全文获取类型
收费全文 | 113篇 |
免费 | 4篇 |
国内免费 | 5篇 |
专业分类
林业 | 28篇 |
农学 | 7篇 |
8篇 | |
综合类 | 52篇 |
农作物 | 13篇 |
水产渔业 | 1篇 |
畜牧兽医 | 9篇 |
园艺 | 4篇 |
出版年
2022年 | 1篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 4篇 |
2013年 | 5篇 |
2012年 | 8篇 |
2011年 | 14篇 |
2010年 | 3篇 |
2009年 | 12篇 |
2008年 | 7篇 |
2007年 | 2篇 |
2006年 | 4篇 |
2005年 | 3篇 |
2004年 | 4篇 |
2003年 | 2篇 |
2001年 | 4篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 6篇 |
1995年 | 6篇 |
1994年 | 2篇 |
1993年 | 7篇 |
1992年 | 3篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有122条查询结果,搜索用时 15 毫秒
1.
采用分段浸取新工艺是黑荆树皮单宁提取的关键技术。即以平转型连续最提为常压段、以水平渗滤(进、出)垂直釜为加压段,经生产考核,其工艺先进、运行可靠、经济合理、操作简便,产品质量稳定。 相似文献
2.
3.
儿茶素对蝴蝶兰叶片离体培养褐变发生的影响 总被引:1,自引:0,他引:1
用0.3 g/L儿茶素处理蝴蝶兰叶片外植体,在MS+3 mg/L 6-BA(pH 5.8)培养基上培养4 d,外植体褐变率高于对照227.6%.用香草醛-盐酸溶液染色反应法发现鞣质分布在维管束和细胞间隙.叶片剪切的外植体(培养0 d)鞣质含量较高,培养4 d降低,8 d后再升高.儿茶素处理的外植体鞣质含量明显高于对照.在培养期间,儿茶素处理的外植体PPO、POD和PAL活性高于对照外植体,其中POD活性在第8天达到最大值,PPO和PAL活性在培养第12天达到高峰. 相似文献
4.
从12种中国药用植物中分离到113个单宁及多酚类化合物,经波谱分析及化学方法鉴定了它们的结构。其中19个为新化合物。 相似文献
5.
Treatment of wheat straw using tannase and white-rot fungus to improve feed utilization by ruminants
Background
Current research to enrich cattle feed has primarily focused on treatment using white rot fungi, while there are scarce reports using the enzyme tannase, which is discussed only in reviews or in the form of a hypothesis. In this context, the aim of the present study was to evaluate the effect of tannase on wheat straw (WS) and also the effect of lyophilized tannase at concentrations of 0.1%, 0.2%, and 0.3% (w/w) on WS followed by fermentation with Ganoderma sp. for 10 d and compared in relation to biochemical parameters, crude protein (CP) content, and nutritional value by calculating the C/N ratio in order to improve the nutritional value of cattle feed.Results
Penicillium charlesii, a tannase-producing microorganism, produced 61.4 IU/mL of tannase in 54 h when 2% (w/v) tannic acid (TA) was initially used as a substrate in medium containing (% w/v) sucrose (1.0), NaNO3 (1.0), and MgSO4 (0.08 pH, 5.0) in a 300-L fermentor (working volume 220 L), and concomitantly fed with 1.0% (w/v) TA after 24 h. The yield of partially purified and lyophilized tannase was 5.8 IU/mg. The tannin-free myco-straw at 0.1% (w/w) tannase showed 37.8% (w/w) lignin degradation with only a 20.4% (w/w) decrease in cellulose content and the in vitro feed digestibility was 32.2%. An increase in CP content (up to 1.28-fold) along with a lower C/N ratio of 25.0%, as compared to myco-straw, was obtained.Conclusions
The use of tannin-free myco-straw has potential to improve the nutritional content of cattle feed. This biological treatment process was safe, eco-friendly, easy to perform, and was less expensive as compared to other treatment methods. 相似文献6.
