初学者对冷冲压中冲裁模设计刃口尺寸计算(配做法)中容易出现的几个误区

模具工业是国民经济的重要基础工业之一。模具是工业生产中的基础工艺装备,是一种高附加值的高精密集型产品,也是高新技术产业化的重要领域,其技术水平的高低已经成为衡量一个国家制造业水平的重要标志。     

抗寒茶树品种的筛选研究

为了获得抗寒茶树品种或资源,提高茶园防冻减灾的能力,分别采用田间自然鉴定法、叶片解剖结构和电导法对24个茶树品种和优质资源的抗寒性进行了鉴定。结果表明,‘浙农113’、‘中茶102’、‘翠峰’等茶树品种在以上抗寒性鉴定方法的评价结果中均表现为较强抗寒性,属于抗寒茶树品种。不同鉴定方法评价茶树抗寒性的结果有一定的差异,综合鉴定比较的结果较单一鉴定方法的结果更可靠,更符合生产实际。     

Isolation of a Phytase-Producing Bacterial Strain from Agricultural Soil and its Characterization and Application as an Effective Eco-Friendly Phosphate Solubilizing Bioinoculant

In the present study, we isolated from agricultural soils, a Bacillus strain designated SD01N-014, expressing high-level extracellular phytase activity and investigated its potential to be used as a soil phosphate-solubilizing bioinoculant to improve soil phosphorus (P) availability and thus enhance plant growth. Soil inoculation test showed that being as an inoculant, SD01N-014 substantially enhanced soil P nutrition. Pot experiments showed that when applied to soils, SD01N-014 is capable of colonizing maize seedling roots, increasing plant-available P levels in the rhizosphere and promoting seedling growth. High tunnel trials with different vegetable plants demonstrated that SD01N-014 as a soil inoculant greatly promoted plant growth and was positively correlated with inoculum sizes. Together, these results indicate that SD01N-014 holds promising potential as a cheap, viable and eco-friendly alternative to chemical P fertilizers for increasing soil fertility and crop production in sustainable farming.     

Characteristics of canopy interception and its simulation with a revised Gash model for a larch plantation in the Liupan Mountains,China

Canopy interception is a significant proportion of incident rainfall and evapotranspiration of forest ecosystems. Hence, identifying its magnitude is vital for studies of eco-hydrological processes and hydrological impact evaluation. In this study, throughfall, stemflow and interception were measured in a pure Larix principis-rupprechtii Mayr.(larch) plantation in the Liupan Mountains of northwestern China during the growing season(May–October) of 2015, and simulated using a revised Gash model. During the study period, the total precipitation was499.0 mm; corresponding total throughfall, stemflow and canopy interception were 410.3, 2.0 and 86.7 mm,accounting for 82.2, 0.4 and 17.4% of the total precipitation, respectively. With increasing rainfall, the canopy interception ratio of individual rainfall events decreased initially and then tended to stabilize. Within the study period, the simulated total canopy interception, throughfall and stemflow were 2.2 mm lower, 2.5 mm higher and0.3 mm lower than their measured values, with a relative error of 2.5, 0.6 and 15.0%, respectively. As quantified by the model, canopy interception loss(79%) mainly consisted of interception caused by canopy adsorption, while the proportions of additional interception and trunk interception were small. The revised Gash model was highly sensitive to the parameter of canopy storage capacity,followed by the parameters of canopy density and mean rainfall intensity, but less sensitive to the parameters of mean evaporation rate, trunk storage capacity, and stemflow ratio. The revised Gash model satisfactorily simulated the total canopy interception of the larch plantation within the growing season but was less accurate for some individual rainfall events, indicating that some flaws exist in the model structure. Further measures to improve the model's ability in simulating the interception of individual rainfall events were suggested.     

村庄整治中的“小组微生”模式研究

成都市村庄整治中的"小组微生"模式在全国统筹城乡发展中独树一帜,受到多方关注并被称为"新农村建设的2.0版"。它具有先进的规划设计理念、"自民市法"的运行机制、"产村配治"的协同推进、"建改保"分类整治四大特色。该模式的实施,使得乡村形态更美丽、农民群众享福利、三产融合获发展。但从农民福利需求的角度看,存在着成本高、指标不足、轻发展等问题,需要有针对性地优化完善后加以推广应用。     

蛋氨酸三肽对奶牛乳腺上皮细胞酪蛋白和小肽转运载体基因表达量的影响

本试验旨在研究蛋氨酸三肽(Met-Met-Met)对奶牛乳腺上皮细胞(BMECs)酪蛋白和小肽转运载体基因表达量的影响。采用酶消化法培养的第3代奶牛乳腺上皮细胞为模型,各处理在培养基中分别添加0(对照)、40、50、60、70和80μg/mL的蛋氨酸三肽,每个处理5个重复,每个重复1个培养孔,分别培养细胞24、48和72h,检测奶牛乳腺上皮细胞的相对增殖率,整体试验重复2次,确定最佳培养时间;各处理在培养基中分别添加0(对照)、40、50、60、70和80μg/mL的蛋氨酸三肽,每个处理3个重复,每个重复1个培养孔,以最佳培养时间培养,用实时定量PCR法检测酪蛋白基因的表达量,确定适宜蛋氨酸三肽浓度,整体试验重复3次;以最佳培养时间和适宜蛋氨酸三肽浓度培养细胞,以未添加蛋氨酸三肽的培养基为对照,每个处理3个重复,每个重复1个培养孔,测定小肽转运载体基因的表达量,整体试验重复3次。结果表明:在培养基中添加蛋氨酸三肽培养奶牛乳腺上皮细胞24h时,相对增殖率最高;培养基中加入60μg/mL的蛋氨酸三肽培养细胞24h,αs1-酪蛋白和β-酪蛋白的基因表达量最高,同时发现奶牛乳腺上皮细胞中小肽转运载体1和小肽转运载体2基因表达量显著高于对照处理(P0.05)。综上所述,培养基中添加60μg/mL的蛋氨酸三肽能够提高奶牛乳腺上皮细胞酪蛋白和肽转运载体基因的表达量。     

