全文获取类型
收费全文 | 50篇 |
免费 | 2篇 |
国内免费 | 10篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2014年 | 1篇 |
2011年 | 2篇 |
2010年 | 2篇 |
2008年 | 4篇 |
2007年 | 4篇 |
2005年 | 3篇 |
2004年 | 2篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 5篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有62条查询结果,搜索用时 31 毫秒
1.
The effect of substances with different redox potentials in the phytochrome-controlled germination of Paulmtnia tomentosa seeds was examined. Up to 25% of water-imbibed seeds germinated upon irradiation with 5 min red light The seeds irradiated with 5 min red light and incubated in substances with redox potentials equal or higher than E'0 = 360 mV [potassium nitrate, potassium hexacyanoferrate (III) or potassium hexachloroiridate (IV)] and sodium nitroprusside germinated up to 80%. The optimal concentration was between 1 and 10 mM. Other electron acceptors such as 2.6-dichlorophenol-indoplhenol, phenazine methosulfate and methylene blue failed to produce and effect. The germination-promoting effect was obtained when the substances were supplied to the incubation medium from the onset of imbibition or at the onset of irradiation. Delay of application of these chemicals until after the red light treatment diminished their effectiveness and the effect was lost after 48 h. The escape from far-red reversibility was evident in the presence of substances which stimulated germination. The results presented support the view that phytochrome-broken dormancy of Paulownia tomentosa seeds is closely connected with redox changes. 相似文献
2.
Bing Liu Yun‐Hong Tan Su Liu Richard G. Olmstead Dao‐Zhang Min Zhi‐Duan Chen Nirmal Joshee Brajesh N. Vaidya Richard C. K. Chung Bo Li 《植物分类学报:英文版》2020,58(1):1-17
The familial placements of Cyrtandromoea Zoll. and Wightia Wall., two small and enigmatic South‐East Asian genera, have long been controversial in Lamiales. Here we adopt a two‐step approach to resolve their phylogenetic relationships. We initially reconstructed a large‐scale phylogeny of Lamiales using six chloroplast markers (atpB, matK, ndhF, psbBTNH, rbcL, and rps4). The results showed that both Cyrtandromoea and Wightia emerged in the LMPO clade, including Lamiaceae, Mazaceae, Phrymaceae, Paulowniaceae, and Orobanchaceae. Based on the second set of six chloroplast markers (atpB, matK, ndhF, rbcL, rps16, and trnL‐F) and two nuclear ribosomal regions (external transcribed spacer and internal transcribed spacer) for the analyses focusing on the LMPO clade, our results revealed that Cyrtandromoea was consistently nested within Phrymaceae, whereas Wightia was supported as sister to Phrymaceae by the chloroplast DNA dataset or sister to Paulowniaceae by the nuclear ribosomal DNA dataset. Morphological and anatomical evidence fully supports the inclusion of Cyrtandromoea in Phrymaceae, and an updated tribal classification is done for Phrymaceae with five tribes, that is, Cyrtandromoeeae Bo Li, Bing Liu, Su Liu & Y. H. Tan, trib. nov., Diplaceae Bo Li, Bing Liu, Su Liu & Y. H. Tan, trib. nov., Leucocarpeae, Mimuleae, and Phrymeae. The conflicting phylogenetic position of Wightia indicated by different genome markers results in difficulty placing the genus in either Phrymaceae or Paulowniaceae. Considering the distinct morphological differences between Wightia and other families in the LMPO clade, we here propose a new family, Wightiaceae Bo Li, Bing Liu, Su Liu & Y. H. Tan, fam. nov., to accommodate it, which is the 26th family recognized in Lamiales. 相似文献
3.
