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   194篇
  免费   14篇
  208篇
  2024年   1篇
  2023年   2篇
  2022年   4篇
  2021年   6篇
  2020年   7篇
  2019年   16篇
  2018年   12篇
  2017年   10篇
  2016年   5篇
  2015年   11篇
  2014年   20篇
  2013年   14篇
  2012年   16篇
  2011年   22篇
  2010年   14篇
  2009年   9篇
  2008年   4篇
  2007年   9篇
  2006年   8篇
  2005年   3篇
  2004年   6篇
  2001年   3篇
  2000年   1篇
  1991年   2篇
  1988年   1篇
  1986年   1篇
  1984年   1篇
排序方式: 共有208条查询结果,搜索用时 15 毫秒
151.
Zosima absinthifolia (Vent) Link (Apiaceae) is a perennial herb indigenous to Iran. It has been used as a medicinal plant from ancient time in Iran, Turkey and Pakistan. In the present work, air-dried and powdered plant roots were extracted with n-hexane, dichloromethane and methanol, respectively, using Soxhlet apparatus. The dichloromethane extract was subjected to vacuum liquid chromatography (VLC) and preparative thin layer chromatography (P-TLC) to yield two pyranocoumarins, aegelinol and agasyllin. The antimicrobial assay was performed using agar dilution method. The results showed that purified compounds have modest to weak antibacterial and antifungal activity.  相似文献   
152.
Adipose-derived stem cells (ADSCs) are a desirable stem cell source in neurodegenerative diseases treatment due to their ability to differentiate into different cell lineages. In this study, we transplanted human ADSCs (hADSCs) into a lysophosphatidylcholine (lysolecithin) model of multiple sclerosis (MS) and determined the efficiency of these cells in remyelination process. Forty adult rats were randomly divided into control, lysolecithin, vehicle, and transplantation groups, and focal demyelination was induced by lysolecithin injection into spinal cord. To assess motor performance, all rats were examined weekly with a standard EAE scoring scale. Four weeks after cell transplantation, to assess the extent of demyelination and remyelination, Luxol Fast Blue staining was used. In addition, immunohistochemistry technique was used for assessment of the presence of oligodendrocyte phenotype cells in damaged spinal cord. Our results indicated that hADSCs had ability to differentiate into oligodendrocyte phenotype cells and improved remyelination process. Moreover, the evaluation of rat motor functions showed that animals which were treated with hADSC compared to other groups had significant improvement (P < 0.001). Our finding showed that hADSCs transplantation for cell-based therapies may play a proper cell source in the treatment of neurodegenerative diseases such as MS.  相似文献   
153.
Inflammation is associated with immune cells infiltrating into the inflammatory site and pain. CC chemokine receptor 1 (CCR1) mediates trafficking of leukocytes to sites of inflammation. However, the contribution of CCR1 to pain is incompletely understood. Here we report an unexpected discovery that CCR1-mediated trafficking of neutrophils and CCR1 activity on non-hematopoietic cells both modulate pain. Using a genetic approach (CCR1−/− animals) and pharmacological inhibition of CCR1 with selective inhibitors, we show significant reductions in pain responses using the acetic acid-induced writhing and complete Freund''s adjuvant-induced mechanical hyperalgesia models. Reductions in writhing correlated with reduced trafficking of myeloid cells into the peritoneal cavity. We show that CCR1 is highly expressed on circulating neutrophils and their depletion decreases acetic acid-induced writhing. However, administration of neutrophils into the peritoneal cavity did not enhance acetic acid-induced writhing in wild-type (WT) or CCR1−/− mice. Additionally, selective knockout of CCR1 in either the hematopoietic or non-hematopoietic compartments also reduced writhing. Together these data suggest that CCR1 functions to significantly modulate pain by controlling neutrophil trafficking to the inflammatory site and having an unexpected role on non-hematopoietic cells. As inflammatory diseases are often accompanied with infiltrating immune cells at the inflammatory site and pain, CCR1 antagonism may provide a dual benefit by restricting leukocyte trafficking and reducing pain.  相似文献   
154.
An electrochemical immunosensing method was developed based on a magnetic nanocomposite. The multiwalled carbon nanotubes (MWCNTs) were treated with nitric acid to produce carboxyl groups at the open ends. Then, Fe3O4 nanoparticles were deposited on COOH–MWCNTs by chemical coprecipitation of Fe2+ and Fe3+ salts in an alkaline solution. Goat anti-human IgG (anti-hIgG) was covalently attached to magnetic nanocomposite through amide bond formation between the carboxylic groups of MWCNTs and the amine groups of anti-hIgG. The prepared bio-nanocomposite was used for electrochemical sensing of human tetanus IgG (hIgG) as a model antigen. The anti-hIgG magnetic nanocomposite was fixed on the surface of a gold plate electrode using a permanent magnet. The hIgG was detected using horseradish peroxidase (HRP)-conjugated anti-hIgG in a sandwich model. Electrochemical detection of hIgG was carried out in the presence of H2O2 and KI as substrates of HRP. Using this method, hIgG was detected in a concentration range from 30 to 1000 ng ml?1 with a correlation coefficient of 0.998 and a detection limit of 25 ng ml?1 (signal/noise = 3). The designed immunosensor was stable for 1 month.  相似文献   
155.
We have investigated the precision of peptide quantitation by MALDI-TOF mass spectrometry (MS) using six pairs of proteotypic peptides (light) and same-sequence stable isotope labeled synthetic internal standards (heavy). These were combined in two types of dilution curves spanning 100-fold and 2000-fold ratios. Coefficients of variation (CV; standard deviation divided by mean value) were examined across replicate MALDI spots using a reflector acquisition method requiring 100?000 counts for the most intense peak in each summed spectrum. The CV of light/heavy peptide centroid peak area ratios determined on four replicate spots per sample, averaged across 11 points of a 100-fold dilution curve and over all six peptides, was 2.2% (ranging from 1.5 to 3.7% among peptides) at 55 fmol total (light + heavy) of each peptide applied per spot, and 2.5% at 11 fmol applied. The average CV of measurements at near-equivalence (light = heavy, the center of the dilution curve) for the six peptides was 1.0%, about 17-fold lower CV than that observed when five peptides were ratioed to a sixth peptide (i.e., a different-sequence internal standard). Response curves across the 100-fold range were not completely linear but could be closely modeled by a power law fit giving R(2) values >0.998 for all peptides. The MALDI-TOF MS method was used to determine the endogenous level of a proteotypic peptide (EDQYHYLLDR) of human protein C inhibitor (PCI) in a plasma digest after enrichment by capture on a high affinity antipeptide antibody, a technique called stable isotope standards and capture by anti-peptide antibodies (SISCAPA). The level of PCI was determined to be 770 ng/mL with a replicate measurement CV of 1.5% and a >14?000-fold target enrichment via SISCAPA-MALDI-TOF. These results indicate that MALDI-TOF technology can provide precise quantitation of high-to-medium abundance peptide biomarkers over a 100-fold dynamic range when ratioed to same-sequence labeled internal standards and enriched to near purity by specific antibody capture. The robustness and throughput of MALDI-TOF in comparison to conventional nano-LC-MS technology could enable currently impractical large-scale verification studies of protein biomarkers.  相似文献   
156.

