全文获取类型
收费全文 | 557篇 |
免费 | 63篇 |
国内免费 | 1篇 |
专业分类
林业 | 33篇 |
农学 | 24篇 |
基础科学 | 2篇 |
91篇 | |
综合类 | 39篇 |
农作物 | 43篇 |
水产渔业 | 107篇 |
畜牧兽医 | 209篇 |
园艺 | 9篇 |
植物保护 | 64篇 |
出版年
2023年 | 4篇 |
2022年 | 16篇 |
2021年 | 20篇 |
2020年 | 24篇 |
2019年 | 27篇 |
2018年 | 29篇 |
2017年 | 27篇 |
2016年 | 24篇 |
2015年 | 21篇 |
2014年 | 25篇 |
2013年 | 49篇 |
2012年 | 29篇 |
2011年 | 37篇 |
2010年 | 18篇 |
2009年 | 16篇 |
2008年 | 31篇 |
2007年 | 23篇 |
2006年 | 24篇 |
2005年 | 18篇 |
2004年 | 13篇 |
2003年 | 13篇 |
2002年 | 15篇 |
2001年 | 17篇 |
2000年 | 17篇 |
1999年 | 7篇 |
1998年 | 7篇 |
1997年 | 6篇 |
1996年 | 8篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1985年 | 6篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1973年 | 2篇 |
1971年 | 1篇 |
1968年 | 1篇 |
1956年 | 1篇 |
1952年 | 1篇 |
排序方式: 共有621条查询结果,搜索用时 15 毫秒
141.
Maria José GonçalvesMaria Teresa Cruz Ana Cristina TavaresCarlos Cavaleiro Maria Celeste LopesJorge Canhoto Lígia Salgueiro 《Industrial Crops and Products》2012,35(1):166-171
The essential oils from aerial parts of Thapsia minor Hoffmanns. & Link (Apiaceae), obtained by hydrodistillation, were analyzed by gas-chromatography and gas-chromatography-mass spectrometry. Oxygenated monoterpenes represented the main fraction with geranyl acetate (82.3-83.0%) as the major constituent, making this plant a good source of this compound.Biological activity of the essential oil was evaluated against several fungal strains. The highest activity was found against dermatophyte strains, Crytococcus neoformans and Candida guillermondii with minimal inhibitory concentrations values from 0.32 μl/ml to 1.25 μl/ml. The antifungal activity could be associated with the significant contribution of the oxygenated monoterpene geranyl acetate.Furthermore, this essential oil demonstrated to have potent anti-inflammatory in vitro activity, at concentrations that did not affect macrophages and keratinocytes viability, being the anti-inflammatory properties of the oil mainly due to geranyl acetate.These favorable results emphasize the antifungal and anti-inflammatory abilities of the molecule geranyl acetate and further support the exploitation of T. minor oil for pharmaceutical industry, in order to find new phytopharmaceuticals. 相似文献
142.
R. A. Silva L. Zambolim I. S. L. Castro H. S. Rodrigues C. D. Cruz E. T. Caixeta 《Euphytica》2018,214(9):153
The main phytosanitary problems affecting global coffee production are the fungal diseases known as rust, caused by Hemileia vastatrix Berkeley and Broome, and coffee berry disease (CBD), induced by Colletotrichum kahawae Waller and Bridge. The main disease control strategy is the use of resistant coffee cultivars. Híbrido de Timor is the most important source of resistant varieties used in breeding programs worldwide. The objective of this work was to characterize the diversity and disease resistance of 152 HdT genotypes from the germplasm collection at the Universidade Federal de Viçosa (UFV). Accessions were phenotyped with H. vastatrix races II and XXXIII. Molecular analysis was carried out with 29 random microsatellite markers or single sequence repeats (SSRs), and two SSRs associated with the CBD resistance gene Ck-1. All accessions in the germplasm collection were resistant to H. vastatrix race II, and 141 were resistant to H. vastatrix race XXXIII. Based on the presence of markers, there were 106 accessions containing the CBD resistance gene Ck-1. In the diversity study, the 152 accessions clustered into 21 different groups. A unique molecular profile (fingerprint) was determined for each individual, using 52 alleles from 22 SSR markers. The HdT germplasm of UFV was highly diverse, and included 99 accessions with multiple disease resistance genes, including the CBD resistance gene Ck-1, and others conferring resistance to H. vastatrix races II and XXXIII. 相似文献
143.
