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   50篇
  免费   4篇
化学   38篇
晶体学   1篇
力学   2篇
数学   4篇
物理学   9篇
  2023年   1篇
  2022年   3篇
  2021年   3篇
  2020年   3篇
  2018年   4篇
  2017年   1篇
  2016年   2篇
  2015年   2篇
  2014年   2篇
  2013年   4篇
  2012年   7篇
  2011年   5篇
  2010年   6篇
  2008年   1篇
  2006年   1篇
  2001年   1篇
  2000年   1篇
  1998年   1篇
  1995年   1篇
  1994年   1篇
  1979年   1篇
  1978年   2篇
  1977年   1篇
排序方式: 共有54条查询结果,搜索用时 31 毫秒
1.
Photodegradation of organic pollutants strongly depends on design of metal oxide semiconductor photocatalysts. Graphene, if composited with ZnO, can effectively enhance its photocatalytic performance for the eradication of pollutants from aqueous medium. Here in, ZnO-rGO is reported as highly active catalyst for degradation of methylene blue. A 200-mg/L solution of methylene blue dye was completely degraded within 1 h in comparison to 74% and 56% degradation over ZnO and rGO, respectively. The commonly used mechanisms of heterogeneous catalytic reactions, the Langmuir-Hinshelwood mechanism, and the Eley-Rideal mechanisms, were used to describe the reaction kinetics. The Langmuir-Hinshelwood mechanism was found as more favorable in this study. Apparent activation energy, Eap, true activation energy, ET, entropy, ΔS, and enthalpy, ΔH were calculated as 36.2 kJ/mol, 13.1 kJ/mol, 197.5 J/mol, and 23.1 kJ/mol, respectively.  相似文献   
2.
Alhagi camelorum (AC) is an old plant with a significant therapeutic value throughout Africa, Asia, and Latin America. The overuse of cisplatin (Cis > 50 mg/m2) is associated with observed nephrotoxicity, ototoxicity, gastrotoxicity, myelosuppression, and allergic reactions. Remedial measures are needed for the protection of nephrotoxicity against cisplatin. Thus, we investigated the nephroprotective effects of AC plant extract to prevent cisplatin-induced nephrotoxicity in albino Wistar rats. The presence of polyphenols, phenolic compounds, tannins, and saponins was revealed during phytochemical investigation, and a significantly intense antioxidant activity was recorded. There were no toxicological symptoms in the treated rats, and no anatomical, physiological, or histological abnormalities were found compared to the control rats. The results of correcting cisplatin-induced nephrotoxicity revealed that the extract has a significant ability to treat kidney damage, with most parameters returning to normal after only three weeks of therapy. It is concluded that co-administration of cisplatin with AC extract showed exceptional nephroprotective effects at a dose of 600 mg/kg for Cis-induced nephrotoxicity.  相似文献   
3.
4.
Domestically produced diagnostic cold kits, viz. glucoheptonate (GH), diisopropyliminodiacetic acid (DISIDA), dimercaptosuccinic acid (DMSA), diethylenetriamine-pentaacetic acid (DTPA), methylenediphosphonate (MDP) and Sn-colloid were labeled with99mTc and their in-vivo distribution in experimental animals (rats) was evaluated prior to use in humans for diagnostic scanning. The biodistribution pattern was found in accordance with the latest guidelines of the International Atomic Energy Agency (IAEA), which serve as a standard for small scale producers.  相似文献   
5.

Background

Immunotherapy to enhance the efficiency of the immune response in tuberculosis patients and to eliminate the persisters could be an additional valuable strategy to complement anti-mycobacterial chemotherapy. This study was designed to assess the immunotherapeutic potential of Ag85B as an adjunct to chemotherapy and its effect against active and persister bacteria left after therapy in mouse model of tuberculosis.

Methods

6-8 week old female Balb/c mice were infected with Mycobacterium tuberculosis and treated with chemotherapy or immunotherapy. Protective efficacy was measured in terms of bacterial counts in lungs and spleen. Immune correlates of protection in terms of Th1 and Th2 cytokines were measured by ELISA.

Results

Therapeutic effect of Ag85B was found to be comparable to that of short term dosage of antituberculous drugs (ATDs). The therapeutic effect of ATDs was augmented by the simultaneous treatment with rAg85B and moreover therapy with this protein allowed us to reduce ATD dosage. This therapy was found to be effective even in case of drug persisters. The levels of antigen specific IFNγ and IL-12 were significantly increased after immunotherapy as compared to the basal levels; moreover antigen specific IL-4 levels were depressed on immunotherapy with Ag85B.

