全文获取类型
收费全文 | 2081篇 |
免费 | 51篇 |
国内免费 | 71篇 |
专业分类
林业 | 1篇 |
农学 | 211篇 |
基础科学 | 35篇 |
154篇 | |
综合类 | 863篇 |
农作物 | 53篇 |
水产渔业 | 2篇 |
畜牧兽医 | 3篇 |
园艺 | 736篇 |
植物保护 | 145篇 |
出版年
2024年 | 2篇 |
2023年 | 13篇 |
2022年 | 18篇 |
2021年 | 32篇 |
2020年 | 57篇 |
2019年 | 46篇 |
2018年 | 46篇 |
2017年 | 71篇 |
2016年 | 97篇 |
2015年 | 85篇 |
2014年 | 109篇 |
2013年 | 112篇 |
2012年 | 121篇 |
2011年 | 162篇 |
2010年 | 145篇 |
2009年 | 126篇 |
2008年 | 151篇 |
2007年 | 169篇 |
2006年 | 132篇 |
2005年 | 128篇 |
2004年 | 64篇 |
2003年 | 65篇 |
2002年 | 44篇 |
2001年 | 28篇 |
2000年 | 21篇 |
1999年 | 33篇 |
1998年 | 20篇 |
1997年 | 28篇 |
1996年 | 15篇 |
1995年 | 7篇 |
1994年 | 16篇 |
1993年 | 4篇 |
1992年 | 7篇 |
1991年 | 9篇 |
1990年 | 8篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1981年 | 3篇 |
排序方式: 共有2203条查询结果,搜索用时 15 毫秒
61.
[目的]筛选诱导珙桐茎愈伤组织的最佳培养基,为建立悬浮细胞系以及大规模繁殖珙桐提供前期技术基础。[方法]采集5年生以下珙桐的嫩枝条幼嫩茎为外植体,环割后接种在改良MS培养基上,培养基设25个处理,分别添加浓度为0、0.1、0.2、0.3、0.4 mg/L的NAA,浓度为0、10、20、30、40 mg/L的豆芽汁和浓度为0、5、10、15、20 mg/L的番茄汁。[结果]天然提取物和植物生长调节剂对珙桐茎诱导愈伤组织都有影响,其影响程度是NAA>豆芽汁>番茄汁。改良MS培养基添加30 mg/L豆芽汁+20 mg/L番茄汁+0.4 mg/LNAA是诱导珙桐茎愈伤组织的最佳培养基,诱导出的愈伤组织质量好,出愈率高达98%。[结论]添加天然提取物可诱导出质量好的珙桐茎愈伤组织,这与豆芽汁和番茄汁含有丰富的维生素B和维生素C有关。 相似文献
62.
63.
以温敏型核雄性不育系番茄T4及对照First为试材,通过调查花粉发芽率、自交结实率、果实种子数以及采用Tricine-SDS-PAGE电泳方法分析叶片及花药蛋白质的变化,研究T4的育性转化,并分析其在可育和不育条件下花粉发芽率、自交结实率、果实种子数、叶片及花药蛋白质的差异。结果表明:28 ℃/18 ℃(昼/夜)处理的T4花粉发芽率、自交结实率最高,果实种子数最多,与对照First差异不显著,表明此时T4恢复部分育性|28 ℃/24 ℃和28 ℃/12 ℃处理的T4花粉发芽率、自交结实率和果实种子数与对照差异均达到极显著水平,表现为不育。不同温度处理的T4花药蛋白质与叶片蛋白质差异均达到显著水平|28 ℃/24 ℃和28 ℃/12 ℃处理的T4叶片蛋白质与对照差异显著,但28 ℃/18 ℃处理的差异不明显。 相似文献
64.
65.
66.
67.
金冠六号是以06-441为母本,06-504为父本育成的早熟番茄新品种.无限生长型,生育期110天左右,平均单果质量200 g左右,可溶性固形物含量4.5%左右.果实扁圆形,粉红色,酸甜适口,果实硬度高,耐贮运,商品性好.抗病毒病和叶霉病,耐低温弱光能力强,适于保护地栽培. 相似文献
68.
Martina Caramante Rosa Rao Luigi Maria Monti Giandomenico Corrado 《Scientia Horticulturae》2009,120(4):560-564
‘San Marzano’ (SM) is one of the most widely known tomato (Solanum lycopersicum L.) cultivars, and is a classic example of a local variety with a premium value. Unfortunately, the original cultivated form is underrepresented in the Protected Denomination of Origin (PDO) area because of the incidence of contaminant and phenotypically similar genotypes. Our aim was to examine the ability of three DNA marker systems (minisatellite, cleaved amplified polymorphic sequence (CAPS) and simple sequence repeat (SSR)) to reveal the genetic diversity of tomato accessions that were, based on a morphological analysis, very similar. The data indicate that both minisatellites and SSRs can be used to genetically distinguish the analysed materials. Furthermore, these two marker systems depict relationships consistent with the hierarchal pattern obtained by the morphological data. As locally cultivated tomato accessions are often characterised by some degree of genetic variability, our results will be valuable in facilitating the purification, management and breeding of tomato germplasms. The differences between the marker systems employed are also discussed in relation to their usefulness in the agro-food chain. 相似文献
69.
70.
Fabrício Alves Oliveira Derly José Henriques da Silva Germano Leão Demolin Leite Gulab Newandram Jham Marcelo Picanço 《Scientia Horticulturae》2009
The aim of this study was to evaluate resistance to Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) by antixenosis on 57 Lycopersicon esculentum Mill. accessions from the Horticultural Germplasm Bank (HGB) of Universidade Federal de Viçosa and by the three commercial cultivars (Santa Clara, Moneymaker and TOM-601) under greenhouse conditions. A randomized complete block design was used with three replications. Infestations with T. absoluta adults were performed weekly and the following characteristics were evaluated: number of small, large and total mines/leaf and % of leaves mined at days 60, 75 and 90 after planting. Low infestation occurred at days 60 and 75 but at day 90, infestation was sufficient to evaluate insect damage. Based on these data it was concluded that only accessions HGB-674 and HGB-1497 appeared to be the most promising. In addition, to determine possible chemical causes of resistance, hexane extracts were analyzed at day 90 by gas chromatography/mass spectrometry and the major peaks identified by a mass spectral database using similarity index. Nine hydrocarbons, viz., hexadecane, heptadecane, eicosane, tricosane, 2-methyltricosane, tetracosane, hexacosane, octacosane and triacontane were identified in the hexane extracts in many samples. Tricosane, tetracosane and hexacosane presented significant correlations with the leaves mined. Only tricosane presented a negative correlation with the number of small mines (r = −0.28), total number of mines (r = −0.27) and % of leaves mined (r = −0.22). However, tetracosane and hexacosane presented significant positive correlations (r = 0.25 and 0.24, respectively) with the % of leaves mined. 相似文献