全文获取类型
收费全文 | 3900篇 |
免费 | 236篇 |
国内免费 | 2篇 |
专业分类
林业 | 332篇 |
农学 | 78篇 |
基础科学 | 17篇 |
671篇 | |
综合类 | 643篇 |
农作物 | 170篇 |
水产渔业 | 359篇 |
畜牧兽医 | 1491篇 |
园艺 | 120篇 |
植物保护 | 257篇 |
出版年
2023年 | 40篇 |
2022年 | 68篇 |
2021年 | 102篇 |
2020年 | 126篇 |
2019年 | 155篇 |
2018年 | 149篇 |
2017年 | 115篇 |
2016年 | 134篇 |
2015年 | 94篇 |
2014年 | 141篇 |
2013年 | 201篇 |
2012年 | 261篇 |
2011年 | 324篇 |
2010年 | 169篇 |
2009年 | 155篇 |
2008年 | 261篇 |
2007年 | 265篇 |
2006年 | 221篇 |
2005年 | 205篇 |
2004年 | 186篇 |
2003年 | 195篇 |
2002年 | 145篇 |
2001年 | 31篇 |
2000年 | 20篇 |
1999年 | 36篇 |
1998年 | 27篇 |
1997年 | 18篇 |
1996年 | 17篇 |
1995年 | 14篇 |
1994年 | 18篇 |
1993年 | 11篇 |
1992年 | 18篇 |
1991年 | 20篇 |
1990年 | 17篇 |
1989年 | 12篇 |
1988年 | 15篇 |
1986年 | 12篇 |
1985年 | 9篇 |
1984年 | 15篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1980年 | 6篇 |
1978年 | 6篇 |
1976年 | 5篇 |
1974年 | 6篇 |
1971年 | 6篇 |
1928年 | 5篇 |
1925年 | 6篇 |
1924年 | 6篇 |
排序方式: 共有4138条查询结果,搜索用时 15 毫秒
51.
52.
Batchelor DJ Noble PJ Cripps PJ Taylor RH McLean L Leibl MA German AJ 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2007,21(2):207-214
BACKGROUND: Knowledge of breed associations is valuable to clinicians and researchers investigating diseases with a genetic basis. HYPOTHESIS: Among symptomatic dogs tested for exocrine pancreatic insufficiency (EPI) by canine trypsin-like immunoreactivity (cTLI) assay, EPI is common in certain breeds and rare in others. Some breeds may be overrepresented or underrepresented in the population of dogs with EPI. Pathogenesis of EPI may be different among breeds. ANIMALS: Client-owned dogs with clinical signs, tested for EPI by radioimmunoassay of serum cTLI, were used. METHODS: In this retrospective study, results of 13,069 cTLI assays were reviewed. RESULTS: An association with EPI was found in Chows, Cavalier King Charles Spaniels (CKCS), Rough-Coated Collies (RCC), and German Shepherd Dogs (GSD) (all P < .001). Chows (median, 16 months) were younger at diagnosis than CKCS (median, 72 months, P < .001), but not significantly different from GSD (median, 36 months, P = .10) or RCC (median, 36 months, P = .16). GSD (P < .001) and RCC (P = .015) were younger at diagnosis than CKCS. Boxers (P < .001), Golden Retrievers (P < .001), Labrador Retrievers (P < .001), Rottweilers (P = .022), and Weimaraners (P = .002) were underrepresented in the population with EPI. CONCLUSIONS AND CLINICAL IMPLICATIONS: An association with EPI in Chows has not previously been reported. In breeds with early-onset EPI, immune-mediated mechanisms are possible or the disease may be congenital. When EPI manifests later, as in CKCS, pathogenesis is likely different (eg, secondary to chronic pancreatitis). Underrepresentation of certain breeds among dogs with EPI has not previously been recognized and may imply the existence of breed-specific mechanisms that protect pancreatic tissue from injury. 相似文献
53.
Lugo J Harkema JR deFeijter-Rupp H Bartner L Boruta D Robinson NE 《Veterinary journal (London, England : 1997)》2006,172(2):293-301
This study was performed to determine if a peripheral sample of lung from the site where biopsy is conducted is representative of the rest of the lung and to investigate the relationship between airway inflammation and intraepithelial mucous production in the peripheral airways. Lung parenchyma samples were collected from five different regions of the lung in five control and five heaves-affected horses. Horse groups were defined by clinical response to stabling. Tissue sections were used for semi-quantitative scoring of lesions, to count the number of airways, to quantify the amount of stored mucosubstances (Vs) within the epithelium, and to count the number of epithelial cells in terminal airways. No significant differences were found between lung regions or between groups of horses. Lack of regional differences in airway structures means that a biopsy sample can be used for diagnosis and investigation of diffusely distributed diseases. Airway inflammation was correlated with mucous cell metaplasia and Vs. Therefore, in horses, mucus accumulation is partly caused by increased number of mucous cells and is associated with airway inflammation. Therapy targeted to reduce airway inflammation will help reduce the excessive mucous accumulation in horses. 相似文献
54.
