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[目的]确定污泥最佳絮凝剂种类及其最佳的投加量和脱水工艺参数。[方法]针对石化企业污泥脱水工艺中存在的问题,以污泥沉降性能、污泥比阻和滤饼含水率为指标筛选出最佳絮凝剂,并通过正交试验对污泥脱水工艺进行优化。[结果]各因素对滤饼含水率的影响顺序为：搅拌水平〉投加量〉抽滤压力〉絮凝剂。最佳操作条件为絮凝剂K6728投加量2．0ml;搅拌水平150r／min 10s,50r／min 10min：过滤压力0．05MPa。各因素对污泥比阻的影响顺序为：搅拌水平〉抽滤压力〉投加量〉絮凝剂。最佳操作条件为絮凝剂K6728投加量2．5ml;搅拌水平150r／min 10s,50r／min 10min;过滤压力0．03MPa。综合分析得出最佳工艺参数为：K6728絮凝剂投加量2．0ml;搅拌水平150r／min 10s,50r／min 10min;过滤压力0．03MPa。此时,污泥脱水效果最佳。[结论]优化了石化污泥脱水工艺。 相似文献
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In cultures of mouse adrenocortical tumor cells (Sato's minimal deviation Y-1 clonal strain), the acceleration of steroid biosynthesis after exposure to adrenocorticotropic hormone or cyclic adenosine 3',5'-monophosphate is maximum within 15 to 60 minutes and precedes any significant increase in labeling of protein with [4,5-(3)H]leucine. However, when cytosol proteins are separated by acrylamidegel electrophoresis, rapid changes in the amount and labeling of several protein fractions are evident in less than 30 minutes and are no longer evident within 60 minutes. This finding supports the proposal that the effects of tropic hormones and their intracellular mediators involve rapid selective effects on protein synthesis. 相似文献
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Acylation of proteins with myristic acid occurs cotranslationally 总被引：36，自引：0，他引：36
Several proteins of viral and cellular origin are acylated with myristic acid early during their biogenesis. To investigate the possibility that myristylation occurred cotranslationally, the BC3H1 muscle cell line, which contains a broad array of myristylated proteins, was pulse-labeled with [3H]myristic acid. Nascent polypeptide chains covalently associated with transfer RNA were isolated subsequently by ion-exchange chromatography. [3H]Myristate was attached to nascent chains through an amide linkage and was identified by thin-layer chromatography after its release from nascent chains by acid methanolysis. Inhibition of cellular protein synthesis with puromycin resulted in cessation of [3H]myristate-labeling of nascent chains, in agreement with the dependence of this modification on protein synthesis in vivo. These data represent a direct demonstration that myristylation of proteins is a cotranslational modification. 相似文献
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采用常规合成法制备了杂多酸H5PV2Mo10O40,并通过FT-IR、XRD、SEM对其进行表征。研究了[BMIM]Cl单催化与{H5PV2Mo10O40+[BMIM]Cl}双效催化体系中,反应时间、温度以及H5PV2Mo10O40用量对麦草碱木质素降解的影响,并初步探讨了木质素的降解机理。结果表明:H5PV2Mo10O40中P、V、Mo相对原子质量满足1:2:10关系,并具有典型的Keggin结构;木质素降解反应中,仅离子液体[BMIM]Cl降解木质素的最佳条件为140 ℃下反应3 h,降解后固体产物中总羟基由3.49 mol/kg增加到10.92 mol/kg,液体产物中有香草醛与丁香醛生成,分别占2.00%和2.15%;{H5PV2Mo10O40+[BMIM]Cl}双效催化体系中,最佳反应条件为加入20%的H5PV2Mo10O40 120 ℃下反应6 h,降解后固体产物中总羟基由3.49 mol/kg增加到14.12 mol/kg,摩尔质量由7.691 kg/mol降为1.589 kg/mol;液体产物中无丁香醛生成,香草醛占6.97%。初步认为:当单独[BMIM]Cl催化木质素时,H+首先进攻木质素中β-O-4键上的氧原子,正电荷转移到β位,然后水分子中氧原子向带有正电荷的β位进攻,从而催化剂的H+被消除,最后实现了β-O-4键水解断裂,生成愈创木酚,进而侧链发生氧化生成香草醛与丁香醛;当添加H5PV2Mo10O40时,[PV2Mo10O40]5-中的VO2+由V(V)→V(IV),故使模型化合物得以单电子的氧化,使木质素脱甲氧基,由紫丁香基木质素转变成愈创木基木质素,液体产物中无丁香醛生成,且香草醛质量分数升高。 相似文献
