全文获取类型
收费全文 | 2324篇 |
免费 | 32篇 |
国内免费 | 1篇 |
专业分类
林业 | 60篇 |
农学 | 53篇 |
基础科学 | 5篇 |
252篇 | |
综合类 | 491篇 |
农作物 | 55篇 |
水产渔业 | 100篇 |
畜牧兽医 | 1227篇 |
园艺 | 23篇 |
植物保护 | 91篇 |
出版年
2021年 | 24篇 |
2020年 | 32篇 |
2019年 | 34篇 |
2018年 | 27篇 |
2017年 | 23篇 |
2016年 | 24篇 |
2015年 | 27篇 |
2014年 | 36篇 |
2013年 | 83篇 |
2012年 | 57篇 |
2011年 | 98篇 |
2010年 | 41篇 |
2009年 | 43篇 |
2008年 | 77篇 |
2007年 | 60篇 |
2006年 | 81篇 |
2005年 | 65篇 |
2004年 | 75篇 |
2003年 | 64篇 |
2002年 | 51篇 |
2001年 | 47篇 |
2000年 | 64篇 |
1999年 | 48篇 |
1998年 | 21篇 |
1997年 | 26篇 |
1995年 | 19篇 |
1994年 | 38篇 |
1993年 | 57篇 |
1992年 | 52篇 |
1991年 | 56篇 |
1990年 | 59篇 |
1989年 | 56篇 |
1988年 | 48篇 |
1987年 | 39篇 |
1986年 | 54篇 |
1985年 | 40篇 |
1984年 | 29篇 |
1983年 | 28篇 |
1982年 | 21篇 |
1981年 | 30篇 |
1979年 | 38篇 |
1978年 | 23篇 |
1977年 | 18篇 |
1975年 | 25篇 |
1974年 | 19篇 |
1973年 | 26篇 |
1972年 | 29篇 |
1971年 | 37篇 |
1970年 | 26篇 |
1969年 | 30篇 |
排序方式: 共有2357条查询结果,搜索用时 0 毫秒
91.
C C Chamberlain H A Fribourg K M Barth J H Felts J M Anderson 《Journal of animal science》1971,33(1):161-166
92.
Sánchez-Patán F Bartolomé B Martín-Alvarez PJ Anderson M Howell A Monagas M 《Journal of agricultural and food chemistry》2012,60(13):3396-3408
Cranberry (Vaccinium macrocarpon) products have been widely recommended in traditional American medicine for the treatment of urinary tract infection (UTI). A total of 19 different commercial cranberry products from American and European markets have been analyzed by different global phenolic methods and by UPLC-DAD-ESI-TQ MS. In addition, in vitro antioxidant capacity and uropathogenic bacterial antiadhesion activity tests have been performed. Results revealed that products found in the market widely differed in their phenolic content and distribution, including products completely devoid of flavan-3-ols to highly purified ones, either in A-type proanthocyanidins (PACs) or in anthocyanins. The product presentation form and polyphenolic profile widely affected the antiadhesion activity, ranging from a negative (nulel) effect to a MIC = 0.5 mg/mL for cranberry powders and a MIC=112 mg/mL for gel capsule samples. Only 4 of 19 products would provide the recommended dose of intake of 36 mg total PACs/day. Of most importance was the fact that this dose would actually provide as low as 0.00 and up to 205 μg/g of procyanidin A2, indicating the lack of product standardization and incongruence between global and individual compound analysis. 相似文献
93.
94.
95.
Lance F. Karcher DVM Stephen G. Dill DVM Wayne I. Anderson DVM PhD John M. King DVM PhD 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1990,4(5):247-253
Moderate to severe ulcerative colitis of the right dorsal colon was diagnosed by necropsy or by exploratory celiotomy and biopsy in 13 horses with a primary clinical complaint of either colic, diarrhea, or weight loss. Clinical signs varied from acute fulminating diarrhea (possibly with fever), colic, dehydration, endotoxic shock and death, to a chronic condition manifested by mild intermittent colic up to several months in duration, and weight loss with or without mild diarrhea. In a large percentage of the horses, those affected had been hypovolemic and received nonsteroidal anti-inflammatory drugs (NSAID) or had received inappropriately high doses of phenylbutazone before the onset of illness. Experimental treatment of two horses with high doses of a phenylbutazone oral paste preparation (6 gm once daily for 5 days) and limitation of their water intake to approximately one half of maintenance requirement (for 5 days) resulted in reproduction of ulcerative colitis involving only the right dorsal colon, which was apparent at necropsy examination 11 and 15 days after initiation of drug use. It was concluded that localized ulcerative lesions in the right dorsal colon may be a previously unreported manifestation of toxicity due to the administration of NSAID. 相似文献
96.
97.
98.
99.
Flavonoid profiles of 12 zoysiagrass (Zoysia spp.) cultivars sampled six times in 1998 were correlated to fall armyworm (Spodoptera frugiperda J. E. Smith) larval weights and survival on replicated field-grown plant material and analyzed to determine genetic and seasonal variations of flavonoids among zoysiagrass cultivars. From multiple regression analyses and correlations, flavonoid peak 10 (luteolin-glucoside) had the greatest positive association with average fall armyworm weight; however, resistance appeared to be correlated with a number of other flavonoids. The flavonoid profiles of cultivars subjected to clustering procedures showed consistent genetic variability for five of six samplings and was used to genotype 23 cultivars. The dendrogram supported the results of the FASTCLUS procedure in clustering certain genotypes such as fall armyworm-resistant Cavalier and Zeon together, as well as J-36 and Meyer. Flavonoid evaluations measure genetic relatedness among cultivars and could be used for selective breeding of resistance to fall armyworm. 相似文献
100.
A. Bytnerowicz S. Godzik M. Poth I. Anderson J. Szdzuj C. Tobias S. Macko P. Kubiesa T. Staszewski M. Fenn 《Water, air, and soil pollution》1999,116(1-2):141-150
For the first time concentrations of trace nitrogenous (N) air pollutants, gaseous nitric acid (HNO3), nitrous acid (HNO2), ammonia (NH3), and fine particulate nitrate (NO3) and ammonium (NH4), were measured in the montane forests of southern Poland. Determinations were performed in two forest locations of the Silesian Beskid Mountains in the western range of the Carpathian Mountains, and in an industrial/urban location in Karowice, Poland. The measurements performed in summer 1997 with honeycomb denuder/filter pack systems showed elevated concentrations of the studied pollutants. These findings agree with the low carbon/nitrogen (C/N) ratios and the results of 15N analyses of soil and moss samples. High concentrations of N air pollutants help to explain previously determined high levels of NO3 and NH4 deposition to Norway spruce (Picea abies Karst.) canopies in these mountains. Ambient concentrations of sulfur dioxide (SO2) and ozone (O3) were elevated and potentially phytotoxic. Deficiencies of phosphorus (P) and magnesium (Mg) in Norway spruce foliage were found while concentrations of other nutrients were normal. 相似文献