Development of a method to study the migration of six photoinitiators into powdered milk 总被引:2,自引:0,他引:2
Sanches-Silva A Pastorelli S Cruz JM Simoneau C Castanheira I Paseiro-Losada P 《Journal of agricultural and food chemistry》2008,56(8):2722-2726
The aim of the present work was to develop a rapid multimethod for the analysis of six photoinitiators (PIs) in powdered milk and to study the migration of these PIs from LDPE packaging into powdered milk. The optimized HPLC-DAD method showed high correlation coefficients (>0.9999) over a concentration range of 0.1-10.9 mg/L. The kinetics of migration of the photoinitiators from LDPE packaging into powdered milk were determined at different temperatures. The key parameters of migration phenomena (diffusion and partition coefficients) were determined. The diffusion coefficients at 5 degrees C ranged between 8.4 x 10(-12) (for ITX) and 5.1 x 10(-10) (for benzophenone) and those at 40 degrees C between 5.9 x 10(-10) (for ITX) and 6.1 x 10(-9) (for Irgacure 184). The diffusion coefficients of the six model migrants under study increased with temperature and showed a good Arrhenius relationship between 5 and 40 degrees C. 相似文献
144.
Hosne Ara Dilzahan Masaaki Yoshida Maya Umeda Michelle Ann Calubaquib Nolissa Delmo Organo Andre Freire Cruz 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2020,70(5):444-455
ABSTRACT This research focused on in vitro and in vivo biocontrol of two major rice diseases, Bacterial Leaf Blight caused by Xanthomonus oryzae pv oryzae (Xoo) and Sheath Blight caused by Rhizoctonia solani. Furthermore, the soil of paddy fields in Kansai region, Japan was analysed for the presence of these pathogens, and their microbial communities were evaluated according to the location and management systems. For biocontrol, the rhizospheric bacteria were isolated and molecularly identified. The results indicated that DAR17225040 and DAR17225017 were 99% similar to Bacillus aryabhattai and Bacillus megaterium. The isolated bacteria were able to suppress Bacterial Leaf Blight and Sheath Blight disease 78% and 86% respectively, under greenhouse conditions. The 16S amplicon sequencing (Illumina MiSeq 250bp) was used to analyse the bacterial community in paddy fields of soil taken from five locations under conventional and organic systems. Xoo and R. solani were detected in sampled soil, however, no clear difference was noted, regarding systems. From amplicon sequencing data, Chloroflexi, Acidobacteria, Proteobacteria, Actinobacteria, Planctomycetes were the dominant phyla of rice soil in Kansai region. The phylum Kazan-3B-28 was found more in organic system than conventional. The bacterial community was more affected by location and soil type than by management systems. 相似文献
145.
Libia Iris Trejo-Téllez J. Cruz García-Albarado David Méndez-Urbano Juan Antonio Pérez-Sato 《Journal of plant nutrition》2013,36(20):2547-2559
We analyzed the effect of substrate mixtures containing vermicompost (VC), tezontle (TZ), and pine bark (PB) in the following percentage proportions (v/v): T1: 00VC-20TZ-80PB; T2: 10VC-20TZ-70PB; T3: 20VC-20TZ-60PB; T4: 30VC-20TZ-50PB, plus two reference controls identified as T5: peat-moss (100%; PM) and T6: tree branch (TB) on growth and nitrogen concentration of Tillandsia flavobracteata and T. limbata. Tillandsia flavobracteata displayed the greatest height in T6 and T4, while the greatest height for T. limbata was obtained in T3. In T. flavobracteata the greatest number of leaves was obtained in T1, whereas in T. limbata no significant differences were found. Nitrogen was higher in T. limbata, especially when grown in T1 and T6. We were able to demonstrate that both Tillandsia species can grow and produce healthy plants under our experimental conditions, while the tested substrates differentially affected growth and nitrogen concentration in each species. 相似文献
146.
