全文获取类型
收费全文 | 799篇 |
免费 | 32篇 |
国内免费 | 2篇 |
专业分类
林业 | 57篇 |
农学 | 21篇 |
基础科学 | 3篇 |
141篇 | |
综合类 | 96篇 |
农作物 | 82篇 |
水产渔业 | 44篇 |
畜牧兽医 | 324篇 |
园艺 | 14篇 |
植物保护 | 51篇 |
出版年
2022年 | 8篇 |
2021年 | 16篇 |
2020年 | 21篇 |
2019年 | 14篇 |
2018年 | 17篇 |
2017年 | 8篇 |
2016年 | 10篇 |
2015年 | 18篇 |
2014年 | 24篇 |
2013年 | 36篇 |
2012年 | 32篇 |
2011年 | 48篇 |
2010年 | 24篇 |
2009年 | 24篇 |
2008年 | 44篇 |
2007年 | 44篇 |
2006年 | 28篇 |
2005年 | 42篇 |
2004年 | 34篇 |
2003年 | 41篇 |
2002年 | 32篇 |
2001年 | 11篇 |
2000年 | 11篇 |
1999年 | 18篇 |
1998年 | 6篇 |
1995年 | 12篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 9篇 |
1991年 | 12篇 |
1990年 | 10篇 |
1989年 | 11篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 14篇 |
1985年 | 6篇 |
1984年 | 9篇 |
1980年 | 4篇 |
1979年 | 8篇 |
1978年 | 5篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1971年 | 3篇 |
1969年 | 4篇 |
1966年 | 4篇 |
1962年 | 3篇 |
1961年 | 4篇 |
1960年 | 3篇 |
1955年 | 4篇 |
1913年 | 3篇 |
排序方式: 共有833条查询结果,搜索用时 218 毫秒
131.
132.
133.
Food safety is one of the major concerns in every country regardless of the economic and social development. The frequent occurrence of food scandals in the world has led the Chinese government to implement several strategies to fortify the food supply system to a high food safety standard. This relies heavily on laboratory testing services but conventional methods for detection of food contaminants and toxicants are limited by sophisticated sample preparation procedures,long analysis time,large instruments and professional personnel to meet the increasing demands. In this review,we have incorporated most of the current and potential rapid detection methods for many notorious food contaminants and toxicants including microbial agents,toxic ions,pesticides,veterinary drugs and preservatives,as well as detection of genetically modified food genes and adulterated edible oil. Development of rapid,accurate,easy-to-use and affordable testing methods could urge food handlers and the public to actively screen for food contaminants and toxicants instead of passively relying on monitoring by the government examination facility. This review also provides several recommendations including how to encourage the public to engage in the food safety management system and provide optimal education and financial assistance that may improve the current Chinese food safety control system. 相似文献
134.
In the years 2013 and 2014 the presence and the infestation level of Plasmodiophora brassicae in six federal states of Germany were assessed using a bioassay method. Soils were sampled from 237 oilseed rape fields and the farmers provided information about the soil type, the soil pH values and the last year of oilseed rape cultivation. Clubroot was detected in 66 % of the fields investigated with a mean disease severity (BI) of 0.34. Between and within the federal states differences in presence and infestation level of P. brassicae were detected. In Schleswig-Holstein significantly more fields were infected by P. brassicae (90 %) and BI was relatively high (0.49) compared to Lower Saxony, Mecklenburg-Western Pomerania and North Rhine-Westphalia with 50 % infected fields and a mean BI of 0.27. Highly infested fields (BI > 0.8) were prevalent on 15 and 25 % of fields investigated in every federal state. Within the federal states the soil climate regions (BKR) differed significantly from each other. In BKR with light and sandy soils P. brassicae was less widespread compared to neighboring BKR with loamy soils. In addition, BKR with high infestation levels on fields investigated revealed a high presence of clubroot infested fields within this BKR. The infestation level in our study was significantly influenced by soil type, content of sand and soil pH value: soil types with a sand content of 30–35 % and a pH values lower than 5.6 showed high clubroot severity and disease incidences. 相似文献
135.
