全文获取类型
收费全文 | 357篇 |
免费 | 24篇 |
专业分类
林业 | 1篇 |
农学 | 9篇 |
基础科学 | 1篇 |
22篇 | |
综合类 | 60篇 |
农作物 | 7篇 |
水产渔业 | 24篇 |
畜牧兽医 | 219篇 |
园艺 | 4篇 |
植物保护 | 34篇 |
出版年
2022年 | 4篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 10篇 |
2015年 | 7篇 |
2014年 | 7篇 |
2013年 | 20篇 |
2012年 | 20篇 |
2011年 | 19篇 |
2010年 | 4篇 |
2009年 | 8篇 |
2008年 | 9篇 |
2007年 | 13篇 |
2006年 | 7篇 |
2005年 | 10篇 |
2004年 | 6篇 |
2003年 | 11篇 |
2002年 | 5篇 |
2001年 | 5篇 |
2000年 | 6篇 |
1999年 | 9篇 |
1998年 | 10篇 |
1997年 | 5篇 |
1996年 | 6篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 8篇 |
1988年 | 12篇 |
1987年 | 14篇 |
1986年 | 9篇 |
1985年 | 9篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1972年 | 7篇 |
1971年 | 8篇 |
1970年 | 3篇 |
1969年 | 9篇 |
1968年 | 3篇 |
1967年 | 3篇 |
1966年 | 5篇 |
1908年 | 2篇 |
1885年 | 2篇 |
排序方式: 共有381条查询结果,搜索用时 812 毫秒
51.
Amanda R. Taylor Noah D. Cohen Stephen Fletcher John F. Griffin Jonathan M. Levine 《Veterinary radiology & ultrasound》2013,54(4):332-342
The purpose of this study was to describe application and machine accuracy for a new computed tomography (CT) guided, frameless, stereotactic brain biopsy system in dogs. Heads from ten canine cadavers were secured to a bite‐plate with six attached fiducial markers and imaged using CT. Fiducialized CT images were imported into stereotactic software and spherical phantom lesions between 3.9 and 5.5 mm in diameter were created in six locations. Infrared cameras and reflective markers were used to register fiducials to the reconstructed image set. Coordinates in the X, Y, and Z planes were identified for each lesion center. Iohexol (1.5 μl of 240 mgI/ml) was injected into the center of each lesion and CT scans were repeated. Pre‐ and postinjection CT images for each cadaver were fused using the system software. Application accuracy was calculated using the center of each phantom lesion and the center of each injected contrast material location. Machine accuracy was calculated using a phantom with known distances between four fixed points in the X, Y, and Z planes. Mean application accuracy in the first 5 cadavers was 4.3 mm (95% confidence interval [CI] 2.9–4.3 mm) and in the second 5 cadavers was 2.9 mm (95% CI 2–3.9 mm). The more superficial lesions were targeted significantly less accurately than the deeper lesions (P = 0.0183). Median machine accuracy was 0.1 mm and the range was 0.1–0.2 mm. Findings supported use of the new biopsy system for canine brain lesions >3.9 mm in diameter. 相似文献
52.
B Trigal M Muoz E Gmez JN Caamao D Martin S Carrocera R Casais C Diez 《Reproduction in domestic animals》2013,48(2):200-206
This work analyses the effects of a high hydrostatic pressure (HHP) treatment on in vitro survival of in vitro produced (IVP) bovine embryos vitrified with the Cryologic Vitrification Method (CVM). Consequences on embryo quality in terms of cell proliferation and differentiation, and levels of embryonic Heat Shock Protein 70 (Hsp‐70) were also examined. Day 7 and 8 bovine in vitro‐produced blastocysts were submitted to an HHP treatment (60 MPa, at 32°C for 1 h) and allowed to recover for 1 or 2 h in culture medium. The HHP treatment did not improve blastocyst survival rates after vitrification/warming. Survival (24 h post‐warming) and hatching (48 h post‐warming) rates were 79.3 ± 4.9 and 51.8 ± 4.2 vs 73.9 ± 4.2 and 44.7 ± 4.1 for untreated controls and HHP‐treated embryos, respectively. Total cell numbers measured in fresh embryos were reduced after 1 h at 32°C, with or without HHP treatment, indicating that cell proliferation was stopped as a result of stress. Vitrified HHP‐treated embryos that hatched at 48 h after warming showed increased cell numbers in their ICM compared with untreated controls (50.2 ± 3.1 vs 38.8 ± 2.7), indicating higher embryo quality. Treatment of blastocysts with HHP did not alter the level of the Hsp‐70 protein. In our conditions, HHP treatment did not affect the cryoresistance of these embryos. However, combination of HHP treatment and vitrification in fibreplugs resulted in an increase in the ICM cell number of hatched embryos 48 h post‐warming. 相似文献
53.
