全文获取类型
收费全文 | 464篇 |
免费 | 29篇 |
专业分类
林业 | 8篇 |
农学 | 22篇 |
基础科学 | 3篇 |
56篇 | |
综合类 | 49篇 |
农作物 | 22篇 |
水产渔业 | 35篇 |
畜牧兽医 | 265篇 |
园艺 | 2篇 |
植物保护 | 31篇 |
出版年
2023年 | 5篇 |
2020年 | 12篇 |
2019年 | 12篇 |
2018年 | 10篇 |
2017年 | 5篇 |
2016年 | 16篇 |
2015年 | 6篇 |
2014年 | 9篇 |
2013年 | 25篇 |
2012年 | 11篇 |
2011年 | 23篇 |
2009年 | 10篇 |
2008年 | 22篇 |
2007年 | 21篇 |
2006年 | 15篇 |
2005年 | 19篇 |
2004年 | 15篇 |
2003年 | 15篇 |
2002年 | 13篇 |
2001年 | 15篇 |
2000年 | 11篇 |
1999年 | 14篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 12篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 8篇 |
1985年 | 7篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 7篇 |
1975年 | 8篇 |
1974年 | 6篇 |
1973年 | 10篇 |
1972年 | 7篇 |
1971年 | 6篇 |
1970年 | 8篇 |
1969年 | 7篇 |
1968年 | 4篇 |
1967年 | 5篇 |
排序方式: 共有493条查询结果,搜索用时 187 毫秒
21.
Catherine Elizabeth Gibson David Williams Rebecca Dunlop Suzanne Beck 《水产资源保护:海洋与淡水生态系统》2020,30(8):1702-1710
- Bottlenose dolphins encountered around the Irish coast are considered part of a wide‐ranging coastal community; however, knowledge on the significance of the north of Ireland for this species is limited by a lack of dedicated effort.
- Through social media, the opportunity now exists to gather large volumes of citizen science data in the form of high‐quality images, potentially extending the spatial and temporal scope of photo‐identification studies.
- The purpose of this study was to investigate social media as a data resource for photo‐identification studies and to provide a preliminary assessment of bottlenose dolphins in the north of Ireland. Specifically, the study sought to examine the photo‐identification data for spatial clustering.
- The study identified 54 well‐marked individuals and provided evidence of potential year‐round occurrence, with successful re‐sightings throughout the study period (2007–2016). There was a geographic concentration of re‐sightings along the north of Ireland, suggestive of interannual site fidelity. These results provide scientific rationale for strategically targeting the north of Ireland in future research on the Irish coastal community.
- For effective conservation of the bottlenose dolphin it is imperative that scientific research, and resultant management objectives, consider wide‐ranging communities such as the Irish coastal community. Our research highlights data collection via social media as a cost‐effective and scientifically valuable tool in the photo‐identification of coastal cetaceans. We recommend that this method is used in research on low‐density and wide‐ranging coastal cetaceans.
22.
I. Gibson Gaylord Delbert M. Gatlin III 《Journal of the World Aquaculture Society》2000,31(3):326-336
A feeding trial was undertaken to evaluate compensatory growth in channel catfish and to chronicle the changes in body condition associated with the imposed feeding strategy. Four 1200-L circular tanks were each stocked with approximately 600 fingerling channel catfish (mean initial weight 32 g). Two tanks represented control fish which were fed to apparent satiation once daily throughout the trial. The two remaining tanks of fish were unfed for 4 wk and subsequently refed daily to apparent satiation for the following 10 wk in order to elicit a compensatory growth response. Fish fed to apparent satiation during the first 4 wk of the trial had a 41% increase in body weight, while the fasted fish decreased in weight by 20%. During the subsequent refeeding period, previously unfed fish were not able to increase growth rates sufficiently to overcome weight loss imposed by the 4-wk feed restriction. However, after 8 wk of refeeding, total increase in body weight of the previously unfed fish was 179 % of initial weight and similar to that of control fish which gained 231 % of initial weight. Hepatosomatic index (HSI) and condition factor decreased rapidly during the fasting period and increased rapidly to control levels during subsequent refeeding. The intraperitoneal fat (1PF) ratio and muscle ratio responded more slowly to feed restriction with IPF ratio decreasing consistently after 2 wk feed restriction. Muscle ratio showed little effect from the 4-wk period of feed deprivation. It appears that not feeding channel catfish fingerlings for 4 wk is too long to induce a compensatory growth response that is optimal for aquaculture; however, HSI may be the index of choice for detecting when refeeding should begin to maximize compensatory growth. 相似文献
23.
S V Gibson A A Rottinghaus J E Wagner H F Srills P L Stogsdill D A Kinden 《American journal of veterinary research》1990,51(1):143-147
Intranuclear inclusions indicative of adenovirus infection were detected microscopically in formalin-fixed intestinal tissues from preweanling Syrian hamsters. The amphophilic intranuclear inclusion bodies were observed in ileal enterocytes from 16-to 24-day-old hamsters. Electron microscopy revealed large numbers of 72 +/- 3-nm viral particles typical of adenoviridae in enterocytic nuclei. Serum antibodies reacted with mouse adenovirus strains K87 and, to a lesser extent, FL, by indirect fluorescent antibody testing. Clinical disease was not associated with the adenoviral infections. Hamsters from 10 production colonies, including all major commercial Syrian hamster suppliers in the United States, were surveyed and all had serologic or histopathologic evidence of adenovirus infection. 相似文献
24.
