全文获取类型
| 收费全文 | 5424篇 |
| 免费 | 340篇 |
| 国内免费 | 202篇 |
专业分类
| 林业 | 283篇 |
| 农学 | 422篇 |
| 基础科学 | 66篇 |
| 950篇 | |
| 综合类 | 775篇 |
| 农作物 | 356篇 |
| 水产渔业 | 369篇 |
| 畜牧兽医 | 2108篇 |
| 园艺 | 130篇 |
| 植物保护 | 507篇 |
出版年
| 2023年 | 37篇 |
| 2022年 | 39篇 |
| 2021年 | 95篇 |
| 2020年 | 85篇 |
| 2019年 | 101篇 |
| 2018年 | 129篇 |
| 2017年 | 154篇 |
| 2016年 | 156篇 |
| 2015年 | 121篇 |
| 2014年 | 155篇 |
| 2013年 | 237篇 |
| 2012年 | 269篇 |
| 2011年 | 298篇 |
| 2010年 | 244篇 |
| 2009年 | 226篇 |
| 2008年 | 290篇 |
| 2007年 | 282篇 |
| 2006年 | 240篇 |
| 2005年 | 226篇 |
| 2004年 | 203篇 |
| 2003年 | 263篇 |
| 2002年 | 329篇 |
| 2001年 | 322篇 |
| 2000年 | 189篇 |
| 1999年 | 147篇 |
| 1998年 | 40篇 |
| 1997年 | 43篇 |
| 1996年 | 35篇 |
| 1995年 | 46篇 |
| 1994年 | 44篇 |
| 1993年 | 37篇 |
| 1992年 | 47篇 |
| 1991年 | 40篇 |
| 1990年 | 54篇 |
| 1989年 | 51篇 |
| 1988年 | 33篇 |
| 1987年 | 39篇 |
| 1986年 | 30篇 |
| 1985年 | 34篇 |
| 1984年 | 51篇 |
| 1983年 | 27篇 |
| 1982年 | 26篇 |
| 1980年 | 23篇 |
| 1979年 | 28篇 |
| 1978年 | 28篇 |
| 1977年 | 27篇 |
| 1975年 | 25篇 |
| 1974年 | 37篇 |
| 1972年 | 30篇 |
| 1971年 | 37篇 |
排序方式： 共有5966条查询结果，搜索用时 15 毫秒
951.
Gianmarco?Mugnai Federico?RossiEmail authorView author&#;s OrcID profile Vincent?John?Martin?Noah?Linus?Felde Claudia?Colesie Burkhard?Büdel Stephan?Peth Aaron?Kaplan Roberto?De?Philippis 《Biology and Fertility of Soils》2018,54(1):27-40
Soil inoculation with cyanobacteria (cyanobacterization) is a biotechnological method widely studied to improve soil quality and productivity. During their growth on soil, cyanobacteria excrete exopolysaccharides (EPSs) which glue trichomes to soil particles, in a three-dimensional extracellular polymeric matrix. EPS productivity is an important screening parameter to select proficient inoculants and is affected by growth conditions and abiotic stresses. In this study, we evaluated the capability of the cyanobacterium Schizothrix cf. delicatissima AMPL0116 to form biocrusts when inoculated in sand microcosms under stressing conditions, and the characteristics of the synthesized polymeric matrix. In parallel, we evaluated the characteristics of exopolysaccharidic exudates of the strain when grown in liquid culture, under optimal growth setting. Our results pointed out at significant differences of the exopolymers produced in the two conditions in terms of monosaccharidic composition and molecular weight distribution, and proved the capability of S. cf. delicatissima AMPL0116 to form stable bioaggregates on sandy soils. 相似文献
952.
Gerónimo Quiñonez-Barraza Dehai Zhao Héctor M. De Los Santos Posadas José J. Corral-Rivas 《Annals of Forest Science》2018,75(3):78
Key message
More accurate diameter at breast height (dbh)-growth models are needed for developing management tools for mixed-species forests in Mexico. Individual distance-dependent dbh growth models that quantify local neighborhood effects have been developed for four species groups in such forests. The performance of the models is improved by distinguishing between inter- and intraspecific group competitions.Context
The management of mixed-species forests in the northwest of Durango, Mexico, is mainly based on the selection method. Understanding the interspecific and intraspecific competition is critical to developing management tools for such mixed-species forests.Aims
An individual-based distance-dependent modeling approach was used to model the growth of dbh and to evaluate neighborhood effects for four species groups in Mexican mixed-species stands.Methods
Twenty-two species were classified into four groups: Pinus (seven species), other conifers (three species), other broadleaves (four species), and Quercus (eight species). Four methods were used to select neighboring trees and 12 competition indices (CIs) were calculated. Comparisons of the neighboring trees selection methods and CIs and tests of assumptions about neighborhood effects were conducted.Results
Intra-species-group competition significantly reduced diameter growth for all species groups, except for the Quercus group. The Pinus, other conifers, and Quercus groups had significant and negative neighborhood effects on the other broadleaves species group, and not vice versa. The Quercus group also had negative neighborhood effect on the Pinus and other conifers species groups, and not vice versa. The Pinus and other conifers species groups had negative neighborhood effects on each other. All fitted age-independent dbh growth models showed a good of fit to the data (adjusted coefficient of determination larger than 0.977).Conclusion
The growth models can be used to predict dbh growth for species groups and competition in mixed-species stand from Durango, Mexico.953.
954.
