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   774篇
  免费   93篇
  国内免费   2篇
  2024年   2篇
  2023年   4篇
  2022年   38篇
  2021年   43篇
  2020年   30篇
  2019年   85篇
  2018年   74篇
  2017年   49篇
  2016年   41篇
  2015年   45篇
  2014年   49篇
  2013年   69篇
  2012年   63篇
  2011年   53篇
  2010年   36篇
  2009年   22篇
  2008年   20篇
  2007年   26篇
  2006年   11篇
  2005年   10篇
  2004年   10篇
  2003年   13篇
  2002年   8篇
  2001年   4篇
  2000年   4篇
  1999年   5篇
  1998年   7篇
  1997年   2篇
  1996年   4篇
  1995年   4篇
  1994年   5篇
  1993年   3篇
  1992年   4篇
  1991年   1篇
  1990年   3篇
  1989年   4篇
  1988年   1篇
  1987年   2篇
  1986年   1篇
  1983年   3篇
  1982年   2篇
  1978年   2篇
  1977年   1篇
  1975年   1篇
  1974年   2篇
  1972年   1篇
  1966年   1篇
  1933年   1篇
排序方式: 共有869条查询结果,搜索用时 31 毫秒
101.
102.
Oxidative stress is a major component of harmful cascades activated in neurodegenerative disorders. Here, we tried to elucidate the possible neuroprotective effect of Salvigenin, a natural polyphenolic compound, on oxidative stress-induced apoptosis and autophagy in human neuroblastoma SH-SY5Y cells. We measured cell viability by MTT test and found that 25?μM is the best protective concentration of Salvigenin. GSH and SOD assays suggested that Salvigenin activates antioxidant factors. At the same time, measurement of ER stress-associated proteins including calpain and caspase-12 showed the ability of Salvigenin to decrease ER stress. We found that Salvigenin could decrease the apoptotic factors. Salvigenin inhibited H2O2-induced caspase-3 which is a hallmark of apoptosis in addition to reducing Bax\Bcl-2 ratio by 1.45 fold. Additionally, Salvigenin increased the levels of autophagic factors. Our results showed an increase in LC3-II/LC3-I ratio, Atg7, and Atg12 in the presence of 25?μM of Salvigenin by about 1.28, 1.25, and 1.54 folds, respectively, compared to H2O2-treated cells. So it seems that H2O2 cytotoxicity mainly results from apoptosis. Besides, Salvigenin helps cells to survive by inhibiting apoptosis and enhancing autophagy that opens a new horizon for the future experiments.  相似文献   
103.
104.
Prostate cancer is the most commonly diagnosed cancer in men worldwide and is the second leading cause of cancer related mortality. Genetic background may account for the difference in susceptibility of individuals to different diseases and the relationship between genetic polymorphism and some diseases has been extensively studied. There are several common polymorphisms in genes encoding DNA repair enzymes, some of these polymorphisms are reported to result in subtle structural alterations of the repair enzyme and modulation of the repair capacity. The aim of the present study was to analyze the effect of XPG Asp 1104His and XRCC1 Arg309Gln polymorphisms on risk of prostate cancer in north Indian population. Statistically significant increased risk of prostate cancer was observed on individuals that posses His/His genotype of XPG (OR 2.53, 95% CI 0.99–6.56, P = 0.031). In this study 150 prostate cancer diagnosed patients, 150 healthy controls and 150 BPH (benign prostate hyper plasia) were recruited from north Indian population. Moreover, individuals that carried the Gln/Gln genotype of XRCC1 also showed statistically increased risk of prostate cancer (OR 2.06, 95% CI 1.07–4.00, P = 0.033). The Asp/Asp of XPG and Gln/Gln of XRCC1 in combination showed statistically increased risk of prostate cancer in cases (OR 3.29, 95% CI 1.09–10.16, P = 0.032).  相似文献   
105.
The inhibitory effect of ethylenediamine on both activities of mushroom tyrosinase (MT) at 20 °C in a 10 mM phosphate buffer solution (pH 6.8), was studied. L-DOPA and L-tyrosine were used as substrates of catecholase and cresolase activities, respectively. The results showed that ethylenediamine competitively inhibits both activities of the enzyme with inhibition constants (K(i)) of 0.18±0.05 and 0.14±0.01 μM for catecholase and cresolase respectively, which are lower than the reported values for other MT inhibitors. For further insight a docking study between tyrosinase and ethylenediamine was performed. The docking simulation showed that ethylenediamine binds in the active site of the enzyme near the Cu atoms and makes 3 hydrogen bonds with two histidine residues of active site.  相似文献   
106.
