全文获取类型
收费全文 | 2306篇 |
免费 | 146篇 |
专业分类
林业 | 177篇 |
农学 | 116篇 |
基础科学 | 12篇 |
514篇 | |
综合类 | 126篇 |
农作物 | 124篇 |
水产渔业 | 348篇 |
畜牧兽医 | 847篇 |
园艺 | 53篇 |
植物保护 | 135篇 |
出版年
2024年 | 2篇 |
2023年 | 33篇 |
2022年 | 51篇 |
2021年 | 106篇 |
2020年 | 85篇 |
2019年 | 116篇 |
2018年 | 89篇 |
2017年 | 95篇 |
2016年 | 84篇 |
2015年 | 64篇 |
2014年 | 101篇 |
2013年 | 130篇 |
2012年 | 179篇 |
2011年 | 196篇 |
2010年 | 110篇 |
2009年 | 117篇 |
2008年 | 126篇 |
2007年 | 125篇 |
2006年 | 110篇 |
2005年 | 100篇 |
2004年 | 98篇 |
2003年 | 93篇 |
2002年 | 66篇 |
2001年 | 17篇 |
2000年 | 16篇 |
1999年 | 19篇 |
1998年 | 18篇 |
1997年 | 10篇 |
1996年 | 5篇 |
1995年 | 11篇 |
1994年 | 7篇 |
1993年 | 7篇 |
1992年 | 8篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1978年 | 4篇 |
1976年 | 3篇 |
1971年 | 3篇 |
1968年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有2452条查询结果,搜索用时 19 毫秒
901.
Valerie Chetboul Amandine Petit Vassiliki Gouni Emilie Trehiou-Sechi Charlotte Misbach David Balouka Carolina Carlos Sampedrano Jean-Louis Pouchelon Renaud Tissier Marie Abitbol 《Journal of Veterinary Cardiology》2012,14(4):497-509
Objectives(1) To investigate heart morphology and function using echocardiography and tissue Doppler imaging (TDI), (2) to determine heart disease prevalence and characteristics, and (3) to assess potential genetic features in a population of Sphynx cats presented for cardiovascular screening.AnimalsA total of 147 echocardiographic examinations, including 33 follow-ups, were performed by trained observers on 114 Sphynx cats of different ages (2.62 ± 1.93 years [0.5–10.0]) from 2004 to 2011.MethodsSphynx cats underwent a physical examination, conventional echocardiography, and, if possible, two-dimensional color TDI.ResultsConventional echocardiographic findings included 75/114 normal (65.8%) and 39/114 (34.2%) abnormal examinations with a diagnosis of either congenital heart diseases (n = 16) or hypertrophic cardiomyopathy (HCM, n = 23). In adult healthy cats, a significant body weight effect was observed for several echocardiographic variables, including end-diastolic left ventricular (LV) free wall (P < 0.01), interventricular septum (P < 0.001), and LV diameter (P < 0.001). Mitral valve dysplasia (MVD) was observed as a single or associated defect in 15/16 cats with congenital heart diseases. A significant increase in HCM prevalence (P < 0.001) was observed according to age. The pedigree analysis of a large family (n = 81) suggested an autosomal dominant mode of inheritance with incomplete penetrance for HCM.ConclusionsBody weight should be taken into account when interpreting values of diastolic myocardial wall thicknesses in Sphynx cats. Additionally, HCM and MVD are two relatively common heart diseases in this feline breed. More pedigree data are required to confirm the inheritance pattern of HCM at the breed level. 相似文献
902.
García-Hernández Y Rodríguez Z Brandão LR Rosa CA Nicoli JR Elías Iglesias A Peréz-Sanchez T Salabarría RB Halaihel N 《Research in veterinary science》2012,93(2):798-802
The objective of this study was to isolate and identify yeast strains from broilers excreta and to evaluate in vitro their potential for probiotic use in animal production.Methods and resultsNine yeast strains were isolated and presumptively pre-identified by biochemical assays. These isolates were grouped in six different molecular profiles using PCR-fingerprinting technique. Each profile was identified by sequencing of the D1/D2 domains of the large subunit of the 26S rRNA gene. These yeasts were identified as: Trichosporon sp. (LV-2), Wickerhamomyces anomalus (LV-6), Pichia kudriavzevii (LV-8), Kodamaea ohmeri (LV-9) and Trichosporon asahii (LV-10). A pre-screening of the strains for probiotic use was based on their ability to agglutinate pathogenic micro-organisms. These yeast strains were characterized for specific growth rate, duplication time, their cell surface hydrophobicity, medium acidification, resistance to low pH (2.0, 2.5 and 3.0) and concentrations of bile salts (0.3% and 0.6%). The isolate of W. anomalus (LV-6) had the highest agglutinating and adherence capacity, a growth rate of 2.07 × 108 cfu/mL in 24 h at 30 °C, decreasing the medium pH from 6.5 to 5.23, a 25% hydrophobicity and an elevated capacity to grow under stress conditions.ConclusionsW. anomalus strain LV-6 showed the best characteristics for use as a probiotic candidate.Significance and impact of the Study:The data from this study helped in choosing a probiotic candidate from yeast to use in broiler production. 相似文献
903.
