全文获取类型
收费全文 | 144篇 |
免费 | 17篇 |
国内免费 | 4篇 |
专业分类
林业 | 30篇 |
农学 | 7篇 |
9篇 | |
综合类 | 16篇 |
农作物 | 22篇 |
水产渔业 | 2篇 |
畜牧兽医 | 75篇 |
园艺 | 1篇 |
植物保护 | 3篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 6篇 |
2020年 | 9篇 |
2019年 | 9篇 |
2018年 | 9篇 |
2017年 | 8篇 |
2016年 | 3篇 |
2015年 | 6篇 |
2014年 | 7篇 |
2013年 | 8篇 |
2012年 | 11篇 |
2011年 | 5篇 |
2010年 | 7篇 |
2009年 | 8篇 |
2008年 | 9篇 |
2007年 | 2篇 |
2006年 | 8篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 6篇 |
2002年 | 6篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 5篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1987年 | 3篇 |
1986年 | 1篇 |
排序方式: 共有165条查询结果,搜索用时 31 毫秒
1.
2.
《Veterinary parasitology》2015,207(1-2):49-55
Natural anti-parasitic compounds in plants such as condensed tannins (CT) have anthelmintic properties against a range of gastrointestinal nematodes, but for other helminths such effects are unexplored. The aim of this study was to assess the effects of CT from three different plant extracts in a model system employing the rat tapeworm, Hymenolepis diminuta, in its intermediate host, Tenebrio molitor. An in vitro study examined infectivity of H. diminuta cysticercoids (excystation success) isolated from infected beetles exposed to different concentrations of CT extracts from pine bark (PB) (Pinus sps), hazelnut pericarp (HN) (Corylus avellana) or white clover flowers (WC) (Trifolium repens), in comparison with the anthelmintic drug praziquantel (positive control). In the in vitro study, praziquantel and CT from all three plant extracts had dose-dependent inhibitory effects on cysticercoid excystation. The HN extract was most effective at inhibiting excystation, followed by PB and WC. An in vivo study was carried out on infected beetles (measured as cysticercoid establishment) fed different doses of PB, HN and praziquantel. There was a highly significant inhibitory effect of HN on cysticercoid development (p = 0.0002). Overall, CT showed a promising anti-cestodal effect against the metacestode stage of H. diminuta. 相似文献
3.
桉木抽出物中多酚化合物的特性研究 总被引:10,自引:0,他引:10
采用化学分析和光谱分析相结合的方法,从制浆造纸的角度,重点对雷林一号桉木的多酚化合物的特性进行了研究。结果表明:幼龄材的抽出物含量较少,适宜于制浆的采伐期为5~7年。15年生雷林一号桉木心材中的多酚类化合物以水解单宁为主(占原料的5.98%),其次为缩合单宁(1.91%)。稀碱预处理桉木,可除去大部分多酚类化合物。存放过久的桉木中多酚化合物大部分变成‘黄粉’,既不溶于水也不溶于丙酮,只溶于稀碱或亚硫酸钠。桉木制浆前采用碱预处理可减轻多酚化合物对制浆产生的不良影响。 相似文献
4.
Fumiaki Nakatsubo Kenichi Enokita Koji Murakami Keizo Yonemori Akira Sugiura Naoki Utsunomiya Suranant Subhadrabandhu 《Journal of Wood Science》2002,48(5):414-418
The structural variety of the condensed tannins (proanthocyanidins) in the fruits of 16Diospyros species are reported. Eleven species contained condensed tannins mostly consisting of a mixture of catechin (CA) and gallocatechin (GCA) repeating units; the other five species did not. The GCA content in the CA-GCA total varied from 0.3% to 84.6%. The number of esterified gallic acid per one flavan repeating unit (degree of galloylation, DG) ranged from 0.01 to 0.89. The GCA content was found to be proportional to the DG values. Thus, 16Diospyros species tested may be classified into five groups by the analytical data of their condensed tannins. It may be interesting to compare their structural characteristics with those of the condensed tannins in other fruits, leaves, woods, and barks from the viewpoint of their biosynthesis and function in the plants.Part of this paper was presented at the 46th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1995 相似文献
5.
6.