Background and Aims: Recent studies have shown that small structures on plant surfacesserve ecological functions such as resistance against herbivores.The morphology, distribution, chemical composition and changesduring shoot and leaf development of such small structures wereexamined on Paulownia tomentosa. Methods: The morphology and distribution of the structures were studiedunder light microscopy, and their chemical composition was analysedusing thin-layer chromatography and high-performance liquidchromatography. To further investigate the function of thesestructures, several simple field experiments and observationswere also conducted. Key Results: Three types of small structures on P. tomentosa were investigated:bowl-shaped organs, glandular hairs and dendritic trichomes.The bowl-shaped organs were densely aggregated on the leavesnear flower buds and were determined to be extrafloral nectarines(EFNs) that secrete sugar and attract ants. Nectar productionof these organs was increased by artificial damage to the leaves,suggesting an anti-herbivore function through symbiosis withants. Glandular hairs were found on the surfaces of young and/orreproductive organs. Glandular hairs on leaves, stems and flowerssecreted mucilage containing glycerides and trapped small insects.Secretions from glandular hairs on flowers and immature fruitscontained flavonoids, which may provide protection against someherbivores. Yellow dendritic trichomes on the adaxial side ofleaves also contained flavonoids identical to those secretedby the glandular hairs on fruits and flowers. Three specialtypes of leaves, which differed from the standard leaves inshape, size and identity of small structures, developed nearyoung shoot tips or young flower buds. The density of smallstructures on these leaf types was higher than on standard leaves,suggesting that these leaf types may be specialized to protectyoung leaves or reproductive organs. Changes in the small structuresduring leaf development suggested that leaves of P. tomentosaare primarily protected by glandular hairs and dendritic trichomesat young stages and by the EFNs at mature stages. Conclusions: The results indicate that P. tomentosa protects young and/orreproductive organs from herbivores through the distributionand allocation of small structures, the nature of which dependson the developmental stage of leaves and shoots. 相似文献
4.
Geranylated flavanones from the secretion on the surface of the immature fruits of Paulownia tomentosa 总被引:2,自引:0,他引:2
Chemical investigation of the methanol extract of the viscous secretion on the surface of immature fruits of Paulownia tomentosa furnished nine geranylated flavanones, 6-geranyl-5,7-dihydroxy-3',4'-dimethoxyflavanone (1), 6-geranyl-3',5,7-trihydroxy-4'-methoxyflavanone (2), 6-geranyl-4',5,7-trihydroxy-3',5'-dimethoxyflavanone (3), 6-geranyl-4',5,5',7-tetrahydroxy-3'-methoxyflavanone (4), 6-geranyl-3,3',5,7-tetrahydroxy-4'-methoxyflavanone (5), 4',5,5',7-tetrahydroxy-6-[6-hydroxy-3,7-dimethyl-2(E),7-octadienyl]-3'-methoxyflavanone (6), 3,3',4',5,7-pentahydroxy-6-[6-hydroxy-3,7-dimethyl-2(E),7-octadienyl]flavanone (7), 3,3',4',5,7-pentahydroxy-6-[7-hydroxy-3,7-dimethyl-2(E)-octenyl]flavanone (8), and 3,4',5,5',7-pentahydroxy-3'-methoxy-6-(3-methyl-2-butenyl)flavanone (9), along with six known geranylated flavanones. Among these, compounds 4, 6-9 and the known 6-geranyl-3',4',5,7-tetraahydroxyflavanone (diplacone), 6-geranyl-3,3',4',5,7-pentahydroxyflavanone (diplacol) and 3',4',5,7-pentahydroxy-6-[7-hydroxy-3,7-dimethyl-2(E)-octenyl]flavanone showed potent radical scavenging effects towards DPPH radicals. 相似文献
5.
6.
泡桐叶片蛋白质提取方法的研究 总被引:7,自引:1,他引:6
24个提取泡桐叶片蛋白质组合的试验结果表明,用UKC(9.5mol/L尿素,5mmol/LK2CO3,1.25%CTAB,0.5%二硫苏糖醇,2%两性载体电解质pH3.5~10,5%TritonX-100)提取由10%冷(-40℃)三氯醋酸(丙酮配制,内含0.07%的巯基乙醇)处理的泡桐叶片干粉提取出的蛋白质总量和种类最多。这表明该方法可用于泡桐叶片蛋白质的提取。 相似文献
7.
