全文获取类型
收费全文 | 926篇 |
免费 | 44篇 |
国内免费 | 4篇 |
专业分类
林业 | 38篇 |
农学 | 19篇 |
基础科学 | 1篇 |
177篇 | |
综合类 | 98篇 |
农作物 | 30篇 |
水产渔业 | 68篇 |
畜牧兽医 | 475篇 |
园艺 | 24篇 |
植物保护 | 44篇 |
出版年
2023年 | 5篇 |
2022年 | 11篇 |
2021年 | 14篇 |
2020年 | 30篇 |
2019年 | 29篇 |
2018年 | 22篇 |
2017年 | 24篇 |
2016年 | 24篇 |
2015年 | 18篇 |
2014年 | 29篇 |
2013年 | 43篇 |
2012年 | 54篇 |
2011年 | 73篇 |
2010年 | 32篇 |
2009年 | 40篇 |
2008年 | 55篇 |
2007年 | 62篇 |
2006年 | 51篇 |
2005年 | 58篇 |
2004年 | 47篇 |
2003年 | 38篇 |
2002年 | 43篇 |
2001年 | 11篇 |
2000年 | 15篇 |
1999年 | 11篇 |
1998年 | 7篇 |
1997年 | 12篇 |
1996年 | 6篇 |
1995年 | 13篇 |
1994年 | 6篇 |
1993年 | 7篇 |
1992年 | 3篇 |
1991年 | 13篇 |
1990年 | 13篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 6篇 |
1977年 | 2篇 |
1973年 | 4篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有974条查询结果,搜索用时 31 毫秒
821.
Corneal squamous cell carcinoma in a Border Collie 总被引:1,自引:1,他引:0
A 6-year-old, female, spayed Border Collie was presented to the Unit of Comparative Ophthalmology at the Animal Health Trust with a 6-month history of a progressive nonpainful opacity of the left cornea. A keratectomy was performed and the tissue submitted for histopathology. The diagnosis was squamous cell carcinoma. There has been no recurrence of the neoplasm to date (5 months). Canine corneal squamous cell carcinoma (SCC) has not been reported previously in the UK. 相似文献
822.
823.
Mateus de Souza Ribeiro Mioni Bruna Letícia Devid Ribeiro Marina Gea Peres Wanderson Sirley Reis Teixeira Vanessa Cristina Pelícia Rodrigo Garcia Motta Marcelo Bahia Labruna Mrcio Garcia Ribeiro Karim Sidi‐Boumedine Jane Megid 《Zoonoses and public health》2019,66(6):695-700
Coxiella burnetii is a zoonotic pathogen with a worldwide distribution that is responsible for Q fever in humans. It is a highly infectious bacterium that can be transmitted from cattle to humans through the consumption of unpasteurized milk. We report the molecular identification of C. burnetii in raw cow's milk being sold directly for human consumption in Brazil without official inspection or pasteurization. One hundred and twelve samples of raw milk were analysed by real‐time quantitative PCR (qPCR), and C. burnetii was detected in 3.57% (4/112) of the samples at a concentration ranging from 125 to 404 bacteria per millilitre. The identification of this zoonotic pathogen in raw milk sold directly for human consumption is a public health concern since C. burnetii can be transmitted through the oral route. This result indicates that health education and other preventive measures should be officially implemented in Brazil to prevent the spread of infection. To our knowledge, this is the first qPCR‐based detection of C. burnetii in raw milk samples from cows sold in Brazil that do not undergo official inspection or pasteurization. 相似文献
824.
825.
826.
This report describes a dog with recurrent atrial fibrillation and atrial flutter associated with chronic gastritis. Although no underlying structural heart disease was apparent antemortem or on gross post-mortem examination, chronic atrial myocarditis was seen on histopathological examination. Atrial myocarditis is a recognised cause of atrial fibrillation in human beings with presumed lone fibrillation, and an association between supraventricular tachyarrhythmias and infectious agents has been made. 相似文献
827.
Albuquerque MR Silveira ER De A Uchôa DE Lemos TL Souza EB Santiago GM Pessoa OD 《Journal of agricultural and food chemistry》2004,52(22):6708-6711
The volatile composition of the essential oils from leaves and roots of Eupatorium betonicaeforme (D.C.) Baker was analyzed by GC-MS. A total of 12 compounds were identified. beta-Caryophyllene (12.4-41.7%), alpha-humulene (11.7-14.6%), gamma-muurolene (10.4-19.0%), bicyclogermacrene (15.0-17.5%), 2,2-dimethyl-6-vinylchroman-4-one (10.3-25.5%), and 2-senecioyl-4-vinylphenol (8.5-41.0%) were the most prominent constituents. The former two compounds were isolated and characterized by spectroscopic data. The essential oils and the isolated compounds were tested against Aedes aegypti larvae survival. The results obtained show that the essential oil from roots and 2,2-dimethyl-6-vinylchroman-4-one (10.3-25.5%) could be considered as natural larvicidal agents. 相似文献
828.
