全文获取类型
收费全文 | 541篇 |
免费 | 26篇 |
专业分类
林业 | 15篇 |
农学 | 18篇 |
基础科学 | 3篇 |
101篇 | |
综合类 | 67篇 |
农作物 | 59篇 |
水产渔业 | 52篇 |
畜牧兽医 | 205篇 |
园艺 | 12篇 |
植物保护 | 35篇 |
出版年
2023年 | 8篇 |
2022年 | 10篇 |
2021年 | 17篇 |
2020年 | 19篇 |
2019年 | 15篇 |
2018年 | 15篇 |
2017年 | 10篇 |
2016年 | 10篇 |
2015年 | 14篇 |
2014年 | 14篇 |
2013年 | 31篇 |
2012年 | 32篇 |
2011年 | 45篇 |
2010年 | 23篇 |
2009年 | 20篇 |
2008年 | 23篇 |
2007年 | 32篇 |
2006年 | 34篇 |
2005年 | 22篇 |
2004年 | 34篇 |
2003年 | 22篇 |
2002年 | 21篇 |
2001年 | 10篇 |
2000年 | 3篇 |
1998年 | 4篇 |
1996年 | 5篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1984年 | 2篇 |
1983年 | 6篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1966年 | 3篇 |
1959年 | 1篇 |
1956年 | 1篇 |
1954年 | 1篇 |
1938年 | 1篇 |
1937年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有567条查询结果,搜索用时 0 毫秒
41.
42.
The transmission of mucosal disease virus (MDV) from infected ewes and their lambs to susceptible sheep was investigated. MDV was recovered from the amniotic fluid of an infected pregnant ewe and from the blood, nasal swabs and urine of hairy lambs. MDV infection was transmitted either at lambing, from infective foetal fluids or lambs, or later as a result of contact with a surviving with a hairy lamb and either aborted or gave birth to an infected hairy lamb. Adult sheep and 12-months-old sheep were less readily infected than were newborn lambs. Pregnant ewes were infected by contact with a hairy lamb and either aborted or gave birth to an infected hairy lamb. A method to minimise spread of the infection in the field is suggested. 相似文献
43.
44.
Edwards LJ Goodship AE Birch HL Patterson-Kane JC 《American journal of veterinary research》2005,66(4):564-568
OBJECTIVE: To determine whether specific treadmill exercise regimens would accelerate age-related changes in collagen fibril diameter distributions in the common digital extensor tendon (CDET) of the forelimbs of young Thoroughbreds. ANIMALS: 24 female Thoroughbreds. PROCEDURE: Horses were trained for 18 weeks (6 horses; short term) or 18 months (5 horses; long term) on a high-speed treadmill; 2 age-matched control groups (6 horses/group) performed walking exercise only. Horses were (mean +/- SD) 24 +/- 1 months and 39 +/- 1 months old at termination of the short-term and long-term regimens, respectively. Midmetacarpal CDET specimens were obtained and processed for transmission electron microscopy. Diameter and area of at least 1,000 collagen fibrils/specimen were measured by use of computerized image analysis. Mass-average diameter (MAD) of collagen fibrils and collagen fibril index were calculated for each horse. RESULTS: Collagen fibril MAD for the older horses was significantly less than that for the younger horses. Exercise did not significantly affect fibril diameter or distributions in either age group, and collagen fibril index did not differ significantly between groups. CONCLUSIONS AND CLINICAL RELEVANCE: Age-related reduction in collagen fibril MAD agreed with findings for other tendons and species. Training did not accelerate age-related change in the CDET in contrast to a reported decrease in collagen fibril MAD in the superficial digital flexor tendon of horses trained long term. Our results support the concept that the functionally distinct nature of the CDET and superficial digital flexor tendon in horses results in fundamentally different responses to high-speed exercise regimens. 相似文献
45.
Senior Care Guidelines Task Force AAHA Epstein M Kuehn NF Landsberg G Lascelles BD Marks SL Schaedler JM Tuzio H 《Journal of the American Animal Hospital Association》2005,41(2):81-91
This paper provides a working framework for enhancing the well-being of senior pet dogs and cats. Approaches to screening the medical status of senior pets are described in detail, with particular emphasis on establishing baseline data in healthy animals, the testing of clinically ill animals, and assessing senior pets prior to anesthesia and surgery. The management of pain and distress and the application of hospice and palliative care are addressed. Advice on ways to approach euthanasia and dealing with end-of-life issues is also provided. 相似文献
46.
47.
48.
Mueller RS Krebs I Power HT Fieseler KV 《Journal of the American Animal Hospital Association》2006,42(3):189-196
A retrospective study of 91 dogs with pemphigus foliaceus was performed. Clinical signs of the disease included crusts (n=79), pustules (n=36), and alopecia (n=33). Lesions were most common on the trunk (n=53), inner pinnae (n=46), face (n=37), and foot pads (n=32). Cytological evaluation revealed acantholytic keratinocytes in 37 of 48 dogs. Results of combination treatment with prednisolone and azathioprine were comparable to results with prednisolone therapy alone. More than half of the dogs achieved remission with appropriate therapy, and another 25% significantly improved. 相似文献
49.
Koukoulitsa C Karioti A Bergonzi MC Pescitelli G Di Bari L Skaltsa H 《Journal of agricultural and food chemistry》2006,54(15):5388-5392
From the polar extracts of Origanum vulgare L. ssp. hirtum 19 compounds have been isolated. The structures and relative stereochemistry have been elucidated by spectroscopic analysis and determined as apigenin, luteolin, chrysoeriol, diosmetin, quercetin, eriodictyol, cosmoside, vicenin-2, caffeic acid, p-menth-3-ene-1,2-diol 1-O-beta-glucopyranoside, thymoquinol 2-O-beta-glucopyranoside, thymoquinol 5-O-beta-glucopyranoside, thymoquinol 2,5-O-beta-diglucopyranoside, 12-hydroxyjasmonic acid, 12-hydroxyjasmonic acid 12-O-beta-glucopyranoside, lithospermic acid B, rosmarinic acid, 10-epi-lithospermic acid, and epi-lithospermic acid B. The three latter products display unusual stereochemistry of the 3,4-hydroxyphenyllactic acid unit(s), which to the authors' best knowledge has never been reported before in similar compounds. Moreover, lithospermic acid B (and its stereoisomers), p-menth-3-ene-1,2-diol 1-O-beta-glucopyranoside, 12-hydroxyjasmonic acid, and 12-hydroxyjasmonic acid 12-O-beta-glucopyranoside were isolated for the first time from Origanum species. 相似文献
50.