全文获取类型
收费全文 | 484篇 |
免费 | 33篇 |
国内免费 | 32篇 |
专业分类
林业 | 21篇 |
农学 | 11篇 |
基础科学 | 14篇 |
45篇 | |
综合类 | 137篇 |
农作物 | 17篇 |
水产渔业 | 18篇 |
畜牧兽医 | 246篇 |
园艺 | 21篇 |
植物保护 | 19篇 |
出版年
2024年 | 5篇 |
2023年 | 14篇 |
2022年 | 13篇 |
2021年 | 9篇 |
2020年 | 19篇 |
2019年 | 19篇 |
2018年 | 13篇 |
2017年 | 29篇 |
2016年 | 11篇 |
2015年 | 21篇 |
2014年 | 29篇 |
2013年 | 28篇 |
2012年 | 37篇 |
2011年 | 24篇 |
2010年 | 36篇 |
2009年 | 24篇 |
2008年 | 28篇 |
2007年 | 11篇 |
2006年 | 16篇 |
2005年 | 16篇 |
2004年 | 9篇 |
2003年 | 6篇 |
2002年 | 6篇 |
2001年 | 12篇 |
2000年 | 9篇 |
1999年 | 3篇 |
1998年 | 8篇 |
1997年 | 7篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 11篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1983年 | 3篇 |
1978年 | 2篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1969年 | 3篇 |
1968年 | 4篇 |
1965年 | 2篇 |
1963年 | 3篇 |
1960年 | 1篇 |
1943年 | 1篇 |
1901年 | 1篇 |
排序方式: 共有549条查询结果,搜索用时 343 毫秒
221.
河西绿洲膜下滴灌调亏对食用向日葵耗水特征、光合特性及品质的影响 总被引:1,自引:0,他引:1
于2019年在张掖市益民灌溉试验站进行食用向日葵膜下滴灌调亏大田试验,探究在现蕾期、开花期和灌浆期充分灌溉条件下,苗期轻度—成熟期(轻度、中度)水分调亏、苗期中度—成熟期(轻度、中度)水分调亏、苗期重度—成熟期(轻度、中度)水分调亏处理分别对食用向日葵耗水、光合特性、品质及产量的影响,为河西绿洲冷凉灌区优质高产高效种植食用向日葵提供理论依据。结果表明:(1)苗期和成熟期食用向日葵的阶段耗水量、耗水模数、日耗水强度均随水分调亏程度增加而降低,与充分灌溉相比,苗期水分调亏处理阶段耗水量、耗水模数、日耗水强度降幅分别为10.10%~46.08%,7.57%~34.58%,10.68%~46.60%,成熟期水分调亏处理阶段耗水量、耗水模数、日耗水强度降幅分别为5.50%~30.29%,2.93%~16.72%,5.56%~30.34%,苗期重度水分调亏经后期复水补偿作用有限;(2)苗期重度和成熟期中度水分调亏显著降低食用向日葵叶片净光合速率、气孔导度和蒸腾速率(P0.05),与充分灌溉相比,苗期重度水分调亏的降幅分别为40.30%~45.98%,43.99%~47.37%,38.20%~42.10%,成熟期中度水分调亏的降幅分别为14.23%~32.07%,15.98%~51.23%,10.02%~28.45%;(3)苗期中度—成熟期轻度处理品质最优,其粗脂肪含量与粗蛋白含量较充分灌溉分别显著提高10.84%,14.90%(P0.05)。(4)苗期中度—成熟期轻度水分调亏处理产量为4 145 kg/hm~2,与对照CK处于同一水平,产量无明显降低情况,具有节水、调质作用。综合考虑食用向日葵耗水量、光合特性、品质及产量等指标,在其他生育期充分灌溉条件下,进行苗期中度—成熟期轻度水分调亏,作为当地食用向日葵节水优质最优调亏灌溉模式。 相似文献
222.
223.
224.
P H Rowland S A Center S A Dougherty 《Journal of the American Veterinary Medical Association》1992,200(3):348-350
Administration of trimethoprim-sulfadiazine in a dog was associated with vomiting, inappetence, and icterus, and high values of alanine transaminase, aspartate transaminase, alkaline phosphatase, gamma-glutamyltransferase, and total bilirubin concentration. The clinical signs and biochemical abnormalities resolved after discontinuation of the treatment. Histologic examination of sections from a liver biopsy specimen revealed moderate, predominantly portal hepatitis with cholestasis. 相似文献
225.
R A Hitchcock R B Muntifering N W Bradley A A Wahab C T Dougherty 《Journal of animal science》1990,68(9):2848-2851
A grazing trial was conducted with six half-sib yearling Angus steers (average initial weight 281 kg) to quantitate nutrient composition and voluntary intake of vegetative regrowth forage in low-endophyte (Acremonium coenophialum Morgan-Jones and Gams) Kentucky-31 tall fescue (Festuca arundinacea Schreb.) pasture. A new .6-ha section in each of two 3.0-ha pastures (three steers/pasture) was clipped to a 5-cm height on five consecutive days to establish a series of plots that could be grazed continuously during 5-d test periods at uniform stages of vegetative regrowth; each period represented a specific regrowth stage (7, 14, 21, 28 and 35 d). Steers were conditioned by training them to graze to satiety while tethered with an adjustable-length rope to a 1-m galvanized steel post. Grazing time was limited to two sessions daily beginning at 0800 and 1400, and satiety was achieved after no more than 2.5 h of continuous grazing in each session. Forage DM availability was controlled by adjusting tether length and was set each day at 4% of steer BW. Fecal DM output was measured by chromic oxide dilution. A quadratic (P less than .05) effect of regrowth stage was observed for forage contents of NDF and ADF due to abrupt increases in both fractions at wk 5; values for ADL were unaffected by stage of forage regrowth. Forage contents of CP and ash showed a cubic (P less than .05) response to advancing stage of regrowth, with highest (23.6 and 11.0%, respectively) and lowest (14.7 and 9.1%, respectively) values for both fractions occurring at wk 1 and 5, respectively.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
226.
