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
教育   12篇
科学研究   4篇
综合类   3篇
  2022年   1篇
  2019年   1篇
  2015年   1篇
  2014年   2篇
  2013年   3篇
  2012年   2篇
  2011年   1篇
  2009年   1篇
  2008年   1篇
  2007年   3篇
  2005年   2篇
  2003年   1篇
排序方式: 共有19条查询结果,搜索用时 15 毫秒
1.
The bioactivity of the aqueous extracts of the leaf and stem bark of the medicinal plant, Alstonia boonei De Wild (Apocyanaceae), against the pink stalk borer, Sesamia calamistis Hampson (Lepidoptera: Noctuidae) was studied in a laboratory bioassay. The extracts were incorporated into artificial diet at a rate of 0.0% (control), 1.0%, 2.5%, 5.0%, and 10.0% (w/w). Both extracts significantly (P<0.01) reduced larval survival and weight in a dose dependent manner. The concentrations that killed 50% of the larvae (LC50) for the stem bark extract were 2.8% and 2.1% at 10 and 20 DAI (days after introduction), respectively, while those for the leaves extract were 5.6% and 3.5%. The weights of the larvae also varied significantly (P<0.05) between the treatments in a dose dependent manner. We conclude that both leaf and stem bark extracts of A. boonei are toxic, used as growth inhibitors to S. calamistis larvae, and hold good promise for use as alternative crop protectants against S. calamistis.  相似文献   
2.
Objective: The purpose of this work was to investigate the distribution pattern of fibrinolytic factors and their inhibitors in rabbit tissues. Methods: The components of the fibrinolytic system in extracts from a variety of rabbit tissues, including tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1), plasminogen (Plg), plasmin (Pl) and α2 plasmin inhibitor (α2PI), were determined by colorimetric assay. Results: The tissue extracts in renal, small intestine, lung, brain and spleen demonstrated strong fibrinolytic function, in which high activity of tPA, Plg and Pl was manifested; whereas in skeletal muscle, tongue and stomach, higher activity of PAI-1 and α2PI showed obviously. Also excellent linear correlations were found between levels of tPA and PAI-1, Pl and α2PI, Plg and Pl. In related tissues, renal cortex and renal marrow showed distinctly higher activity of tPA and lower activity of PAI-1, with the levels of Plg and Pl in renal cortex being higher than those in renal marrow, where the α2PI level was higher than that in renal cortex. Similarly, the levels of tPA, Plg and Pl in small intestine were higher than those in large intestine, but with respect to PAI-1 and α2PI, the matter was reverse. In addition, the fibrinolytic activity in muscle tissue was lower, however, the levels of tPA, Plg, and Pl in cardiac muscle were obviously higher than those in skeletal muscles, and the levels of PAI-1 and α2PI were significantly lower than those in skeletal muscle. Conclusion: Our data demonstrate that a remarkable difference of the fibrinolytic patterns exists in rabbit tissues, which has probable profound significance in understanding the relationship between the function of haemostasis or thrombosis and the physiologic function in tissues.  相似文献   
3.
Nitric oxide (NO) a free radical having both cytoprotective as well as tumor promoting agent is formed from l-arginine by converting it to l-citrulline via nitric oxide synthase enzymes. The reaction product of nitric oxide with superoxide generates potent oxidizing agent, peroxynitrite which is the main mediator of tissue and cellular injury. Peroxynitrite is reactive towards many biomolecules which includes amino acids, nucleic acid bases; metal containing compounds, etc. NO metabolites may play a key role in mediating many of the genotoxic/carcinogenic effects as DNA damage, protein or lipid modification, etc. The basic reactions of nitric oxide can be divided as direct effect of the radical where it alone plays a role in either damaging or protecting the cell milieu and an indirect effect in which the byproducts of nitric oxide formed by convergence of two independent radical generating pathways play the role in biological reactions which mainly involve oxidative and nitrosative stress. Nitric oxide is also capable of directly interacting with mitochondria through inhibition of respiration or by permeability transition. Reaction of nitric oxide with metal ions include its direct interaction with the metals or with oxo complexes thereby reducing them to lower valent state. Excessive production of nitric oxide can be studied by inhibiting the synthetic pathway of nitric oxide using both selective or specific nitric oxide synthase inhibitor or non-selective nitric oxide synthase inhibitor with respect to isoforms of nitric oxide.  相似文献   
4.
将云南牛蛭(P.yunnanensis)水蛭素基因的克隆测序结果与前人所报导的20个抗凝血因子和相对应的种属线粒体细胞色素氧化酶片段I(COI)比对,构建NJ进化树,以对吸血蛭类的分子进化机制及舌蛭科和医蛭亚目吸血特性的起源进行探究.结果表明:蛭类凝血抑制因子按相似性可分为以Hirudin家族蛋白和Antistasin蛋白家族为基础的两大类群;吻蛭目和无吻蛭目的吸血特性虽然起源不同,但可能共有一套相同位点的遗传基因.  相似文献   
5.
化学缓蚀剂在青铜器文物保护中的理论分析   总被引:1,自引:0,他引:1  
利用量子化学计算泛函密度理论中的B3LYP方法,在6-31 +G(d)基组上,对8种常见的在青铜器文物保护中使用的化学缓蚀剂化合物分子进行了结构和化学反应活性分析.结果表明化学缓蚀剂分子具有类平面型的共轭结构,其活性中心主要在氮原子上,通过对所有缓蚀剂分子的最高占有轨道(HOMO)、最低空轨道(LUMO)和能量差(ELUMO-EHOMO)△E分析后发现,苯并三氮唑(BTA)和2-氧代苯并咪唑(MBI)对青铜文物的保护性能较好.  相似文献   
6.
