全文获取类型
收费全文 | 733篇 |
免费 | 60篇 |
专业分类
林业 | 33篇 |
农学 | 13篇 |
基础科学 | 3篇 |
76篇 | |
综合类 | 55篇 |
农作物 | 16篇 |
水产渔业 | 43篇 |
畜牧兽医 | 507篇 |
园艺 | 10篇 |
植物保护 | 37篇 |
出版年
2024年 | 4篇 |
2023年 | 19篇 |
2022年 | 13篇 |
2021年 | 27篇 |
2020年 | 16篇 |
2019年 | 30篇 |
2018年 | 25篇 |
2017年 | 30篇 |
2016年 | 19篇 |
2015年 | 21篇 |
2014年 | 28篇 |
2013年 | 24篇 |
2012年 | 46篇 |
2011年 | 55篇 |
2010年 | 23篇 |
2009年 | 23篇 |
2008年 | 29篇 |
2007年 | 27篇 |
2006年 | 28篇 |
2005年 | 43篇 |
2004年 | 42篇 |
2003年 | 45篇 |
2002年 | 48篇 |
2001年 | 12篇 |
2000年 | 10篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1994年 | 3篇 |
1992年 | 5篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1977年 | 3篇 |
1971年 | 5篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 4篇 |
1967年 | 3篇 |
1966年 | 4篇 |
1965年 | 2篇 |
1959年 | 2篇 |
1958年 | 4篇 |
1957年 | 2篇 |
排序方式: 共有793条查询结果,搜索用时 15 毫秒
1.
Variability in the performance of juvenile Chinook salmon is explained primarily by when and where they resided in estuarine habitats
下载免费PDF全文
![点击此处可从《Ecology of Freshwater Fish》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Paul Chittaro Lyndal Johnson David Teel Paul Moran Sean Sol Kate Macneale Richard Zabel 《Ecology of Freshwater Fish》2018,27(3):857-873
Estuarine habitats provide rearing opportunities for the juvenile life stage of anadromous fishes. Because survival is positively correlated with juvenile performance, these estuarine habitats play an important role in population abundance and productivity. To provide information for the recovery of several depressed stocks of Chinook salmon in the Columbia River Basin, we sought to identify the factors that explain variability in performance. Using otolith‐derived estimates of juvenile somatic growth rate as an index of recent performance, we observed a negative nonlinear relationship between growth rate and day of year, and a decreasing and increasing trend of growth rate over the 8 years of this study and distance from the river mouth respectively. Using a generalised linear modelling approach, we found that variability in juvenile somatic growth rate was best explained by where and when individuals were collected, their body size, contaminant loads, stock of origin, and whether a fish was hatchery produced or unmarked. Lastly, we argue that a considerable improvement to the growth rate of juveniles in estuarine habitats is physiologically possible. The results of this 8‐year study provide a baseline of the performance of juvenile Chinook salmon to evaluate habitat restoration programs and to compare against future anthropogenic conditions. 相似文献
2.
A technique is described for biopsy of the bovine udder, employing sedation and local anaesthesia. Tissue samples of approximately 5 g were obtained by electrocautery from two quarters of the udder of a cow laterally recumbent. Care was taken to ensure complete haemostasis which was achieved by electrocoagulation and ligation. Postoperative recovery was rapid, and loss of yield was no greater in biopsied glands than in control glands of the same cow. Yield from all quarters returned to preoperative levels within 48 h. 相似文献
3.
Diagnosis of mastitis for therapy decisions. 总被引:2,自引:0,他引:2
Philip M Sears Kate K McCarthy 《Veterinary Clinics of North America: Food Animal Practice》2003,19(1):93-108, vi
Identifying specific groups of mastitis pathogens by their growth on selective agars can help identify the pathogens that are present in mastitic milk samples. This article addresses issues that are essential in making good use of diagnostic procedures to improve udder health on dairies. 相似文献
4.
On a property in the Nelson District, blood and urine samples were taken from red deer (Cervus elaphus) from which low (<1:100) antibody titres to serovar copenhageni and suspected leptospiral abortions had previously been reported. A total of 27 hinds were sampled. Microscopic agglutination test (MAT) titres in sera ranging from 1:32 to 1:128 were found in six animals. Thirteen leptospiral isolations were made from nine of the 27 urine samples. Four of these were typed as copenhageni and nine as hardjo. Two cultures were prepared from each urine sample and hardjo and copenhageni were both isolated from single urine samples from two animals. None of the 27 deer had serum MAT titres at 1:32 or above to copenhageni. 相似文献
5.
6.
7.
Stefan Möth Markus Redl Silvia Winter Florian Hüttner Siegrid Steinkellner 《Pest management science》2023,79(9):3080-3089
BACKGROUND
A reduction in chasmothecia, an important inoculum of grape powdery mildew (Erysiphe necator Schwein.), is essential for disease control in vineyards; the use of fungicides during the formation of chasmothecia on vine leaves, late in the growing season, may accomplish this. Inorganic fungicides, such as sulphur, copper, and potassium bicarbonate, are very useful for this purpose because of their multisite mode of action. The aim of this study was to evaluate chasmothecia reduction using different fungicide applications late in the growing season in commercially managed vineyards and in an exact application trial.RESULTS
Chasmothecia on vine leaves were reduced in commercial vineyards by four copper (P = 0.01) and five potassium bicarbonate (P = 0.026) applications. The positive effect of potassium bicarbonate was also confirmed in the application trial, where two applications showed lower chasmothecia numbers than the control (P = 0.002).CONCLUSION
The application of inorganic fungicides reduced the amount of chasmothecia as the primary inoculum source. Potassium bicarbonate and copper are of further interest for disease control as these fungicides can be used by organic and conventional wine growers. The application of these fungicides should be carried out as late as possible before harvest to reduce chasmothecia formation and, consequently, the potential for powdery mildew infestation in the subsequent season. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. 相似文献8.
Kate L. Constantine Fernadis Makale Idah Mugambi Duncan Chacha Harrison Rware Alexander Muvea Vincent K. Kipngetich Justice Tambo Adewale Ogunmodede Djami Djeddour Corin F. Pratt Ivan Rwomushana Frances Williams 《Pest management science》2023,79(11):4343-4356
Background
In Kenya, rice (Oryza sativa L.) is mainly produced under irrigation by small-scale farmers. Mwea irrigation scheme (MIS) in Kirinyaga County accounts for 80–88% of rice production. Here, rice is the main source of livelihood and a source of revenue generation for the county. However, a recently established invasive freshwater snail, Pomacea canaliculata (Lamarck) (family: Ampullariidae), a species of apple snail, presents a serious threat to rice production.Results
Household surveys, focus group discussions and key informant interviews highlight apple snail as a serious problem in MIS. Households that observed at least a moderate level of infestation (>20% of cultivated area) experienced significant reductions in rice yield (~14%) and net rice income (~60%). Farmers reported increased use of chemical pesticides for management of apple snail. In addition, the cost of hired labor for physical removal of egg masses and snails is resulting in substantial negative effects on net income. Farmer age, area of land owned, responsibility for decision-making, receipt of extension advice, training, and membership of a farmer organization, were all statistically significant variables to explain farmers awareness of the need for area-wide apple snail management.Conclusion
Strategies to limit the spread of apple snail are urgently needed. A Multi-Institutional Technical Team (MITT) has been established to spearhead management efforts and consolidate advice to farmers on how to manage apple snail. However, without action to mitigate spread, the consequences could be disastrous for rice production and food security in Kenya, and for other rice growing regions across Africa. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. 相似文献9.
10.