全文获取类型
收费全文 | 622篇 |
免费 | 54篇 |
国内免费 | 3篇 |
专业分类
林业 | 26篇 |
农学 | 19篇 |
基础科学 | 3篇 |
142篇 | |
综合类 | 48篇 |
农作物 | 27篇 |
水产渔业 | 45篇 |
畜牧兽医 | 309篇 |
园艺 | 21篇 |
植物保护 | 39篇 |
出版年
2023年 | 4篇 |
2022年 | 8篇 |
2021年 | 24篇 |
2020年 | 28篇 |
2019年 | 32篇 |
2018年 | 20篇 |
2017年 | 17篇 |
2016年 | 22篇 |
2015年 | 17篇 |
2014年 | 24篇 |
2013年 | 31篇 |
2012年 | 54篇 |
2011年 | 60篇 |
2010年 | 24篇 |
2009年 | 26篇 |
2008年 | 36篇 |
2007年 | 37篇 |
2006年 | 31篇 |
2005年 | 28篇 |
2004年 | 21篇 |
2003年 | 19篇 |
2002年 | 20篇 |
2001年 | 11篇 |
2000年 | 5篇 |
1999年 | 7篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 3篇 |
1966年 | 3篇 |
1965年 | 1篇 |
1961年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有679条查询结果,搜索用时 15 毫秒
31.
Almy Junior Cordeiro de Carvalho Patrícia Soares Furno Fontes Marta Simone Mendonça Freitas Pedro Henrique Monnerat Alexandre Gomes Fontes 《Journal of plant nutrition》2013,36(4):614-626
This work was performed in the Rio de Janeiro State, Brazil, with the objective to evaluate the nutritional status of yellow passion fruit plants along different phenological stages, using the DRIS method. Fifty-four passion fruit cultivated areas with an annual yield productivity ranging from 6.95 to 33.8 t ha?1 year?1 and average productivity of 16.9 t ha?1 year?1 were selected in the region. The contents of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), chlorine (Cl), iron (Fe), zinc (Zn), manganese (Mn), and boron (B) were evaluated. The reference standards were established (mean and variation coefficient) for the values of the nutrient concentration ratios, two by two, on samples from high yield productivity plantations and analyzed by the DRIS index of nutrients for the medium and low yield productivity areas. The established standards differed according with the phenological stage of the culture. In a general way, the mean content of the evaluated nutrients did not differed between the two productivity levels into each phonological stage. There was a difference for the Nutritional Limitation Order between different phenological stages of yellow passion fruit plants. The most negative DRIS indexes and the highest absolute values for the Average Nutritional Balance on yellow passion fruit plants in the region, were found for potassium in May, phosphorus in October and iron in January. 相似文献
32.
Simone TelesJosé Alberto Pereira Carlos H.B. SantosRenata V. Menezes Ricardo MalheiroAngélica M. Lucchese Franceli Silva 《Industrial Crops and Products》2012,37(1):247-252
Lippia alba (Mill.) N.E. Brown, the ginger grass, is a medicinal and aromatic plant widely used in Latin America. In this work the effect of the geographical origin and different drying methodologies on L. alba leaves production, essential oil content and composition were evaluated. Field experiments were conducted in three different municipalities (Amargosa, Cruz das Almas and Santo Antônio de Jesus) from Bahia region (Brazil) and two drying methodologies (traditional and artificial with controlled conditions) were assessed. Fresh and dried leaves essential oils were extracted by hydro-distillation and their volatiles were determined by gas chromatography.The geographical origin affected the mass production, essential oil content and both qualitative and quantitative fractions of their composition. Leaves from Cruz das Almas had higher yield in essential oil content. Overall, 26 oil constituents were identified. Carvone, germacrene D and limonene were the main oil constituents. The drying methodologies combined with the geographic origin influenced essential oil composition showing that L. alba constituents were influenced by post-harvest treatments. Some constituents were sensitive to both methods applied, while some enhanced their content like germacrene D. 相似文献
33.
Cavaletto Giacomo Faccoli Massimo Marini Lorenzo Spaethe Johannes Giannone Filippo Moino Simone Rassati Davide 《Journal of pest science》2021,94(3):871-883
Journal of Pest Science - Longhorn beetles are commonly moved among continents within wood packaging materials used in trades. Visual inspections carried out at points of entry often fail to detect... 相似文献
34.
