全文获取类型
收费全文 | 1273篇 |
免费 | 44篇 |
国内免费 | 1篇 |
专业分类
林业 | 151篇 |
农学 | 26篇 |
基础科学 | 2篇 |
280篇 | |
综合类 | 145篇 |
农作物 | 43篇 |
水产渔业 | 58篇 |
畜牧兽医 | 527篇 |
园艺 | 11篇 |
植物保护 | 75篇 |
出版年
2021年 | 14篇 |
2020年 | 21篇 |
2019年 | 15篇 |
2018年 | 16篇 |
2017年 | 17篇 |
2016年 | 22篇 |
2015年 | 14篇 |
2014年 | 16篇 |
2013年 | 46篇 |
2012年 | 50篇 |
2011年 | 56篇 |
2010年 | 37篇 |
2009年 | 43篇 |
2008年 | 64篇 |
2007年 | 57篇 |
2006年 | 45篇 |
2005年 | 47篇 |
2004年 | 49篇 |
2003年 | 47篇 |
2002年 | 27篇 |
2001年 | 21篇 |
2000年 | 20篇 |
1999年 | 23篇 |
1998年 | 12篇 |
1994年 | 11篇 |
1992年 | 22篇 |
1991年 | 30篇 |
1990年 | 17篇 |
1989年 | 30篇 |
1988年 | 13篇 |
1987年 | 25篇 |
1986年 | 25篇 |
1985年 | 25篇 |
1984年 | 17篇 |
1982年 | 11篇 |
1980年 | 10篇 |
1979年 | 17篇 |
1978年 | 15篇 |
1977年 | 11篇 |
1976年 | 9篇 |
1975年 | 8篇 |
1974年 | 17篇 |
1973年 | 11篇 |
1972年 | 15篇 |
1970年 | 22篇 |
1969年 | 11篇 |
1968年 | 14篇 |
1967年 | 21篇 |
1966年 | 9篇 |
1936年 | 7篇 |
排序方式: 共有1318条查询结果,搜索用时 0 毫秒
141.
142.
143.
Reinhard Mischke 《Journal of veterinary diagnostic investigation》2003,15(6):588-591
The in vitro heparin sensitivity of 6 different commercial activated partial thromboplastin time (APTT) reagents was investigated based on artificial plasma samples prepared by addition of sodium heparin at different activities (0-1.5 IU/ml) to pooled normal canine plasma. Statistical analysis using 2-way analysis of variance was based on APTT ratios (APTT/mean APTT control). Significant differences between the APTT ratios of different APTT reagents (P < 0.00001) were found, which also depended on heparin activity (interaction between the factors; P < 0.00001). For example, mean APTT ratio at 0.7 IU/ml heparin varied between 1.2 and 2.5. The results of this study indicate that recommendations for the control of heparin therapy in dogs by APTT ratio should be reagent specific. 相似文献
144.
An overview of the circulation of the liver and of the pathogenesis of hepatic encephalopathy as a result of portal vascular anomalies is given. Clinical signs associated with portal systemic shunts are described on the basis of 16 cases, 14 dogs and 2 cats. These animals ranged in age at the time of presentation from 4 months to 7 years. The predominant abnormality observed were central nervous signs, which differed in severity. The different techniques of contrast angiography allowing demonstration of a portal systemic shunt are presented along with a discussion of the pros and cons of each. Additionally the significance of making portal venous pressure measurements prior to each angiography is also explained. In most cases mesenteric portography was chosen. Based on their location the anomalies could be categorized as intrahepatic (4 dogs) or extrahepatic (10 dogs, 2 cats). In both groups breeds of various size are represented. The extrahepatic shunts could be further described as portal-caval (n = 5), portal-phrenic (n = 4) and portal-azygos (n = 3). In five of the older animals angiography showed in addition some hepatic perfusion by the portal vein. Laboratory evaluation revealed increased resting blood ammonia concentrations (greater than 200-912 micrograms/100 ml) in all animals. Seven dogs had definitely subnormal BUN concentrations (less than 10 mg%) and ten dogs low total plasma protein levels (less than 5.4 g%). Free amino acids (24) were determined in four dogs and a lowered hepatic encephalopathy index (less than 1.64) found. Medical palliative therapy to control the clinical signs is discussed. The only effective long term therapy is, however, surgery. The shunt vessel is narrowed so that a greater volume of portal blood reaches the liver. Experience gained from the surgical therapy of 14 animals is presented. Ten of these survived well without requiring further therapy at a later time. Finally the etiology, prognosis, and differential diagnosis are summarized. 相似文献
145.
146.
147.
148.
149.
A metacercarial infestation is reported in Canadian Umbra limi and a mass infestation by trematodes in Physa sp. from the same locality. Trials made by using parasitised snails showed that both parasites are not of the same species. 相似文献
150.
Thirty canine urinary calculi, most of which had been qualitatively classified as struvite calculi, were analyzed by instrumental neutron activation analysis at the University of Missouri Research Reactor. Measurements of sodium, magnesium, aluminum, silicon, phosphorus, chloride, potassium, and calcium were possible, using a dual irradiation procedure. Magnesium was used to calculate the percentage of struvite mineral, Mg(NH4) (PO4) X 6H2O, in the calculi by making use of the stoichiometric relationship of the element magnesium to the mineral. For those calculi containing greater than 80% struvite, the mean elemental concentrations were found to be 0.12% Na, 9.35% Mg, 0.0033% Al, 12.1% P, 0.02% Cl, 0.85% K, and 2.05% Ca. A new method for determination of silicon in urinary calculi also was discussed. Two calculi were found to contain 45.0% and 37.3% silicon, and 1 mixed calculus was composed of 1.4% silicon. 相似文献