首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 187 毫秒
1.
雪茄产业是近年来中国烟草行业新的经济增长点,雪茄烟种植中根结线虫病危害严重.然而,目前国内外雪茄烟病原线虫的种类尚未明确,对该病害的绿色防控也鲜有报道.基于雌虫、雄虫和二龄幼虫的形态特征、PCR扩增特异性条带及科赫法则验证结果,将普洱市江城县雪茄烟叶“云雪1号”品种上发生的根结线虫病病原鉴定为爪哇根结线虫(Meloidogyne javanica).评估了4种食用菌(金针菇、杏鲍菇、香菇、姬菇)菌渣脲酶催化尿素释放氨气熏蒸土壤对雪茄烟叶爪哇根结线虫病的防治效果.结果表明:致死100%二龄幼虫(J2)所需的NH3最低质量浓度为136.8 mg/m3;将含4%尿素的4种菌渣分别与土壤按质量比为1∶18的比例混合,在水分含量约60%、28℃下放置3 d时,各处理组释放的氨气质量浓度在130.9~218.7 mg/m3,对根结线虫病的防效在75.7%~92.3%.研究结果显示“菌渣+尿素”熏蒸土壤对防控雪茄烟根结线虫病具有很好的应用潜力.  相似文献   

2.
SAM合成酶基因的克隆及在酿酒酵母中的高效表达   总被引:2,自引:0,他引:2  
采用PCR技术从S.cerevisiae TCCC 31012菌株的染色体DNA中扩增得到S-腺苷甲硫氨酸合成酶-2基因(sam2),将sam2克隆到酿酒酵母表达载体pACT2的强启动子PADHI控制下,以构建高效表达质粒,并在酿酒酵母亮氨酸缺陷型茵株YS58中表达.重组质粒经鉴定含有sam2基因.工程菌YS58-2表达产物经SDS-PAGE,结果显示重组菌S-腺苷甲硫氨酸合成酶的分子质量约为43ku,经凝胶电泳扫描,表达带约占菌体总蛋白的14%.YS58-2菌株培养72 h的SAM合成酶活力为16.5 U/mg茵体蛋白,较出发菌S.cerevisiae TCCC 31012提高了40.3倍,较受体菌YS58提高了32倍.  相似文献   

3.
以正己醛为载体、以氧化环糊精为内相捕捉剂制备一种新的乳状液膜,运用其清除分离尿素,旨在研究一种治疗尿毒症或缓解症状的新型疗法.实验发现,当外相尿素溶液浓度为13g/L,载体正己醛含量为5%,内相氧化环糊精浓度为15%,内相pH=10时。乳状液膜吸附容量为24.7mg/g.内相氧化环糊精的浓度对单位吸附量起决定作用,但是对吸附速率影响不大.内相pH值由于能直接影响内相捕捉剂与尿素结合物的稳定性,所以对单位吸附量有重要影响.此种吸附剂对氨基酸吸附量仅为尿素的1/10,这为其在含大量氨基酸的人体环境中有效清除尿素提供了优良的选择性,避免了其他尿毒症吸附剂普遍存在的吸附选择性低的缺点.  相似文献   

4.
大肠杆菌葡萄糖脱氢酶基因的克隆与原核表达   总被引:1,自引:0,他引:1  
克隆出大肠杆菌编码葡萄糖脱氢酶(PQQGDH)的 gcd 基因,构建了诱导型表达载体pET28a-gcd,转化大肠杆菌E. coli BL21后获得阳性克隆菌株BL21/pET28a-gcd。IPTG诱导后,经SDS-PAGE分析表明,该工程菌PQQGDH的表达量约为对照菌的18倍,约为18.2 mg/L,实现了高表达。此外,研究发现添加MgCl2能提高PQQGDH的表达量。  相似文献   

5.
利用SBR反应器,探讨了不同溶解氧(DO)浓度和污泥浓度条件下,游离氨(FA)对晚期垃圾渗滤短程硝化过程的影响.试验结果发现,当DO浓度从0.5 mg/L增加到0.75 mg/L时,最大氨氧化速率有较大的增加,且较高的亚硝酸菌活性可以减弱FA对其的抑制作用,FA对硝酸菌的抑制浓度约为4.2~8.1 mg/L;限制DO实现短程硝化比控制FA更为稳定;污泥浓度也是短程硝化的重要影响因素之一,当DO浓度控制在0.75 mg/L时,较佳的污泥浓度约为6 800~8 100 mg/L.此时亚硝酸菌活性较强,且由于FA在污泥絮体内的扩散限制,亚硝酸菌可"适应"更高的FA浓度.图5,表2,参10.  相似文献   

6.
红霉素菌渣生物改性研究   总被引:1,自引:0,他引:1  
以白地霉、地衣芽胞杆菌、假丝酵母、乳酸菌、光合菌制备的复合微生物菌剂,以红霉素菌渣为主要原料,进行固态发酵.结果表明,红霉素菌渣:棉籽饼粉为8∶2、硫酸铵0.4%、尿素0.2%、磷酸二氢钾0.3%、硫酸镁0.1%,原料∶水1∶1,接种量10%,32℃,培养周期为4 d.经发酵后的红霉素菌渣去除了特殊异味和药分残留,改变了红霉素菌渣的生物化学特性,其蛋白质含量达到39.43%.经改性的红霉素菌渣可代替部分黄豆饼粉用于红霉素的发酵生产,是优质的蛋白饲料资源.  相似文献   

