全文获取类型
收费全文 | 175篇 |
免费 | 3篇 |
国内免费 | 1篇 |
专业分类
林业 | 2篇 |
农学 | 1篇 |
12篇 | |
综合类 | 18篇 |
农作物 | 2篇 |
水产渔业 | 1篇 |
畜牧兽医 | 128篇 |
园艺 | 8篇 |
植物保护 | 7篇 |
出版年
2020年 | 3篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 4篇 |
2014年 | 3篇 |
2013年 | 16篇 |
2012年 | 2篇 |
2011年 | 1篇 |
2010年 | 1篇 |
2009年 | 3篇 |
2008年 | 7篇 |
2007年 | 6篇 |
2006年 | 7篇 |
2005年 | 8篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 5篇 |
2001年 | 6篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 7篇 |
1997年 | 7篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 7篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1972年 | 2篇 |
1966年 | 2篇 |
1964年 | 1篇 |
1960年 | 1篇 |
1938年 | 1篇 |
1926年 | 1篇 |
1920年 | 1篇 |
1919年 | 1篇 |
1908年 | 1篇 |
1897年 | 1篇 |
排序方式: 共有179条查询结果,搜索用时 62 毫秒
111.
The bottom sediments of Sörfjord, West Norway, contain unusually high concentrations of Ag, Ba, Bi, Cd, Cu, In, Pb, Sb, Sn, and Zn. The concentrations of Zn and Pb reach ~ 10% by weight in some sediments. The concentrations of most of the elements are positively correlated, those of Pb, Cd, and Cu with Zn being particularly well developed; correlations also exist between Sb and Zn, and Ag and Cu. The concentrations of the metals in the bottom sediments decrease southwards and northwards from a locality close to a source of industrial waste. 相似文献
112.
The rates of formaldehyde photodecomposition into hydrogen and formyl radicals and hydrogen and carbon monoxide molecules in sunlightirradiated atmospheres have been estimated from extinction data and photochemical results. These data should prove useful in the development of models for the chemical changes that take place in the polluted atmosphere. 相似文献
113.
114.
C A Calvert 《Veterinary Clinics of North America: Small Animal Practice》1991,21(5):919-930
Few studies have been conducted that focus on survival as the end point of medical therapy of CHF. No vigorous studies have been conducted in dogs. It is generally accepted that diuretic therapy is an essential component of the therapy of CHF in cardiomyopathic dogs. Significant symptomatic improvement is afforded by diuretics, and acute death may be prevented. In this context diuretics can be said to improve survival. However, diuretics do not alter the natural progression of cardiomyopathy and in this context do not favorably influence long-term survival. Digitalis glycosides have been shown in humans to improve various parameters of CHF in a subset of patients with either atrial fibrillation or third heart sounds. In dogs, these gallop heart rhythms due to third heart sounds are usually associated with myocardial failure due to dilated cardiomyopathy. In spite of symptomatic improvement, no study has demonstrated an unequivocal favorable effect of digoxin on survival of patients with dilated cardiomyopathy. Likewise, there is no convincing evidence of an adverse effect on survival. Newer, powerful inotropes, such as milrinone, often demonstrate impressive short-term improvements in left ventricular function, clinical signs, and exercise tolerance in patients with CHF. However, their long-term benefits are much less impressive, they are arrhythmogenic, and they have not been shown to prolong survival. In fact, long-term milrinone therapy in humans has had an unfavorable influence on mortality. Vasodilators offer the potential advantage of increasing left ventricular performance without an associated increase in myocardial oxygen demand and cardiac rhythm disturbances. The only vigorous survival study that unequivocally demonstrated improved survival of patients with advanced CHF due to myocardial failure, including dilated cardiomyopathy, was the Consensus Trial. Survival of patients receiving enalapril was significantly better than those receiving placebo. In fact, the trial was stopped prematurely by the ethical review committee when it became obvious that the results favored the enalapril group. Although the use of beta-adrenergic blocking drugs in cardiomyopathic patients with CHF is controversial and associated with a risk of short-term deterioration of left ventricular function, their use in human medicine is gaining acceptance. Although hemodynamic and clinical evidence of improvement has been demonstrated along with withdrawal-associated deterioration, the only study purporting a beneficial effect on survival used retrospective controls.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
115.
A lupinosis-associated myopathy occurred in 26 of 48 sheep given a crude toxic extract of Phomopsis leptostromiformis, and in 18 of 34 sheep that grazed a toxic lupin stubble. Treatment with selenium or alpha-tocopherol alone neither prevented nor cured the myopathy, but selenium and alpha-tocopherol together may have been partially effective. Among the group of 48 intoxicated sheep, those with myopathy had a significantly lower mean terminal concentration of alpha-tocopherol in their livers than those with no myopathy. There was no relationship between the severity of liver injury and the occurrence of the myopathy. It was considered that this lupinosis-associated myopathy may have a similar pathogenesis to nutritional myopathy. Data on plasma creatine phosphokinase and erythrocyte glutathione peroxidase activities, plasma alpha-tocopherol concentrations and terminal tissue concentrations of selenium and alpha-tocopherol are presented. 相似文献
116.
