共查询到20条相似文献，搜索用时 281 毫秒
1.
在课外活动中,我们指导学生着手CCl_4的回收的实验。 首先,我们就想到,由于CCl_4这种有机溶剂的沸点较低(比碘的沸点低)可以用蒸馏的方法来达到分离的目的。 相似文献
2.
《中学生数理化(高中版)》2017,(7)
<正>钠及其化合物在中学化学学习中具有非常重要作用,掌握钠及其化合物的主要性质对以后的学习至关重要,下面举例说明。一、钠的性质例1(1)钠能否保存在CCl4中?(2)金属钠露置在空气中会发生什么样的变化,最终生成什么物质?答:(1)不能,CCl_4的密度太大了,Na在 相似文献
3.
lmol 与足量 NaOH 溶液反应,消耗 NaOH 的物质的量为:A 3mol B 4mol C 3nmol D 4nmol解析解答本题应把握三点:该药物属于高聚物;该物质中含有3处酯键可水解;酯键水解得到的酸类物质能继续与 NaOH 发生中和反应,则 lmol 该物质消耗4nmolNaOH,故选 D。例2.向2mL0.5mol/L 的 FeCl_3溶液中加入3mL5mol/L 的 KF 溶液,发现 FeCl_3溶液渐渐褪至无色,再加入 KI 溶液和 CCl_4振荡后,静置,不见 CCl_4层有紫红色,则下列说法正确的是:A Fe~(3+)不与 I~-发生反应 B Fe~3+)与 F~-结合成不与 I~-反应的物质 C F~-使I~-的还原性减弱 D Fe~(3+)被 F~-还原为 Fe~(2+),使溶液中不再存在 Fe~(3+)解析向 FeCl_3溶液中加入足量 KF 溶液后得到无色溶液,说明该溶液中不存在或含极少量的 Fe~(3+)(黄色)、Fe~(2+)(浅绿色),则排除 D 选项;往所得溶液中再加入 KI 溶液和 CCl_4振荡后静置,不见 CCl_4层有紫红 相似文献
4.
1986年化学高考试题中有这样一道题:有一瓶澄清的溶液,其中可能含有 NH_4~+、K~+、Na~+、MgO~(2+)、Ba~(2+)、Al~(3+)、Fe~(3+)、SO_4~(2-)、CO_3~(2-)、NO_3~-Cl~-和 I~-。取该溶液进行如下实验:(1)用 pH 试纸试验,表明溶液呈强酸性:(2)取部分溶液,加入少量 CCl_4及数滴新制氯水,经摇荡后 CCl_4层呈紫红色;……。根据以上实验事实确定:在该溶液中肯定存在的离子是_____,肯定不存在的离子是_____,还不能确定是否存在的离子是_____。 相似文献
5.
在中学课本中常见共价分子类型有:A_2型(如Cl_2、H_2);AB型(如HCl、HBr);AB_2型(如H_2S、CO_2);AB_3型(如NH_3、PCl_3);AB_4型(如CCl_4、CH_4);AB_5型(如PCl_5、PF_5)。 相似文献
6.
一般萃取液的回收只考虑了四氯化碳,且尚有不足之处,笔者经过反复实验,摸索到一种简易的回收方法,现介绍如下: 一、实验步骤 1.往萃取液中逐滴滴入25—40％NaOH溶液,同时充分搅拌(或振荡),这时溶于CCl_4的I_2跟NaOH发生歧化反应: 相似文献
7.
《实验室研究与探索》2013,(10):304-307
在拉曼光谱检测中,样品池的选择至关重要,尤其对于信号较弱的样品,基底干扰的排除是开展检测工作的第一步。目的:系统比较若干实验室常见样品池的拉曼吸收,避免来自背景的干扰。方法:对"拉曼谱仪载物台、玻璃载玻片、玻璃毛细管、云母片、铝箔、石英片、不锈钢片"等若干样品池分别在532、633和785 nm进行拉曼光谱检测。实验结果显示:①铝箔、石英片和不锈钢片在各波长下均显示出较好的无干扰特性,其他样品池拉曼吸收明显;②对于拉曼信号较强的样品(例如CCl_4),仍可选择本身存在拉曼吸收的样品池,例如玻璃毛细管。 相似文献
8.
