全文获取类型
收费全文 | 1724篇 |
免费 | 88篇 |
国内免费 | 108篇 |
专业分类
林业 | 100篇 |
农学 | 148篇 |
基础科学 | 6篇 |
98篇 | |
综合类 | 662篇 |
农作物 | 229篇 |
水产渔业 | 51篇 |
畜牧兽医 | 354篇 |
园艺 | 180篇 |
植物保护 | 92篇 |
出版年
2024年 | 3篇 |
2023年 | 20篇 |
2022年 | 24篇 |
2021年 | 37篇 |
2020年 | 44篇 |
2019年 | 33篇 |
2018年 | 20篇 |
2017年 | 29篇 |
2016年 | 71篇 |
2015年 | 58篇 |
2014年 | 126篇 |
2013年 | 102篇 |
2012年 | 81篇 |
2011年 | 124篇 |
2010年 | 113篇 |
2009年 | 145篇 |
2008年 | 113篇 |
2007年 | 130篇 |
2006年 | 118篇 |
2005年 | 74篇 |
2004年 | 59篇 |
2003年 | 39篇 |
2002年 | 35篇 |
2001年 | 30篇 |
2000年 | 40篇 |
1999年 | 36篇 |
1998年 | 30篇 |
1997年 | 27篇 |
1996年 | 18篇 |
1995年 | 34篇 |
1994年 | 23篇 |
1993年 | 22篇 |
1992年 | 14篇 |
1991年 | 15篇 |
1990年 | 8篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有1920条查询结果,搜索用时 15 毫秒
71.
Downy mildew (DM) caused by Peronospora arborescens is the most destructive disease of opium poppy which assumes considerable importance in India and other poppy growing countries.
The present study was aimed at identification and evaluation of stable resistance sources of DM in opium poppy. Furthermore,
genetic variability and inheritance pattern of DM resistance has also been studied which can help in making strategy for crop
improvement. Evaluation of 35 selected germplasm accessions of opium poppy under glasshouse and field conditions during the
three consecutive years (2004–2005 to 2006–2007) resulted in identification of two genotypes (I-14 and Pps-1) as highly resistant
and stable sources for DM resistance. Genetic studies of DM resistance revealed polygenic control with the dominance of susceptibility
over resistance. Significant reciprocal differences were found largely due to maternal transmission of DM resistance indicating
the involvement of cytoplasmic genes in addition to nuclear control. Analysis of genetic variability and selection parameters
indicated predominance of additive effects for DM resistance and other yield contributing traits. Multivariate analysis resulted
in classification of 35 selected accessions into 11 different clusters revealing very high level of diversity among the genotypes.
Cluster analysis suggested that hybridization program involving genotypes from cluster V (which included highly resistant
genotypes Pps-1 and I-14) and cluster IX (which included highly susceptible Jawahar-16 having good economically important
traits like seed yield) could be expected to give best recombinants for improvement in terms of DM resistance and high seed
and straw yield in opium poppy. Analysis of selection parameters like heritability and genetic advance also suggested that
simple selection methods will be effective in stabilizing resistance traits following hybridization with high yielding genotypes. 相似文献
72.
73.
Eleonora Barilli Josefina C. Sillero Mnica Fernndez-Aparicio Diego Rubiales 《Field Crops Research》2009,114(2):198-203
A germplasm collection of 2759 pea accessions was screened for resistance against Uromyces pisi (Pers.) Wint. All accessions displayed a compatible interaction (high infection type) both in adult plants under field conditions and in seedlings under growth chamber conditions, but with varying levels of disease reduction. The identified resistance was based on reduction of disease severity with no associated host cell necrosis, which fits the definition of Partial Resistance. No complete resistance or incomplete resistance based on hypersensitivity was observed. 相似文献
74.
75.
几种药剂对小麦黄矮病的防治效果 总被引:5,自引:0,他引:5
为明确病毒抑制剂对小麦黄矮病的预防和防治效果,在小麦起身期将大麦黄矮病毒GAV株系接种于小麦陕恳9740上,喷施杀虫剂(2.5%吡虫啉可湿性粉剂2000倍液)与病毒抑制剂(20%病毒A可湿性粉剂500倍液、3.95%病毒必克可湿性粉剂500倍液、5%菌毒清水剂500倍液和2%菌克毒克水剂300倍液)的不同组合,于小麦开花期统计发病率、病情指数和小麦叶片黄化率,结果表明,各组合均能早期预防和防治小麦黄矮病发生和发展,且预防效果优于防治效果,其中病毒必克与吡虫啉组合的平均预防和防治效果最显著,分别为58.08%和53.03%.进一步利用病毒必克在室内进行防治性试验,发现病毒必克能够抑制GAV对叶绿素的破坏,可减轻大麦黄矮病毒对小麦的危害. 相似文献
76.
