全文获取类型
收费全文 | 354篇 |
免费 | 11篇 |
国内免费 | 1篇 |
专业分类
林业 | 11篇 |
农学 | 9篇 |
基础科学 | 2篇 |
21篇 | |
综合类 | 179篇 |
农作物 | 4篇 |
水产渔业 | 9篇 |
畜牧兽医 | 114篇 |
园艺 | 13篇 |
植物保护 | 4篇 |
出版年
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 3篇 |
2018年 | 6篇 |
2017年 | 3篇 |
2016年 | 6篇 |
2015年 | 3篇 |
2014年 | 4篇 |
2013年 | 15篇 |
2012年 | 11篇 |
2011年 | 7篇 |
2010年 | 6篇 |
2009年 | 12篇 |
2008年 | 10篇 |
2007年 | 20篇 |
2006年 | 12篇 |
2005年 | 9篇 |
2004年 | 9篇 |
2003年 | 4篇 |
2002年 | 9篇 |
2001年 | 6篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 8篇 |
1990年 | 4篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 7篇 |
1982年 | 4篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1970年 | 2篇 |
1969年 | 4篇 |
1960年 | 3篇 |
1959年 | 17篇 |
1958年 | 35篇 |
1957年 | 32篇 |
1952年 | 3篇 |
1948年 | 2篇 |
1945年 | 2篇 |
1944年 | 2篇 |
1939年 | 2篇 |
1938年 | 2篇 |
1937年 | 2篇 |
排序方式: 共有366条查询结果,搜索用时 278 毫秒
51.
52.
53.
54.
Thompson H 《The Veterinary record》2006,159(17):570-1; discussion 571
55.
56.
Antioxidant vitamins are commonly used as colorant, preventive, sweetener, nutritive and antioxidant materials in food industry. Thus, many studies have been conducted in recent years. We have performed the present study to understand the effects of α-lipoic acid (ALA), vitamin C and E, added into rations of Japanese quails, on chronic heat stress. This study was carried out in five groups as: control, stress, ALA, vitamin E and vitamin C groups. Heat stress is applied to all groups except the control group. Superficial pectoral muscles tissues were used for biochemical determinations. During the research, it is found that heat stress exerted undesired effects such as increasing lipid peroxidation (LPO) level indicating oxidative stress in Japanese quails. In addition, superoxide dismutase (SOD) and catalase (CAT) enzyme activities and glutathione (GSH) amounts were studied to understand the behaviour of defence mechanism. While stress increased LPO ratio, it was determined that all antioxidant added into the ration decreases LPO significantly (p < 0.05). In addition, it was determined that all of antioxidants added into ration effectively restored SOD activity and LPO ratio which heat stress affected negatively. Interestingly, vitamin C did not adjust GSH ratio in contrast to vitamin E and ALA, where vitamin E and C did not perform any positive effect on heat stress decreased CAT activity. Finally, it can be thought that antioxidant vitamins relatively ameliorated these undesired affects caused by stress factors given. 相似文献
57.
Joshua A. Stern Jeremy R. Tobias Bruce W. Keene 《Journal of Veterinary Cardiology》2012,14(4):537-539
Third degree atrioventricular (AV) block was observed in a patient with a roughly spherical mass measuring approximately 1 × 1 × 1 cm, visible in the basilar portion of the interventricular septum on 2-dimensional transthoracic echocardiographic examination. The patient had a brief history of lethargy and episodic collapse, and the owner elected to euthanize the dog after the mass lesion was discovered. Necropsy revealed multiple masses within the interventricular septum, ventricular free walls and atrial myocardium. The final diagnosis was large cell (T-cell) lymphosarcoma. 相似文献
58.
We examined key drivers of deforestation in the Lake Victoria Crescent, Uganda from 1989 to 2009 through a case study approach with a multiple-case design. Nineteen focus groups with local community members and forest officials, archival analysis, and field observation revealed both proximate causes and underlying drivers of deforestation. Proximate causes of deforestation included agricultural expansion into forests, unsustainable extraction of wood forest products, and clearing of forests for nonagricultural uses. Underlying drivers of these proximate causes included policy and institutional factors, economic factors, population growth, technological changes, and changes in culture—each resulting in alienation of local people from forest resources. Alienation of local people, defined as a psychological dispossession of responsibility for forest resources, is posited as the most important underlying driver of deforestation. We discuss the importance of the involvement of local people in the management and maintenance of forests in the Lake Victoria Crescent. 相似文献
59.
