全文获取类型
收费全文 | 351篇 |
免费 | 21篇 |
国内免费 | 2篇 |
专业分类
林业 | 76篇 |
农学 | 19篇 |
基础科学 | 1篇 |
96篇 | |
综合类 | 26篇 |
农作物 | 12篇 |
水产渔业 | 10篇 |
畜牧兽医 | 113篇 |
园艺 | 8篇 |
植物保护 | 13篇 |
出版年
2023年 | 3篇 |
2021年 | 9篇 |
2020年 | 7篇 |
2018年 | 3篇 |
2017年 | 10篇 |
2016年 | 11篇 |
2015年 | 4篇 |
2014年 | 14篇 |
2013年 | 26篇 |
2012年 | 18篇 |
2011年 | 14篇 |
2010年 | 11篇 |
2009年 | 10篇 |
2008年 | 23篇 |
2007年 | 15篇 |
2006年 | 17篇 |
2005年 | 16篇 |
2004年 | 12篇 |
2003年 | 14篇 |
2002年 | 11篇 |
2000年 | 9篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 11篇 |
1989年 | 3篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1969年 | 2篇 |
1949年 | 2篇 |
1936年 | 2篇 |
1934年 | 2篇 |
1932年 | 2篇 |
1931年 | 4篇 |
1929年 | 2篇 |
1928年 | 3篇 |
1925年 | 2篇 |
1918年 | 4篇 |
1917年 | 3篇 |
1916年 | 2篇 |
1908年 | 2篇 |
排序方式: 共有374条查询结果,搜索用时 203 毫秒
101.
102.
Zidorn C Jöhrer K Ganzera M Schubert B Sigmund EM Mader J Greil R Ellmerer EP Stuppner H 《Journal of agricultural and food chemistry》2005,53(7):2518-2523
A dichloromethane extract of root celery yielded falcarinol, falcarindiol, panaxydiol, and the new polyacetylene 8-O-methylfalcarindiol. The structure of the new compound was established by one- and two-dimensional (1D and 2D) NMR, mass spectrometry, and optical rotation data. Nonpolar extracts of roots and bulbs of carrots, celery, fennel, parsley, and parsnip were investigated for their content of polyacetylenes by high-performance liquid chromatography with diode array detection (HPLC-DAD). All five species contained polyacetylenes, although carrots and fennel only in minor amounts. Additionally, the cytotoxicity of the four polyacetylenes against five different cell lines was evaluated by the annexin V-PI assay. Falcarinol proved to be the most active compound with a pronounced toxicity against acute lymphoblastic leukemia cell line CEM-C7H2, with an IC(50) of 3.5 micromol/L. The possible chemopreventive impact of the presented findings is discussed briefly. 相似文献
103.
Kleinova M Zöllner P Kahlbacher H Hochsteiner W Lindner W 《Journal of agricultural and food chemistry》2002,50(17):4769-4776
A group of five heifers were fed for 84 days with 2 kg of zearalenone-contaminated oats (1370 microg/kg) resulting in an average daily intake of 2740 microg of zearalenone per animal. In a parallel experiment five heifers were implanted with two 25 mg zeranol pellets, one at the beginning of the study and one after 42 days, and fed with 2 kg of "blank" control oats (79 microg/kg, daily intake = 158 microg). A third group of five animals were also fed with 2 kg of "blank" oats and served as control. Urine samples of all animals were collected every 5-6 days during the whole period of the study. Animals of all three groups were killed 84 days after the beginning of the feeding study. Tissue samples (back, femoral region, liver, and residues of implanted pellets) were taken during post-mortem investigations. The content of zearalenone and zeranol and their metabolites in urine and tissue samples was established by an analytical method combining solid-phase extraction and high-performance liquid chromatography-tandem mass spectrometry. Urinary excretion rates of zeralenone and zeranol were calculated from these results. 相似文献
104.
Hermann Buerstmayr Michael Stierschneider Barbara Steiner Marc Lemmens Michaela Griesser Eviatar Nevo Tzion Fahima 《Euphytica》2003,130(1):17-23
Head blight of wheat (FHB, scab) caused by Fusarium spp. has been associated with yield and quality losses in many wheat-growing regions. In tetraploid wheat sources of resistance
are scarce. In the search for novel sources of resistance, 151 Triticum dicoccoides genotypes, originating from 16 habitats in Israel and one habitat in Turkey together with several control genotypes, were
evaluated for reaction to fungal spread (Type II resistance) in replicated greenhouse experiments. Significant genetic diversity
was found among the tested genotypes, the broad sense heritability for Type II FHB resistance was 0.71. Most of the tetraploid
accessions were highly susceptible, only a few showed moderate resistance. Among the eight T. dicoccoides lines with the lowest relative infection rates, five originated from the Mt. Gerizim population, and three from the Mt. Hermon
population. None of the
T. dicoccoides lines reached the level of resistance present in the common wheat cultivar Sumai3.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
105.
Stefan Fleck Inga Mölder Mascha Jacob Tobias Gebauer Hermann F. Jungkunst Christoph Leuschner 《Annals of Forest Science》2011,68(7):1173-1185
Introduction
Sight-based field measurements of tree crown projection area and canopy height are common praxis in forest science but difficult to validate. We quantified their measurement errors based on the virtual representation of an 11-species old-growth forest provided by high-resolution terrestrial LIDAR (light detection and ranging) measurements. 相似文献106.
