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排序方式: 共有3662条查询结果,搜索用时 33 毫秒
31.
32.
Raquel Alves dos Santos Teresinha Rosa Cabral Isabel Rosa Cabral Lusania Maria Greggi Antunes Cristiane Pontes Andrade Plínio Cerqueira dos Santos Cardoso Marcelo de Oliveira Bahia Claudia Pessoa José Luis Martins do Nascimento Rommel Rodríguez Burbano Catarina Satie Takahashi 《Biocell》2008,32(2):195-200
Physalis angulata L (Solanaceae) is a medicinal plant from North of Brazil, whose different extracts and infusions are commonly used in the popular medicine for the treatment of malaria, asthma, hepatitis, dermatitis and rheumatism. However, the genotoxic effects of P. angulata on human cells is not well known. The main purpose of the present study was to evaluate the in vitro genotoxic effects of aqueous extract of P. angulata using the comet assay and the micronucleus assay in human lymphocytes provided from 6 healthy donors. Treatments with P. angulata extracts were performed in vitro in order to access the extent of DNA damage. The comet assay has shown that treatments with P. angulata at 0.5, 1.0, 2.0, 3.0 and 6.0 microg/mL in culture medium were genotoxic. Lymphocytes treated with P. angulata at the concentrations of 3.0 and 6.0 microg/mL in culture medium showed a statistically significant increase in the frequency of micronucleus (p<0.05), however, the cytokinesis blocked proliferation index (CBPI) was not decreased after P. angulata treatment. In conclusion, the present work demonstrated the genotoxic effects of P. angulata extract on human lymphocytes in vitro. 相似文献
33.
S. Rombetto Yu. N. Ovchinnikov V. Corato P. Silvestrini E. Esposito C. Granata M. Russo R. Russo B. Ruggiero 《Open Systems & Information Dynamics》2007,14(2):209-216
We study the resonant quantum behaviour of a macroscopic superconducting system interacting with an external field. First
we consider the resonant tunneling assisted by microwave frequency in the moderate underdamped quantum regime. Then we consider
the resonant process in the extreme underdamped limit. In both regimes we have investigated a small frequency range, where
resonant phenomena take place. The transition probability W from the left to the right potential well has been numerically
calculated for an rf-SQUID as function of the external flux φ
x
for both regimes. Results indicate that, in a proper frequency and φ
x
range, the transition probability W can present two or three resonant peaks, depending on the damping regime. 相似文献
34.
Two commercial SCR catalysts, with a nominal W content of about 9 wt.% and a V nominal content of 0.55 and 1.8 wt.%, respectively, were contacted with different amounts of Na and K and with HCl vapours in order to simulate poisoning by species more specifically contained in exhaust gases from MSW combustion. Catalysts were characterised using XRD analysis, SEM/EDX analysis, BET and pore size distribution measurements, NH3 TPD, TG analysis. Poisoning agents do not cause loss of surface area nor pore occlusion. A significant loss of surface acidity was observed upon alkali metals poisoning whereas a decreasing of vanadium content was observed for the more concentrated catalysts upon HCl poisoning. Catalysts deactivation is proportional to the number of acid sites neutralised by alkali metals adsorbing ammonia in the temperature range typical of SCR process. HCl promotes the formation of new acid sites showing a lower activity compared to the original one. 相似文献
35.
Robert Leeb Felix Lee Claudia Keinrath Reinhold Scherer Horst Bischof Gert Pfurtscheller 《IEEE transactions on neural systems and rehabilitation engineering》2007,15(4):473-482
The step away from a synchronized or cue-based brain-computer interface (BCI) and from laboratory conditions towards real world applications is very important and crucial in BCI research. This work shows that ten naive subjects can be trained in a synchronous paradigm within three sessions to navigate freely through a virtual apartment, whereby at every junction the subjects could decide by their own, how they wanted to explore the virtual environment (VE). This virtual apartment was designed similar to a real world application, with a goal-oriented task, a high mental workload, and a variable decision period for the subject. All subjects were able to perform long and stable motor imagery over a minimum time of 2 s. Using only three electroencephalogram (EEG) channels to analyze these imaginations, we were able to convert them into navigation commands. Additionally, it could be demonstrated that motivation is a very crucial factor in BCI research; motivated subjects perform much better than unmotivated ones. 相似文献
36.
Castagna Claudia; Absil Philippe; Foidart Agnès; Balthazart Jacques 《Canadian Metallurgical Quarterly》1998,112(1):233
The authors investigated the behavioral actions of vasotocin (VT) in castrated testosterone-treated male Japanese quail. The appetitive and consummatory components of sexual behavior as well as the occurrence frequency of crows were inhibited, in a dose-dependent manner, by injections of VT. The authors observed opposite effects after injection of the V1 receptor antagonist, dPTyr(Me)AVP. Lower doses of VT were more active after central than after systemic injection, and effects of systemic injections of VT were blocked by a central injection of dPTyr(Me)AVP. The behavioral inhibition was associated with a modified diuresis after systemic but not central injection. These results provide direct evidence that VT affects male sexual behavior in quail by a direct action on the brain independent of its peripheral action on diuresis. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
37.
A Forlini A Fusco N Nasrollah M Hribal C Paganelli P Gentileschi F Russo G Sica AL Gaspari 《Canadian Metallurgical Quarterly》1998,19(6-7):257-261
A prospective study on the role of the p53 gene in sporadic colorectal neoplasms is presented and the level of mutant p53 protein was measured in the tissue removed during colonoscopy from: patients previously operated for colorectal malignant neoplasms, patients with active neoplasms, first degree relatives and during regular checks. 72% of patients with an active tumour showed a positive p53 and 38% in follow-up checks. Longer follow-up periods and a major number of patients are necessary to assess the prognostic importance of the p53 protein. 相似文献
38.
R Caylan A Titiz M Falcioni G De Donato A Russo A Taibah M Sanna 《Canadian Metallurgical Quarterly》1998,118(5):709-713
Experiments were designed to evaluate whether guanosine 3',5'-cyclic monophosphate (cGMP)-mediated mechanisms contribute to vasodilation via propofol in rat mesenteric resistance arteries. Ring segments were suspended in the myograph system for isometric tension recording, and responses to propofol were tested in the presence and absence of methylene blue (MB), an inhibitor of guanylate cyclase. At concentrations > or = 1 microM, propofol caused concentration-dependent relaxation of vessel rings precontracted with U46619 (a thromboxane analog). The effect was not affected by N-monomethyl-L-arginine (L-NMMA; 50 microM). MB (5 microM) reversed propofol-induced vasodilation by 30% (p < 0.001). In contrast, MB has no effect on nifedipine-inhibited vasocontraction. The propofol-induced relaxation was further tested in rings incubated in Ca2+-free solution. U46619-induced contractions were significantly reduced by propofol (40 microM) but not by nifedipine (1 microM). Propofol reduced to a similar degree the contractions obtained to exogenously added calcium chloride in the absence and the presence of MB. Furthermore, propofol (10-100 microM) increased cGMP content in cultured bovine vascular smooth-muscle cells. Soluble guanylate cyclase inhibitors, such as MB and LY83583, attenuated this effect. This investigation suggests that propofol-induced relaxations in small arteries, in addition to inhibition of calcium influx, are mediated by increases of cGMP in the smooth muscle cells. 相似文献
39.