全文获取类型
收费全文 | 382篇 |
免费 | 32篇 |
国内免费 | 13篇 |
专业分类
林业 | 114篇 |
农学 | 8篇 |
基础科学 | 9篇 |
21篇 | |
综合类 | 107篇 |
农作物 | 26篇 |
水产渔业 | 2篇 |
畜牧兽医 | 16篇 |
园艺 | 11篇 |
植物保护 | 113篇 |
出版年
2024年 | 1篇 |
2023年 | 9篇 |
2022年 | 6篇 |
2021年 | 15篇 |
2020年 | 8篇 |
2019年 | 9篇 |
2018年 | 9篇 |
2017年 | 10篇 |
2016年 | 14篇 |
2015年 | 9篇 |
2014年 | 15篇 |
2013年 | 17篇 |
2012年 | 18篇 |
2011年 | 29篇 |
2010年 | 22篇 |
2009年 | 31篇 |
2008年 | 36篇 |
2007年 | 20篇 |
2006年 | 18篇 |
2005年 | 15篇 |
2004年 | 20篇 |
2003年 | 10篇 |
2002年 | 6篇 |
2001年 | 14篇 |
2000年 | 7篇 |
1999年 | 10篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 8篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 9篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有427条查询结果,搜索用时 156 毫秒
21.
Rinat Ismagilovich Ibragimov ;Ildar Salimyanovich Mardanshin ;Galina Vasilyevna Benkovskaya ;Maksim Borisovich Udalov ;Irina Andreevna Shpirnaya ;Vyacheslav Olegovich Tsvetkov 《农业科学与技术》2014,(4):331-341
In field and laboratory conditions the reproductive potential (survival at different stages of development) of the Colorado potato beetle has been measured, the dependence of the parameters of insects fertility on varietal features of the feed has been investigated, the food activity of the representatives of insects from four areas of the Southern Urals has been measured, the intensity and time of hypersensitivity reactions on potato leaves has been defined. In laboratory experiments, the level of activity of hydrolytic enzymes in insects and the level of activity of these enzymes inhibitors in the leaves of three potato varieties differing in their resistance to the Colorado potato beetle have been determined. The results show that the insects-representatives of different samples have different food activity in relation to different potato varieties. High mortality rates were revealed at feeding with leaves of potato of the Bashkir variety characterized by a high level of hydrolases inhibitors and relatively rapid development of necrotic reactions after the appearance of eggs laying on the leaves. We suppose that the neerogenetic barrier appearing in the form of necrosis is the major cause of the fetal mortality of insects. The level of the content of inhibitors inactivating larvae digestive enzymes affects the survival of insects at postembryonic stages. The speed of the necrosis emergence, the level of activity of digestive enzymes inhibitors in potato can be considered as criteria for the selection of breeding material for resistance to the Colorado potato beetle. 相似文献
22.
从臭蜣螂中提取甲壳素/壳聚糖的研究 总被引:9,自引:0,他引:9
甲壳素作为自然界中产量仅次于纤维素的第二大生物资源 ,近年来其开发和应用日益受到重视 ,但目前甲壳素的生产原料来源有限 ,生产成本较高。而昆虫是世界上最大的优势动物种类 ,昆虫的总生物量超过了地球上所有动物总生物量 ;但被人类利用的昆虫资源却很少。昆虫是当今地球上未被利用的最大生物资源 ,特别是昆虫的甲壳素资源尚未开发。鉴于目前对于昆虫甲壳素资源的开发尚在尝试阶段 ,本文以臭蜣螂为材料 ,进行了提取甲壳素和壳聚糖的工艺以及其理化特性研究。研究发现 ,臭蜣螂体中甲壳素含量高出目前甲壳素生产常规原料虾蟹壳数倍 ,且从其体中提取的甲壳素与壳聚糖的品质在残留灰分、粘度和色泽等方面优于虾蟹壳。并以单因素试验方法进行了提取甲壳素和壳聚糖提取工艺的研究 ,提出了从臭蜣螂中提取甲壳素和壳聚糖的提取工艺 :①脱矿物质 :用 0 8mol·L- 1 HCl预先 70℃加热 30min ,然后室温条件下浸泡 12h ;②脱蛋白质、脂类 :用 2 0~ 2 5mol·L- 1 NaOH ,在 90~ 10 0℃条件下 ,处理 4~ 5h ;③脱乙酰基 :用 10 0 0~ 11 2 5mol·L- 1 NaOH ,在 130℃条件下 ,处理 3h。 相似文献
23.