This paper reports the results of tissue infectivity assays of bovine spongiform encephalopathy (BSE) agent in orally exposed cattle at stages during the incubation period. Estimations of the titre of infectivity in central nervous system (CNS), certain peripheral nerve ganglia and distal ileum tissue were made according to time post exposure from the relationship between incubation period and dose for RIII mice and C57bl mice using data from titrations of brain material from cases of BSE. The rate of increase of infectivity in the bovine CNS was then estimated, taking into account these tissue infectivity titres, the variability of the brain titre of clinical field cases of BSE, and the probability density of the expected number of months before clinical onset of each infected bovine. The doubling time for CNS was shown to equal 1.2 months. The titre in the thoracic dorsal root ganglia (DRG) was, on average, approximately 1 log units less than CNS, and cervical DRG approximately 0.5 log less than thoracic DRG. The pattern of increase of infectivity in the distal ileum is that of an initial increase up to 14-18 months post exposure, followed by a decrease, which is likely to be highly variable between animals. These results will be informative for future risk assessments of BSE, especially in relation to reviewing current control measures. 相似文献
136.
Mohammadali Khalvati Bernadett Bartha Arthur Dupigny Peter Schröder 《Journal of Soils and Sediments》2010,10(1):54-64
Background, aim, and scope
Plant growth and productivity under abiotic stresses such as water shortage or pollution are major problems which currently worry scientists in the field of food production and plant health. Since the intensification of livestock production with its associated increased demand for fodder has encouraged farmers to rely more heavily on chemical fertilizers, very often, municipal waste and wastewater sludge is considered a possible source of plant nutrients, although it might carry a significant amount of anthropogeneous pollutants. The extent to which plants react to drought, as well as how pollutants are taken up or how they act on plants, might depend on rhizosphere processes such as mycorrhizal symbioses. Therefore, it seemed timely to investigate plant defense reactions in the presence of arbuscular mycorrhizal fungi (AMF) toward a possible dangerous sewage sludge pollutant under the influence of drought. 相似文献137.
Nednaldo Dantas-Santos Jailma Almeida-Lima Arthur Anthunes Jacome Vidal Dayanne Lopes Gomes Ruth Medeiros Oliveira Silvia Santos Pedrosa Paula Pereira Francisco Miguel Gama Hugo Alexandre Oliveira Rocha 《Marine drugs》2012,10(9):2002-2022
Sulfated fucans comprise families of polydisperse natural polysaccharides based on sulfated L-fucose. Our aim was to investigate whether fucan nanogel induces cell-specific responses. To that end, a non toxic fucan extracted from Spatoglossum schröederi was chemically modified by grafting hexadecylamine to the polymer hydrophilic backbone. The resulting modified material (SNFuc) formed nanosized particles. The degree of substitution with hydrophobic chains was close to 100%, as estimated by elemental analysis. SNFfuc in aqueous media had a mean diameter of 123 nm and zeta potential of −38.3 ± 0.74 mV, as measured by dynamic light scattering. Nanoparticles conserved their size for up to 70 days. SNFuc cytotoxicity was determined using the MTT assay after culturing different cell lines for 24 h. Tumor-cell (HepG2, 786, H-S5) proliferation was inhibited by 2.0%–43.7% at nanogel concentrations of 0.05–0.5 mg/mL and rabbit aorta endothelial cells (RAEC) non-tumor cell line proliferation displayed inhibition of 8.0%–22.0%. On the other hand, nanogel improved Chinese hamster ovary (CHO) and monocyte macrophage cell (RAW) non-tumor cell line proliferation in the same concentration range. The antiproliferative effect against tumor cells was also confirmed using the BrdU test. Flow cytometric analysis revealed that the fucan nanogel inhibited 786 cell proliferation through caspase and caspase-independent mechanisms. In addition, SNFuc blocks 786 cell passages in the S and G2-M phases of the cell cycle. 相似文献
138.
