全文获取类型
收费全文 | 724篇 |
免费 | 39篇 |
专业分类
林业 | 43篇 |
农学 | 16篇 |
基础科学 | 3篇 |
103篇 | |
综合类 | 56篇 |
农作物 | 25篇 |
水产渔业 | 25篇 |
畜牧兽医 | 409篇 |
园艺 | 16篇 |
植物保护 | 67篇 |
出版年
2023年 | 7篇 |
2022年 | 4篇 |
2021年 | 9篇 |
2020年 | 19篇 |
2019年 | 16篇 |
2018年 | 12篇 |
2017年 | 15篇 |
2016年 | 21篇 |
2015年 | 23篇 |
2014年 | 25篇 |
2013年 | 48篇 |
2012年 | 52篇 |
2011年 | 62篇 |
2010年 | 32篇 |
2009年 | 49篇 |
2008年 | 47篇 |
2007年 | 42篇 |
2006年 | 33篇 |
2005年 | 38篇 |
2004年 | 42篇 |
2003年 | 27篇 |
2002年 | 27篇 |
2001年 | 10篇 |
2000年 | 16篇 |
1999年 | 10篇 |
1998年 | 5篇 |
1997年 | 8篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1973年 | 5篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1969年 | 2篇 |
1968年 | 1篇 |
1954年 | 1篇 |
1948年 | 1篇 |
排序方式: 共有763条查询结果,搜索用时 15 毫秒
21.
Measuring the productivity and physical workload of brushcutters within the context of a production-based pay system 总被引:1,自引:0,他引:1
Dominic Toupin Luc LeBel Denise Dubeau Daniel Imbeau Luc Bouthillier 《Forest Policy and Economics》2007,9(8):1046-1055
Forestry occupations are known to be physically demanding, and workers are often paid on a piece rate basis. This pay system is largely used in silvicultural treatments such as plantation and vegetation management. An ill adjusted piece rate system may induce workforce recruitment difficulties or increase accident rates and work related illnesses. A study combining work measurement, ergonomics and economics was undertaken to better understand the factors influencing a worker's workload. Mathematical relations between site factors, worker's production and heart rate variation during work have been examined based on time and motion studies of 38 brushsaw operators performing regeneration release (cleaning) in northern forests. Results show that a piece rate pay system that considers only the area treated without taking into account site factors may lead workers to behave in ways that may compromise their health and safety. The use of a pay system that integrates the influence of site factors on work performance is therefore suggested. 相似文献
22.
Florence Clostre Thierry Woignier Luc Rangon Paula Fernandes Alain Soler Magalie Lesueur-Jannoyer 《Journal of Soils and Sediments》2014,14(1):23-33
Purpose
The use of chlordecone (CLD) has caused pollution of soils, which are now a source of contamination for crops and ecosystems. Because of its long-term impacts on human health, exposure to CLD is a public health concern and contamination of crops by CLD must be limited. To this end, we conducted field trials on chlordecone sequestration in soil with added compost.Materials and methods
The impact of added compost on chlordecone sequestration was measured in nitisols. After characterization of the soil, the transfer of chlordecone from soil to water was assessed in a leaching experiment and from soil to two crop plants in a nitisol plot. Finally, to understand the underlying processes, changes in CLD content were measured in soil fractions and soil porous properties were assessed after the addition of compost.Results and discussion
A rapid seven-fold decrease in water extractable CLD was observed in amended soils. Five percent amendment led to a significant reduction in the contamination of crops by CLD; edible radish tubers were 50% more contaminated without added compost and cucumber fruits were 60% more contaminated. After the addition of compost, CLD content increased in the fraction of pre-humified or partially mineralized organic debris. Finally, in contrast to andosols, adding compost to nitisols did not affect the soil microstructure.Conclusions
Increasing chlordecone sequestration by adding compost could be an alternative solution until soil decontamination techniques become available. This could be a provisional way to control further release of CLD from contaminated soils towards other environmental compartments. 相似文献23.
