全文获取类型
收费全文 | 319篇 |
免费 | 10篇 |
专业分类
林业 | 17篇 |
农学 | 4篇 |
97篇 | |
综合类 | 20篇 |
农作物 | 23篇 |
水产渔业 | 1篇 |
畜牧兽医 | 143篇 |
园艺 | 5篇 |
植物保护 | 19篇 |
出版年
2024年 | 1篇 |
2023年 | 7篇 |
2022年 | 3篇 |
2021年 | 7篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2017年 | 9篇 |
2016年 | 5篇 |
2015年 | 8篇 |
2014年 | 15篇 |
2013年 | 20篇 |
2012年 | 25篇 |
2011年 | 35篇 |
2010年 | 9篇 |
2009年 | 10篇 |
2008年 | 20篇 |
2007年 | 21篇 |
2006年 | 20篇 |
2005年 | 11篇 |
2004年 | 16篇 |
2003年 | 15篇 |
2002年 | 16篇 |
2001年 | 5篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1983年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1971年 | 1篇 |
1969年 | 2篇 |
1966年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有329条查询结果,搜索用时 15 毫秒
91.
Kerstin?Hund-RinkeEmail author Monika?Lindemann Markus?SimonEmail author 《Journal of Soils and Sediments》2005,5(4):233-239
Goal, Scope and Background The earthworm avoidance test is a sensitive screening test. Currently, two test designs, a two-chamber system and a six-chamber
system, are under standardization. In the scope of the present study, the two test systems are compared. To assess the results,
two procedures are applied, which are based on a threshold value and a statistical method. Moreover, the sensitivity of the
avoidance test is compared with the sensitivity of the reproduction test.
Methods The avoidance behaviour of E. fetida towards five chemicals (Cd, Cu, PCP, TBT, TNT) was tested in a sandy and a loamy soil.
The ecotoxicological test was performed according to the draft guideline ISO/DIS 17512-1. The results were compared with the
number of offspring determined in the reproduction test carried out according to ISO 11268-2.
Results and Discussion The results demonstrate that the avoidance behaviour towards organic chemicals and heavy metals is a suitable screening method
showing first tendencies of a chemical's effects on the habitat function of soils. Effects caused by chemical substances become
visible at low concentrations and within short test periods. The sensitivity of the reproduction test and the avoidance test
is principally comparable; in some cases, the avoidance test showed more sensitive reactions. The dose-response-relationships
were more pronounced in the two-chamber test than in the six-chamber-system.
Recommendation and Outlook The two-chamber-system proved to be more feasible than the six-chamber-system. As the sensitivity of the avoidance test and
the reproduction test is comparable, the avoidance test can be considered as a suitable screening test as well. A possible
field of application may be the selection of soil samples for which the reproduction assay seems necessary. To assess contaminated
or remediated soils, the earthworm reproduction test is recommended as an indicator for the habitat function of the soils.
To reduce costs, the labour intensive reproduction test could be largely replaced by the avoidance test in performing the
earth-worm reproduction test only for relevant samples.
Before the Draft International Standard of the guideline will be adopted as an ISO Guideline, there will be sufficient time
left to gain further international experience required to finalize the method. 相似文献
92.
Fandohan P Gbenou JD Gnonlonfin B Hell K Marasas WF Wingfield MJ 《Journal of agricultural and food chemistry》2004,52(22):6824-6829
Essential oils extracted by hydrodistillation from local plants in Benin, western Africa, and oil from seeds of the neem tree (Azadirachta indica) were evaluated in vitro and in vivo for their efficacy against Fusarium verticillioides infection and fumonisin contamination. Fumonisin in corn was quantified using a fluorometer and the Vicam method. Oils from Cymbopogon citratus, Ocimum basilicum, and Ocimum gratissimum were the most effective in vitro, completely inhibiting the growth of F. verticillioides at lower concentrations over 21 days of incubation. These oils reduced the incidence of F. verticillioides in corn and totally inhibited fungal growth at concentrations of 8, 6.4, and 4.8 microL/g, respectively, over 21 days. At the concentration of 4.8 microL/g, these oils did not affect significantly fumonisin production. However, a marked reduction of fumonisin level was observed in corn stored in closed conditions. The oils adversely affected kernel germination at 4.8 microL/g and therefore cannot be recommended for controlling F. verticillioides on stored corn used as seeds, when used at this concentration. The oil of neem seeds showed no inhibitory effect but rather accelerated the growth of F. verticillioides. 相似文献
93.
Valerien Zinsou Kerstin Wydra Bonaventure Ahohuendo Lukas Schreiber 《Euphytica》2006,149(1-2):189-198
Summary To elucidate the role of leaf surface structures as first barriers to confer resistance to bacterial blight, leaf stomata and their occlusion with leaf waxes were studied in cassava genotypes. For the first time, cassava leaf waxes were quantitatively and qualitatively analysed. Comparing the susceptible and resistant standard genotypes BEN86052 and TMS30572, respectively, the total quantity of triterpenes was significantly higher in the resistant genotype, grown in three ecozones of Benin. In cuticular leaf waxes of seven cassava genotypes the triterpenes beta amyrins, epi-taraxerol, taraxerone and taraxerol were dominant constituents across genotypes, and alkanes (C25-C33) and acids (C30 and C32) occurred in minor concentrations. Comparing seven genotypes, no clear relation between resistance or ecozones and total quantities of the major wax constituents was observed. Only the highly resistant genotype TMS30572 showed high triterpene levels irrespective of ecozone. Scanning electron-microscopy revealed a regular distribution of waxes at the abaxial leaf surface, covering and occluding stomatal pores of susceptible and resistant genotypes, while on the adaxial leaf surface waxes were in form of crystalloids and did not occlude the stomata. The number of stomata on the abaxial surfaces was about 7–11 fold higher than on the adaxial surfaces, where stomata were located along the midrib and major veins. No significant differences in stomata number were observed between genotypes varying in resistance to bacterial blight. It is suggested, that stomata on the adaxial surface might be portals of entry for the bacteria. 相似文献
94.
