全文获取类型
收费全文 | 248324篇 |
免费 | 14797篇 |
国内免费 | 658篇 |
专业分类
林业 | 23314篇 |
农学 | 13941篇 |
基础科学 | 2942篇 |
41890篇 | |
综合类 | 24690篇 |
农作物 | 17116篇 |
水产渔业 | 16606篇 |
畜牧兽医 | 93741篇 |
园艺 | 6262篇 |
植物保护 | 23277篇 |
出版年
2021年 | 2424篇 |
2020年 | 2829篇 |
2019年 | 3613篇 |
2018年 | 3843篇 |
2017年 | 4156篇 |
2016年 | 4666篇 |
2015年 | 4255篇 |
2014年 | 5633篇 |
2013年 | 16194篇 |
2012年 | 5742篇 |
2011年 | 7530篇 |
2010年 | 7132篇 |
2009年 | 7729篇 |
2008年 | 6968篇 |
2007年 | 6073篇 |
2006年 | 6756篇 |
2005年 | 5955篇 |
2004年 | 5870篇 |
2003年 | 5649篇 |
2002年 | 5064篇 |
2001年 | 5582篇 |
2000年 | 5300篇 |
1999年 | 5093篇 |
1998年 | 4100篇 |
1997年 | 4174篇 |
1996年 | 3857篇 |
1995年 | 4441篇 |
1994年 | 3825篇 |
1993年 | 3534篇 |
1992年 | 4101篇 |
1991年 | 4294篇 |
1990年 | 4064篇 |
1989年 | 4054篇 |
1988年 | 3625篇 |
1987年 | 3664篇 |
1986年 | 3539篇 |
1985年 | 3875篇 |
1984年 | 3603篇 |
1983年 | 3449篇 |
1982年 | 2861篇 |
1981年 | 2762篇 |
1980年 | 2740篇 |
1979年 | 3211篇 |
1978年 | 2854篇 |
1977年 | 2678篇 |
1976年 | 2489篇 |
1974年 | 2653篇 |
1973年 | 2636篇 |
1972年 | 2420篇 |
1971年 | 2380篇 |
排序方式: 共有10000条查询结果,搜索用时 478 毫秒
201.
202.
T Nishita M Sakomoto T Ikeda H Amasaki M Shino 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2001,63(10):1147-1149
Salivary or secreted carbonic anhydrase (CA), which constitutes a new class of CA, designated CA-VI, was isolated. Swine CA-VI purified from swine saliva by inhibitor-affinity chromatography and ion exchange chromatography had a specific activity of 5,468 units/mg. The molecular weight was 250,000, as determined by gel filtration under non-denaturing conditions, and the subunit molecular weight was found to be 37,000 by sodium dodecyl sulfate polyacrylamide gel electrophoresis, indicating that swine CA-VI consists of 7 subunits. The treatment of the enzyme with endo-N-acetylglucosaminidase F reduced its subunit molecular weight from 37,000 to 35,000 and 32,000. We raised a rabbit antibody against purfied swine CA-VI. Double immunodiffusion showed that anti-swine CA-VI serum reacted with swine CA-VI and swine saliva, but not with hemolysate (containing CA-I and CA-Il) or muscle extracts (containing CA-III). The concentration of CA-VI in swine saliva, measured using single radial immunodiffusion, was 0.027 +/- 0.017 mg/mg total protein. 相似文献
203.
204.
205.
Lactate Kinetics in veterinary Critical Care: A Review 总被引:3,自引:0,他引:3
Michael S. Lagutchik DVM Gregory K. Ogilvie DVM Wayne E. Wingfield MS DVM Timothy B. Hackett DVM MS 《Journal of Veterinary Emergency and Critical Care》1996,6(2):81-95.
Elevation in blood lactate concentration, with or without accompanying metabolic acidosis, is a hallmark finding in patients with circulatory compromise, and is also consistently noted in other conditions affecting critically ill or injured individuals. Little is reported in a veterinary literature regarding lactate measurement in the emergency and critical care setting, despite impressive reports of the clinical usefulness of lactate measurement in people. The purpose of this article is to review lactate kinetics and the clinical utility of lactate measurement. Limitations to lactate evaluation will also be discussed. 相似文献
206.
Results are given of a survey on the occurrence of pathotypes (races) of Synchytrium endobioticum (potato wart) in both parts of re-unified Germany. An assortment of six differential cultivars appears to be sufficient to distinguish between the seven presently important German wart pathotypes. A total of ten pathotypes was recorded. Two West and two East German pathotypes seem to be identical, based on the results obtained with presently available cultivars. In contrast to pathotype 1 (common race) which prior to 1945 was distributed over the whole German territory, the 'new' pathotypes seem to prefer the central and south German mountain areas. 相似文献
207.
合成了14个含有 N-莰-2-基的磷酰胺和硫代磷酰胺类化合物,用红外、核磁及元素分析确定其结构,并探讨了~(31)Pδ值的规律性变化。初步生物试验表明,磷酰胺类化合物对水稻发芽具有明显的抑制作用,其中化合物Ⅱ1的活性大于对照药剂抗倒胺但低于多效唑。 相似文献
208.
209.
210.
Abstract. In field and laboratory experiments the conditioner‘Agri-SC’has shown improvements in the structure of loamy sand soils in east Shropshire, UK. It resulted in statistically significant decreases in soil bulk density values and increases in soil porosity and aggregate stability. Further experiments are in progress on both loamy sand and silt loam soils. 相似文献