全文获取类型
收费全文 | 5274篇 |
免费 | 482篇 |
专业分类
林业 | 13篇 |
农学 | 52篇 |
5篇 | |
综合类 | 7篇 |
农作物 | 1篇 |
水产渔业 | 46篇 |
畜牧兽医 | 5602篇 |
园艺 | 2篇 |
植物保护 | 28篇 |
出版年
2024年 | 7篇 |
2023年 | 90篇 |
2020年 | 169篇 |
2018年 | 122篇 |
2017年 | 134篇 |
2016年 | 87篇 |
2015年 | 140篇 |
2014年 | 225篇 |
2013年 | 247篇 |
2012年 | 181篇 |
2011年 | 220篇 |
2010年 | 179篇 |
2009年 | 255篇 |
2008年 | 160篇 |
2007年 | 102篇 |
2006年 | 91篇 |
2005年 | 87篇 |
2004年 | 144篇 |
2003年 | 148篇 |
2002年 | 166篇 |
2001年 | 159篇 |
2000年 | 122篇 |
1999年 | 121篇 |
1998年 | 177篇 |
1997年 | 185篇 |
1996年 | 165篇 |
1995年 | 169篇 |
1994年 | 142篇 |
1993年 | 161篇 |
1992年 | 186篇 |
1991年 | 158篇 |
1990年 | 191篇 |
1989年 | 132篇 |
1988年 | 119篇 |
1987年 | 148篇 |
1986年 | 66篇 |
1985年 | 87篇 |
1984年 | 86篇 |
1983年 | 82篇 |
1982年 | 38篇 |
1981年 | 18篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1975年 | 6篇 |
1971年 | 7篇 |
1970年 | 11篇 |
1961年 | 7篇 |
1958年 | 4篇 |
排序方式: 共有5756条查询结果,搜索用时 15 毫秒
91.
JOHN L. HAMMERTON 《Weed Research》1962,2(4):274-282
Summary. The results of a pot experiment on the mutual interference between kale and three weed species are reported. The puts were sunk in soil and surrounded by kale plants so as to provide illumination conditions similar to those likely to be found in a field crop of kale. Of the three weed species, Polygonum lapathifolium appeared to be the most, and P. aviculare the least, competitive towards kale. P. persicaria was slightly less competitive than P. lapathifolium . The two latter species were much higher in dry-matter production than P. aviculare and showed greater responses to changes in the number of kale or weed plants per pot. 相似文献
92.
93.
94.
Kevin Kline PhD Leonard P. Frey PhD Jonathan H. Foreman DVM MS Joseph T. Lyman DVM MS 《Journal of Equine Veterinary Science》2005,25(8):349-354
Changes in blood gases, pH, and plasma electrolyte concentrations in response to intravenously infused sodium bicarbonate (NaHCO3) and sodium acetate (NaCH3CO2) solutions (1.34 mEq/mL) in 5 light breed mares were investigated. Jugular venous blood samples were collected before and after completion of the infusions in 20-minute intervals for 200 minutes. Infusion of sodium bicarbonate and sodium acetate caused significant (P < .00l) increases in blood pH and bicarbonate ion concentration that persisted throughout the collection period. The elevation in blood pH and bicarbonate ion concentrations was greater (P < .01) for sodium bicarbonate than for sodium acetate immediately after the completion of the infusions but was not different (P > .05) thereafter. There were significant reductions (P < .01) in plasma-ionized calcium and potassium after infusion of both sodium bicarbonate and sodium acetate. This study found that significant metabolic alkalosis in horses and corresponding shifts in electrolyte concentrations can be induced by intravenous infusion of solutions of either sodium bicarbonate or sodium acetate, and they persist for at least 3 hours. These data show that the short-term elevation in pH and bicarbonate ion concentration is momentarily higher after infusion of sodium bicarbonate. This is likely due to the direct infusion of bicarbonate ions in the sodium bicarbonate treatment, such that further metabolism is not required to be effective. However, the longer-term alkalosis did not differ between isomolar solutions of sodium bicarbonate and sodium acetate. 相似文献
95.
