全文获取类型
收费全文 | 9434篇 |
免费 | 353篇 |
国内免费 | 786篇 |
专业分类
林业 | 879篇 |
农学 | 690篇 |
基础科学 | 1077篇 |
847篇 | |
综合类 | 3773篇 |
农作物 | 422篇 |
水产渔业 | 275篇 |
畜牧兽医 | 1942篇 |
园艺 | 315篇 |
植物保护 | 353篇 |
出版年
2024年 | 65篇 |
2023年 | 181篇 |
2022年 | 304篇 |
2021年 | 321篇 |
2020年 | 317篇 |
2019年 | 398篇 |
2018年 | 218篇 |
2017年 | 366篇 |
2016年 | 511篇 |
2015年 | 382篇 |
2014年 | 599篇 |
2013年 | 513篇 |
2012年 | 898篇 |
2011年 | 730篇 |
2010年 | 568篇 |
2009年 | 528篇 |
2008年 | 440篇 |
2007年 | 469篇 |
2006年 | 428篇 |
2005年 | 286篇 |
2004年 | 272篇 |
2003年 | 200篇 |
2002年 | 168篇 |
2001年 | 167篇 |
2000年 | 139篇 |
1999年 | 137篇 |
1998年 | 121篇 |
1997年 | 109篇 |
1996年 | 90篇 |
1995年 | 94篇 |
1994年 | 95篇 |
1993年 | 73篇 |
1992年 | 72篇 |
1991年 | 67篇 |
1990年 | 51篇 |
1989年 | 51篇 |
1988年 | 53篇 |
1987年 | 26篇 |
1986年 | 13篇 |
1985年 | 7篇 |
1984年 | 12篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 6篇 |
1973年 | 2篇 |
1956年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
关中地区烤烟良种(系)适应性研究 总被引:2,自引:2,他引:0
以NC89(CK1)、秦烟96(CK2)为对照,对12个烤烟新品种(系)进行了小区比较试验,结果表明:Y8342、中烟202、9407、兴烟1号等4个品种具有较大的发展潜力。 相似文献
102.
菜豆种子普通细菌性疫病菌检测 总被引:2,自引:0,他引:2
由Xanthomonas axonopodis pv. phaseoli和Xanthomonas fuscans subsp. fuscans引起的菜豆普通细菌性疫病是严重影响菜豆生产的限制因子之一,可造成严重的产量和品种损失。染菌种子是病原菌传播的主要途径。本研究对5个菜豆主要产区的60份菜豆种子样品进行普通细菌性疫病菌检测。在MT选择性培养基上有36份种子样品浸提液检测到目标病原菌, 种子样品带菌量为2.49×102~5.20×107 CFU/粒。选择36个分离物接种感病品种“英国红”植株,所有分离物均引起接种植株发病。特异PCR检测结果表明,有20个分离物为X. fuscans subsp. fuscans,16个分离物为X. axonopodis pv. phaseoli。试验结果表明,我国一些菜豆主产区商业种植和研究用种子多数污染普通细菌性疫病菌,建议建立无菌种子生产区和加强种子管理,以有效控制病害发生。 相似文献
103.
In order to improve the properties of rice straw fiber film, one factor contrast test method was employed. Plasticizer type was chosen as input variable, dry tension strength and elongation, wet tension strength and elongation, bursting strength and tearing strength were chosen as indexes. The results showed that there were significant differences among the means of dry tension strength, dry elongation and bursting strength of different plasticizers; there were not significant differences among the means of wet tension strength, wet elongation and tearing strength of different plasticizers; for dry tension strength and elongation, glycerol had a significant difference with sorbitol and PEG, no significant difference was observed between sorbitol and PEG, dry tension strength added glycerol had been reduced 6.8% compared with that added sorbitol, reduced 9.5% compared with that added PEG; elongation had been improved 6.1% and 9.4%, respectively; for bursting strength, sorbitol had a significant difference with glycerol and PEG, no significant difference was observed between glycerol and PEG; bursting strength added glycerol and added PEG had been improved 6.9% and 5.6%, respectively compared with that of the added sorbitol. The results provided a theoretical reference for further improving the straw fiber film manufacturing process. 相似文献
104.
Objective To examine the incidence of positive results in a complement fixation test (CFT) and enzyme-linked immunosorbent assay (ELISA) for Chlamydophila abortus in Australian sheep and how this incidence differs with state of origin, age, sex, breed and property. To examine the consequences in relation to rejection of breeder sheep for export.
