全文获取类型
收费全文 | 374篇 |
免费 | 23篇 |
专业分类
林业 | 3篇 |
农学 | 13篇 |
63篇 | |
综合类 | 33篇 |
农作物 | 23篇 |
水产渔业 | 10篇 |
畜牧兽医 | 201篇 |
园艺 | 10篇 |
植物保护 | 41篇 |
出版年
2019年 | 4篇 |
2018年 | 11篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 8篇 |
2013年 | 49篇 |
2012年 | 6篇 |
2011年 | 8篇 |
2010年 | 6篇 |
2009年 | 7篇 |
2008年 | 10篇 |
2007年 | 11篇 |
2006年 | 5篇 |
2005年 | 5篇 |
2004年 | 9篇 |
2003年 | 10篇 |
2002年 | 12篇 |
2001年 | 6篇 |
2000年 | 5篇 |
1999年 | 7篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 8篇 |
1992年 | 9篇 |
1991年 | 9篇 |
1990年 | 5篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1985年 | 13篇 |
1983年 | 9篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 10篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1974年 | 3篇 |
1973年 | 10篇 |
1972年 | 4篇 |
1971年 | 7篇 |
1970年 | 6篇 |
1968年 | 9篇 |
1967年 | 4篇 |
1930年 | 4篇 |
1924年 | 3篇 |
排序方式: 共有397条查询结果,搜索用时 15 毫秒
91.
Effects of residual and reapplied biosolids on performance and mineral status of grazing beef steers 总被引:4,自引:0,他引:4
Tiffany ME Mcdowell LR O'Connor GA Martin FG Wilkinson NS Percival SS Rabiansky PA 《Journal of animal science》2002,80(1):260-269
An experiment was designed to assess the mineral status of 60 Angus yearling beef steers grazing bahiagrass pastures fertilized with large amounts of biosolids from three sources: Baltimore, MD; Tampa, FL; and Largo, FL. Biosolids were classified as exceptional quality and thus had no regulatory restrictions on loading rate. They differed primarily in concentration of Mo (12 to 56 mg/kg of DM). Residual treatments (biosolids applied only the previous year) for Baltimore biosolids were applied at 22.4 and 44.8 t/ha, and Tampa biosolids were either 16.8 or 33.6 t/ ha. The reapplied treatments (applied in consecutive years) for both Baltimore and Tampa sludges were applied at 22.4, 44.8, 16.8 , and 33.6 t/ha, respectively. The two Largo biosolids treatments were either 56 or 112 t/ha and were applied only in the 2nd yr. Liver biopsies and blood samples were collected on d 1, 95, and 180. Liver and plasma were analyzed for minerals and blood was analyzed for hemoglobin, hematocrit, and superoxide dismutase of polymorphonuclear neutrophils. Experimental animals were generally adequate in macromineral status and Co, Fe, and Mn throughout the experiment. Copper deficiency was evident based on the clinical signs of hair coat discoloration, very low plasma Cu at d 95, and the continuous decline in liver Cu over 180 d. A sharp decline in plasma Cu was observed for all treatments from d 1 to 95, after which Cu concentrations rebounded to normal concentrations (> 0.65 microg/mL) by d 180. Liver Mo was well below concentrations indicating toxicity (> 5.0 mg/kg). The steep decline in liver Cu over the first 95 d reflects the dietary Cu deficiency and the possibility of high forage S (0.26 to 0.52%) interfering with Cu metabolism. Biosolids application to bahiagrass pastures was not detrimental to mineral status except for declining Cu stores; however, the controls likewise declined, but to a lesser degree. 相似文献
92.
MF Ponzio JM Busso M Fiol de Cuneo RD Ruiz AA Ponce 《Reproduction in domestic animals》2008,43(2):228-233
The cryopreservation of spermatozoa constitutes a valuable tool for the captive breeding management of valuable and/or threatened species. Chinchilla lanigera is a species almost extinct in the wild, and the domestic counterpart has one of the most valuable pelts in the world. The objectives of this study were to: (i) compare the functional activity of post‐thawed chinchilla spermatozoa cryopreserved at ?196°C either with glycerol (G) or ethylene glycol (EG) as cryoprotectants (1 m final concentration) and (ii) investigate the effects of incubating the gametes for 4 h in the presence or in the absence of the cryoprotectants; evaluations were performed taking into account motility, viability, response to hypo‐osmotic shock and acrosome integrity of the cells. Parameters reflecting post‐thaw (0 h) sperm functional activity were significantly lower than those of freshly ejaculated gametes. When comparing the cryoprotectant efficiency of G vs EG, neither cryoprotectant agent offered appreciable advantages. After 4 h of incubation, in the presence or absence of the cryoprotectant agent, a rapid and significant decrease was found in all functional parameters and remained at ~ 20–30% motile, viable and viable acrosome intact cells. Viability was significantly lower when the cryoprotectant was removed from the media (possibly due to the centrifugation process). With respect to the maintenance of sperm membrane integrity, only ~ 10% of cells showed membrane resistance to hypo‐osmotic conditions after the 4 h incubation period. These results constitute new insights for cryopreservation protocols and the development of assisted reproductive techniques in this species. 相似文献
93.