Miranda-de la Lama GC Villarroel M Campo Mdel M Olleta JL Sañudo C María GA 《Tropical animal health and production》2012,44(1):21-27
The objective of the current study was to analyse the effects of double transport and season on sensorial aspects of lamb's
meat quality in dry climates. A total of 144 lambs were sampled in a 3 × 2 × 2 factorial design, testing three types of double
transport along the residence time at a pre-slaughter classification centre or CC (0, 7 and 28 days) and two seasons (summer
and winter), with two replicates in each season. Meat from the M. longissimus was analysed in terms of pH and WHC and tasted by a trained sensory panel in terms of lamb odour intensity, tenderness, juiciness,
lamb flavour intensity, fat flavour intensity, liver flavour intensity, metallic flavour intensity and overall liking. Meat
sensorial quality traits were not significantly affected by double transport. Season had a significant (P < 0.001) effect on all variables analysed, except for lamb flavour intensity and overall liking. Interactions between the
fixed effects were not significant, with the exception of tenderness. Season significantly affects several sensorial variables,
and they seem to be independent of double transport, with the exception of tenderness. 相似文献
904.
Flores-Mendoza L Velazquez C Bray J Njongmeta L Mwangi W Hernández J 《Veterinary immunology and immunopathology》2012,146(1):74-80
The aim of this work was to develop mAbs against porcine CD205 and to conduct a comparative analysis of the CD205 protein expression on lymphoid tissues, monocyte-derived dendritic cells (DCs) and DCs isolated from the porcine skin. To conduct this study, we generated a monoclonal antibody, designated 1.F6F6, against the C-type lectin-like domain-5 of the porcine CD205 and showed that it recognizes a protein band of ~200 kDa by Western Blot analysis in mesenteric lymph nodes cells. Flow cytometric analysis showed that the mAb 1.F6F6 recognized 28.5%, 28.1% and 34.1% of cells from tonsil, inguinal and mesenteric lymph nodes, respectively, and 6% of cells from thymus. Analysis of monocyte-derived DCs showed that approximately 20% were positive and activation of the cells with LPS increased the positive population to 36%. Analysis of DCs isolated from the porcine skin showed that approximately 70% of the cell population expressed the CD205 receptor. The development of a monoclonal antibody capable of recognizing the CD205 receptor in swine opens up possibilities of applying new strategies for enhancing vaccine efficacy by using the anti-CD205 antibody for DC antigen-targeting to enhance priming of immune responses. 相似文献
905.
Marcos Barros-Rodríguez Javier Solorio-Sánchez Juan Ku-Vera Armín Ayala-Burgos Carlos Sandoval-Castro Georgina Solís-Pérez 《Tropical animal health and production》2012,44(8):1873-1878
The aim of this study was to evaluate daily weight gain (DWG), total dry matter (DM) intake, rumen degradability of forage, and urinary excretion of mimosine metabolites by hair sheep in a silvopastoral system with high densities of Leucaena leucocephala. A completely randomized design was carried out with two treatments: treatment 1 (T1) silvopastoral system with leucaena at a density of 35,000 plants/ha and treatment 2 (T2), leucaena at a density of 55,000 plants/ha. Leucaena was associated with tropical grasses Panicum maximum and Cynodon nlemfluensis. Twenty-four male Pelibuey lambs of 23.2?±?3.4?kg live weight (LW) were used (12 lambs per treatment). Results showed differences (P?<?0.05) in DWG of T1 (106.41?±?11.66?g?1 sheep?1) with respect to that of T2 (81.33?±?11.81?g?1 sheep). Voluntary intake was higher in lambs from T1 (83.81?±?04.07?g DM/kg LW0.75) with respect to that from T2 (71.67?±?8.12?g DM/kg LW0.75). There was a difference in color of urine between sheep of T1 and T2, the latter giving positive results for the presence of metabolites derived from mimosine (3-4 dihydroxypyridine and 2-3 dihydroxy pyridone). Rumen degradability of DM of L. leucocephala was higher (P?<?0.05) compared to that of P. maximum and C. nlemfluensis (72.94?±?0.40 vs. 67.06?±?1.50 and 63.25?±?1.51?%, respectively). It is concluded that grazing at high densities of L. leucocephala affects daily weight gain of hair sheep, possibly due to ingestion of high amounts of mimosine which may exert an adverse effect on voluntary intake. 相似文献
906.
