全文获取类型
收费全文 | 10646篇 |
免费 | 815篇 |
国内免费 | 676篇 |
专业分类
林业 | 1175篇 |
农学 | 1646篇 |
基础科学 | 622篇 |
1852篇 | |
综合类 | 2420篇 |
农作物 | 556篇 |
水产渔业 | 643篇 |
畜牧兽医 | 2217篇 |
园艺 | 244篇 |
植物保护 | 762篇 |
出版年
2024年 | 18篇 |
2023年 | 110篇 |
2022年 | 179篇 |
2021年 | 272篇 |
2020年 | 297篇 |
2019年 | 343篇 |
2018年 | 348篇 |
2017年 | 396篇 |
2016年 | 361篇 |
2015年 | 456篇 |
2014年 | 409篇 |
2013年 | 531篇 |
2012年 | 594篇 |
2011年 | 707篇 |
2010年 | 621篇 |
2009年 | 591篇 |
2008年 | 631篇 |
2007年 | 597篇 |
2006年 | 561篇 |
2005年 | 544篇 |
2004年 | 266篇 |
2003年 | 248篇 |
2002年 | 192篇 |
2001年 | 271篇 |
2000年 | 288篇 |
1999年 | 335篇 |
1998年 | 244篇 |
1997年 | 204篇 |
1996年 | 231篇 |
1995年 | 189篇 |
1994年 | 149篇 |
1993年 | 144篇 |
1992年 | 118篇 |
1991年 | 121篇 |
1990年 | 95篇 |
1989年 | 82篇 |
1988年 | 75篇 |
1987年 | 61篇 |
1986年 | 45篇 |
1985年 | 26篇 |
1984年 | 20篇 |
1983年 | 15篇 |
1982年 | 11篇 |
1980年 | 6篇 |
1979年 | 12篇 |
1978年 | 8篇 |
1971年 | 6篇 |
1966年 | 6篇 |
1965年 | 5篇 |
1892年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
41.
42.
43.
Y. J. Huang C. Toscano-Underwood B. D. L. Fitt † X. J. Hu A. M. Hall 《Plant pathology》2003,52(2):245-255
Ascospores of both A-group and B-group Leptosphaeria maculans germinated at temperatures from 5 to 20°C on leaves of oilseed rape. Germination of ascospores of both groups started 2 h after inoculation and percentage germination reached its maximum about 14 h after inoculation at all temperatures. Both the percentage of A-/B-group ascospores that had germinated after 24 h incubation and germ tube length increased with increasing temperature from 5 to 20°C. Germ tubes from B-group ascospores were longer than those from A-group ascospores at all temperatures, with the greatest difference at 20°C. Hyphae from ascospores of both groups penetrated the leaves predominantly through stomata, at temperatures from 5 to 20°C. A-group ascospores produced highly branched hyphae that grew tortuously, whereas B-group ascospores produced long, straight hyphae. The percentage of germinated ascospores that penetrated stomata increased with increasing temperature from 5 to 20°C and was greater for A-group than for B-group L. maculans after 40 h incubation. 相似文献
44.
A. van Maanen X.-M. Xu 《European journal of plant pathology / European Foundation for Plant Pathology》2003,109(7):669-682
An epidemic is the progress of disease in time and space. Each epidemic has a structure whose temporal dynamics and spatial patterns are jointly determined by the pathosystem characteristics and environmental conditions. One of the important objectives in epidemiology is to understand such spatio-temporal dynamics via mathematical and statistical modelling. In this paper, we outline common methodologies that are used to quantify and model spatio-temporal dynamics of plant diseases, with emphasis on developing temporal forecast models and on quantifying spatial patterns. Several examples of epidemiological models in cereal crops are described, including one for Fusarium head blight. 相似文献
45.
Rapid detection of Phytophthora cinnamomi using PCR with primers derived from the Lpv putative storage protein genes 总被引:1,自引:1,他引:1
Phytophthora cinnamomi is an ecologically and economically important pathogen. In this study, PCR assays were developed with primer pair LPV2 or LPV3 for rapid detection and identification of this organism. Both primer pairs were selected from putative storage protein genes. The specificity of these primer pairs was evaluated against 49 isolates of P. cinnamomi , 102 isolates from 30 other Phytophthora spp., 17 isolates from nine Pythium spp. and 43 isolates of other water moulds, bacteria and true fungi. PCR with both primer pairs amplified the DNA from all isolates of P. cinnamomi regardless of origin. The LPV3 primers showed adequate specificity among all other species tested. The LPV2 primers cross-reacted with some species of Pythium and true fungi, but not with any other Phytophthora species. PCR with the LPV3 primers detected the pathogen at levels of a single chlamydospore or 10 zoospores in repeated tests. The PCR assay was at least 10 times more sensitive than the plating method for detection of the pathogen from artificially infested soilless medium, and, to a lesser extent, from naturally infected plants. PCR with LPV3 primers can be a useful tool for detecting P. cinnamomi from soilless media and plant tissues at ornamental nurseries, whereas the LPV2 primers can be an effective alternative for identification of this species from pure culture. Applications of these assays for detection of P. cinnamomi in other environments were also discussed. 相似文献
46.
47.
48.
利用微卫星标记分析贵州5个地方鸡品种遗传多样性 总被引:2,自引:0,他引:2
通过选用30个多态性较好的微卫星标记,检测了贵州省5个地方鸡品种:竹乡鸡、威宁鸡、黔东南小香鸡、高脚鸡、乌蒙乌骨鸡的遗传多样性。计算了各群体的平均遗传杂合度(H)、多态信息含量(PIC)和群体间的DA遗传距离。结果表明:在5个品种中,杂合度最低的是高脚鸡,为0.501,杂合度最高的是竹乡鸡,为0.673,因此贵州各地方鸡品种的杂合度相差较大,据分析可能是由于交通闭塞,形成了家禽品种的多种多型,而且杂合度的高低与PIC值的大小体现了较高的一致性;用UPGMA法进行聚类分析,结果6个鸡品种被聚为3类:竹乡鸡、黔东南小香鸡和威宁鸡聚为一类,乌蒙乌骨鸡自聚为一类;高脚鸡独自聚为一类。这与几个鸡品种的来源、分化、选育历史及地理分布是一致的。 相似文献
49.
James F X Wellehan Maud Lafortune Darryl J Heard 《Journal of zoo and wildlife medicine》2004,35(2):197-202
Traumatic elbow luxation was diagnosed in a common squirrel monkey (Saimiri sciureus) and a bonnet macaque (Macaca radiata). In the common squirrel monkey, the luxation was complicated by an ulnar fracture and would not stay reduced when attempts at closed reduction were made. The luxation was surgically reduced and a transarticular type I external skeletal fixator was placed. In the bonnet macaque, closed reduction was performed and the elbow was stabilized using a cast. Both monkeys regained good function of the injured elbows. 相似文献