The aim of this paper was to give a basic understanding of studies on methane emissions of New Zealand, as we know the agriculture of New Zealand is pastoral farming, most livestock animals are grazed in pasture, and quantities of methane were released from the digestive tract and animals excreta. In New Zealand some 50% greenhouse gases (GHG) sources are attributed to agriculture and one third is methane from livestock enteric formation. For many years, many researchers have been exploiting the techniques and methods to measure the emission of methane of New Zealand, further more studing the available options to alleviate the methane emissions. Their pioneering work and successful experiences including the determined methods and mitigation strategies are worth learning for scholars around the world. Some of their approaches were not only suitable for New Zealand grazed livestock, but for many other countries, even the animals are intensively bred in pen. The calorimeter/respiration chamber is the most exactly method in present, but it needs expensive equipments and skilled manipulators, so there are still some difficulty in applying this approach extensively in practice. Sulfur hexafluoride (SF6) trace technique is much adopted for grazed livestock evaluating the methane emission, though its veracity was doubted by some researchers, it is still a good option in present for studying the GHG emissions for grazing animals. By measuring the rumen volatile fatty acid (VFA) concentration to estimate the methane emission is a relatively simple approach, it is just only a rough evaluation, and it is unsuitable for exact study, but this method may be used in China for extensively raised ruminant. In present China, the ruminants are fed in an extensively managed state, the diversities of roughage and animals varieties caused difficult to exactly estimate the methane emission. So exploiting the available options is much important for constituting the exhaustive emission inventory. This review just maybe a good reference for researchers to carry out their studies in years and acquired great achievements in methane mitigation area. outline some practical techniques of New Zealand, those this field, after all New Zealand have been persisting many 相似文献
35.
Daniele Grifoni Marco Napoli Francesco Sabatini Simone Orlandini Marco Mancini Gaetano Zipoli Anna Dalla Marta 《Journal of Agronomy and Crop Science》2019,205(4):422-432
A UV exclusion experiment was conducted on durum wheat (Triticum durum Desf. var. Claudio) grown in pots. Plants were grown under three different radiative treatments in greenhouses covered with plastic filters: Teflon, transparent to the entire region of natural UV‐visible sunlight (TEF); polyester, transparent above 312 nm (MYL, excluding UVB) and Lee, transparent above 400 nm (LEE, excluding both UVA and UVB). Analyses have been carried out to determine the concentration of photosynthetic pigments in leaves, UV‐absorbing compounds, nitrogen and carbon in leaves, culms and spikes and proteins and gluten in grains. In particular, plants grown under UV exclusion showed a reduction in protein and dry gluten content (consequently without variation in the ratio dry gluten/protein), but at the same time, a significant increase of gluten index, which is a parameter to define the quality of gluten, was observed. The results highlighted the influence played by UV radiation on some biochemical parameters, mainly UV‐absorbing compounds, leaf nitrogen and grain protein characteristics of durum wheat cultivated under Mediterranean conditions. In particular, natural level of UV in the Mediterranean improves the characteristics of durum wheat flour important for pasta production (high dry gluten level), while the UV exclusion could improve characteristics of flour important for bread production (high gluten index). 相似文献
36.
37.
Samanta A Costa MH Nunes EL Vieira SA Xu L Myneni RB 《Science (New York, N.Y.)》2011,333(6046):1093; author reply 1093
Zhao and Running (Reports, 20 August 2010, p. 940) reported a reduction in global terrestrial net primary production (NPP) from 2000 through 2009. We argue that the small trends, regional patterns, and interannual variations that they describe are artifacts of their NPP model. Satellite observations of vegetation activity show no statistically significant changes in more than 85% of the vegetated lands south of 70°N during the same 2000 to 2009 period. 相似文献
38.
Fulvio Bordin Chiara Dalvit Mauro Caldon Laura Zulian Rosa Colamonico Simone Trincanato Barbara Mock Stefano Reale Franco Mutinelli Anna Granato 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2020,137(4):395-406
Scrapie is an ovine transmissible spongiform encephalopathy, and its susceptibility is associated with polymorphisms in the prion protein gene (PRNP). Genetic selection is currently the most effective mean for eradication of the susceptible VRQ allele in favour of resistant ARR allele. Maintenance of genetic diversity should be one of the major objectives in breeding programmes, especially in endangered breeds, and genetic information are an excellent alternative to pedigree data where these information are missing. The aim of our study was to determine changes of genetic variability in six native sheep breeds from autonomous province of Bolzano, northern Italy, following simulation of scrapie selection scenarios. A total of 684 rams were investigated for PRNP polymorphisms and for 10 microsatellite loci to estimate genetic variability. Across all loci, a total of 163 alleles were detected with a mean of 10.4 alleles per locus. Average observed (Ho) and unbiased expected (uHe) heterozygosity overall loci were 0.74 and 0.78, respectively, showing a statistically significant deviation from Hardy–Weinberg equilibrium (HWE) in all breeds. This heterozygosity deficit was confirmed by a positive fixation index (Fis), determining a moderate inbreeding in each breed. Simulating a soft selection, where only rams having at least a VRQ allele should be excluded from reproduction, Ho, uHe and Fis values remained almost unchanged, indicating that genetic variability should not be affected by the removal of these individuals. With a mild selection scenario, considering only rams with at least one ARR allele, we observed a decrease in the mean alleles per breed (8.9) and the maintenance of heterozygosity deficiency, except for two breeds, where it was any longer significant. These results showed that selection strategies allowing use of heterozygous as well homozygous ARR rams might be the right compromise to improve resistance to scrapie and to do not dramatically affect genetic variability of these breeds. 相似文献
39.
