全文获取类型
收费全文 | 2578篇 |
免费 | 161篇 |
国内免费 | 143篇 |
专业分类
林业 | 433篇 |
农学 | 337篇 |
基础科学 | 3篇 |
134篇 | |
综合类 | 953篇 |
农作物 | 167篇 |
水产渔业 | 157篇 |
畜牧兽医 | 418篇 |
园艺 | 142篇 |
植物保护 | 138篇 |
出版年
2024年 | 10篇 |
2023年 | 26篇 |
2022年 | 61篇 |
2021年 | 63篇 |
2020年 | 94篇 |
2019年 | 87篇 |
2018年 | 66篇 |
2017年 | 80篇 |
2016年 | 92篇 |
2015年 | 98篇 |
2014年 | 132篇 |
2013年 | 164篇 |
2012年 | 184篇 |
2011年 | 175篇 |
2010年 | 144篇 |
2009年 | 149篇 |
2008年 | 125篇 |
2007年 | 167篇 |
2006年 | 139篇 |
2005年 | 105篇 |
2004年 | 95篇 |
2003年 | 67篇 |
2002年 | 52篇 |
2001年 | 66篇 |
2000年 | 46篇 |
1999年 | 38篇 |
1998年 | 45篇 |
1997年 | 37篇 |
1996年 | 38篇 |
1995年 | 26篇 |
1994年 | 32篇 |
1993年 | 21篇 |
1992年 | 22篇 |
1991年 | 29篇 |
1990年 | 19篇 |
1989年 | 21篇 |
1988年 | 17篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1984年 | 13篇 |
1982年 | 7篇 |
1981年 | 3篇 |
1980年 | 6篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1975年 | 1篇 |
1963年 | 1篇 |
1956年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有2882条查询结果,搜索用时 307 毫秒
81.
长江野生中华绒螯蟹育苗性能的初步研究 总被引:1,自引:0,他引:1
2011年11月,从安徽省无为县选择野生长江中华绒螯蟹亲本1 388只,到江苏省如东县进行天然海水生态育苗,其中雄蟹350只,总重80.05 kg;雌蟹1 038只,总重194.05 kg。在面积为2.5亩的池塘中,进行对比育苗试验,繁育盐度保持在19‰~26‰,pH变化范围在8.28~8.90,比较野生长江中华绒螯蟹与普通蟹之间繁育性状的差异。结果表明,野生亲本的体重和卵重均高于普通亲本,差异极显著;野生亲本与普通亲本的成熟系数和相对繁殖力差异不显著;野生蟹产卵率(52.85%)高于普通蟹产卵率(30.91%);野生蟹亲本组幼体发育较普通幼体发育为快,幼体个体较大,共产大眼幼体苗6.5 kg,大眼幼体规格137 848个.kg-1,平均125.3只.g-1;普通亲本组大眼幼体共产23 kg,规格为156 468个.kg-1,平均156.5只.g-1。 相似文献
82.
83.
浙西南野生观赏树木资源多样性 总被引:7,自引:0,他引:7
在对浙江省丽水市野生观赏树木资源调查研究的基础上,评价和分析了浙西南野生观赏树木种类的多样性,观赏特性的多样性,生长类型的多样性和园林用途的多样性,调查发现浙西南丽水市野生观赏树木资源丰富,全市共有野生观赏树种405种,根据观赏特性划分,有观花树木138种,观果树木108种,观姿树木76种,观叶树木72种,观枝干11种;按生长类型划分,有乔木155种,灌木196种,藤本41种,竹类1种,这些野生观赏树木可以在园林绿化中作为行道树或庭荫树栽培,也可作观赏树在园林中孤植或片植,用作垂直绿化和制作桩景,就浙西南野生观赏树木资源的合理开发和利用提出了建议。表1参3。 相似文献
84.
湖北四湖地区的野菜资源及其开发利用 总被引:6,自引:0,他引:6
依据湖北四湖地区的地理位置、地貌和气候等自然条件,将区内野菜的生境分为湖泊、塘渊沟渠、沼泽、河流洲滩、村落和田土等生态系统;以二单元分类方法记述了四湖地区34科59属的野菜79种;阐述了区内重要野菜的种类、野菜蕴藏量、利用价值和开发利用现状;提出了开展四湖地区重点野菜资源调查研究,制订野菜资源的保护措施,建立野菜商品生产基地及野菜人工驯化栽培等开发利用对策。 相似文献
85.