一、仪器装配: 取一标好体积刻度的中型试管,在试管中倒进汞适量,将其放入已盛有CCl_4的圆底烧瓶。另取细玻管一支,通过单孔塞,将其下端浸入汞内将整个装配好的园底烧并与水浴设备装配。 相似文献
9.
10.
关于气体定律,在高一化学教材《摩尔》一章中提出气体摩尔体积和阿佛加德罗定律,然后在该书第五章的一个习题中,作为提示,提出了气体方程的简单形式(P_1V_1/T_1)=(P_2V_2/T_2);此后在实验教材“CCl_4分子量的测定”中,提出了PV=nRT,然而对其运用仅涉及分子量的计算,课文中一直未提及用相对密度法计算气态物质的分子量。我们应结合物理教学和化学作业,以理想气体状态方程PV=nRT为核心,系统地进行气体定律应用于化学计算 相似文献
11.
目的:观察脂肪肝大鼠在生化、病理、脂肪代谢、细胞因子、胰岛素及瘦素各方面指标的变化.方法:雄性Wistar大鼠22只,按体重层次随机分为2组,对照组(A)11只,脂肪肝组(B)11只.对照组饲以普通鼠饲料,脂肪肝组饲以高脂饲料.8周后,全部处死,取血及肝组织,测定血中AIT、AST、TG、CHO、INS、FBS、FFA、Ieptin、II-6、TNF.肝组织匀浆测定肝组织TC,TG,SOD、MDA,观察肝脏组织学变化.结果:脂肪肝大鼠存在明显脂肪代谢紊乱,肝功能异常,胰岛素抵抗及瘦素表达增高;细胞因子升高.结论:实验性高脂饮食脂肪肝大鼠存在瘦素抵抗及胰岛素抵抗. 相似文献
12.
Research on the protection effect of pioglitazone for non-alcoholic fatty liver disease （NAFLD） in rats 总被引：4，自引：0，他引：4
Objective： The prevalence of non-alcoholic fatty liver disease （NAFLD） has markedly increased. Insulin resistance has been implicated in the pathogenesis of NAFLD. This study was aimed at observing the relationship between insulin resistance and NAFLD, and evaluating the role of pioglitazone （PGZ） acting as insulin-sensitizing agents in the prevention and treatment of rat fatty liver induced by high fat feeding. Methods： The rats were separated randomly into 6 groups： model group Ⅰ were fed high fat diet for 8 weeks, PGZ prevention group were given PGZ 4 mg/（kg.d） simultaneously, while control group Ⅰ were fed normal food for 8 weeks; model group Ⅱ were fed high fat diet for 16 weeks, PGZ treatment group were given PGZ 4 mg/（kg.d） orally simultaneous with high fat diet for 8 weeks after high fat feeding for 8 weeks, control group Ⅱ were fed normal food for 16 weeks. The rats were sacrificed after 8 weeks and 16 weeks respectively. Liver weight, body weight, serum activities of alanine aminotransferase （ALT）, aspartate aminotransferase （AST）, alkaline phosphatase （ALP）, tumor necrosis factor alpha （TNF-α）, fasting blood glucose （FBG）, fasting plasma insulin （FINS）, HOMA （homeostasis model assessment） insulin resistance index （HOMA-IR）, and the liver histology of rats of all groups were assayed. Results： After 8 weeks, the liver in model group Ⅰ showed typical steatosis, accompanied with mild to moderate lobular inflammatory cell infiltration, liver indexes and serum levels of ALT, AST, ALP, TNF-α were significantly increased （P〈0.05） compared with control group Ⅰ. Whereas, the degree of hepatic injury was attenuated in PGZ prevention group, liver indexes and serum levels of ALT, ALP were significantly decreased （P〈0.05） compared with model group Ⅰ. After 16 weeks, notable steatosis, and lobular inflammation were observed in model group Ⅱ rat liver, while the degree of hepatic injury was attenuated in the PGZ treatment group. Liver index, serum levels ofALT, AST, ALP, FINS and HOMA-IR were significantly increased （P〈0.05） in model group Ⅱ compared with control group Ⅱ. Whereas, in PGZ treatment group, serum levels of AST and FINS showed decreasing tendency, liver indexes, serum levels of ALT, ALP, TNF-α and HOMA-IR were significantly decreased compared with model group Ⅱ. Conclusion： Insulin resistance plays a role in the pathogenesis of NAFLD in rats. Pioglitazone can attenuate insulin resistance and biochemical and histological injury in high fat-induced fatty liver in rats. 相似文献
13.
