全文获取类型
收费全文 | 140430篇 |
免费 | 7905篇 |
国内免费 | 298篇 |
专业分类
林业 | 5980篇 |
农学 | 4825篇 |
基础科学 | 911篇 |
18786篇 | |
综合类 | 22382篇 |
农作物 | 5903篇 |
水产渔业 | 7370篇 |
畜牧兽医 | 70820篇 |
园艺 | 1950篇 |
植物保护 | 9706篇 |
出版年
2021年 | 1200篇 |
2020年 | 1410篇 |
2019年 | 1581篇 |
2018年 | 2319篇 |
2017年 | 2638篇 |
2016年 | 2402篇 |
2015年 | 1982篇 |
2014年 | 2543篇 |
2013年 | 5786篇 |
2012年 | 4661篇 |
2011年 | 5641篇 |
2010年 | 3590篇 |
2009年 | 3673篇 |
2008年 | 5437篇 |
2007年 | 5099篇 |
2006年 | 4742篇 |
2005年 | 4439篇 |
2004年 | 4153篇 |
2003年 | 4341篇 |
2002年 | 3935篇 |
2001年 | 4462篇 |
2000年 | 4443篇 |
1999年 | 3498篇 |
1998年 | 1520篇 |
1997年 | 1437篇 |
1996年 | 1322篇 |
1995年 | 1568篇 |
1994年 | 1397篇 |
1993年 | 1275篇 |
1992年 | 2612篇 |
1991年 | 2725篇 |
1990年 | 2629篇 |
1989年 | 2653篇 |
1988年 | 2393篇 |
1987年 | 2373篇 |
1986年 | 2444篇 |
1985年 | 2368篇 |
1984年 | 1918篇 |
1983年 | 1696篇 |
1982年 | 1168篇 |
1979年 | 1770篇 |
1978年 | 1415篇 |
1976年 | 1230篇 |
1975年 | 1311篇 |
1974年 | 1521篇 |
1973年 | 1527篇 |
1972年 | 1422篇 |
1971年 | 1324篇 |
1970年 | 1260篇 |
1969年 | 1295篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
172.
Evaluation of the long-acting somatostatin analogue Octreotide in the management of insulinoma in three dogs 总被引:1,自引:0,他引:1
K. W. Simpson R. L. Stepien C. M. Elwood A. Boswood C. R. Vaillant 《The Journal of small animal practice》1995,36(4):161-165
The response of dogs with insulinoma to surgical and medical management is variable, with the majority developing intractable hypoglycaemia. A long-acting somatostatin analogue, Octreotide (SMS 201–995; Sandostatin) has been useful in the management of hypoglycaemia in humans with insulinoma, and preliminary reports suggest a beneficial clinical response in dogs with insulinoma. The present study objectively evaluated Octreotide in the management of three dogs with immunohistochemically confirmed insulinoma. Octreotide had no benefit over placebo, and little effect on circulating glucose and insulin concentrations despite clearly detectable plasma concentrations of Octreotide. No clinical improvement was apparent in two dogs given Octreotide over a period of two and three weeks. These results contrast with the positive clinical responses noted previously and indicate that further placebo controlled, objective studies are necessary before clear statements on the treatment of insulinoma with Octreotide are made. 相似文献
173.
P I Rekwot E O Oyedipe O O Akerejola A A Voh P M Dawuda 《The British veterinary journal》1989,145(1):85-88
Twenty-one Bunaji (White Fulani, Zebu) and 21 Friesian X Bunaji cross-bred bull calves, approximately 6 months of age, were each divided after weaning into two groups and fed isocaloric rations containing 14.45% (high protein) and 8.51% (low protein) crude protein for 10 months. Serum samples were collected biweekly for 10 months and analysed for serum proteins. Age had no significant effect. The Bunaji had significantly (P less than 0.05) higher total protein, albumin, and alpha 1-globulin than Friesian X Bunaji. While there was no significant difference in body condition score between the two breeds, the Friesian X Bunaji had a significantly (P less than 0.05) higher growth rate. Animals on high protein diets had significantly (P less than 0.05) higher total protein, albumin, alpha 2-globulin, gamma-globulin and total globulin than those on low protein. However, alpha 1-globulin and beta-globulin were not significantly (P greater than 0.05) different for the two treatment groups. 相似文献
174.
