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   313篇
  免费   13篇
  2024年   1篇
  2023年   8篇
  2022年   10篇
  2021年   22篇
  2020年   8篇
  2019年   13篇
  2018年   12篇
  2017年   19篇
  2016年   12篇
  2015年   19篇
  2014年   24篇
  2013年   29篇
  2012年   18篇
  2011年   20篇
  2010年   17篇
  2009年   8篇
  2008年   19篇
  2007年   10篇
  2006年   9篇
  2005年   14篇
  2004年   3篇
  2003年   1篇
  2002年   4篇
  2001年   3篇
  1999年   2篇
  1998年   3篇
  1997年   1篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1992年   3篇
  1991年   1篇
  1990年   1篇
  1989年   3篇
  1988年   2篇
  1987年   1篇
  1984年   1篇
  1981年   1篇
  1976年   1篇
排序方式: 共有326条查询结果,搜索用时 187 毫秒
181.
Tumor necrosis factor alpha (TNFalpha) is a pro-inflammatory cytokine that controls the initiation and progression of inflammatory diseases such as rheumatoid arthritis. Tpl2 is a MAPKKK in the MAPK (i.e. ERK) pathway, and the Tpl2-MEK-ERK signaling pathway is activated by the pro-inflammatory mediators TNFalpha, interleukin (IL)-1beta, and bacterial endotoxin (lipopolysaccharide (LPS)). Moreover, Tpl2 is required for TNFalpha expression. Thus, pharmacologic inhibition of Tpl2 should be a valid approach to therapeutic intervention in the pathogenesis of rheumatoid arthritis and other inflammatory diseases in humans. We have developed a series of highly selective and potent Tpl2 inhibitors, and in the present study we have used these inhibitors to demonstrate that the catalytic activity of Tpl2 is required for the LPS-induced activation of MEK and ERK in primary human monocytes. These inhibitors selectively target Tpl2 in these cells, and they block LPS- and IL-1beta-induced TNFalpha production in both primary human monocytes and human blood. In rheumatoid arthritis fibroblast-like synoviocytes these inhibitors block ERK activation, cyclooxygenase-2 expression, and the production of IL-6, IL-8, and prostaglandin E(2), and the matrix metalloproteinases MMP-1 and MMP-3. Taken together, our results show that inhibition of Tpl2 in primary human cell types can decrease the production of TNFalpha and other pro-inflammatory mediators during inflammatory events, and they further support the notion that Tpl2 is an appropriate therapeutic target for rheumatoid arthritis and other human inflammatory diseases.  相似文献   
182.

Background

Clostridium difficile strain 630Δerm is a spontaneous erythromycin sensitive derivative of the reference strain 630 obtained by serial passaging in antibiotic-free media. It is widely used as a defined and tractable C. difficile strain. Though largely similar to the ancestral strain, it demonstrates phenotypic differences that might be the result of underlying genetic changes. Here, we performed a de novo assembly based on single-molecule real-time sequencing and an analysis of major methylation patterns.

Results

In addition to single nucleotide polymorphisms and various indels, we found that the mobile element CTn5 is present in the gene encoding the methyltransferase rumA rather than adhesin CD1844 where it is located in the reference strain.

