全文获取类型
收费全文 | 20270篇 |
免费 | 185篇 |
国内免费 | 436篇 |
专业分类
林业 | 4118篇 |
农学 | 1866篇 |
基础科学 | 456篇 |
3426篇 | |
综合类 | 1800篇 |
农作物 | 2276篇 |
水产渔业 | 1934篇 |
畜牧兽医 | 1628篇 |
园艺 | 1248篇 |
植物保护 | 2139篇 |
出版年
2024年 | 7篇 |
2023年 | 25篇 |
2022年 | 88篇 |
2021年 | 134篇 |
2020年 | 110篇 |
2019年 | 115篇 |
2018年 | 2812篇 |
2017年 | 2814篇 |
2016年 | 1302篇 |
2015年 | 210篇 |
2014年 | 167篇 |
2013年 | 182篇 |
2012年 | 1052篇 |
2011年 | 2363篇 |
2010年 | 2333篇 |
2009年 | 1475篇 |
2008年 | 1500篇 |
2007年 | 1774篇 |
2006年 | 248篇 |
2005年 | 316篇 |
2004年 | 191篇 |
2003年 | 234篇 |
2002年 | 147篇 |
2001年 | 86篇 |
2000年 | 147篇 |
1999年 | 144篇 |
1998年 | 130篇 |
1997年 | 100篇 |
1996年 | 86篇 |
1995年 | 89篇 |
1994年 | 70篇 |
1993年 | 94篇 |
1992年 | 71篇 |
1991年 | 50篇 |
1990年 | 64篇 |
1989年 | 40篇 |
1988年 | 39篇 |
1987年 | 22篇 |
1986年 | 16篇 |
1985年 | 3篇 |
1984年 | 8篇 |
1983年 | 5篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1977年 | 4篇 |
1972年 | 1篇 |
1969年 | 1篇 |
1968年 | 4篇 |
1967年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
21.
本研究选用40头胎次、产奶量、泌乳期相近的中国荷斯坦奶牛随机分成4组(n=10),试验组奶牛日粮中分别添加45、60和75mg/kg大豆黄酮,在试验前及试验开始后第10天、第20天和第30天颈静脉采血,测定4组奶牛血清钙、磷和葡萄糖水平。结果表明:与对照组相比较,试验1组中血清钙、磷和葡萄糖变化均不显著(P>0.05);试验2组仅血清钙在第30天时显著高于对照组(P<0.05);试验3组第10天和20天时血清钙水平显著高于对照组(P<0.05),第30天时血清钙水平极显著高于对照组(P<0.01),而血糖水平仅第30天显著高于对照组(P<0.05)。 相似文献
22.
Shohei MATSUURA Shigeru HOSHINO Hideaki HAYASHI Tetsuyuki KOHGUCHI Kyoji HAGIWARA Toshihiro OMURA 《Journal of General Plant Pathology》2002,68(1):99-102
DAS-ELISA proved to be reliable enough to detect a latent infection by Tomato spotted wilt virus (TSWV) in asymptomatic stock plants of chrysanthemum. A high density of Frankliniella occidentalis, the predominant vector, in the presence of latently infected stock plants resulted in a high incidence of disease in the chrysanthemum
production field. The incidence of disease was low when the vector thrips were not abundant in spite of the presence of latently
infected stock plants. These results suggest that an infestation of the vector thrips causes severe secondary spread of TSWV
originating from latently infected stock plants in chrysanthemum production fields.
Received 27 July 2001/ Accepted in revised form 27 November 2001 相似文献
23.
24.
25.
26.
Eiji Tanaka Chihiro Tanaka Atsushi Ishihara Yasumasa Kuwahara Mitsuya Tsuda 《Journal of General Plant Pathology》2003,69(1):1-6
Aciculosporium take (Ascomycota; Clavicipitaceae) is a causal agent of witches' broom of
bamboo plants. The symptoms of this disease are believed to be induced by plant
hormones, particularly auxins. Indole-3-acetic acid (IAA) was identified in
cultures of this fungus in an l-tryptophan-supplemented liquid medium.
IAA production was confirmed on 30 isolates of A. take from various
hosts and locations at levels up to 1 mg/l. The biosynthetic pathway of
IAA in A. take culture was examined by analyzing intermediate products
and by feeding experiments. The results showed that the indole-3-pyruvic acid
pathway (l-tryptophan → indole-3-pyruvic acid → indole
acetaldehyde → IAA) was the dominant pathway in A. take.
Received: June 3, 2002 / Accepted: July 25, 2002 相似文献
27.
Hiromitsu Furuya Tsutomu Matsumoto Shin-ichi Fuji Hideki Naito 《Journal of General Plant Pathology》2003,69(2):115-119
Rice seedling growth, estimated by plant height and root development and discoloration, was better in pasteurized soil than
in unpasteurized soil obtained from a flooded rice field. Rice seedlings also grew better in sterilized soil modified by adding
roots harvested from the pasteurized soil than in soil modified by adding roots harvested from the unpasteurized soil. The
results demonstrate that seedling growth in the rice field soil was inhibited by soil microorganisms, even though no typical
symptoms such as seedling blight or damping-off appeared. Pythium aristosporum is suggested to be involved in the inhibition. Thus, it appears that inconspicuous restraint of rice seedling growth could
occur in soils of rice paddy fields.
Received: May 20, 2002 / Accepted: October 16, 2002
Acknowledgments The authors thank Dr. T. Ichitani, former professor at Osaka Prefectural University, for providing an isolate of Pythium aristosporum for comparison, and Mr. Mitsuaki Sato of Akita Prefectural College of Agriculture for technical assistance. 相似文献
28.
29.
‘禅寺丸’甜柿2n花粉形成机制的研究 总被引:13,自引:1,他引:13
以2n花粉发生频率较高的甜柿品种‘禅寺丸’为试材,研究影响2n花粉形成的减数分裂行为。结果表明:2n花粉形成受融合纺锤体(fused spindles),八字形纺锤体(triangle spindles)及后期Ⅱ染色单体不正常分离(abnormal disorientation of sister chromatid)3种减数分裂行为控制;融合纺锤体及八字形纺锤体形成的2n花粉占2n花粉总数的94.8%,在遗传上等同于FDR(first division restitution,第1次分裂重组)型配子;由姊妹染色单体不正常分离形成的2n花粉在遗传上等同于SDR (second division restitution,第2次分裂重组)型配子。甜柿2n花粉绝大多数为FDR型,因而在倍性育种中有重要的应用价值。 相似文献
30.