全文获取类型
收费全文 | 492篇 |
免费 | 65篇 |
国内免费 | 3篇 |
专业分类
林业 | 34篇 |
农学 | 11篇 |
基础科学 | 6篇 |
68篇 | |
综合类 | 79篇 |
农作物 | 21篇 |
水产渔业 | 12篇 |
畜牧兽医 | 316篇 |
园艺 | 1篇 |
植物保护 | 12篇 |
出版年
2020年 | 5篇 |
2018年 | 5篇 |
2017年 | 12篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 10篇 |
2013年 | 32篇 |
2012年 | 17篇 |
2011年 | 22篇 |
2010年 | 11篇 |
2009年 | 18篇 |
2008年 | 15篇 |
2007年 | 18篇 |
2006年 | 24篇 |
2005年 | 10篇 |
2004年 | 15篇 |
2003年 | 16篇 |
2002年 | 14篇 |
2001年 | 15篇 |
2000年 | 17篇 |
1999年 | 13篇 |
1998年 | 12篇 |
1997年 | 9篇 |
1996年 | 11篇 |
1995年 | 4篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 5篇 |
1991年 | 8篇 |
1990年 | 8篇 |
1989年 | 11篇 |
1988年 | 15篇 |
1987年 | 5篇 |
1986年 | 7篇 |
1985年 | 12篇 |
1984年 | 8篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 8篇 |
1980年 | 4篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1976年 | 6篇 |
1975年 | 6篇 |
1974年 | 8篇 |
1973年 | 8篇 |
1972年 | 4篇 |
1970年 | 6篇 |
1967年 | 7篇 |
1963年 | 3篇 |
排序方式: 共有560条查询结果,搜索用时 15 毫秒
101.
Faleiros RR Johnson PJ Nuovo GJ Messer NT Black SJ Belknap JK 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2011,25(1):107-115
Background: While there is evidence of laminar leukocyte infiltration in black walnut extract (BWE)‐induced laminitis, there is no such evidence for carbohydrate overload (CHO) laminitis. Objective: To assess presence of leukocytes and signs of epidermal stress/injury in the laminar tissue from horses with CHO‐induced laminitis. Animals: Twenty‐four adult horses. Methods: Immunohistochemistry for myeloid cell markers calprotectin (CP) and monocyte‐specific marker (CD163) was performed on laminar sections obtained from 2 groups of horses in the CHO model: the developmental time point (DTP) group (n = 6) and the onset of lameness (LAM) group (n = 6), and a control (CON) group (n = 8). Results: DTP was characterized by an increase in CP+ leukocytes (7.8‐fold increase versus CON, P < .001), and LAM time point was characterized by a more marked increase in laminar CP+ (108.5‐fold, P < .001) and mild increase in CD163+ (1.9‐fold, P= .007) cell counts. Increased CP epidermal signal (indicating epidermal stress or injury) occurred consistently at the LAM time point, although histological evidence of basement membrane (BM) detachment was minor, only being present in 3/6 horses. Conclusions and Clinical Relevance: Maximal laminar leukocyte infiltration and epithelial stress occurred at the onset of lameness in the CHO model showing a different temporal pattern from the BWE model, where maximal leukocyte infiltration clearly precedes epithelial stress. Leukocyte infiltration before major histological changes in the CHO model indicates that leukocyte infiltration can be a cause of and not a reaction to BM degradation and structural failure. 相似文献
102.
Faleiros RR Leise BS Watts M Johnson PJ Black SJ Belknap JK 《Veterinary immunology and immunopathology》2011,144(1-2):45-51
Chemokines play a vital role in leukocyte activation and emigration that reportedly plays a central role in laminar injury in equine laminitis. The purpose of this study was to evaluate the pattern of laminar chemokine expression in horses in the classical carbohydrate overload (CHO)-model of laminitis. Laminar samples were obtained 24h following water administration in the control group (CON, n=8), and at the onset of fever (≥ 102°F, 12-22 h post CHO, DEV group, n=8) and at the onset of lameness (20-48 h post CHO, LAM group, n=8) in induced horses. Real time quantitative PCR was performed on all samples in order to determine laminar mRNA concentrations of both CXC chemokines (CXCL1, CXCL6, CXCL8) and CC chemokines (CCL2 [MCP-1], CCL3 [MIP-1α], and CCL8 [MCP-2]). Data were subjected to ANOVA followed by Student-Newman-Keuls (P<0.05). Laminar mRNA concentrations for all CXC chemokines were increased (P<0.05) at both the DEV and LAM horses when compared to the control horses, whereas mRNA concentrations of CCL2 and CCL8 were only increased in the LAM horses when compared to controls and the DEV horses. When taken in context with our previous studies, CXCL1, CXCL6 and CXCL8 increases precede peak laminar leukocyte accumulation. Additionally, CCL2 and CCL8 expression corroborate previous reports of monocyte/macrophage accumulation in affected laminae. Compared with previous studies, our findings demonstrate that increased laminar CXC chemokine expression consistently precedes peak leukocyte accumulation and onset of lameness in CHO laminitis models. Chemokine antagonists may be considered as possible therapeutic targets to decrease the influx of leukocytes that occurs during the development of equine laminitis. 相似文献
103.
