全文获取类型
收费全文 | 496篇 |
免费 | 29篇 |
国内免费 | 92篇 |
出版年
2024年 | 5篇 |
2023年 | 9篇 |
2022年 | 19篇 |
2021年 | 32篇 |
2020年 | 13篇 |
2019年 | 33篇 |
2018年 | 19篇 |
2017年 | 23篇 |
2016年 | 26篇 |
2015年 | 25篇 |
2014年 | 25篇 |
2013年 | 38篇 |
2012年 | 27篇 |
2011年 | 26篇 |
2010年 | 24篇 |
2009年 | 22篇 |
2008年 | 25篇 |
2007年 | 17篇 |
2006年 | 18篇 |
2005年 | 19篇 |
2004年 | 16篇 |
2003年 | 14篇 |
2002年 | 7篇 |
2001年 | 7篇 |
2000年 | 9篇 |
1999年 | 8篇 |
1998年 | 11篇 |
1997年 | 14篇 |
1996年 | 9篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 7篇 |
1991年 | 9篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1979年 | 2篇 |
排序方式: 共有617条查询结果,搜索用时 171 毫秒
61.
Twelve anthocyanins (1-12) were isolated from the red flowers of Camellia hongkongensis Seem. by chromatography using open columns. Their structures were elucidated on the basis of spectroscopic analyses, that is, proton-nuclear magnetic resonance, carbon 13-nuclear magnetic resonance, heteronuclear multiple quantum correlation, heteronuclear multiple bond correlation, high resolution electrospray ionization mass and ultraviolet visible spectroscopies. Out of these anthocyanins, a novel acylated anthocyanin, cyanidin 3-O-(6-O-(Z)-p-coumaroyl)-β-galactopyranoside (6), two known acylated anthocyanins, cyanidin 3-O-(6-O-(E)-p-coumaroyl)-β-galactopyranoside (7) and cyanidin 3-O-(6-O-(E)-caffeoyl)-β-galactopyranoside (8), and three known delphinidin glycosides (10-12) were for the first time isolated from the genus Camellia. Furthermore, pigment components in C. japonica L., C. chekiangoleosa Hu and C. semiserrata Chi were studied.The results indicated that the distribution of anthocyanins was differed among these species. Delphinidin glycoside was only detected in the flowers of C. hongkongensis, which is a special and important species in the section Camellia. Based on the characterization of anthocyanins in the section Camellia species, there is a close relationship among these species,and C. hongkongensis might be an important parent for creating new cultivars with bluish flower color. 相似文献
62.
《Journal of Plant Interactions》2013,8(3):169-174
Abstract A psychrotolerant, halotolerant and alkalophilic yeast was isolated from fermented leaves of Camellia sinensis Kuntze, the tea plant. The yeast strain, named Tea-Y1, was both phenotypically and genotypically identified as belonging to the species Debaryomyces hansenii. This assignment was confirmed by scanning and transmission electron microscopy. The analysis of growth curves demonstrated the ability this yeast strain to grow in a temperature range between 4°C and 28°C, with an optimum of 23°C. The ecology of this yeast in the C. sinensis phyllosphere, as well as its possible role in tea fermentation and storage, with particular reference to iced tea, are discussed. 相似文献
63.
普通油茶叶绿体基因组密码子偏好性分析 总被引:1,自引:0,他引:1
为了利用叶绿体基因工程技术改良普通油茶的重要经济性状,该研究以普通油茶叶绿体全基因组序列为材料,从中筛选出51条长度大于300 bp且以ATG起始的非重复CDS(Coding DNA Sequence)为对象,利用CodonW软件分析其密码子偏好性。结果表明:密码子第三位GC含量为27.55%,ENC范围在35.23~56.67之间,平均值为46.09;RSCU值大于1.00的密码子数目为30个,其中29个第三位碱基以U或A结尾;中性绘图表明GC12与GC3的相关系数为0.143,相关性不显著,回归系数为0.0573;频数分布显示,55%基因的ENC比值集中分布在0~0.1,25%基因的ENC比值分布在0.1~0.2之间;对应分析结果表明,第一向量轴占10.12%的差异,第二向量轴占9.36%的差异,其余两轴分别占7.97%和7.46%,前4轴累计差异为34.91%。中性绘图、ENC-plot和对应性分析均表明普通油茶叶绿体基因密码子偏好受突变作用,更多受选择的影响。最终取高表达优越密码子和高频密码子共有的CUU、AUU、GUU、GUA、UAA、CAA、AAA、GAC、GAA、CCU、ACU、GCU、GCA、UGU、CGU、AGU、UUG、GGU等18个密码子作为最优密码子。该研究结果为利用叶绿体基因工程技术改良普通油茶重要经济性状奠定了基础。 相似文献
64.