Condensed tannins (CTs) are a major component of litter inputs, but little is known about the effects of tannin structural variations on soil biological processes and organic matter development. Four different CTs extracted from balsam fir, western red cedar, kalmia and black spruce were added to Corsican pine litter and subsequently incubated for 16 weeks in order to investigate the effect of the B ring hydroxylation pattern on C, N and P transformations. While for C mineralization the chain length and stereochemistry of the CTs seemed to be a more important parameter, net N and P mineralization rates were clearly reduced compared with non-amended litter. With regard to the B ring hydroxylation, the prodelphinidin (PD) CTs having predominantly three hydroxy groups at the B ring (balsam fir and western red cedar) exhibited significantly lower mineralization rates than the procyanidin (PC) CTs having two OH groups (kalmia and black spruce). The same was true for net nitrification, but this process was only slightly affected by the CTs. Although based on only four CTs, this study indicates that B ring hydroxylation is an important variable determining net N and P mineralization rates. Our results support previous suggestions that PD tannins bind to or react more strongly with soil organic matter. Therefore, more than PC tannins, they reduce the availability of organic N for mineralization as well as their own detectability by standard methods for soil CT. 相似文献
7.
8.
植物单宁对烟草花叶病毒的抑制活性 总被引:5,自引:2,他引:5
测试了从11种植物提取的单宁对烟草花叶病毒(TMV)的抑制活性.结果表明:(1)任一植物的单宁质量浓度为5.000或2.500mg·mL-1时,与TMV混合10min后接种,其抑制率均达80%以上.(2)单宁质量浓度为5.000mg·mL-1时,与TMV混合后立即接种,其抑制率也均达80%以上,表明单宁与病毒粒体作用时间很短.(3)TMV与单宁混合,透析3d后,可恢复大部分侵染力;混合3d但未作透析处理,与混合10min的处理相比,抑制率下降,表明部分植物的单宁体外稳定性可能较差,与TMV粒体作用能力下降.(4)这11种植物的单宁对TMV体内抑制复制效果不明显.(5)大飞扬、杠板归、虎杖3种植物的单宁,在接种前先喷施心叶烟再接种TMV,可抑制病毒的初侵染;在接种前先喷施普通烟草K326再接种TMV,烟株发病期推迟3-8d. 相似文献
9.
This study explores the chemical composition, buffer N solubility, in vitro ruminal N degradability and in vitro ruminal biological activity of tannins in leaves from Gliricidia sepium, Leucaena leucocephala, Morus alba and Trichanthera gigantea trees. These tree leaves are a potential protein source for ruminants, but their site‐influenced nutritive value is largely unknown. Leucaena leucocephala leaves had the highest N content (42.1 g/kg DM), while T. gigantea leaves had the least (26.1 g/kg DM). Leucaena leucocephala had the highest buffer solubility index (20%), while 10% of the total N in leaves of the other three species was soluble. The rapidly fermentable N fraction ‘a’ was highest in M. alba leaves (734.9 g/kg DM) and least in T. gigantea leaves (139.5 g/kg DM). The rate of fermentation (c) was highest for M. alba (7%/hours) leaves. No significant correlations were recorded between buffer solubility index of N and in vitro ruminal N degradability parameters: a, b, and c. The highest response to tannin inactivation using polyethylene glycol, in terms of percentage increase in 36‐hours cumulative gas production, was recorded in M. alba (39%) and T. gigantea (38%) leaves. It was concluded that buffer solubility of N is not a good indicator of ruminal N degradation in the leaves of these tree species. Leaves of M. alba could be more valuable as a source of rapidly fermentable N when animals are offered low‐protein, high‐fibre diets compared with other tree species evaluated in the current study. However, when feeding M. alba leaves, the role of tannins must be considered because these secondary plant compounds showed significant in vitro ruminal biological activity. 相似文献
10.
The literature about tannins, polyphenolic secondary metabolites of plants, with both beneficial and adverse function according to their concentration and chemical structure, is vast and often conflicting. Tannins in forages have often been described as antinutritional factors, but this review aims to update information on beneficial effects on animals and the environment. Although research on the relation between tannins and animal production and health, for example, dry‐matter intake, digestibility, rumen fermentation and diseases, has mainly focused on condensed tannins, this review also discusses potential benefits from the use of hydrolysable tannins as a feed additive. Attention is given to the use of tannins in the mitigation of methane emissions from ruminants in forage‐based feeding systems and as a natural and ecologically friendly resource for improvement of nutrient utilization and environmental sustainability in meat and dairy farming. 相似文献