首页 | 官方网站   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   21篇
  免费   0篇
生物科学   21篇
  2023年   1篇
  2022年   3篇
  2021年   5篇
  2020年   2篇
  2019年   3篇
  2018年   1篇
  2016年   1篇
  2013年   1篇
  2012年   1篇
  2009年   1篇
  2005年   2篇
排序方式: 共有21条查询结果,搜索用时 0 毫秒
1.
Numerous cell types retrovirally transduced with macrophage colony-stimulating factor (M-CSF) using LXSN-based vectors showed a variable expression of the transgene. Expression of M-CSF correlated with the cells' adherent status. Transduced adherent cells produced the M-CSF, whereas the non-adherent cells synthesized little M-CSF. Studies showed that the 5'-UTR of the M-CSF gene regulated transgenic M-CSF gene expression. Ligation of this 5'-UTR to the enhanced green fluorescent protein gene (EGFP) caused the expression of EGFP to show the same dichotomy as previously seen with the M-CSF. Transgenic M-CSF was expressed within non-adherent cells when the 5'-UTR was removed from the LXSN vector. Quantitative real-time polymerase chain reaction analysis confirmed that lesser production of M-CSF mRNA occurred within the non-adherent cells than in the adherent cells. This difference was eliminated when the 5'-UTR was removed from the retroviral vector. Our work suggests that this 5'-UTR of the M-CSF gene could be an important way to get transgenic expression within adherent cells, but not in non-adherent cells.  相似文献   
2.
Dromedary camels (Camelus dromedarius) play a major economic role in many countries in Africa and Asia. Although they are resistant to harsh environmental conditions, they are susceptible to a wide range of zoonotic agents. This study aimed to provide an overview on the prevalence of selected zoonotic pathogens in blood and tissues of camels in central Iran. Blood, liver, portal lymph node, and brain were collected from 100 apparently healthy camels at a slaughterhouse in Qom city to assess the presence of DNA of Brucella spp., Trypanosoma spp., Coxiella burnetii, and Bartonella spp. PCR products were sequenced bidirectionally and phylogenetic analyses were performed. Eleven percent of camels tested positive for Brucella abortus (3%) and Trypanosoma evansi (8%). Coxiella burnetii and Bartonella spp. DNA was not detected. Our data demonstrate that camels from Iran contribute to the epidemiology of some zoonotic pathogens. Performing proper control strategies, such as vaccination of camels and humans in contact with them, test-and-slaughter policy, and education of the general population is necessary for minimizing the risk of zoonotic infection.  相似文献   
3.
Plant Cell, Tissue and Organ Culture (PCTOC) - In this research, the production of superior genotypes via the polyploidy induction method in two citrus species involved the tissue culture of stem...  相似文献   
4.
International Journal of Peptide Research and Therapeutics - Membrane proteins play important functions, such as cellular communication and transferring materials in the cell. Many membrane...  相似文献   
5.

The effect of Lactococcus lactis subsp. lactis strain PTCC 1403 as a potential probiotic was investigated on the growth, hematobiochemical, immune responses, and resistance to Yersinia ruckeri infection in rainbow trout. A total of 240 fish were distributed into 12 fiberglass tanks representing four groups (× 3 replicates). Each tank was stocked with 20 fish (average initial weight: 11.81 ± 0.32 g) and fed L. lactis subsp. lactis PTCC 1403 at 0 (control, T0), 1 × 109 (T1), 2 × 109 (T2), and 3 × 109 (T3) CFU/g feed for 8 weeks. The results showed enhanced protein efficiency ratio and reduced feed conversion ratio in the fish-fed T2 diet. Further, fish-fed T2 and T3 diets showed a significantly higher survival rate than the control (p < 0.05). Trypsin, lipase, and protease activities were increased in fish-fed L. lactis subsp. lactis PTCC 1403 compared to the control (p < 0.05). Fish fed with a T2 diet showed significantly (p < 0.05) lower glucose content than other groups. The blood lysozyme activity and IgM showed significantly (p < 0.05) higher values in fish-fed T2 and T3 diets than in other groups. The antioxidative responses were increased in fish-fed T2 and T3 diets (p < 0.05). After 7 days post-Y. ruckeri challenge, the cumulative mortality rate showed the lowest value in fish fed with T1 and T2 diets, while the highest value was recorded in the control group. In conclusion, the results revealed beneficial effects of L. lactis subsp. lactis PTCC 1403 on the feed efficiency, immune response, and resistance to Y. ruckeri infection in rainbow trout.