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Methylation increases sodium transport into A6 apical membrane vesicles: possible mode of aldosterone action 总被引：7，自引：0，他引：7
S Sariban-Sohraby M Burg W P Wiesmann P K Chiang J P Johnson 《Science (New York, N.Y.)》1984,225(4663):745-746
When isolated apical membrane vesicles prepared from cultured A6 epithelia were incubated in vitro with the methyl donor S-adenosylmethionine, the control rate of amiloride-inhibitable sodium transport was doubled. The methylation inhibitors 3-deazaadenosine and S-adenosyl homocysteine returned the S-adenosyl-methionine-stimulated sodium transport to control levels. Neither these agents nor adenosine affected sodium transport into control vesicles. In vesicles incubated with S-adenosyl-[3H-methyl]methionine, both membrane phospholipids and proteins were labeled, and this labeling was inhibited by deazaadenosine. In vesicles prepared from A6 cells treated with aldosterone, sodium transport was twice the control value and S-adenosylmethionine did not cause any further stimulation of transport. In those vesicles, both lipid and protein methylation were increased. These results suggest that methylation, which increases the rate of amiloride-sensitive sodium transport is involved in the action of aldosterone at the apical membrane level in epithelia. 相似文献
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[目的]优化黄秋葵果胶提取工艺。[方法]采用微波辅助酸解法从黄秋葵中提取果胶,以果胶得率为指标,通过考察酸的类型、酸解pH、微波时间、料液比等影响因素,确定黄秋葵果胶最佳提取工艺。[结果]试验得出,微波辅助酸解法提取黄秋葵果胶的最佳工艺条件为:硫酸、酸解pH为3、微波时间5 min、料液比1∶20 g/ml,在此条件下黄秋葵果胶的提取率为13.89%。[结论]以微波辅助酸解法获得的黄秋葵果胶品质符合国家标准,果胶提取率高,具有较好的经济效益和社会效益。 相似文献
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不同月份杜仲叶中绿原酸含量的研究 总被引：2，自引：1，他引：1
[目的]测定与比较不同月份杜仲叶中绿原酸的含量。[方法]用浓度30%甲醇回流40 min,采用反相液相色谱法测定杜仲叶中绿原酸含量。色谱柱为Kromasil C18柱,流动相为甲醇-0.02%磷酸溶液(体积比22∶78),波长327 nm,流速1.0 ml/min。绿原酸在9.78~238.00μg/L时呈良好线性关系,r为0.999 8,回收率为97.9%。[结果]通过对10年树龄的光皮杜仲树叶4~12月绿原酸含量的分析,叶中含量平均为2.55%,6月达到最高。[结论]该法快速、简单、准确。 相似文献
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The effect of GTPase activating protein upon ras is inhibited by mitogenically responsive lipids 总被引：28，自引：0，他引：28
Bacterially synthesized c-Ha-ras protein (Ras) was incubated with guanosine triphosphatase (GTPase) activating (GA) protein in the presence of various phospholipids. The stimulation of Ras GTPase activity by GA protein was inhibited in some cases. Among the lipids most active in blocking GA protein activity were lipids that show altered metabolism during mitogenic stimulation. These included phosphatidic acid (containing arachidonic acid), phosphatidylinositol phosphates, and arachidonic acid. Other lipids, including phosphatidic acid with long, saturated side chains, diacylglycerols, and many other common phospholipids, were unable to alter GA protein activity. The interaction of lipids with GA protein might be important in the regulation of Ras activity during mitogenic stimulation. 相似文献