作者研究了山明桐(Paulownia sp.)小孢子败育及小孢子囊壁异常发育的过程,并探讨了两者之间的关系。结果表明:小孢子败育发生在减数分裂至单核小孢子期间。在小孢子有丝分裂前小孢子已全部敗育拚辈惴⒂斐V饕硐衷诒3只疚唇到饣虬虢到庾刺敝脸墒旎ㄒ┦逼凇R┦夷诒谙赴┓只鎏踝丛龊裣赴凇P℃咦幽冶诜⒂械恼庑┮斐O窒蟮氖抵适瞧湔7⒂瘫恢型就V?而以幼态保持至花药最后干缩。观察表明小孢子囊壁发育异常不是小孢子败育的原因,而可能是其结果。 相似文献
8.
模拟酸雨和铜复合污染对白花泡桐生理特性的影响及其解毒机制 总被引:2,自引:0,他引:2
采用盆栽方法,研究了模拟酸雨(pH分别为4.0、5.0)和Cu(0~200mg·kg-1)复合污染对白花泡桐生理特性的影响及其解毒机制.结果表明:未加Cu处理时,不同酸雨处理间,白花泡桐的叶绿素、类胡萝卜素、超氧阴离子、过氧化氢和丙二醛含量均差异不显著;100和200mg·kg-1Cu处理时,pH4.0处理的叶绿素和类胡萝卜素含量显著低于,而超氧阴离子、过氧化氢和丙二醛含量显著高于pH5.0处理.Cu处理的叶绿素a/b值明显高于未加Cu处理.随着酸雨酸度增加,叶片铜含量明显减少,而根部铜含量明显增加.pH5.0时,随Cu浓度增加,超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性均持续增强,植物络合素和谷胱甘肽(GSH)总量均明显增加;而在pH4.0时,SOD、POD、CAT和APX活性呈先升后降,而GSH总量在Cu浓度为200mg·kg-1时明显下降.模拟酸雨加剧了高浓度Cu对白花泡桐的氧化胁迫. 相似文献
9.
Influence of petiole and lamina on adventitious shoot initiation from leaf explants of Paulownia fortunei 总被引:2,自引:0,他引:2
Adventitious shoot bud differentiation occurred preferentially from the petiolar cut ends of leaf explants of Paulownia fortunei cultured on Murashige and Skoog medium supplemented with 4 μmα-naphthaleneacetic acid and 20 μm benzyladenine. The details of plantlet regeneration and successful transplantation to soil have been reported earlier. We
now show that besides medium supplementation with auxin and cytokinin, the presence of lamina and petiole in the explant influence
shoot bud induction. Explants with the basal half of the lamina and the entire petiole were much more responsive than those
with whole lamina and petiole. A dual-culture-medium technique which permitted incubation of the two ends of excised petioles
under two different phytohormone regimes was devised. Our data suggest that some of the diffusible factors from the lamina
may be phytohormones, and that the establishment of an endogenous phytohormone gradient in the explants may affect shoot bud
differentiation in this culture system.
Received: 7 April 1998 / Revision received: 8 April 1998 / Accepted: 17 April 1998 相似文献
10.
1 属的起源根据地质历史资料和形态、生态综合分析 ,我们认为在第三纪早期 ,泡桐属中还只有一种 ,到第三纪中新世时 ,才分化成华东泡桐 ( Paulownia kawakamii)和毛泡桐 ( P.tomentosa)两个种。在第三纪地层中 ,毛泡桐叶的化石在我国山东、法国、捷克和北美都有发现 ,特别是同一时期在日本歧阜县发现类似华东泡桐直径 1 55cm的矽化树干 ,这样的大树 ,在现存的华东泡桐中是从未见过的 ,这说明在当时的环境下 ,华东泡桐是适应生长的。另外 ,在形态上两种泡桐均为树形较小、叶宽有角、叶缘有锯齿、宽大圆锥花序、深裂的花萼、较小的果实和种… 相似文献