全文获取类型
收费全文 | 1029篇 |
免费 | 70篇 |
专业分类
林业 | 82篇 |
农学 | 21篇 |
基础科学 | 2篇 |
170篇 | |
综合类 | 86篇 |
农作物 | 36篇 |
水产渔业 | 44篇 |
畜牧兽医 | 518篇 |
园艺 | 14篇 |
植物保护 | 126篇 |
出版年
2023年 | 9篇 |
2022年 | 8篇 |
2021年 | 29篇 |
2020年 | 23篇 |
2019年 | 28篇 |
2018年 | 24篇 |
2017年 | 27篇 |
2016年 | 34篇 |
2015年 | 25篇 |
2014年 | 41篇 |
2013年 | 42篇 |
2012年 | 80篇 |
2011年 | 90篇 |
2010年 | 37篇 |
2009年 | 46篇 |
2008年 | 67篇 |
2007年 | 70篇 |
2006年 | 71篇 |
2005年 | 64篇 |
2004年 | 52篇 |
2003年 | 39篇 |
2002年 | 45篇 |
2001年 | 12篇 |
2000年 | 13篇 |
1999年 | 15篇 |
1998年 | 10篇 |
1997年 | 9篇 |
1996年 | 8篇 |
1995年 | 9篇 |
1994年 | 8篇 |
1993年 | 3篇 |
1992年 | 7篇 |
1991年 | 8篇 |
1990年 | 3篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1978年 | 3篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 4篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1958年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1099条查询结果,搜索用时 328 毫秒
51.
Ruscena WIEDERHOLT Anne M. TRAINOR Nicole MICHEL Patrick D. SHIREY Ronald R. SWAISGOOD Doug TALLAMY Susan C. COOK‐PATTON 《Integrative zoology》2015,10(5):436-452
In its 40‐year history, the science of conservation has faced unprecedented challenges in terms of environmental damage and rapid global change, and environmental problems are only increasing as greater demands are placed on limited natural resources. Conservation science has been adapting to keep pace with these changes. Here, we highlight contemporary and emerging trends and innovations in conservation science that we believe represent the most effective responses to biodiversity threats. We focus on specific areas where conservation science has had to adjust its approach to address emerging threats to biodiversity, including habitat destruction and degradation, climate change, declining populations and invasive species. We also document changes in attitudes, norms and practices among conservation scientists. A key component to success is engaging and maintaining public support for conservation, which can be facilitated through the use of technology. These recent trends in conservation and management are innovative and will assist in optimizing conservation strategies, increasing our leverage with the general public and tackling our current environmental challenges. 相似文献
52.
Nicole A. Boynosky Laura Stokking 《The Canadian veterinary journal. La revue veterinaire canadienne》2014,55(5):484-488
A 2-year-old neutered male golden retriever dog presented for lameness secondary to ulcerations of multiple digital paw pads was diagnosed with vasculitis and hypercholesterolemia. Despite treatment, ischemic necrosis progressed to include all distal extremities and the dog eventually expired due to myocardial infarction secondary to severe atherosclerosis. The rapid demise and the dermatologic lesions may have been secondary to cholesterol embolism syndrome which has never before been reported in a dog. 相似文献
53.
54.
55.
56.
57.
58.
59.
The yellow-legged hornet (Vespa velutina) is the first invasive Vespidae predator of honeybees to be accidentally introduced into Europe from Asia. In the current pollinator decline, V. velutina is an additional stressor for honeybees and other pollinators. Although V. velutina contributes to the loss of honeybee colonies, little is known about its biology and behaviour both in the native and in the invaded area. Here, we review the current knowledge of this species and describe its life cycle and life history traits (reproduction, overwintering, foraging and dispersal) in the light of the biology of other Vespidae. We also review the impact of this species on ecosystems, on the economics of beekeeping, and on human health (this species being potentially deadly for allergic people). Based on this information and on previous worldwide experiences with Vespidae invasions, we propose key research topics for the development of effective management plans. We identify methods to limit the impact and proliferation of V. velutina in Europe that are based on nest destruction, trapping, population genetics, and biological control. In our opinion, research effort on the means to detect and destroy V. velutina nests at an early stage is required in order to short-circuit the colony cycle and thus limit both its impact on honeybees and its expansion through Europe. Finally, we discuss the impact of this biological invasion on the development of methods that should be used to manage alien species in the future. 相似文献
60.
Helga Guderley Brigitte A. Lavoie Nicole Dubois 《Fish physiology and biochemistry》1994,13(5):419-431
Thermal acclimation may directly modify muscle metabolic capacities, or may modify them indirectly via effects upon physiological processes such as growth, reproduction or senescence. To evaluate these interacting effects, we
examined the influence of thermal acclimation and acclimatization upon muscle metabolic capacities and tissue masses in 1
+ stickleback, Gasterosteus aculeatus, in which confounding interactions between temperature and senescense should be absent. Furthermore, we examined the influence
of thermal acclimation upon individual growth rate, muscle enzyme levels and tissue masses in 2 + stickleback sampled at the
beginning of their final reproductive season. For 1 + stickleback, cold acclimation more than doubles mitochondrial enzyme
levels in the axial muscle. Thermal acclimation did not change the condition of 1 + stickleback at feeding levels which could
not maintain the condition of 2+ stickleback. Compensatory metabolic responses to temperature were not apparent in field acclimatized
1 + stickleback. The growth rate of 2 + stickleback was markedly affected by temperature: warm-acclimated fish generally lost
mass even at very high levels of feeding (up to 78 enchytraid worms per day) while cold-acclimated fish gained mass. This
suggests that warm temperatures accelerate the senescence of 2 + stickleback. Generally, muscle enzyme activities increased
with growth rate. In axial muscle, the relationships between CS activity and growth rate differed with acclimation temperature.
Independent of the influence of growth rate, CS activities were consistently higher in cold- than warm-acclimated 2 + stickleback,
suggesting compensatory increases of CS activity with cold acclimation.
Corresponding author; This paper is dedicated to the memory of Gerry J. FitzGerald who passed away on March 14, 1994. 相似文献