全文获取类型
收费全文 | 5955篇 |
免费 | 385篇 |
国内免费 | 740篇 |
专业分类
林业 | 350篇 |
农学 | 681篇 |
基础科学 | 322篇 |
617篇 | |
综合类 | 2477篇 |
农作物 | 448篇 |
水产渔业 | 166篇 |
畜牧兽医 | 631篇 |
园艺 | 178篇 |
植物保护 | 1210篇 |
出版年
2024年 | 31篇 |
2023年 | 142篇 |
2022年 | 193篇 |
2021年 | 241篇 |
2020年 | 247篇 |
2019年 | 312篇 |
2018年 | 188篇 |
2017年 | 321篇 |
2016年 | 395篇 |
2015年 | 311篇 |
2014年 | 446篇 |
2013年 | 319篇 |
2012年 | 506篇 |
2011年 | 491篇 |
2010年 | 407篇 |
2009年 | 346篇 |
2008年 | 267篇 |
2007年 | 328篇 |
2006年 | 269篇 |
2005年 | 219篇 |
2004年 | 158篇 |
2003年 | 152篇 |
2002年 | 106篇 |
2001年 | 98篇 |
2000年 | 79篇 |
1999年 | 69篇 |
1998年 | 67篇 |
1997年 | 57篇 |
1996年 | 56篇 |
1995年 | 44篇 |
1994年 | 28篇 |
1993年 | 22篇 |
1992年 | 36篇 |
1991年 | 34篇 |
1990年 | 18篇 |
1989年 | 21篇 |
1988年 | 12篇 |
1987年 | 16篇 |
1986年 | 7篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1963年 | 1篇 |
1962年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有7080条查询结果,搜索用时 31 毫秒
1.
A disease causing the decline of papaya (Carica papaya) plants was noticed in the Jordan Valley in 1982. The disease caused severe yellowing of the upper leaves and dieback of the apex. The disease was not transmissible mechanically and continued efforts to associate viruses and viroids have so far been unsuccessful. Epidemiological observations suggested that the disease is airborne and probably caused by a mollicute. In order to test this hypothesis, plots were covered by an insect-proof net and with white nets providing 15, 30 and 50% shade. The 30%, 50% and insect-proof nettings provided complete protection, and the 15% netting reduced disease incidence to <2%, compared with>37% in the uncovered control plot. Spraying plants at weekly intervals with a commercial whitewash solution was also found to be effective in reducing disease incidence. The advantages of using a range of netting field treatments as a simple means for obtaining information on the epidemiological nature of a new disease are described. 相似文献
2.
3.
4.
试验采用单因素随机区组设计,叶面喷施肥料的施肥方法,应用方差分析和多重比较分析试验数据,从而筛选出小菊最佳的营养元素配方。试验从不同叶面肥料在小菊上的筛选与应用研究的试验结果得到:小菊对肥料具有较强的选择性:三高灵的施用能够增加小菊的开花数量和鲜叶片叶绿素的含量;宝力丰的施用能提高小菊单株的干物重;OPAL的施用能延长小菊开花的花期。 相似文献
5.
3种农药的微核效应研究 总被引:6,自引:0,他引:6
运用蚕豆根尖微核技术研究3种农药(甲胺磷、甲基硫菌灵和盐酸吗啉胍)在不同浓度下的诱变效应。结果表明,3种农药诱发蚕豆根尖细胞微核率与对照组相比均有不同程度的上升(P<0.05或P<0.01),农药浓度与微核率呈剂量-效应关系,盐酸吗啉胍的诱变效应大于其他2种农药。 相似文献
6.
7.
采用种子处理方法可显著提高种子发芽率、降低发病率;其中以药剂浸种效果最好;药剂处理以多菌灵+福美双和多菌灵两个配方最佳。 相似文献
8.
According to the requirements of the conversion of farmland to forests project (CFFP), we investigated the vegetation factors
and environmental factors from more than 6,105 sub-compartments in Liangcheng County, Inner Mongolia by using the Matlab,
analytic hierarchy process (AHP), and the hierarchical cluster method (HCM). The site conditions were classified quantitatively.
The results show that CFFP at this site comprises five site-type groups and 19 site types. A quantitative site classification
system method has been established in this paper.
__________
Translated from Journal of Beijing Forestry University, 2005, 27(6) [译自: 北京林业大学学报, 2005, 27(6)] 相似文献
9.
M. Bonierbale R. Plaisted S. Tanksley 《European journal of plant pathology / European Foundation for Plant Pathology》1992,98(Z2):211-214
Introgression of trichome-mediated insect resistance from the wild speciesSolanum berthaultii has become a major focus of the potato improvement program at Cornell University during the past twelve years. Several quantitative characters are involved in this resistance which is effective against a wide range of pest types. Correlative biochemical assays have been developed to assay specific components of the resistance, and the effects of the resistance on the target pests have been studied. Quantitative laboratory assays and specific measurements of insect behavior and biology have increased the precision of selection and enable the investigation of the genetic control of the resistance.We are currently using restriction fragment length polymorphisms (RFLPs) for genetic mapping of factors controlling the trichome traits fromS. berthaultii. Backcrosses to both the wild and the cultivated species parents have been evaluated for phenotypes contributing to the resistance mechanism, including trichome density, sucrose ester and polyphenol oxidase production by the trichomes, and the enzymatic browning reaction responsible for insect entrapment. Genetic maps are being developed for these progenies, using RFLP markers previously mapped in potato. Field and greenhouse trials under insect infestations are also being conducted with the mapping progeny. Our goal is to locate genes responsible for quantitative insect resistance by correlating RFLP variation at mapped loci with the trichome phenotypes and insect resistance. Genetic markers for these traits will be useful in transfer of the effective wild chromosomal segments into and among tetraploid potatoes, and for a better understanding of the resistance mechanism. 相似文献
10.