全文获取类型
收费全文 | 96篇 |
免费 | 15篇 |
国内免费 | 6篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 1篇 |
2014年 | 7篇 |
2013年 | 8篇 |
2012年 | 2篇 |
2011年 | 3篇 |
2010年 | 6篇 |
2009年 | 4篇 |
2008年 | 9篇 |
2007年 | 12篇 |
2006年 | 4篇 |
2005年 | 9篇 |
2004年 | 2篇 |
2003年 | 10篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1992年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有117条查询结果,搜索用时 16 毫秒
1.
利用乙醇沉淀法提取蔓茎堇菜Viola diffusa和柔毛堇菜V. principis多糖并分别进行抑菌及抗氧化试验。结果表明,蔓茎堇菜和柔毛堇菜多糖提取率分别为7.0%和8.3%。不同倍数体积无水乙醇沉淀提取的多糖抑菌和抗氧化能力不同。抑菌效果显示,蔓茎堇菜多糖对大肠杆菌和枯草芽孢杆菌的抑菌圈分别可达8.46 mm和8.59 mm,柔毛堇菜对大肠杆菌和枯草芽孢杆菌的抑菌圈均可达9.13 mm,但两种堇菜多糖对黑曲霉和啤酒酵母未呈现抑制活性;抗氧化研究发现,蔓茎堇菜多糖抗氧化活性为243.64 U·mL-1,柔毛堇菜多糖抗氧化活性为411.78 U·mL-1。由此可见,无论是抑菌还是抗氧化活性方面,柔毛堇菜极显著优于蔓茎堇菜(P <0.01)。蔓茎堇菜和柔毛堇菜多糖都具有一定的抑菌抗氧化活性,均可作为食药两用植物资源进行开发利用。 相似文献
2.
以2份角堇与4份大花三色堇自交系为试验材料,采用染色体常规压片方法,观察和分析了它们的细胞染色体数目、相对长度、平均臂比等核型指标,以明确两种植物细胞学特点,为分类以及育种提供理论依据。结果表明:(1)2份角堇自交系染色体数目均为2n=2x=26,染色体基数为x=13,染色体核型公式分别为2n=2x=26=8m+12sm+6st、2n=2x=26=4m+16sm+6st,核型不对称系数为67.20%~70.10%,核型分类均属于3B。(2)4份大花三色堇自交系均为四倍体,其中2份(EYO-1-2-1-4、DSRFY-1-1-2)染色体数目为44,核型公式为2n=4x=44=4m+16sm+6st、2n=4x=44=16m+24sm+4st;2份(G10-1-3-1-4、XXL-YB-1-1-1-1)染色体数目为48,核型公式分别为2n=4x=48=8m+20sm+20st、2n=4x=48=4m+36sm+8st,核型不对称系数为66.74%~71.77%,核型分类属于2B、3B。 相似文献
3.
Benjamin Carbonne David A. Bohan Alice Charalabidis Sandrine Petit 《Agricultural and Forest Entomology》2019,21(4):396-406
- Carabid beetles may play a role in the regulation of arable weeds, when seed predation is directly density‐dependent and consumption increases more than proportionally with seed density.
- We quantified the effect of seed and carabid density on consumption by two carabid species (Poecilus cupreus and Harpalus affinis) of the weed species Taraxacum officinale and Viola arvensis. For each pairing of carabid and weed species, we quantified per capita seed mortality (PCSM) over 72 h under combinations of low and high densities of carabids and seeds, aiming to assess whether per capita consumption increased more or less than proportionally with seed density.
- We tested three hypotheses: (i) PCSM is constant as seed availability increases; (ii) for a fixed seed density, PCSM decreases with increasing numbers of carabid conspecifics; and (iii) the response of PCSM changes with the interaction between seed and carabid density.
- Without intraspecific competition, we detected a seed density‐independent predation effect, which became inverse density‐dependent over time. At similar seed densities, the presence of conspecific carabids did not affect PCSM, although it led to a faster shift towards inverse density dependence in T. officinale.
- The findings of the present study suggest that a sufficiently large carabid numerical response might lead to direct predation density‐dependence.
4.
5.
THERESA M. CULLEY 《Molecular ecology resources》2005,5(4):882-884
Viola pubescens is a perennial herb with a mixed mating system involving the production of both open, chasmogamous flowers and closed, cleistogamous flowers. Using a nonradioactive protocol, 12 microsatellite primers that amplified loci with perfect and imperfect repeats were developed in the species. As examined in five populations of V. pubescens using multiplex reactions, all loci exhibited polymorphism with an average of 5.4 alleles. Most primers also amplified in 12 additional Viola species and one cultivar, revealing the possibility of wide applicability across the genus. This is the first known report of microsatellite loci developed in Viola and the Violaceae. 相似文献
6.
Viola mirabilis is abundant in Estonia; Viola elatior is rare. We tested whether these species differ in their competitive responses to a common grass. We used a pot experiment in which individuals of each violet species grew with 0, 2, 4, or 8 individuals of Festuca ovina in natural soil. The response patterns of shoot and root mass and leaf numbers of the two species were similar: the biomass and leaf number of both violet species decreased with increasing grass density. The decrease of root mass of the rare V. elatior was significantly greater, and the decrease of leaf number tended to be greater, than that of the common V.␣mirabilis. We conclude that the stronger competitive response of V. elatior compared to V. mirabilis might be one reason behind its lower regional and local abundance. 相似文献
7.
8.
Hybridization between plant species occurs frequently but hybrids are often restricted to ecotones or disturbed habitats. In this study we show that introgressive hybrids between the tetraploid Viola riviniana and the diploid V. reichenbachiana invaded pine forests of the Dübener Heide (central Germany), an area affected by calcareous pollutants. The spread of these violet populations was correlated with the impact of pollution on habitat conditions. We compared morphology, cytology and random amplified polymorphic DNA (RAPD) bands among six Viola populations from the Dübener Heide and three populations of each pure species. RAPD analysis using 12 primers revealed 141 scorable bands. We considered bands as species specific if they occurred in at least 75% of the plants in one pure violet species but in none of the other. Seven bands were specific to V. riviniana and 11 bands were specific to V. reichenbachiana . Two plants of a V. reichenbachiana population were identified as hybrids. Of the Viola populations from the Dübener Heide, one was diploid and could be classified as V. reichenbachiana by morphology and RAPD markers. However, the majority of the Dübener Heide populations were tetraploid, and of a more variable morphology than V. riviniana and V. reichenbachiana , showing different combinations of intermediate characters, characters of the pure species and extreme characters. Despite their overall genetic similarity to V. riviniana , these plants could be identified as introgressive hybrids between V. riviniana and V. reichenbachiana by species-specific RAPD bands. Therefore, we propose that recurrent hybridization and backcrossing resulted in novel genotypes adapted to the changed environment of polluted pine forests. 相似文献
9.
10.
Formulation of some microbial herbicides in emulsions of vegetable oil can significantly reduce their dependency on long dew periods to allow infection and control of the host weed. Examination of leaves of Viola arvensis , by a range of microscopy techniques, after spraying with an oilin-water emulsion formulation of the potential microbial herbicide Mycocentrospora acerina , suggests that the effect arises as a result of inversion of water into both oil droplets on the leaf surface and oil that penetrates into the leaf tissue. This oil probably mixes with aqueous components from the leaf tissue and, in doing so, forms an invert emulsion. Wesuggest that this supplies the water required by the fungus to initiate and sustain growth so that infection can result. 相似文献