Conclusions

Together, the genetic features identified in this study may help to explain at least part of the phenotypic differences. The annotated genome sequence of this lab strain, including the first analysis of major methylation patterns, will be a valuable resource for genetic research on C. difficile.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1252-7) contains supplementary material, which is available to authorized users.  相似文献   
183.
Journal of Plant Growth Regulation - In this study, the effects of seed soaking in proline (12 mM) or Moringa oleifera leaf extract (MLE; 6%) on the biomass, yield, and the antioxidant...  相似文献   
184.
BACKGROUND: To describe the cytologic, histologic and immunohistochemical findings of a case of epithelial myoepithelial carcinoma (EMC) arising from a pleomorphic adenoma (PA) of the parotid with both malignant epithelial and myoepithelial components. CASE: A 29-year-old female presented with a 1.5 x 1.5-cm, palpable mass of the left parotid of 7-8 months' duration with recent enlargement and pain. Fine needle aspiration biopsy (FNAB) revealed biphasic epithelial (small cell) and myoepithelial (large/clear cell) clusters arranged in a pseudopapillary and trabecular pattern with abundant hyaline material with many naked nuclei, together with areas typical of pleomorphic adenoma (PA) was noted. The cytology was reported as salivary gland neoplasm, "suggestive of adenoid cystic carcinoma, less likely pleomorphic adenoma." The mass was excised and histologically reported as "pleomorphic adenoma, with focal invasion of one resected margin." Four months later the tumor recurred, and FNAB showed almost the same cytologic features as did the previous aspirate. Due to early recurrence, previous histologic sections were reviewed, and typical areas of a biphasic pattern of EMC with atypicality and mitosis of both components was found. The final diagnosis was EMC ex PA. CONCLUSION: Although previous reports mention the difficulties in diagnosing EMC and differentiation from the more common salivary gland neoplasms such as PA, we like to emphasize the cytologic confusion that results when the tumors coexist.  相似文献   
185.
This paper proposes the reconstruction of craniofacial fracture using rational cubic Ball curve. The idea of choosing Ball curve is based on its robustness of computing efficiency over Bezier curve. The main steps are conversion of Digital Imaging and Communications in Medicine (Dicom) images to binary images, boundary extraction and corner point detection, Ball curve fitting with genetic algorithm and final solution conversion to Dicom format. The last section illustrates a real case of craniofacial reconstruction using the proposed method which clearly indicates the applicability of this method. A Graphical User Interface (GUI) has also been developed for practical application.  相似文献   
186.
Strategic noise mapping provides important information for noise impact assessment and noise abatement. However, producing reliable strategic noise mapping in a dynamic, complex working environment is difficult. This study proposes the implementation of the random walk approach as a new stochastic technique to simulate noise mapping and to predict the noise exposure level in a workplace. A stochastic simulation framework and software, namely RW-eNMS, were developed to facilitate the random walk approach in noise mapping prediction. This framework considers the randomness and complexity of machinery operation and noise emission levels. Also, it assesses the impact of noise on the workers and the surrounding environment. For data validation, three case studies were conducted to check the accuracy of the prediction data and to determine the efficiency and effectiveness of this approach. The results showed high accuracy of prediction results together with a majority of absolute differences of less than 2 dBA; also, the predicted noise doses were mostly in the range of measurement. Therefore, the random walk approach was effective in dealing with environmental noises. It could predict strategic noise mapping to facilitate noise monitoring and noise control in the workplaces.  相似文献   
187.
Colorectal cancer (CRC) is among the most prevalent gastrointestinal cancers of epithelial origin worldwide, with over 2 million cases detected every year. Emerging evidence suggests a significant increase in the levels of inflammatory and stress-related markers in patients with CRC, indicating that oxidative stress and lipid peroxidation may influence signalling cascades involved in the progression of the disease. However, the precise molecular and cellular basis underlying CRC and their modulations during bioactive compound exposure have not yet been deciphered. This study examines the effect of caffeic acid phenethyl ester (CAPE), a natural bioactive compound, in HT29 CRC cells grown under serum-supplemented and serum-deprived conditions. We found that CAPE inhibited cell cycle progression in the G2/M phase and induced apoptosis. Migration assay confirmed that CAPE repressed cancer invasiveness. Protein localisation by immunofluorescence microscopy and protein expression by western blot analysis reveal increased expressions of key inflammatory signalling mediators such as p38α, Jun N-terminal kinase and extracellular signal-regulated kinase (ERK) proteins. Molecular docking data demonstrates that CAPE shows a higher docking score of −5.35 versus −4.59 to known p38 inhibitor SB203580 as well as a docking score of −4.17 versus −3.86 to known ERK1/2 inhibitor AZD0364. Co-immunoprecipitation data reveals that CAPE treatment effectively downregulates heat shock protein (HSP) expression in both sera-supplemented and limited conditions through its interaction with mitogen-activated protein kinase 14 (MAPK14). These results suggest that stress induction via serum starvation in HT29 CRC cells leads to the induction of apoptosis and co-ordinated activation of MAPK-HSP pathways. Molecular docking studies support that CAPE could serve as an effective inhibitor to target p38 and MAPK compared to their currently known inhibitors.  相似文献   