Martin LG Groman RP Fletcher DJ Behrend EN Kemppainen RJ Moser VR Hickey KC 《Journal of the American Veterinary Medical Association》2008,233(1):87-95
OBJECTIVE: To evaluate pituitary-adrenal function in critically ill dogs with sepsis, severe trauma, and gastric dilatation-volvulus (GDV). DESIGN: Cohort study. ANIMALS: 31 ill dogs admitted to an intensive care unit (ICU) at Washington State University or the University of Pennsylvania; all dogs had acute critical illness for < 48 hours prior to admission. PROCEDURES: Baseline and ACTH-stimulated serum cortisol concentrations and baseline plasma ACTH concentrations were assayed for each dog within 24 hours after admission to the ICU. The change in cortisol concentrations (Delta-cortisol) was calculated for each dog. Morbidity and mortality data were recorded for each patient. RESULTS: Overall, 17 of 31 (55%) acutely critically ill dogs had at least 1 biochemical abnormality suggestive of adrenal gland or pituitary gland insufficiency. Only 1 (3%) dog had an exaggerated response to ACTH stimulation. Dogs with Delta-cortisol < or = 83 nmol/L were 5.7 times as likely to be receiving vasopressors as were dogs with Delta-cortisol > 83 nmol/L. No differences were detected among dogs with sepsis, severe trauma, or GDV with respect to mean baseline and ACTH-stimulated serum cortisol concentrations, Delta-cortisol, and baseline plasma ACTH concentrations. CONCLUSIONS AND CLINICAL RELEVANCE: Biochemical abnormalities of the hypothalamic-pituitary-adrenal axis indicative of adrenal gland or pituitary gland insufficiency were common in critically ill dogs, whereas exaggerated responses to ACTH administration were uncommon. Acutely ill dogs with Delta-cortisol < or = 83 nmol/L may be more likely to require vasopressors as part of the treatment plan. 相似文献
54.
55.
Transpalpebral ultrasonographic measurement of the optic nerve sheath diameter in healthy dogs
下载免费PDF全文
![点击此处可从《Journal of Veterinary Emergency and Critical Care》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Joshua J. Smith DVM Daniel J. Fletcher PhD DVM DACVECC Stacy D. Cooley DVM DACVR Margret S. Thompson DVM DACVR 《Journal of Veterinary Emergency and Critical Care》2018,28(1):31-38
Objective
To develop a reference range for ultrasonographically measured optic nerve sheath diameter (ONSD‐US) in dogs. We hypothesized that ONSD‐US can be measured reliably and is associated with weight but not age, sex, or body condition score (BCS), and that the relationship between weight and ONSD‐US in dogs is allometric due to canine size variations.Design
Prospective, observational study.Setting
University teaching hospital.Animals
Seventy‐eight healthy adult dogs.Interventions
The ONSD was measured by a standardized transpalpebral approach.Measurements and Main Results
Regression analysis showed the relationship between weight and ONSD was better fit with a linear model (R2 = 0.8510) than an allometric model (R2 = 0.7917). Multiple regression analysis showed ONSD is associated with weight (P < 0.0001), age (P = 0.0021), and BCS (P = 0.0007), but not with sex. Dominance analysis showed 94.6% of the variance explained by the model was due to weight. Intraclass correlation coefficient (ICC) analysis showed excellent interobserver (ICC = 0.9338–0.9608) and intraobserver (ICC = 0.9893) reliability.Conclusions
These results suggest that ONSD‐US may be reliably measured in dogs using our described transpalpebral approach, and we have calculated prediction intervals based on body weight. Future studies are needed to determine if ONSD‐US measurements are associated with intracranial hypertension as shown in human medicine. 相似文献56.
Previous investigations failed to demonstrate mast cells in the alimentary tract and extraparietal glands of the ferret. It was decided therefore to test this and assess factors that may be of influence. Major salivary glands and tongues of mature ferrets, which had been fixed in formalin-calcium, were examined by means of light microscopical histochemistry. Staining of paraffin sections with techniques depending on basic dyes or esterolytic activity was carried out for conventional times with and without previous oxidation, hot acid hydrolysis, and trypsin and beta-glucuronidase digestion. Aldehyde fuchsin and high iron diamine consistently revealed the presence of few mast cells in interstitial stroma of salivary glands and lingual musculature, and in the lamina propria of lingual mucosa. Alcian blue at 0.5 M MgCl2 and safranin produced less consistent results, and even fewer metachromatic mast cells were detected. No staining of mast cells was obtained with the technique for naphthol AS-D chloroacetate esterase. Pretreatment did not increase the numbers and/or staining reactions of mast cells. The results refute the previous misconception and suggest that ferret is a species with a low incidence of mast cells largely expressing a connective-tissue phenotype. 相似文献
57.
