全文获取类型
收费全文 | 283篇 |
免费 | 4篇 |
专业分类
林业 | 96篇 |
农学 | 4篇 |
91篇 | |
综合类 | 22篇 |
农作物 | 8篇 |
水产渔业 | 2篇 |
畜牧兽医 | 36篇 |
园艺 | 5篇 |
植物保护 | 23篇 |
出版年
2020年 | 3篇 |
2014年 | 3篇 |
2013年 | 15篇 |
2012年 | 11篇 |
2011年 | 14篇 |
2010年 | 4篇 |
2009年 | 10篇 |
2008年 | 15篇 |
2007年 | 13篇 |
2006年 | 8篇 |
2005年 | 8篇 |
2004年 | 10篇 |
2003年 | 13篇 |
2002年 | 8篇 |
2001年 | 3篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1981年 | 3篇 |
1976年 | 2篇 |
1973年 | 2篇 |
1968年 | 2篇 |
1967年 | 2篇 |
1965年 | 2篇 |
1959年 | 3篇 |
1958年 | 2篇 |
1957年 | 2篇 |
1956年 | 2篇 |
1955年 | 2篇 |
1954年 | 2篇 |
1950年 | 2篇 |
1942年 | 2篇 |
1938年 | 8篇 |
1936年 | 6篇 |
1935年 | 4篇 |
1931年 | 5篇 |
1930年 | 6篇 |
1929年 | 5篇 |
1928年 | 5篇 |
1927年 | 5篇 |
1926年 | 10篇 |
1925年 | 4篇 |
1907年 | 2篇 |
1895年 | 4篇 |
排序方式: 共有287条查询结果,搜索用时 703 毫秒
251.
Marian Wiwart Elżbieta Suchowilska Wolfgang Kandler Michael Sulyok Paweł Groenwald Rudolf Krska 《Genetic Resources and Crop Evolution》2013,60(8):2359-2373
Nine spring lines of Polish wheat (Triticum polonicum) were compared with Kamut wheat and two common wheat cultivars. Plants were analyzed to determine morphometric parameters (plant height, spike length, spike density, grain weight per spike and single kernel weight) and some chemical properties of grain: content of protein, ash, fat, crude fiber, minerals and mycotoxins. The studied genotypes produced a relatively weak response to infection with Fusarium culmorum which was expressed by a decrease in grain weight per spike and single kernel weight by 13 % and over 6 %, respectively. The grain of T. polonicum was characterized by a significantly higher protein and ash content than the grain of common wheat (by 19.8 and 23.7 %, respectively) and considerably higher concentrations of fat and dietary fiber than Kamut wheat (by 30.2 and 17.4 %, respectively). In comparison with common wheat, the grain of the examined genotypes was significantly more abundant in sulfur, magnesium and potassium as well as zinc, iron, copper and molybdenum. It contained significantly less aluminum and strontium. The inoculation led to a significant increase in fusariotoxin levels in the grain of all studied genotypes, and the average concentrations of the above metabolites were lower in the grain of T. polonicum than in Triticum aestivum. Polish wheat may constitute valuable genetic material for breeding new wheat varieties characterized by a high nutritive value and satisfactory resistance to FHB. 相似文献
252.