Seixas A Oliveira P Termignoni C Logullo C Masuda A da Silva Vaz I 《Veterinary immunology and immunopathology》2012,148(1-2):149-156
Rhipicephalus (Boophilus) microplus is one of the most widely distributed tick in the world. The control of the parasite is based mainly on the use of chemical acaricides, which are produced from a limited set of molecules. These drugs induce selection of acaricide-resistant ticks, and are an important source of environmental pollution. An approach based on anti-tick vaccines may circumvent these obstacles. Characterization of the physiological function of tick molecules may be useful to develop new vaccines. Previously, we reported the ability of some tick proteins as inducers of protective immune response. Vaccination studies using tick proteins like native (nBYC), recombinant (rBYC) egg-yolk aspartic endopeptidase and cysteine endopeptidase (VTDCE) from R. microplus and glutathione S-transferase (Hl-GST) from Haemaphysalis longicornis demonstrated the immunogenicity and antigenicity of these proteins in bovines. Eventually, immunization with these proteins triggered a partial immune response against R. microplus infestation in cattle, manifested mainly as a reduction in egg fertility (7.7% and 13.9% for nBYC, 5.9% for rBYC; 4.7% for VTDCE, 7.9% for Hl-GST), and in the number of fully engorged ticks (18.2% for rBYC, 14.6% for VTDCE, 53% for Hl-GST). The data so far obtained suggest that these proteins have potential to be used as antigens in an anti-tick vaccine. Other proteins involved in tick embryogenesis also have this potential, like THAP and BmCl1, which are enzymes with key roles in vitellin and hemoglobin hydrolysis. Moreover, the identification of analogous proteins present in other tick species may bring information about the way to develop a vaccine against multiple tick species which can help to solve the problem faced by numerous countries where animals are parasitized by more than one tick species. The aim of the present review is to comprehensibly summarize the data obtained in the last few years by our collaborative research, discussing the efforts we have made to find antigens efficient enough for a cattle tick-controlling vaccine. This review discusses tick physiology studies aimed at the selection of possible targets, characterization of the selected proteins with emphasis on their biochemical and immunological aspects and results of vaccine trials on bovines. 相似文献
907.
Marja H. Bakermans Amanda D. Rodewald Andrew C. Vitz Carlos Rengifo 《Agroforestry Systems》2012,85(1):85-94
Shade coffee plantations support high numbers of Neotropical migratory birds, but relatively little is known about the structural and floristic attributes used by individual species. From 2005 to 2007, we studied the relationship between habitat characteristics and Neotropical migratory birds in shade coffee plantations in the Venezuelan Andes. Our results indicate that density of migrants was significantly related to both structural and floristic attributes of coffee farms. Specifically, upper canopy foragers were positively associated with number of large trees (>38?cm dbh), tree canopy height, and understory vegetation density. Low canopy and ground foragers were positively associated with numbers of small (8?C23?cm dbh) and medium (23?C38?cm dbh) trees and increased shade cover. Moreover, certain tree species, especially Inga spp., Erythrina spp. and Acnistus arborescens, were important components of habitat for those species that forage in the canopy. For example, our detailed foraging observations showed that Inga trees were used in greater proportion than available throughout plantations by Cerulean Warblers (Dendroica cerulea), a species of high conservation concern. Overall, our research suggests that suitability of coffee plantations for migratory birds may be improved by managing for particular structural and floristic characteristics of plantations. 相似文献
908.