单宁用于带锈钢铁防蚀处理的研究 总被引:3,自引:1,他引:2
用栲胶及其增纯产物和相应的单宁-铁螯合物代替工业单宁酸成功地用于带锈钢铁的抗蚀处理,研究了处理剂的配方、配制方法,并对其性能进行了测试,指标均达到或超过了工业单宁酸。 相似文献
7.
[目的]获得可产生涩柿单宁酶的微生物,并对其鉴定。[方法]微生物在以涩柿为培养基上自然生长,进行划线分离,获得纯种菌株。将菌株接种于溴酚蓝培养基上,选取变色圈较大的8个菌株,进行COD去除率和单宁耐受力试验,选取COD去除率高、单宁耐受力强的菌株,使用形态学观察法进行菌种鉴定。[结果]获得可产生涩柿单宁酶的菌株,初步鉴定为黑曲霉。[结论]利用该方法,可获得产生涩柿单宁酶的黑曲霉,其COD去除率高、单宁耐受力强,有成为工程菌株的潜力。 相似文献
8.
络合滴定黑荆栲胶中单宁含量的新方法 总被引:8,自引:0,他引:8
利用单宁分子结构中酚羟基能与Pb^2+络合的原理,以K2CrO4为指示剂,PAM作终点增敏剂,用Pb^2+标准溶液络合滴定黑荆栲胶中单宁的新方法。该法比皮粉法快速、准确。 相似文献
9.
Andreas B. Wolff Maria Sidirelli Constantinos Paradellis Kiriakos Kotzabasis 《Biology and Fertility of Soils》1995,20(4):249-252
The relationship between soil acidity and polyamine (putrescine, spermidine, spermine) concentrations in roots was evaluated and compared to (1) nodule numbers in common beans and (2) tannin concentrations in roots. Six Phaseolus vulgaris cultivars were grown in pots in a greenhouse in soil at pH 4.5 or 5.5 and inoculated with Rhizobium leguminosarum bv. phaseoli strains. At pH 4.5 nodule numbers were strongly reduced but polyamine concentrations were 50% higher than at pH 5.5. At both pH levels putrescine and spermidine were the dominant polyamines, while the concentration of spermine was less than half of the other two. There was also a cultivar effect on the polyamine concentration, but this was much less pronounced than the pH effect. By 22 days after planting the uninoculated control plants had about 13% lower levels of polyamines than the inoculated plants. The concentrations of putrescine, spermidine, and spermine were negatively correlated with nodule numbers, but positively correlated with the root tannin content. There were no significant correlations with either root or plant dry weight. 相似文献
10.
The aims of this study were to determine the degree of lignin degradation and to investigate changes in the chemical composition of the organic matter in the forest floor in an N fertilized Norway spruce forest soil. Needle litter and mor humus were collected from the field experiment at Skogaby in southern Sweden (56°33′N; 13°13′E). The spruce stand had been fertilized for 11 years with 100 kg N ha−1 yr−1 as (NH4)2SO4. The degree of lignin degradation was determined with alkaline CuO oxidation followed by HPLC analysis. The chemical composition of the organic matter was characterized by CPMAS 13C NMR. Tannin was specifically analyzed using dipolar dephasing CPMAS 13C NMR and the N distribution was studied by CPMAS 15N NMR.The C-to-N ratios in the fertilized Oi and Oe layers were significantly lower than in the unfertilized layers (24 compared to 34 and 23 compared to 27, respectively). Neither the sum of the CuO oxidation products (Vanillyls+Syringyls+Cinnamyls expressed as VSC) nor the acid-to-aldehyde ratio ((Ac/Al)V) showed any significant treatment effects. The content of aromatic C (including phenolic C) was significantly lower in the unfertilized than in the fertilized Oi layer (18 versus 21%). In the unfertilized soil, VSC was positively correlated (r=+0.63, p<0.05) with the C-to-N ratio, whereas the phenolic C content was negatively correlated (r=−0.61, p<0.05). The tannin index showed a tendency of increasing from Oi to Oe layers in both treatments. Most of the organic N was found as amide-N, whereas no heterocyclic N was detected. We have not been able to show any major C structural changes due to N fertilization. We suggest that the significantly higher content of aromatic and phenolic C in the fertilized Oi layer is due to an initial stimulation of the microbial community. 相似文献