J R Vega C A Gibson T C Skaar D L Hadsell C R Baumrucker 《Journal of animal science》1991,69(6):2538-2547
Concentrations of IGF-I and IGF-II, and IGF binding proteins (IGFBP) in serum and mammary gland secretions were surveyed during the dry period and early lactation of 30 Holstein cows. Although there was a threefold drop in the concentration of IGF-I in serum from the last week of the dry period to parturition (81 +/- 7 to 24 +/- 3 ng/ml, P less than .01), there was no significant change in serum IGF-II concentration during this period (150 +/- 17 vs 173 +/- 13 ng/ml, P greater than .05). Furthermore, a 57% increase in serum IGF-I was observed from the last week of lactation to the second week of drying off (100 +/- 5 to 157 +/- 8 ng/ml, P less than .05). Changes in serum IGF-II were not observed (126 +/- 11 vs 150 +/- 10 ng/ml, respectively; P greater than .05). Although IGF-I, IGF-II, and IGFBP concentrations in mammary secretions peaked 2 wk before parturition (2.95 +/- 1.1, 1.83 +/- .6, and 7.27 +/- .76 micrograms/ml, respectively), total output/quarter was highest in colostrum (394 +/- 119, 295 +/- 132, and 2,680 +/- 1,967 micrograms/quarter, respectively). Weekly milking of two individual quarters during the dry period did not affect (P greater than .05) IGF-I or IGF-II concentration (ng/ml) or total output (microgram/quarter) and milk yield in colostrum and milk (2 wk and 7 wk) compared with the ipsilateral quarter. The data support the hypothesis that IGF-I may be transported by the mammary gland epithelium. Furthermore, the secretion mechanisms of IGF-I, IGF-II, and IGFBP by the gland may be related to each other. 相似文献
25.
K L Gibson R T vanEe R D Pechman 《Journal of the American Veterinary Medical Association》1991,198(5):886-890
Complications associated with femoral capital physeal (CP) fractures in 34 dogs were evaluated. Fractures were surgically repaired, using divergent K-wires or lag screws; radiographic follow-up was available for 21 CP fractures. In all cases, radiographic abnormalities such as degenerative joint disease and resorption of the femoral neck and/or head were seen. Changes were more severe when fracture occurred at an early age. For 4 of 21 dogs (20%), femoral head and neck excision was performed because of complications associated with CP fracture repair. Prognosis for femoral CP fractures is guarded, although affected dogs should be able to function as pets. 相似文献
26.
Guy R. Alexander BVSc Cert VR Katherine T. Gibson BVSc MS Diplomate ACVS Robert E. Day MBiomedEng BEng CPEng Ian D. Robertson BVSc PhD MACVSc 《Veterinary surgery : VS》2001,30(6):522-527
OBJECTIVE: To measure the effects of transection of the accessory ligament of the superficial digital flexor (SDF) muscle (superior check desmotomy) on flexor tendon and suspensory ligament (SL) strain in vitro. STUDY DESIGN: In vitro experimental biomechanical investigation. ANIMALS USED: Ten equine cadaver forelimbs. METHODS: The effects of superior check desmotomy were determined using equine cadaver forelimbs secured in a servocontrolled hydraulic testing machine. Strain sensors were used to measure strain on the superficial and deep digital flexor tendons and SL, and a goniometer was used to measure joint angles when the limb was loaded at 890 N and 3,115 N before desmotomy, and at 3,115 N after desmotomy. RESULTS: Superior check desmotomy was associated with significantly increased strains on the SDF tendon and SL, and significant alterations in the angles of the metacarpophalangeal and carpal joints. CONCLUSIONS: The superior check ligament has an important role in maintaining joint angles and load distribution in the forelimb. Lengthening of the SDF musculotendinous unit after superior check desmotomy may be associated with increased strain on the SL. CLINICAL RELEVANCE: Transection of the accessory ligament of the SDF muscle may predispose horses to SL desmitis postoperatively. 相似文献
27.
28.
29.
30.
Abscisic acid (10?4M) applied via absorbent discs bound to the stems of 6 wk oldE. camaldulensis seedlings caused changes in leaf shape and orientation similar to those induced by nutritional and water stress. Seedlings from the driest provenance, Tennant Creek, were more responsive to ABA than seedlings from the wettest provenance, Katherine, and the response of Petford seedlings was intermediate. Likewise, Tennant Creek seedlings were most, and Katherine seedlings least, responsive to water and/or nutritional stress. Seedlings that responded to the application of ABA produced prematurely strengthened, linear leaves with the lamina rotated from horizontal to vertical. The ability of Tennant Creek seedlings to readily assume this form may be a specific adaptation for the particularly difficult conditions in their natural environment. 相似文献