Camargo MG Golo PS Angelo IC Perinotto WM Sá FA Quinelato S Bittencourt VR 《Veterinary parasitology》2012,188(1-2):140-147
The formulations of acaripathogenic fungi to control ticks have been widely studied. The present study evaluated the efficacy of oil-based formulations of Metarhizium anisopliae sensu lato (s.l.), isolate Ma 959, and Beauveria bassiana, isolate Bb 986, on different Rhipicephalus microplus stages, comparing the efficacy between aqueous suspensions and 10, 15 and 20% mineral oil formulations. Twelve groups were formed: one aqueous control group; three mineral oil control groups, at 10, 15 or 20%; two aqueous fungal suspensions of M. anisopliae s.l. or B. bassiana; and three formulations of M. anisopliae (s.l.) or B. bassiana containing 10, 15, and 20% mineral oil. To prepare aqueous suspensions and oily formulations, fungal isolates were cultivated on rice grains in polypropylene bags. The conidial suspensions and formulations had a concentration of 10(8)conidia/mL. Bioassays were repeated twice. After treatment, the following biological parameters of engorged females were evaluated: hatching percentage, egg production index, nutritional index, and percentage of tick control. The following parameters were evaluated in the bioassays with eggs: period of incubation, period of hatch, and hatching percentage. Mortality was evaluated in bioassays with larvae. M. anisopliae s.l. and B. bassiana oil-based formulations were more effective than aqueous suspensions against R. microplus eggs, larvae and engorged females, however, there was no significant difference between the three oil concentrations used. M. anisopliae s.l. and B. bassiana formulated in mineral oil reached 93.69% and 21.67% efficacy, respectively, while M. anisopliae s.l. and B. bassiana aqueous suspensions attained 18.70% and 1.72% efficacy, respectively. M. anisopliae s.l. oil-based formulations caused significant effects in all biological parameters of engorged females while B. bassiana oil-based formulations modified significantly the nutritional index only. Eggs treated with M. anisopliae s.l. and B. bassiana oil-based formulations showed hatching rates that decreased 102.5 and 3.65 times, respectively. In the bioassay with larvae, M. anisopliae s.l. oil-based formulations caused nearly 100% mortality five days after treatment, while larva treated with B. bassiana oil-based formulations reached 100% mortality at day 20 after treatment. Larva from oil-based control groups showed mortality at day 15 after treatment, which indicated a possible toxic effect of the oil for this R. microplus stage. The results showed that the fungal mineral oil formulations tested were more effective than the aqueous suspension. Oil-based formulations at 10, 15 and 20% enhanced the activity of M. anisopliae s.l. Ma 959, and B. bassiana Bb 986, isolates against R. microplus eggs, larvae, and engorged females tick. Mineral oil was effective as an adjuvant in formulations of M. anisopliae s.l., Ma 959, and B. bassiana, Bb 986, for the control of R. microplus under laboratory conditions. 相似文献
40.
Daniella M. Silva Aline I. Franciosi Paula C.F. Pezzini Simone D. Guérios 《The Canadian veterinary journal. La revue veterinaire canadienne》2015,56(8):823-830
Intravenous paclitaxel has been underused in dogs due to severe and acute hypersensitivity reactions. Subcutaneous (SC) administration of paclitaxel and its safety are unknown. In this preliminary study, SC administration of paclitaxel was evaluated for hypersensitivity reactions and toxicity in 21 dogs with advanced cancer. Dogs received 1 to 5 paclitaxel doses, ranging from 85 to 170 mg/m2, SC every 14 or 21 days. A total of 40 paclitaxel doses were administered and none of the 21 dogs developed systemic or acute local hypersensitivity reactions. Severe skin lesions at the injection site developed in 2 dogs after the 4th injection at the same location. Grade 4 neutropenia was observed in 50% of the dogs 5 days after the first treatment at 115 mg/m2 (n = 14). Two animals developed Grade 5 diarrhea and died likely due to hemodynamic failure or sepsis. Paclitaxel can be administered SC in dogs with no hypersensitivity reaction. 相似文献