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   87篇
  免费   2篇
  国内免费   1篇
  2022年   6篇
  2021年   7篇
  2020年   2篇
  2018年   2篇
  2017年   1篇
  2016年   5篇
  2015年   1篇
  2014年   3篇
  2013年   7篇
  2012年   4篇
  2011年   7篇
  2010年   3篇
  2009年   4篇
  2008年   3篇
  2007年   4篇
  2006年   3篇
  2005年   7篇
  2004年   4篇
  2003年   3篇
  1999年   3篇
  1998年   1篇
  1994年   2篇
  1993年   1篇
  1991年   2篇
  1988年   1篇
  1987年   2篇
  1977年   1篇
  1975年   1篇
排序方式: 共有90条查询结果,搜索用时 953 毫秒
71.
The optimum concentrations of the plant hormones for in vitro regeneration and subsequent effect of auxins on rooting (in vitro and ex vitro) of shoots of Basella alba L. have been investigated in present study. Nodal shoot segments were used as explants to initiate the cultures. The bud breaking from explants was observed within 1 week of incubation on agar gelled Murashige and Skoog’s (MS) medium. Multiple axillary shoots (7.30 ± 0.56 shoots per explant) were induced on MS medium supplemented with 2.0 mg/L 6-benzylaminopurine (BAP). The shoots were multiplied (maximum 17.10 ± 0.44 shoots per explant) on the same medium fortified with 0.5 mg/L each of BAP and Kin (Kinetin) +0.1 mg/L IAA. These shoots were excised and rooted in vitro (10.73 ± 0.92 roots per shoot) on half-strength MS medium augmented with 2.0 mg/L indole-3 butyric acid (IBA). Hundred percentage success rates have been achieved by ex vitro rooting of the in vitro regenerated shoots with IBA at 300 mg/L. The in vitro and ex vitro rooted shoots were acclimatized in greenhouse and subsequently transferred to the natural field conditions where 100 % survival rate was reported. The ex vitro rooting method was found more advantageous than in vitro rooting in terms of time, energy and survival percentage of B. alba. A comparative foliar micromorphological study of B. alba was conducted to understand the micromorphological changes in plants while shifting from in vitro to the in vivo conditions in terms of variations in stomatal index, venation pattern and vein density, and the arrangement of crystals. The study could help in understanding the response of in vitro raised plants towards in vivo environment.  相似文献   
72.
A simple procedure for DNA isolation from processed dried commercial samples of tea is described. The method involves a modified CTAB procedure employing extensive washing, use of 1% PVP to remove polyphenolics and a single phenol:chloroform extraction step. The average yield ranges from 164–494 g/g tea sample for various market samples. The DNA obtained from 11 different brands of tea using this procedure were consistently amplifiable (using both RAPD primers as well as defined sequences as primers) and digestible with restriction endonucleases.  相似文献   
73.
The purpose of this study was to investigate the role of osteopontin (OPN) in diabetic hearts. Diabetes was induced in wild-type (WT) and OPN knockout (KO) mice by using streptozotocin (150 mg/kg) injection. Left ventricular (LV) structural and functional remodeling was studied 30 and 60 days after induction of diabetes. Induction of diabetes increased OPN expression in cardiac myocytes. Heart weight-to-body weight ratio was increased in both diabetic (D) groups. Lung wet weight-to-dry weight ratio was increased only in the WT-D group. Peak left ventricular (LV) developed pressures measured using Langendorff perfusion analyses were reduced to a greater extent in WT-D versus KO-D group. LV end-diastolic pressure-volume curve exhibited a significant leftward shift in WT-D but not in KO-D group. LV end-diastolic diameter, percent fractional shortening, and the ratio of peak velocity of early and late filling (E/A wave) were significantly reduced in WT-D mice as analyzed by echocardiography. The increase in cardiac myocyte apoptosis and fibrosis was significantly higher in the WT-D group. Expression of atrial natriuretic peptide and transforming growth factor-beta1 was significantly increased in the WT-D group. Induction of diabetes increased protein kinase C (PKC) phosphorylation in both groups. However, phosphorylation of PKC-betaII was significantly higher in the WT-D group, whereas phosphorylation of PKC-zeta was significantly higher in the KO-D group. Levels of peroxisome proliferator-activated receptor-gamma were significantly decreased in the WT-D group but not in the KO-D group. Thus increased expression of OPN may play a deleterious role during streptozotocin-induced diabetic cardiomyopathy with effects on cardiac fibrosis, hypertrophy, and myocyte apoptosis.  相似文献   
74.
