首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   300篇
  免费   4篇
  国内免费   2篇
林业   1篇
农学   1篇
基础科学   1篇
  17篇
综合类   117篇
农作物   12篇
水产渔业   2篇
畜牧兽医   140篇
园艺   11篇
植物保护   4篇
  2023年   3篇
  2019年   3篇
  2018年   2篇
  2012年   26篇
  2011年   22篇
  2010年   10篇
  2009年   3篇
  2008年   12篇
  2007年   19篇
  2006年   25篇
  2005年   17篇
  2004年   15篇
  2003年   14篇
  2002年   11篇
  2001年   6篇
  2000年   11篇
  1999年   6篇
  1997年   3篇
  1996年   2篇
  1995年   5篇
  1993年   5篇
  1992年   6篇
  1991年   3篇
  1989年   8篇
  1987年   3篇
  1986年   3篇
  1984年   3篇
  1980年   7篇
  1979年   3篇
  1978年   2篇
  1972年   2篇
  1969年   4篇
  1968年   4篇
  1967年   3篇
  1966年   4篇
  1963年   2篇
  1959年   2篇
  1931年   1篇
  1929年   1篇
  1926年   1篇
  1925年   1篇
  1922年   1篇
  1920年   1篇
  1914年   1篇
  1904年   1篇
  1902年   1篇
  1901年   1篇
  1899年   1篇
  1895年   1篇
  1893年   1篇
排序方式: 共有306条查询结果,搜索用时 15 毫秒
1.
为了探明秦岭地区羊肚菌种质资源现状,调查了秦岭野生羊肚菌分布状况,分离获得了纯培养菌株115株,鉴定为5个种,分别为粗腿羊肚菌、高羊肚菌、尖顶羊肚菌、梯棱羊肚菌和七妹羊肚菌。为秦岭羊肚菌的进一步研究和生产应用打下了基础。  相似文献   
2.
A new diterpenoid, 15-angeloyloxy-16,17-epoxy-19-kauronic acid (1), along with five known metabolites, 16-kauren-19-oic acid (2), 6′-hydroxy-2′,3′,4,4′-tetramethoxychalcone (3), isosakuranetin (4), acacetin (5), and kaempferide (6) was isolated from the organic extracts of the roots of Chromoleana odorata. Their structures were determined by spectroscopic evidences. The structures of 1 and 2 were further confirmed by single-crystal X-ray diffraction studies. Compound 2 exhibited significant α-glucosidase inhibitory and antibacterial activities against Escherichia coli and Bacillus subtilis.  相似文献   
3.
以陕西省洛南县的烟草废弃物(秸秆)为试验材料,白黄侧耳为供试菌株,进行不同配比烟草秆和棉籽壳栽培白黄侧耳比较试验。结果表明:在供试配比范围内,烟草秆所占比例减少,白黄侧耳子实体产量增加;试验配方5栽培的白黄侧耳,菌丝长势好,生物学转化率比配方6(CK)还高;子实体中烟碱含量低于国家食品农药残留标准,重金属镉、汞、铅、砷的含量远低于国家食用菌重金属含量标准。  相似文献   
4.
以香菇菌株238与808为亲本,采用单孢杂交技术,配成异核体菌株,经初筛、复筛及生产鉴定试验,选育而成的香菇新菌株森立17具有菌龄短,出菇温度范围广,适宜陕南秦巴山区秋栽冬出菇等优良性状。  相似文献   
5.
A headspace sorptive extraction (HSSE) in combination with thermal desorption gas chromatography-mass spectrometry (TD-GC-MS) method for the analysis of volatile components (alcohols, esters, carbonyls, acids, phenols and lactones) in wine samples was developed. Extraction conditions such as salting-out effects, sorption time, stirring speed, phase ratio, extraction temperature, and effect of pH were thoroughly evaluated as part of method validation. The method was very sensitive with LODs and LOQs between 50 pg/L to 299 microg/L and 0.2 ng/L to 0.996 microg/L, respectively. Repeatability for all the compounds was between 3 and 22%. The intermediate repeatability was obtained within the acceptable range. Out of 39 volatile compounds selected, 37 were detected and quantitated. The method was found to be simple, cost-effective, sensitive, and use a small sample volume. The method was successfully applied for the routine analysis of 79 young red and white wine samples from various South African districts.  相似文献   
6.
Carrots ( Daucus carota L.) contain phytochemicals including carotenoids, phenolics, polyacetylenes, isocoumarins, and sesquiterpenes. Purple carrots also contain anthocyanins. The anti-inflammatory activity of extracts and phytochemicals from purple carrots was investigated by determining attenuation of the response to lipopolysaccharide (LPS). A bioactive chromatographic fraction (Sephadex LH-20) reduced LPS inflammatory response. There was a dose-dependent reduction in nitric oxide production and mRNA of pro-inflammatory cytokines (IL-6, IL-1beta, TNF-alpha) and iNOS in macrophage cells. Protein secretions of IL-6 and TNF-alpha were reduced 77 and 66% in porcine aortic endothelial cells treated with 6.6 and 13.3 microg/mL of the LH-20 fraction, respectively. Preparative liquid chromatography resulted in a bioactive subfraction enriched in the polyacetylene compounds falcarindiol, falcarindiol 3-acetate, and falcarinol. The polyacetylenes were isolated and reduced nitric oxide production in macrophage cells by as much as 65% without cytotoxicity. These results suggest that polyacetylenes, not anthocyanins, in purple carrots are responsible for anti-inflammatory bioactivity.  相似文献   
7.
Buckwheat (Fagopyrum esculentum Moench) protein (BWP) exhibits hypocholesterolemic activity in several animal models by increasing fecal excretion of neutral and acidic sterols. In the current study, the ability of BWP to disrupt micelle cholesterol solubility by sequestration of cholesterol was investigated. When BWP (0.2%) was incubated with cholesterol and micelle lipid components prior to micelle formation, cholesterol solubility was reduced 40%. In contrast, cholesterol solubility was not decreased when BWP (0.2%) was incubated after micelle formation and incorporation of soluble cholesterol. Buckwheat flour, from which BWP was derived, had no significant effect on cholesterol solubility. Cholesterol uptake in Caco-2 cells from micelles made in the presence of BWP (0.2%) was reduced by 47, 36, 35, and 33% when compared with buckwheat flour, bovine serum albumin, casein, and gelatin, respectively. Reduction in cholesterol uptake in Caco-2 cells was dose-dependent, with maximum reductions at 0.1-0.4% BWP. In cholesterol-binding experiments, 83% of the cholesterol was associated with an insoluble BWP fraction, indicating strong cholesterol-binding capacity that disrupts solubility and uptake by Caco-2 cells.  相似文献   
8.
From the leaves of barley, Hordeum vulgare, one new flavone C-glucoside and three known flavone glucosides were isolated and characterized by (1)H and (13)C NMR and MALDI-TOF-MS. The novel flavone C-glucoside was isovitexin 7-O-beta-[6' "-O-(E)-p-coumaroyl]glucoside (6' "-coumaroylsaponarin), and the known compounds were isovitexin 7-O-beta-[6' "-O-(E)-feruloyl]glucoside, isoorientin 7-O-beta-[6' "-O-(E)-feruloyl]glucoside, and tricin 7-O-beta-glucoside. The sum of all the flavone glycosides and soluble phenolic acids in the leaves decreased with increased rate of plant nutrients given in animal manure and with increased crop yield. All of the major phenylpropanoids showed the same general response to nutrient level. The concentration of nitrogen in the leaves was not directly related to nutrient application or to contents of phenylpropanoids.  相似文献   
9.
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号