全文获取类型
收费全文 | 1252篇 |
免费 | 50篇 |
国内免费 | 4篇 |
专业分类
林业 | 67篇 |
农学 | 28篇 |
基础科学 | 18篇 |
244篇 | |
综合类 | 162篇 |
农作物 | 61篇 |
水产渔业 | 94篇 |
畜牧兽医 | 492篇 |
园艺 | 36篇 |
植物保护 | 104篇 |
出版年
2023年 | 6篇 |
2022年 | 12篇 |
2021年 | 15篇 |
2020年 | 18篇 |
2019年 | 27篇 |
2018年 | 25篇 |
2017年 | 15篇 |
2016年 | 15篇 |
2015年 | 21篇 |
2014年 | 18篇 |
2013年 | 61篇 |
2012年 | 72篇 |
2011年 | 89篇 |
2010年 | 62篇 |
2009年 | 57篇 |
2008年 | 83篇 |
2007年 | 81篇 |
2006年 | 87篇 |
2005年 | 70篇 |
2004年 | 72篇 |
2003年 | 79篇 |
2002年 | 85篇 |
2001年 | 13篇 |
2000年 | 13篇 |
1999年 | 14篇 |
1998年 | 16篇 |
1997年 | 11篇 |
1996年 | 12篇 |
1995年 | 10篇 |
1994年 | 9篇 |
1993年 | 10篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 10篇 |
1987年 | 9篇 |
1986年 | 12篇 |
1985年 | 11篇 |
1984年 | 9篇 |
1983年 | 11篇 |
1982年 | 7篇 |
1981年 | 3篇 |
1980年 | 7篇 |
1978年 | 4篇 |
1976年 | 2篇 |
1975年 | 6篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1967年 | 2篇 |
排序方式: 共有1306条查询结果,搜索用时 31 毫秒
991.
Objectives— To compare monotonic biomechanical properties and fatigue life of a 5.5 mm broad limited‐contact dynamic compression plate (5.5‐LC‐DCP) fixation with a 4.5 mm broad LC‐DCP (4.5‐LC‐DCP) fixation to repair osteotomized equine third metacarpal (MC3) bones. Study Design— In vitro biomechanical testing of paired cadaveric equine MC3 with a mid‐diaphyseal osteotomy, stabilized by 1 of 2 methods for fracture fixation. Sample Population— Adult equine cadaveric MC3 bones (n=18 pair). Methods— MC3 were divided into 3 test groups (6 pairs each) for: (1) 4‐point bending single cycle to failure testing; (2) 4‐point bending cyclic fatigue testing; and (3) torsional single cycle to failure testing. The 8‐hole, 5.5 mm broad LC‐DCP (5.5‐LC‐DCP) was applied to the dorsal surface of 1 randomly selected bone from each pair. One 8‐hole, 4.5 mm broad LC‐DCP (4.5‐LC‐DCP) was applied dorsally to the contralateral bone from each pair. Plates and screws were applied using standard ASIF techniques. All MC3 bones had mid‐diaphyseal osteotomies. Mean test variable values for each method were compared using a paired t–test within each group. Significance was set at P<.05. Results— Mean yield load, yield bending moment, composite rigidity, failure load and failure bending moment under 4‐point bending, single cycle to failure, of the 5.5‐LC‐DCP fixation were significantly greater (P<.024) than those of the 4.5‐LC‐DCP fixation. Mean cycles to failure for 4‐point bending was significantly (P<.05) greater for the 4.5‐LC‐DCP fixation compared with the 5.5‐LC‐DCP fixation. Mean yield load, mean composite rigidity, and mean failure load in torsion for the 5.5‐LC‐DCP fixation was not significantly different (P>.05) than those with the 4.5‐LC‐DCP fixation. Conclusion— 5.5‐LC‐DCP fixation was superior to 4.5‐LC‐DCP fixation in resisting the static overload forces under palmarodorsal 4‐point bending. There was no significant difference between 5.5‐LC‐DCP fixation and 4.5‐LC‐DCP fixation in resisting static overload forces under torsion; however, the 5.5‐LC‐DCP offers significantly less stability (80% of that of the 4.5‐LC‐DCP) in cyclic fatigue testing. Clinical Relevance— The results of this in vitro study may provide information to aid in the selection of a biological plate for long bone fracture repair in horses. 相似文献
992.