Fang H Howroyd PC Fletcher AM Diters RW Woicke J Sasseville VG Bregman CL Freebern WJ Durham SK Mense MG 《Veterinary pathology》2007,44(3):407-410
Subendothelial heart valve angiectasis has been reported in cows, dogs, pigs, rats, mice, and in human fetuses and newborns. We observed a high incidence (62 in 208 animals examined) of spontaneous angiectasis on the atrioventricular (AV) valves in 10- to 40-week-old Sprague-Dawley rats. The angiectasis was observed predominately on the septal cusp of the right AV valve and located near the AV ostium in 57 of 62 animals. Of the remaining 5 valvular angiectases, 2 were present on the parietal cusp of the right AV valve and 3 were on the left AV valve. The angiectases were single or multiple, ranging from 40 to 300 microm in diameter and were characterized by light microscopy as blood-filled dilatations lined by endothelium. Spontaneously occurring abnormalities in normal laboratory animals, such as the spontaneous valvular angiectasis reported here, need to be differentiated from drug-related lesions. 相似文献
58.
F Ronning C Kim DL Feng DS Marshall AG Loeser LL Miller JN Eckstein I Bozovic Z Shen 《Science (New York, N.Y.)》1998,282(5396):2067-2072
An angle-resolved photoemission study is reported on Ca2CuO2Cl2, a parent compound of high-Tc superconductors. Analysis of the electron occupation probability, n(k), from the spectra shows a steep drop in spectral intensity across a contour that is close to the Fermi surface predicted by the band calculation. This analysis reveals a Fermi surface remnant, even though Ca2CuO2Cl2 is a Mott insulator. The lowest energy peak exhibits a dispersion with approximately the &cjs3539;coskxa - coskya&cjs3539; form along this remnant Fermi surface. Together with the data from Dy-doped Bi2Sr2CaCu2O8+delta, these results suggest that this d-wave-like dispersion of the insulator is the underlying reason for the pseudo gap in the underdoped regime. 相似文献
59.
A dielectric omnidirectional reflector 总被引:3,自引:0,他引:3
Y Fink JN Winn S Fan C Chen J Michel JD Joannopoulos EL Thomas 《Science (New York, N.Y.)》1998,282(5394):1679-1682
A design criterion that permits truly omnidirectional reflectivity for all polarizations of incident light over a wide selectable range of frequencies was used in fabricating an all-dielectric omnidirectional reflector consisting of multilayer films. The reflector was simply constructed as a stack of nine alternating micrometer-thick layers of polystyrene and tellurium and demonstrates omnidirectional reflection over the wavelength range from 10 to 15 micrometers. Because the omnidirectionality criterion is general, it can be used to design omnidirectional reflectors in many frequency ranges of interest. Potential uses depend on the geometry of the system. For example, coating of an enclosure will result in an optical cavity. A hollow tube will produce a low-loss, broadband waveguide, whereas a planar film could be used as an efficient radiative heat barrier or collector in thermoelectric devices. 相似文献
60.
Julie A. Churchill Daniel A. Feeney Thomas F. Fletcher Carl A. Osborne David J. Polzin 《Veterinary radiology & ultrasound》1999,40(6):642-647
Under controlled, but varied dietary conditions 35 geriatric, uninephrectomized, spayed Beagle bitches (dogs) observed for 4 years, renal cortical and renal medullary echogenicity was measured relative to hepatic and splenic echogenicity. Regardless of the diet fed, 60-75% of these aged dogs had renal cortical echogenicity less than that of either the liver or spleen across time; 25-35% of these dogs had renal cortical echogenicity equal to that of the liver, but less than that of the spleen across time. Less than 3% of these dogs had renal cortical echogenicity greater than that of the liver, but less than that of the spleen. Only 1 (one) of these dogs had renal cortical echogenicity equal to that of the spleen and that occurred at only one of the 14 chronologic assessments. Therefore, in either mature or aged dogs imaged with 4.0 to 5.0 MHz equipment, the renal cortical echogenicity should be considered normal if it is less than or equal to that of the liver and less than that of the spleen. In 29 dogs imaged with the 4.0/5.0 MHz equipment and 6 dogs imaged with 7.5 MHz equipment, there was no significant diet or individual dog effect. The 7.5 MHz (6 dog) group had significantly higher average cortical echogenicity scores than the 4.0/5.0 MHz (29 dog) group. However, the occurrence of renal cortical echogenicity greater than liver echogenicity was seen in only 5 of 83 samples (approximately 6.0%) made on 6 dogs imaged with 7.5 MHz equipment and only 1 of 375 samples (approximately 0.27%) made on 29 dogs with 4.0/5.0 MHz equipment. With the exception of one occurrence, all dogs had renal medullary echogenicity less than that of the liver or spleen regardless of imaging equipment frequency. The renal medulla was always hypoechoic compared to the cortex. 相似文献