188.
Infection by LP-BM5 murine leukemia virus (MuLV) suppressed significantly the percentage of peripheral blood cells showing surface markers for macrophages, lymphocytes and activated lymphoid cells. Chronic administration of a 7% (36% calories) ethanol diet or injection of 1.9 mg/mouse/day of morphine for a 7 day period were followed by 3 week periods of abstinence and then 1 week periods of consumption of 5% ethanol diets or morphine injection to female C57BL/6 mice resulted in changes in the numbers of macrophages and lymphocyte subsets. The number of lymphocytes of various subsets were not significantly changed by the ethanol exposure except those showing activation markers which were reduced. The percentage of peripheral blood cells showing markers for macrophage functions and their activation were significantly reduced after "binge" use of ethanol. Ethanol retarded suppression of cells by retroviral infection. However by 25 weeks of infection there was a 8.6% survival in the ethanol fed mice infected with retrovirus which was much less than virally infected controls (45.0%). Morphine treatment also increased the percentage of cells with markers for macrophages and activated macrophages in virally infected mice, while suppressing them in uninfected mice. The second and third morphine injection series suppressed lymphocyte T-helper and T-suppressor cells, but not total T cells. However, suppression by morphine was significantly less during retroviral disease than suppression caused by the virus only. At 25 weeks of infection 44.8% of morphine treated, infected mice survived. Morphine treatment also caused deaths such that the survival in morphine treated, retrovirally infected was higher than would have been expected if the death rate in virally infected, and morphine injected animals were combined during combined treatment. Thus these drugs of abuse can modulate peripheral blood lymphoid subsets, suppression caused by retroviral infection, and survival.  相似文献   
189.
Background:Phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5) P3) and Phosphatidylinositol 4,5-trisphosphate (PtdIns(4,5) P2] form an insignificant amount of phospholipids but play important roles in controlling membrane-bound signalling. Little attention has been given to visualize and monitor changes or differences in the local generation of PtdIns(4,5) P2 and PtdIns(3,4,5) P3 in the cell membranes of MDA-MB-231 breast cancer cell lines.Methods:PLCδ1-PH-GFP and Btk-PH-GFP were used as biosensors to detected PtdIns(4,5) P2 and PtdIns(3,4,5)P3 respectively. These biosensors and antibodies were transfected, immuostained and then visualized by confocal microscopy on different cell surfaces.Results:Our results showed that PLCδ1-PH-GFP/mCherry was localized at the cell membrane, while Btk-PH-GFP/mCherry was sometimes localized at the cell membrane but there was also a large amount of fluorescence present in the cytosol and nucleus. Our results also showed that the cells that expressed low levels of Btk-PH-GFP the fluorescence was predominantly localised to the cell membrane. While the cells that expressed high levels of Btk-PH-GFP the fluorescence was localization in the cytosol and cell membrane. Our results demonstrated that both anti-PtdIns(4,5)P2 and anti-PtdIns(3,4,5)P3 antibodies were localized everywhere in cell.Conclusion:Our results suggest that PLCδ1-PH-GFP and Btk-PH-GFP/mCherry have more specificity, reliability, suitability and accuracy than antibodies in binding with and detecting PtdIns(4,5)P2 and PtdIns(3,4,5)P3 and in studying the molecular dynamics of phospholipids in live and fixed cells.Key Words: Antibodies, Biosensors, MDA-MB-231, Phosphatidylinositol  相似文献   
190.
Herein, a series of N''-benzylidene-3,4-dimethoxybenzohydrazide derivatives were designed and synthesised to target the multidrug efflux pump (MATE). The antibacterial activities were screened against S. aureus, Acinetobacter, S. typhi, E. coli, and P. aeruginosa, whereas their antifungal activities were screened against C. albicans. Compounds 4a, 4h, and 4i showed the most promising antibacterial and antifungal activities. Moreover, compounds 4h and 4i being the broader and superior members regarding their antimicrobial effects were selected to be further evaluated via in vivo testing using biochemical analysis and liver/kidney histological examination. Additionally, molecular docking was carried out to attain further deep insights into the synthesised compounds'' binding modes. Also, ADMET studies were performed to investigate the physicochemical/pharmacokinetics features and toxicity parameters of the synthesised derivatives. Finally, a structure-antimicrobial activity relationship study was established to facilitate further structural modifications in the future.

Highlights

  • A series of new N''-benzylidene-3,4-dimethoxybenzohydrazide derivatives were designed and synthesised targeting the multidrug efflux pump (MATE) guided by the pharmacophoric features of the co-crystallized native inhibitor of the target protein.
  • The newly synthesised compounds were assessed through in vitro, in vivo, and in silico approaches.
  • Using the agar well diffusion assay, the antibacterial activities of the synthesised compounds were screened against S. aureus, Acinetobacter, S. typhi, E. coli, and P. aeruginosa, whereas, their antifungal activities were screened against C. albicans.
  • The minimal inhibitory concentration (MIC) and the minimal bactericidal concentration (MBC) of the synthesised compounds were investigated on variable microbial species.
  • Compounds (4h and 4i) -as the broader and superior members regarding their antimicrobial effects- were further evaluated via in vivo testing using bio-chemical analysis and liver/kidney histological examination.
  • A molecular docking study and ADMET in silico studies were performed.
  • A structure-antimicrobial activity relationship study was established to facilitate further structural modifications in the future.
  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