首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   19篇
  免费   0篇
  2022年   1篇
  2021年   1篇
  2020年   1篇
  2019年   2篇
  2018年   1篇
  2015年   1篇
  2014年   2篇
  2013年   1篇
  2012年   1篇
  2011年   2篇
  2010年   1篇
  2007年   1篇
  1997年   1篇
  1996年   1篇
  1995年   1篇
  1989年   1篇
排序方式: 共有19条查询结果,搜索用时 15 毫秒
1.
The action of the coumarin-type drugs and related compounds is reviewed to their VKOR antagonistic effects. In our study, twenty 3-pyridinyl, pyrimidinyl and pyrazolyl-4-hydroxycoumarin derivatives were synthesized. A comparative in vivo (CT, PT determination) and in vitro (measurement of PIVKA-II levels) anticoagulant study with respect to warfarin showed that the synthesized compounds have different anticoagulant activities, the most prospective compounds were the 3-pyrazolyl-4-hydroxycoumarin derivatives.  相似文献   
2.
3.
Salivary gland duct ligation is an alternative to gland excision for treating sialorrhea or reducing salivary gland size prior to tumor excision. Duct ligation also is used as an approach to study salivary gland aging, regeneration, radiotherapy, sialolithiasis and sialadenitis. Reports conflict about the contribution of each salivary cell population to gland size reduction after ductal ligation. Certain cell populations, especially acini, reportedly undergo atrophy, apoptosis and proliferation during reduction of gland size. Acini also have been reported to de-differentiate into ducts. These contradictory results have been attributed to different animal or salivary gland models, or to methods of ligation. We report here a bilateral double ligature technique for rabbit parotid glands with histologic observations at 1, 7, 14, 30, 60 days after ligation. A large battery of special stains and immunohistochemical procedures was employed to define the cell populations. Four stages with overlapping features were observed that led to progressive shutdown of gland activities: 1) marked atrophy of the acinar cells occurred by 14 days, 2) response to and removal of the secretory material trapped in the acinar and ductal lumens mainly between 30 and 60 days, 3) reduction in the number of parenchymal (mostly acinar) cells by apoptosis that occurred mainly between 14–30 days, and 4) maintenance of steady-state at 60 days with a low rate of fluid, protein, and glycoprotein secretion, which greatly decreased the number of leukocytes engaged in the removal of the luminal contents. The main post- ligation characteristics were dilation of ductal and acinar lumens, massive transient infiltration of mostly heterophils (rabbit polymorphonuclear leukocytes), acinar atrophy, and apoptosis of both acinar and ductal cells. Proliferation was uncommon except in the larger ducts. By 30 days, the distribution of myoepithelial cells had spread from exclusively investing the intercalated ducts pre-ligation to surrounding a majority of the residual duct-like structures, many of which clearly were atrophic acini. Thus, both atrophy and apoptosis made major contributions to the post-ligation reduction in gland size. Structures also occurred with both ductal and acinar markers that suggested acini differentiating into ducts. Overall, the reaction to duct ligation proceeded at a considerably slower pace in the rabbit parotid glands than has been reported for the salivary glands of the rat.  相似文献   
4.
An indirect ELISA was developed and initially evaluated for the detection of bovine antibodies to Leptospira interrogans serovar pomona. The antigen used in this ELISA was extracted from a serovar pomona culture supernatant by a combination of centrifugation, digestion with proteinase K and ultra-centrifugation. The antigen showed little cross-reaction with immune rabbit sera to L. interrogans serovars copenhageni, grippotyphosa, hardjo and sejroe and, Leptospira biflexa serovar patoc. Some cross-reaction was observed with immune rabbit serum to L. interrogans serovar canicola. The relative sensitivity of the ELISA was 94.76% confidence interval =± 3.32%) when estimated with bovine sera (n=172) with serovar pomona microscopic agglutination test (MAT) titers of 100. The relative specificity of the ELISA was 99.28% (95% confidence interval = 1.40%) when estimated with bovine sera (n=139) with MAT titers of <100 to L. interrogans serovars canicola, copenhageni, grippotyphosa, hardjo, pomona and sejroe. Thirty six of 258 field sera (13.95%) with serovar pomona MAT titers of <100, gave positive reactions in the ELISA.  相似文献   
5.