Petra FRÝDLOVÁ Jan HNÍZDO Lenka CHYLÍKOVÁ Olga ŠIMKOVÁ Veronika CIKÁNOVÁ Petr VELENSKÝ Daniel FRYNTA 《Integrative zoology》2013,8(Z1):39-45
Blood cell morphology and count are not uniform across species. Recently, between‐species comparisons revealed that the size of red blood cells is associated with body size in some lizard taxa, and this finding was interpreted in the context of the metabolic theory. In the present study, we examined the numbers and the size of blood cells in 2 species of monitor lizards, the mangrove‐dwelling monitor (Varanus indicus) and the savannah monitor (V. exanthematicus), and we compared these traits in individuals of different body size. The results revealed that during the course of ontogeny, the size of red blood cells increases with body mass. Because the mass‐specific metabolic rate decreases with body size and the cell volume‐to‐surface ratio decreases with the cell size, changes in the erythrocyte size might be the result of oxygen transport adjustment. 相似文献
55.
56.
Ralph C. Weichsei. Baum DVM Daniel A. Feeney DVM MS David W. Hayden DVM PhD 《Veterinary radiology & ultrasound》1994,35(6):418-426
It was the intent of this study to define which, if any, radiographic observations corresponded with specific causes of diffuse infiltrative small bowel disease and if radiographic findings could differentiate inflammatory disease from neoplastic disease and either of them from normal. Bowel spasticity, luminal narrowing, and thumbprinting tend to indicate the presence of tumor more often than inflammatory disease. Increased bowel gas in cats and barium adhesion in dogs and cats suggest that a component of enteritis is present. Decreased bowel gas in dogs is more often associated with obstructive disease, but is not helpful in differentiating diffuse inflammatory disease from diffuse neoplastic disease. While several observations that can foster differentiation of neoplastic from inflammatory disease were found, this study also indicated that the UGI lacks a high degree of predictive value other than to indicate the presence of infiltrative small bowel disease. 相似文献
57.
Laurie L. Head Gregory B. Daniel Timothy J. Becker David A. Lidbetter 《Veterinary radiology & ultrasound》2005,46(3):263-266
The normal feline pancreas has been evaluated using radiolabeled leukocytes (99mTc-HMPAO) and computed tomography. The purpose of this report is to describe a clinical case where both modalities were utilized to assess the inflamed feline pancreas. A nine year old female cat presented with anorexia, depression and some vomiting. Blood values were unremarkable. Radiographs and ultrasound were suggestive of pancreatitis. The cat's leukocytes were separated and labeled according to an established protocol. Whole body images were acquired immediately, at 5 and 30 min, and at 1, 2, 4, and 17 hours post injection. Approximately 48 h later, the animal was anesthetized and computed tomography of the abdomen was preformed both pre and post contrast. Surgical biopsies were taken. The distribution of the WBCs was similar to that documented in normal animals, however, at 2 h there was faint uptake seen in the region of the pancreas. This uptake became more intense at 4 h and persisted at 17 h. Computed tomography showed irregular margination of the pancreas, it was larger than normal and inhomogeneous. Contrast enhancement was inhomogeneous and its peak enhancement was not reached until 10 min post injection; normal feline pancreas enhances homogeneously and peaks immediately. Histopathology confirmed pancreatitis with lymphocytic, plasmacytic, neutrophilic and eosinophilic inflammation and fibrosis. Radiolabeled leukocytes can be used to document pancreatic inflammation and this is best seen 4 h after injection. Computed tomography allows superior visualization of the pancreas. Both the appearance and contrast enhancement pattern of the inflamed pancreas differ from normal. 相似文献
58.