Dayun Sun Wenxiang Wang Xiaoyun Xin Liming Cao Xuejun Sun Zejun Hu Ling Jiang Shiqing Dong Yahui Liu Jinshui Yang Xiaojin Luo 《Plant Breeding》2019,138(2):163-173
Heading date is one of the most important traits in rice and regulated by multiple genes. Common wild rice is the ancestor of Asian cultivated rice and harbours abundant genetic diversity. To use wild rice resource in rice breeding, a set of 154 introgression lines (ILs) covering 93% of the genome of Jinghong common wild rice was constructed in the background 'Teqing', using 208 simple sequence repeat markers evenly distributed on 12 chromosomes. Among the ILs, the line JIL64 displayed late heading independent of photoperiod. Genetic analysis using the two F2 populations crossed ''Teqing'/JIL64 and JIL64/'Teqing' revealed that late flowering was controlled by a recessive gene on chromosome 8 (designated early heading date 8, ehd8), and ehd8 was fine mapped to the 50‐kb region flanked by markers RM22221 and 64Indel4. Sequencing and qRT‐PCR demonstrated that LOC_Os08g01410 and LOC_Os08g01420 were deleted in JIL64 and may be associated with the late heading of Jinghong common wild rice. These findings lay a practical foundation for characterizing ehd8, and the ILs help to mine genes from Jinghong common wild rice. 相似文献
86.
Wild radish (Raphanus raphanistrum) has developed introgressed populations after hybridization with its cultivated counterpart (R. sativus) in California. Hybridization with various Brassica and Sinapis species is also possible. To determine if hybridization is responsible of the genetic diversity of European populations, six wild radish populations with distinct morphological traits were sampled from geographically distant regions in Europe. Plants were cultivated in an oilseed rape field and in insect‐proof cages. Silique and flower morphology, growth, and reproductive traits were measured. The wild radish populations could be discriminated by the morphological traits, but not related to geographic regions. In particular, populations of one region showed wide variability in terms of silique shape and growth behaviour, and small‐sized flowers. Although the origin of morphological diversity in wild radish is unclear, i.e. native or due to gene flow from the cultivated radish or other Brassicaceae, significant morphological divergence was found that could have relevant effects on plant ecology and adaptation. 相似文献
87.
88.
89.
Nie Yuanyuan Xia Hui Ma Xiaosong Lou Qiaojun Liu Yi Zhang Anling Cheng Liang Yan Longan Luo Lijun 《水稻科学》2022,29(3):277-287
Deep rooting is an important trait in rice drought resistance. Genetic resources of deep-rooting varieties are valuable in breeding of water-saving and drought-resistant rice. In the present study, 234 BC2F7 backcross introgression lines were derived from a cross of Dongye 80 (an accession of Dongxiang wild rice as the donor parent) and R974 (an indica restorer line as the recurrent parent). A genetic linkage map containing 1 977 bin markers was constructed by ddRADSeq for QTL analysis. Thirty-one QTLs for four root traits (the number of deep roots, the number of shallow roots, the total number of deep roots and the ratio of deep roots) were assessed on six rice chromosomes in two environments (2020 Shanghai and 2021 Hainan). Two of the QTLs, qDR5.1 and qTR5.2, were located on chromosome 5 in a 70-kb interval. They were detected in both environments. qDR5.1 explained 13.35% of the phenotypic variance in 2020 Shanghai and 12.01% of the phenotypic variance in 2021 Hainan. qTR5.2 accounted for 10.88% and 10.93% of the phenotypic variance, respectively. One QTL (qRDR2.2) for the ratio of deep roots was detected on chromosome 2 in a 210-kb interval and accounted for 6.72% of the phenotypic variance in 2020. The positive effects of these three QTLs were all from Dongxiang wild rice. Furthermore, nine and four putative candidate genes were identified in qRDR2.2 and qDR5.1/qTR5.2, respectively. These findings added to our knowledge of the genetic control of root traits in rice. In addition, this study will facilitate the future isolation of candidate genes of the deep-rooting trait and the utilization of Dongxiang wild rice in the improvement of rice drought resistance. 相似文献
90.