全文获取类型
收费全文 | 188篇 |
免费 | 27篇 |
专业分类
林业 | 2篇 |
17篇 | |
综合类 | 39篇 |
水产渔业 | 1篇 |
畜牧兽医 | 153篇 |
园艺 | 1篇 |
植物保护 | 2篇 |
出版年
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 3篇 |
2016年 | 11篇 |
2015年 | 8篇 |
2014年 | 5篇 |
2013年 | 9篇 |
2012年 | 9篇 |
2011年 | 9篇 |
2010年 | 9篇 |
2009年 | 10篇 |
2008年 | 8篇 |
2007年 | 5篇 |
2006年 | 6篇 |
2005年 | 8篇 |
2004年 | 3篇 |
2003年 | 4篇 |
2002年 | 2篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 9篇 |
1997年 | 11篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 6篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 8篇 |
1988年 | 3篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1905年 | 1篇 |
1898年 | 1篇 |
1894年 | 2篇 |
1893年 | 1篇 |
1892年 | 2篇 |
1891年 | 1篇 |
1890年 | 1篇 |
1888年 | 4篇 |
1887年 | 1篇 |
1885年 | 2篇 |
排序方式: 共有215条查询结果,搜索用时 15 毫秒
71.
72.
Diane Frank Suzanne Lecomte Guy Beauchamp 《The Canadian veterinary journal. La revue veterinaire canadienne》2021,62(5):491
Peer-reviewed scientific publications on the topic of dog bites are numerous. Montreal was one of the first municipalities in the province of Quebec to require mandatory assessment of aggressive dogs by veterinarians. In 2019, dogs reported as aggressive and considered a potential risk to public safety by city officials were scheduled for a mandatory behavioral assessment by a veterinarian. For the purpose of this study, only aggressive dogs that had bitten (N = 65) were included. The goals were to better describe the aggressive behavior of these dogs (behavioral sequence, type of aggression, and overall reactivity) and perhaps identify new possible risk factors related to severity of injury and dangerousness. The number of signs of increased arousal/reactivity was positively and significantly associated with the injury severity score. Dangerousness increased with size of dogs. Entire males were most dangerous despite absence of recognizable differences in body weight between neutered and unneutered males. 相似文献
73.
Summary The spatial variability of denitrification in soil was studied further by comparing dry-sieved and wetsieved aggregates of different sizes. It was observed that the denitrification rate generally decreased as the drysieved aggregate size increased. In contrast, the denitrification rate increased as the wet-sieved aggregate size increased. In both cases, however, the denitrification rate was positively related to aerobically mineralizable C. Oven-warming of the wet-sieved aggregates at 105°C for 30 min increased the denitrification rate, apparently due to the release of C substrate. Nevertheless, the positive relationship between the denitrification rate and the wetsieved aggregate size persisted. There was no clear relationship between water-soluble C and the denitrification rate. There may have been a contribution from C in microbial polysaccharides in aggregates of different sizes. The results demonstrated that there was a large spatial variability in denitrification over short distances in soil, which was associated with aggregates of different sizes and water stability. 相似文献
74.
The removal of conifers planted during the twentieth century on sites that had been woodland for many centuries, with the intention of restoring native broadleaved species, is an important aim of forestry policy in Great Britain. Current guidance generally advocates gradual removal of plantation trees using continuous cover silviculture and restocking by natural regeneration, but methods are largely untested. This study investigated natural regeneration of trees and shrubs at sites where western hemlock had been established either pure or in mixture with native broadleaved species. Western hemlock had been cleared from 70% of the sites. There were c. 10?C300 stems ha?1 providing canopy cover of 10?C90%; the predominant broadleaved canopy trees were ash, beech, birch and oak. The ground flora of all sites was species poor; bramble was the predominant vegetation type overall, but grasses, rushes and shrubs were relatively more abundant on open sites. A total of 15 native tree species were regenerating, birch was most common and at most sites there were few valuable broadleaved timber species. Although combined numbers of seedlings and saplings varied from 200 to 20,000 ha?1, large areas of most sites had few regenerating trees and <10% of their area was becoming restocked with timber species. Relationships between seedling numbers and site characteristics were complex and varied with species, but there was a consistent positive relationship between the presence of nearby parent trees and the frequency and abundance of seedlings. The results indicate that the current reliance on natural regeneration may be unwise especially for those broadleaved species such as oak and beech which are valued for their timber. 相似文献
75.
76.
