全文获取类型
收费全文 | 2424篇 |
免费 | 155篇 |
专业分类
林业 | 58篇 |
农学 | 51篇 |
基础科学 | 12篇 |
221篇 | |
综合类 | 444篇 |
农作物 | 98篇 |
水产渔业 | 149篇 |
畜牧兽医 | 1372篇 |
园艺 | 51篇 |
植物保护 | 123篇 |
出版年
2022年 | 18篇 |
2021年 | 20篇 |
2020年 | 31篇 |
2019年 | 35篇 |
2018年 | 36篇 |
2017年 | 31篇 |
2016年 | 36篇 |
2015年 | 25篇 |
2014年 | 43篇 |
2013年 | 119篇 |
2012年 | 78篇 |
2011年 | 87篇 |
2010年 | 56篇 |
2009年 | 49篇 |
2008年 | 74篇 |
2007年 | 87篇 |
2006年 | 83篇 |
2005年 | 78篇 |
2004年 | 82篇 |
2003年 | 74篇 |
2002年 | 77篇 |
2001年 | 74篇 |
2000年 | 69篇 |
1999年 | 58篇 |
1998年 | 31篇 |
1997年 | 21篇 |
1996年 | 29篇 |
1993年 | 23篇 |
1992年 | 40篇 |
1991年 | 68篇 |
1990年 | 46篇 |
1989年 | 45篇 |
1988年 | 42篇 |
1987年 | 32篇 |
1986年 | 59篇 |
1985年 | 53篇 |
1984年 | 32篇 |
1983年 | 28篇 |
1980年 | 28篇 |
1979年 | 32篇 |
1978年 | 32篇 |
1975年 | 21篇 |
1974年 | 29篇 |
1973年 | 27篇 |
1972年 | 36篇 |
1971年 | 37篇 |
1970年 | 29篇 |
1969年 | 17篇 |
1967年 | 23篇 |
1966年 | 17篇 |
排序方式: 共有2579条查询结果,搜索用时 15 毫秒
61.
62.
63.
PR WIDDERS KJ COATES S. WARNER JC BEATTIE IR MORGAN MW HICKEY† 《Australian veterinary journal》1995,72(6):208-211
SUMMARY The microbiological quality of carcases, meat and environmental surfaces was evaluated in commercial boning rooms processing beef and lamb. There was considerable variation in the level of microbial contamination on both carcases and meat, with counts ranging from less than 20 to 108/cm2 on carcases and to 2 times 107/cm2 on meat. The level of microbial contamination on meat was influenced by the level of carcase contamination at boning and by the boning process itself. Carcase contamination was the major determinant of microbiological quality, as more than 70% of carcases had microbial counts greater than 103/cm2. Cutting boards were a major source for microbial dissemination during boning, particularly when carcase counts were less than 103/cm2. If carcases were heavily contaminated, the contamination of processing surfaces was irrelevant in determining microbial loads on meat. Where carcase contamination was at low to moderate levels, the contribution of the boning process to the contamination on meat assumed increased significance. Under these conditions, improved sanitation of cutting surfaces in the boning room resulted in a significant reduction in microbial contamination on the surface of meat. These results can form the basis for ensuring that improvements made in carcase management before boning, to improve microbiological quality, will be preserved through attention to cutting board hygiene during boning. 相似文献
64.
Variance components were estimated from field-collected performance records for use in national beef sire evaluation mixed-model programs. Estimates of residual error variances (sigma 2e), sire effect variances (sigma 2s) and dam effect variances (sigma 2d) were obtained for the American Hereford and the American Angus breeds for each of three growth traits: birth weight, weaning weight and postweaning gain. Estimates obtained for birth weight were sigma 2e, 8.43 and 9.26 kg2; sigma 2s, 1.34 and .66 kg2; and sigma 2d, 3.24 and 3.70 kg2 for the Hereford and Angus breeds, respectively. Estimates obtained for weaning weight were sigma 2e, 438.09 and 267.38 kg2; sigma 2s, 20.37 and 17.13 kg2; and sigma 2d, 162.25 and 157.28 kg2 for the Hereford and Angus breeds, respectively. Estimates obtained for postweaning gain were sigma 2e, 425.75 and 374.33 kg2; sigma 2s, 20.08 and 16.49 kg2; and sigma 2d, 41.74 and 48.61 kg2 for the Hereford and Angus breeds, respectively. 相似文献
65.
