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   27篇
  免费   4篇
林业   7篇
农学   6篇
  1篇
综合类   4篇
农作物   2篇
水产渔业   1篇
畜牧兽医   9篇
植物保护   1篇
  2023年   1篇
  2021年   1篇
  2020年   1篇
  2019年   1篇
  2017年   2篇
  2015年   3篇
  2013年   3篇
  2012年   1篇
  2011年   3篇
  2009年   1篇
  2008年   2篇
  2005年   2篇
  2004年   3篇
  2003年   2篇
  2001年   1篇
  1999年   1篇
  1996年   1篇
  1991年   1篇
  1990年   1篇
排序方式: 共有31条查询结果,搜索用时 0 毫秒
1.
We investigated whether the addition of either spinach or sweet-potato leaves to the diet of growing pigs, kept in small holdings in Central Vietnam, would improve growth performance. A control diet was formulated and mixed with each of the vegetables to a final concentration of 15% of the total dietary dry matter. The diets were fed to the pigs from 70 to 100 days of age on six different smallholder farms in Central Vietnam. There were three animals per treatment group per farm and biopsies of adipose tissue were analysed for their contents of alpha-linolenic, eicosapentaenoic and docosahexaenoic acids. The diets without and with vegetables contained on average 0.14 and 0.32 g alpha-linolenic acid per MJ metabolizable energy. The relative percentage of alpha-linolenic acid in adipose tissue was raised by the intake of the vegetables. Eicosapentaenoic acid was not detectable in adipose tissue and the level of docosahexaenoic acid was unchanged. There was a significant stimulatory impact of the intake of either spinach or sweet-potato leaves on growth performance of the growing pigs. It is suggested that an adipose tissue content of alpha-linolenic acid less than 1% of total fatty acids does not allow maximum growth in growing pigs.  相似文献   
2.
在乡村振兴与农业现代化发展大背景下,小农户经营面临前所未有的挑战。对福建省漳州地区小农户发展现状的观察发现,受主客观条件制约,小农户在现代农业发展中面临缺乏面向大市场的议价决策能力,现代科技运用滞后,与大资本间利益连接机制不稳定,农业社会化服务体系不健全等一系列困境。因此,要通过提高小农户组织化程度,拓宽市场渠道,提升小农户发展现代农业的能力,完善农业社会化服务体系,拓宽农业功能等助力小农户融入中国农业现代化进程。  相似文献   
3.
In this paper the author: (a) discusses the uniqueness of rattan among non-timber forest products, (b) examines the financial and the economic profitability of smallholder rattan cultivation, and (c) outlines a strategy for expanding smallholder rattan plantations among non-traditional producers.  相似文献   
4.
This paper examines the influence of important socio-economic, institutional/policy level factors in determining the adoption/non-adoption of rubber-integrated farming systems in traditional and non-traditional rubber-growing regions in India. The empirical analysis is based on a survey of rubber growers in the traditional rubber regions of Kerala (south India) and the non-traditional rubber regions of Assam, Meghalaya, and Tripura (north east India). In sharp contrast to Kerala, where smallholder responses toward adoption of rubber-integrated farming systems have been lukewarm, the emerging rubber economies (most of which are tribal communities) of north east (NE) India have shown interest in adopting rubber as an integrated farming system along with pre-existing land-use livelihood activities. The study clearly demonstrates contrasting empirical evidence of adoption of rubber-integrated farm-livelihood systems in the rubber-growing regions in Kerala and the NE states in India. The contrasting scenarios of adoption of rubber-integrated farming systems are mostly explained by region-specific factors dominated by socio-economic, institutional variables, and policy-level constraints, as also revealed by multivariate analysis. By and large, the findings of the study have significant bearing on the socio-economic outcomes and the existing institutional development paradigm underlying the rubber-development programmes introduced in India since independence. The study shows that the existing institutional arrangements and policies, which evolved historically to facilitate rubber area expansion in the traditional regions (including Kerala), have been highly instrumental in perpetuating rubber farming as a monoculture system. However, such an institutional mechanism proves to be highly redundant in the context of the NE states which are otherwise diverse in terms of integrated farm-livelihood systems and shifting cultivation.  相似文献   
5.
A retrospective cross-sectional study was conducted on 200 randomly selected smallholder farms from a mixed dairy farming system in Tanga, Tanzania, between January and April 1999. We estimated the frequency and determinants of long calving interval (LCI), retention of fetal membrane (RFM), dystocia, and abortion in smallholder crossbred cattle and explored birth trends. The mean calving interval was 500 days and birth rate was 65 per 100 cow-years. Dystocia was reported to affect 58% of calvings, and 17.2% of animals suffered RFM. Using mixed effect models, the variables associated with LCI, RFM and dystocia were breed, level of exotic blood and condition score. Zebu breeding was associated with LCI (odds ratio (OR) = 2.3, p = 0.041) and Friesian breeding with lower odds for RF (OR = 0.26, p = 0.020). Animals with higher levels of exotic blood had lower odds for evidence of dystocia (OR = 0.45, p =0.021). Evidence of dystocia was significantly associated with poor condition score (P = −1.10, p = 0.001). Our observations suggest that LCIs are common in smallholder dairy farms in this region and a likely source of economic loss. Dystocia, RFM, poor condition score and mineral deficiency were common problems and were possibly linked to LCI.  相似文献   
6.