JL O'RIELLY 《Australian veterinary journal》1993,70(12):442-444
SUMMARY: The IgG concentration of plasma from 13 mares was measured by radial immunodiffusion when fresh and after storage at -4°C and thawing by 3 methods. There was no significant (P > 0.05) reduction in the IgG concentration when plasma was thawed over 6 hours at 22°C (1352.9 ± 101.6 mg/dL) (mean ± SEM) compared with the fresh sample (1369.5 ± 88.1 mg/dL). In contrast, there was a significant (P < 0.05) reduction in the IgG concentration of plasma that was rapidly thawed at 57°C over 50 minutes (1142.9 ±66.2 mg/dL), or placed in a microwave oven for 20 to 25 minutes (1093.4 ± 74.4 mg/dL). When plasma is administered to hypo-gammaglobulinaemic newborn foals, a larger volume is required when thawing is rapid than when thawing is slow or when fresh plasma is administered. 相似文献
77.
Fradette ME Céleste C Richard H Beauchamp G Laverty S 《American journal of veterinary research》2007,68(2):128-133
OBJECTIVE: To evaluate the effects of continuous oral administration of phenylbutazone on serum and synovial fluid biomarkers of skeletal matrix metabolism in horses. ANIMALS: 11 adult female horses without clinical or radiographic evidence of joint disease. PROCEDURES: Horses were randomly assigned to control or treatment groups. Phenylbutazone was administered orally twice daily at a dose of 4.4 mg/kg for 3 days to the treatment group and subsequently at a dose of 2.2 mg/kg for 7 days. Serum and radiocarpal synovial fluid samples were obtained at baseline and thereafter at regular intervals for 4 weeks. Biomarkers of cartilage aggrecan synthesis (chondroitin sulfate 846) and type II collagen synthesis (procollagen type II C-propeptide) and degradation (collagen type II cleavage) were assayed. Biomarkers of bone synthesis (osteocalcin) and resorption (C-terminal telopeptide of type I collagen) were also measured. RESULTS: No significant differences were found between control and treatment groups or temporally for the biomarkers chondroitin sulfate 846, procollagen type II C-propeptide, collagen type II cleavage, and C-terminal telopeptide of type I collagen in serum or synovial fluid. A significant increase in osteocalcin concentration occurred in synovial fluid during treatment in the treated group. No treatment effect was detected for serum osteocalcin concentration. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that continuous phenylbutazone administration at recommended doses altered some biomarkers in healthy equine joints after short periods of administration. Increased osteocalcin concentration may indicate an undetermined anabolic effect of phenylbutazone administration on periarticular bone or transient induction of osteogenesis in articular chondrocytes or a mesenchymal subpopulation of synoviocytes. 相似文献
78.
79.
Subpolar North Atlantic proxy records document millennial-scale climate variations 500,000 to 340,000 years ago. The cycles have an approximately constant pacing that is similar to that documented for the last glacial cycle. These findings suggest that such climate variations are inherent to the late Pleistocene, regardless of glacial state. Sea surface temperature during the warm peak of Marine Isotope Stage 11 (MIS 11) varied by 0.5 degrees to 1 degrees C, less than the 4 degrees to 4.5 degrees C estimated during times of ice growth and the 3 degrees C estimated for glacial maxima. Coherent deep ocean circulation changes were associated with glacial oscillations in sea surface temperature. 相似文献
80.
Magnetic Field and Plasma Observations at Mars: Initial Results of the Mars Global Surveyor Mission 总被引:2,自引:0,他引:2
MH Acu?a JEP Connerney P Wasilewski RP Lin KA Anderson CW Carlson J McFadden DW Curtis D Mitchell H Reme C Mazelle JA Sauvaud C d'Uston A Cros JL Medale SJ Bauer P Cloutier M Mayhew D Winterhalter NF Ness 《Science (New York, N.Y.)》1998,279(5357):1676-1680
The magnetometer and electron reflectometer investigation (MAG/ER) on the Mars Global Surveyor spacecraft has obtained magnetic field and plasma observations throughout the near-Mars environment, from beyond the influence of Mars to just above the surface (at an altitude of approximately 100 kilometers). The solar wind interaction with Mars is in many ways similar to that at Venus and at an active comet, that is, primarily an ionospheric-atmospheric interaction. No significant planetary magnetic field of global scale has been detected to date (<2 x 10(21) Gauss-cubic centimeter), but here the discovery of multiple magnetic anomalies of small spatial scale in the crust of Mars is reported. 相似文献