全文获取类型
收费全文 | 273篇 |
免费 | 16篇 |
专业分类
林业 | 24篇 |
农学 | 4篇 |
基础科学 | 2篇 |
57篇 | |
综合类 | 44篇 |
农作物 | 11篇 |
水产渔业 | 23篇 |
畜牧兽医 | 81篇 |
园艺 | 8篇 |
植物保护 | 35篇 |
出版年
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 4篇 |
2020年 | 5篇 |
2019年 | 11篇 |
2018年 | 6篇 |
2017年 | 6篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 3篇 |
2013年 | 8篇 |
2012年 | 17篇 |
2011年 | 26篇 |
2010年 | 13篇 |
2009年 | 14篇 |
2008年 | 13篇 |
2007年 | 18篇 |
2006年 | 17篇 |
2005年 | 18篇 |
2004年 | 16篇 |
2003年 | 12篇 |
2002年 | 18篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1957年 | 1篇 |
1944年 | 1篇 |
1941年 | 1篇 |
排序方式: 共有289条查询结果,搜索用时 15 毫秒
101.
Cuny Damien Van Haluwyn Chantal Shirali Pirouz Zerimech Fharid Jérôme Laurence Haguenoer Jean Marie 《Water, air, and soil pollution》2004,152(1-4):55-69
The purpose of this research is to present toxic effects of some heavy metals (cadmium, lead and zinc) on lichen physiology. In the North of France, those metals are concentrated for example in industrial polluted soils near metallurgic plants and waste dumps. Our investigations were conducted on Diploschistes muscorum (Scop.) R. Sant, a terricolous lichen growing on previously quoted soils as well as on non-contaminated ones. Different stress parameters were investigated as potassium leakage – which is related to the loss of membrane integrity – and oxidative stress through following parameters: malondialdehyde (MDA), glutathione (GSH) and superoxide dismutase (SOD). It seems, therefore, that heavy metals induce oxidative stress in this lichen, in which we found membrane damage and enhancement of SOD activity and GSH concentrations. With regard to very high concentrations of Cd, Pb and Zn, a resistance involving antioxidant mechanisms limits the expected damage. Those mechanisms involve GSH, SOD as well as secondary metabolites, which have this resistance property. This study is a first step of investigation to use – in the future– physiological parameters as tool for environment assessment. 相似文献
102.
Laurence M. Saint-Pierre Jamie M. Burkitt-Creedon Flavio H. Alonso Matthew K. Wun 《Journal of veterinary diagnostic investigation》2022,34(6):968
A 7-y-old male Labrador Retriever dog was presented because of acute onset of dark-colored urine after a hunting session the day prior. Moderate hemoglobinemia was observed, associated with transient hemoglobinuria and hematuria with no concurrent evidence of underlying urinary tract disease. The patient’s clinical signs resolved within 36 h post-exercise without specific treatment. The concurrent occurrence of exertional hemolysis and hematuria in a dog is uncommon; these conditions are commonly reported separately in human athletes. 相似文献
103.
Anatomy, physiology and pathology of the amniotic and allantoic compartments in the sheep and cow 总被引:1,自引:0,他引:1
In both cows and sheep the allantoic fluid is confined to 2 sacs connected by a flattened isthmus, one in the non-pregnant horn and one in the upper part of the pregnant horn. The chorion encloses the amniotic and allantoic compartments, forming the amniochorion and chorioallantois, respectively. In the last third of gestation the compositions of both amniotic and allantoic fluids differ substantially from each other and from those of foetal urine, and maternal and foetal plasma. There is less variation in composition than in volume for a given gestational age. Abnormalities of volume are more common in cows than sheep, and hydrallantois is more common than hydramnois. Data obtained from both physiological experiments and pathological cases suggest that the foetal membranes play an important role in the regulation of composition and volume of foetal fluids. Evidence is presented that the permeability of the membranes to various solutes, as well as their capacity to produce and respond to a number of hormones, can affect the foetal fluid composition and/or volume. Progesterone, oestrogens and prolactin are some of the hormones known to affect foetal fluids. Foetal adrenal insufficiency has been associated with hydramnios implying a lack of hormones from this gland in this disease. The changes in allantoic fluid composition from normal to that closely resembling maternal/foetal extracellular fluid, in hydrallantois, suggests an alteration of membrane function as an aetiology and the continued production of fluid, after removal of the foetus in some cases, favours this hypothesis. 相似文献
104.
105.
Trials in 1975 and 1976 showed that deposit levels of the fungicide binapacryl, on the leaves of bush trees of Cox's Orange Pippin (Cox) after mist blower spraying, varied inversely with tree spread. Deposit levels were measured on young mildew-susceptible leaves from a well-sprayed zone around the periphery of the tree canopy at a height of 1.5 m. Low deposit levels in large, dense trees were associated with poor mildew control. Leaves from the smallest trees had deposit levels considerably greater than those found for larger trees (in another nearby orchard) which had adequate mildew control. Fungicide deposit levels on leaves from up to five different zones of trees of three different sizes (the largest trees were of the variety Bramley's Seedling) were measured in 1977. The smallest trees had significantly higher deposit levels than the larger trees in the lower centre and lower outside zones of the trees, whereas both orchards of Cox had the same (commercially acceptable) level of mildew infection at the end of the season. Leaves from zones less accessible to spray had lowerdeposit levels than those nearer the sprayer. 相似文献
106.