Sutherland MA Mellor DJ Stafford KJ Gregory NG Bruce RA Ward RN Todd SE 《Australian veterinary journal》1999,77(11):738-741
OBJECTIVE: To test whether injecting lignocaine into the scrotal neck 5 to 10 s before or into both testes immediately after ring castration and docking wound significantly reduce the plasma cortisol response to castration and docking. DESIGN: A physiological study with controls. PROCEDURE: Lambs were given one of six treatments: control handling, injection of lignocaine into scrotal neck, injection of lignocaine into both testes, ring castration and docking, ring castration and docking after lignocaine was injected into the scrotal neck, and ring castration and docking before lignocaine was injected into both testes. Blood samples were taken before and regularly after treatment and analysed for plasma cortisol concentrations. RESULTS: The plasma cortisol concentrations of lambs castrated and docked after lignocaine had been injected into the scrotal neck were significantly lower between 20 and 60 min after treatment than in lambs castrated and docked without local anaesthesia. Injecting lignocaine into the testes after ring application did not significantly reduce the cortisol response to ring castration and docking. CONCLUSIONS: Lignocaine injected into the scrotal neck 5 to 10 s before ring castration will reduce the cortisol response and by inference the pain associated with ring castration. 相似文献
24.
Todd SE Mellor DJ Stafford KJ Gregory NG Bruce RA Ward RN 《Research in veterinary science》2000,68(2):125-134
The effects of food withdrawal for 30 hours and transport for up to 12 hours on 5- to 10-day-old calves were determined by monitoring plasma concentrations of glucose, beta-hydroxybutyrate, urea, lactate and creatine phosphokinase. In addition gamma-glutamyl transferase activity, packed cell volume, total plasma protein concentration, bodyweight and rectal temperature were recorded. Food withdrawal for 30 hours caused hypoglycemia but calves maintained normothermia and although their beta-hydroxybutyrate level increased indicating lipid mobilisation, the changes in blood urea level were minimal indicating low amino acid catabolism. When calves were transported for 12 hours in addition to having food withdrawn for 30 hours, they remained normoglycemic for six hours longer than non-transported calves, probably due to an effect of muscular activity during bracing against truck movements. Stocking calves at a lower density during transport apparently had a beneficial effect, as calves were able to lie down throughout the journey and therefore produced a similar metabolic profile to resting, non-transported animals. Transport and food withdrawal had no obvious effects on calf hydration. The results of this study suggest that food withdrawal for up to 30 hours and transport for up to 12 hours had no detrimental effects on the metabolism of healthy and clinically normal calves. With correct feeding regimes and transport protocols, welfare compromise in young, healthy calves being transported for up to 12 hours can be minimised when they are slaughtered within 30 hours of the start of transport. 相似文献
25.
26.
Moerkens Rob Berckmoes Els Van Damme Veerle Wittemans Lieve Tirry Luc Casteels Hans De Clercq Patrick De Vis Raf 《植物病害和植物保护杂志》2017,124(3):295-303
Journal of Plant Diseases and Protection - Macrolophus pygmaeus Rambur (Hemiptera: Miridae) is a key biological control agent in greenhouse tomato crops. In the present study, we describe the... 相似文献
27.
28.
Defauw PA Van de Maele I Duchateau L Polis IE Saunders JH Daminet S 《Journal of Feline Medicine and Surgery》2011,13(12):967-975
Feline idiopathic cystitis (FIC) is the most common cause of feline lower urinary tract disease (FLUTD). This retrospective, case-controlled study evaluated possible risk factors associated with FIC and compared different clinical presentations in 64 cats with FIC. Several risk factors known to be involved in FLUTD were identified as playing a role in FIC. Of the stressful situations considered, most did not occur with increased frequency in cats with FIC compared to controls, except for a house move. The presence of pyuria, haematuria and an increased urine protein:creatinine ratio were significantly higher in obstructed males compared with non-obstructed males. An obstruction was significantly more likely in cats with struvite crystalluria compared with cats without struvite crystalluria. These findings suggest that urethral plugs might be an important cause or contributing factor of obstruction in FIC. Episodes of FIC seem to occur mainly in susceptible cats in combination with a deficient environment. 相似文献
29.
30.