Muscle biopsies were taken from the middle gluteal muscle of 28 Standardbred trotters, 3-4 years of age. The 13 horses in Group T were trained consistently from 18 months of age, whereas the 15 horses in Group UT were not exposed to any systematic training before 3 years of age. Group T horses had a lower percentage of Type IIB fibres (31%) than did Group UT horses (39%). Citrate synthase (CS) activity, representing oxidative capacity, was higher in Group T (72 mmol kg-1 min-1) than in Group UT (47 mmol kg-1 min-1). Biopsies were taken from 4 horses in each group when they were foals and then annually until 3-4 years of age. Results from this study indicate that regular training of Standardbreds from 18 months of age resulted in increased CS activity and a decrease in the percentage of Type IIB fibres. This study shows that training, not growth, is the main factor that induces a high oxidative capacity and a high Type IIA/IIB fibre ratio in muscle of Standardbred trotters. 相似文献
175.
176.
The objective of these experiments was to examine methods of modifying the fatty acid composition of bovine tissues. In the first experiment, four steers were fitted with duodenal fistulas and were assigned to four diets in a Latin square design. The steers were fed a control diet or the same diet containing 10% high-oleate partially crushed sunflower seeds, serum-coated sunflower seeds, and heat-treated, serum-coated sunflower seeds for 5 d. Samples of digesta and feces were collected on d 5. The inclusion of sunflower seeds (plain or serum-coated) in the diet increased (P less than .05) the digesta concentration of stearate. The percentage of stearate in the digesta and feces was increased (P less than .05) from 51 to 67% and from 64 to 74%, respectively, when steers were fed the untreated sunflower seed. The fecal concentration of oleate was increased (P less than .05) by dietary sunflower seeds in steers that were fed the serum-coated, unheated sunflower seeds. In a second experiment, heifers (four per group) were fed a corn-based control diet or diets containing 10% of high-oleate sunflower oil encapsulated with calcium alginate, either plain, coated with blood meal, or with blood meal integrated into the pellet. After 50 d on treatment, samples of perianal adipose tissue were obtained by biopsy. The fatty acid composition of the adipose tissue was not modified by the inclusion of the encapsulated oleate in the diet. In summary, limited ruminal bypass of sunflower seed oleate was accomplished with sunflower seed but not with encapsulated oleate. 相似文献
177.
Chickens were given daily injections of cyproterone acetate (CA) and the effects on plasma corticosterone, bodyweight, weights of the adrenals and lymphoid organs, numbers of circulating peripheral blood lymphocytes and their proliferation in the presence of lectins, concanavalin A (Con A) and phytohaemagglutinin (PHA), were investigated. Five daily doses of 10 or 30 mg CA kg-1 bodyweight each week over a three-week period caused a decrease in weight gain and a reduction in the relative weights of the bursa and thymus but not the spleen. There was a small decrease in the adrenals after treatment with 10 mg CA kg-1. When daily injections of CA were given over a seven-day period doses of 6 and 10 mg CA kg-1 bodyweight caused a significant (P less than 0.05) decrease in plasma corticosterone concentration after four days. However, after eight daily injections of CA a single injection of corticotrophin (10 iu ACTH kg-1) increased circulating corticosterone indicating CA had not completely blocked adrenal synthesis. CA had no effect on numbers of circulating peripheral blood lymphocytes or their ability to proliferate in the presence of Con A or PHA. The results indicate that CA is effective in lowering circulating corticosterone in the fowl but this did not affect the numbers or responsiveness of peripheral blood lymphocytes. 相似文献
178.
179.
The relationship between the levels of CO and airborne Pb was evaluated against conditions of traffic flow, ambient air temperature and the ventilation rates in 3 underground car parks. During the study period significant variations were noted in the levels of the pollutants in each of the car parks which frequently exceeded the proposed Malaysian Air Quality Standard of 0.7 μg m?3Pb and 9 μg L?1 (8 hr average) CO for indoor environs. High correlation coefficient values were obtained between the levels of CO and traffic flow and Pb and traffic flow. High traffic flow also increased the mean air temperature inside the car parks. Reductions in the ventilation rates in the car parks caused an almost two-fold increase in the level of CO and vice versa. A simple mathematical model depicting the CO concentrations in relation to other parameters was formulated. 相似文献
180.
A tumor of the third eyelid gland was diagnosed in a 13 year old female Chihuahua. Histopathology of the excised tissue revealed an apocrine adnexoma with squamous metaplasia. The literature regarding prolapse and tumors of the third eyelid gland was reviewed. No case with similar morphology to this tumor was described to our knowledge. 相似文献