7.
对落叶松根朽病病根进行分离培养.结果表明:引起根朽病的病原菌为奥氏蜜环菌Armillaria ostoyae,其菌索为最佳分离源,组织分离和子实体分离不易成功;病原菌在综合马铃薯汁培养基上生长良好,3 d后长出白色后变黑褐色菌落,5~6 d后长出菌索.病原菌的3个菌株生长的最适合温度为25℃;最适pH为6.0~6.4;最佳碳源为葡萄糖、麦芽糖;最佳氮源为尿素和酵母粉,在KNO3和(NH4)2HPO4等无机氮源上生长不良.室内药剂敏感性测定结果表明:使用5.00 mg/mL硫酸铜、1.25 mg/mL70%代森锰锌、1.25 mg/mL5%百菌清可以有效防治根朽病.室内病原菌与拮抗真菌的对峙结果表明,所用的厚环乳牛肝菌Suillus grevillei等6种菌根菌和2种工程菌对病原菌A5.92都有抑制作用.其中厚环乳牛肝菌Suillus grevillei、赭丝膜菌Cortinarius russus、红蜡蘑Laccarialaccata抑制作用最强,不仅产生最明显的抑菌环,抑制病原菌的生长,同时覆盖病原菌并在其上生长,可用于根朽病的生物防治.  相似文献   

8.
为大规模制备rhBMP-2m,将高表达rhBMP-2m的工程菌株进行高密度发酵、温度诱导表达,收集菌体,经裂菌和超声洗涤得到并纯化的包涵体。洗涤后的包涵体中,rhBMP-2mdi蛋白量的75.1%。为获得高纯度的rhBMP-2m,采用尿素作变性剂将包涵体溶解,经SP-SepharoseFF柱和Q-SepharoseFF柱两步纯化。rhBMP-2m包涵体经pH6.5尿素溶解后,经SP-Sepharose FF柱纯化,蛋白纯度为91%;若rhBMP-2m在碱性尿素中作用时间超过48h,再经Q-SepharoseFF柱纯化后,纯化产物中在还原性SDS-PAGE中会出现少量与rhBMP-2m二聚体大小接近的蛋白带,显示出碱性尿素对rhBMP-2m的共价修饰作用,会严重地影响rhBMP-2m的纯化效果和活性;若24h内完成分离纯化则影响较小,纯化后rhBMP-2m单体的纯度达98%以上。本研究表明尿素适合rhBMP-2m包涵体的大规模纯化。文章对使用尿素的利弊进行了讨论,提出大规模制备蛋白质时最好避免在碱性环境使用高浓度尿素。  相似文献   

9.
从活性污泥中分离出一株好氧耐盐反硝化菌YFX-6,耐盐度10%.经生理生化鉴定和16S rDNA测序,鉴定出菌株YFX-6属于Halomonas sp.考察了不同C/N质量浓度比、溶解氧、接种量、处理时间对菌株YFX-6在粮果实际废水中反硝化脱氮效果的研究.随着C/N质量浓度比的不断增加,菌株YFX-6的反硝化脱氮效果先逐渐增强后又减弱;随着溶解氧、处理时间和接种量的不断增加,菌株YFX-6的脱氮效果逐渐增强后趋于稳定.初始硝态氮质量浓度约为108.5 mg/L,氯化钠质量浓度为10 mg/L,C/N质量浓度比为8,溶解氧为3.5 mg/L,接种量所占体积分数为20%,处理16 h时,硝态氮去除率为98.69%.因此,筛选出的一株好养耐盐的异氧反硝化菌可以在上述条件下表现出良好的脱氮性能.  相似文献   

10.
目的研究降酚菌的降解影响因素,诱变选育出高效苯酚降解菌,并确定此株高效菌的降解特性.方法从3种土样中分离纯化出一株能降解较高质量浓度苯酚的野生菌P4,通过菌落形态及显微镜观察作初步鉴定.采用紫外诱变的方法,从诱变后的正突变菌株中选取一株降解率最高且生长旺盛的菌株,命名为高效苯酚降解菌P4S,利用正交试验法测试其降解特性.结果初步鉴定野生菌株P4为酵母菌,该菌能在48 h内将800 mg/L的苯酚完全降解.经紫外诱变选育出的高效降酚菌P4S,能降解1 600 mg/L的苯酚,并可耐受1 700 mg/L的苯酚.由正交试验与验证性试验结果相比较,得出其在苯酚废水中的最佳降解条件为150 r/min,36℃,pH为6,生物投加量为5%,降解率可达85%.结论经诱变选育出的高效苯酚降解菌能降解更高质量浓度的苯酚,环境适应范围更广,更适用于实际生产.  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

15.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

16.
Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.  相似文献   

17.
以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.  相似文献   

18.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

19.
Quality traits in wheat (Triticum aestirum L.) were studied by quantitative trait locus (QTL) analysis in a recombinant inbred line (RIL) population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross (ChSh). Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.  相似文献   

20.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号