为筛选出适宜在干热河谷生态果园种植的豆科牧草。本文设计牧草种类和翻压方式两水平因素,牧草种类是提那罗爪哇大豆(Glycine wightii(Wight and Arn.)Verdcourt‘Tinaroo’)、热研5号柱花草(Stylosanthes giuanensis‘Reyan No.5’)、大翼豆(Macroptilium atropurpureum(DC)Urb)和铺地木蓝(Indigofera endecaphylla Jacq.)4个牧草,翻压方式为翻压与不翻压,观测牧草草产量、地表温湿度、土壤湿度、土壤理化性状变化量;翻压方式观测翻压牧草前后土壤理化性状的变化。结果表明:在芒果园内种植提那罗爪哇大豆在改善果园土壤微环境及作为绿肥翻压提高土壤肥力方面均高于其他3个牧草;大翼豆地上生物量最高,年均干草产量为7 470.463kg·hm-2;热研5号柱花草枯枝落叶量最高,年均3 183.00kg·hm-2。种植牧草小区在调节地表温度及保持土壤水分效果高于未种植区,柱花草在调节地表温度及保持土壤水分的效果高于其他牧草。经济效益与草产量一致。 相似文献
955.
通过重叠PCR扩增得到烟草丛顶病毒(Tobacco bushy top virus,TBTV)中国分离物RdRp的编码序列,构建以pMALC2X为基础载体的原核表达载体pMAL-TB-RdRp。0.5 mM IPTG诱导可特异性表达分子量约为120 kDa的MBP-RdRp融合蛋白。温度梯度实验显示,18℃下诱导表达的MBP-RdRp融合蛋白的可溶性比例较高,约17%;经亲和层析纯化的MBPRdRp可特异性识别TBTV正链和负链的3'末端序列,催化体外复制;对正负链的3'末端的体外复制效率存在差别,识别负链3'末端的体外复制效率明显高于正链3'末端。本研究创建的TBTV RdRp介导的体外复制体系为进一步研究TBTV基因组复制调控奠定了基础。 相似文献
956.
Letícia Aparecida de Moraes Julio Massaharu Marubayashi Valdir Atsushi Yuki Murad Ghanim Vinicius Henrique Bello Bruno Rossitto De Marchi Leonardo da Fonseca Barbosa Laura M. Boykin Renate Krause-Sakate Marcelo Agenor Pavan 《Phytoparasitica》2017,45(4):517-525
In Brazil, the first major invasion event of Bemisia tabaci was that of Middle East–Asia Minor 1 (MEAM1) species, formerly termed as B biotype, which commenced in the 1990s mainly by ornamental plants in São Paulo State. More than two decades after this invasion, the presence of the Mediterranean (MED) species of B. tabaci, formerly Q biotype, was reported in Rio Grande do Sul, the southernmost State of Brazil, and now in São Paulo and Paraná States, in southeastern Brazil. Specimens of whiteflies collected from commercial begonia, hydrangea, petunia and poinsettia greenhouses in São Paulo, and also from begonias and poinsettias collected in flower shops in Paraná, were all identified as belonging to MED species. Furthermore, the secondary endosymbionts Arsenophonus, Hamiltonella and Rickettsia of MED from São Paulo and Paraná were detected by PCR and their presence confirmed by sequencing and FISH analysis, and those results differed from MED detected in Rio Grande do Sul that harbored only Hamiltonella and Cardinium. Our results suggest a new MED invasion into Brazil and is associated with ornamental plants. The two MED populations are genetically different and suggest that they are separate invasions. 相似文献
957.
K. De Jonghe I. De Roo M. Maes 《European journal of plant pathology / European Foundation for Plant Pathology》2017,147(4):749-759
Over the years, real-time PCR outflanked endpoint PCR in phytopathogen diagnostics, mainly because of the increase in sensitivity and timesaving aspects of the technique. However, a time consuming 16S rRNA-based nested PCR method is still the gold standard for phytoplasma diagnosis. This is also the case for phytoplasma detection in Malus, Pyrus and Prunus, the three main host plants of apple proliferation (AP), pear decline (PD) and European stone fruit yellows (ESFY) phytoplasma, respectively. The last decade, loop-mediated isothermal amplification (LAMP) (Notomi et al. 2000) is gaining a lot in significance and is also for phytoplasmas expected to become a widely used reliable diagnostic tool. High specificity and sensitivity which also requires a less stringent need for DNA purification, and the short analysis time and the limited equipment requirements makes the LAMP method a fast and affordable alternative with great point-of-care diagnostic potential. In this paper, we present a LAMP primer set for the ribosomal group 16SrX, containing the important fruit tree phytoplasmas AP, PD and ESFY. The primers were developed and validated for fast and sensitive detection and general use for diagnosis. We foresee that the LAMP technique will also have its application in on-site diagnosis of the fruit tree phytoplasmas during inspections and surveys. 相似文献
958.
Evaluation of a decision support strategy for the control of powdery mildew,Erysiphe necator (Schw.) Burr., in grapevine in the central region of Chile 
下载免费PDF全文
下载免费PDF全文 959.
Moerkens Rob Berckmoes Els Van Damme Veerle Wittemans Lieve Tirry Luc Casteels Hans De Clercq Patrick De Vis Raf 《植物病害和植物保护杂志》2017,124(3):295-303
Journal of Plant Diseases and Protection - Macrolophus pygmaeus Rambur (Hemiptera: Miridae) is a key biological control agent in greenhouse tomato crops. In the present study, we describe the... 相似文献
960.