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171.
Psittacine beak and feather disease (PBFD) is the most common viral disease of wild and captive psittacine birds. Here, we designed the first survey to investigate the existence of subclinical infections and the distribution of the causative agent named beak and feather disease virus (BFDV) inside the population of captive psittacine birds in Germany. DNA was isolated from feathers of 146 symptom-free birds from 19 different genera (all psittaformes) taken from 32 independent breeders from all over Germany. The presence of BFDV was analysed by performing polymerase chain reaction assays. Fifty-eight (39.2%) samples were found to be positive for BFDV. As expected, there was no significant predominance of one sex to be infected with BFDV.  相似文献   
172.
Mistakes in the results of residue analysis in vegetables and fruits based on samples Mistakes in the results of residue analysis can be separated into mistakes of sample-taking and those of analysing. The mistakes of sample-taking can be avoided when the sample represents the contents of the whole material which is to be analysed in percent. But this is an ideal case.In two examples, lettuce and leek, it is demonstrated that the pesticides are not in the same amount distributed at the different zones of the plant, the differences in the amounts can be, in the case of lettuce after application of quintozene, more than a fourtyfold amount or, in the case of leek after application of mancozeb, a twentyfold amount. Furthermore, the residues can be different from one plant individual to another demonstrated at cherries and radishes. The differences may be caused either by different application techniques or, for example, by different weight of individuals of the same species. Also, different habitus and growth can lead to different residues from one plant individual to another. When the plants take up the pesticides from the soil, a different pesticide distribution in the areas of the soil can also give rise to different residue values.Therefore, the man (engineer or analyst) who takes the samples, must take care for:1. taking the samples symmetrically from the field or from bottom to top of the trees2. chosing those plant individuals to give the labour sample which represent the average weight and the average habitus of the individuals. If plant individuals are analysed which take up the pesticides from the soil, the area from which the sample is derived, must be given.From all points shown, there is clear that a range of disseminating values which can be more than 100% must accounted in the values of residue analysis.  相似文献   
173.
大熊猫野外生存探讨(英文)   总被引:1,自引:0,他引:1  
李兆华 《林业研究》2001,12(1):59-62
濒危的大熊猫(Ailuropoda melanoleuca)是中国四川、甘肃和陕西省山区所特有的物种 。该种在20世纪70年代有2000多只。由于生境缩小、偷猎和竹林开花等原因所致,到20世纪 90年代,大熊猫种群的数量下降到不足1000只,且分离成32个亚种群。在过去的30多年中, 大量竹林开花和开花后死亡是大熊猫种群数量下降的主要原因。70年代,整个岷山的大熊猫 遭受饥荒,80年代蔓延到琼莱山,造成大熊猫大量死亡。大熊猫的生境被分离成很多小的“ 岛”,每个小的生存地只有几只熊猫,使得大熊猫的生存形式进一步恶化。小的、孤立的大 熊猫种群变的更加脆弱,很容易受到生境退化、自然灾害、疾病和近亲繁殖的威胁,从而导 致灭绝。因此,对于保护野生大熊猫来说,恢复大熊猫的生境并把大熊猫重新引回到它们的 历史生境中去,是一个重要的研究课题。  相似文献   
174.
Evaluating the accuracy and generality of a hybrid patch model   总被引:3,自引:0,他引:3  
Forest patch models have been used extensively to simulate vegetation development under current and changing environmental conditions. However, their physiological foundation is subject to criticism and recent validation experiments against long-term growth and yield data have shown major deficiencies in reproducing observed growth patterns of mixed-species forests. Here we describe the modified forest patch model PICUS Version 1.3, a model variant that couples the structurally detailed three-dimensional patch model PICUS Version 1.2 and the physiologically based stand-level production module of the 3-PG (Physiological Principles in Predicting Growth) model. The approach attempts to combine the ability of PICUS v1.2 to simulate forest dynamics on time scales relevant to forest succession with a simplified but successful production model based on the concept of radiation-use efficiency. We evaluated the hybrid model in a series of simulation experiments. Results indicated a realistic response to a climate sensitivity experiment: the response to environmental gradients was well captured both in terms of productivity on time scales of a rotation length and of forest succession over several hundreds of years. Testing against independent long- term growth and yield data revealed good correspondence between observed and predicted values of volume production and stand structure. Further model development should include a dynamic soil component to consider effects of nutrient cycling.  相似文献   
175.
MHC class II proteins present fragments of extra cellular antigen to stimulate CD4(+) T lymphocytes. Aim of this study was the detection of MHC class II antigens on different cutaneous cells in canine demodicosis. Histopathological and immunohistochemical examination of skin biopsies from 44 dogs with demodicosis is reported. The control group consisted of skin biopsies taken from 10 necropsied dogs without obvious skin lesions. The immunohistological assessment of the MHC class II expression revealed MHC class II proteins on different cell types of infiltrating inflammatory cells, i.e. APCs (antigen-presenting cells), macrophages, T lymphocytes and B lymphocytes. The plasma cells, however, only showed expression in 32 (73%) of 44 cases. Generally it was noticeable that most plasma cells but never all of them expressed MHC class II. Neutrophils, mast cells and eosinophils were MHC class II negative. Furthermore, in 39 biopsies (89%) from dogs with demodicosis MHC class II positive follicular keratinocytes were found. The control group did not show MHC class II expression on epithelial cells. Concerning the endothelial cells, a total of 25 biopsies (57%) showed MHC class II expression in which different vascular plexuses were affected by staining. This examination shows that MHC class II expression in the skin of dogs suffering form demodicosis is elevated. Especially the MHC class II expression by follicular keratinocytes seems to be conspicuous. We hypothesize that this is in association with the development and the maintenance of follicular inflammation.  相似文献   
176.