95.
Fruzsina?Szira Andreas?B?rner Kerstin?Neumann Khalil?Zaynali?Nezhad Gábor?Galiba András?Ferenc?BálintEmail author 《Euphytica》2011,178(3):373-391
To improve our knowledge on the genetic control of drought tolerance, the Oregon Wolfe Barleys (OWB), considered as a reference
population in genetic mapping, were subjected to various types of water deficit. Overall, when investigating numerous environments
and replications, 40 QTLs were identified in three developmental stages. Based on these loci five QTL clusters were separated,
which affect various drought-related traits in at least two developmental stages. Several candidate genes were identified
for each QTL cluster using an expressed sequence tag (EST)-based map with high marker density. The putative role of the candidates
in drought tolerance is discussed. The phenotypic effect of three of the five candidate genes was also tested on 39 barley
landraces and cultivars and a significant relationship was found between the allelic composition of these genes and yield
production under stress conditions. This study presents a relevant example of the use of reliable QTL data in the candidate
gene approach, while also demonstrating how the results could be practically utilized in marker-assisted selection (MAS). 相似文献
96.
97.
Plant roots compete for nutrients mineralised by the decomposer community in soil. By affecting microbial biomass and activity Collembola influence the nutrient availability to plants. We investigated the effect of Collembola (Protaphorura fimata Gisin) on growth and competition between of two plant species, Cirsium arvense L (creeping thistle) and Epilobium adnatum Griseb. (square-stemmed willow herb), in a laboratory experiment. Two seedlings of each plant species were planted in rhizotrons either in combination or in monoculture (intra- and interspecific competition). Interspecific competition strongly reduced total biomass of C. arvense whereas E. adnatum suffered most from intraspecific competition. Collembola neither affected the competitive relationship of the two plant species nor shoot and root biomass. Although Collembola did not affect total root biomass they influenced root morphology of both plant species. Roots grew longer and thinner and had more root tips in presence of Collembola. Root elongation is generally ascribed to the exploitation of nutrient rich patches in soil. We hypothesise that changes in root morphology in presence of Collembola are due to Collembola-mediated changes in nutrient availability and distribution. 相似文献
98.
99.
Persson E Sjöholm I Nyman M Skog K 《Journal of agricultural and food chemistry》2004,52(25):7561-7566
The influence of the addition of carbohydrates with different physicochemical properties on weight loss and formation of heterocyclic amines (HAs) during the frying of beef burgers was examined. Furthermore, the capability of carbohydrates to bind HAs was tested. Beef burgers containing 1.5% NaCl and 0.3% tripolyphosphate (reference), with the addition of 1.5% carbohydrate, were fried for 5 min at 200 degrees C in a double-sided pan fryer. The beef burgers were analyzed for HAs with solid phase extraction and liquid chromatography/mass spectrometry. 2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx), 2-amino-1-methyl-6-phenyl-imidazo[4,5-b]pyridine (PhIP), and 9H-pyrido[3,4-b]indole (Norharman) were detected in all of the beef burgers. The addition of carbohydrates affected both the weight loss and the formation of HAs during cooking. The formation of HAs could be correlated to depend on both the weight loss and the type of the added carbohydrate. Of the 11 different carbohydrates tested, raw potato starch was most capable of inhibiting the formation of HAs, while potato fiber gave the lowest weight loss and a comparably low amount of PhIP. Wheat bran and potato fiber were found to reversibly bind HAs. It is concluded that adding small amounts of certain carbohydrates may be a simple and effective way of reducing the amount of HAs and can easily be applied in households and commercial preparations of beef burgers. 相似文献
100.
Natural variations of precursors in pig meat affect the yield of heterocyclic amines--effects of RN genotype, feeding regime, and sex 总被引:3,自引:0,他引:3
Olsson V Solyakov A Skog K Lundström K Jägerstad M 《Journal of agricultural and food chemistry》2002,50(10):2962-2969
Pig meat shows natural variations in the concentrations of precursors of heterocyclic amines (HCAs), which may affect formation of HCAs in cooked pig meat. To study this, 26 pigs with an inherent genetic variation (carriers and noncarriers of the RN(-) allele) were subjected to different feeding regimes (conventional feed compared with feed composed according to organic standards). In addition, the effect of sex (castrated males or females) was considered when assessing chemical and technological meat quality parameters. Concentrations of precursors of HCAs, i.e., creatine, residual glycogen, dipeptides, and free amino acids, were analyzed in the raw meat, and the levels of some HCAs (4,8-DiMeIQx, MeIQx, PhIP, harman, and norharman) were then determined in fried meat patties prepared from these pigs. The RN genotype most affected technological meat quality parameters and the level of precursors of HCAs, especially the level of residual glycogen, where carriers of the RN(-) allele showed levels four times as high as those of noncarriers (75.3 +/- 2.6 compared with 17.2 +/- 2.4 micromol/g meat, least-squares means +/- SE). The increased level of residual glycogen resulted in about 50% lower amounts of total mutagenic HCAs in cooked meat compared with cooked meat from normal pigs. Fried meat from carriers of the RN(-) allele obtained darker crust color than meat from noncarriers. Feeding regime and sex did not significantly affect the chemical composition of the meat or the formation of HCAs. 相似文献