全文获取类型
收费全文 | 90篇 |
免费 | 22篇 |
国内免费 | 39篇 |
专业分类
151篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2018年 | 5篇 |
2017年 | 4篇 |
2016年 | 5篇 |
2015年 | 8篇 |
2014年 | 3篇 |
2013年 | 4篇 |
2012年 | 3篇 |
2011年 | 11篇 |
2010年 | 7篇 |
2009年 | 7篇 |
2008年 | 11篇 |
2007年 | 17篇 |
2006年 | 9篇 |
2005年 | 13篇 |
2004年 | 7篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1978年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有151条查询结果,搜索用时 15 毫秒
71.
本文报道采自北京、安徽和云南泽兰属(Eupatorium spp.)叶上的三种真菌,其中有一个新种:泽兰齿梗孢(Scolecobasidium eupatorii Guo,sp.nov.)和一个新组合:藿香蓟假尾孢[Pseudocercospora ageratoides(Ell.& Ev.)Guo,comb.nov.]。新种与Sco-lecobasidium anelii和S.arenarium之区别在于S.anelii分生孢子梗短(35.0μm),分生孢子有纵隔膜,常在隔膜处缢缩;S.arenarium分生孢子的隔膜色泽深,在孢子的一端或两端具黑点。研究的标本收藏在中国科学院微生物研究所真菌标本室(HMAS)。 相似文献
72.
73.
The effect of thermal stress on the antioxidant system was Investigated in two invasive plants, Eupatorlum adenophorum Spreng. and E. odoratum L. The former is sensitive to high temperature, whereas the latter is sensitive to low temperature.Our aim was to explore the relationship between the response of antioxidant enzymes and temperature In the two
Invasive weeds with different distribution patterns in China. Plants were transferred from glasshouse to growth chambers at a constant 25 ℃ for 1 week to acclimatize to the environment. For the heat treatments, temperature was Increased stepwise to 30, 35, 38 and finally to 42 ℃. For the cold treatments, temperature was decreased stepwise to 20, 15,10 and finally to 5 ℃.Plants were kept In the growth chambers for 24 h at each temperature step. In E. adenophorum, the coordinated Increase of the activities of antioxidant enzymes was effective In protecting the plant from the eccumulatlon of active oxygen species (AOS) at low temperature, but the activities of catalase (CAT), guaiacol peroxidase (POD), ascorbate peroxidase (APX),glutathione reductase (GR), and monodehydroascorbate reductase (MDAR) were not accompanied by the Increase of super-oxide dismutase (SOD) during the heat treatments. As a result, the level of lipid peroxidation in E. adenophorum was higher under heat stress than under cold stress. In E. odoratum, however, the lesser degree of membrane damage, as indicated by low monodehydroascorbate content, and the coordinated Increase of the oxygen. Dstoxlfying enzymes were observed in hest-treated plants, but the antioxidant enzymes were unable to operate in cold stress. This indicates that the plants have a higher capacity for scavenging oxygen radicals in heat stress than in cold stress. The different responses of antloxidant enzymes may be one of the possible mechanisms of the differences in temperature sensitivities of the two plant species. 相似文献
74.
