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   926篇
  免费   60篇
  2023年   2篇
  2022年   2篇
  2021年   7篇
  2020年   6篇
  2019年   13篇
  2018年   20篇
  2017年   19篇
  2016年   27篇
  2015年   41篇
  2014年   35篇
  2013年   64篇
  2012年   70篇
  2011年   86篇
  2010年   57篇
  2009年   48篇
  2008年   62篇
  2007年   54篇
  2006年   64篇
  2005年   60篇
  2004年   56篇
  2003年   49篇
  2002年   33篇
  2001年   10篇
  1999年   6篇
  1998年   5篇
  1997年   6篇
  1996年   4篇
  1995年   4篇
  1994年   3篇
  1993年   6篇
  1992年   3篇
  1991年   8篇
  1990年   2篇
  1989年   7篇
  1988年   5篇
  1987年   4篇
  1986年   2篇
  1983年   3篇
  1982年   3篇
  1981年   3篇
  1980年   2篇
  1978年   5篇
  1977年   4篇
  1974年   5篇
  1972年   1篇
  1971年   1篇
  1970年   2篇
  1969年   2篇
  1966年   1篇
  1962年   2篇
排序方式: 共有986条查询结果,搜索用时 281 毫秒
911.
IkappaB Kinase (IKK)alpha is required for activation of an alternative NF-kappaB signaling pathway based on processing of the NF-kappaB2/p100 precursor protein, which associates with RelB in the cytoplasm. This pathway, which activates RelB:p52 dimers, is required for induction of several chemokine genes needed for organization of secondary lymphoid organs. We investigated the basis for the IKKalpha dependence of the induction of these genes in response to engagement of the lymphotoxin beta receptor (LTbetaR). Using chromatin immunoprecipitation, we found that the promoters of organogenic chemokine genes are recognized by RelB:p52 dimers and not by RelA:p50 dimers, the ubiquitous target for the classical NF-kappaB signaling pathway. We identified in the IKKalpha-dependent promoters a novel type of NF-kappaB-binding site that is preferentially recognized by RelB:p52 dimers. This site links induction of organogenic chemokines and other important regulatory molecules to activation of the alternative pathway.  相似文献   
912.
The human forkhead box O1A (FOXO1A) gene belongs to the human forkhead gene family and acts downstream of the human insulin signalling pathway. In this study, polymorphisms of the Intron I of FOXO1A gene were studied in Italian healthy people and insulin resistant subjects. No significant association between the germ-line variability in the Intron I of FOXO1A and insulin resistance was observed. Interestingly, during the study, a new 39-bp sequence insertion polymorphism in Intron I of FOXO1A gene was described. The polymorphism was found to co-segregate in a co-dominant Mendelian fashion and to be present in an ethnically distinct population (Greeks). A BLAST search showed that the sequence shares 100% identity with a mtDNA (mitochondrial DNA) sequence coding for the ATP synthase 8 (ATPase8) and ATP synthase 6 (ATPase6) genes. Hence, FOXO1A Intron I is a polymorphic nuclear region involved in the exchange of DNA material between mitochondrial and genomic DNA, which is a well-established mechanism of evolutionary change in eukaryotes.  相似文献   
913.
914.
915.
We have established a primary cell culture of the marine demosponge Ircinia muscarum. The culture was started from a cell suspension obtained by a combination of mechanical chemical means. Microbial contamination was controlled by the use of a pool of antibiotics. Optical density, rather than hemocytometer count, is suggested to monitor the cellular growth. Analysis of the chemical composition of I. muscarum cells revealed absence of sterols, showing that the cells were unable to biosynthesize sterols. When the medium was supplemented with cholesterol an increase of about 70% in the number of cells was observed. These results suggest that the classic mammalian nutrient medium was not satisfactory for I. muscarum cell growth, and sterols were needed to satisfy the membrane requirements. Received November 11, 2000; accepted January 14, 2001  相似文献   
916.
Several adsorbent materials were tested at 1 mg/ml for their in vitrocapacity to adsorb fumonisin B1 (FB1) from aqueous solutions. Cholestyramine showed the best adsorption capacity (85% from a solution containing 200 g/ml FB1) followed by activated carbon (62% FB1). Bentonite adsorbed only 12% of the toxin from a solution containing 13 g/ml FB1, while celite was not effective even at the lowest tested FB1 concentration (3.2 g/ml). Cholestyramine was tested in vivoto evaluate its capacity to reduce the bioavailability of fumonisins (FBs) in rats fed diet contaminated with toxigenic Fusarium verticillioidesculture material. Rats were exposed for one week to FBs-free diet, FBs-contaminated diet containing 6 or 20 g/g FB1 + FB2 and the same FBs-contaminated diet added of 20 mg/g cholestyramine. The increase of sphinganine/sphingosine (SA/SO) ratio in urine and kidney of treated rats was used as specific and sensitive biomarker of fumonisin exposure.The addition of cholestyramine to the FBs-contaminated diets consistently reduced the effect of FBs by reducing significantly (P < 0.05) both urinary and renal SA/SO ratios.This revised version was published online in October 2005 with corrections to the Cover Date.  相似文献   
917.
