全文获取类型
收费全文 | 286篇 |
免费 | 11篇 |
专业分类
林业 | 49篇 |
农学 | 26篇 |
基础科学 | 1篇 |
78篇 | |
综合类 | 33篇 |
农作物 | 6篇 |
水产渔业 | 9篇 |
畜牧兽医 | 72篇 |
园艺 | 3篇 |
植物保护 | 20篇 |
出版年
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 6篇 |
2014年 | 10篇 |
2013年 | 17篇 |
2012年 | 6篇 |
2011年 | 9篇 |
2010年 | 3篇 |
2009年 | 7篇 |
2008年 | 20篇 |
2007年 | 7篇 |
2006年 | 10篇 |
2005年 | 10篇 |
2004年 | 9篇 |
2003年 | 13篇 |
2002年 | 9篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 7篇 |
1998年 | 3篇 |
1997年 | 6篇 |
1996年 | 7篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 8篇 |
1992年 | 3篇 |
1991年 | 13篇 |
1990年 | 5篇 |
1987年 | 4篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1974年 | 2篇 |
1973年 | 6篇 |
1972年 | 3篇 |
1969年 | 2篇 |
1956年 | 2篇 |
1955年 | 3篇 |
1948年 | 2篇 |
1939年 | 2篇 |
1935年 | 2篇 |
1931年 | 3篇 |
1930年 | 3篇 |
1926年 | 2篇 |
1925年 | 2篇 |
1915年 | 2篇 |
1899年 | 2篇 |
排序方式: 共有297条查询结果,搜索用时 15 毫秒
1.
2.
Gartenbaurat Friedrich Wenck 《Journal of pest science》1948,21(2):21-22
Ohne Zusammenfassung 相似文献
3.
Joo Carlos de Moraes S Lucien Sguy Florent Tivet Rattan Lal Serge Bouzinac Paulo Rogrio Borszowskei Clever Briedis Josiane Burkner dos Santos Daiani da Cruz Hartman Clayton Giani Bertoloni Jadir Rosa Theodor Friedrich 《Land Degradation \u0026amp; Development》2015,26(6):531-543
The continuous use of plowing for grain production has been the principal cause of soil degradation. This project was formulated on the hypothesis that the intensification of cropping systems by increasing biomass‐C input and its biodiversity under no‐till (NT) drives soil restoration of degraded agro‐ecosystem. The present study conducted at subtropical [Ponta Grossa (PG) site] and tropical regions [Lucas do Rio Verde, MT (LRV) site] in Brazil aimed to (i) assess the impact of the continuous plow‐based conventional tillage (CT) on soil organic carbon (SOC) stock vis‐à‐vis native vegetation (NV) as baseline; (ii) compare SOC balance among CT, NT cropping systems, and NV; and (iii) evaluate the redistribution of SOC stock in soil profile in relation to soil resilience. The continuous CT decreased the SOC stock by 0·58 and 0·67 Mg C ha−1 y−1 in the 0‐ to 20‐cm depth at the PG and LRV sites, respectively, and the rate of SOC sequestration was 0·59 for the PG site and ranged from 0·48 to 1·30 Mg C ha−1 y−1 for the LRV site. The fraction of C input by crop residues converted into SOC stock was ~14·2% at the PG site and ~20·5% at the LRV site. The SOC resilience index ranged from 0·29 to 0·79, and it increased with the increase in the C input among the NT systems and the SOC sequestration rates at the LRV site. These data support the hypothesis that NT cropping systems with high C input have a large potential to reverse the process of soil degradation and SOC decline. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
4.
Friedrich Mechelke 《Genetic Resources and Crop Evolution》1955,3(1):127-135
Zusammenfassung Die Gerstensorte Heines Haisa und die PrimitivformHordeum agriocrithon sind sommerannuell. Beide reagieren auf den Einfluß niedriger Temperaturen während der Keimung mit der Ausbildung einer spezialsegmentartigen Einschnürung im kurzen Arm des VII. Chromosoms in Wurzelspitzen-Metaphasen. Im Gegensatz dazu ist bei der winterannuellen Form Friedrichswerther Berg und dem annähernd winterannuellenHordeum spontaneum die Tendenz zu der gleichen Reaktion bedeutend geringer oder überhaupt nicht vorhanden. Die Möglichkeit, daß die Eigenschaft sommer- bzw. winterannuell in Beziehung zur Funktion heterochromatischer Segmente steht, wird kurz diskutiert. 相似文献
5.
Top 20 environmental weeds for classical biological control in Europe: a review of opportunities, regulations and other barriers to adoption 总被引:4,自引:3,他引:4
Classical biological control remains the only tool available for permanent ecological and economic management of invasive alien species that flourish through absence of their co‐evolved natural enemies. As such, this approach is recognized as a key tool for alien species management by the Convention on Biological Diversity (CBD), the European and Mediterranean Plant Protection Organization (EPPO) and the European Strategy on Invasive Alien Species (ESIAS). Successful classical biological control programmes abound around the world, despite disproportionate attention being given to occasional and predictable non‐target impacts. Despite more than 130 case histories in Europe against insect pests, no exotic classical biological control agent has been released in the EU against an alien invasive weed. This dearth has occurred in the face of increasing numbers of exotic invasive plants being imported and taking over National Parks, forests and amenity areas in this region, as well as a global increase in the use of classical biological control around the world. This paper reviews potential European weed targets for classical biological control from ecological and socioeconomic perspectives using the criteria of historical biological control success, taxonomic isolation from European native flora, likely availability of biological control agents, invasiveness outside Europe and value to primary industry and horticulture (potential for conflicts of interest). We also review why classical biological control of European exotic plants remains untested, considering problems of funding and public perception. Finally, we consider the regulatory framework that surrounds such biological control activities within constituent countries of the EU to suggest how this approach may be adopted in the future for managing invasive exotic weeds in Europe. 相似文献
6.
7.
8.
Friedrich Moll 《Forstwissenschaftliches Centralblatt》1925,47(3):225-230
Ohne Zusammenfassung 相似文献
9.
Dr. Friedrich Zacher 《Journal of pest science》1935,11(6):63-66
Ohne Zusammenfassung
Mit 1 Abbildung. 相似文献
10.
Friedrich Moll 《Forstwissenschaftliches Centralblatt》1926,48(8):541-544
Ohne Zusammenfassung 相似文献