全文获取类型
收费全文 | 5615篇 |
免费 | 527篇 |
专业分类
林业 | 63篇 |
农学 | 11篇 |
基础科学 | 2篇 |
179篇 | |
综合类 | 43篇 |
农作物 | 45篇 |
水产渔业 | 59篇 |
畜牧兽医 | 5657篇 |
园艺 | 20篇 |
植物保护 | 63篇 |
出版年
2024年 | 10篇 |
2023年 | 96篇 |
2022年 | 13篇 |
2021年 | 33篇 |
2020年 | 205篇 |
2019年 | 28篇 |
2018年 | 150篇 |
2017年 | 162篇 |
2016年 | 122篇 |
2015年 | 164篇 |
2014年 | 256篇 |
2013年 | 285篇 |
2012年 | 222篇 |
2011年 | 260篇 |
2010年 | 189篇 |
2009年 | 262篇 |
2008年 | 180篇 |
2007年 | 120篇 |
2006年 | 110篇 |
2005年 | 108篇 |
2004年 | 179篇 |
2003年 | 168篇 |
2002年 | 189篇 |
2001年 | 162篇 |
2000年 | 126篇 |
1999年 | 120篇 |
1998年 | 171篇 |
1997年 | 181篇 |
1996年 | 159篇 |
1995年 | 160篇 |
1994年 | 140篇 |
1993年 | 150篇 |
1992年 | 175篇 |
1991年 | 147篇 |
1990年 | 186篇 |
1989年 | 132篇 |
1988年 | 113篇 |
1987年 | 145篇 |
1986年 | 57篇 |
1985年 | 78篇 |
1984年 | 82篇 |
1983年 | 80篇 |
1982年 | 37篇 |
1981年 | 12篇 |
1980年 | 8篇 |
1977年 | 4篇 |
1975年 | 3篇 |
1964年 | 1篇 |
1962年 | 1篇 |
1961年 | 1篇 |
排序方式: 共有6142条查询结果,搜索用时 31 毫秒
1.
Jennifer B. Grimm DVM MS Kurt A. Grimm DVM MS Stephen K. Kneller DVM MS William J. Tranquilli DVM MS Sonia S. Crochik DVM MS Matthew G. Bischoff DVM Jennifer L. Podolski DVM 《Veterinary radiology & ultrasound》2001,42(5):458-462
The effects of intramuscularly administered medetomidine and butorphanol (MB), and medetomidine, butorphanol, atropine (MBA) on glomerular filtration rate (GFR) were determined in six dogs as measured by 99m-Tc-labeled diethylenetriaminepentaacetic acid (99mTc-DTPA) nuclear scintigraphy. Direct systolic, diastolic, and mean arterial blood pressures and heart rate were measured at regular time intervals before, during, and after GFR calculations. The mean GFR measurement following MB was significantly greater (4.44 ml/min/kg) than following MBA (3.82 ml/min/kg) or saline treatment (3.41 ml/min/kg). There was no significant difference between the mean GFR measurements following MBA injection and following saline injection. Diastolic and mean arterial pressures following MBA injection were significantly higher than the values recorded after either MB or saline alone. Heart rate following MB administration was significantly lower than that recorded for dogs receiving MBA or saline alone. The results of this study indicate that the administration of medetomidine in combination with butorphanol significantly increases total GFR in healthy dogs, while the administration of the combination of medetomidine, butorphanol, and atropine does not. 相似文献
2.
Margaret C. McEntee DVM Donald E. Thrall DVM PhD 《Veterinary radiology & ultrasound》2001,42(3):221-225
Twenty two dogs with an infiltrative lipoma had computed tomographic (CT) images acquired to evaluate the extent of local disease. Ten dogs had undergone at least one cytoreductive surgical procedure (range = 1-3; median = 2) prior to imaging. Twenty dogs had measurable disease on CT images; 2 dogs had diffuse disease at a previous surgical site that could not be measured. Tumor volume (n = 20) ranged from 20 to 5,632 cm3 (median = 345 cm3; mean = 996 cm3). None of the dogs had evidence of bone involvement on the CT images; 2 of the 22 dogs had tumors that did not come into direct contact with osseous structures. All dogs with measurable disease had evidence of a fat opacity mass with variable degrees of muscle infiltration. Eleven of 22 dogs were given intravenous contrast medium prior to image acquisition and there was not evidence of enhancement of the infiltrative lipoma in any dog. Based on CT images, tumors were classified as well-defined in 9 dogs, moderately well-defined in 4, not well-defined in 3 and a mix of well-defined and not well-defined in 6 dogs. Tumors tended to be less well-defined in regions where the infiltrative lipoma interdigitated with normal body fat. It appears CT imaging allows adequate discrimination of tumor with the caveat that differentiation of normal fat from infiltrative lipoma can be problematic. 相似文献
3.