An enzyme-linked immunofiltration assay (ELIFA) and a microtitre plate enzyme-linked immunosorbent assay (ELISA) were developed and compared for their ability to detect staphylococcal enterotoxin B (SEB). The double antibody capture format was used for both assays. Factors which improved the sensitivity of the ELIFA system were (1) addition of casein and thimerosal to the antigen dilution buffer; (2) addition of polyethylene glycol (MW 6000) to the detection and conjugate antibody dilution buffers; and (3) washing with diethanolamine buffer prior to addition of the substrate/chromogen. The ELIFA system had a turnaround time of approximately 1 h and a detection limit of 1 ng/mL of purified SEB. The ELISA had a total turnaround time of 21 h, or 3 h using plates pre-coated overnight with the capture antibody. The detection limit of the ELISA for purified SEB was 0.05 ng/mL. The detection limit of SEB in cheese samples spiked with purified enterotoxin and subjected to a simple extraction procedure was 1 ng/mL and 0.1 ng/mL of extract, with the ELIFA and the ELISA, respectively.  相似文献   
6.
Two new series of furochromone and benzofuran derivatives were designed, synthesized and evaluated for their in vitro anticancer activity against MCF-7 and MDA231 breast cancer cell lines. Compounds 5, 6, 7, 9, 15a, 16, 17a and 18 exhibited the best antiproliferative activities with IC50 values ranging from 1.19 to 2.78?µM against MCF-7 superior to lapatinib as reference standard (IC50; 4.69?µM). Compounds 15a and 18 revealed significant cytotoxic activity against MCF-7 and MDA231, therefore their inhibitory potencies against p38α MAP kinase were evaluated. Remarkably they exhibited significant IC50 of 0.04?µM comparable to SB203580 (IC50; 0.50?µM) as a reference standard. These promising results of cytotoxic activity and significant inhibition of p38α MAP kinase, were confirmed by exploring the effect of benzofuran derivative (18) on the apoptotic induction and cell cycle progression of MCF-7 cell line. Compound 18 induced preG1 apoptosis and cell growth arrest at G2/M phase preventing the mitotic cycle. Moreover it activated the caspase-7 which executes apoptosis. Molecular docking study was carried out using GOLD program to predict the mode of binding interaction of the synthesized compounds into the target p38α MAPK. Additionally, the physicochemical properties and ADME parameters of compound 18 were examined in silico to investigate its drug-likeness.  相似文献   
7.
Soil contamination with heavy metals is one of the main environmental concerns in China, mainly owing to rapid industrialization and mining activities in certain areas. The current study aimed at monitoring the levels of heavy metals in soils of the industrial areas along the Jinxi River and surrounding Lake Qingshan. In addition, a health risk assessment for humans in contact with these soils was also conducted. The results revealed that the soils of the studied areas were contaminated with Cr, Cu, As, Se, Cd, Pb, and Zn and that the industrial activities were the main source of soil contamination therein. Furthermore, soils of the sites adjacent to Lin’an city exhibited higher levels of heavy metals than the upstream and Lake Qingshan sites. Most of the studied heavy metals tended to concentrate in the fine soil fractions (PM100, PM10, and PM2.5). Calculation of the hazard index (HI) revealed that humans, especially children, have potential health risks. Moreover, As was found to contribute to more magnitude of cancer risks. Thus, we concluded that the unmanaged development negatively affects the Chinese environment and human health. Furthermore, fine fractions of soil particles should be considered for risk assessment.  相似文献   
8.
