排序方式： 共有82条查询结果，搜索用时 703 毫秒
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用ＰＳＵ／ＮＣＡＲ中尺度数值模式,对１９９５年６月２３至２４日的一次大暴雨过程进行了模拟试验．结果表明,潜热的反馈及地形的强迫对降雨量起决定性的作用,潜热对降雨量的增幅达８０％,地形为６８％,其中盆地北侧山脉起绝大部分的作用,盆地南侧的武夷山、仙霞岭对金衢盆地降水量的影响很小,而对其东面洞宫山脉一带的雨量有很大的影响． 相似文献
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西兰花是中国典型的出口兼内销蔬菜品种。毒死蜱、辛硫磷和茚虫威是中国蔬菜生产中的常用农药。通过田间试验，对比这3种农药在露地和温室栽培模式下，按照推荐剂量和1.5倍推荐剂量用药，在西兰花花球、叶片和土壤中的残留动态。样品采用QuEChERS方法处理和液相色谱-质谱（LC-MS/MS）多残留检测。验证结果表明：在质量比分别为0.02、0.2和1 mg/kg时，毒死蜱、辛硫磷和茚虫威的添加回收率分别为85.8%~101.0%、90.8%~105.3%和86.1%~107.5%。3种农药的最低检出限（LOD）为0.006 mg/kg，最低定量限（LOQ）为0.01 mg/kg，满足方法要求。残留动态结果表明：在西兰花花球上，毒死蜱的半衰期为5.53~7.20 d，辛硫磷为3.55~3.92 d，茚虫威为6.11~7.73 d；在西兰花叶片上，毒死蜱的半衰期为4.33~6.93 d，辛硫磷为3.85~5.77 d，茚虫威为3.85~5.33 d；在土壤中，毒死蜱的半衰期为23.1~34.6 d，辛硫磷为23.1~34.6 d，茚虫威为17.3~23.1 d。最终残留对比表明，3种农药在西兰花叶片的残留量高于花蕾的残留量。在试验剂量施用量条件下，茚虫威和毒死蜱的限量标准不会超过现有欧盟、日本、CAC标准；在高剂量使用条件下，辛硫磷会出现超标现象。 相似文献
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研究目的：评价毒死蜱施用后对土壤细菌和真菌群落结构的影响,并对降解功能菌株进行分析。创新要点：通过聚合酶链式反应–变性梯度凝胶电泳（PCR-DGGE）方法,揭示了毒死蜱施用后土壤细菌和真菌群落结构动态变化,并对试验土壤中的降解菌群进行分子鉴定。研究方法：将农田土壤用终质量分数5 mg/kg和20 mg/kg毒死蜱处理,同时以不施用毒死蜱为对照,定期采集土样进行毒死蜱残留测定并提取土壤DNA。将提取的土壤总DNA作为PCR反应模板,细菌群落结构分析采用对大多数细菌16S rRNA基因V3区具有特异性的引物GC-341F和517R,真菌群落结构分析采用ITS区特异引物对GC-ITS1f和ITS2f。DGGE图谱经Quantity One软件进行数字化分析,各泳道中的条带经标准化处理之后,条带的相对光密度构成一个矩阵,用Matlab软件进行主成分分析（PCA）,用Dice法计算相似性指数CS,用MEGA 4.1软件构建系统发育树,进行聚类分析。之后,采用LB、察氏和高氏三种培养基结合的纯培养分离方法,从毒死蜱处理土样中分离具有降解功能的菌株。分别提取纯培养物的染色体DNA,利用ERIC-PCR对分离到的降解菌进行基因组指纹图谱分析,将典型肠杆菌基因间的重复共有序列–聚合酶链式反应（ERIC-PCR）指纹图谱类型的代表菌株进行16S rRNA基因（细菌和放线菌）或ITS区（真菌）扩增并测序,测序结果提交GenBank基因库,并进行BLAST比对,初步确定降解菌株的分子地位。重要结论：本实验条件下,毒死蜱降解符合一级动力学,5 mg/kg和20 mg/kg毒死蜱浓度下的降解方程分别为y=5.252e-0.09x和y=19.41e-0.08x。DGGE指纹图谱显示,毒死蜱施用后土壤真菌群落结构与对照相比发生很大改变,且毒死蜱处理样品真菌群落结构保持基本稳定,多样性指数明显提高（见图2b）;主成分分析显示,毒死蜱处理样品与对照明显分在2个不同的区域,充分表明毒死蜱对土壤真菌群落结构影响迅速且持久（见图3b）。毒死蜱处理样品细菌群落结构只在试验前30天与对照相比明显不同,60天时已经恢复对照水平（见图2a）,同时主成分分析图上,毒死蜱处理样品与对照也越来越靠近,最后聚在一起（见图3a）,说明毒死蜱对土壤细菌群落结构影响短暂。最后,获得了9个典型的ERIC型毒死蜱降解菌株。 相似文献
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Chao LI Da-ren LIU Long-yun YE Ling-na HUANG Sanjay JAISWAL Xiao-wen LI Hou-hong WANG Li CHEN 《Journal of Zhejiang University. Science. B》2014,15(6):582-589
Objective
Numerous studies examining the relationship between human epidermal growth factor receptor 2 (HER-2) overexpression and survival in patients with colorectal cancer (CRC) have yielded controversial results. We therefore performed a meta-analysis more precisely to estimate its prognostic value.Methods
Published studies investigating the effect of HER-2 overexpression on CRC survival were identified; the hazard ratios (HRs) and their corresponding 95% confidence intervals (95% CIs) were pooled in terms of disease-specific or overall survival.Results
Eleven studies were included in the meta-analysis. The pooled data showed that HER-2 overexpression was negatively related to CRC survival (HR=1.10, 95% CI: 0.77–1.44). Subgroup analyses regarding test method and study quality also demonstrated little association between HER-2 overexpression and CRC survival (HR=0.89, 95% CI: 0.50–1.29; HR=0.90, 95% CI: 0.43–1.37, respectively).Conclusions
Regardless of several limitations, our study suggested that HER-2 overexpression probably had little impact on CRC survival. 相似文献49.
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Assignment of <Emphasis Type="Italic">CCR7</Emphasis> gene to chicken chromosome 27 by radiation hybrid panel mapping 总被引：1，自引：0，他引：1
Tian Y Lu LZ Fu Y Tao ZR Shen JD Wang DQ Yuan AP Yin ZZ 《Journal of Zhejiang University. Science. B》2007,8(5):314-317
The protein encoded by CC chemokine receptor 7 （CCR7） is a member of the G protein-coupled receptor family. This receptor was identified as a gene induced by the Epstein-Barr virus （EBV）, and is thought to be a mediator of EBV effects on B lymphocytes. This receptor is expressed in various lymphoid tissues and activates B and T lymphocytes. It has been shown to control the migration of memory T cells to inflamed tissues, as well as stimulate dendritic cell maturation. To map the CCR7 gene in chicken chromosome, a 6000 rads chicken-hamster radiation hybrid panel （ChickRH6） was used. PCR of samples from ChickRH6 revealed that the location of CCR7 gene is linked to the maker SEQ0347 （6 cR away） with LOD score of 16.6 and that the marker SEQ0347 is located on chromosome 27 at 27 cR of RH （radiation hydrid） map. We compared the corresponding human mRNA sequence with the predicted coding sequence of chicken CCR7 gene, and found that the assembled contig shared a high percentage of similarity with that of the human gene. 相似文献