The calcineurin inhibitors (CNIs) [cyclosporin A (CsA) and tacrolimus (Tac)] are currently the most widely prescribed drugs for maintenance of immunosuppression after renal transplantation. These immunosuppressants are associated with side effects such as hyperlipidemia. We evaluated the differential effects of different CNIs on serum lipid parameters in renal transplant patients. Moreover, the aim of this study is to investigate the relationships between doses and blood levels of CNIs, and blood levels of CNIs and lipid parameters retrospectively. Two groups of 98 non-diabetic renal transplant patients, each treated with different CNIs, were studied: group A (n = 50, mean age: 31 ± 10 years), CsA, mycophenolate mofetil/azathioprin, steroid; group B (I = 48, mean age: 34 ± 12 years), Tac, mycophenolate mofetil/azathioprin, steroid. In renal transplant patients, CNIs blood levels and doses were examined at 1, 3, 6, 9, and 12 months after transplantation. Biochemical laboratory parameters including plasma lipids [total-cholesterol (CHOL), low-density lipoprotein (LDL)–CHOL, high-density lipoprotein (HDL)–CHOL, and triglycerides (TG)], CNI levels and doses were examined at 1, 3, 6, 9, and 12 months after transplantation. None of the patients received anti-lipidemic drugs during the study period. Blood levels of CNIs were detectable in all whole-blood samples by Cloned- Enzyme-Donor Immunoassay (CEDIA). The relationship between CNIs blood levels and CHOL, (LDL)–CHOL, HDL–CHOL, TG were evaluated. The mean serum CHOL levels and LDL–CHOL levels of patients in group A were found significantly higher than the patients in group B during the 12 month of follow up (p < 0.05). There was no significant difference in TG and HDL–CHOL plasma levels between group A and group B (p > 0.005). In group A the daily dose of CsA was significantly correlated with the mean blood levels of CsA at the 1st and 3rd months (r = 0.387, p = 0.005; r = 0.386, p = 0.006), respectively. In group A, the daily dose of CsA was significantly correlated with the mean serum TG levels during the 12 month of follow up (r = 0.420, p = 0.003). In group B, the daily dose of Tac was significantly correlated with the mean blood level of Tac (r = 0.335, p = 0.020) at the 1st month. No correlation was found between mean Tac blood levels and lipid parameters during the 12-month of follow up (p > 0.05). Significant positive correlation was observed between the CsA blood levels and LDL–CHOL levels (r = 0.338, p = 0.027) at the 3rd month. In the renal transplant patients with well functioning grafts, CsA therapy is associated with increased CHOL and LDL–CHOL ratio which represents an increased atherogenic risk tended to be associated with CsA. Serum LDL–CHOL levels may be effected by blood CsA levels.  相似文献   
7.
周进 《科教文汇》2014,(14):87-88
口语能力被视作衡量学生英语综合应用能力的重要指标之一,由于语言环境的缺失,我国口语课程存在着诸多阻滞因子。为有效提高大学口语教学的效率,教学中应导入可操作性、交际性和拓展性的创新策略。  相似文献   
8.
Insulin is a major protein hormone secreted by the β-cells of the pancreas and is important for the control of diabetes. Insulin is usually administered to diabetic patients through subcutaneous injection. This mode of therapy has certain inherent disadvantages such as local pain, itching and insulin lipodystrophy around the injection site. Hence, pharmaceutical scientists have been trying to design an oral delivery system for insulin. Many challenges are associated with the oral delivery of insulin, relating to the physical and chemical stability of the hormone, and its absorption and metabolism in the human body. Here we discuss various strategies for the oral delivery of insulin that are being tried out, as well as methods used to improve the absorption of orally consumed insulin and to reduce its degradation by digestive enzymes. K Gowthamarajan is on the faculty of the Department of Pharmaceutics in JSS College of Pharmacy, Ootacamund. His research interests are in the area of designing drug delivery systems for peptides and proteins. He is currently involved in research on pharmaceutical applications of plant polysaccharides. Giriraj T Kulkarni is on the faculty of the Department of Pharmaceutics in JSS College of Pharmacy, Ootacamund. Currently, he is involved in research on pharmaceutical and biotechnological applications of plant polysaccharides. He has authored a book ‘Biotechnology and its Applications in Pharmacy’ for undergraduate and postgraduate students of pharmacy.  相似文献   
9.
应用现代新材料来保护古代材料是文物保护和文物修复中所面临的重要课题,尤其是在青铜文物的保护和修复中,所用材料既要与文物相容性好,又要不损坏原器物上的考古信息、外观色彩与光泽。但经过科学研究工作者和文物工作者的共同努力,近年来复合封护剂在青铜文物保护中已取得了很大的进展。  相似文献   
10.
肿瘤血管生成是个多步骤的过程,众多肿瘤血管生成生长因子和抑制因子参与了对肿瘤血管生成的调控。血管生成抑制物是目前肿瘤研究中的热点。其中内源性肿瘤血管生成抑制物是人体内源性蛋白的一部分,在控制肿瘤的生长和转移过程中发挥重要作用,有着较好的抗癌前景。文章就内源性肿瘤血管生成抑制物的类型、作用机制和临床应用等作一综述。  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