Matrix metalloproteinases (MMPs), a family of extracellular endopeptidases, are implicated in angiogenesis because of their ability to selectively degrade components of the extracellular matrix. Interleukin-1 (IL-1), increased in the heart post-myocardial infarction (post-MI), plays a protective role in the pathophysiology of left ventricular (LV) remodeling following MI. Here we studied expression of various angiogenic genes affected by IL-1 in cardiac microvascular endothelial cells (CMECs) and investigated the signaling pathways involved in the regulation of MMP-2. cDNA array analysis of 96 angiogenesis-related genes indicated that IL-1 modulates the expression of numerous genes, notably increasing the expression of MMP-2, not MMP-9. RT-PCR and Western blot analyses confirmed increased expression of MMP-2 in response to IL-1. Gelatin in-gel zymography and Biotrak activity assay demonstrated that IL-1 increases MMP-2 activity in the conditioned media. IL-1 activated ERK1/2, JNKs, and protein kinase C (PKC), specifically PKC/1, and inhibition of these cascades partially inhibited IL-1-stimulated increases in MMP-2. Inhibition of PKC/1 failed to inhibit ERK1/2. However, concurrent inhibition of PKC/1 and ERK1/2 almost completely inhibited IL-1-mediated increases in MMP-2 expression. Inhibition of p38 kinase and nuclear factor-B (NF-B) had no effect. Pretreatment with superoxide dismutase (SOD) mimetic, MnTMPyP, increased MMP-2 protein levels, whereas pretreatment with SOD and catalase mimetic, EUK134, partially inhibited IL-1-stimulated increases in MMP-2 protein levels. Exogenous H2O2 significantly increased MMP-2 protein levels, whereas superoxide generation by xanthine/xanthine oxidase had no effect. This in vitro study suggests that IL-1 modulates expression and activity of MMP-2 in CMECs. MMP-2; protein kinase C; ERK1/2; JNK  相似文献   
75.
Three different commercially available media, known to support human and porcine-specific fibroblast cultures, were tested for their growth potential on goat skin explants. Although outgrowth of fibroblasts was observed in all media tested, irrespective of breed, porcine-specific media exhibited higher rate of growth. Using this media, three fibroblast cell lines (GSF289, GSF737, and GSF2010) from ear skin explants of normal healthy dairy goats of Kiko and Saanen breed were successfully established in culture. Liquid nitrogen stocks of these frozen cells had a viability rate of 96.2% in in vitro cultures. These cells were morphologically indistinguishable from the cell stocks prior to freezing. Analysis of the growth of a fifth passage culture revealed an ‘S’ shaped growth curve with a population doubling time of 25 h. The cell lines were found negative for microbial, fungal, and mycoplasma contaminations. These goat skin fibroblast lines and the simple method of their isolation and freezing with high rate of viability will provide additional tools to study molecular mechanisms that regulate fibroblast function and for genetic manipulation of small ruminants.  相似文献   
76.
Regioselective oxidation of unprotected and partially protected oligosaccharides is a much sought-after goal. Herein, we report a notable improvement in the efficiency of TEMPO-catalyzed oxidation by modulating the temperature of the reaction. Mono-, di-, and tri-saccharides are oxidized regioselectively in yields of 75 to 92%. The present method is simple to implement and is also applicable for selective oxidations of other mono- and poly-hydroxy compounds including unprotected and partially protected nucleosides.  相似文献   
77.