117.
Analyses of predated butterflies on the forest floor at five monarch overwintering sites in Mexico and observations of birds foraging in mixed flocks indicate that individual birds of several species have learned to penetrate the monarch's cardenolide-based chemical defense. Predation is inversely proportional to colony size and appears to be one evolutionary explanation of the dense aggregations. 相似文献
118.
119.
J.D. Thomason T.L. Fallaw K.P. Carmichael M.A. Radlinsky C.A. Calvert 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2009,23(1):39-42
Background: Calcium channel blocking drugs, usually nifedipine and less often amlodipine, have been reported to cause gingival hyperplasia (GH) in humans.
Hypothesis: Amlodipine, a dihydropyridine calcium channel blocking drug, can cause GH when administered chronically to older small dogs with degenerative valvular disease.
Animals Studied: From January 2004 to May 2008, 82 client-owned dogs with degenerative valvular disease and left atrial dilatation were treated with amlodipine in combination with spironolactone and enalapril and followed for >6 months.
Methods: Retrospective study. A chronological observation of GH in 2 dogs treated with amlodipine in 2004 and 2006 prompted the study. Patient histories and medical records of each dog treated with amlodipine for degenerative valvular disease from January 2004 to May 2008 were reviewed.
Results: GH was observed by clients and the authors in 7 of 82 (8.5%) dogs. Histologic confirmation of the diagnosis was made in 2 dogs. The minimum duration of treatment before diagnosis of GH was 5 months. GH began to resolve within 2 weeks of discontinuing amlodipine and resolution was complete within 6 months. Amlodipine administration was reinstituted in 1 dog in which GH had resolved, and GH reoccurred within 4 months.
Conclusion and Clinical Importance: Long-term administration of amlodipine to dogs with degenerative valvular disease may cause GH in a small percentage of patients. GH resolves quickly after withdrawal of amlodipine treatment. 相似文献
Hypothesis: Amlodipine, a dihydropyridine calcium channel blocking drug, can cause GH when administered chronically to older small dogs with degenerative valvular disease.
Animals Studied: From January 2004 to May 2008, 82 client-owned dogs with degenerative valvular disease and left atrial dilatation were treated with amlodipine in combination with spironolactone and enalapril and followed for >6 months.
Methods: Retrospective study. A chronological observation of GH in 2 dogs treated with amlodipine in 2004 and 2006 prompted the study. Patient histories and medical records of each dog treated with amlodipine for degenerative valvular disease from January 2004 to May 2008 were reviewed.
Results: GH was observed by clients and the authors in 7 of 82 (8.5%) dogs. Histologic confirmation of the diagnosis was made in 2 dogs. The minimum duration of treatment before diagnosis of GH was 5 months. GH began to resolve within 2 weeks of discontinuing amlodipine and resolution was complete within 6 months. Amlodipine administration was reinstituted in 1 dog in which GH had resolved, and GH reoccurred within 4 months.
Conclusion and Clinical Importance: Long-term administration of amlodipine to dogs with degenerative valvular disease may cause GH in a small percentage of patients. GH resolves quickly after withdrawal of amlodipine treatment. 相似文献
120.
Y.C. Li P.J. Stoffella A.K. Alva D.V. Calvert D.A. Graetz 《Compost science & utilization》2013,21(2):63-67
Compost amendment to agricultural soils has been reported to reduce disease incidence, conserve soil moisture, control weeds, or improve soil fertility. Application rate and placement of compost largely depends on the proposed beneficial effects and the rate may vary from 25 to 250 Mg ha?1 (N content up to 4 percent). Application of high rates of compost with high N or P levels may result in excessive leaching of nitrate, ammonium, and phosphate into the groundwater. Leaching could be a serious concern on the east coast of Florida with its inherent high annual rainfall, sandy soils and shallow water table. In this study, five composts (sugarcane filtercake, biosolids, and mixtures of municipal solid wastes and biosolids) were applied on the surface of an Oldsmar sand soil (in 7.5 cm diameter leaching columns) at 100 Mg ha?1 rate and leached with deionized water (300 ml day?1, for five days; equivalent to 34 cm rainfall). The concentrations of NO3-N, NH4-N, and PO4-P in leachate reached as high as 246, 29, and 7 mg L?1, respectively. The amount of N and P leached accounted for 3.3-15.8 percent of total N and 0.2-2.8 percent of total P in the compost. The leaching peaks of NO3-N occurred following the application of only 300-400 ml water (equivalent to 6.8-9.1 cm rainfall). 相似文献