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   152篇
  完全免费   7篇
  2018年   3篇
  2016年   1篇
  2014年   4篇
  2013年   3篇
  2012年   4篇
  2011年   7篇
  2010年   6篇
  2009年   9篇
  2008年   14篇
  2007年   9篇
  2006年   6篇
  2005年   7篇
  2004年   10篇
  2003年   12篇
  2002年   6篇
  2001年   1篇
  2000年   5篇
  1999年   5篇
  1998年   7篇
  1997年   4篇
  1996年   3篇
  1995年   3篇
  1994年   5篇
  1993年   3篇
  1992年   1篇
  1991年   4篇
  1990年   2篇
  1989年   3篇
  1988年   3篇
  1987年   2篇
  1986年   1篇
  1985年   1篇
  1984年   2篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
排序方式: 共有159条查询结果,搜索用时 31 毫秒
1.
Genes involved in flavonoid and stilbene biosynthesis were isolated from grape (Vitis vinifera L.). Clones coding for phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), chalcone isomerase (CHI), flavanone 3-hydoxylase (F3H), dihydroflavonol 4-reductase (DFR), leucoanthocyanidin dioxygenase (LDOX) and UDP glucose:flavonoid 3-O-glucosyl transferase (UFGT), were isolated by screening a cDNA library, obtained from mRNA from seedlings grown in light for 48 h using snapdragon (Antirrhinum majus) and maize heterologous probes. A cDNA clone coding for stilbene synthase (StSy) was isolated by probing the library with a specific oligonucleotide. These clones were sequenced and when the putative products were compared to the published amino acid sequence for corresponding enzymes, the percentages of similarity ranged from 65% (UFGT) to 90% (CHS and PAL). The analysis of the genomic organization and expression of these genes in response to light shows that PAL and StSy genes belong to large multigene families, while the others are present in one to four copies per haploid genome. The steady-state level of mRNAs encoded by the flavonoid biosynthetic genes as determined in young seedlings is coordinately induced by light, except for PAL and StSy, which appear to be constitutively expressed.  相似文献
2.
Plant genomes appear to exploit the process of gene duplication as a primary means of acquiring biochemical and developmental flexibility. Thus, for example, most of the enzymatic components of plant secondary metabolism are encoded by small families of genes that originated through duplication over evolutionary time. The dynamics of gene family evolution are well illustrated by the genes that encode chalcone synthase (CHS), the first committed step in flavonoid biosynthesis. We review pertinent facts about CHS evolution in flowering plants with special reference to the morning glory genus, Ipomoea. Our review shows that new CHS genes are recruited recurrently in flowering plant evolution. Rates of nucleotide substitution are frequently accelerated in new duplicate genes, and there is clear evidence for repeated shifts in enzymatic function among duplicate copies of CHS genes. In addition, we present new data on expression patterns of CHS genes as a function of tissue and developmental stage in the common morning glory (I. purpurea). These data show extensive differentiation in gene expression among duplicate copies of CHS genes. We also show that a single mutation which blocks anthocyanin biosynthesis in the floral limb is correlated with a loss of expression of one of the six duplicate CHS genes present in the morning glory genome. This suggests that different duplicate copies of CHS have acquired specialized functional roles over the course of evolution. We conclude that recurrent gene duplication and subsequent differentiation is a major adaptive strategy in plant genome evolution.  相似文献
3.
Transfer of a grapevine stilbene synthase gene to rice (Oryza sativa L.)   总被引:17,自引:0,他引:17  
A gene derived from grapevine (Vitis vinifera) coding for stilbene synthase has been transferred into protoplasts of the commercially important japonica rice cultivar Nipponbare using PEG-mediated direct gene transfer. Transgenic plants were regenerated from calli selected on kanamycin. Southern blot analysis of genomic DNA isolated from regenerants and progeny plants demonstrated that the stilbene synthase gene is stably integrated in the genome of transgenic rice plants and inherited in the offspring. The transient formation of stilbene-synthase-specific mRNA shortly after inoculation with the fungus of the rice blast Pyricularia oryzae has demonstrated that the grapevine stilbene synthase promoter is also active in monocotyledonous plants. Preliminary results indicate an enhanced resistance of transgenic rice to P. oryzae. Received: 1 July 1996 / Revision received: 5 November 1996 / Accepted: 30 November 1996  相似文献
4.
Dietary phytoestrogens and health   总被引:17,自引:0,他引:17  
The interest in the potential health effects of dietary phytoestrogens has increased with the findings that hormone replacement therapy is not as safe or effective as previously thought. This review summarizes the dietary sources of the phytoestrogens; isoflavonoids, stilbenes, coumestans and lignans. It also examines 105 clinical studies related to effects of phytoestrogens on bone density, cardiovascular health, cancer prevention, cognitive ability and menopausal symptoms.  相似文献
5.
