全文获取类型
收费全文 | 833篇 |
免费 | 33篇 |
专业分类
林业 | 40篇 |
农学 | 31篇 |
基础科学 | 15篇 |
94篇 | |
综合类 | 149篇 |
农作物 | 39篇 |
水产渔业 | 21篇 |
畜牧兽医 | 389篇 |
园艺 | 48篇 |
植物保护 | 40篇 |
出版年
2023年 | 7篇 |
2021年 | 9篇 |
2018年 | 10篇 |
2017年 | 7篇 |
2016年 | 16篇 |
2015年 | 13篇 |
2014年 | 15篇 |
2013年 | 35篇 |
2012年 | 17篇 |
2011年 | 32篇 |
2010年 | 18篇 |
2009年 | 29篇 |
2008年 | 20篇 |
2007年 | 34篇 |
2006年 | 31篇 |
2005年 | 28篇 |
2004年 | 26篇 |
2003年 | 23篇 |
2002年 | 26篇 |
2001年 | 21篇 |
2000年 | 24篇 |
1999年 | 21篇 |
1998年 | 16篇 |
1997年 | 5篇 |
1996年 | 6篇 |
1995年 | 10篇 |
1994年 | 10篇 |
1992年 | 17篇 |
1991年 | 19篇 |
1990年 | 22篇 |
1989年 | 30篇 |
1988年 | 13篇 |
1987年 | 12篇 |
1986年 | 17篇 |
1985年 | 17篇 |
1984年 | 14篇 |
1983年 | 24篇 |
1982年 | 8篇 |
1981年 | 6篇 |
1979年 | 7篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1975年 | 10篇 |
1974年 | 7篇 |
1973年 | 8篇 |
1972年 | 8篇 |
1970年 | 10篇 |
1969年 | 5篇 |
1968年 | 6篇 |
1956年 | 5篇 |
排序方式: 共有866条查询结果,搜索用时 0 毫秒
21.
22.
23.
Mixtures of tri-S-butyl phosphorotrithioate (DEF) emulsion and the potassium salt of picloram were strongly synergistic when applied as foliar sprays to pot-grown privet, poplar, guava and Eucalyptus plants. A similar but less marked effect was observed in privet, using mixtures of DEF and a water-soluble amine formulation of 2,4,5-T. By contrast, mixtures of an oil-soluble ester formulation of 2,4,5-T with DEF were antagonistic with privet. 相似文献
24.
25.
26.
Radford AD Stockley P Taylor IR Turner R Gaskell CJ Kaney S Humphris G Magrath C 《The Veterinary record》2003,152(14):422-427
A course in communication skills has been developed specifically for veterinary students, based on those delivered at many medical schools, and making extensive use of professional actors as simulated clients. Its aim is to raise awareness of the importance of communication among veterinary undergraduates at all stages of the curriculum, and it allows them to role-play in acted-out scenarios. Facilitated small groups provide an environment in which students can receive feedback on their own performance and also give feedback to their colleagues. An independent evaluation suggests that the opportunity to role-play increased the students' confidence in communicating with others. They were able to identify their personal strengths as communicators and gain insights into the aspects of communication they could improve. Feedback and subsequent discussions were highly valued, with the actors playing a crucial role in providing feedback from the client's perspective. Students were able to use the knowledge they acquired when consulting with real clients. Most of the students suggested that the course should continue in its current format, but with more time provided for it in the curriculum. 相似文献
27.
