全文获取类型
收费全文 | 271篇 |
免费 | 6篇 |
国内免费 | 3篇 |
专业分类
林业 | 78篇 |
农学 | 7篇 |
基础科学 | 1篇 |
56篇 | |
综合类 | 23篇 |
农作物 | 6篇 |
水产渔业 | 6篇 |
畜牧兽医 | 66篇 |
园艺 | 7篇 |
植物保护 | 30篇 |
出版年
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 7篇 |
2013年 | 16篇 |
2012年 | 22篇 |
2011年 | 10篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 18篇 |
2007年 | 8篇 |
2006年 | 13篇 |
2005年 | 14篇 |
2004年 | 10篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1987年 | 2篇 |
1976年 | 2篇 |
1973年 | 2篇 |
1968年 | 2篇 |
1950年 | 2篇 |
1938年 | 5篇 |
1936年 | 4篇 |
1933年 | 3篇 |
1932年 | 1篇 |
1931年 | 2篇 |
1930年 | 4篇 |
1928年 | 4篇 |
1926年 | 4篇 |
1925年 | 8篇 |
1924年 | 4篇 |
1923年 | 2篇 |
1922年 | 3篇 |
1921年 | 9篇 |
1920年 | 2篇 |
1918年 | 8篇 |
1909年 | 3篇 |
1906年 | 1篇 |
1857年 | 1篇 |
排序方式: 共有280条查询结果,搜索用时 31 毫秒
11.
12.
Ajwa HA Trout T Mueller J Wilhelm S Nelson SD Soppe R Shatley D 《Phytopathology》2002,92(12):1349-1355
ABSTRACT Strawberry fields in California (9,500 ha annually) are pre-plant fumigated with methyl bromide and chloropicrin to prevent serious soil pest and disease problems. Although soil fumigation with methyl bromide has ensured stability of strawberry production, its use is being discontinued because of its effect on stratospheric ozone. The likely short-term alternatives such as 1,3-dichloropropene, chloropicrin, and metham sodium, although not ozone depleters, are potentially hazardous to the environment and humans if applied improperly. Water-soluble formulations of alternative fumigants can be applied through drip irrigation systems established to irrigate crops. In comparison to conventional shank methods of injection, application of soluble formulations through drip irrigation systems would be economical and environmentally friendly, reduce worker exposure, and allow for simultaneous or sequential application of a combination of fumigants. This paper discusses techniques developed to apply alternative fumigants through drip irrigation systems, and reviews ongoing studies to determine optimum application rates, soil conditions, plastic mulches, and amount of irrigation water used to apply these alternative fumigants. 相似文献
13.
Heinrich Wilhelm Weber 《Forstwissenschaftliches Centralblatt》1922,44(6):214-224
Ohne Zusammenfassung 相似文献
14.
15.
Wilhelm Kuhn 《Forstwissenschaftliches Centralblatt》1918,40(8-9):307-321
Ohne Zusammenfassung 相似文献
16.
Dr. Wilhelm Berwig 《Journal of pest science》1964,37(2):25-26
Ohne Zusammenfassung 相似文献
17.
Somatic embryos of oak (Quercus robur L.) were matured on P24 media differing in gel strength (0.8, 0.9 and 1.0% (w/v) agar). Viscosity and osmotic potential (Psipi,medium) of the media were determined. Developing cotyledonary embryos were analyzed at maturity Stages I-III for water content, osmotic potential (Psipi,embryo) and concentrations of abscisic acid (ABA) and proline. Proliferation of embryogenic tissue, germination rates and the number of embryos formed were also determined in order to relate embryo quality to physiological parameters. Viscosity increased with agar concentration, a phenomenon apparently related to water availability. Many Stage III embryos with high germination potentials were obtained on P24 medium containing 1.0% agar. Embryo water content decreased progressively from 94 to 80% during embryo maturation. Stage I and II embryos that matured on media containing 0.8 or 0.9% agar had similar values of Psipi,embryo, whereas Psipi,embryo of Stage III embryos that matured on medium containing 1.0% agar was significantly lower, although Psipi,medium was unaffected by gel strength. Stage III embryos showed a nearly 16-fold increase in proline concentration and a 50% decrease in ABA concentration compared with Stage I embryos. We conclude that tissue water status and a complex relationship between ABA and proline concentrations, modulated by medium gel strength, are important factors in the maturation process and the quality of oak somatic embryos. 相似文献
18.
The degradation of beech bark by three wood-decaying fungi has been analyzed at the ultra-structural level and the micromorphological changes occurring in the walls of the diverse cell types compared with the decay pattern in wood cells. 相似文献
19.
20.
Shantharaj Deepak Sathyanarayana Niranjan-Raj Shekar Shailasree Ramachandra K. Kini Wilhelm Boland Hunthrike S. Shetty Axel Mithfer 《Physiological and Molecular Plant Pathology》2007,71(1-3):96-105
The synthetic 1-oxo-indanoyl-l-isoleucine methyl ester (Ind-Ile-Me) represents a highly active mimic of octadecanoic phytohormones, which are involved in plant defenses against pathogens and pests. Seed treatments and foliar spray with Ind-Ile-Me were tested for induced resistance against downy mildew disease caused by the phytopathogenic oomycete Sclerospora graminicola in pearl millet (Pennisetum glaucum) under greenhouse and field conditions. Under greenhouse conditions, a 50% protection level was achieved after seed treatment. Seed treatment in combination with foliar spray resulted in 60% protection. The induction of resistance was correlated with the enhanced activities of defense-related proteins such as phenylalanine-ammonia-lyase, peroxidase, and enhanced level of hydroxyproline-rich glycoproteins. Under field conditions, a maximum protection of 62% was recorded upon seed treatment along with foliar spray. Hence, it infers that Ind-Ile-Me can be used as a valuable protection compound at least in downy mildew disease management. 相似文献