Hege Kippenes DVM Patrick R. Gavin DVM PhD Susan L. Kraft DVM PhD Ronald D. Sande DVM MS PhD Russell L. Tucker DVM 《Veterinary radiology & ultrasound》2001,42(2):130-133
The pituitary gland was measured from transverse magnetic resonance T1-weighted images after Gadolinium administration in 96 dogs weighing from 13 to 45 kg. The measurements were done by hand with calipers. The mean (+/- standard deviation) pituitary gland height was 5.1 mm (+/-0.9 mm). The mean width was 6.4 mm (+/- 1.1 mm). The correlation coefficient between pituitary and brain measurements, between pituitary measurement and body weight, and brain measurements and body weight was 0.0 to 0.3. A hyperintense region was present on T1-weighted images in the center of the pituitary gland in 64% of the dogs. At necropsy the pituitary glands were grossly and histologically normal. No pituitary gland measurements were performed at necropsy. 相似文献
4.
5.
F. F. J. FRANSSEN J. T. LUMEIJ DVM PhD † 《Journal of veterinary pharmacology and therapeutics》1992,15(4):409-415
Six out of eight different Trichomonas gallinae strains isolated from racing pigeons proved to be resistant to the nitroimidazole drugs ronidazole, carnidazole and metronidazole. The minimal cytocidal concentration of ronidazole was determined in in vitro experiments. Moreover, a therapeutic dose for ronidazole was determined for the control of trichomoniasis in pigeons from which the resistant T. gallinae strains were isolated. It was a 5-fold increase of the recommended ronidazole dosage which eliminated the infection in affected pigeons. 相似文献
6.
Precise localization of the needle tip during CT-guided percutaneous biopsy is considered to be a key element of a successful procedure. To ensure accuracy, the true needle tip must be differentiated from a false or simulated tip which appears when the CT slice encompasses only the shaft of an angled needle. By obtaining images of an aspiration biopsy needle inserted vertically into a phantom and then incrementally tilting the gantry, the authors were able to compare the characteristic features of the true tip to the simulated tip. The true tip was abrupt and distinct and had an adjacent flame-like low density artifact. The simulated tip was indistinct and tapered, yet still produced the adjacent artifact. We concluded that the shape and distinctness of the end portion of the needle itself, rather than the attendant artifact, were the most reliable criteria for accurate needle tip identification. 相似文献
7.
8.
Lactate Kinetics in veterinary Critical Care: A Review 总被引:3,自引:0,他引:3
Michael S. Lagutchik DVM Gregory K. Ogilvie DVM Wayne E. Wingfield MS DVM Timothy B. Hackett DVM MS 《Journal of Veterinary Emergency and Critical Care》1996,6(2):81-95.
Elevation in blood lactate concentration, with or without accompanying metabolic acidosis, is a hallmark finding in patients with circulatory compromise, and is also consistently noted in other conditions affecting critically ill or injured individuals. Little is reported in a veterinary literature regarding lactate measurement in the emergency and critical care setting, despite impressive reports of the clinical usefulness of lactate measurement in people. The purpose of this article is to review lactate kinetics and the clinical utility of lactate measurement. Limitations to lactate evaluation will also be discussed. 相似文献
9.
10.
PULMONARY MINERALIZATION IN FOUR DOGS WITH CUSHING'S SYNDROME 总被引:1,自引:0,他引:1
Clifford R. Berry DVM Norman Ackerman DVM Kevin Monce DVM 《Veterinary radiology & ultrasound》1994,35(1):10-16
The clinical and imaging features of four dogs with Cushing's syndrome and pulmonary mineralization are reviewed. Three dogs presented with a primary complaint of respiratory distress/dyspnea. Three dogs had pituitary dependent Cushing's syndrome, while the remaining one dog had iatrogenic Cushing's syndrome. Each dog had clinical features typical for Cushing's syndrome. Two of the dogs were euthanized due to progressive hypoxemia. In each dog, the serum calcium, phosphorous, blood urea nitrogen and creatinine were normal.
A generalized increase in unstructured interstitial pulmonary opacity with diffuse mineralization was noted on thoracic radiographs of all dogs. In one dog, an ill-defined nodular interstitial pattern of mineralization was present. Delayed bone phase scintigraphy using99m Technetium methylene diphosphonate documented generalized pulmonary uptake in two dogs. 99m Technetium labeled microaggregated albumin lung perfusion scans were normal in these two dogs. 99m Tc-MDP scintigraphy can provide useful information in diagnosing pulmonary mineralization in Cushingoid dogs. 相似文献
A generalized increase in unstructured interstitial pulmonary opacity with diffuse mineralization was noted on thoracic radiographs of all dogs. In one dog, an ill-defined nodular interstitial pattern of mineralization was present. Delayed bone phase scintigraphy using