Belemtougri RG Constantin B Cognard C Raymond G Sawadogo L 《Journal of Zhejiang University. Science. B》2006,7(1):56-63
Crude decoction, aqueous and ethanolic extracts of two medicinal plants （Psidiura guajava and Diospyros raespiliformis）, widely used in the central plateau of Burkina Faso to treat many diseases were evaluated for their antagonistic effects on caffeine induced calcium release from sarcoplasmic reticulum of rat skeletal muscle cells. These different extracts showed a decrease of caffeine induced calcium release in a dose dependent manner. Comparison of the results showed that Psidiura guajava leaf extracts are more active than extracts of Diospyros mespiliformis and that crude decoctions show better inhibitory activity. The observed results could explaine their use as antihypertensive and antidiarrhoeal agents in traditional medicine, by inhibiting intracellular calcium release. 相似文献
14.
Chun Pang Yu-chen Sheng Ping Jiang Hai Wei Li-li Ji 《Journal of Zhejiang University. Science. B》2015,16(7):602-610
Chlorogenic acid (CGA), a polyphenolic compound, is abundant in fruits, dietary vegetables, and some medicinal herbs. This study investigated the prevention of CGA against acetaminophen (AP)-induced hepatotoxicity and its engaged mechanisms. CGA reversed the decreased cell viability induced by AP in L-02 cells in vitro. In addition, CGA reduced the AP-induced increased serum levels of alanine/aspartate aminotransferase (ALT/AST) in vivo. The effect of CGA on cytochrome P450 (CYP) enzymatic (CYP2E1, CYP1A2, and CYP3A4) activities showed that CGA caused very little inhibition on CYP2E1 and CYP1A2 enzymatic activities, but not CYP3A4. The measurement of liver malondialdehyde (MDA), reactive oxygen species (ROS), and glutathione (GSH) levels showed that CGA prevented AP-induced liver oxidative stress injury. Further, CGA increased the AP-induced decreased mRNA expression of peroxiredoxin (Prx) 1, 2, 3, 5, 6, epoxide hydrolase (Ephx) 2, and polymerase (RNA) II (DNA directed) polypeptide K (Polr2k), and nuclear factor erythroid-2-related factor 2 (Nrf2). In summary, CGA ameliorates the AP-induced liver injury probably by slightly inhibiting CYP2E1 and CYP1A2 enzymatic properties. In addition, cellular important antioxidant signals such as Prx1, 2, 3, 5, 6, Ephx2, Polr2k, and Nrf2 also contributed to the protection of CGA against AP-induced oxidative stress injury. 相似文献
15.
刘静 《陕西教育学院学报》2012,(3):87-89
为了研究杜仲叶提取物对力竭运动及恢复小鼠的抗疲劳作用,选取72只ICR小鼠随机分为安静对照组A、安静杜仲叶提取物组B、力竭运动对照组C、力竭运动杜仲叶提取物组D、力竭运动恢复对照组E和力竭运动恢复杜仲叶提取物组F,每组12只,各给药组小鼠每日按1.5g生药/kg体重剂量以杜仲叶提取物灌胃,各对照组小鼠以蒸馏水灌胃,连续30d后,将C组、D组、E组和F组小鼠置于水中游泳至力竭,记录力竭运动时间。C组和D组小鼠运动后即刻取肝脏、心脏、股四头肌备用。A组和B组不做运动处理,直接取肝脏、心脏、股四头肌备用。E组和F组小鼠恢复24h后取肝脏、心脏、股四头肌备用。测定小鼠肝脏、心脏、股四头肌SOD、POD活性和MDA含量。显示杜仲叶提取物可以提高力竭运动及恢复状态下小鼠肝脏、心脏、股四头肌中SOD、POD活性,减少MDA生成。表明杜仲叶提取物对力竭运动及恢复小鼠有抗疲劳作用。 相似文献
16.
17.
探索了将较为成熟的科研成果"文蛤酶解产物防醉解酒"的科研实验设计转化成药理学综合教学实验。以工艺成熟的文蛤酶解产物为评价对象,采用白酒灌胃的方式建立小鼠中剂量饮酒模型,疲劳转棒仪评价文蛤酶解产物对饮酒造成的小鼠平衡失调的缓减作用;建立高剂量饮酒模型,以翻正实验观察文蛤酶解产物的防醉解酒效果,同时测定血液及肝组织相关生化指标,光学显微镜下观察小鼠肝脏组织病理学变化。该实验可帮助学生巩固实验动物的捉、拿、固定、灌胃等基本操作,掌握醉酒模型评价实验的一般思路与方法,促进学生掌握生化分析、病理学切片等综合实验技能,提高分析数据及团队协作能力,符合国家对创新性人才的培养需求。 相似文献
18.