该研究基于茶树转录组数据,从茶树‘龙井43’cDNA中克隆获得茶树CsBAP1基因,对其蛋白质序列特征和基因表达模式以及CsBAP1在茶树不同组织、不同激素处理及不同逆境胁迫下的表达水平进行荧光定量检测。结果显示:(1)克隆得到的茶树CsBAP1基因开放阅读框长度为543 bp,编码180个氨基酸;CsBAP1蛋白为亲水性蛋白,理论相对分子质量为19 398 Da,理论等电点为9.30,含有保守的Ca2+依赖性的C2结构域;茶树CsBAP1蛋白二级结构由8.89%的α 螺旋、7.78%的β 转角、35.56%的β 折叠和47.78%的随机卷曲组成;三级结构分析结果显示,CsBAP1包括螺旋和折叠结构,与二级结构吻合。(2)荧光定量分析结果显示, CsBAP1基因在茶树的花、花蕾、幼叶、老叶和成熟叶中均有表达,且在老叶中的表达量最高;外源施用ABA、IAA、MeJA、GA3以及SA均能够抑制茶树CsBAP1基因的表达;在高温(38 ℃)、低温(4 ℃)、干旱(200 g·L-1 PEG)、高盐(200 mmol·L-1 NaCl)胁迫下,CsBAP1的表达量均有所上调,且不同时间段的表达存在显著差异。该研究为进一步研究茶树CsBAP1基因的功能奠定了基础。 相似文献
65.
Deep eutectic solvents used as extraction solvent for the determination of flavonoids from Camellia oleifera flowers by high‐performance liquid chromatography
下载免费PDF全文
![点击此处可从《Phytochemical analysis : PCA》网站下载免费的PDF全文](/ch/ext_images/free.gif)
66.
Yizhang Xie Shengbo Ge Shuaicheng Jiang Zhenling Liu Liang Chen Lishu Wang Juntao Chen Lichun Qin Wanxi Peng 《Saudi Journal of Biological Sciences》2018,25(2):234-236
This study aims to present an integrated process that can be used to produce biomedical and biological active components from the fruit shell of Camellia oleifera Abel. Through the Foss method, Aldehyde, acid compounds, acyl and alcohol compounds account for 22.7, 15.93, 0.24 and 61.13% of the extractives which were extracted from Camellia oleifera fruit shell by methanol solvents. Furfural, Pyrazole-4-carboxaldehyde, 1-methyl- and 5-Hydroxymethylfurfural account for 4.74, 1.22 and 58.78% of the extractives which were extracted from the fruit shell of Camellia oleifera Abel by ethanol solvents. Aldehyde, acid and amine compounds account for 5.01, 56.18 and 7.20% of the extractives which were extracted from the fruit shell of Camellia oleifera Abel by ethyl acetate solvents. The extractives of fresh flesh of bayberry were rich in rare drug, biomedical and biological activities. 相似文献
67.
Diversity and genetic differentiation among populations of Indian and Kenyan tea (Camellia sinensis (L.) O. Kuntze) revealed by AFLP markers 总被引:1,自引:0,他引:1
S. Paul F. N. Wachira W. Powell R. Waugh 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,94(2):255-263
AFLP markers were successfully employed to detect diversity and genetic differentiation among Indian and Kenyan populations
of tea (Camellia sinensis (L.) O. Kuntze). Shannon's index of diversity was used to partition the total phenotypic variation into between and within
population components. On average, most of the diversity was detected within populations, with 79% of the variation being
within and 21% being between populations of Indian and Kenyan tea. A dendrogram constructed on the basis of band sharing distinctly
separated the three populations of tea into China type (sinensis), Assam type (assamica) and Cambod type (assamica ssp. lasiocalyx) in a manner consistent with the present taxonomy of tea, the known pedigree of some of the genotypes and their geographical
origin. Principal coordinate (PCO) analysis grouped Assam genotypes both from India and Kenya supporting the suggestion that
the Kenyan clones have been derived from collections made in this region. The China types were more dispersed on the PCO plot
which is a reflection of wider genetic variation. As would be expected, clones collected from the same region exhibited less
overall genetic variation. AFLP analysis discriminated all of the tested genotypes from India and Kenya, even those which
cannot be distinguished on the basis of morphological and phenotypic traits.
Received: 2 May 1996 / Accepted: 14 June 1996 相似文献
68.
About 85% of the fatty acids liberated during the manufacture of black tea can be attributed to autolysis of 4 major polar lipid classes in tea leaf tissue, phosphatidylcholine, monogalactosyldiglyceride, digalactosyldiglyceride and phosphatidylethanolamine. Linolenic, linoleic and palmitic acids are the principal fatty acids released from these lipids and they all undergo further degradation. Linolenic acid (60% of fatty acids released) is derived mainly from galactolipids and thus the upper limit of release is dependent on the chloroplast maturity and content of the leaf tissues. Lipid breakdown is complete after 2 hr fermentation and, as there appears to be no accumulation of long chain fatty acid intermediates, it is probable that volatile production has also ceased at this time. 相似文献
69.
Sharma Madhu Sood Anil Nagar P.K. Prakash Om Ahuja Paramvir Singh 《Plant Cell, Tissue and Organ Culture》1999,58(2):111-118
Micropropagation of tea (Camellia sinensis (L.) O. Kuntze) has been widely attempted but commercial exploitation of this method is limited by heavy losses during the
hardening procedures. In the present study, optimization of time of harvesting (spring and early summer) of microshoots, shoot
size, soil pH (4.0–6.4), plant growth regulator treatment (IBA; 500 mg l-1, 30 min) CO2 (9.09/10×10−5 mol l-1 to 10.22/10×10-5 mol l-1 and 20/11×10−5 mol l-1 to 80/13×10−7 mol l-1) enrichment and light (15 μ mol m-2 s-1) conditions in specially designed hardening chambers, made a significant impact on the percent of success for hardening.
Following the standardized procedure, up to 71.6% root induction and 73% survival could be achieved. Successful field transfer
was also accomplished.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
70.