Jaqueline Mena Carolina Manosalva Ruben Ramirez Lhia Chandia Daniel Carroza Anitsi Loaiza Rafael A. Burgos Maria A. Hidalgo 《Veterinary immunology and immunopathology》2013,151(3-4):275-284
Neutrophils are critical to the innate immune response; therefore, the proper function of neutrophils is critical to avoid the development of certain diseases. Linoleic acid, a polyunsaturated long-chain fatty acid, is one of the most abundant long-chain fatty acids found in the plasma of cows after giving birth. In this study, we evaluated the effects of linoleic acid treatment on bovine neutrophil adhesion, chemotaxis, metalloproteinase (MMP)-9 release, CD11b expression, intracellular calcium mobilisation, mitogen-activating protein kinase (MAPK) phosphorylation and COX-2 and IL-8 expression. Bovine neutrophils isolated from healthy heifers were incubated with different concentrations of linoleic acid, and then neutrophil responses were evaluated. Our results show that the treatment of neutrophils with 100 μM linoleic acid increased their adhesion to the bovine endothelial cell line CPA47. The results of a transwell migration assay revealed that linoleic acid could also promote the chemotaxis of bovine neutrophils. Furthermore, linoleic acid treatment increased MMP-9 activity and CD11b cell surface expression in neutrophils. Fifty and 100 μM linoleic acid also increased intracellular calcium mobilisation in neutrophils loaded with Fluo-4 AM dye. Linoleic acid also rapidly (2–5 min) stimulated the phosphorylation of ERK1/2 and p38 MAPK as evaluated by immunoblot. Finally, COX-2 and IL-8 mRNA expression increased after 2 h of linoleic acid treatment. In conclusion, linoleic acid stimulates adhesion, chemotaxis, granule release and intracellular responses in bovine neutrophils. 相似文献
59.
High hydrostatic pressure processing (HPP) has been shown to be an effective non-thermal means of inactivating microorganisms from various food products. Little information is available regarding the effects of HPP on metazoan parasites. Outbreaks of food-borne disease have been associated with importation of food contaminated with fecal material. Ascaris suum is used as a surrogate model metazoan parasite for the human roundworm, Ascaris lumbricoides, to study the effects of treatments on the inactivation of eggs in sludge. The present study was conducted to determine the effects of HPP on A. suum eggs. Unembryonated A. suum eggs were subjected to 138-552 megapascals (MPa) for 10-60s in a commercial HPP unit. Embryonation was induced after HPP treatments by incubating eggs in 0.01N sulfuric acid at room temperature. After 21 days, 100 eggs were examined per treatment using a light microscope and the percent of embryonated eggs was determined. Embryonation was induced in 38-76% eggs that were subjected to 138 and 270MPa. No embryonation was observed in eggs exposed to pressures of 241MPa or more for 60s or in eggs exposed to 276MPa for 10-30s. These results indicate that HPP treatment could be used to protect contaminated food items by inactivating A. suum eggs and may also have potential in reducing food-borne illness resulting from fecal contamination. 相似文献
60.
Sita S. Withers Daniel York Jin W. Choi Kevin D. Woolard Renee Laufer‐Amorim Ellen E. Sparger Jenna H. Burton Stephen J. McSorley Arta M. Monjazeb William J. Murphy Robert J. Canter Robert B. Rebhun 《Veterinary and comparative oncology》2019,17(3):242-252
Our lack of understanding of the immune microenvironment in canine osteosarcoma (cOSA) has limited the identification of potential immunotherapeutic targets. In particular, our ability to utilize readily available tissue from a dog's primary tumour to predict the type and extent of immune response in their pulmonary metastatic lesions is unknown. We, therefore, collected 21 matched pairs of primary tumours and pulmonary metastatic lesions from dogs with OSA and performed immunohistochemistry to quantify T‐lymphocyte (CD3), FOXP3+ cell, B‐lymphocyte (Pax‐5), and CD204+ macrophage infiltration. We found that T‐lymphocytes and FOXP3+ infiltrates in primary tumours positively correlated with that of metastatic lesions (ρ = 0.512, P = 0.038 and ρ = 0.698, P = 0.007, respectively), while a strong trend existed for CD204+ infiltrates (ρ = 0.404, P = 0.087). We also observed T‐ and B‐lymphocytes, and CD204+ macrophages to be significantly higher in a dog's pulmonary metastasis compared to their primary tumour (P = 0.018, P = 0.018, P = 0.016, respectively), while FOXP3+ cells were only significantly higher in metastases when all primary tumour and metastasis lesions were compared without pairing (P = 0.036). Together, these findings suggest that the metastatic immune microenvironment may be influenced by that of the primary cOSA, and that primary tumour immune biomarkers could potentially be applied to predict immunotherapeutic responses in gross metastatic disease. We, therefore, provide a rationale for the treatment of cOSA pulmonary metastases with immunotherapeutics that enhance the anti‐tumour activity of these immune cells, particularly in dogs with moderate to high immune cell infiltration in their primary tumours. 相似文献