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[目的]采用NaHCO3催化微波辐射法合成乙酰水杨酸。[方法]以水杨酸和乙酸酐为原料,碳酸氢钠作催化剂、采用微波辐射法合成乙酰水杨酸,通过单因素试验考察催化剂用量、微波功率、辐射时间对乙酰水杨酸产率的影响,并通过正交试验确定最佳工艺条件。[结果]优选出的最佳反应条件为:取6.3 g水杨酸和9 ml乙酸酐时,催化剂碳酸氢钠用量0.7 g,微波辐射功率400 W,辐射时间80 s。在此条件下,乙酰水杨酸产率达76.38%。[结论]该研究为乙酸水杨酸的合成提供了一种新的工艺。 相似文献
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[目的]探讨合成2-氨基-4-甲氧基苯甲酸的新方法。[方法]选用对甲苯胺为起始原料,采用硝化、重氮化、甲基化、氧化、选择性还原的方法来合成2-氨基-4-甲氧基苯甲酸,并对中间产物和终产物的^1H NMR、^13C NMR、IR和MS进行鉴定。[结果]试验得到6.12 g白色粉末状终产物,熔点176178℃,产率为61%,经^1H NMR、^13C NMR、IR和MS鉴定为2-氨基-4-甲氧基苯甲酸。[结论]该合成方法具有合成路线短、原料易得和总生产成本低的优点。 相似文献
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目的：研究低氧条件下的冲刺训练对运动员身体内葡萄糖、胰岛素、游离脂肪酸以及乳酸应激条件下的影响。方法：所有运动员都分别参加三组不同实验条件的训练,并且每组训练相隔7天。三组不同训练条件分别为：常氧压的冲刺运动（N组）;中等缺氧的冲刺运动（M组）;高度缺氧的冲刺运动(H组)。每组冲刺运动都在功率自行车上进行,每组运动为4次为时30s的冲刺运动,阻力都为10档,并辅以教练口头激励,每次冲刺运动后恢复6min,并记录每次运动员产生的最高功率以及平均功率。两种不同的低氧条件由低氧面具提供。训练后,分别在运动前抽取血液1次,以及在4次运动完成后5min,30min,60min,120min各取一次,并检测各项指标。结果：1.常氧压组与两组低氧压组相比,血细胞中的葡萄糖含量没有明显的差异,但是,与没有进入运动开始前相比较,冲刺运动后的5min内葡萄糖含量上升显著。2.只有在冲刺运动完成后2h后,体内脂肪酸含量才显著上升,并且与常氧压组和中等低氧压组相比较,高度缺氧组的游离脂肪酸上升更为明显,且与这两组差异显著。3.与运动开始前相比,运动后5min、30min、60min内体内乳酸含量高,且具有显著差异。但在120min后差异消失。4.运动结束后5min时体内胰岛素含量较高,且与开始运动前和运动结束后其他三个时间段相比,具有显著差异。 相似文献
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Autoradiographic imaging of phosphoinositide turnover in the brain 总被引：10，自引：0，他引：10
With [3H]cytidine as a precursor, phosphoinositide turnover can be localized in brain slices by selective autoradiography of the product [3H]cytidine diphosphate diacylglycerol, which is membrane-bound. In the cerebellum, glutamatergic stimulation elicits an increase of phosphoinositide turnover only in Purkinje cells and the molecular layer. In the hippocampus, both glutamatergic and muscarinic cholinergic stimulation increase phosphoinositide turnover, but with distinct localizations. Cholinergic stimulation affects CA1, CA3, CA4, and subiculum, whereas glutamatergic effects are restricted to the subiculum and CA3. Imaging phosphoinositide turnover in brain slices, which are amenable to electrophysiologic studies, will permit a dynamic localized analysis of regulation of this second messenger in response to synaptic stimulation of specific neuronal pathways. 相似文献
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[目的]探索以蔗糖溶液作为介质分离纯化隐孢子虫卵囊的最佳条件。[方法]以隐孢子虫感染阳性奶牛粪样为材料,设计5个蔗糖浓度、3个离心时间和3个离心速度进行隐孢子虫卵裳的分离纯化。[结果]蔗糖浓度为1：2．0和1：2．5时,分离出的卵囊总数极显著大于其他3组（P〈0．01）,其中1：2．5组卵囊平均数最大;不同离心时间分离出的卵囊总数在数量上差异均不显著（P〉0．05）,其中离心20min时卵囊平均数最大;不同离心速度分离出的卵囊总数的比较表明,3000r／min得到的卵囊数量最多。[结论]蔗糖浓度为1：2．5、离心速度为3000r／min、离心时间为20min是隐孢子虫卵囊分离纯化的最佳条件。 相似文献