Michelitsch A Rückert U Rittmannsberger A Seger C Strasser H Likussar W 《Journal of agricultural and food chemistry》2004,52(6):1423-1426
A simple and accurate differential pulse polarographic method has been developed for the determination of oosporein in the culture broth of the fungus Beauveria brongniartii. This hydroxybenzoquinone derivative is the only major secondary metabolite secreted by this entomopathogenic fungus, which is used as biological pest control agent (BCA) against Melolontha melolontha larvae. It can be found in the host organism as well as in the formulated product. The polarographic behavior of oosporein was examined in various buffer systems over the pH range 3-10. In Britton-Robinson buffer/methanol solution (3:7 v/v, pH 5.5) the differential pulse polarograms exhibited reproducible peaks at E(p) = -0.18 V vs silver/silver chloride/potassium chloride (3 M). Under these conditions, a plot of peak height vs concentration of oosporein was found to be linear over the range 5.9 x 10(-)(7) to 2.5 x 10(-)(5) M (0.18-7.74 microg mL(-)(1); r = 0.9998). The detection limit was calculated to be 54 ng mL(-)(1). To evaluate the concentration of oosporein, the standard addition method was applied. The analysis of oosporein in the culture broth led to a mean value of 524.9 microg mL(-)(1) broth with a relative standard deviation (S(rel)) of +/-2.6%. The proposed polarographic method is accurate, not time-consuming, and it is of low cost because no separation steps are necessary. 相似文献
107.
Hermann Bauwe 《Genetic Resources and Crop Evolution》1990,38(1):39-48
Zusammenfassung Nach einem kurzen historischen Überblick über wesentliche Entdeckungen auf dem Gebiet der Photosyntheseforschung werden Fragen der Regulation der Photosynthese höherer Pflanzen behandelt. Dabei wurden vor allem die an der Ribulose-1,5-biphosphat Carboxylase/Oxygenase angreifenden Regulationsprinzipien berücksichtigt.
相似文献
Molecular regulation of photosynthetic processes
Summary Following a short survey on the history of photosynthesis research some of the main principles of photosynthetic regulation are discussed. Especially, those mechanisms are considered which are involved in the regulation of ribulose-1,5-bisphosphate carboxylase/oxygenase.
, . ¶rt; -1,5- / .
相似文献
108.
Zusammenfassung Ein mathematisches Verfahren wird beschrieben, mit dessen Hilfe auf mögliche, durch Translokationen bedingte Paarungspräferenzen der Chromosomen in der Meiose bei Autotetraploiden geschlossen werden kann. Bei Gerste konnte mit Hilfe von einfachen und multiplen Translokationen im duplex-heterozygoten Zustand gezeigt werden, daß die Strukturumbauten offenbar in gewissen Grenzen zu präferenzieller Paarung der an den Translokationen beteiligten Chromosomen führten.
Herrn Prof. Dr. Drs. h. c.Hans Stubbe zum 75. Geburtstag gewidmet. 相似文献
Preferential Pairing of the Chromosomes of Autotetraploid Barley — a Mathematical Model
Summary A mathematical method is described which can be used for ascertaining possible effects of translocations on chromosome pairing during meiosis in autotetraploids. Using single and multiple translocations in duplex-heterozygous condition in barley, it has been shown that the structural rearrangements apparently resulted in a certain amount of preferential pairing of the chromosomes involved in the interchanges.
.
, , . - , , , .
Herrn Prof. Dr. Drs. h. c.Hans Stubbe zum 75. Geburtstag gewidmet. 相似文献
109.
Shoots of spruce (Picea abies (L.) Karst.) seedlings grown in solution culture were fumigated with sulfur dioxide or ozone, or with a combination of both for 60 days. Dry weights of the shoots exposed to O3 and SO2/O3 were increased over the controls. Uptake rates of calcium, magnesium, potassium and nitrate from the nutrient solutions were altered in dependence on fumigation, time of exposure and stage of plant development. Uptake rates of all ions by the seedlings fumigated with SO2 first increased, but later on decreased as compared to the control. Fumigation with O3, or O3 in combination with SO2 affected uptake of the various nutrients differently. The effects of the pollutants on the concentrations of calcium and magnesium in the various parts of the seedlings indicate that the changes are not only due to altered water and ion uptake but may be related to various effects in ion transport and plant metabolism. 相似文献
110.
Zöllner P Jodlbauer J Kleinova M Kahlbacher H Kuhn T Hochsteiner W Lindner W 《Journal of agricultural and food chemistry》2002,50(9):2494-2501
The content of zearalenone and its metabolites in urine and tissue samples from pigs fed zearalenone-contaminated oats was established by analytical methods combining solid-phase extraction cleanup of the samples with highly selective liquid chromatography-mass spectrometry (LC-MS)/MS detection. Investigation of the urine samples revealed that approximately 60% of zearalenone was transformed in vivo to alpha-zearalenol and its epimer beta-zearalenol in a mean ratio of 3:1. Zeranol and taleranol as further metabolites could only be detected in trace amounts. Zearalanone was identified at considerable concentrations, though only in a couple of samples. In contrast, liver samples contained predominantly alpha-zearalenol, and to a minor extent beta-zearalenol and zearalenone, with a mean ratio of alpha-/beta-zearalenol of 2.5:1, while zeranol, taleranol, or zearalanone could not be identified in any of the investigated samples. The degree of glucoronidation was established for zearalenone as 27% in urine and 62% in liver; for alpha-zearalenol as 88% in urine and 77% in liver; and for beta-zearalenol as 94% in urine and 29% in liver. Analyses of muscle tissue revealed relatively high amounts of nonglucuronidated zeranol and alpha-zearalenol together with traces of taleranol and zearalenone, indicating that the metabolism of zearalenone and its metabolites is not restricted to hepatic and gastrointestinal metabolic pathways. 相似文献