Ninety-five pigs (initially 7.1 kg and 24 d of age) were used in a 28-d experiment to determine the effects of Ascophyllum nodosum seaweed extract (ANOD) on young pig growth performance and immune function in response to enteric disease challenge with Salmonella typhimurium (ST). Experimental treatments were arranged in a 2 x 4 factorial with main effects of disease challenge (control vs ST-challenge) and dietary addition of ANOD (0, 0.5, 1.0, and 2.0% of diet). Pigs were fed ANOD diets for 14 d and then challenged orally with ST or sterile media. There were no main effects of ANOD on growth performance end points, although there were significant quadratic effects of ANOD on ADG (P < 0.04) and final weight (P < 0.003), both being greatest at 1.0% ANOD. There was a positive linear effect of ANOD inclusion on ADFI (P < 0.07) and a negative linear effect on the gain-to-feed ratio (G/F) (P < 0.05). ST-challenge reduced ADG (P < 0.05), ADFI (P < 0.05), and G/F (P < 0.05) in the first week following challenge. Daily estimates revealed reductions in feed intake in ST-infected pigs on d 2 to 4 following infection (P < 0.05). Rectal temperature was increased maximally 2 d following ST-infection (P < 0.05). A disease challenge x time interaction (P < 0.001) was observed for serum haptoglobin and alpha1-acid glycoprotein. Serum immunoglobulin M (IgM) was not influenced by disease challenge, but IgM declined (P < 0.001) in all pigs over time. Serum immunoglobulin G (IgG) also was not influenced by disease challenge, but IgG tended (P < 0.08) to increase over time. In vitro culture of porcine alveolar macrophages with 10 mg/mL ANOD elevated (P < 0.05) prostaglandin E2 (PGE2) production over that of controls at 3 and 24 h of culture. There was no interleukin-10 response by porcine splenocytes cultured in vitro with 0.005, 0.05, 0.5, or 5 mg/mL ANOD. We conclude that this model of enteric disease elicits an acute phase response that is accompanied by increased rectal temperature and diminished feed intake. Furthermore, our results indicate some beneficial effects of dietary ANOD on growth performance and no influence of dietary ANOD on immune response in the presence or absence of ST-challenge. However, high ANOD concentrations are capable of activating porcine alveolar macrophages in vitro to secrete PGE2. 相似文献
28.
Improved understandings of the agricultural and range ecologies ofsemi-arid Africa require better information on the spatiotemporal distributionof domestic livestock across agropastoral landscapes. An empirical GIS-basedapproach was developed for estimating distributions of herded livestock acrossthree agropastoral territories (around 100 km2 each)over a two-year period. Algorithms developed from regression analyses of herdtracking data (with R2s 0.67) are used to transform a morecomprehensive but incomplete set of data generated from herders accounts oftheir herds grazing itineraries (400 herds following 6500 itineraries). Theresulting characterization registers 40 000 days of livestock activitiesacross694 land units (averaging 70 ha) over the study period. This studydemonstrates that rural producers knowledge of their daily extractionpracticescan be translated to fine-grained characterizations of extraction densitiesacross mixed landscapes. The spatiotemporal distribution of livestock that isrevealed by this approach diverges strongly from that predicted bycommonly-usedpoint-diffusion estimation procedures. Instead, the distribution reflects localpatterns of land use, topography, vegetation, settlements, and water points.Grazing and nongrazing times spent in land units are not spatially correlatedand the seasonality of grazing pressure is spatially variable. Therefore, theecological impacts of livestock grazing are spatially variable at fine scalesand there is a significant potential for livestock-mediated nutrient transfersacross agropastoral landscapes. The georeferenced data produced by thisapproachnot only will help evaluate the impact and sustainability of differentmanagement practices but also provides a strong empirical base for improvedspatial modeling of herded livestock.This revised version was published online in May 2005 with corrections to the Cover Date. 相似文献
29.
AIM: The purpose of this study was to obtain information on aspects of dogs' lifestyle and diet that may be related to flatulence, whether the dogs were flatulent or not and if the owners were concerned about flatulence of their pet. METHODS: The owners of 110 pet dogs were randomly selected from the Massey University clinic tiles and asked to complete a questionnaire relating to their dog's flatulence, lifestyle and diet. RESULTS: Flatulence was detected by 47 owners and occurred more often in less active inside dogs than those exercised more often. No individual food or dietary association was identified. Nineteen of the 47 owners of flatulent dogs would alter their dog's diet if that change would reduce flatulence. CONCLUSION: Flatulence occurs in pet dogs and most owners accept flatulence and were unconcerned about its consequence. 相似文献
30.