农业专业镇中小微企业服务平台发展战略初探——以广东省为例

农业专业镇是广东省农村经济发展的重要推动力。如今农业专业镇的发展面临着结构调整、产业升级和增长方式转变的巨大挑战，服务平台发展的战略选择对农业专业镇发展至关重要。专业镇的中小微企业服务平台建设发展呈现出以创新为核心、产学研紧密结合的趋势：加快中小微企业服务平台发展，在战略上必须以政府为主导，市场化配合运作，将载体建设与功能培育协同运作，将产学研合作与联盟服务协同运作，将品牌建设与重点扶持紧密结合，形成协同运作体系网。     

基于动态平衡视角下现代足球阵型演变的沿革与变迁

拟在动态平衡的视角下对现代足球阵型的演变历程进行梳理与整合，希望对阵型之间的关联及其对足球运动发展的影响提供见解，对阵型演变的不同阶段进行探讨，探寻足球攻守平衡与不同阵型的嬗变关系，同时也为推动未来足球阵型演变对战术打法的影响研究提供参考依据。采用文献资料、系统分析、专家访谈和逻辑分析等方法，对现有的足球阵型发展的概况进行分析之后，认为现代足球阵型的演变历程不断交替出现攻守的平衡与不平衡，正是交替出现的状况促进了阵型的改变，进而影响了阵型的发展。当阵型的发展过程中出现攻守平衡时，就有其它后来者对该阵型进行学习、模仿、改进、提高。当阵型的发展过程中出现攻守不平衡，攻强于守或者守强于攻时，就会促进阵型的演变向攻守平衡的方向发展，因此就会出现阵型的发展处于不平衡-平衡-不平衡-再到平衡的态势，从而形成比赛阵型发展本身的稳定与不稳定状态交替出现。研究认为，世界足球阵型演变的过程是一种动态的、不断发展的、维持某种平衡与稳定的、平衡和不平衡交替运动的情况，即动态平衡的状态。提出将现代足球阵型演变的过程分为不同的阶段，每一个阶段内，都分别出现攻守平衡与攻守不平衡的状态，而这种平衡与不平衡的存在与区别、斗争与转化正是足球阵型演变与发展的规律。     

Chronic hypoxia enhances aggressiveness of MCF-7 breast cancer cells through EMT

AIM: To investigate the effects of chronic hypoxia on the aggressiveness of MCF-7, a human breast cancer cell line, and the underlying mechanisms.METHODS: MCF-7 cells were cultured under hypoxia (1% O₂, 5% CO₂ and 94% N₂) or control (95% O₂ and 5% CO₂) condition. The viability, proliferation, and invasion and migration abilities of the MCF-7 cells were determined by MTT assay, CCK-8 assay, cell counting, and cell invasion and migration assays. Anchorage-independent growth and the alteration of cellular polarization of the MCF-7 cells were tested by soft agar colony formation assay and Matrigel-3D culture assay, respectively. The effects of chronic hypoxia on the growth and metastasis of MCF-7 cells in vivo were investigated by xenograft in nude mice. The morphological changes of the MCF-7 cells were observed under an inverted microscope. Hypoxia-induced alterations in the levels of hypoxia inducible factor-1 (HIF-1) and phosphorylated glycogen synthase kinase-3β (p-GSK-3β) as well as epithelial-mesenchymal transition (EMT) molecules, such as E-cadherin, N-cadherin, vimentin, matrix metalloproteinase (MMP)-3 and MMP-9, were determined by Western blot.RESULTS: Chronic hypoxia significantly increased the viability, proliferation, and invasion and migration abilities of MCF-7 cells in vitro, enhanced the anchorage-independent growth, facilitated cellular polarization alteration in Matrigel-3D culture, and promoted cancer metastasis in vivo. Hypoxia up-regulated HIF-1, activated GSK-3β, down-regulated E-cadherin and increased the protein levels of N-cadherin, vimentin, MMP-3 and MMP-9. CONCLUSION: Chronic hypoxia enhances the aggressiveness of breast cancer cells probably through EMT.     