Leise BS Faleiros RR Watts M Johnson PJ Black SJ Belknap JK 《Equine veterinary journal》2011,43(1):54-61
Reasons for performing study: There is a need to assess the laminar inflammatory response in a laminitis model that more closely resembles clinical cases of sepsis‐related laminitis than the black walnut extract (BWE) model. Objectives: To determine if a similar pattern of laminar inflammation, characterised by proinflammatory cytokine expression, occurs in the CHO model of laminitis as has been previously reported for the BWE model. Methods: Sixteen horses administered 17.6 g of starch (85% corn starch/15% wood flour)/kg bwt via nasogastric (NG) tube were anaesthetised either after developing a temperature >38.9°C (DEV group, n = 8) or at onset of Obel grade 1 lameness (OG1 group, n = 8). Control horses (CON group, n = 8) were anaesthetised 24 h after NG administration of 6 l of deionised water. Laminar tissue was collected from horses while under anaesthesia, followed by humane euthanasia. Real time‐quantitative PCR was used to assess laminar mRNA concentrations of genes involved in inflammatory signalling. Results: Increased mRNA concentrations (P<0.05) for IL‐1β, IL‐6, IL‐12p35, COX‐2, E‐selectin and ICAM‐1 were present in laminae from horses with OG1 lameness but not at the DEV time, when compared to the CON horses. No differences between the groups were found for IL‐2, IL‐4, IL‐10, TNF‐α, IFN‐γ or COX‐1 at either the DEV or OG1 time points. Conclusions: There was a notable difference in the temporal pattern of inflammatory events between the BWE and CHO models, with the majority of laminar inflammatory events appearing to occur at or near the onset of lameness in the CHO model, whereas many of these events peak earlier in the developmental stages in the BWE model. This suggests that, in addition to circulating inflammatory molecules, there may be a local phenomenon in the CHO model resulting in the simultaneous onset of multiple laminar events including endothelial activation, leucocyte emigration and proinflammatory cytokine expression. Potential relevance: The similar (although somewhat delayed) inflammatory response in the CHO model of laminitis indicates that inflammatory signalling is a consistent entity in the pathophysiology of laminitis. 相似文献
104.
In two experiments the growth of clover undersown to wheat was linearly related to the amount of light available. There were strong indications that clover growth and light within N.-S. rows were superior to those within E.-W. rows of wheat, and within N.-S. rows, those along the middle position were superior to others. The large difference between the growth of clover sown alone and with wheat indicated that beneath wheat the clover suffered from competition for other factors, probably soil moisture, which was even greater than that for light. Beneath wheat at the reduced level of growth there was a positive linear relationship between yield of clover and available light. 相似文献
105.
The distribution of leaf area and light intensity within wheat crops differing in row direction, row spacing and rate of sowing is described. Regardless of the manner of planting, 75% of the total leaf area was found within a band 31/2 in. wide, centred on the centre of the row. Light penetration within crops spaced at 14 in. was greater than within those spaced at 7 in. Light penetration within rows running N.–S. was more uniform and higher, particularly around noon, than within rows running E.-W. Within N.-S. rows the position midway between rows received the highest amount of light, but light decreased on either side until it was least beneath the rows. Within E.-W. rows at 14 in. spacing, maximum light was recorded at 101/2 in. on the southern side of a row, decreasing progressively as the row was approached. 相似文献
106.
107.
108.
109.
110.
M Briggs M Schmidt D Black R Roach J Opdahl G Stark D Owens M Driver 《Journal of the American Veterinary Medical Association》1988,192(10):1455-1456
An 18-year-old African elephant was determined to have a nonrepairable crack in its left tusk. Treatment included extraction of the tusk, using rotational and extractional forces, and administration of antibiotics, followed by 1 year of flushing the opened tusk cavity with warm tap water. Two years after surgery, the elephant was healthy, and the tusk cavity was 80% filled with normal tissue. 相似文献