As part of wildlife surveillance for bovine tuberculosis, pooled lymph nodes from 21,481 ferrets, 1056 stoats and 83 weasels were cultured for mycobacteria. A total of 268 isolates of Mycobacterium bovis were obtained from ferrets, 2 from stoats and none from weasels, demonstrating the presence of a wildlife reservoir of infection in ferrets. DNA typing by restriction endonuclease analysis (REA) of 48 selected isolates of M. bovis revealed 23 REA types. Twenty-one of these types had previously been isolated from cattle and farmed deer, demonstrating a complex cycle of infection involving wildlife and domestic animals. Apart from M. bovis, a further 208 mycobacterial isolates were obtained, the majority of which (178) were members of the M. avium complex. Speciation of the remaining 30 mycobacterial isolates by DNA sequencing of the 16s rRNA gene, identified half the isolates as M. triplex. Other species identified included M. fortuitum, M. florentinum, M. interjectum, M. intracellulare, M. holsaticum, and M. septicum/M. peregrinum. 相似文献
993.
Garry O Kelley Francisco J Zagmutt-Vergara Christian M Leutenegger Karin A Myklebust Mark A Adkison Terry S McDowell Gary D Marty Alex L Kahler Arla L Bush Ian A Gardner Ronald P Hedrick 《Journal of veterinary diagnostic investigation》2004,16(3):202-211
Diagnostic methods were used to identify and quantify Myxobolus cerebralis, a myxozoan parasite of salmonid fish. In this study, 7-week-old, pathogen-free rainbow trout (Oncorhynchus mykiss) were experimentally infected with M. cerebralis and at 7 months postinfection were evaluated with 5 diagnostic assays: 1) pepsin-trypsin digest (PTD) to detect and enumerate spores found in cranial cartilage, 2) 2 different histopathology grading scales that provide a numerical score for severity of microscopic lesions in the head, 3) a conventional single-round polymerase chain reaction (PCR), 4) a nested PCR assay, and 5) a newly developed quantitative real-time TaqMan PCR. There were no significant differences (P > 0.05) among the 5 diagnostic assays in distinguishing between experimentally infected and uninfected control fish. The 2 histopathology grading scales were highly correlated (P < 0.001) for assessment of microscopic lesion severity. Quantification of parasite levels in cranial tissues using PTD and real-time TaqMan PCR was significantly correlated r = 0.540 (P < 0.001). Lastly, 104 copies of the 18S rDNA gene are present in the M. cerebralis genome, a feature that makes this gene an excellent target for PCR-based diagnostic assays. Also, 2 copies of the insulin growth factor-I gene are found in the rainbow trout genome, whose detection can serve both as an internal quality control for amplifiable DNA and as a basis to quantify pathogen genome equivalents present in quantitative PCR assays. 相似文献
994.
