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   270篇
  免费   10篇
  280篇
  2024年   1篇
  2023年   4篇
  2022年   8篇
  2021年   7篇
  2020年   9篇
  2019年   3篇
  2018年   8篇
  2017年   2篇
  2016年   11篇
  2015年   7篇
  2014年   19篇
  2013年   19篇
  2012年   19篇
  2011年   28篇
  2010年   19篇
  2009年   10篇
  2008年   13篇
  2007年   13篇
  2006年   9篇
  2005年   14篇
  2004年   11篇
  2003年   13篇
  2002年   12篇
  2001年   7篇
  2000年   1篇
  1999年   3篇
  1997年   2篇
  1995年   1篇
  1990年   1篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1979年   2篇
  1977年   1篇
排序方式: 共有280条查询结果,搜索用时 0 毫秒
31.
Hypogonadism, alopecia, diabetes mellitus, mental retardation, and extrapyramidal syndrome (also referenced as Woodhouse-Sakati syndrome) is a rare autosomal recessive multisystemic disorder. We have identified a founder mutation consisting of a single base-pair deletion in C2orf37 in eight families of Saudi origin. Three other loss-of-function mutations were subsequently discovered in patients of different ethnicities. The gene encodes a nucleolar protein of unknown function, and the cellular phenotype observed in patient lymphoblasts implicates a role for the nucleolus in the pathogenesis of this disease. Our findings expand the list of human disorders linked to the nucleolus and further highlight the developmental and/or maintenance functions of this organelle.  相似文献   
32.
1. Several toxic polypeptides were found in the venom of the scorpion Centruroides limpidus limpidus. Comparative studies of the potency of the venom in different strains of mice were conducted. 2. A new type of toxin (component II.9), specific for crustaceans (crayfish and isopods), was isolated from this scorpion and was shown to have the following N-terminal amino acid sequence: Lys-Lys-Asp-Gly-Tyr-Leu-Val-Asn-Lys-Tyr-Thr-Gly-Cys-Lys-Val-Asn-Cys- Tyr-Lys-Leu-Gly-Glu-Asn-Lys-Phe-Cys-Asn-Arg-Glu-. 3. A polypeptide toxic to mice (component II.6) from this venom was shown to have the following N-terminal sequence: Lys-Glu-Gly-Tyr-Leu-Val-Asn-His-Ser-Thr-Gly-Cys-Lys-Tyr- Glu-Cys-Tyr-Lys-Leu-Gly-Asp-Asn-Asp-Tyr-Cys-Leu-Arg-Glu-Cys-Lys-. 4. In cultured chick dorsal root ganglion cells, 1 microM of toxin II.6 was shown to reduce the size of sodium currents and to slow-down their activation-inactivation kinetics. The toxin had also a depressive action on the classical Ca2+ current activated at high membrane potentials (greater than 0 mV).  相似文献   
33.
34.
This plant tissue study of micropropagation identifies the selective medium saving for rapid propagation in cultivated Thermopsis turcica, an endangered germplasm of the family Fabaceae. The aim is to obtain the optimum growth medium of T. turcica by enabling the in vitro propagation of this endemic. In this study, the leaves and stems of T. turcica were cultured on a Murashige and Skoog’s medium supplemented with various concentrations (0.5, 1.0 and 2.0 mg L?1 1-Naphthaleneacetic acid) of auxin and (0.2 and 0.5 mg L?1 Zeatin) (1.0 and 2.0 mg L?1 Benzylaminopurine) of cytokinins. Previous research focused on the regeneration from the seed of T. turcica Eber population; we concentrated upon the regeneration of different plant parts (leaf and stem) of T. turcica Aksehir population. In addition, according to the literature on T. turcica that to date the effects of Zeatin on the regeneration has not been performed. The most promising regeneration and growth were obtained from leaf explants cultured on the media with 2.0 mg L?1 1-Naphthaleneacetic acid and 0.5 mg L?1Zeatin (93.3%). The regenerated plantles were rooted on the media containing 2.0 mg L?1 Indole-3-butyric acid. Rooted plantlets were transplanted into potting of sterilized soil. The present study reports on the sufficient in vitro regeneration protocol through organogenesis in T. turcica. The findings presented here have implications for in vitro protection and use of this endemic endangered species in further biotechnological research.  相似文献   
35.
36.
Oxidative stress is associated with various pathophysiological processes, including cell survival, adhesion, apoptosis, and cancer. In the present study, we aimed to evaluate the effects of H2O2‐induced toxicity on adipose tissue–derived stem cells (ADSCs) and whether 17β‐estradiol (E2) has protective effects on these cells. ADSCs derived from adult Sprague–Dawley rats were pretreated with different doses of E2 for 24 h and then exposed to 200 µM H2O2 for 4 h. Incubation of ADSCs with H2O2‐decreased cell viability in a concentration‐dependent fashion (p < 0.0001), whereas pretreatment of these cells with E2 significantly reversed toxicity (p < 0.05), inhibited apoptotic changes, and decreased lipid peroxidation (p < 0.0005). Our findings suggest that E2 protects ADSCs from oxidative‐induced cell death, and therefore, it may be used to improve the survival rate and regenerative capacity of stem cells. © 2012 Wiley Periodicals, Inc. J Biochem Mol Toxicol 26:301–307, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/jbt.21421  相似文献   
37.