基于SRAP标记的黄瓜霜霉菌遗传多样性分析

本研究对来自黑龙江、辽宁、河北、山东、江苏5个省12个黄瓜主产区的77个黄瓜霜霉菌菌株,采用SRAP分子标记进行了遗传多样性分析。从35对SRAP引物中筛选出10对引物,共产生9 554条扩增条带,其中9 132条表现多态性,占95.6%。基于SRAP分子标记,77个黄瓜霜霉菌菌株的遗传距离为0.60~1.00,表明黄瓜霜霉菌具有丰富的遗传多样性。通过聚类分析,77个黄瓜霜霉菌菌株聚类为8个类群,并且来自相同地区的菌株大多数聚集于同一类群中,表明黄瓜霜霉菌群体的遗传多样性与其地理来源密切相关。     

Study on Technology of Black Silkies Chicken Semen Freezing by DMA Pellet

The aim was to explore the effects of different kinds of dilution and thawing devices on the N,N-dimethylformamide (DMA) pellet frozen semen of Black Silkies. Firstly,the motility and fertility of the frozen semen thawed by different dilutions were compared;Then,the motility of the frozen semen was compared when the pellets were thawed using different tube and different number.Finally,the motility and fertility of the sperm thawed by three kinds of thawing devices (thermostat water bath,hotfunnel and hotplate ) were tested. The results showed that:①There was similar order of the sperm motility and fertility in the different dilution groups (LR > F > B > L),and there was significant difference among those groups (P < 0.05).②The motility was the best when the frozen semen was thawed with large thin-wall glass tube at 60℃.③The best temperature range of the 3 devices was different. The highest motility for thermostat water bath was 50 to 60℃ (0.51 to 0.59),and thermostat hotfunnel was 40 to 45℃ (0.42 to 0.46),while thermostat hotplate was 50 to 55℃ (0.61 to 0.63).There was no significant difference of the motility in the optimum temperature range for each device (P > 0.05).④The fertility of the different devices in their best thawing temperature was 26.91% (55℃,thermostat hotplate),23.08% (60℃, thermostat water bath), 20.93% (40℃, thermostat funnel),respectively,and there was no significant differences among those groups (P > 0.05).Therefore,the efficiency thawing condition for the Black Silkies frozen semen was the LR diluent,DMA cryoprotectant,pellet freezing,thawed in the thermostat hotplate at 54.9℃.     

中草药添加剂对肉鸡生产性能及营养物质代谢的影响

以艾维茵肉鸡为研究对象,共设5个试验组和1个对照组。试验组为在基础日粮中分别添加中草药添加剂方Ⅰ、方Ⅱ、方Ⅲ和加利健、杆菌肽锌两种抗生素,对照组仅饲喂基础日粮,中草药添加剂的添加水平为0.07%、0.09%、0.12%,进行为期6周的饲养试验和前后2期的代谢试验,研究中草药添加剂替代抗生素的可行性和最佳添加水平。结果表明:肉仔鸡0～3周龄和3～6周龄时加利健组各项生产指标最好,中草药添加剂中0～3周时方Ⅰ0.09%添加组的各项生产性能指标最好,3～6周时方Ⅲ0.12%添加组的各项生产性能指标最佳,但与加利健组差异不显著,说明利用中草药替代抗生素是可行的;中草药添加剂通过提高日粮代谢能、干物质代谢率和粗蛋白代谢率,增强机体对营养物质的消化和吸收,达到促进机体生长的目的。     

基于线性滤波法的单株林木抗风有限元模拟

风灾是林木发生破坏的主要原因之一,研究树木结构特征以及受力特点能够深入了解树木在受风荷载作用时各个部位的应力状态,确定其易发生破坏的区域,从而采取对应措施保证林木的安全稳定性。运用线性滤波法可以模拟实际状态下的脉动风模型;利用有限元技术可建立树木的有限元模型。结合两者可以模拟树木受动力风荷载作用的过程,并可计算树木各个部位的应力状态和位移等参数。模型搭建过程分为2个部分:风模拟,即运用线性滤波法编程计算得到随机的时程风场,再通过计算转换为脉动风荷载并施加于单株林木;树的模拟可根据单株树木各部分密度、弹性模量等与树高线性相关的假设,采用ANSYS中的参数化建模法(APDL)编程得到树木模型。最后编制宏文件,得到可以通过更改个别参数达到调节树模型以及脉动风场的命令流文件。在模型加载后,通过对所得到数据进行分析和比较,了解林木的抗风性能。在该模拟中,采用我国华北地区沿海防护林树种黑松为主要研究对象。通过模拟,了解单株黑松在脉动风荷载作用下的力学响应,得知材料的抗剪切性能决定其抗风能力大小,从而可采取相应措施如加固或对林木进行定期修剪,提升林木稳定性。