Romildo Rocha Azevedo Junior Janaina Biral dos Santos Dilmar Baretta Alessandro Coutinho Ramos Arthur Prudêncio de Araujo Pereira Elke Jurandy Bran Nogueira Cardoso 《Journal of plant nutrition》2017,40(14):2076-2086
The goal of this study was to evaluate the effect of organic (OS) and conventional (CS) farming of Arabica coffee on chemical and microbiological soil properties and to identify which attributes correlate and/or contribute to distinguishing these two management systems. We collected soil samples on a 100 × 100 m2 grid in both, the OS and CS, in winter and summer and submitted chemical and microbiological properties to univariate and multivariate analyses (canonical discriminant analysis – CDA – and redundancy analysis – RDA). The best indicators to discriminate OS and CS were chemical and microbiological properties, as the elements calcium (Ca) and boron (B), besides microbial biomass carbon (MBC), metabolic quotient (qCO2), acid phosphatase (ACP), and alkaline phosphatase (ALP). The RDA showed that, regardless of the season, MBC and ACP correlated with nitrogen (N), sulfur (S) and organic matter (OM), whereas basal respiration (C-CO2) and ACP correlated with qCO2 and with magnesium (Mg), calcium (Ca), phosphorus (P), potassium (K) and pH. 相似文献
139.
Larissa Sarmento dos Santos Joicy Cortez Sá Diego Luiz dos Santos Ribeiro Nancyleni Pinto Chaves Juliana Pinto da Silva Mol Renato Lima Santos Tatiane Alves da Paixão Alcina Vieira de Carvalho Neta 《Tropical animal health and production》2017,49(4):675-679
The aim of the current study is to diagnose Brucella spp. infection using methods such as serology, bacterial isolation, and molecular analysis in buffaloes bred in Maranhão State. In order to do so, 390 samples of buffalo serum were subjected to serological tests, to Rose Bengal Plate Test (RBPT) and to 2-mercaptoethanol (2-ME) combined with slow agglutination test (SAT). Vaginal swabs were collected from seropositive animals and subjected to bacterial isolation and to generic PCR. According to the serological test, 16 animals had a positive reaction to the confirmatory test (2-ME/SAT). As for bacterial isolation, three samples resulted in the isolation of Brucella spp.-characteristic colonies, which were confirmed through PCR. These results confirmed Brucella spp. infection in the buffalo herd from Maranhão State. 相似文献
140.
Disposition of the anti‐ulcer medications ranitidine,cimetidine, and omeprazole following administration of multiple doses to exercised Thoroughbred horses
下载免费PDF全文
![点击此处可从《Journal of veterinary pharmacology and therapeutics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
H. K. Knych S. D. Stanley R. M. Arthur D. S. McKemie 《Journal of veterinary pharmacology and therapeutics》2017,40(1):92-96
The use of anti‐ulcer medications, such as cimetidine, ranitidine, and omeprazole, is common in performance horses. The use of these drugs is regulated in performance horses, and as such a withdrawal time is necessary prior to competition to avoid a medication violation. To the authors' knowledge, there are no reports in the literature describing repeated oral administrations of these drugs in the horse to determine a regulatory threshold and related withdrawal time recommendations. Therefore, the objective of the current study was to describe the disposition and elimination pharmacokinetics of these anti‐ulcer medications following oral administration to provide data upon which appropriate regulatory recommendations can be established. Nine exercised Thoroughbred horses were administered 20 mg/kg BID of cimetidine or 8 mg/kg BID of ranitidine, both for seven doses or 2.28 g of omeprazole SID for four doses. Blood samples were collected, serum drug concentrations were determined, and elimination pharmacokinetic parameters were calculated. The serum elimination half‐life was 7.05 ± 1.02, 7.43 ± 0.851 and 3.94 ± 1.04 h for cimetidine, ranitidine, and omeprazole, respectively. Serum cimetidine and ranitidine concentrations were above the LOQ and omeprazole and omeprazole sulfide below the LOQ in all horses studied upon termination of sample collection. 相似文献