Steve C. Haskins DVM MS Virginia S. Copland DVM John D. Patz BA 《Journal of Veterinary Emergency and Critical Care》1991,1(2):32-38
Blood was withdrawn from 15 dogs over the course of about 1 hour until the mean arterial blood pressure was reduced to 60 mm Hg. Small aliquots of additional blood were withdrawn in order to maintain the mean arterial blood pressure near 60 mm Hg for an additional hour. Oxymorphone (0.4 mg/kg) was then administered intravenously to ten dogs, and all measurements were repeated in 5, 15, 30, and 60 minutes. Five dogs served as controls.
Heart rate, tidal volume, arterial oxygen, oxygen extraction, and pH significantly decreased after oxymorphone administration, while systemic and pulmonary arterial blood pressures, systemic vascular resistance (transiently), breathing rate, minute ventilation, physiologic dead space, venous admixture, venous oxygen, arterial and venous carbon dioxide, and bicarbonate concentration increased significantly. Cardiac output was also increased, but the change was not statistically significant. Oxymorphone was associated with significantly lower heart rate, tidal volume, arterial oxygen, and pH, and higher systemic and pulmonary arterial pressure, cardiac output, venous oxygen, and arterial and venous carbon dioxide, compared to the control group, which did not receive oxymorphone.
Oxymorphone significantly improved cardiovascular performance and tissue perfusion in these hypovolemic dogs. Oxymorphone did cause a significant increase in arterial carbon dioxide and a decrease in arterial oxygenation. Oxymorphone is an opioid agonist that may represent a reasonable alternative for the induction of anesthesia in patients who are candidates for induction hypotension. 相似文献
Heart rate, tidal volume, arterial oxygen, oxygen extraction, and pH significantly decreased after oxymorphone administration, while systemic and pulmonary arterial blood pressures, systemic vascular resistance (transiently), breathing rate, minute ventilation, physiologic dead space, venous admixture, venous oxygen, arterial and venous carbon dioxide, and bicarbonate concentration increased significantly. Cardiac output was also increased, but the change was not statistically significant. Oxymorphone was associated with significantly lower heart rate, tidal volume, arterial oxygen, and pH, and higher systemic and pulmonary arterial pressure, cardiac output, venous oxygen, and arterial and venous carbon dioxide, compared to the control group, which did not receive oxymorphone.
Oxymorphone significantly improved cardiovascular performance and tissue perfusion in these hypovolemic dogs. Oxymorphone did cause a significant increase in arterial carbon dioxide and a decrease in arterial oxygenation. Oxymorphone is an opioid agonist that may represent a reasonable alternative for the induction of anesthesia in patients who are candidates for induction hypotension. 相似文献
227.
228.
229.
230.
Mark J. Acierno MBA DVM DACVIM Verna F. Serra BA Meghan E. Johnson BS Mark A. Mitchell DVM MS PhD 《Journal of Veterinary Emergency and Critical Care》2008,18(5):477-479
Objective – To evaluate the sensitivity and specificity of a newly available, semi‐quantitative, cage‐side test for the detection of ethylene glycol (EG) toxicosis in cats. Design – Prospective, laboratory study. Setting – University teaching hospital. Animals – This study utilized samples from 57 cats, whose blood had been anticoagulated with EDTA and submitted to the hospital's laboratory for a complete blood count. Samples were centrifuged, and the plasma separated, aliquoted, and immediately frozen at ?30 °C. Interventions – Samples were randomly divided into 2 primary groups (Group 1: no EG added, Group 2: EG added). Twenty microliters of plasma from each of the Group 1 samples was applied directly to the test strip. Plasma samples from Group 2 had EG added at different concentrations to achieve approximate final concentrations of 20, 60, or 80 mg/dL. These samples were then applied to the test strip. Measurements – Two readers who were blinded to the sample preparation procedure and isolated from each other were asked to categorically interpret the colorimetric reaction on the randomly presented test strips. Main Results – The agreement of the 2 reviewers at the 3 different levels of EG concentrations (20, 60, 80 mg/dL) were 0.7, 0.7, and 0.5, respectively. Thus, the readers demonstrated substantial agreement while reading the 2 lower concentrations, while at 80 mg/dL the level of agreement was moderate. Overall, the sensitivity of the assay increased as the concentration of EG increased (reviewer 1: 67%, 67%, 86%; reviewer 2: 56%, 89%, 100%), while the specificity of the assay decreased with increasing concentrations of EG (reviewer 1: 77%, 45%, 50%; reviewer 2: 77%, 53%, 25%). Conclusions: Because of the likelihood for false negatives and false positives, results from this test must be viewed in light of clinical data and should not be relied upon as a lone diagnostic test. 相似文献