全文获取类型
收费全文 | 109篇 |
免费 | 4篇 |
专业分类
林业 | 7篇 |
农学 | 5篇 |
基础科学 | 3篇 |
9篇 | |
综合类 | 15篇 |
农作物 | 5篇 |
水产渔业 | 8篇 |
畜牧兽医 | 34篇 |
园艺 | 4篇 |
植物保护 | 23篇 |
出版年
2022年 | 5篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 7篇 |
2015年 | 2篇 |
2013年 | 4篇 |
2012年 | 2篇 |
2011年 | 8篇 |
2010年 | 3篇 |
2009年 | 6篇 |
2008年 | 11篇 |
2007年 | 4篇 |
2006年 | 2篇 |
2005年 | 6篇 |
2004年 | 3篇 |
2003年 | 12篇 |
2002年 | 3篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1993年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1984年 | 2篇 |
1983年 | 2篇 |
排序方式: 共有113条查询结果,搜索用时 125 毫秒
21.
Introduction of the clonedErwinia chrysanthemi pelB orpelE genes intoEscherichia coli enabled the latter to cause blackleg disease symptoms in potato similar to those observed with the pathogenErwinia carotovora. TheE. coli cells multiplied in the roots and moved systemically in the potato stems, concomitant with the appearance of disease symptoms.E. coli cells expressing the clonedpel genes also interacted with the fungal pathogen,Verticillium dahliae, as observed previously withErwinia spp. The results indicate that either of two clonedpel genes permitsE. coli to cause relatively sophisticated diseases in potato plantlets. 相似文献
22.
近年来,肠道菌群研究获得的重大突破表明,卵形拟杆菌具有代谢多糖及胆碱盐的能力,对于治疗糖尿 病、心血管疾病、炎症性肠病及癌症等具有生理功效,被认为是具有潜在益生作用的下一代益生菌,具有极其广阔 的研究和应用前景,已成为近年来国内外研究的热点。然而,目前对于卵形拟杆菌的细菌学特性、功能特性和应用 前景还没有较为系统全面的总结。本文主要从卵形拟杆菌的细菌学特性、功能特性和应用前景三方面综述卵形拟杆 菌的研究现状,以期为国内外同行进行相关研究和应用提供参考。 相似文献
23.
24.
采用热平衡包裹式树干茎流测量系统(Stem Heat Balance,SHB)和自动气象站观测沙木蓼生长季茎干液流以及环境因子,以揭示毛乌素沙地沙木蓼(Atraphaxis bracteata A.Los)蒸腾耗水规律。结果表明:1)沙木蓼液流具有明显的昼夜节律,启动、停止与日出、日落同步,夜间仍保持一定液流,以补充植物体水分亏缺。2)沙木蓼液流规律受天气影响显著:降雨时白天的液流速率大幅下降,夜间液流却大幅提升,日液流总量降至晴天的一半;阴天液流速率平缓,昼夜差距减小,液流总量较晴天小幅下降;多云天液流速率波动剧烈,但总液流量变化不大。3)沙木蓼生长季的液流量与土壤水分状况和植物体的生长阶段密切相关,6、7月份沙木蓼植株处在旺盛的营养生长阶段,新叶生长迅速,加上土壤含水充足,液流量总体是增长趋势,从7月末到8月份沙木蓼植株从营养生长期过渡到生殖生长以开花结果为主的阶段,蒸腾减小,同时天气干旱土壤水分逐渐亏缺,液流量呈下降趋势。4)从6月到8月基茎9mm,16mm,25mm的沙木蓼总耗水分别为100.8kg,170.5kg,301.3kg。沙木蓼植株生长季茎干液流总量基本与基茎成正比,平均为11.5kg/mm/a,可以用来作各个茎级沙木蓼植株的茎干液流推算,进而推算已知林分的总蒸腾耗水量。 相似文献
25.