花椒红胫潜跳甲(Podagricomela flavitibialis Wang)、花椒铜色潜跳甲(Podagricomela cuprea Wang)、花椒桔啮跳甲(Clites seiahatai Chuyo)三种跳甲都以成虫在花椒树冠下周围表土层7cm以内越冬。在花椒展叶后越冬成虫开始出土活动,4月下旬至5月中旬为产卵盛期孵化盛期,这一时期是药剂防治最关键时期。试验结果表明,花椒休眠期树冠下覆膜防治花椒三种跳甲效果显著,同时花椒树覆膜后抗旱保水、提高地温,也有明显的增产效果,且对环保无污染,安全可靠,操作简便,符合无公害农产品生产的技术要求。 相似文献
24.
应用扩展的均匀设计 ,探讨菜田不同黄曲条跳甲幼虫基数、斯氏线虫 (A2 4 品系 )施用量和不同施用条带等条件下线虫对黄曲条跳甲种群控制效果 .结果表明 ,黄曲条跳甲幼虫基数的大小和线虫施用条带是影响控制效果的主要因素 .而在这几个因素中 ,在线虫一定施用量范围内 ,线虫数量的作用并不是主要因素 .同时建立了控制效果随这些因素变化的动态模型 .通过对模型的分析和模拟 ,建立了田间不同条件下线虫的定量化应用技术 . 相似文献
25.
云杉小黑天牛生物学特性的研究 总被引:1,自引:0,他引:1
1987年5月6日,大兴安岭林区发生特大森林火灾以后,火烧迹地,贮木场云杉小黑天牛大量发生。在塔河林业局绣峰林业公司贮木场抽样调查中,原木被害率为54.07%,降等率为42.23%,每立方米损失约34.29元。云杉小黑天牛在该地区一年发生一代。以幼虫在木质部内越冬。5月下旬化蛹,高峰期为6月上旬;6月上旬成虫羽化,高峰期为6月下旬;产卵高峰期为7月初;孵化高峰期为7月上旬。卵期平均9d,蛹期平均19d,成虫期15—30d,幼虫期长达250—300d。 相似文献
26.
诊断剂量法在黄曲条跳甲抗性监测中的应用 总被引:2,自引:1,他引:2
利用诊断剂量法测定的毒死蜱、丁硫克百威、氯氰菊酯3种杀虫剂的敏感个体与抗性个体诊断剂量分别为40和600mg.L-1、50和800 mg.L-1、63和1000 mg.L-1.根据诊断剂量,利用滤纸药膜法测定4个菜区黄曲条跳甲成虫的抗性个体频率,并与点滴法、浸叶法测定结果进行比较分析.结果表明利用诊断剂量法确定的平坡诊断剂量监测田间种群的药剂敏感性,基本上能够反映黄曲条跳甲田间种群的抗药性水平.因此,诊断剂量法也是一种可供选用的害虫抗性监测方法. 相似文献
27.
28.
BACKGROUND: RNA interference (RNAi) is a breakthrough technology for conducting functional genomics studies and also as a potential tool for crop protection against insect pests. The major challenge for efficient pest control using RNAi in the field is the development of efficient and reliable methods for production and delivery of double‐stranded RNA (dsRNA). In this paper, the potential of feeding dsRNA expressed in bacteria or synthesized in vitro to manage populations of Colorado potato beetle, Leptinotarsa decemlineata (Say) (CPB), was investigated. RESULTS: Feeding RNAi successfully triggered the silencing of all five target genes tested and caused significant mortality and reduced body weight gain in the treated beetles. This study provides the first example of an effective RNAi response in insects after feeding dsRNA produced in bacteria. CONCLUSION: These results suggest that the efficient induction of RNAi using bacteria to deliver dsRNA is a possible method for management of CPB. This could be also a promising bioassay approach for genome‐wide screens to identify effective target genes for use as novel RNAi‐based insecticides. Copyright © 2010 Society of Chemical Industry 相似文献
29.
Rosa M. Chefaoui 《Biological conservation》2005,122(2):327-338
Dung beetle populations, in decline, play a critical ecological role in extensive pasture ecosystems by recycling organic matter; thus the importance of their conservation status. Presence data available for Copris hispanus (L.) and Copris lunaris (L.) (Coleoptera, Scarabaeidae) in Comunidad de Madrid (CM), and BIOMAPPER, a GIS-based tool, was used to model their environmental niches. The so derived potential distributions of both species were used to exemplify the utility of this kind of methodologies in conservation assessment, as well as its capacity to describe the potential sympatry between two or more species. Both species, distributed along a Dry-Mediterranean to Wet-Alpine environmental conditions gradient, overlap in areas of moderate temperatures and mean annual precipitations in the north of CM. Copris are poorly conserved in the existing protected sites network, but protection provided by new sites included in the future Natura 2000 Network will improve the general conservation status of these species in CM. 相似文献
30.