这些元素含量,引起叶片和根系Cu含量的下降。表明,观赏凤梨对硼过量的反应非常敏感,栽培基质或灌溉水中含硼不利于观赏凤梨植株生长。     

早熟柑橘黄龙病空间格局参数特征及其应用

为了揭示柑橘早熟宫川黄龙病的空间分布信息和病株行为特征,2004-2009年采取多级抽样法于每年11月上旬在果实成熟期对2块定点样地逐株进行病级调查,取得了12组样本资料,应用聚集度指标法、Iwao 法和Taylor法等对其空间分布型进行测定检验,结果表明柑橘黄龙病在早熟宫川果园呈聚集分布,其聚集强度是随着病级升高而增加。其聚集原因经Blackith种群聚集均数测定,当m<2.1184时,其聚集是由于某些环境如气候、栽培条件、植株生育状况等所引起的;当m≥2.1184时,其聚集是由病株本身的聚集行为与环境条件综合影响所致。在此基础上提出了理论抽样数和序贯抽样模型：n=(1/D)2?[1/m+0.6761] 和Tn=1.831 /[D02-0.1581 /n]。     

矮生沿阶草适宜液肥配方的初步研究

为加速矮生沿阶草的繁殖和推广,通过N、P、K 3因素不同配比施肥,研究不同NPK的配合施用对矮生沿阶草生长的影响。综合叶片生长速率、出叶速率、叶绿素含量、单位时间内新根发生数量、根系活力等测定结果认为,NPK适当配比才能促进其正常生长,处理N2P2K1、N2P2K2能较好地调节矮生沿阶草地上、地下生物量分配,促进植株快速生长。适宜矮生沿阶草生长的专用肥配方为N、P2O5、K2O按照7:3:（8~8.5）配比。     

猪肉中四环素类抗生素的固相萃取-液相色谱法测定

本文建立了猪肉中四环素类抗生素的高灵敏度测定方法,通过对实验条件的优化,采用固相萃取- 反相高效色谱法同时测定猪肉中的土霉素（oxytertracycline ）, 四环素（tetracycline ）,金霉素（chlorteracycline ）,去甲基金霉素（demeclocycline ）,脱氧土霉素（doxycycline） 五种抗生素残留量;土霉素,四环素,金霉素,脱氧土霉素, 去甲基金霉素的检出限分别为50,50,100, 100, 50ug/kg,方法相对标准偏差范围为3.7 %-8.9 % (n = 5) 平均回收率70 %-90 %。 关键词 ：固相萃取;反相高效液相色谱法;四环素类;猪肉     

鹿蹄草内生真菌生物学特性研究

内生真菌对鹿蹄草的生长、抗逆等具有重要意义。笔者对1株鹿蹄草内生真菌R25（Nectria sp.）的生物学特性进行报道,旨在为该菌株在鹿蹄草等园林绿化植物引种驯化中的应用提供依据。研究发现：R25在培养的1～2天生长缓慢,3～10天生长迅速,11天后生长趋于稳定。该菌的适宜生长温度为10～25℃,最适生长温度为20℃;在pH 4.0～8.0之间均能生长,最适生长pH为5.0～6.0;在各光照条件下均能生长,但黑暗对生长更有利;该菌株能利用多种碳、氮源,其中最适碳、氮源分别为葡萄糖、硝酸钾,且在OMA培养基中产孢能力最强。     

Nitrogen Accumulation and Translocation for Winter Wheat under Different Irrigation Regimes

The translocation of pre‐anthesis nitrogen to the grain is an important source for winter wheat. The relation between the nitrogen translocation and irrigation regime was studied in the field under a rain‐proof trough shelter. Nitrogen (N) translocation amount, N translocation efficiency decreased with a decline in irrigation amount or by excessive irrigation. Compared with different organs, the leaf and stem had higher N translocation amounts, and contributions to grain for both cultivars – Jinan 17 and Lumai 21, indicating that stem also is a major N source for grain development. The contribution of pre‐anthesis total above ground N to grain N ranged from 57 to 76 %, indicating the importance of pre‐anthesis storage of N for achieving high grain N concentrations. Grain nitrogen and yield (kg ha^?1) were positively and significantly correlated with the N translocation amounts and contributions, respectively, suggesting that the sink strength may be involved in the translocation of N from a vegetative organ to the grain. N harvest index (NHI) was significantly correlated with N translocation efficiency, suggesting that the latter is a prerequisite for increasing grain N and improving grain quality. The experiment showed that N translocation status is enhanced by better irrigation practices, but limited by severely deficient or excessive irrigation.     

Corporate Dividend Policy Under the Change of Earnings in China

Using non-parameter test and multinomial logit regression, this paper studies the dividend policy and behavior empirically. The results show that the change of the earnings of firms affects their dividend policy. When the EPS of the firms increase, the probability of choosing not to pay cash dividend is maximal, yet when the EPS of the firms decrease, many firms choose not to pay cash dividend or choose to increase DPS, so that the information that the relevant firms have great expectation is transmitted to the market. Furthermore, this paper also finds that the successiveness of the dividend policy of the listed firms in China is not good.     

基于SSR分子标记的闽楠(Phoebe bournei)核心种质的构建

为更好地发掘和利用现有闽楠种质资源,本研究利用7个SSR位点对江西和福建16个闽楠群体的237份材料进行基因型分析,采用逐步聚类(随机取样策略,位点优先取样策略)和模拟退火算法(等位基因数目最大化策略,遗传距离最大化策略)4种取样方法构建闽楠核心种质,并将各遗传多样性指标进行分析。结果表明:7个SSR位点共检测到50个等位基因,平均为7.143,平均有效等位基因为2.115,Shannon信息指数为0.778,观测杂合度为0.302,期望杂合度为0.442。基于逐步聚类方法构建的核心种质相较于基于模拟退火算法构建的核心种质各遗传参数指标都相对较高。对其进行t检验后,选择以基于逐步聚类位点优先取样策略在25%的取样比例下选取的种质为核心种质,其等位基因数、平均有效等位基因数、多态性位点百分率、Shannon多样性指数的保留率分别为初始种质的98%、104.92%、90.09%、97.94%。筛选出的59份核心种质材料能够较好地代表闽楠种质资源的遗传多样性,为闽楠的种质资源保存提供科学依据。     

繁缕(Stellaria media(L.)Vill.)种子萌发特性的研究

对繁缕进行温度、光照、低温贮藏、赤霉素和破种皮处理实验,研究不同条件对种子萌发的影响。结果表明,繁缕种子萌发对温度敏感,对光照不敏感,最适宜的萌发温度为12℃,最适光照条件为8 h。低温贮藏处理可有效促进种子萌发,-70℃贮藏后种子萌发率达到93.25%。赤霉素对种子萌芽影响较显著,最适浓度为500 mg/L。破种皮处理后种子萌发效果最好,萌发率达到96.75%,并于5 d萌发完毕。