D. E. te Beest M. W. Shaw S. Pietravalle F. van den Bosch 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(3):413-425
Disease–weather relationships influencing Septoria leaf blotch (SLB) preceding growth stage (GS) 31 were identified using
data from 12 sites in the UK covering 8 years. Based on these relationships, an early-warning predictive model for SLB on
winter wheat was formulated to predict the occurrence of a damaging epidemic (defined as disease severity of 5% or > 5% on
the top three leaf layers). The final model was based on accumulated rain > 3 mm in the 80-day period preceding GS 31 (roughly
from early-February to the end of April) and accumulated minimum temperature with a 0°C base in the 50-day period starting
from 120 days preceding GS 31 (approximately January and February). The model was validated on an independent data set on
which the prediction accuracy was influenced by cultivar resistance. Over all observations, the model had a true positive
proportion of 0.61, a true negative proportion of 0.73, a sensitivity of 0.83, and a specificity of 0.18. True negative proportion
increased to 0.85 for resistant cultivars and decreased to 0.50 for susceptible cultivars. Potential fungicide savings are
most likely to be made with resistant cultivars, but such benefits would need to be identified with an in-depth evaluation. 相似文献
77.
Yosuke Matsushita Tomio Usugi Shinya Tsuda 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(2):349-352
We characterised the host range and physical properties of Tomato chlorotic dwarf viroid. Among the 46 plant species inoculated with the viroid, two in the family Compositae and 23 in the family Solanaceae were
found to be systemic hosts. The viroids in the crude sap from diseased tomato plants were thermally inactivated by heating
to 100°C for at least 40 min. These viroids also lost their infectivity when diluted in phosphate buffer to at least 10−6, or after 3 days of incubation at room temperature. However, the infectivity of the viroids in dried crude sap from the plants
persisted throughout the 50-day test period. 相似文献
78.
小波特征与传统光谱特征估测冬小麦条锈病病情严重度的对比研究 总被引:2,自引:0,他引:2
为探讨通过小波特征监测小麦条锈病发病程度的可行性,利用连续小波变换提取的小麦冠层光谱350~1 300 nm范围内的9个小波特征和传统光谱特征(植被指数、一阶微分变换特征和连续统特征),借助偏最小二乘回归(PLSR)建立反演模型,分别将传统光谱特征(SFs)、小波特征(WFs)及传统光谱特征与小波特征结合(SFs & WFs)作为模型的输入,对小麦条锈病病情进行反演。结果表明:(1)小波特征与条锈病严重度的相关性比传统光谱特征强;(2)基于小波特征的模型估测精度(R为0.837)优于基于传统光谱特征的模型估测精度(R为0.824);(3)传统光谱特征与小波特征结合的模型精度最高,R为0.876,RMSE仅为0.096,因而传统光谱特征与小波特征相结合能够更好地对小麦条锈病病情严重度进行估测。 相似文献
79.
小麦不同抗白粉病基因及品种在成都平原抗病的有效性 总被引:1,自引:0,他引:1
为了解小麦含已知抗白粉病基因材料及审定品种在成都平原对白粉病的抗性表现,2015-2017年在四川省江油市武都镇(104.47°E,31.52°N)和广汉市连山镇(104.18°E,30.59°N)设置病圃,种植42份含已知抗白粉病基因的材料以及85份小麦审定品种,于2016-2018年乳熟后期调查病害级别、普遍率和严重度。结果表明,已知抗白粉病基因材料中,Coker983(Pm5+6)、Wembley(Pm12)、Brigand(Pm16)、南农9918(Pm21)、赤牙糙(Pm24)、NCD7(Pm34)、NCD3(Pm35)、NCD4(Non-Pm1)、复壮30(Pm5e)和Tabasco(Pm46)在两个病圃(2016和2018年)均表现抗白粉病,而Kavkaz(Pm8)、W150(Pm3e)、Hope/8cc(Pm5a)、Timgalen(Pm6)和5P27(Pm30)在两个病圃内均表现感病。85份小麦审定品种中,国豪麦3号、蜀麦375、蜀麦482、杏麦2号、绵阳29号、绵阳33、绵麦228、西科麦5号和良麦4号9个品种连续三年(2016-2018年)在两地均表现抗病,有37个品种三年在两地均表现感病。其余27个含已知抗性基因材料和39个小麦审定品种的抗病性表现则在不同地点和年份并不稳定。 相似文献
80.
CHEN Ting CHEN Zheng Atul Prakash SATHE ZHANG Zhihong LI Liangjian SHANG Huihui TANG Shaoqing ZHANG Xiaobo WU Jianli 《水稻科学》2019,26(6):372-383
We here reported the identification and characterization of a novel gain-of-function spotted-leaf 26(Spl26) mutant from an ethylmethylsulfone(EMS)-induced rice cultivar IR64. Spl26 displayed reddishbrown lesions that firstly appeared on the leaf tips at the early tillering stage and spread gradually downward to cover the whole leaf blades that wilted subsequently. The lesion development was lightdependent under natural conditions. Spl26 exhibited impaired photosynthetic capacity with decreased chlorophyll content and lowered photosynthetic parameters which ultimately led to the poor performance of agronomic traits. Severe cell death occurred in Spl26 in accompany with increased malonaldehyde level and membrane ion leakage rate, elevated reactive oxygen species(ROS) accumulation, altered ROS scavenging activities, increased DNA fragmentation and decreased soluble protein levels. Defense responses were activated in Spl26 with enhanced resistance to rice bacterial blight, up-regulation of defense response genes and altered endogenous hormone levels. The spotted-leaf phenotype is controlled by a single dominant nuclear gene localized to a 305 kb region between RM5490 and In Del42 on the short arm of chromosome 7. The data suggested that Spl26 is a novel gain-of-function spotted-leaf mutant with enhanced bacterial disease resistance and immunity-associated premature leaf senescence and would provide the basis for cloning of the target gene. 相似文献