Zu YuanGang Gao ChongYang Wang WenJie Yang FengJian Liu Ying Wang Min Zhao YangGuo 《中国科学:生命科学英文版》2007,50(1):22-30
The traditional culture-dependent plate counting and culture-independent small-subunit-ribosomal RNA gene-targeted molecular
techniques, Single-Strand Conformation Polymorphism (SSCP) and terminal Restriction Fragment Length Polymorphism (tRFLP) combined
with 16S rDNA clone library were adopted to investigate the impacts of secretion from Camptotheca acuminata (abbreviated to Ca) roots on the quantities and structure of eukaryotic microbes and bacteria in the rhizosphere, and the
possibility that Ca controls exotic invasive plant Eupatorium adenophorum (Ea). The counting results indicated that the number of bacteria increased in turn in rhizospheres of Ea, Ca-Ea mixed culture
and Ca, while that of eukaryotic microbes decreased. PCR-SSCP profiles showed eukaryotic microbial bands (corresponding to
biodiversity) in rhizosphere of Ea were more complex than those of Ca and CE. Meristolohmannia sp., Termitomyces sp. and Rhodophyllus sp. were the dominant populations in the rhizosphere of Ca. Bacterial terminal restriction fragments (TRFs) profiles showed
no difference among three kinds of rhizospheres, and the sequences of the 16S rDNA clone library from Ca rhizospheres were
distributed in 10 known phyla, in which phylum Proteobacteria were the absolute dominant group and accounted for 24.71% of
the cloned sequences (δ-Proteobacteria accounted for up to 17.65%), and phyla Acidobacteria and Bacteroidetes accounted for
16.47% and 10.59% of the cloned sequences, respectively. In addition, high performance liquid chromatography detected a trace
amount of camptothecin and hydroxycamptothecin in the rhizospheric soil of Ca and CE, but examined neither camptothecin nor
hydroxycamptothecin in rhizospheric soil of Ea. Therefore, invasion and diffusion of Ea evidently depended on distinguishing
the eukaryotic community structure, but not on that of the bacterial pattern. Ca was able to alter the eukaryotic community
structure of invasive Ea by secreting camptothecin and hydroxycamptothecin into rhizospheres, and may benefit the control
of overspread of Ea. This study provided theoretical evidence for rhizospheric microbial aspects on substituting Ca for Ea.
Supported by the Excellent Young Teacher’s Innovation Foundation of Northeast Forestry University to Yang FengJian, the Key
Research Fund of Ministry of Education of China (Grant No. 104191) and the Forestry Noxious Plant Investigation Fund of State
Forestry Administration of China to Zu YuanGang 相似文献
75.
76.
Pei‐Yu Liu Dan Liu Wei‐Huan Li Ting Zhao Françoise Sauriol Yu‐Cheng Gu Qing‐Wen Shi Man‐Li Zhang 《化学与生物多样性》2015,12(10):1481-1515
Eupatorium (family: Compositae), which comprises nearly 1200 species, is distributed throughout tropical America, Europe, Africa, and Asia. Up to now, the reported constituents from the genus Eupatorium involve flavonoids, terpenoids, pyrrolizidine alkaloids, phenylpropanoids, quinonoids, essential oils, and some others, altogether more than 300 compounds. Studies have shown that Eupatorium and its active principles possess a wide range of pharmacological activities, such as cytotoxic, antifungal, insecticidal, antibacterial, anti‐inflammatory, and antinociceptive activities. Currently, effective monomeric compounds or active parts have been screened for pharmacological activities from Eupatorium in vivo and in vitro. Increasing amount of data supports application and exploitation for new drug development. 相似文献
77.
链格孢菌毒素对紫茎泽兰的致病机理 总被引:38,自引:0,他引:38
以叶圆片法分析链格孢菌[Alternaria alternata(Fr.)Keissler]毒素对紫茎泽兰(Eupatorium adenophorum Spreng.)叶组织细胞膜透性、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)和过氧化氢酶(CAT)活性以及丙二醛(MDA)含量的影响,结果表明,链格孢菌毒素使紫茎泽兰叶组织细胞膜透性上升,Na^ 和K^ 渗漏量增加,膜脂过氧化加强,MDA含量上升;链格孢菌毒素处理的紫茎泽兰叶片中POD、APX和CAT的活性均较对照降低。 相似文献
78.
广东土牛膝为菊科泽兰属植物华泽兰(Eupatorium chinense)的干燥根。从其甲醇提取物中共分离得到11个化合物,其中eupatorinA(1)为一新化合物,经波谱学方法鉴定为(threo)-3-O-acetyl-1-(4-hydroxy-3-methoxyphenyl)-2-[4-(3-hydroxy-1-(E)-propenyl)-2,6-dimethoxyphenoxy]propyl-β-D-glucopy-ranoside。已知化合物分别鉴定为(threo)-3-hydroxy-1-(4-hydroxy-3-methoxyphenyl)-2-[4-(3-hydroxy-1-(E)-propenyl)-2,6-dimethoxyphenox-y]-propyl-β-D-glucopyranoside(2),ardisiacrispinA(3),ardisiac-rispinB(4),euparone(5),3-(2,3-dihydroxy-isopen-tyl)-4-hydroxyacetophenone(6),12,13-di-hydroxy-euparin(7),gymnastone(8),N-(2′-hydroxy-tetracosanosyl)-2-amino-1,3,4-trihydroxy-octa-dec-8-(E)-ene(9),stigmasterol(10)和stigmasterol-3-O-β-D-glucopyranoside(11)。化合物2-4为首次从菊科植物,5-8为首次从泽兰属植物中分离得到。 相似文献
79.
