全文获取类型
收费全文 | 75篇 |
免费 | 2篇 |
专业分类
林业 | 7篇 |
15篇 | |
综合类 | 4篇 |
农作物 | 4篇 |
水产渔业 | 4篇 |
畜牧兽医 | 27篇 |
园艺 | 15篇 |
植物保护 | 1篇 |
出版年
2023年 | 1篇 |
2019年 | 4篇 |
2018年 | 1篇 |
2017年 | 3篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2013年 | 11篇 |
2012年 | 2篇 |
2011年 | 4篇 |
2010年 | 2篇 |
2009年 | 3篇 |
2008年 | 5篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2005年 | 2篇 |
2004年 | 2篇 |
2003年 | 3篇 |
2002年 | 1篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1995年 | 2篇 |
1992年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 4篇 |
1979年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1971年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有77条查询结果,搜索用时 31 毫秒
11.
Gorana Rampazzo Todorovic Michael Stemmer Michael Tatzber Christian Katzlberger Heide Spiegel Franz Zehetner Martin H. Gerzabek 《植物养料与土壤学杂志》2010,173(5):662-670
Despite the importance of soil organic matter (SOM), very few long‐term data concerning soil organic‐C dynamics are available for calibrating and evaluating C models. The long‐term 14C‐turnover field experiment, established in 1967 in Fuchsenbigl, Lower Austria, offers the unique opportunity to follow the fate of labeled C under different crop‐management systems (bare fallow, spring wheat, crop rotation) over a period of more than 35 y. Compared with the crop‐rotation and spring‐wheat treatments, the decline of total organic C was largest in the bare‐fallow treatments, because no significant C input has occurred since 1967. Nonetheless, the decline was not as fast as predicted with the original RothC‐26.3‐model decomposition rate constants. In this work, we therefore calibrated the Roth‐C‐26.3 model for the Pannonian climatic region based on the field‐experiment results. The main adjustment was in the decomposition rate constant for the humified soil C pool (HUM), which was set to 0.009 instead of 0.02 y–1 as determined in the original Rothamsted field trial. This resulted in a higher HUM pool in the calibrated model because of a longer turnover period (111 vs. 50 y). The modeled output based on the calibrated model fitted better to measured values than output obtained with the original Roth‐C‐26.3‐model parameters. Additionally, the original decomposition rate constant for resistant plant material (RPM) was changed from 0.3 to 0.6 y–1 to describe the decomposition of 14C‐labeled straw more accurately. Application of the calibrated model (modified HUM decomposition rate) to simulate removal of crop residues showed that this can entail a long‐term decline of SOM. However, these impacts are strongly dependent on the crop types and on environmental conditions at a given location. 相似文献
12.
SummaryPhotoperiod and temperature control of flowering in a number of perpetual-flowering or everbearing strawberry cultivars of widely varying pedigree has been studied in controlled environments. Flower bud initiation in the cultivars ‘Flamenco’, ‘Ridder’, ‘Rita’ and ‘Rondo’ was significantly advanced by long-day (LD) conditions at temperatures of 15°C and 21ºC; while, at 27ºC, flowering took place under LD conditions only. Some plants of the seed-propagated F1-hybrid ‘Elan’, raised at 21°C, also flowered under short-day (SD) conditions at 27°C, but reverted to the vegetative state after a few weeks when maintained under these conditions. When vegetative plants growing in SD at 27°C were transferred to LD conditions at the same temperature, they consistently initiated flower buds and started flowering after about 4 weeks. At such a high temperature, flowering could thus be turned on and off by switching between SD and LD conditions. This applied to all the cultivars studied. Also the cultivar ‘Everest’, which was tested only at 21°C, produced similar results. Night interruption for 2 h was effective in bringing about the LD response. At 9°C, flowering was substantially delayed, especially in ‘Flamenco’ and, at this temperature, flowering was unaffected by photoperiod. Runner formation was generally promoted by high temperature and SD conditions, but the photoperiodic effect varied between experiments. We conclude that everbearing strawberry cultivars, in general, whether of the older European-type or the modern Californian-type originating from crosses with selections of Fragaria virginiana ssp. glauca, are qualitative (obligatory) LD plants at high temperature (27°C), and quantitative LD plants at intermediate temperatures. Only at temperatures below 10°C are these cultivars day-neutral. 相似文献
13.
