全文获取类型
收费全文 | 170篇 |
免费 | 13篇 |
国内免费 | 2篇 |
专业分类
林业 | 3篇 |
农学 | 2篇 |
38篇 | |
综合类 | 15篇 |
农作物 | 3篇 |
水产渔业 | 1篇 |
畜牧兽医 | 112篇 |
园艺 | 2篇 |
植物保护 | 9篇 |
出版年
2024年 | 1篇 |
2021年 | 1篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 6篇 |
2017年 | 3篇 |
2016年 | 3篇 |
2015年 | 7篇 |
2014年 | 6篇 |
2013年 | 7篇 |
2012年 | 7篇 |
2011年 | 13篇 |
2010年 | 4篇 |
2009年 | 10篇 |
2008年 | 5篇 |
2007年 | 11篇 |
2006年 | 5篇 |
2005年 | 3篇 |
2004年 | 3篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 8篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 4篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1970年 | 1篇 |
1934年 | 1篇 |
排序方式: 共有185条查询结果,搜索用时 271 毫秒
51.
The relative influence of thermal and quantum fluctuations on the proton transfer properties of the charged water complexes H5O2+ and H3O2- was investigated with the use of ab initio techniques. These small systems can be considered as prototypical representatives of strong and intermediate-strength hydrogen bonds. The shared proton in the strongly hydrogen bonded H5O2+ behaved in an essentially classical manner, whereas in the H3O2- low-barrier hydrogen bond, quantum zero-point motion played a crucial role even at room temperature. This behavior can be traced back to a small difference in the oxygen-oxygen separation and hence to the strength of the hydrogen bond. 相似文献
52.
53.
Aspirin: intestinal damage in rats 总被引:1,自引:0,他引:1
Lesions induced by aspirin in the small intestine of the rat were visualized after 4 hours by the intravenous administration of a 5 percent solution of pontamine sky blue, 6 BX dye. Dose-response curves in fasted and fed rats indicated that the fed rat was about eight times more susceptible to aspirin-induced intestinal damage than was the fasted rat, while the fasted rat was about 13 times more susceptible to aspirin-induced gastric damage than was the fed rat. 相似文献
54.
55.
Afforestation and reforestation of pastures are key land-use changes in New Zealand that help sequester carbon (C) to offset its carbon dioxide (CO2) emissions under the Kyoto Protocol. However, relatively little attention has been given so far to associated changes in trace gas fluxes. Here, we measure methane (CH4) fluxes and CO2 production, as well as microbial C, nitrogen (N) and mineral-N, in intact, gradually dried (ca. 2 months at 20 °C) cores of a volcanic soil and a heavier textured, non-volcanic soil collected within plantations of Pinus radiata D. Don (pine) and adjacent permanent pastures. CH4 fluxes and CO2 production were also measured in cores of another volcanic soil under reverting shrubland (mainly Kunzea var. ericoides (A. Rich) J. Thompson) and an adjacent pasture. CH4 uptake in the pine and shrubland cores of the volcanic soils at field capacity averaged about 35 and 14 μg CH4-C m−2 h−1, respectively, and was significantly higher than in the pasture cores (about 21 and 6 μg CH4-C m−2 h−1, respectively). In the non-volcanic soil, however, CH4-C uptake was similar in most cores of the pine and pasture soils, averaging about 7-9 μg m−2 h−1, except in very wet samples. In contrast, rates of CO2 production and microbial C and N concentrations were significantly lower under pine than under pasture. In the air-dry cores, microbial C and N had declined in the volcanic soil, but not in the non-volcanic soil; ammonium-N, and especially nitrate-N, had increased significantly in all samples. CH4 uptake was, with few exceptions, not significantly influenced by initial concentrations of ammonium-N or nitrate-N, nor by their changes on air-drying. A combination of phospholipid fatty acid (PLFA) and stable isotope probing (SIP) analyses of only the pine and pasture soils showed that different methanotrophic communities were probably active in soils under the different vegetations. The C18 PLFAs (type II methanotrophs) predominated under pine and C16 PLFAs (type I methanotrophs) predominated under pasture. Overall, vegetation, soil texture, and water-filled pore space influenced CH4-C uptake more than did soil mineral-N concentrations. 相似文献
56.
57.
58.
59.
O O Opara L E Carr E Russek-Cohen C R Tate E T Mallinson R G Miller L E Stewart R W Johnston S W Joseph 《Avian diseases》1992,36(3):664-671
Three flocks on 13 different broiler farms were monitored for Salmonella over three consecutive growout periods using the drag swab (DS) technique. One house was consistently negative for Salmonella contamination (7.7%); four houses were consistently positive (30.8%); and eight houses (61.5%) alternated between either a DS Salmonella-negative or -positive status. Simultaneously, numerous environmental parameters of the litter surface were measured, including water activity (Aw), ammonia, temperature, pH, moisture content (MC), ash content, and volatile solids. Analysis of these data as a corollary to either Salmonella-negative or -positive DS results revealed significant correlation coefficients for some of the parameters, especially Aw. The results suggest that there should be further exploration of remedial intervention based on control of some of the physical features of litter (e.g., controlling litter Aw and possibly MC and pH levels) in poultry houses. 相似文献
60.
K F Bowman C L Sweeney L P Tate 《Journal of the American Veterinary Medical Association》1987,190(3):305-307
A medial condylar fracture of the third metatarsal bone in a 2-year-old Thoroughbred filly was repaired successfully by use of compression bone plating. At discharge from the hospital, thickening of the metatarsus was evident, and proliferative changes were associated with the site of bone plate application. It was expected that these changes would limit the filly's use as a racehorse, and a return to training was not recommended. Especially in horses that may return to racing, use of compression bone plating initially should not replace stall rest or lag screw fixation treatment of this type of injury. However, the use of a similar approach in selected cases of medial condylar fracture of the third metatarsal bone is encouraged, especially when additional fissure lines are evident on radiographs. 相似文献