66.
67.
Differentiation between dogs with thrombosis and normal dogs using the overall hemostasis potential assay 下载免费PDF全文
Anna L. Dengate BVSc BMedSc Marie‐Christine Morel‐Kopp PhD Julia A. Beatty PhD BVetMed BSc Vanessa Barrs BVSc MVetClinStud Jody A. Braddock BVSc MVetClinStud Richard K. Churcher BVSc Bethany J. Wilson BVSc PhD Christopher M. Ward BMedSc MBChB PhD 《Journal of Veterinary Emergency and Critical Care》2016,26(3):446-452
68.
Alex Bukoski PhD DVM Matthew Winter DVM DACVR Carsten Bandt DVM DACVECC Mary Wilson RT CV MR CT Andre Shih DVM DACVA 《Journal of Veterinary Emergency and Critical Care》2010,20(4):393-397
Objective – To compare the placement feasibility and amount of bone trauma induced by 3 intraosseous (IO) access techniques in cats: an automatic impact penetration device (A), an automatic rotary insertion device (B), and a manual IO needle (C). Design – Prospective ex vivo study. Setting – University. Animals – Eighteen adult mixed breed feline cadavers. Interventions – Cadavers provided 72 total IO insertion locations divided equally between the right and left humerus and tibia. The 3 IO techniques were randomly allocated to these locations. Time to successful insertion, ease of insertion, and success rate were recorded. Each insertion site was analyzed for the number of bone fragments and defect diameter by computed tomography. Measurements and Main Results – Device B had lower time of insertion (P=0.01) compared with devices A and C. Device B had better ease of insertion scores (P<0.01) compared with devices A and C. No differences were detected between insertion sites (tibia versus humerus). No differences in the number of bone fragments, defect diameter, or success rate were detected among devices (P=0.06, 0.31, and 0.14, respectively). Conclusions – All 3 IO access methods evaluated yield acceptable results. Device B is significantly faster and easier to place in cat cadavers when compared with other methods. 相似文献
69.
Andrea M. DeLuke Dave A. Allen Eric R. Wilson Jayce A. Lineberger Terry W. Lehenbauer Michelle Fabiani Brian A. Poteet 《The Canadian veterinary journal. La revue veterinaire canadienne》2012,53(10):1095-1099
Radiographic osteoarthritis scores were determined in 60 dogs up to 3 years following tibial plateau leveling osteotomy. Radiographs taken immediately following surgery and at long-term follow-up 1 to 3 years later were evaluated by 2 certified radiologists using a modified 32-point osteoarthritis scale. Changes in osteoarthritis scores were evaluated by paired t-tests and regression analysis. Sub-groups of dogs were formed to evaluate if osteoarthritis scores changed differently for follow-up periods of < 24 months compared with those > 24 months. There was a significant increase in osteoarthritis score from post-operative to follow-up evaluations for all dogs studied. Regression analysis of the relationship of months after surgery to change in osteoarthritis score was not significant. These results indicate that osteoarthritis did progress following tibial plateau leveling osteotomy, but not in a linear fashion over time. 相似文献
70.
Five New World camelids were admitted to the Western College of Veterinary Medicine between 1996 and 2003 for evaluation of femoral fractures. There were three alpacas and two llamas. Four of the animals were female and three were less than 3 months of age. Fracture configurations consisted of distal physeal fractures (three), a comminuted diaphyseal/metaphyseal fracture, and a transverse diaphyseal fracture. Fractures were diagnosed with a combination of physical examination and radiographs in all cases. All five fractures were repaired with internal fixation and three animals were discharged from the hospital with fractures that healed. One cria underwent successful internal fixation but died from pulmonary oedema during recovery from anaesthesia. Postoperative complications were rare and limited to inadequate fracture stability in one alpaca and prolonged recovery to weight bearing in another. One llama with a comminuted metaphyseal fracture, repaired with a 4.5 mm dynamic compression plate, subsequently had catastrophic failure of the bone 17 days after surgery. Overall the clients were pleased with the outcome of discharged animals. Although femoral fractures are considered rare, they pose a unique opportunity for the large animal veterinarian to successfully achieve fracture union with the aid of internal fixation. 相似文献