SummaryPerpetual-flowering strawberry cultivars are commonly classified as photoperiodically day-neutral, even though early investigations demonstrated long-day (LD) regulation. An important reason for this inconsistency is that these freely flowering plants are difficult to establish in a true vegetative state, and experiments have therefore often been started using runner plants with pre-formed inflorescences. In order to circumvent this problem, we have used the perpetual-flowering F1-hybrid ‘Elan’ that is propagated by seed, and is thus not pre-conditioned by its earlier life history. The results demonstrated a marked quantitative LD response across a range of temperatures from 9° – 27°C. Seedlings were responsive to the LD stimulus at an early stage, and early flowering required LD exposure almost from germination. The critical daylength for the early flowering response was about 15 h at 18°C. Because of this threshold LD response, it is concluded that regulation of flowering is truly photoperiodic in nature, and not merely an effect of additional light. Flower development was also slightly advanced by LD conditions. Stolon formation was strongly enhanced by short-day conditions in combination with high temperature. Thus, not only flowering, but also runnering, was oppositely affected by photoperiod in ‘Elan’ compared with mono-flowering cultivars. The results are discussed in relation to the photoperiodic classification of strawberries. 相似文献
14.
Mitter Eduardo Kovalski dos Santos Graziely Cristina de Almeida Érica Janaína Rodrigues Morão Luana Galvão Rodrigues Heide Dayane Prates Corso Carlos Renato 《Water, air, and soil pollution》2012,223(2):765-770
With the development of the textile industry, there has been a demand for dye removal from contaminated effluents. In recent
years, attention has been directed toward various natural solid materials that are capable of removing pollutants from contaminated
water at low cost. One such material is sugarcane bagasse. The aim of the present study was to evaluate adsorption of the
dye Acid Violet Alizarin N with different concentrations of sugarcane bagasse and granulometry in agitated systems at different
pH. The most promising data (achieved with pH 2.5) was analyzed with both Freundlich and Langmuir isotherms equations. The
model that better fits dye adsorption interaction into sugarcane bagasse is Freundlich equation, and thus the multilayer model.
Moreover, a smaller bagasse granulometry led to greater dye adsorption. The best treatment was achieved with a granulometry
value lower than 0.21 mm at pH 2.50, in which the total removal was estimated at a concentration of 16.25 mg mL−1. Hence, sugarcane bagasse proves to be very attractive for dye removal from textile effluents. 相似文献
15.
Summary Potato virus S was eliminated from systemically infected stem cuttings of five potato cultivars after three passages in nutrient
media containing 0.003% of the synthetic riboside ribavirin (Virazole). Treatment effects could be detected after only two
passages which also revealed differences in cultivar response. Treated plants transferred to ribavirin-free culture media
and to soil remained PVS-free.
This simple method is less time-consuming than the usual meristem (axillary) tip culture procedures combined with chemotherapy
or heat treatment. 相似文献
16.
Vaccination of three commercial broiler-breeder flocks at 15 weeks old with viral arthritis/tenosynovitis via the drinking water resulted in serologic conversion of two flocks to agar-gel-precipitin (AGP)-positive, while the third flock was still AGP-negative at 24 weeks, but was AGP-positive at 30 weeks old, presumably as a result of natural exposure. Progeny from the two successfully vaccinated breeder flocks remained free of clinical viral arthritis/tenosynovitis and had average condemnation rates of 0.99%. In contrast, six hatches of progeny from the third breeder flock experienced clinical viral arthritis/tenosynovitis and average condemnation rates of 3.64%. 相似文献
17.
O. M. Heide 《The Journal of Horticultural Science and Biotechnology》2013,88(5):433-442
SummaryRecent research on how the structure and physiological development of red raspberry (Rubus idaeus L.) plants are controlled by genotype and the climatic environment is reviewed. Some older work, especially on plant structure relations, is also included. Physiological differences between annual- and biennial-fruiting plant types are highlighted. One major difference is the different requirements for flower formation. While biennial-fruiting cultivars have an absolute low temperature (≤ approx. 15°C) requirement for floral initiation, annual-fruiting cultivars readily initiate floral primordia at temperatures as high as a constant 30°C. Also, while biennial-fruiting cultivars are facultative short-day plants with a critical photoperiod of 15 h at intermediate temperatures, flowering is promoted by long photoperiods in at least some annual-fruiting cultivars. However, the essential difference that determines whether the shoot life-cycle becomes annual or biennial is that, in biennial-fruiting genotypes, floral initiation is linked to the induction of bud dormancy; whereas, in annual-fruiting cultivars, floral initiation is followed by direct flower development. Although this is genetically determined, it is a plastic trait that is subject to modification by the environment. Thus, at low temperatures and under short photoperiods, the majority of initiated buds also enter dormancy in annual-fruiting cultivars, with tip-flowering as a result. Practical applications are discussed, and it is concluded that our present physiological knowledge-base provides excellent opportunities for the manipulation of raspberry crops for out-of-season production and high yields. It also provides a firm platform for further exploration of the underlying molecular genetics of plant structures and response mechanisms. 相似文献
18.