94.
J. Michael Wilkinson Michael R. F. Lee M. Jordana Rivero A. Thomas Chamberlain 《Grass and Forage Science》2020,75(1):1-17
Grazing plays an important role in milk production in most regions of the world. In this review, some challenges to the grazing cow are discussed together with opportunities for future improvement. We focus on daily feed intake, efficiency of pasture utilization, output of milk per head, environmental impact of grazing and the nutritional quality to humans of milk produced from dairy cows in contrasting production systems. Challenges are discussed in the context of a trend towards increased size of individual herds and include limited and variable levels of daily herbage consumption, lower levels of milk output per cow, excessive excretion of nitrogenous compounds and requirements for minimal periods of grazing regardless of production system. A major challenge is to engage more farmers in making appropriate adjustments to their grazing management. In relation to product quality, the main challenge is to demonstrate enhanced nutritional/processing benefits of milk from grazed cows. Opportunities include more accurate diet formulations, supplementation of grazed pasture to match macro- and micronutrient supply with animal requirement and plant breeding. The application of robotics and artificial intelligence to pasture management will assist in matching daily supply to animal requirement. Wider consumer recognition of the perceived enhanced nutritional value of milk from grazed cows, together with greater appreciation of the animal health, welfare and behavioural benefits of grazing should contribute to the future sustainability of demand for milk from dairy cows on pasture. 相似文献
95.
There is little published information describing the differences in adrenal structure between strains of a single species despite quite well known functional differences. In this paper we report morphological differences in the adrenal glands between three strains of laboratory rat; Dark Agouti (DA), Sprague-Dawley (SD) and Wistar (W). Significant differences in adrenal weights (as a percentage of body weight) were not detected between any of the groups. While there were no significant differences in the volume of medullary or zonae glomerulosa or fasciculata tissue, the volume fraction for the zona reticularis was significantly smaller in DAs compared to the other strains. The functional significance of these differences is unknown. However, it is suggested that the reduced volume of zona reticularis tissue may contribute to a reduced capacity for glucocorticoid synthesis or storage. 相似文献
96.
Marston Christopher G. Wilkinson David M. Reynolds Sally C. Louys Julien O’Regan Hannah J. 《Landscape Ecology》2019,34(1):131-145
Landscape Ecology - The heterogeneous mosaic nature of African savannah vegetation is a key aspect of its ecology. This study evaluates mosaic distributions and characteristics across sub-Saharan... 相似文献
97.
98.
Antibacterial activity of raspberry cordial in vitro 总被引:1,自引:0,他引:1
Raspberry juice cordial has a long anecdotal use in Australia for the prophylaxis and treatment of gastroenteritis in livestock, cage birds and humans. The antimicrobial properties of raspberry juice cordial, raspberry juice, raspberry leaf extract and a commercial brand of raspberry leaf tea were investigated against five human pathogenic bacteria and two fungi. Raspberry cordial and juice were found to significantly reduce the growth of several species of bacteria, including Salmonella, Shigella and E. coli, but demonstrated no antifungal activity. No antimicrobial activity was detected in the leaf extract or tea. 相似文献
99.
F. C. Wilkinson 《Australian veterinary journal》1979,55(2):74-76
In a trial to ascertain the effect of dipping on dermatophilosis and production in Merino sheep it was found that sheep which had been dipped had more lesions and produced less wool than undipped sheep. Sheep dipped in water or water plus diazinon had more mortalities associated with dermatophilosis than sheep dipped in arsenic or not dipped. The arsenic appeared to aid healing. There were more mortalities in the sheep dipped in water or water plus diazinon one day after shearing than those dipped 10 days after shearing. 相似文献
100.
Three groups of animals were infected with three different African swine fever virus isolates. Antibody responses were measured, using immuno electro-osmophoresis, reverse single radial immunodiffusion and radioimmunoassay (RIA). The RIA detected antibody at 3–4 days whereas the diffusion tests did not detect it until 10 days post inoculation. Virus survival in different transport media was compared, using haemadsorption assays and RIA. Glycerinated medium reduced infectivity titres, although it had no effect on the ability of the RIA to detect antigen. 相似文献