Rudolf M. Samisch 《The Journal of Horticultural Science and Biotechnology》2013,88(1):164-179
SummaryPluots are putative hybrids between plums (Prunus salicina Lindl.) and apricots (P. armeniaca L.). The capability to distinguish among plum and pluot cultivars is important in breeding and cultivation. We investigated the genetic diversity among 14 plums, 6 pluots and one plumcot representing commercial cultivars in California, with 28 microsatellite markers. We also tested seven apricot cultivars as a reference to ®nd evidence of apricot in the ancestry of pluots and plumcot. The parental material used in the original cross that produced the pluot and plumcot was not available. Of the 28 SSR markers, 25 were from sweet cherry (Prunus avium L.) and three from peach (Prunus persica L.). Approximately 80% of the cherry primers generated ampli®cation products in plum and pluots, showing transportability between these Prunus species. One to eight putative alleles per locus were displayed by the tested SSRs in plums and pluots. In plum and pluot samples a total of 100 alleles were identi®ed with an average of 4.3 alleles per primer combination. The SSR markers were successfully used for the discrimination of all tested cultivars. In pluots, 76 alleles were found in which 63 (83%) were speci®cally coming from plum, 9 (12%) were common in plum, pluots and apricot while no allele in the pluots was observed that was contributed from apricot. In plumcot, 49 alleles were observed in which 25 (51%) were from plum, 18 (36%) were speci®cally from apricot and 6 (12%) were common in plum, plumcot and apricot. Relationships among the 28 plum, pluot and apricot cultivars were represented by a dendrogram, constructed on the basis of 168 SSR markers. The dendrogram showed the plums and pluots form a cluster distinct from the apricots, with pluot cultivars interspersed among plum cultivars and more closely related to plum than to apricot. Plumcot made a separate branch and was placed between the plum and apricot cluster. These results suggest that the SSR markers are valuable tools for identi®cation of cultivars and diversity analyses in plum. 相似文献
253.
254.
Kerstin Scherr Hildegard Aichberger Rudolf Braun Andreas Paul Loibner 《European Journal of Soil Biology》2007,43(5-6):341
Various interactions occurring between organic chemicals and soil constituents participate in the determination of the fate of these pollutants, including their biodegradability. These relations need to be characterized in order to design and successfully implement a bioremediation application. In the present study, biodegradation of spiked and aged crude oil contamination in two dissimilar soils was related to their composition. GC-FID analysis of bulk soil samples as well as sand- and <63 μm fractions showed considerable differences in contaminant distribution and degradation behavior within these fractions. Whereas a freshly spiked silty soil showed reasonable degradation (51%), degradation was not significant after ageing. By contrast, a sandy soil was degraded by 25% (recently contaminated) and 19% (aged). Biodegradation occurred in the fine fraction only, with a comparably high content of organic carbon whereas hydrocarbon concentration remained constant in the sand fraction. This was correlated with sorption to the fine fraction where hydrocarbon concentrations were higher by over an order of magnitude compared to the sand fraction. Soil composition, biology and chemistry exert a pronounced influence on microbial degradation in respect to (i) contaminant availability and (ii) the structure and density of the microbial community. 相似文献
255.
Henryk A. Sobczuk Rudolf Plagge Ryszard T. Walczak Christian H. Roth 《植物养料与土壤学杂志》1992,155(2):157-163
Laboratory equipment was developed to measure nonsteady water potential and water content profiles in soil columns, with a high resolution in time and space. Moisture content was monitored using TDR-miniprobes and water potential was measured with microtensiometers. Gradients were applied by controlling the water potential at the bottom of the soil column during adsorption and desorption with the aid of a ceramic plate. The described experimental setup was designed specifically to determine effects of hysteresis on the water content/water potential and water potential/hydraulic conductivity relationships in undisturbed soil samples. In addition, an algorithm to process the data and to calculate the above mentioned relationships is presented. The algorithm includes the smoothing of data with Bezier functions before the calculation of the moisture retention curves and the conductivity functions. Results obtained from an albic E-horizon of a silty Luvisol are presented exemplarily to demonstrate the applicability of the proposed method in studying hysteresis effects. 相似文献
256.
257.
258.
Rudolf Hoffmann 《Forstwissenschaftliches Centralblatt》1940,62(1):20-21
Ohne Zusammenfassung 相似文献
259.
Rudolf Geiger 《Forstwissenschaftliches Centralblatt》1929,51(9):305-315
Ohne Zusammenfassung 相似文献
260.
Rudolf Getger und Hans Amann 《Forstwissenschaftliches Centralblatt》1931,53(23):809-819
Ohne Zusammenfassung 相似文献