西双版纳两种生态特性不同的外来草本植物对生长环境光强的适应策略 总被引:6,自引:1,他引:6
于干热季测定了紫茎泽兰和阳春砂仁叶片比叶重、色素含量、光合能力和叶绿素荧光动力学参数,探讨了它们适应环境光强的策略及其生理生态学机制。36 %光强下砂仁叶片光抑制较明显;10 0 %光强下紫茎泽兰光抑制不严重,光系统 最大光能转换效率和量子效率始终维持在较高水平。随着环境光强的升高,紫茎泽兰最大净光合速率(Pmax)、比叶重、非光化学猝灭系数(N PQ)和单位面积叶片类胡萝卜素含量升高,单位干重叶片叶绿素含量降低。紫茎泽兰能通过形态和生理特性的变化适应大幅度的光强范围,这可能是其表现强入侵性的重要原因之一。强光下紫茎泽兰热耗散并不多,主要通过提高Pmax利用更多的光能来保护光合机构,光系统 反应中心可逆失活也能耗散部分光能。虽然砂仁Pmax也能随生长环境光强的升高而增大,但其值较低,增幅不大,相反其热耗散的增加较多,N PQ较高,白天初始荧光明显低于黎明,表明砂仁主要是通过热耗散来保护光合机构。 相似文献
80.
Characteristics of the microbial community in rhizosphere of <Emphasis Type="Italic">Camptotheca acuminata</Emphasis> cultured with exotic invasive plant <Emphasis Type="Italic">Eupatorium adenophorum</Emphasis> 下载免费PDF全文
Zu YuanGang Gao ChongYang Wang WenJie Yang FengJian Liu Ying Wang Min Zhao YangGuo 《中国科学C辑(英文版)》2007,50(1):22-30
The traditional culture-dependent plate counting and culture-independent small-subunit-ribosomal RNA gene-targeted molecular
techniques, Single-Strand Conformation Polymorphism (SSCP) and terminal Restriction Fragment Length Polymorphism (tRFLP) combined
with 16S rDNA clone library were adopted to investigate the impacts of secretion from Camptotheca acuminata (abbreviated to Ca) roots on the quantities and structure of eukaryotic microbes and bacteria in the rhizosphere, and the
possibility that Ca controls exotic invasive plant Eupatorium adenophorum (Ea). The counting results indicated that the number of bacteria increased in turn in rhizospheres of Ea, Ca-Ea mixed culture
and Ca, while that of eukaryotic microbes decreased. PCR-SSCP profiles showed eukaryotic microbial bands (corresponding to
biodiversity) in rhizosphere of Ea were more complex than those of Ca and CE. Meristolohmannia sp., Termitomyces sp. and Rhodophyllus sp. were the dominant populations in the rhizosphere of Ca. Bacterial terminal restriction fragments (TRFs) profiles showed
no difference among three kinds of rhizospheres, and the sequences of the 16S rDNA clone library from Ca rhizospheres were
distributed in 10 known phyla, in which phylum Proteobacteria were the absolute dominant group and accounted for 24.71% of
the cloned sequences (δ-Proteobacteria accounted for up to 17.65%), and phyla Acidobacteria and Bacteroidetes accounted for
16.47% and 10.59% of the cloned sequences, respectively. In addition, high performance liquid chromatography detected a trace
amount of camptothecin and hydroxycamptothecin in the rhizospheric soil of Ca and CE, but examined neither camptothecin nor
hydroxycamptothecin in rhizospheric soil of Ea. Therefore, invasion and diffusion of Ea evidently depended on distinguishing
the eukaryotic community structure, but not on that of the bacterial pattern. Ca was able to alter the eukaryotic community
structure of invasive Ea by secreting camptothecin and hydroxycamptothecin into rhizospheres, and may benefit the control
of overspread of Ea. This study provided theoretical evidence for rhizospheric microbial aspects on substituting Ca for Ea. 相似文献