96.
How to perform transvenous electrical cardioversion in horses with atrial fibrillation 总被引:1,自引:1,他引:1
M. Kimberly J. McGurrin DVM Dipl ACVIM Peter W. Physick-Sheard BVSc MSc FRCVS Daniel G. Kenney DVM Dipl ACVIM 《Journal of Veterinary Cardiology》2005,7(2):109
Electrical cardioversion of atrial fibrillation is a well-established technique for restoration of sinus rhythm in humans. While transthoracic cardioversion is more commonly used, transvenous electrical cardioversion (TVEC) has been reported as having higher efficacy at substantially lower energy levels. In horses, treatment of atrial fibrillation has essentially been limited to the administration of quinidine salts either orally or intravenously. TVEC provides an alternative to quinidine salts, especially for those animals in which quinidine is neither effective nor tolerated. The present report details this technique in horses, discusses possible complications of the procedure, and provides guidance for successful outcome. Still and video images are used to illustrate details with regard to TVEC techniques in horses. Please view supplemental material for the videos. 相似文献
97.
98.
J. F. McConnell BVM&S DVR DipECDVI Cert. SAM MRCVS L. Garosi DVM S. R. Platt BVM&S 《Veterinary radiology & ultrasound》2005,46(1):1-10
The magnetic resonance imaging (MRI) findings of presumed cerebrovascular accident in 12 dogs are described. Fourteen lesions were seen, commonly (11 of 14) within the gray matter of the cerebellar hemispheres or vermis. Thirteen lesions were hyperintense on T2-weighted images (in 11 dogs) and one was hypointense. Eleven of 14 lesions were within the region supplied by the rostral cerebellar artery or one of its main branches and there was no, or minimal, mass effect. Contrast enhancement was only seen in six lesions and was mild in all. Gradient-echo images provided additional information in two dogs. The appearance of infarction in dogs with diffusion-weighted images (DWI) is similar to that in humans, and provided supportive evidence for the diagnosis of infarction in five dogs. The use of gradient-echo and DWI is recommended for the evaluation of suspected cerebrovascular accidents in dogs. Six of the 12 affected animals were spaniels or spaniel crosses, suggesting a possible breed predisposition. 相似文献
99.
Sandy I. Wang DVM Kyle G. Mathews DVM MS Ian D. Robertson BVSc Marty Stebbins DVM PhD Brian J. Trumpatori BS 《Veterinary radiology & ultrasound》2005,46(1):39-43
Acetabular angles (AAs) and dorsal acetabular rim angles acquired by computed tomographic (CT) imaging have been used to assess patient response to juvenile pubic symphysiodesis surgery. The purpose of this study was to evaluate the effects of patient positioning and slice selection on these angles, and an attempt was made to devise a repeatable method of measuring these angles that would eliminate positioning effects. We found significant variation in AAs with small differences in pelvic tilt and slice selection. Dorsal acetabular rim angles were not affected. As a result of positioning differences from one CT study to the next, every attempt should be made to standardize pelvic tilt, or eliminate its effect on AAs by standardizing gantry angle in relation to an anatomic landmark that will not change over time. The floor of the sacral vertebral canal may be a reasonable landmark for this purpose and deserves further study. 相似文献
100.
Olga Seco Diaz MRCVS Anne Desrochers DMV Vickie Hoffmann VMD Virginia B. Reef DVM 《Veterinary radiology & ultrasound》2005,46(1):83-85
An 8-day-old Arabian-Morgan cross colt underwent cardiac evaluation. The foal was tachycardic, tachypneic, exercise intolerant and had a loud right-sided heart murmur and cyanotic mucous membranes. Total anomalous pulmonary venous connection was diagnosed with echocardiography and confirmed at postmortem examination. Total anomalous pulmonary venous connection is a very rare congenital cardiac abnormality that has not been reported before in the horse. 相似文献