Meidan R Levy N Kisliouk T Podlovny L Rusiansky M Klipper E 《Domestic animal endocrinology》2005,29(2):318-328
A dense network of capillaries irrigates the corpus luteum (CL) allowing an intricate cross talk between luteal steroiodgenic and endothelial cell (EC) types. Indeed, luteal endothelial cells (LEC) play pivotal roles throughout the entire CL life-span. Microvascular endothelial cells are locally specialized to accommodate the needs of individual tissues, therefore unraveling the characteristics of LEC is imperative in CL physiology. Numerous studies demonstrated that endothelium-derived endothelin-1 (ET-1) is upregulated by the luteolytic hormone-prostaglandin F2alpha (PGF2alpha) and functions as an important element of the luteolytic cascade. To have a better insight on its synthesis and action, members of ET system (ET-1, ET converting enzyme -ECE-1 and ET(A) and ET(B) receptors) were quantified in LEC. The characteristic phenotype of these cells, identified by high ET-1 receptor expression (both ET(A), ET(B)) and low ET-1 and ECE-1 levels, was gradually lost during culture suggesting that luteal microenvironment sustains the selective phenotype of its resident endothelial cells. Proper vascularization and endothelial cell activity per se are essential for normal CL function. Therefore, factors affecting vascular growth are expected to play major role in the regulation of luteal function. Concomitantly with the angiogenic process, luteal PGF2alpha and its receptors (PGFR) are induced and maintained during most of the CL life-span, suggesting a possible role of PGF2alpha in LEC proliferation and function. Dispersed LEC expressed PGFR and incubation with the prostaglandin stimulated mitogen-activated protein kinase (MAPK) signaling cascade. PGF2alpha activated p42/44 MAPK phosphorylation also in long-term cultured LEC. In this cell type, PGF2alpha increased cell number, 3H-Thymidine incorporation and cell survival. Additionally, PGF2alpha rapidly and transiently stimulated the expression of immediate-early response genes, i.e. c-fos and c-jun mRNA, further suggesting a mitogenic effect for this prostaglandin in LEC. These data imply that PGF2alpha may assume different and perhaps opposing roles depending on luteal microenvironment. 相似文献
26.
27.
黄斑星天牛硫酰氟检疫熏蒸技术研究 总被引:3,自引:1,他引:3
黄斑星天牛 (Anoplophoranobilis)硫酰氟熏蒸的毒力试验结果说明 ,当熏蒸时间为2 4h ,4.4℃、1 0 .0℃、1 5.5℃和 2 1 .1℃条件下推算出死亡机率值 9要求的CT值分别为70 0 4.2 0、3 2 96.97、974.63和 52 7.0 4g .h/m3;当熏蒸时间为 48h ,4.4℃和 2 1 .1℃分别为 2 82 8.2 2和 50 5.45g .h/m3。室内验证试验中 ,1 5.5℃和 2 1 .1℃投药剂量为 1 0 4g/m3,能够全部杀灭杨树携带的黄斑星天牛幼虫、蛹 ,以及芳香木蠹蛾东方亚种 (Cossuscossusorientalis)和杨干透翅蛾 (Spheciasiningensis)幼虫 ;而在 1 0℃以下 ,黄斑星天牛或芳香木蠹蛾东方亚种和杨干透翅蛾幼虫没有完全死亡。 相似文献
28.
木质包装集装箱溴甲烷检疫熏蒸技术研究 总被引:5,自引:1,他引:5
对集装箱装运的出口货物木质包装进行了溴甲烷熏蒸试验 ,结果说明 ,当环境温度为 2~ 1 6℃时 ,采用溴甲烷投药剂量 80 g/m3 ,熏蒸 2 4h能够全部杀死黄斑星天牛幼虫 ,其CT值为 1 1 2 5 8~ 3345 3g h/m3 ;环境温度为 5~ 2 0℃时 ,采用 6 4g/m3 投药剂量 ,同样熏蒸 2 4h ,CT值为 1 2 1 0 8~ 1 51 0 8g h/m3 ,黄斑星天牛幼虫同样全部死亡。溴甲烷汽化后直接从集装箱门上部投药能够使药剂分布均匀。熏蒸结束后通风散气 2 4h ,集装箱到达美国后其内部溴甲烷残留气体浓度低于 5× 1 0 -6。 相似文献
29.
Three systems of carp (Cyprinus carpio) culture (live food system, manured system, and control system) were used to examine environmentally dependent life history characteristics of zooplankton, Moina micrura. Twelve culture tubes with one neonate of M. micrura per tube and covered by nylon bolting cloth of 75 μm mesh size were suspended in situ in each culture system. Each culture tube was examined daily to evaluate life history patterns. Time to first reproduction ranged from 4 to 7 days in the control and manured systems and 3 to 5 days in the live food system. Mean longevity, net reproductive rate, average generation time, as well as total offspring production per female, were distinctly higher for the live food system than for the manured or control systems. Interactions between chemical oxygen demand, dissolved oxygen, phosphate levels and primary productivity resulting in optimal conditions were responsible for large variations in life history characteristics of M. micrura among the culture systems. 相似文献
30.