Feary DJ Magdesian KG Aleman MA Rhodes DM 《Journal of the American Veterinary Medical Association》2007,231(2):259-266
OBJECTIVE: To investigate the clinical, clinicopathologic, and diagnostic characteristics; treatment; and outcome associated with acute traumatic brain injury (TBI) in horses and assess risk factors for nonsurvival in TBI-affected horses. DESIGN: Retrospective case series. ANIMALS: 34 horses with TBI. Procedures-Medical records of horses that had sustained trauma to the head and developed neurologic signs were reviewed. Data that included signalment, clinicopathologic findings, diagnosis, treatment, and outcome were analyzed. Clinicopathologic variables among horses in survivor and nonsurvivor groups were compared, and risk factors for nonsurvival were determined. RESULTS: Median age of affected horses was 12 months. Findings of conventional survey radiography of the head alone failed to identify all horses with fractures of the calvarium. Horses with basilar bone fractures were 7.5 times as likely not to survive as horses without this type of fracture. Depending on clinical signs, horses received supportive care, osmotic or diuretic treatments, antimicrobials, anti-inflammatory drugs, analgesics, or anticonvulsants. Twenty-one (62%) horses survived to discharge from the hospital. In the nonsurvivor group, mean PCV was significantly higher, compared with the value in the survivor group (40% vs 33%). Risk factors associated with nonsurvival included recumbency of more than 4 hours' duration after initial evaluation (odds ratio, 18) and fracture of the basilar bone (odds ratio, 7.5). CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that prognosis for survival in horses with acute TBI may be more favorable than previously reported. Among horses with TBI, persistent recumbency and fractures involving the basilar bones were associated with a poor prognosis. 相似文献
995.
Objectives— To compare in vitro monotonic biomechanical properties of an equine spoon plate (ESP) with an axial 3‐hole, 4.5 mm narrow dynamic compression plate (DCP) using 5.5 mm cortical screws in conjunction with 2 abaxial transarticular 5.5 mm cortical screws (DCP‐TLS) inserted in lag fashion for equine proximal interphalangeal (PIP) joint arthrodesis. Study Design— Paired in vitro biomechanical testing of 2 methods of stabilizing cadaveric adult equine forelimb PIP joints. Animal Population— Cadaveric adult equine forelimbs (n=18 pairs). Methods— For each forelimb pair, 1 PIP joint was stabilized with an ESP (8 hole, 4.5 mm) and 1 with an axial 3‐hole narrow DCP (4.5 mm) using 5.5 mm cortical screws in conjunction with 2 abaxial transarticular 5.5 mm cortical screws inserted in lag fashion. Six matching pairs of constructs were tested in single cycle to failure under axial compression with load applied under displacement control at a constant rate of 5 cm/s. Six construct pairs were tested for cyclic fatigue under axial compression with cyclic load (0–7.5 kN) applied at 6 Hz; cycles to failure were recorded. Six construct pairs were tested in single cycle to failure under torsional loading applied at a constant displacement rate (0.17 radians/s) until rotation of 0.87 radians occurred. Mean values for each fixation method were compared using a paired t‐test within each group with statistical significance set at P<.05. Results— Mean yield load, yield stiffness, and failure load for ESP fixation were significantly greater (for axial compression and torsion) than for DCP‐TLS fixation. Mean (± SD) values for the ESP and DCP‐TLS fixation techniques, respectively, in single cycle to failure under axial compression were: yield load 123.9 ± 8.96 and 28.5 ± 3.32 kN; stiffness, 13.11 ± 0.242 and 2.60 ± 0.17 kN/cm; and failure load, 144.4 ± 13.6 and 31.4 ± 3.8 kN. In single cycle to failure under torsion, mean (± SD) values for ESP and DCP‐TLS, respectively, were: stiffness 2,022 ± 26.2 and 107.9 ± 11.1 N m/rad; and failure load: 256.4 ± 39.2 and 87.1 ± 11.5 N m. Mean cycles to failure in axial compression of ESP fixation (622,529 ± 65,468) was significantly greater than DCP‐TLS (95,418 ± 11,037). Conclusion— ESP was superior to an axial 3‐hole narrow DCP with 2 abaxial transarticular screws inserted in lag fashion in resisting static overload forces and cyclic fatigue. Clinical Relevance— In vitro results support further evaluation of ESP for PIP joint arthrodesis in horses. Its specific design may provide increased stability without need for external coaptation support. 相似文献
996.