Plant Cell, Tissue and Organ Culture (PCTOC) - Spathoglottis plicata Blume is a vulnerable orchid species in various parts of the world, and the conventional propagation provides limited success to...  相似文献   
78.
β-Adrenergic receptor (β-AR) stimulation induces cardiac myocyte apoptosis and plays an important role in myocardial remodeling. Here we investigated expression of various apoptosis-related genes affected by β-AR stimulation, and examined first time the role of ataxia telangiectasia mutated kinase (ATM) in cardiac myocyte apoptosis and myocardial remodeling following β-AR stimulation. cDNA array analysis of 96 apoptosis-related genes indicated that β-AR stimulation increases expression of ATM in the heart. In vitro, RT-PCR confirmed increased ATM expression in adult cardiac myocytes in response to β-AR stimulation. Analysis of left ventricular structural and functional remodeling of the heart in wild-type (WT) and ATM heterozygous knockout mice (hKO) 28 days after ISO-infusion showed increased heart weight to body weight ratio in both groups. M-mode echocardiography showed increased percent fractional shortening (%FS) and ejection fraction (EF%) in both groups 28 days post ISO-infusion. Interestingly, the increase in %FS and EF% was significantly lower in the hKO-ISO group. Cardiac fibrosis and myocyte apoptosis were higher in hKO mice at baseline and ISO-infusion increased fibrosis and apoptosis to a greater extent in hKO-ISO hearts. ISO-infusion increased phosphorylation of p53 (Serine-15) and expression of p53 and Bax to a similar extent in both groups. hKO-Sham and hKO-ISO hearts exhibited reduced intact β1 integrin levels. MMP-2 protein levels were significantly higher, while TIMP-2 protein levels were lower in hKO-ISO hearts. MMP-9 protein levels were increased in WT-ISO, not in hKO hearts. In conclusion, ATM plays a protective role in cardiac remodeling in response to β-AR stimulation.  相似文献   
79.
Ataxia telangiectasia mutated kinase (ATM) is a cell cycle checkpoint protein activated in response to DNA damage. We recently reported that ATM plays a protective role in myocardial remodeling following β-adrenergic receptor stimulation. Here we investigated the role of ATM in cardiac remodeling using myocardial infarction (MI) as a model. Methods and Results: Left ventricular (LV) structure, function, apoptosis, fibrosis, and protein levels of apoptosis- and fibrosis-related proteins were examined in wild-type (WT) and ATM heterozygous knockout (hKO) mice 7 days post-MI. Infarct sizes were similar in both MI groups. However, infarct thickness was higher in hKO-MI group. Two dimensional M-mode echocardiography revealed decreased percent fractional shortening (%FS) and ejection fraction (EF) in both MI groups when compared to their respective sham groups. However, the decrease in %FS and EF was significantly greater in WT-MI vs hKO-MI. LV end systolic and diastolic diameters were greater in WT-MI vs hKO-MI. Fibrosis, apoptosis, and α-smooth muscle actin staining was significantly higher in hKO-MI vs WT-MI. MMP-2 protein levels and activity were increased to a similar extent in the infarct regions of both groups. MMP-9 protein levels were increased in the non-infarct region of WT-MI vs WT-sham. MMP-9 protein levels and activity were significantly lower in the infarct region of WT vs hKO. TIMP-2 protein levels similarly increased in both MI groups, whereas TIMP-4 protein levels were significantly lower in the infarct region of hKO group. Phosphorylation of p53 protein was higher, while protein levels of manganese superoxide dismutase were significantly lower in the infarct region of hKO vs WT. In vitro, inhibition of ATM using KU-55933 increased oxidative stress and apoptosis in cardiac myocytes.  相似文献   
80.
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