全文获取类型
| 收费全文 | 804篇 |
| 免费 | 5篇 |
| 国内免费 | 3篇 |
专业分类
| 林业 | 78篇 |
| 农学 | 38篇 |
| 基础科学 | 3篇 |
| 330篇 | |
| 综合类 | 89篇 |
| 农作物 | 15篇 |
| 水产渔业 | 12篇 |
| 畜牧兽医 | 196篇 |
| 园艺 | 13篇 |
| 植物保护 | 38篇 |
出版年
| 2023年 | 5篇 |
| 2022年 | 7篇 |
| 2021年 | 8篇 |
| 2020年 | 8篇 |
| 2019年 | 12篇 |
| 2018年 | 12篇 |
| 2017年 | 9篇 |
| 2016年 | 15篇 |
| 2015年 | 12篇 |
| 2014年 | 12篇 |
| 2013年 | 47篇 |
| 2012年 | 39篇 |
| 2011年 | 51篇 |
| 2010年 | 23篇 |
| 2009年 | 25篇 |
| 2008年 | 41篇 |
| 2007年 | 51篇 |
| 2006年 | 52篇 |
| 2005年 | 55篇 |
| 2004年 | 33篇 |
| 2003年 | 33篇 |
| 2002年 | 40篇 |
| 2001年 | 15篇 |
| 2000年 | 26篇 |
| 1999年 | 18篇 |
| 1998年 | 13篇 |
| 1997年 | 14篇 |
| 1996年 | 14篇 |
| 1995年 | 6篇 |
| 1994年 | 12篇 |
| 1993年 | 8篇 |
| 1992年 | 7篇 |
| 1991年 | 7篇 |
| 1990年 | 8篇 |
| 1989年 | 6篇 |
| 1988年 | 9篇 |
| 1987年 | 8篇 |
| 1986年 | 2篇 |
| 1985年 | 3篇 |
| 1984年 | 3篇 |
| 1978年 | 2篇 |
| 1974年 | 3篇 |
| 1973年 | 6篇 |
| 1970年 | 3篇 |
| 1969年 | 2篇 |
| 1968年 | 3篇 |
| 1966年 | 3篇 |
| 1958年 | 2篇 |
| 1955年 | 2篇 |
| 1863年 | 1篇 |
排序方式： 共有812条查询结果，搜索用时 77 毫秒
21.
Wolfgang Schwenke 《Journal of pest science》1966,39(5):65-67
Summary
Calosoma sycophanta L.(Col., Carabid.) andNabis apterus F.(Hemipt., Nabid.) were observed attacking and feeding onLymantria monacha, Bupalus piniarus andDiprion spec.-larvae and pupae in some pine stands in southern and northern Bavaria 1965. It is intended to investigate the two species in regard to their biology and importance for biological control measures. In the present paper the faunistical and biological data known until now are summarized.
Résumé Pendant l'année de 1965 les insectes prédateursCalosoma sycophanta L.(Col. Carab.) etNabis apterus F.(Hem. Nabid.) furent observés comme ennemies deLymantria monacha, Bupalus pinarius etDiprion frutetorum dans quelques forêts de pins en Bavarie. Les connaissances sur la biologie de ces deux espèces en Europe, quoique incomplètes, sont brièvement résumées pour faciliter des recherches futures.相似文献
22.
23.
With increasing agricultural and industrial use of rare earth elements (REEs), input of REEs into the pedosphere has risen in parallel. Since total REE budgets for soils in Germany are mainly unknown, this pilot study investigates the concentrations of REEs in three loess soil profiles under agricultural land use in the Wetterau region, Germany. There were no significant REE applications in the past, so the presented data can be considered as background concentrations of REEs in soils. In addition to the total REE contents (aqua regia digestion), potentially plant‐available (EDTA) and at actual conditions available, mobile (NH4NO3) REEs have been determined for each horizon. Interactions between REE availability and properties of soils are explained after assessing several chemical and physical properties. The results reveal a wide range of total REE contents, ranging from 222 to 423 mg kg–1. With 10.1% of total REE amounts, the potentially plant‐available proportions of REEs are generally low. In contrast, yttrium, which showed high available proportion of 24.8%, was found to be comparable with Cd. Cerium is the most abundant REE in aqua regia digests, whereas only small amounts in the potentially plant‐available fraction were found. Thus negative cerium anomalies could be concluded concerning its potential availability. Generally, bioavailability of REE had significant correlations between clay contents and Fe and Mn oxides for the majority of REEs. Due to moderately high pH (CaCl2) in soils (average 6.6) the mobile fraction for most of the elements was not detectible. 相似文献
24.
25.
26.