Jane S. Kemp Eric Paterson Shimna M. Gammack Malcolm S. Cresser Kenneth Killham 《Biology and Fertility of Soils》1992,13(4):218-224
Summary The effects of soil temperature and bulk soil pH on the vertical translocation of a genetically modified Pseudomonas fluorescens inoculum were studied in reconstituted soil microcosms, in the presence and absence of growing Lolium perenne roots. The inoculated microcosms received one rainfall event per day (5 mm h-1 for 6 h) for 5 days and the resulting leachate was quantitatively assayed for the presence of the modified pseudomonad. Soil temperature affected the total number of modified pseudomonads detected in the leachate over the 5 days, with significantly lower numbers detected at 25°C compared to 5°C. The bulk soil pH also affected leaching of the inoculum, with significantly greater numbers detected in the effluent at pH 7.5 than at pH 4.5. In the absence of L. perenne, greater numbers of the modified pseudomonads were detected in the pH 7.5 soil after 5 days of leaching compared to soil at pH 4.5. L. perenne roots decreased the number of cells of the inoculum that were leached and detected in the soil after 5 days of leaching. In the soil microcosms used for the pH study the distribution of the inoculum remaining with the soil was altered by L. perenne roots. At each pH value the proportion of cells detected within the soil below the surface 2 cm of the microcosms was greater in the presence of L. perenne roots. The results of this study indicate that soil temperature, bulk soil pH, and the presence of root systems are important factors in determining the extent of inoculum translocation, and should be considered in the design and interpretation of field experiments. 相似文献
829.
Robin Jane Roff 《Agriculture and Human Values》2009,26(4):351-363
Third-party certification is an increasingly prevalent tactic which agrifood activists use to “help” consumers shop ethically,
and also to reorganize commodity markets. While consumers embrace the chance to “vote with their dollar,” academics question
the potential for labels to foster widespread political, economic, and agroecological change. Yet, despite widespread critique,
a mounting body of work appears resigned to accept that certification may be the only option available to activist groups
in the context of neoliberal socio-economic orders. At the extreme, Guthman (Antipode 39(3): 457, 2007) posits that “at this political juncture… ‘there is no alternative.” This paper offers a different assessment of third-party
certification, and points to interventions that are potentially more influential that are currently available to activist
groups. Exploring the evolution of the Non-GMO Project—a novel certification for foods that are reasonably free of genetically
engineered (GE) material—I make two arguments. First, I echo the literature’s critical perspective by illustrating how certification
projects become vulnerable to industry capture. Reviewing its history and current context, I suggest that the Non-GMO Project
would be better suited to helping companies avoid mounting public criticism than to substantially reorient agrifood production.
Second, I explore the “politics of the possible” in the current political economy and argue that while neoliberalization and
organizers’ places within the food system initially oriented the group towards the private sector, the choice to pursue certification
arose directly from two industry partnerships. Consequently, current trends might favor market mechanisms, but certification
is only one possible intervention that has emerged as a result of particular, and perhaps avoidable, circumstances. The article
offers tentative delineation of alternatives ways that activists might intervene in agrifood and political economic systems
given present constraints. 相似文献
830.
Muir JG Shepherd SJ Rosella O Rose R Barrett JS Gibson PR 《Journal of agricultural and food chemistry》2007,55(16):6619-6627
Fructans are not digested in the small intestines of humans. While many health benefits have been attributed to these carbohydrates, they can cause gastrointestinal symptoms in some individuals. We measured the total fructans in 60 vegetables and 43 fruits using the Megazyme fructan assay. Vegetables with the highest quantity of fructans included garlic, artichoke, shallots, leek bulb, and onions (range, 1.2-17.4 g/100 g fw). Fruits with low, but detectable, fructans included longon, white peach, persimmon, and melon (range, 0.21-0.46 g/100 g fw). The fructan assay was modified to provide an estimate of the average chain length (degree of polymerization) for high fructan vegetables. d-Fructose can also be malabsorbed in the small intestine of humans, so the d-fructose content in some foods was measured to supplement the current food tables. Research in this area will be facilitated through the availability of more comprehensive food composition data. 相似文献