早生桑品种育151、育237的育成

采用杂交方法育成早生桑品种育151、育237,具有发芽早、产叶量高,叶质较优、抗黄化型萎缩病较强等特性,发芽期比早青桑捉早2-3天.比湖桑32号早8天左右.产叶量提高6-41%.     

抗生素对桑树外植体生长与分化的影响

试验比较了不同种类抗生素在不同浓度下对桑子叶、不定芽和新梢生长与分化的影响，结果显示：（１）培养基中卡那霉素浓度高于２０ｍｇ／Ｌ时．桑子叶不能形成不定芽；羧苄青霉素或头孢霉累大于４００ｍｇ／Ｌ时，子叶不定芽诱导率明显下降。（２）卡那霉素大于３０ｍｇ／Ｌ，羧苄青霉素或头孢霉累大于４００ｍｇ／Ｌ，不定芽抽茎受到明显抑制。（３）卡那霉素大于１０ｍｇ／Ｌ，羧苄青霉素或头孢霉素大于１００ｍｇ／Ｌ，桑树新梢难以形成根系。     

Effect of heat stress on the behavioral and physiological patterns of Small-tail Han sheep housed indoors

Tropical Animal Health and Production - This study was conducted to investigate the effects of heat stress on the behavioral and physiological patterns in Small-tail Han sheep housed indoors in...     

GAPB基因原核表达载体的构建

以拟南芥cDNA为模板,用PCR扩增出GAPB的基因全长,然后将GAPB基因片段连接到PET28a（＋）载体上,构建重组质粒并转化大肠杆菌DH5α,经菌落PCR和酶切鉴定筛选出阳性克隆,测序正确后,再将阳性克隆的质粒转化大肠杆菌BL21（DE3）。结果表明：成功构建了原核表达载体PET28a（＋）-GAPB,为后续的G...     

Mechanism of JAK2-STAT3 signaling pathway in ischemic postconditio-ning neuroprotection after cerebral ischemia in tree shrews

AIM: To investigate the regulatory effect of JAK2-STAT3 signaling pathway on the neuroprotection of ischemic postconditioning (IPoC) in tree shrews, and to explore the mechanisms of cerebral injury deterioration after inhibiting the JAK2-STAT3 pathway. METHODS: The model of thrombotic cerebral ischemia was induced by photochemical reaction in tree shrews and the IPoC was established at 4 h after ischemia followed by clipping ipsilateral common carotid artery on the ischemia side for 5 min (3 times). After IPoC and intracerebroventricular injection of AG490 (JAK2 inhibitor), the changes of cerebral infarction area were detected by TTC staining, and the histological and ultrastructural changes of cortical neurons were observed under light and electron microscopes, respectively. The protein levels of t-STAT3 and p-STAT3 in the cortical tissue were determined by Western blot. RESULTS: The neuronal pycnosis, mitochondrial swelling and vanish of the mitochondrial cristae were found in cortical cortex, and the infarction area was (24.78±3.30)% at 24 h after cerebral ischemia. Meanwhile, the phosphorylation level of STAT3 protein in the cortical tissue was significantly increased (P<0.01). The cortical neuronal damage and mitochondrial swelling were decreased after IPoC, the area of cerebral infarction was significantly reduced to (17.67±1.83)% (P<0.01), and the phosphorylation level of STAT3 protein was further increased (P<0.01). However, the neuronal damage was aggravated, the infarction area was expanded to (23.85±2.77)%(P<0.05) after treatment with AG490, and the phosphorylation level of STAT3 protein was also significantly reduced (P<0.05). CONCLUSION: IPoC may reduce cerebral injury by regulating the phosphorylation of STAT3 protein, and inhibition of JAK2-STAT3 signaling pathway may counteract the cerebral protective effect of IPoC and aggravate brain injury.     

Selection of a new scallop strain,QN‐2, from the backcross of Peruvian scallop × bay scallop F1 hybrids with bay scallops

Cross‐breeding has been successfully applied in agriculture and aquaculture industries to improve important production traits. In our previous studies, we produced the F₁ hybrids with high heterosis in growth by crossing the bay scallops with the Peruvian scallops and selected a new strain, Bohai Red, from the F₁ hybrids. In this study, we selected another new strain from the backcross (BC₁) of the F₁ hybrids with bay scallops. The base cohort (G₀) was size‐selected from the BC₁, and the G₁, G₂, G₃ and G₄ cohorts were produced with size‐selected brood stocks from the G₀, G₁, G₂ and G₃ cohorts respectively. Our results showed that average shell height, shell length, shell width and whole body weight of the G₄ cohort were increased by 16.8%, 16.8%, 11.5% and 43.6%, respectively, compared with the unselected control group of bay scallop. This new strain has now become one of the major cultured Argopecten scallops in northern China waters and was later named QN‐2.     

高丹草对波本杂羔羊的饲喂效果比较

试验选用16只波本杂F1代羔羊,按体重、性别、日龄配对分成2组,在基础饲料相同的情况下,试验组饲喂高丹草(乐食),对照组饲喂皇竹草。通过30天对比饲养试验,结果表明:试验组羔羊的平均日增重(113 g)略优于对照组(109 g),但差异不显著(P>0.05)。从而认为,高丹草饲养羔羊的效果与皇竹草相近。     

无土栽培技术的发展状况及趋势

近年来无土栽培以其优质、高产、高品质的特点,深受人们的关注.介绍了国内外无土栽培的发展状况,着重介绍了国内外无土栽培的栽培方式、自动化程度、营养液的调控和管理技术,并分析了国内无土栽培存在的问题及今后的发展方向.     

高校计算机基础教学改革的探索

计算机技术是现代信息科学技术的基础,计算机技术的发展,对高校计算机基础教育也提出了新的挑战和要求。本文就计算机基础教学的现状进行了分析和探讨,并对如何提高计算机基础的教学质量进行了深入的思考。     

筇竹与黄皮树人工混交林中筇竹地上部分生物量模型构建

本研究以筇竹与黄皮树人工混交林中筇竹地上部分为研究对象,测定分析了1~4年生分株地上部分各构件生物量及含水率,建立人工筇竹分株地上部分各构件的生物量及总生物量模型,以期为人工筇竹林的经营管理及其碳汇项目的开发提供科学依据。结果表明：随着筇竹分株年龄的增加,各构件含水率和生物量均逐渐减少,筇竹1~4年生分株地上部分平均含水率分别为57.62%、53.40%、50.01%、42.66%,平均生物量分别为133.99、123.31、109.76、85.39 g/m²;各年龄分株地上部分生物量的分配均呈现出秆＞枝＞叶的变化规律。不同年龄分株的胸径与秆、枝、叶生物量及地上部分总生物量均有极显著相关性(P＜0.01)。以胸径为自变量建立的各年龄筇竹分株地上部分总生物量模型的决定系数(R²)均在0.93以上,具有较高的可信度,也有着较强的适用性,可用于类似立地条件下的筇竹分株生物量估测。