Background

ROR1 is a receptor tyrosine kinase expressed in chronic lymphocytic leukemia (CLL) and several other malignancies but absent in most adult normal tissues. ROR1 is considered an onco-fetal antigen. In the present study we analysed spontaneous humoral and cellular immunity against ROR1 in CLL patients.

Materials and Methods

Antibodies against ROR1 were analysed in 23 patients and 20 healthy donors by ELISA and Western blot. Purified serum IgG from patients was tested for cytotoxicity against CLL cells using the MTT viability assay. A cellular immune response against ROR1 derived HLA-A2 restricted 9 aa and 16 aa long peptides were analysed using peptide loaded dendritic cells co-cultured with autologous T cells from CLL patients (n = 9) and healthy donors (n = 6). IFN-γ, IL-5 and IL-17A-secreting T cells were assessed by ELISPOT and a proliferative response using a H3-thymidine incorporation assay.

Results

The majority of CLL patients had antibodies against ROR1. Significantly higher titers of anti-ROR1 antibodies were noted in patients with non-progressive as compared to progressive disease. The extracellular membrane-close ROR1 KNG domain seemed to be an immunodominant epitope. Ten patients with high titers of anti-ROR1 binding antibodies were tested for cytotoxicity. Five of those had cytotoxic anti-ROR1 antibodies against CLL cells. ROR1-specific IFN-γ and IL-17A producing T cells could be detected in CLL patients, preferentially in non-progressive as compared to patients with progressive disease (p<0.05).

Conclusion

ROR1 seemed to spontaneously induce a humoral as well as a T cell response in CLL patients. The data support the notion that ROR1 might be a specific neo-antigen and may serve as a target for immunotherapy.  相似文献   
157.
158.
One of the challenges encountered in microRNA (miRNA) studies is to observe their dual role in different conditions and cells. This leads to a tougher prediction of their behavior as gene expression regulators. miR-203 has been identified to play a negative role in the progression of malignant melanoma; however, it has been reported, with dual effect, as both an oncomiR and tumor suppressor miRNA in some malignancies, such as breast cancer, meanwhile, the role of miR-203 in melanoma stem cells or even metastatic cells is unclear. In the present study, after observation of upregulation of miR-203 in melanoma patient's serum and also melanospheres as cancer stem cells model, we examined its overexpression on the stemness potential and migration ability of melanoma cells. Our data demonstrated that the increased miR-203 level was significantly associated with significant increase in the ability of proliferation, colony and spheres formation, migration, and tumorigenesis in A375 and NA8 cells. All of these changes were associated with enhancement of BRAF, several epithelial to mesenchymal transition factors, and stemness genes. In conclusion, our results clearly determined that miR-203 could be down-regulateddownregulated in melanoma tissues but be overexpressed in melanoma stem cells. It has an important role as oncomiR and promote repopulation, tumorigenicity, self-renewal, and migration. Therefore, we suggested overexpression of miR-203 as biomarker for early detection of metastasis. However, more studies are needed to validate our data.  相似文献   
159.
Molecular Biology Reports - Olanzapine, an atypical antipsychotic medication, has been associated with weight gain and metabolic toxicity, especially in long term usage. Carnosic acid (CA), a major...  相似文献   
160.
Symmetrical 30-60% stenosis in a common carotid artery under unsteady flow condition for Newtonian and six non-Newtonian viscosity models are investigated numerically. Results show power-law model produces higher deviations, in terms of velocity and wall shear stress in comparison with other models while generalized power-law and modified-Casson models are more prone to Newtonian state. Comparing separation length of recirculation region at different critical points of cardiac cycle confirms the necessity of considering blood flow in unsteady mode. Increasing stenosis intensity causes flow patterns more disturbed downstream of the stenosis and WSS appear to develop remarkably at the stenosis throat.  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