Virginia Hernández-Santana José Martínez-Fernández Carlos Morán Ana Cano 《European Journal of Forest Research》2008,127(5):369-378
In the present study, carried out from 2004 to 2006, leaf and stem water potential and stem water content were measured in
Quercus pyrenaica Willd. individuals in an experimental forested catchment located in Central Western Spain under Mediterranean subhumid conditions.
These indicators of tree water status were compared with soil moisture contents measured in the same area from 0 to 1 m depth
and from 0 to 2.5 m depth during the last year of the study. The objectives were to clarify the seasonal and year-to-year
variations in tree water status, to examine applicability of stem water content as useful water stress indicator and to discuss
how deep soil water and root uptake contribute to survival during the long dry summer. Seasonal variations in the tree variables
measured revealed a typical pattern, with maximum values at the end of spring followed by a progressive decline during the
summer drought in response to the decrease in soil water content (almost exhausted at 0–100 cm depth). The relatively high
values and the non-significant variation in predawn leaf water potentials (except for 2005, which was exceptionally dry) indicate
that no clear water stress situations occurred. This may be explained in terms of a progressive absorption of water from the
deeper layers. The results also suggest that the stem water content is a more sensitive indicator of long-term water limitation
than the other variables measured. 相似文献
909.
The International Maize and Wheat Improvement Center (CIMMYT) is the global leader in publicly-funded maize and wheat research and in farming systems based on these crops. CIMMYT leads the Global Wheat Program (GWP), which includes some of the largest wheat breeding programs in the world. The GWP has been successful in developing wheat germplasm that is used extensively worldwide. Wheat quality improvement is a central component of all the breeding efforts at CIMMYT and the Wheat Chemistry and Quality Laboratory represents an integral part of the breeding programs. Wheat quality is addressed at CIMMYT over the full range of this very wide and variable concept with milling, processing, end-use and nutritional quality targeted. Wheat progenitors and advanced lines developed by the breeders are assessed for diverse quality attributes, with the aim of identifying those that fulfill the requirements in terms of milling, processing, end-use and nutritional quality in different target regions. Significant research is conducted to make more efficient the integration of wheat quality traits in the breeding programs. The main topics being addressed are (1) methodologies to analyze grain quality traits, (2) genetic control and environmental effects on quality traits, (3) characterization of genetic resources for quality improvement, and (4) diversifying grain properties for novel uses. 相似文献
910.
Paulo Cesar Pazdiora Keilor da Rosa Dorneles Carlos Alberto Forcelini Emerson Medeiros Del Ponte Leandro José Dallagnol 《European journal of plant pathology / European Foundation for Plant Pathology》2018,150(1):49-56
Tan spot caused by Pyrenophora tritici-repentis is the main foliar diseases of wheat in Brazil. The effect of silicon (Si) on the components of resistance of a susceptible (Fundacep Horizonte) and a moderately resistant (Quartzo) wheat cultivar was studied in a controlled environment. Silicon was supplied as calcium silicate in the soil 30 days before sowing. At the booting stage, a conidial suspension of the fungus was sprayed onto the flag leaves of potted plants, which were incubated under moist conditions for 48 h. Afterwards, inoculated leaves were assessed for: incubation period (IP), infection efficiency (IE), area under lesion size curve (AULSC), lesion size (LS), severity (SEV) and area under severity curve (AUSC). Foliar Si concentrations were quantified at the end of the evaluations. Si supply to plants increased leaf Si concentration in 233% for Fundacep Horizonte (from 4.8 to 16.0 g kg?1 of dry matter) and 211% for Quartzo (from 5.3 to 16.5 g kg?1 of dry matter). In the Si + treatments, IP was longer by 24 and 17 h, IE declined by 53.5 and 65.5%, LS (at 264 h after inoculation) by 4.6 mm (from 9.5 to 4.9 mm) and 5.9 mm (from 8.2 to 2.3 mm), and SEV by 53% (from 54.4 to 18.8%) and 88% (from 47.7 to 5.5%) respectively, for the Fundacep Horizonte and Quartzo cultivars. The Si x cultivar interaction was not significant for AULSC and AUSC, and these variables were reduced by 55.8 and 80.8%, respectively, in plants supplied with Si. In conclusion, Si enhanced the resistance of wheat plants to tan spot development by affecting several resistance components, regardless of the resistance level of the cultivar. However, the greatest reduction in tan spot development by Si supply was observed when using a moderately resistant cultivar. 相似文献