Heinz Benkenstein Michael Baumecker Hans Pagel Wolfgang Krüger 《Archives of Agronomy and Soil Science》2013,59(6):523-538
Langjährig unterlassene Kalkung führte bei mineralisch (NPK) und mit Stallmist gedüngtem Boden in den letzten 20 Versuchsjahren zu pH‐Werten von 4,2 bis 3,6. Die Relativerträge nahmen im Vergleich zur mineralischen Volldüngung (NPKCa) ab. Diese Abnahme war von der Pflanzenart abhängig und bei Sommergerste deutlicher als bei Kartoffeln und Mais. Kalkung des mit NPK gedüngten Bodens erhöhte die Erträge bei Mais bereits im ersten Jahr, bei Gerste und Kartoffeln erst nach mehreren Jahren auf das Niveau der Vergleichsvariante. Bei einer Umstellung von Stallmist auf Stallmist + NPKCa glichen sich die Erträge von Mais und Sommergerste im gleichen Jahr, bei Kartoffeln erst nach mehreren Jahren dem langjährig mit Stallmist + NPKCa gedüngten Prüfglied an. Im langjährig ungedüngten Boden fielen pH‐Wert, KDL und PDL in den letzten 20 Versuchsjahren ebenfalls deutlich ab (pH 3,6 bis 4,1; KDL 2,2 bis 5,0 und PDL 3,5 bis 5,5 mg/100 g Boden). In deren Folge und durch N‐Mangel kam es bei Gerste zum Totalausfall und bei Mais nahezu zum Totalausfall. Bei Kartoffeln lag der Ertrag noch bei 15% der Vergleichsvariante NPKCa. Eine Düngung der Mangelparzellen mit NPKCa ließ den pH‐Wert bereits im ersten Jahr, KDL und PDL erst nach mehrmaliger Düngung in den anzustrebenden Bereich ansteigen. Eine Angleichung der Erträge an die Erträge des durchgehend mit NPKCa gedüngten Prüfgliedes dauerte drei bis vier Jahre. 相似文献
27.
28.
The soil of the long‐term experiment laid out 1949 in Halle has the potential to supply much P. The P taken up by plants where no P (P0) or 15 kg ha−1 yr−1 (P1) was applied was much greater than the P applied as fertilizer (P1). A decrease in yield was measured only after the first 25 years on P0 soils but the P1 treatment has, so far, shown no decrease. Lactate extractions of the soil did not reflect P‐uptake suitably. The release of P from insoluble into water soluble forms was at a minimum after 30 years in P0 soils. P1 soils have now also declined to this minimum value and it remains to be seen whether yields decrease in this treatment in the future. Parallel to this trend, the P sorption increased in P0 soils. The subsoil also seems to be an important source for P supply, possibly influenced by root exudates. Further work is needed to gain a better understanding of soil P dynamics in connection with root exudates and microbes and to identify parameters which will provide more reliable means of calculating fertilizer P requirements. 相似文献
29.
Wolfgang Merbach Joachim Garz Wilfried Schliephake Hermann Stumpe Lothar Schmidt 《植物养料与土壤学杂志》2000,163(6):629-638
Six of originally eight long‐term trials in Halle (Saale), Germany, are still continuing. Five are situated at Julius‐Kühn‐Feld, an experimental station launched by Julius Kühn in Halle in 1866. Apart from the Eternal Rye trial established in 1878, those are phosphorus, potassium, lime, and organic fertilization long‐term trials, all being launched by Karl Schmalfuß in 1949. Other long‐term trials have been terminated, but data are available on the effects of nitrogen fertilization and the physiological reaction of fertilizers. Another long‐term trial in Halle (Adam‐Kuckhoff‐Straße 17b) investigates the influence of fertilization on soil formation from loess. Up to now, the major results are as follows: 1. Changes in soil‐ecological properties due to fertilization and rotation were only evident after 30 years, and new steady states sometimes took 70 years to occur. 2. In the long term, the C‐ and N‐contents of the soil largely depend on the amount of hardly decomposable organic matter applied with organic fertilization. High mineral‐N doses, with consequent high crop and root residues, increased the humus content of the soil. 3. Mineral fertilization can replace organic fertilization in terms of sustainable yield capacity provided equal nutrient amounts were applied. 4. The high P‐supply ability of the soil in Halle could not be explained by traditional soil analysis methods of calculating plant‐available P. With some restrictions, the same is valid for K. 5. At the experimental site, soluble salts (nitrate, sulphate) accumulated in the subsoil. 6. A regular lime demand of central German chernozems could be proved, especially in case of low soil organic matter (SOM) and physiologically acid fertilization. 相似文献
30.
Lothar Schmidt Kristina Warnstorff Hannelore Drfel Peter Leinweber Henning Lange Wolfgang Merbach 《植物养料与土壤学杂志》2000,163(6):639-648
Six forms of fertilizers and three rotations have been examined for 120 years in the ”︁Eternal Rye trial” in Halle (central German arid region, Haplic Phaeozem on sandy loess). Rank analysis, trend analysis and a new component model have been found to be suitable statistical methods to evaluate long‐term results without true replications. In this trial it was shown that mineral fertilization maintains like farmyard manuring the yield potential although at lower content of soil organic matter (SOM). Without fertilization, yield decline was greater with potato and silage maize than winter rye (Secale cereale L.). Deficiencies in N fertilization lead immediately, and in PK supply after more than 20 years, to a significant yield decrease which could be quickly compensated by full fertilization. Rye and maize monocultures also resulted in yield decreases. The establishing of new steady states in the turnover of SOM took about 50 years after changes in fertilization. Contrary to rye monoculture, both silage maize monoculture and potato alternating with winter rye caused considerable decomposition of SOM. According to analytical pyrolysis (Py‐FIMS and Py‐GC/MS), fertilization affects the SOM composition more than rotation. Without fertilization, a higher percentage of thermically stable SOM remained in comparison to the FYM soils. The introduction of potato into the rotation enhanced the content of easily decomposable SOM. 相似文献