The proclamation of the “Soil of the Year” was made for the first time in Germany in 2005 on occasion of the World Soil Day. Chernozems were selected for this purpose. In this paper an overview of these groups of soils is given. Chernozems are concentrated in the drought region of Central Germany. A standard profile from the core area of Chernozems developed from loess is presented with comprehensive laboratory analysis. Chernozems developed primarily upon carbonatic loess substrates under summer‐dry climatic conditions in an open park‐like landscape with isolated forest stands. The development of Chernozems began as early as the late glacial period, and they were fully developed by the Atlantikum age. The far‐reaching, uniformly thick humus horizons indicate substrate differences in the loess cover, which are partly the result of bioturbation. Within Germany, Chernozems and Chernozem‐like soils make up approx. 3% of the surface area and 5% (approx. 11,000 km2) of the arable land. The results of the Static Fertilization Experiment in Bad Lauchstädt, founded in 1902, clarify the high value of Chernozem for biomass production and the environment. Each loss due to erosion or decrease in surface area reduces the fulfillment of soil ecological functions of the soils and is comparable to a loss of animal and plant species. Therefore, soil scientists and the results of soil research must be more comprehensively implemented for soil preservation, protection, and politics. For acceptance of these goals among the general public and the political‐decision makers, the campaign “Soil of the Year” should give some thought‐provoking impulses.  相似文献   
177.
Known or potential new fungal starter culture species such as Penicillium camemberti, P. roqueforti, P. nalgiovense, P. caseifulvum, and P. solitum have been cultivated on a cheese agar medium together with the common cheese contaminants P. commune, P. crustosum, P. discolor, P. atramentosum, and P. nordicum. Secondary metabolites were extracted and analyzed by HPLC-DAD and tested for cytotoxicity by using the MTT-cell culture assay. Metabolites such as cyclopiazonic acid, roquefortine C, and penitrem A, previously reported from cheese, were detected together with sclerotigenin, solistatin, meleagrin, oxaline, compactins, diaportins, chaetoglobosins, rugulovasines, verrucolones, anacines, verrucines, cyclopeptines, viridicatins, and viridic acid, all metabolites not previously reported from cheese. The two P. nalgiovense extracts were the most toxic in the MTT-cell culture test. These extracts contained diaportines together with a number of unknown compounds. P. roqueforti extracts were not toxic at all. Fungal extracts from the rest of the studied penicillia were toxic at levels between these two extremes.  相似文献   
178.
As a potential transmitter of bovine spongiform encephalopathy (BSE), tissue from bovine central nervous system (CNS) is not accepted in meat and meat products. Western blot analysis of the CNS marker myelin proteolipid protein (PLP) detects CNS contamination selectively and sensitively. In this study, a rapid dot blot assay using an anti-PLP antibody was developed to screen CNS contamination of meat and contact surfaces. The detection limit was 0.01% bovine brain in minced bovine muscle. When applied to a swab test, down to 0.5 mg of CNS tissue on meat or other surfaces was detectable. Other offal tissues or peripheral nerves did not interfere with the assay. The test allows a differentiation between mammalian and avian CNS but not among mammalian species. The swab test was applied immediately after slaughtering at several areas of the bovine head. CNS was not detectable at any region which may enter the food chain.  相似文献   
179.
Using the results of evaluation of Malus accessions during the last 20 years more than 15 new resistant apple cultivars were selected. The breeding aim was the combination of different kinds of resistance with good fruit quality. The best of these cultivars enclose resistance against Venturia inaequalis, Podosphaera leucotricha, Erwinia amylovora, Pseudomonas syringae, Panonychus ulmi and winterfrost. Different scab resistance sources (Vf, Vr, VA) found among the Malus species are combined in the most recent breeding lines.The new resistant Pillnitz apple cultivars ('Recultivars®') guarantee the possibility to reduce 80% and more of fungicide spraying in fruit growing and are very suitable for ecological and integrated fruit production. Four of these, 'Reanda', 'Rebella', 'Remo' and 'Rewena', are triple resistant to scab, mildew and fire blight and are good donors for breeding multiple resistance.  相似文献   
180.
Curcumin, the active constituent of Curcuma longa L. (family Zingiberaceae), has gained increasing interest because of its anti-cancer, anti-inflammatory, anti-diabetic, and anti-rheumatic properties associated with good tolerability and safety up to very high doses of 12 g. Nanoscaled micellar formulations on the base of Tween 80 represent a promising strategy to overcome its low oral bioavailability. We therefore aimed to investigate the uptake and transepithelial transport of native curcumin (CUR) vs. a nanoscaled micellar formulation (Sol-CUR) in a Caco-2 cell model. Sol-CUR afforded a higher flux than CUR (39.23 vs. 4.98 μg min?1 cm?2, respectively). This resulted in a higher Papp value of 2.11 × 10?6 cm/s for Sol-CUR compared to a Papp value of 0.56 × 10?6 cm/s for CUR. Accordingly a nearly 9.5 fold higher amount of curcumin was detected on the basolateral side at the end of the transport experiments after 180 min with Sol-CUR compared to CUR. The determined 3.8-fold improvement in the permeability of curcumin is in agreement with an up to 185-fold increase in the AUC of curcumin observed in humans following the oral administration of the nanoscaled micellar formulation compared to native curcumin. The present study demonstrates that the enhanced oral bioavailability of micellar curcumin formulations is likely a result of enhanced absorption into and increased transport through small intestinal epithelial cells.  相似文献   
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