Griebel PJ Entrican G Rocchi M Beskorwayne T Davis WC 《Veterinary immunology and immunopathology》2007,119(1-2):115-122
A panel of 377 commercially available mAbs was submitted to the animal homologue section of the Eighth International Workshop on Human Leukocyte Differentiation Antigens (HLDA8, Adelaide, Australia) for cross-reactivity studies in a range of vertebrate species. Eight commercial suppliers participated by providing isotype controls and mAbs specific for a total of 144 CD antigens. In this study, we describe the results of flow cytometric testing of the reactivity of these mAbs with leukocyte populations isolated from blood, bronchoalveolar lavage, and ileal Peyer's patches of sheep. A total of 52 mAbs were identified as potentially reacting with sheep blood leukocytes in the first round of screening with blood leukocytes. In the second phase, reactivity of selected mAbs was further analyzed by repeating the screening with blood leukocytes at an independent facility. Screening of selected mAbs for reactivity with myeloid antigens was completed with alveolar macrophages and screening for reactivity with B cell antigens was completed with ileal Peyer's patch B cells. This screening identified mAbs that consistently reacted with both putative myeloid (CD10, CD22, CD23, CD27, CD29, CD32, CD49d, CD81, CD86, CD88, CD163, CD165) and B cell (CD10, CD22, CD23, CD27, CD29, CD32, CD49d, CD81, CD86, CD88, CD165) activation or differentiation antigens. Further studies will be required to determine if each mAb cross-reacts with an orthologous leukocyte antigen. 相似文献
997.
Zieba DA Klocek B Williams GL Romanowicz K Boliglowa L Wozniak M 《Domestic animal endocrinology》2007,33(3):358-365
Recent observations in seasonal-breeding mammals indicate that the hypothalamus is programmed to become leptin resistant during long days (LD) and leptin sensitive during short days (SD). These observations support the possibility that photoperiod mediates at least part of its effects on melatonin secretion through changes in leptin sensitivity. Herein we examined the interaction of season and recombinant ovine leptin (oleptin) on melatonin secretion by pineal explants in short-term culture. Glands were collected after sunset from eight ewes during LD (March, April, May, June) and from an additional eight ewes during SD (September, October, November, December). Glands were transected saggitally and coronally into quarters, with each equilibrated in 2.5ml of DMEM for 120min, followed by a 3h incubation in medium containing either 0 or 50ng/ml of oleptin. Treatment with oleptin reduced (P<0.001) melatonin secretion compared to controls during LD by approximately 22% at 2, 2.5 and 3h of culture. However, in cultures from glands collected during SD, oleptin stimulated (P<0.078) melatonin secretion approximately 50% compared to control. These effects were consistent throughout each respective season. We conclude that the secretion of melatonin from the ovine pineal gland is negatively responsive to leptin during LD, whereas leptin may stimulate melatonin secretion during SD. 相似文献
998.
999.
The Use of Recombinant Tissue Plasminogen Activator (rTPA) in The Treatment of Fibrinous Pleuropneumonia in Horses: 25 Cases (2007–2012)
下载免费PDF全文
![点击此处可从《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》网站下载免费的PDF全文](/ch/ext_images/free.gif)
1000.
Since 1986 a novel type of shoot orchard has been under development. Lower portions of the donor stems are buried horizontally in the soil and cuttings are taken from shoots that arise from them. This process apparently rejuvenates, so that mature trees of various ages can be propagated vegetatively. Seedlings of superior provenances, open-pollinated, and control-pollinated families, stump sprouts and upper branches of plus trees were used to establish the orchard, which contains about 40,000 donors and occupies 1.3 ha. Cuttings produced in this orchard can be rooted to about 85% success without hormones or shading. This shoot orchard provides more planting stock, and provides it five to six years earlier, than a seed orchard. The height and root-collar diameter of the rooted cuttings are greater than those of seedlings at outplant, and production costs are 15–20% lower than those associated with seedling production. Test plantations demonstrated that four-year height and diameter of cuttings and genetically similar seedlings are equivalent. This paper reports the details of this orchard, and summarizes other work on propagation and storage of Chinese fir cuttings. 相似文献