Xia-zhen Yu Tao Ji Xue-li Bai Liang Liang Lin-yan Wang Wei Chen Ting-bo Liang 《Journal of Zhejiang University. Science. B》2013,14(1):68-75
Background and objective:Hepatic sinusoidal obstruction syndrome(HSOS) is characterized by painful hepatomegaly,ascites,increased body weight,and jaundice.Gynura segetum(Compositae),a plant widely used in Chinese traditional medicine,often leads to the development of HSOS.However,the mechanism is unclear.The aim was to study the role of matrix metalloproteinase-9(MMP-9) in the onset of HSOS induced by Gynura segetum.Methods:Twenty-five male Sprague-Dawley rats were randomly divided into two groups.Twenty were exposed to 600 mg/kg daily Gynura segetum extract solution for three weeks;five control rats were exposed to tap water alone.Liver sections were evaluated by light microscopy with a modified scoring system.Routine transmission electron microscopy(TEM) methods were used to evaluate the ultrastructual features of fixed liver tissue,and blood samples were collected to determine liver enzyme concentrations.MMP-9 expression was assessed by both immunohistochemical staining and enzyme-linked immunosorbent assay(ELISA) methods.Results:A stable and reproducible rat model of HSOS was achieved by long-term exposure to Gynura segetum extract.The treated rats presented clinical symptoms and the histopathological manifestation of HSOS,including abnormal liver enzyme concentrations(alanine aminotransferase(ALT):(84.8±13.62) vs.(167.0±72.63) U/L,P<0.05;aspartate aminotransferase(AST):(27.6±6.31) vs.(232.8±108.58) U/L,P<0.05).Hematoxylin and eosin(H&E) staining and TEM together revealed deposition of red blood cells,the damage and destruction of hepatic sinusoidal endothelial cells,collapse of hepatic sinusoids,hemorrhage of subendothelial cells,atrophy and destruction of hepatocytes,etc.Compared with controls,the expression of MMP-9 in the blood sample,the lung and liver tissues of HSOS rats was increased.Conclusions:MMP-9 may have an important role in early pathological changes of HSOS,and thus the onset of the disease. 相似文献
19.
目的:观察一枝黄花提取液对大鼠实验性胃溃疡的影响,探讨一枝黄花抗消化性溃疡作用。方法:分别建立应激性、药物性、手术性多种溃疡模型,以一枝黄花提取液灌胃,进行溃疡干预实验,并观察一枝黄花提取液对幽门螺杆菌的影响。结果:一枝黄花提取液可明显降低各种溃疡模型的溃疡指数,幽门螺杆菌对其敏感。结论:一枝黄花具有抗消化性溃疡作用,可进一步研究利用。 相似文献
20.
Evaluation of the hepatoprotective and antioxidant activities of Rubus parvifolius L 总被引：1，自引：0，他引：1
Gao J Sun CR Yang JH Shi JM Du YG Zhang YY Li JH Wan HT 《Journal of Zhejiang University. Science. B》2011,12(2):135-142
The hepatoprotective and antioxidant activities of the n-butanol extract of Rubus parvifolius L. (RPL), a widely used medicinal plant, were evaluated. Results demonstrated that RPL extract possessed pronounced hepatoprotective
effects against carbon tetrachloride (CCl4)-induced hepatic injury in mice, which was at least partially attributed to its strong antioxidant capacity. Treatment with
RPL extract markedly attenuated the increases in serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST)
levels caused by CCl4 intoxication. It also significantly prevented the decrease in superoxide dismutase (SOD) activity and the increase in malondialdehyde
(MDA) content of liver tissue. Meanwhile, histopathological changes of hepatic damage were also remarkably ameliorated. Phytochemical
analysis based on high-performance liquid chromatography/tandem mass spectrometry (HPLC-MS/MS) revealed the presence of various
phenolic compounds, including caffeic acid conjugates, ellagic acid glycosides, and flavonol glycosides, which might be responsible
for the hepatoprotective and antioxidant activities of RPL. 相似文献