Design Collection of blood samples from 891 sheep on 109 properties in southern Australia. All samples had a unique, coded property identification.
Procedure The samples were tested using the Institut Pourquier Chlamydophila abortus antibody ELISA (rELISA) and a CFT. Residual maximum likelihood analyses of the sample to positive ratio of the corrected optical density for the rELISA and generalised linear mixed model analyses of the CFT outcomes were carried out.
Results The sample to positive ratio of the corrected optical density values of the rELISA did not differ between sex, age, breed or state of origin, but differed greatly between properties. The CFT outcome did not differ between age, breed or state of origin, but differed greatly between properties and was more often positive with rams than with ewes.
Conclusion Positive outcomes to C. abortus antibody tests are very common in Australia. Rams have a particularly high incidence of positive results with the CFT. Rejection of sheep and property consignments is likely to be very common with all tests and situations examined except for the CFT (at 1:32 dilution) in ewes. 相似文献
Design Collection of blood samples from 891 sheep on 109 properties in southern Australia. All samples had a unique, coded property identification.
Procedure The samples were tested using the Institut Pourquier Chlamydophila abortus antibody ELISA (rELISA) and a CFT. Residual maximum likelihood analyses of the sample to positive ratio of the corrected optical density for the rELISA and generalised linear mixed model analyses of the CFT outcomes were carried out.
Results The sample to positive ratio of the corrected optical density values of the rELISA did not differ between sex, age, breed or state of origin, but differed greatly between properties. The CFT outcome did not differ between age, breed or state of origin, but differed greatly between properties and was more often positive with rams than with ewes.
Conclusion Positive outcomes to C. abortus antibody tests are very common in Australia. Rams have a particularly high incidence of positive results with the CFT. Rejection of sheep and property consignments is likely to be very common with all tests and situations examined except for the CFT (at 1:32 dilution) in ewes. 相似文献
105.
山毛豆对小白鼠的亚慢性毒性试验研究 总被引:1,自引:0,他引:1
为开发山毛豆(Tephrosia canadida DC.)作为蛋白质饲料资源,进行了山毛豆亚慢性毒性试验,即在饲粮中用山毛豆叶粉替代20%、40%和60%的基础日粮饲喂小白鼠,对各组小白鼠的采食、生长、脏器系数及组织切片等指标进行了测定和分析。结果表明:①试验期间,小白鼠活动正常,对照组和试验组小白鼠都没有死亡;②试验组小白鼠的各脏器无明显肉眼可见剖检病变;③试验组小白鼠的各脏器系数与对照组差异不显著(P0.05);④40%和60%试验组小白鼠肝脏、肾脏的组织形态发生轻微变化,其他脏器均正常。研究结果表明,山毛豆草粉可安全用于动物饲料中。 相似文献
106.
Bayesian inference towards the resolution of molecular evolution:application to the "Trichoderma harzianum sensu lato" clade 下载免费PDF全文
Druzhinina I S Kubicek C P 《浙江大学学报(农业与生命科学版)》2004,30(4):458-458
The Hypocrea lixii/Trichoderma harzianum species aggregate contains a group of taxa (H. lixii /T. harzianum, T. aggressivum, T. tomentosum, T. cerinum, T. velutinum, H. tawa) of which some (e.g. T. harzianum) are important for biocontrol of plant pathogenic fungi in agriculture, whereas others are aggressive pathogens of Agaricus spp. and Pleurotus spp. in mushroom farms (T. aggressivum), or opportunistic pathogens of immunocompromised mammals including humans (T. harzianum). We ch… 相似文献
107.
108.
109.
中华鳖致病性嗜水气单胞菌的分离鉴定及药敏试验 总被引:3,自引:0,他引:3
对江西省进贤县某中华鳖养殖场送检的2只患病中华鳖进行细菌分离,且对分离的细菌进行培养特性观察、生化特性鉴定、毒力因子检测、毒力基因PCR检测、实验动物攻毒及体外药敏试验。结果表明,从2只中华鳖肝脏分离到3株菌,均为革兰阴性短杆菌,其中体型稍大中华鳖2株,体型稍小中华鳖1株;经过实验动物感染试验得出3株菌都为强毒力致病菌;通过生化鉴定、毒力因子及PCR检测确定为嗜水气单胞菌;体外药敏试验结果显示,3株菌对头孢曲松都高度敏感,对利福平、甲氧苄啶、氨苄青霉素都不敏感。 相似文献
110.