Nivolumab is a novel therapeutic option in NSCLC, associated with a significant survival gain compared with Docetaxel. However, predictive biomarkers are lacking. The presence of systemic inflammation has been correlated with poor outcome in many cancer types. We aimed to evaluate whether there is a correlation between some indicators of inflammation and response to Nivolumab or Docetaxel in pre‐treated NSCLCs. Data of 62 patients receiving Nivolumab or Docetaxel were analyzed. Baseline neutrophilia and thrombocytosis were not associated with response. High dNLR was associated with no response to Nivolumab, but not with Docetaxel, whereas high PLR correlated with low treatment response in both groups. Among refractory patients, a higher incidence of thrombocytosis, neutrophilia, high PLR, and high dNLR levels were observed compared with the overall population. This is one of the first reports in this field and suggests that indicators of inflammation might be included together with other predictive biomarkers in the baseline evaluation of patients candidate for immunotherapy.  相似文献   
918.
A summary of the First Signature Series Event, “Advancements in Cellular Therapies and Regenerative Medicine for Digestive Diseases,” held on May 3, 2017, in London, United Kingdom, is presented. Twelve speakers from three continents covered major topics in the areas of cellular therapy and regenerative medicine applied to liver and gastrointestinal medicine as well as to diabetes mellitus. Highlights from their presentations, together with an overview of the global impact of digestive diseases and a proposal for a shared online collection and data-monitoring platform tool, are included in this proceedings. Although growing evidence demonstrate the feasibility and safety of exploiting cell-based technologies for the treatment of digestive diseases, regulatory and methodological obstacles will need to be overcome before the successful implementation in the clinic of these novel attractive therapeutic strategies.  相似文献   
919.
Myeloid suppressor cells are a heterogeneous group of myeloid cells that are increased in patients with chronic myeloid leukaemia (CML) inducing T cell tolerance. In this study, we found that therapy with tyrosine kinase inhibitors (TKI) decreased the percentage of granulocytic MDSC, but only patients treated with dasatinib showed a significant reduction in the monocytic subset (M‐MDSC). Moreover, a positive correlation was observed between number of persistent M‐MDSC and the value of major molecular response in dasatinib‐treated patients. Serum and exosomes from patients with CML induced conversion of monocytes from healthy volunteers into immunosuppressive M‐MDSC, suggesting a bidirectional crosstalk between CML cells and MDSC. Overall, we identified M‐MDSC as prognostic factors in patients treated with dasatinib. It might be of interest to understand whether MDSC may be a candidate predictive markers of relapse risk following TKI discontinuation, suggesting their potential significance as practice of precision medicine.  相似文献   
920.
Wild medicinal and aromatic plants are in the market as herbal raw or processed and packaged materials, playing, even today, a strategic role in the production of plant-based products. Indeed, their content in active ingredients, mainly specialized secondary metabolites, is not constant; it undergoes significant seasonal variations, as abiotic stress heavily affects secondary metabolism network. The present review deals with the seasonality influence on the polyphenolic composition on antioxidant and anti-inflammatory properties of medicinal and aromatic plants. To this aim, firstly the factors influencing the content of active ingredients in a plant drug will be discussed, and, in particular, the increased occurrence of phenols as a response to abiotic stress. In the last part of the review a brief reference will be made to four meaningful case studies, which involve wild medicinal aromatic herbs, native to the Mediterranean area: Calamintha nepeta L. Savi, Foeniculum vulgare Mill., Ruta graveolens L. and Thymus longicaulis C. Presl. These species, grown in the same geographical area and collected at the same harvesting time, showed a great variability in phenol constituents throughout the year. The comparison among data acquired clearly evidences that the seasonal variation in polyphenols’ occurrence and amount leads to a more/less pronounced antioxidant and anti-inflammatory activity of the hydroalcoholic extract therefrom. It is worth of note that the presence of the same metabolite, but in different phytochemical complexes, could result in different biological activities.  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