  相似文献   
6.
This study aims to synthesize some novel pyrazolo[1,5-a]pyrimidine derivatives, and investigate their biological activities. These compounds exhibited good to high antioxidant activities [2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capabilities]. Among them, Ethyl 5-(2-ethoxy-2-oxoethyl)-7-hydroxy-2-methylpyrazolo[1,5-a]pyrimidine-3-carboxylate ( 3h ) showed the highest antioxidant activity [Half-maximal Inhibitory Concentration (IC50)=15.34 μM] compared to ascorbic acid (IC50=13.53 μM) as a standard compound. Their antibacterial activities were investigated against two Gram-positive bacteria (Bacillus subtilis, and Staphylococcus aureus) and two Gram-negative bacteria (Pseudomonas aeruginosa, and Escherichia coli). The results showed that Ethyl 7-hydroxy-5-phenylpyrazolo[1,5-a]pyrimidine-3-carboxylate ( 3i ) has the best antibacterial activity against Gram-positive B. subtilis [Zone of Inhibition (ZOI)=23.0±1.4 mm, Minimum Inhibitory Concentration (MIC)=312 μM]. Also, the cytotoxicity of these compounds was assessed against breast cancer cell lines [human breast adenocarcinoma (MCF-7)], which 7-Hydroxy-2-methyl-5-phenylpyrazolo[1,5-a]pyrimidine-3-carbonitrile ( 3f ) displayed the most cytotoxicity (IC50=55.97 μg/mL), in contrast with Lapatinib (IC50=79.38 μg/mL) as a known drug.  相似文献   
7.
In this study, the synthesis of new spiropyrazoles, pyrazole and hydantoin heterocycles is reported by three component reactions of parabanic acids, hydrazine derivatives, and phenacyl bromides in the presence of triphenylphosphine as a nucleophile and triethylamine as a base in good to high yields (69–91 %). Evaluation of the synthesized compounds revealed a good to excellent antioxidant activities (37.6–96.2 %) using DPPH inhibitory potency. Among these compounds, hydantoin derivatives displayed higher antioxidant activities (93.7–96.2 %) comparing with spiropyrazoles and pyrazoles. The obtained results showed that Cl and Br substituents on the phenyl ring increased antioxidant activities of the related heterocycles. The antibacterial activities of the synthesized compounds were examined against two Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and two Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacteria. Among the synthesized heterocycles, 2-[1,3-dimethyl-2,5-dioxo-4-(2-oxo-2-phenylethyl)imidazolidin-4-yl]hydrazine-1-carbothioamide exhibited the excellent antibacterial activity against both Gram-positive and Gram-negative bacteria.  相似文献   
8.
The Central Asian racerunner, Eremias velox, is a widely distributed lizard of the Eurasian lacertid genus Eremias. Nucleotide sequences of mitochondrial genes, cyt b and 12S rDNA from 13 geographically distant localities in Iran and Central Asia, were analysed. Phylogenetic analyses of the sequence data unambiguously recovered five major clades within the E. velox complex with a high level of genetic divergence, indicating long periods of isolation. The basal position of the Iranian clades in the phylogenetic trees suggests that the E. velox clade originated on the Iranian plateau in the Middle Miocene. According to our calibrations, the northern Iranian clade diverged first some 10–11 Ma and that the Central Asian lineages split from the northeastern Iranian lineage approximately 6 Ma, most likely as a result of uplifting of the Kopet‐Dagh Mountains in the northern margin of the Iranian plateau. Topology of the phylogenetic trees, combined with the degree of the genetic distances among the independent lineages recovered in this study, provide a solid foundation for a fundamental revision of the taxonomic status of the major clades within this species complex.  相似文献   
9.
Combining a T9/9L glioma vaccine, expressing the membrane form of M-CSF, with a systemic antiangiogenic drug-based therapy theoretically targeted toward growth factor receptors within the tumor's vasculature successfully treated >90% of the rats bearing 7-day-old intracranial T9/9L gliomas. The antiangiogenic drugs included (Z)-3-[4-(dimethylamino)benzylidenyl]indolin-2-one (a platelet-derived growth factor receptor beta and a fibroblast growth factor receptor 1 kinase inhibitor) and oxindole (a vascular endothelial growth factor receptor 2 kinase inhibitor). A total of 20-40% of the animals treated with the antiangiogenic drugs alone survived, while all nontreated controls and tumor vaccine-treated rats died within 40 days. In vitro, these drugs inhibited endothelial cells from proliferating in response to the angiogenic factors produced by T9/9L glioma cells and prevented endothelial cell tubulogenesis. FITC-labeled tomato lectin staining demonstrated fewer and constricted blood vessels within the intracranial tumor after drug therapy. Magnetic resonance imaging demonstrated that the intracranial T9 glioma grew much slower in the presence of these antiangiogenic drugs. These drugs did not affect in vitro glioma cell growth nor T cell mitogenesis. Histological analysis revealed that the tumor destruction occurred at the margins of the tumor, where there was a heavy lymphocytic infiltrate. Real-time PCR showed more IL-2-specific mRNA was present within the gliomas in the vaccinated rats treated with the drugs. Animals that rejected the established T9/9L glioma by the combination therapy proved immune against an intracranial rechallenge by T9/9L glioma, but showed no resistance to an unrelated MADB106 breast cancer.  相似文献   
10.
The study of environmental conditions is one of the most important measures in the field of reforestation. The present study was undertaken to assess the environmental status of the mangrove forest of Alibaug, Maharashtra, India with respect to different sixteen physicochemical parameters of water using Geographical information system (GIS) for rehabilitation, conservation and development of the destructed area of the mangrove forest. The Base map of study area was prepared using topographic map and the remote sensing data of Landsat 7 ETM + for spatial analysis. The distributions of water pollutants were assigned using a GIS approach of Inverse Distance Weighted (IDW). The results showed that the amounts of EC, COD, hardness, O&G, Cl?, Na+, Ca2 +, Mg2 +, NO3? and PO43? are higher than the normal ranges in mangrove forest due to natural processes and human activity, industrial and domestic wastewater disposal, oil spillage and agricultural runoff which all eventually affect the water quality of mangrove forest of Alibaug. To identify the areas within the normal ranges of 16 studied parameter, suitability map of water was prepared through an integration of 16 suitability maps of the studied parameters. The suitability map of water classified the water to six classes of suitability in order of moderate > moderate to high > low to moderate > high > low suitable. The areas with classes of 1 and 2 were suitable for the protective measures. Classes 3 and 4 were suitable for replantation and restoration of native mangrove species as well as local communities' cooperation in the participatory protection measures. The areas of classes 5 and 0 need to be designed an urgent management and mitigation plan to reduce impact of human activities. The result of the study also proves the use of GIS as a powerful tool in addressing assessment and monitoring programs of the water quality in the mangrove ecosystems.  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-23

京公网安备 11010802026262号