Conclusion

We demonstrated in this study that the new combination approach using immunotherapy and concurrent chemotherapy should offer several improvements over the existing regimens to treat tuberculosis. The therapeutic effect is associated not only with initiating a Th1 response but also with switching the insufficient Th2 immune status to the more protective Th1 response.  相似文献   
6.
In this paper,we consider the family of generalized Petersen graphs P(n,4).We prove that the metric dimension of P(n,4) is 3 when n ≡ 0(mod 4),and is 4 when n = 4k + 3(k is even).For n ≡ 1,2(mod 4) and n = 4k + 3(k is odd),we prove that the metric dimension of P(n,4) is bounded above by 4.This shows that each graph of the family of generalized Petersen graphs P(n,4)has constant metric dimension.  相似文献   
7.
This paper describes a sensitive and reliable method for the determination of cocaine in human urine, plasma and red blood cells. Cocaine is extracted into cyclohexane from the biological materials at slightly alkaline pH, reduced with lithium aluminium hydride, acylated with pentafluoropropionic anhydride and detected by an electron capture detector. When compared with a gas chromatography-mass spectrometry method the results of cocaine determination correlated highly (r = 0.986). When cocaine was given intravenously to volunteer subjects only 0.2-1.4% of the administered dose was excreted as unmetabolized cocaine in the first 9 h after administration. Plasma and red blood cell levels of cocaine were also determined by this method after intravenous administration.  相似文献   
8.
This paper reports proton and methanol transport behavior of composite membranes prepared for use in the direct methanol fuel cell (DMFC). The composite membranes were prepared by embedding various proportions (10–30 wt.%) of inorganic proton conducting material (tungstophosphoric acid (TPA)/MCM-41) into sulfonated poly(ether ether ketone) (SPEEK) polymer matrix. The results indicate that the proton conductivity of the membranes increases with increasing loading of solid proton conducting material. The highest conductivity value of 2.75 mS/cm was obtained for the SPEEK composite membrane containing 30 wt.% solid proton conducting material (50 wt.% TPA in MCM-41). The methanol permeability and crossover flux were also found to increase with increasing loading of the solid proton conducting material. Lowest permeability value of 5.7 × 10−9 cm2 s−1 was obtained for composite membrane with 10 wt.% of the solid proton conducting material (40 wt.% TPA in MCM-41). However, all the composite membranes showed higher selectivity (ratio between the proton conductivity and the methanol permeability) compared to the pure SPEEK membrane. In addition, the membranes are thermally stable up to 160 °C. Thus, these membranes have potential to be considered for use in direct methanol fuel cell.  相似文献   
9.
The proliferation of information and communication technology has made exchange of information easier than ever. Security and copyright protection of multimedia contents in such a scenario has become a major challenge for the research community round the globe. Digital watermarking has been found as an effective tool for protection and security of multimedia content. A secure and robust watermarking scheme based on DC coefficient modification in pixel domain and a modified logistic map is presented in this paper. The cover image is divided into \(8 \times 8\) sub-blocks and instead of computing DC coefficient using discrete cosine transform (DCT), we compute DC coefficient of each block in spatial domain. Watermark bits are embedded by modifying DC coefficients of various blocks in spatial domain. The quantum of change to be brought in various pixels of a block for embedding watermark bit depends upon DC coefficient of respective blocks, nature of watermark bit (0 or 1) to be embedded and the adjustment factor. The security of embedded watermark has been taken care of by using chaotic encryption based on a generalized logistic map (GLM). We show that GLM has better properties like ergodicity, larger lyapunov exponent, uniform invariant density, mixing, higher range of bifurcation parameter etc., compared to basic logistic map. We exploit these properties of GLM for designing a secure robust, strong efficient cryptosystem to encrypt the watermark information before embedding it. Experimental investigations show that besides being highly secure the proposed technique is robust to both signal processing and geometric attacks. Further, the proposed scheme is computationally efficient as DC coefficient which holds the information is computed in pixel domain instead of using DCT on an image block.  相似文献   
10.
Methanolic leaf and fruit extracts of Datura metel were found highly effective in suppressing against Macrophomina phaseolina, the cause of charcoal rot disease. These extracts were further subjected to successive fractionation with n-hexane, chloroform, ethyl acetate and n-butanol. All the concentrations (3.125-200?mg?mL?1) of chloroform, ethyl acetate and n-butanol fractions of leaf extract, and n-hexane fraction of fruit extract completely inhibited the target fungal growth. Two compounds A and B from the n-hexane fraction of fruit extract and compound C from n-butanol fraction of leaf extract were obtained by TLC. Compound B exhibited the best antifungal activity with an MIC value of 7.81?μg?mL?1 that was at par with that of commercial fungicide mancozeb (80% w/w). This study concludes that M. phaseolina can be effectively controlled by natural antifungal compounds in n-hexane fraction of methanolic fruit extract of D. metel.  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