The circulating population of peripheral T lymphocytes obtained from a blood sample can provide a large amount of information about an individual's medical status and history. Recent evidence indicates that the detection and functional characterization of antigen-specific T cell subsets within the circulating population may provide a diagnostic indicator of disease and has the potential to predict an individual's response to therapy. In this report, a microarray detection platform that combines grating-coupled surface plasmon resonance imaging (GCSPRI) and grating-coupled surface plasmon coupled emission (SPCE) fluorescence detection modalities were used to detect and characterize CD4(+) T cells. The microspot regions of interest (ROIs) printed on the array consisted of immobilized antibodies or peptide loaded MHC monomers (p/MHC) as T cell capture ligands mixed with additional antibodies as cytokine capture ligands covalently bound to the surface of a corrugated gold sensor chip. Using optimized parameters, an unlabeled influenza peptide reactive T cell clone could be detected at a frequency of 0.1% in a mixed T cell sample using GCSPRI. Additionally, after cell binding was quantified, differential TH1 cytokine secretion patterns from a T cell clone cultured under TH1 or TH2 inducing conditions was detected using an SPCE fluorescence based assay. Differences in the secretion patterns of 3 cytokines, characteristic of the inducing conditions, indicated that differences were a consequence of the functional status of the captured cells. A dual mode GCSPRI/SPCE assay can provide a rapid, high content T cell screening/characterization tool that is useful for diagnosing disease, evaluating vaccination efficacy, or assessing responses to immunotherapeutics.  相似文献   
107.
Abstract: Growth periodicity is a phenomenon occurring in fossil and modern corals. The most apparent feature is growth banding, and environmental changes are broadly accepted as controls on this phenomenon. If environment controls the growth, then all corallites within a colony should repeat the same growth pattern, as individuals are clones and must have shared the same environment. A study on several species of Alveolitidae (Anthozoa, Tabulata) from the Late Devonian (Early Frasnian) of the Holy Cross Mountains (Poland) shows that the growth pattern varies between neighbouring individuals within the same corallum. This contradicts observations of closely related Favositida as demonstrated on Pachyfavosites sp. from the Givetian of Avesnois, France, where neighbouring individuals repeat the same pattern. Therefore, environmental control on growth rhythm in Alveolitidae can be excluded; the causes of differences between individuals remain unknown.  相似文献   
108.
This paper reports on three species of mites of the genus Laelaspis in Iran - Laelaspis calidus Berlese from Pheidole pallidula, Laelaspis humeratus (Berlese) from Tetramorium caespitum and Laelaspis dariusi Joharchi & Jalaeian, sp. n. fromsoil. The new species is described and illustrations provided.  相似文献   
109.
Many theories of reflexology use ancient concepts which do not coincide with the modern medical terminology of anatomy, physiology and biophysics. This substantially reduces the trust of physicians in reflexology methods. During this research, several mathematical models for the interaction of the internal and biological active points of meridian structures have been proposed. The analysis of these models allows the specification of a list of heart diseases for which reflex diagnostics and reflex therapy methods are most effective and also allows increasing the effectiveness of these procedures. It is shown that good results for the prediction and early diagnosis of diseases from the reaction energy of biologically active points (acupuncture points) are obtained using fuzzy logic decision making.  相似文献   
110.
The potential of cell therapy is promising in nerve regeneration, but is limited by ethical considerations about the proper and technically safe source of stem cells. We report the successful differentiation of human EnSCs (endometrial stem cells) as a rich source of renewable and safe progenitors into high-efficiency cholinergic neurons. The extracellular signals of NGF (nerve growth factor) and bFGF (basic fibroblast growth factor) could induce cholinergic neuron differentiation. ChAT (choline acetyltransferase), MAP2 (microtubule associated protein 2) and NF-l (neurofilament L) increased after administration of bFGF and NGF to the EnSC cultures. trkC and FGFR2 (fibroblast growth factor receptor 2), which belong to the NGF and bFGF receptors respectively, were determined in populations of EnSCs. NGF, bFGF and their combination differentially influenced human EnSCs high efficiency differentiation. By inducing cholinergic neurons from EnSCs in a chemically defined medium, we could produce human neural cells without resorting to primary culture of neurons. This in vitro method provides an unlimited source of human neural cells and facilitates clinical applications of EnSCs for neurological diseases.  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