Low temperature, but not photoperiod, controls growth cessation and dormancy induction and release in apple and pear 总被引:8,自引:0,他引:8
In contrast to most temperate woody species, apple and pear and some other woody species of the Rosaceae family are insensitive to photoperiod, and no alternative environmental seasonal signal is known to control their dormancy. We studied growth and dormancy induction in micropropagated plants of four apple (Malus pumila Mill.) and one pear (Pyrus communis L.) commercial rootstock cultivars in controlled environments. The results confirm that growth cessation and dormancy induction in apple and pear are not influenced by photoperiod, and demonstrate that low temperature (< 12 degrees C) consistently induces both processes, regardless of photoperiodic conditions. Successive stages of the autumn syndrome (growth cessation, formation of bud scales and winter buds, leaf senescence and abscission, and dormancy induction) occurred in response to low temperature. Long days increased internode length at higher temperatures, but had no significant effect on leaf production in any of the cultivars. Chilling at 6 or 9 degrees C for at least 6 weeks (about 1000 h) was required for dormancy release and growth resumption, whereas treatment at 12 degrees C was marginally effective, even after 14 weeks of exposure. We are thus faced with the paradox that the same low temperature conditions that induce dormancy are also required for dormancy release in these species. 相似文献
19.
When the exotic Acer platanoides L. (Norway maple) and the native A. saccharum Marsh. (sugar maple) grow together in the understories of urban Quercus forests in the eastern USA, average annual height growth increments are nearly twice as large in A. platanoides as in A. saccharum, 19.26 +/- 3.22 versus 10.01 +/- 1.69 cm. We examined several ecophysiological mechanisms that might be associated with the superior invasive ability and growth of A. platanoides in two urban oak forests in Pennsylvania. Leaf longevity was 12 days greater in A. platanoides than in A. saccharum. In addition, leaf mass/leaf area ratio was greater in A. platanoides than in A. saccharum (2.67 +/- 0.03 versus 2.32 +/- 0.02 mg cm(-2)); however, leaf thickness was significantly lower in A. platanoides than in A. saccharum suggesting that A. platanoides contains more dense palisade and mesophyll cell layers than A. saccharum. Field net photosynthesis (mass basis) and photosynthetic light response curves (area basis) indicated significantly greater carbon assimilation, and nitrogen and phosphorus use efficiencies in A. platanoides than in A. saccharum. Acer platanoides also exhibited higher water use efficiency than A. saccharum (0.88 +/- 0.12 versus 0.32 +/- 0.09 mmol CO(2) mol(-1) H(2)O). Acer platanoides exhibited significantly lower osmotic potentials than A. saccharum, but a similar relative water content at zero turgor. We conclude that A. platanoides utilizes light, water and nutrients more efficiently than A. saccharum. 相似文献
20.
"Marble spleen disease" of chickens was diagnosed in 22-week-old chickens. Total mortality was 8.9%. Deaths occurred over a period of 2 months. Gross lesions included pulmonary congestion, splenomegaly, hepatomegaly, and congestion of egg follicles. Microscopic lesions included pulmonary congestion and edema, and reticuloendothelial cell hyperplasia of the spleen with concurrent white-pulp necrosis and lymphocyte depletion. The pulmonary lesions were of sufficient intensity to have caused the death of fatally affected birds. Many of the hyperplastic reticuloendothelial cells contained basophilic intranuclear inclusions similar to those that characterize hemorrhagic enteritis of turkeys, marble spleen disease of pheasants, and adenovirus group II splenomegaly of chickens. These characteristic lesions, plus serologic identification of the causal virus, indicate that "marble spleen disease" caused by avian group II adenovirus was affecting the flock under study. This appears to be the first report of death of chickens due to pulmonary congestion and edema caused by spontaneous infection with avian group II adenovirus. 相似文献