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[目的]利用马铃薯残渣为原料合成乳酸预聚物,为聚乳酸的生产工艺改造提供理论依据。[方法]将由马铃薯残渣发酵所得的乳酸采用熔融缩聚法合成乳酸预聚物,并对此方法进行了优化。[结果]最佳工艺：催化剂辛酸亚锡的用量1%,熔融缩聚时间10 h,反应温度170℃,1,4-丁二醇用量1%。[结论]熔融缩聚法聚合所得的聚乳酸预聚物的最高分子量为3059 g/mol,用马铃薯残渣为原料合成乳酸预聚物简单易行,该方法提供了一种新的废物利用途径。 相似文献
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[目的]为提高棉花产量、品质,研究黄腐酸钾的最佳用量。[方法]采用大田随机区组定位试验,设置6个处理,CK:不施肥,F:单施化肥750 kg/hm~2,F+H1:化肥750 kg/hm~2配施黄腐酸钾75 kg/hm~2,F+H2:化肥750 kg/hm~2配施黄腐酸钾150 kg/hm~2,F+H3:化肥750 kg/hm~2配施黄腐酸钾300 kg/hm~2,F+H4:化肥750 kg/hm~2配施黄腐酸钾450 kg/hm~2,定位4年后测定棉花株高、果枝数、成铃数、单铃重、衣分、籽棉产量、纤维品质等指标。[结果]化肥与黄腐酸钾配施能促进棉花后期的营养生长与生殖生长,随着黄腐酸钾用量增加秋桃数与秋桃比例呈增加趋势;单株铃数、籽棉产量、皮棉产量呈随黄腐酸钾用量增加而增加的趋势,4个配施黄腐酸钾处理较单施化肥处理籽棉产量分别提高3.3%、5.4%、5.2%与9.0%;配施黄腐酸钾提高了棉花纤维品质,尤其是对纺纱均匀性指数有显著提升作用。[结论]化肥配合施用黄腐酸钾450 kg/hm~2,可有效提高棉花产量,改善棉花纤维品质。 相似文献
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Nelson CD Perry SJ Regier DS Prescott SM Topham MK Lefkowitz RJ 《Science (New York, N.Y.)》2007,315(5812):663-666
Seven-transmembrane receptor (7TMR) signaling is transduced by second messengers such as diacylglycerol (DAG) generated in response to the heterotrimeric guanine nucleotide-binding protein Gq and is terminated by receptor desensitization and degradation of the second messengers. We show that beta-arrestins coordinate both processes for the Gq-coupled M1 muscarinic receptor. beta-Arrestins physically interact with diacylglycerol kinases (DGKs), enzymes that degrade DAG. Moreover, beta-arrestins are essential for conversion of DAG to phosphatidic acid after agonist stimulation, and this activity requires recruitment of the beta-arrestin-DGK complex to activated 7TMRs. The dual function of beta-arrestins, limiting production of diacylglycerol (by receptor desensitization) while enhancing its rate of degradation, is analogous to their ability to recruit adenosine 3',5'-monophosphate phosphodiesterases to Gs-coupled beta2-adrenergic receptors. Thus, beta-arrestins can serve similar regulatory functions for disparate classes of 7TMRs through structurally dissimilar enzymes that degrade chemically distinct second messengers. 相似文献
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[目的]分析叶面喷施蚯蚓氨基酸液肥对黄瓜品质的影响,为蚯蚓氨基酸肥在蔬菜上推广应用提供参考依据.[方法]设H1(喷施0.3%KH2PO4)、H2(喷施蚯蚓氨基酸800倍液+0.3%KH2PO4)、H3(喷施蚯蚓氨基酸500倍液+0.3%KH2PO4)、H4(喷施蚯蚓氨基酸300倍液+0.3%KH2PO4)、H5(喷施蚯蚓氨基酸800倍液)、H6(喷施蚯蚓氨基酸500倍液)、H7(喷施蚯蚓氨基酸300倍液)及清水对照(CK)处理,在黄瓜挂果期进行叶面喷施,采收时测定各处理黄瓜果实的维生素C(Vc)、蛋白质、可溶性还原糖、有机酸、硝酸盐含量及糖酸比.[结果]与CK相比,采收时H2、H3和H6处理黄瓜的Vc含量分别显著增加40.0%、53.5%和38.0%(P<0.05,下同);H2、H3、H4、H6和H7处理的硝酸盐含量显著降低55.2%、85.3%、67.5%、31.6%和49.6%;H3处理的蛋白质含量显著增加31.2%;各施肥处理的可溶性还原糖含量均降低,其中H4、H5和H6处理显著低于CK;H2和H3处理的有机酸含量分别显著降低14.2%和22.8%,H5、H6和H7处理分别显著降低39.1%、44.8%和36.8%;分别与H5、H6和H7处理相比,H2、H3和H4处理黄瓜的Vc含量增加,糖酸比降低,有机酸含量较高且差异显著,硝酸盐含量显著降低60.8%、78.5%和35.5%.[结论]在黄瓜挂果期喷施适当浓度的蚯蚓氨基酸液肥有利于整体提升黄瓜果实品质,其中喷施蚯蚓氨基酸500倍+0.3%KH2PO4混合液的效果最佳. 相似文献