Despite its small area and intensively cropped landscape, East Java accounts for 30% of Indonesia's cattle population. About two million households draw on family labour to raise cattle in backyard sheds and small enclosures, largely for cash income. In this paper, we examine the opportunity for such small‐scale producers to benefit from Indonesia's economic transformation, given the rising urban demand for beef. The paper reports on a study in two contrasting sites in East Java – irrigated lowlands and rainfed uplands – to explore the constraints facing small‐scale cattle producers in these environments, the means by which they have adapted to these constraints (especially by going beyond the farm household to access feed supplies) and possible means to enhance their production systems and incomes. The findings suggest that such cattle production systems can provide a viable source of livelihood, even for resource‐poor households; hence, appropriately adapted cattle improvement programmes are a sensible component of a pro‐poor development strategy.  相似文献   
7.
Based on the results of participatory approaches to define traits in the breeding objectives, four scenarios of ram selection and ram use were compared via deterministic modelling of breeding plans for community-based sheep breeding programmes in four diverse agro-ecological regions of Ethiopia. The regions (and production systems) were Afar (pastoral/agro-pastoral), Bonga and Horro (both mixed crop-livestock) and Menz (sheep-barley). The schemes or scenarios differed in terms of selection intensity and duration of ram use. The predicted genetic gains per year in yearling weight (kilograms) were comparable across the schemes but differed among the breeds and ranged from 0.399 to 0.440 in Afar, 0.813 to 0.894 in Bonga, 0.850 to 0.940 in Horro, and 0.616 to 0.699 in Menz. The genetic gains per year in number of lambs born per ewe bred ranged from 0.009 to 0.010 in both Bonga and Horro. The predicted genetic gain in the proportion of lambs weaned per ewe joined was nearly comparable in all breeds ranging from 0.008 to 0.011. The genetic gain per year in milk yield of Afar breed was in the order of 0.018 to 0.020 kg, while the genetic gain per generation for greasy fleece weight (kg) ranged from 0.016 to 0.024 in Menz. Generally, strong selection and shorter duration of ram use for breeding were the preferred options. The expected genetic gains are satisfactory but largely rely on accurate and continuous pedigree and performance recording.  相似文献   
8.
Globally, cocoa is famous for the production of chocolates and beverages. However, it also serves as a source of raw material for the manufacturing of high-quality cosmetic and pharmaceutical products. Due to its high demand, cocoa is regarded as a major commodity for poverty alleviation in deprived cocoa farming communities. Government has therefore instigated relevant measures to address issues facing the sector by investing in extension programs. These programs act as information dissemination tools for teaching modern farming technologies and enhancing learning among farmers. This study highlighted the effects of the Cocoa Life Project(CLP) by Cooperative for Assistance and Relief Everywhere(CARE) International on farm productivity and income of 200 cocoa farmers in three districts of the Eastern Region, Ghana. Regression on covariates, Heckman's treatment effects model, and propensity scores were used to test the robustness of the estimates. A positive association between extension program participation, farm productivity, and household income was discovered. Specifically, after correcting for selection bias, the estimated results of the Heckman's model showed that the extension program significantly increased participating farmers' cocoa yield by 14.3%. The effects on total farm income showed a significant increase of 25.1 and 42.9%, respectively from regression on propensity scores and the Heckman's model. Across all three models, program participation led to an increase in total household income by 46.1, 31.7, and 69.3%, respectively. Other variables such as farming characteristics, institutional and demographic factors affected farmers' income, depending on the estimation method used. This study reiterated the supporting role played by extension programs in enhancing cocoa production and increasing household income in Ghana. Conclusively, government and development partners should invest in extension programs by providing enough logistics, training qualified agents, and creating a conducive atmosphere to support learning and technology adoption.  相似文献   
9.
10.
基于云南西双版纳、海南植胶区的问卷调查数据,分析农户对自然灾害的认知情况和部分救灾措施,以及灾后的政府救济。研究发现:影响两大植胶区的主要自然灾害类型差别不大,风害、白粉病和小蠹虫主要发生在海南植胶区,而云南西双版纳则主要是风害、白粉病和干旱,且后者灾害类型分布相对前者更加均匀;农户应对病虫害的积极性明显高于干旱和寒害,海南植胶区农户更加重视台风的灾后处理而忽视灾前防范工作,云南西双版纳植胶区农户病虫害应对措施更为积极合理;政府部门对农户的自然灾害救济力度较弱,还未建立完善的救灾应急体系。  相似文献   
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