Dioxacarb (Elecron, Famid) is a phenyl methylcarbamate insecticide and in vitro cytotoxic and genotoxic effects of this pesticide on human peripheral blood lymphocytes and Allium root meristematic cells were investigated by chromosomal aberrations (CAs) and Allium test. Human lymphocytes were treated with 62.5, 125, 250 and 500 ppm doses of dioxacarb for CAs. CA/cell, abnormal cell % and mitotic index % (MI %) data were obtained from these concentrations in 24 and 48 h treatment periods. Dioxacarb did not increase the CA/cell frequency significantly, so this insecticide was not identified as genotoxic. But it was found cytotoxic especially at 250 and 500 ppm concentrations because of the reduced the MI % and increased the abnormal cell %. In Allium test, 25 ppm (EC50/2), 50 ppm (EC50) and 100 ppm (EC50 × 2) concentrations were used for root growth inhibition (EC50 determination) and Allium mitotic index (MI) determination tests. The used concentrations of dioxacarb induced dose-dependent inhibition of MI and root growth on root meristems. Mitotic inhibition of dioxacarb was found significantly higher than for the positive control. These Allium results indicated the high cytotoxicity of dioxacarb. The present study is the first research on cytotoxicity and genotoxicity of dioxacarb by human lymphocyte CAs and Allium test.  相似文献   
38.
The aim of this study was to assess the therapeutic potential of oxytocin and liraglutide (LIR), a GLP‐1 analogue, in a rat model of vincristine‐induced neuropathy. Rats were injected with vincristine (VCR) at a dose of 4 mg/kg twice a week for 5 weeks. The VCR‐administered rats were divided into three groups and received saline, oxytocin, or liraglutide simultaneously with VCR. After the treatment period, electrophysiological, biochemical, histological, and immunohistochemical investigations were performed. Electromyography (EMG) recordings demonstrated significant alterations in the VCR + saline group (p < .001). Also, motor performance was decreased in the VCR + saline group (p < .05). Histologically, the axonal diameter was decreased in all groups. VCR + saline group showed significantly increased lipid peroxidation and decreased nerve growth factor (NGF) expression. However, the administration of oxytocin and liraglutide significantly prevented the EMG alterations, lipid peroxidation, and reduction in neuronal NGF expression. On the basis of these findings, oxytocin and liraglutide may be considered as potential agents for the prevention of VCR‐induced neuropathy.  相似文献   
39.
Adipose tissue-derived stem cells (ADSCs) are considered as a potential cell source for regenerative medicine and tissue engineering. Although ADSCs have greater proliferation capacity than bone marrow stem cells (BMSCs), lower differentiation ability of these cells limits their utility in experimental and clinical studies. The purpose of this study was to investigate whether 17β-estradiol (E(2)) has a stimulatory effect on osteogenic differentiation potential of ADSCs in vitro. ADSCs were isolated from visceral adipose tissues of rats and treated with different concentrations of E(2) in osteogenic medium (OM) for 21 days. The differences in osteogenic differentiation potential of the cultures were assessed by von Kossa staining, measurement of alkaline phosphatase (ALP) activity and calcium levels. ADSCs cultured in OM supplemented with E(2) showed greater bone-like nodule formation and mineral deposition in comparing with the cells grown in OM. In addition, ALP activity and calcium levels also were significantly higher in the cultures exposed to E(2) than the cells treated only with OM (p < 0.005, n = 5). Our results suggest that E(2) may stimulate the osteogenic differentiation of ADSCs and therefore, can be used as an inducing agent to improve the efficiency of these cells in in vitro and in vivo studies.  相似文献   
40.
In this study, three new axially disubstituted silicon phthalocyanines ( SiPc1–3 ) and their quaternized phthalocyanine derivatives ( QSiPc1–3 ) were prepared and characterized. The biological properties (antioxidant, antimicrobial, antibiofilm, and microbial cell viability activities) of the water-soluble silicon phthalocyanines were examined, as well. A 1 % DMSO diluted with pure water was used as a solvent in biological activity studies. All the compounds exhibited high antioxidant activity. They displayed efficient antimicrobial and antimicrobial photodynamic therapeutic properties against various microorganisms, especially Gram (+) bacteria. Additionally, they demonstrated high antibiofilm activities against S. aureus and P. aeruginosa. In addition, 100 % bacterial reduction was obtained for all the studied phthalocyanines against E. coli viable cells. Besides, the DNA cleavage and binding features of compounds ( QSiPc1–3 ) were studied using pBR322 DNA and CT-DNA, respectively. Furthermore, the human topoisomerase I enzyme inhibition activities of compounds QSiPc1 – 3 were studied. Anticancer properties of the water-soluble compounds were investigated using cell proliferation MTT assay. They exhibited anticarcinogenic activity against the human colon cancer cell line (DLD-1). Compounds QSiPc1 and QSiPc3 displayed a high anticarcinogenic effect on the DLD-1 cell line. The obtained results indicated that all the studied compounds may be effective biological agents and anticancer drugs after further investigations.  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