Schukken YH González RN Tikofsky LL Schulte HF Santisteban CG Welcome FL Bennett GJ Zurakowski MJ Zadoks RN 《Veterinary microbiology》2009,134(1-2):9-14
In this paper, we analyzed a very large field data set on intramammary infections (IMI) and the associated somatic cell count (SCC) in dairy cows. The objective of the study was to analyze the impact of coagulase-negative staphylococci (CNS) IMI on cow SCC, both mean and variability, and on the potential of these infections to have a major impact on the bulk milk SCC (BMSCC). Data and milk samples for bacterial culture were collected by Quality Milk Production Services (QMPS) between 1992 and March of 2007. The QMPS program services dairy farms in New York State and other states in the Northeastern USA and operates in conjunction with Cornell University. Only records from cows where SCC and milk production data were available, and where only one organism was isolated from bacterial cultures of milk samples (or where culture was negative) were used for this analysis. A total of 352,614 records from 4200 whole herd mastitis screening sampling qualified for this study. Within herds an average of 15% (S.D. 12%) of cows sampled were infected with CNS, ranging between 0 and 100%. Average within herd prevalence of cows with a CNS IMI and an SCC over 200,000 cells/ml was 2% (S.D. 4%) with a minimum of 0% and a maximum of 50%. Results of linear mixed models showed three distinct populations of IMI statuses: negative cultures with the lowest SCC; CNS and Corynebacterium bovis with a moderate increase in SCC, and Streptococcus agalactiae, Streptococcus spp. and Staphylococcus aureus showing an important increase in SCC. Surprisingly, milk production was slightly but significantly higher in CNS infected cows compared to culture-negative cows, whereas it was strongly reduced in cows with a major pathogen IMI. The percentage contribution of CNS infections to the BMSCC was 17.9% in herds with a BMSCC less than 200,000 cells/ml. This value decreased to 11.9 and 7.9% in herds with bulk milk SCC between 200,000 and 400,000 and over 400,000 cells/ml, respectively. We concluded that very few herds with milk quality problems would have an important increase in BMSCC that could be mostly attributed to CNS infections. On the other hand, in herds with low BMSCC, CNS infections may be an important contributor to the total number of somatic cells in the bulk milk. 相似文献
60.
Melena J Bayot B Betancourt I Amano Y Panchana F Alday V Calderón J Stern S Roch P Bonami JR 《Journal of fish diseases》2006,29(10):589-600
Larvae and post-larvae of Penaeus vannamei (Boone) were submitted to primary challenge with infectious hypodermal and haematopoietic necrosis virus (IHHNV) or formalin-inactivated white spot syndrome virus (WSSV). Survival rate and viral load were evaluated after secondary per os challenge with WSSV at post-larval stage 45 (PL45). Only shrimp treated with inactivated WSSV at PL35 or with IHHNV infection at nauplius 5, zoea 1 and PL22 were alive (4.7% and 4%, respectively) at 10 days post-infection (p.i.). Moreover, at 9 days p.i. there was 100% mortality in all remaining treatments, while there was 94% mortality in shrimp treated with inactivated WSSV at PL35 and 95% mortality in shrimp previously treated with IHHNV at N5, Z1 and PL22. Based on viral genome copy quantification by real-time PCR, surviving shrimp previously challenged with IHHNV at PL22 contained the lowest load of WSSV (0-1x10(3) copies microg-1 of DNA). In addition, surviving shrimp previously exposed to inactivated WSSV at PL35 also contained few WSSV (0-2x10(3) copies microg-1 of DNA). Consequently, pre-exposure to either IHHNV or inactivated WSSV resulted in slower WSSV replication and delayed mortality. This evidence suggests a protective role of IHHNV as an interfering virus, while protection obtained by inactivated WSSV might result from non-specific antiviral immune response. 相似文献