GMP玻璃化冷冻未成熟牛卵母细胞核成熟及冷冻损伤试验

本试验通过荧光染色的方法建立了未成熟牛卵母细胞在体外培养过程中第1次减数分裂的各个阶段的参考判定图谱;根据这个标准来观察毛细玻璃管(GMP)玻璃化冷冻对卵母细胞核成熟和冷冻损伤的影响。结果表明,从屠宰场废弃的卵巢表面卵泡内抽取的COCs,70%处于生发泡期,12.5%生发泡开始破裂,7.5%已开始浓缩,这说明从屠宰场获得的COCs有较高的异质性;卵母细胞在成熟培养22h时收获排出第一极体的卵母细胞,可得到丰度较高的极体-胞质染色体对称、紧密相邻的成熟卵母细胞;GMP玻璃化冷冻损伤主要有2种表现形式,首先,直接影响膜结构的完整性,包括细胞膜和核膜,这可从退化的细胞比例看出(8～24h,有21.9%～27.2%的细胞处于该阶段),其次,影响CONDENSED向MⅠ期的过渡,这可从处于CONDENSED卵母细胞的比例看出(8～24h,有24.1%～34.3%的细胞处于该阶段)。     

Low potassium diets with different levels of calcium in comparison with different anionic diets fed to prepartum dairy cows: Effects on sorting behaviour,total tract digestibility,energy metabolism,oxidative status and hormonal response

This study investigated the effects of low potassium diets with different levels of Ca compared to two diets low in dietary cation–anion difference (DCAD) fed prepartum as a strategy to prevent hypocalcemia on sorting behaviour, total tract digestibility, oxidative status and energy and protein metabolism of transition cows. Forty-eight pregnant dairy cows were assigned to 4 treatment groups: Low Ca, low K (LCLK), High Ca, low K (HCLK), Supplementation with anionic mineral mixture (AMS) supplementation with SoyChlor (CAS). After parturition, all animals were fed a standard postpartum diet. Data were collected until 21 DIM. Prepartum urinary pH was significantly reduced by the low DCAD diets, while postpartum Ca homeostasis was affected by the HCLK ration. Feeding AMS induced sorting against particles <1.18 mm in favour of particles >19 mm prepartum. In contrast, cows fed CAS showed an increase in selective consumption of fine particles and sorted against longer particles similar to the HCLK and LCLK groups. Postpartum sorting activity was not affected by the dietary treatments. After calving, apparent digestibility of NDF was significantly reduced in the HCLK group. Prepartum, we observed effects on serum concentrations of non-esterified fatty acids were higher and insulin sensitivity was lower in the AMS group. Blood urea nitrogen (BUN) was decreased in cows fed the CAS ration. Postpartum, we found serum protein to be decreased with the low DCAD diets while BUN was decreased in the CAS group. The low DCAD rations increased prepartum serum malondialdehyde concentrations, while postpartum total antioxidant capacity was lower in the HCLK and the AMS group. From these data, we conclude that AMS decreased prepartum intake due to compromised palatability. Intermediate protein metabolism was affected by the low DCAD diets, while parameters of oxidative stress were probably affected by acid–base balance and Ca homeostasis.     

电车接触网腕臂的计算

电气化铁道的“三大元件”分为接触网、电力机车和牵引变电所。本论文论述时速200Km/h高速电气化铁路的接触网电车接触网腕臂的计算,接触网的计算精确程度就关系到接触线悬挂的可靠程度,故接触网计算是设计中基础的工作内容,其计算主要分为腕臂的计算和接触网的负载计算。文章详细分析了腕臂长度的计算方法,重点介绍了路基曲线区段腕臂长度、转换柱和中心柱腕臂长度的计算。     

Association of oxidative status and insulin sensitivity in periparturient dairy cattle: an observational study

Post‐parturient insulin resistance (IR) is a common feature in all mammalian animals. However, in dairy cows, it can be exacerbated because of high milk yield, leading to excessive negative energy balance, which is related with increased disease incidence, reduced milk production and worsened reproductive performance. IR has been extensively investigated in humans suffering from diabetes mellitus. In these subjects, it is known that oxidative stress (OS) plays a causative role in the onset of IR. Although OS occurs in transitional dairy cattle, there are yet no studies that investigated the association between IR and OS in dairy cattle. Therefore, the aim of this study was to investigate whether there is a relationship between OS and IR in dairy cattle. Serum samples were taken repeatedly from 22 dairy cows from 2 months prior to the expected calving date to 2 months after calving and were analysed for markers of metabolic and redox balance. Surrogate indices of insulin sensitivity were also calculated. Generalised linear mixed models revealed an effect of the oxidative status on peripheral insulin concentration and on indices of insulin sensitivity. Hence, field trials should investigate the effectiveness of antioxidant therapy on insulin sensitivity in peripheral tissues during the transition period of dairy cattle.     

粮食生产的机械化问题

粮食牛产机械化是生产力发展的一个重要方而，也是一种必然趋势。机械化生产手段可以提高粮食产量，确保粮食生产持续发展，提高粮食生产效率和经济效益。粮食生产机械化不仅是农业技术变迁的一种自然发展过程，而且与制度变迁密切相关、互相促进。在粮食生产机械化中，有很多现实问题需要解决。