A gene from groundnut (Arachis hypogaea) coding for stilbene synthase was transferred together with a chimaeric kanamycin resistance gene. It was found to be rapidly expressed after induction with UV light and elicitor in tobacco cells (Nicotiana tabacum). Comparative studies of stilbene synthase mRNA synthesis in groudnut and transgenic tobacco suspension cultures revealed the same kinetics of gene expression. Stilbene synthase specific mRNA was detectable 30 minutes after elicitor induction and 10 minutes after UV irradiation. The maximum of mRNA accumulation was between 2 and 8 hours post induction. 24 hours after induction stilbene synthase mRNA accumulation ceased. Furthermore, in transgenic tobacco plants, the gene was found to be inducible in sterile roots, stems and leaves. Stilbene synthase was demonstrated in crude protein extracts from transgenic tobacco cell cultures using specific antibodies. Resveratrol, the product of stilbene synthase, was identified by HPLC and antisera raised against resveratrol.  相似文献
6.
植物抗毒素转化水稻和转基因植株的生物鉴定   总被引:15,自引:0,他引:15  
用基因枪法转化了水稻(OryzasativaL.)6个材料的未成熟胚、成熟胚及胚性愈伤组织。质粒pSSVst1和pVE5+是由葡萄中分离出的编码芪类合成酶的植物抗毒素基因与35S或它自己的启动子组成。G418(100~150mg/L)或潮霉素(50mg/L)筛选后,经PCR、Southernblot或Dotblot分析证明的转基因植株共54株。对转基因植株及其后代进行了稻瘟病和白叶枯病的抗性鉴定。初步结果表明,芪类合成酶基因可以提高转基因植株及后代的抗性。  相似文献
7.
Expression of a chimeric stilbene synthase gene in transgenic wheat lines   总被引:11,自引:0,他引:11  
A chimeric stilbene synthase (sts)gene was transferred into wheat. Stilbene synthases play a role in the defence against fungal diseases in some plant species (e.g. groundnut or grapevine) by producing stilbenetype phytoalexins like resveratrol. Resveratrol is also claimed to have positive effects to human health. Embryogenic scutellar calli derived from immature embryos of the two commercial German spring wheat cultivars Combi and Hanno were used as target tissue for cotransformation by microprojectile delivery. The selectable marker/reporter gene constructs contained the bargene either driven by the ubiquitinpromoter from maize (pAHC 25, also containing the uidAgene driven by the ubiquitinpromoter), or by the actinpromoter (pDM 302) from rice. The cotransferred plasmid pStil 2 consisted of a grapevine stscoding region driven by the ubiquitin promoter. Eight transgenic Combi and one Hanno TOplant were obtained and, except one Combi TOplant, found to be cotransformants due to the integration of both the stsgene and the selectable marker or reporter genes. Expression of the stsgene was proven by RTPCR, and, for the first time, by detection of the stilbene synthase product resveratrol by HPLC and mass spectrometry. The stsgene was expressed in four of the seven transgenic Combi T_oplants. Two of the respective T1progenies segregated in a Mendelian manner were still expressing the gene. Investigations into methylation of the stsgene showed that in three nonexpressing progenies inactivation was paralleled by methylation.  相似文献
8.
芪合酶基因转化番茄产生白藜芦醇的研究   总被引:10,自引:0,他引:10  
为了获得含有白藜芦醇的转基因番茄,从葡萄雷司令中克隆到芪合酶基因,以之构建了含有组成型启动子的植物表达载体pBS2,用于农杆菌介导对番茄品种Tx00l4的遗传转化。通过对诱导愈伤、出芽、生根、再生植株的筛选,得到5株再生小苗,经PCR、Southem检测证实,有3株为真正的转基因植株。用HPLC对3株转基因植株叶片进行白藜芦醇含量鲜重分析,它们中白藜芦醇的含量分别为12.45μg/g,5.35μg/g,4.55μg/g。  相似文献
9.
A 13 kb DNA fragment was isolated from a grapevine (Vitis var. Optima) genomic library by hybridizing with elicitor-induced stilbene synthase cDNA as a probe. After fragmentation with Eco RI, subcloning and sequencing, two full-size stilbene synthase genes (Vst1 and Vst2) and the 3 end of a third stilbene synthase gene (Vst3) were located within the 13 kb fragment. Vst1 and Vst2, differing only slightly in the coding region, are distinguished in the intron size and in the structure of the promoter region. The 5 flanking region of gene Vst1 contains a TATAA box at nucleotide –48. The substantial structural differences found for the promoters of the two genes are paralleled by a striking difference in the expression of the two genes in elicitor-treated cells. Moreover, the accumulation upon elicitation of six different stilbene synthase mRNAs was studied and found to differ by two orders of magnitude.  相似文献
10.
 Transformation of barley and wheat via particle bombardment with a gene derived from Vitis vinifera L. (Vst1 gene) resulted in the expression of the foreign phytoalexin, resveratrol, in the transformed plants. Transgenic barley plants were regenerated from microspores and transgenic wheat plants from immature embryos were both selected on Basta. Stable integration of the gene in the genomes of transgenic barley and wheat plants, as well as their progeny, was analysed by Southern-blot analysis. The induction of the stilbene synthase promoter and the transient expression of stilbene synthase-specific mRNA after induction by wounding and infection were proofed in T1 and T2 progeny plants. An enhanced expression of the Vst1 gene under control of the stilbene synthase promoter was observed with enhancer sequences from the cauliflower mosaic virus 35s (CaMV 35s) promoter. The enzyme activity of the stilbene synthase was analysed in T1 progeny plants. The first pathological results indicated an increased resistance of transgenic barley plants to Botrytis cinerea used as a model experimental system. Received: 5 November 1997 / Accepted: 11 November 1997  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