Suraud V Olivier M Bodier CC Guilloteau LA 《Veterinary immunology and immunopathology》2007,115(3-4):239-250
The differential expression of homing receptors (HR) and complementary vascular addressins was studied in T and B lymphocytes from ovine tonsils and draining lymph nodes (LN) in uninfected and Brucella melitensis-infected sheep. In uninfected sheep, CD4+CD25+ T cells expressed proportionally more L-selectin and beta1 integrin than beta7 integrin in pharyngeal and palatine tonsils and in parotid LN (PLN), retropharyngeal LN (RLN) and the peripheral prescapular LN (PSLN). In contrast, memory CD4+CD45RA- T cells expressed an equivalent proportion of the three HR in PLN and PSLN, whereas beta1 and beta7 integrins were proportionally more expressed than L-selectin in pharyngeal tonsil. beta7 integrin was proportionally more expressed than beta1 integrin or L-selectin in palatine tonsils, RLN and the mucosal mesenteric LN (MLN). beta1 integrin was proportionally more expressed in IgG+ and IgA+ cells than beta7 integrin and L-selectin in tonsils, PLN and RLN. The main endothelial addressin expressed on venules in both pharyngeal and palatine tonsils, the PLN and RLN, as well as in the PSLN, was the peripheral PNAd, while in the MLN it was MAdCAM-1. Conjunctival infection by Brucella resulted in an increase of CD4+CD25+ and CD4+CD45RA- T cell subsets, which was associated to modifications of HR expression. CD4+CD45RA- T cells expressed proportionally more beta1 and beta7 integrins than L-selectin in regional PLN and RLN, but also in PSLN. The infection induced an increase of IgG+ and IgA+ cell percentages expressing beta1 integrin in all LN, and also beta7 integrin in the RLN. PNAd continued to be expressed on venules of tonsils and draining LN after Brucella infection, and MAdCAM-1 was also weakly expressed on RLN venules. These results suggest that lymphocyte trafficking through tonsils and draining LN could involve L-selectin/PNAd interactions, as well as beta1 or beta7 integrin, possibly in interaction with VCAM-1 or MAdCAM-1. The homing of antigen-specific lymphocytes in these tissues could be modulated after conjunctival infection with Brucella, which induces the recruitment of lymphocytes that express both beta1 and/or beta7 integrin in regional and more distant LN. 相似文献
107.
Oremland RS Kulp TR Blum JS Hoeft SE Baesman S Miller LG Stolz JF 《Science (New York, N.Y.)》2005,308(5726):1305-1308
Searles Lake is a salt-saturated, alkaline brine unusually rich in the toxic element arsenic. Arsenic speciation changed from arsenate [As(V)] to arsenite [As(III)] with sediment depth. Incubated anoxic sediment slurries displayed dissimilatory As(V)-reductase activity that was markedly stimulated by H2 or sulfide, whereas aerobic slurries had rapid As(III)-oxidase activity. An anaerobic, extremely haloalkaliphilic bacterium was isolated from the sediment that grew via As(V) respiration, using either lactate or sulfide as its electron donor. Hence, a full biogeochemical cycle of arsenic occurs in Searles Lake, driven in part by inorganic electron donors. 相似文献
108.
109.
Sifre L Berge P Engel E Martin JF Bonny JM Listrat A Taylor R Culioli J 《Journal of agricultural and food chemistry》2005,53(21):8390-8399
The spatial distribution of the intramuscular connective tissue (IMCT) in four types of beef muscle (Biceps femoris, Infraspinatus, Longissimus thoracis, and Pectoralis profundus) was examined using histology and magnetic resonance imaging (MRI). The surface and the length of the IMCT and the surface of the myofiber bundles were evaluated by image analysis. The texture of the cooked meat from these muscles was measured both instrumentally by a compression test and by sensory analysis. The relationship between muscle structure and meat texture was studied by general discriminant analysis. The models obtained could assign correctly up to 87% of the samples to two tenderness classes. Histology and MRI provided complementary information about the microscopic and macroscopic IMCT structures, respectively. Both were necessary to predict sensory tenderness whereas only the MRI measurements were necessary to predict instrumental toughness. Tough muscles had smaller MRI myofiber bundles (0.7-1 mm radius) than tender muscles. 相似文献
110.
Praud A Gimenez O Zanella G Dufour B Pozzi N Antras V Meyer L Garin-Bastuji B 《Preventive veterinary medicine》2012,104(1-2):94-100
While serological tests are essential in surveillance and control programs of animal diseases, to date none of the common serological tests approved in the EU (complement fixation test or Rose-Bengal test) has been shown to be reliable in routine individual diagnosis of porcine brucellosis, and some more recent tests like ELISA have not been fully evaluated yet. In the absence of a gold standard, this study allowed the estimation of sensitivities and specificities of these tests with a Bayesian approach using Markov Chain Monte Carlo algorithms. The pig population that was tested included 6422 animals from Metropolitan France. Serum samples were collected from a large population of pigs, representative of European swine population and tested with five brucellosis serological tests: Rose-Bengal test (RBT), fluorescence polarization assay (FPA), indirect ELISA (I-ELISA) and two competitive ELISAs (C-ELISA). The sensitivity and the specificity of each test were estimated. When doubtful results were excluded, the most sensitive and specific test was C-ELISA(2) (Se C-ELISA(2)=0.964, [0.907; 0.994], 95% credibility interval (CrI); Sp C-ELISA(2)=0.996, [0.982; 1.0], 95% CrI). When doubtful results were considered as negative, C-ELISA(2) was still the most sensitive and specific test (Se C-ELISA(2)=0.960, [0.896; 0.994], 95% CrI and Sp C-ELISA(2)=0.994, [0.977; 0.999], 95% CrI). The same conclusions were reached when doubtful results were considered as positive (Se C-ELISA(2)=0.963, [0.904, 0.994], 95% CrI and Sp C-ELISA(2)=0.996, [0.986; 1.0], 95% CrI). 相似文献