China's rapid industrialization and mining activities have led to rigorous deterioration in the quality of soil and water. This study aimed at evaluating the environmental impacts of industrial activities around the Jinxi River using geochemical and statistical methods. To attain this aim, water and sediment samples were collected from 14 sites along the Jinxi River and around Lake Qingshan, and analyzed for their concentrations of heavy metals using ICP-mass. The results show that the concentrations of studied heavy metals didn't exceed the maximum permissible limits (MPL) in water, except for Fe and Cu. For sediment analysis, according to sediment quality guidelines (SQGs), the studied sediment samples varied from non-polluted to heavy rate for Cr, Ni, Cu, As, Mn, Zn, and Fe and non-polluted for Cd and Pb. In addition, the sites adjacent to Lina’n City were significantly enriched with Cr, Cu, Cd, and Zn and extremely enriched with As and Se. Principal component analysis (PCA) and correlation analyses revealed that an anthropogenic source was the main source for heavy metals in the river system. We concluded that geochemical and statistical analyses can provide useful information for water quality assessment. Furthermore, the Chinese government should formulate strict laws to prevent the water streams from contamination.  相似文献   
9.
Elevated concentrations of salts in soil and water represent abiotic stresses. It considerably restricts plant productivity. However, the use of alpha-tocopherol (α-toc) as foliar can overcome this problem. It can improve crop productivity grown under salinity stress. Limited literature is documented regarding its optimum foliar application on sunflower. That’s why the need for the time is to optimize α-toc foliar application rates for sunflower cultivated in salt-affected soil. A pot experiment was performed to select a better α-toc foliar application for mitigation of salt stress in different sunflower cultivars FH (572 and 621). There were 2 levels of salts, i.e., control (no salt stress) and sodium chloride (120 mM) and four α-toc foliar application (0, 100, 200, and 300 mg L−1). Results showed that foliar application of 100 mg/L- α-toc triggered the remarkable increase in fresh shoot weight, fresh root weight, shoot, and root lengths under salinity stress in FH-572 and FH-621 over 0 mg/L- α-toc. Foliar application of 200 mg/L- α-toc was most effective for improvement in chlorophyll a, chlorophyll b, total chlorophyll and carotenoids compared to 0 mg/L- α-toc. Furthermore, an increase in A was noted in FH-572 (17%) and FH-621 (22%) with α-toc (300 mg L−1) application under saline condition. In conclusion, the 100 and 200 mg/L- α-toc are the best application rates for the improvement in sunflower FH-572 and FH-621 growth, chlorophyll contents and gas exchange attributes. Further investigations are needed to select a better foliar application rate between 100 and 200 mg/L- α-toc at the field level under the different agro-climatic zone and soil types.  相似文献   
10.
Herein, we report the synthesis of different novel sets of coumarin-6-sulfonamide derivatives bearing different functionalities (4a, b, 8a–d, 11a–d, 13a, b, and 15a–c), and in vitro evaluation of their growth inhibitory activity towards the proliferation of three cancer cell lines; HepG2 (hepatocellular carcinoma), MCF-7 (breast cancer), and Caco-2 (colon cancer). HepG2 cells were the most sensitive cells to the influence of the target coumarins. Compounds 13a and 15a emerged as the most active members against HepG2 cells (IC50?=?3.48?±?0.28 and 5.03?±?0.39?µM, respectively). Compounds 13a and 15a were able to induce apoptosis in HepG2 cells, as assured by the upregulation of the Bax and downregulation of the Bcl-2, besides boosting caspase-3 levels. Besides, compound 13a induced a significant increase in the percentage of cells at Pre-G1 by 6.4-folds, with concurrent significant arrest in the G2-M phase by 5.4-folds compared to control. Also, 13a displayed significant increase in the percentage of annexin V-FITC positive apoptotic cells from 1.75–13.76%. Moreover, QSAR models were established to explore the structural requirements controlling the anti-proliferative activities.  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