To study the mechanism of coffee melanoidin formation, green coffee beans were prepared by (1) removal of the hot water extractable components (WECoffee); (2) direct incorporation of sucrose (SucCoffee); and (3) direct incorporation of type II arabinogalactan-proteins (AGPCoffee). As a control of sucrose and AGP incorporation, lyophilized green coffee beans were also immersed in water (control). The original coffee and the four modified "in bean" coffee models were roasted and their chemical characteristics compared. The formation of material not identified as carbohydrates or protein, usually referred to as "unknown material" and related to melanoidins, and the development of the brown color during coffee roasting have distinct origins. Therefore, a new parameter for coffee melanoidin evaluation, named the "melanoidin browning index" (MBI), was introduced to handle simultaneously the two concepts. Sucrose is important for the formation of colored structures but not to the formation of "unknown material". Type II AGPs also increase the brown color of the melanoidins, but did not increase the amount of "unknown material". The green coffee hot water extractable components are essential for coffee melanoidin formation during roasting. The cell wall material was able to generate a large amount of "unknown material". The galactomannans modified by the roasting and the melanoidin populations enriched in galactomannans accounted for 47% of the high molecular weight brown color material, showing that these polysaccharides are very relevant for coffee melanoidin formation. 相似文献
147.
Zusammenfassung Eine Population der ersten Klongeneration mit einem eingefügten Kontrollsortiment wurde an vier Orten ausgepflanzt und durch
vier Züchter visuell nach der Methode der negativen Selektion selektiert. Es wurden signifikante Einflüsse der Orte, Jahre
und Züchter ermittelt. Die Effizienz kann durch die aktuelle Optimierung der Selektionsgrenzen anhand des Kontrollsortiments
erh?ht werden. Ausserdem wird erfolgreich praktiziert, die Populationen aus zwei Knollen je Genotyp zusammenzufügen oder im
Rahmen der internationalen Zusammenarbeit der L?nder des Rates für Gegenseitige Wirtschaftshilfe an zwei Orten auszupflanzen.
Summary A population of first clonal generation material was planted at four sites and selected visually by four breeders using the method of negative selection. Six table cultivars of potato that displayed appropriate levels of the characters under consideration, and six that did not, were planted at random throughout the population as standards. There were significant effects for site, year and breeder. The variance for sites was ca. 2 1/2 times that for the breeders (Tables 1 and 2), with about twice as many positive cultivars selected at site 1 as at site 3 (Table 3). There were also differences in selection results between breeders (Table 4). The uncertainty of visual selection of single plants is obvious from Table 5. Results from two years show a marked effect of year (Table 6). The relative frequencies of wrongly rejected (loss risk — Verlustrisiko) and wrongly selected (ballast risk — Ballastrisiko) standards are shown in Table 7. Only a few negative genotypes (standards) were selected, but there was a considerable loss of positive genotypes. The expected values of the standards and their actual selection results are being used to optimize the selection limits. The exploitation of populations can largely be ensured in bad years or sites, without the use of indicators and individual handling of clones with several tubers, by bulking two tubers per genotype from the first vegetative progeny. This measure may be restricted to highly valuable combinations. The possibility of accidentally selecting identical genotypes can be corrected in later generations simply by electrophoresis of soluble tuber proteins. Growing the population at two sites, best done through the framework of international co-operation, improves the likelihood of optimizing screening.相似文献
148.
A. Sanches Silva J. M. Cruz Freire R. Franz P. Paseiro Losada 《Journal of Cereal Science》2008,48(3):662-669
Cereals are widely consumed foodstuffs and it is therefore important to take them into account when estimating consumer exposure to packaging-related chemicals. The mass transport of three model migrants (diphenylbutadiene, triclosan and BHT) from low-density polyethylene (LDPE) within dry foodstuffs of different particle size (rice and wheat flour) was studied because of the relationship between consumer exposure and possible harmful effects on human health. The conditions that most affect the mass transport of substances within dry foods are evaluated and discussed. The diffusion coefficients (DF) for diphenylbutadiene (DPBD) and triclosan in the studied foodstuffs were estimated. The DF values for DPBD and triclosan in wheat flour at 25 °C were 7.1 × 10−8 cm2/s and 3.3 × 10−8 cm2/s, respectively. The DF values for DPBD and triclosan in rice at 25 °C were 4.7 × 10−8 and 4.3 × 10−8 cm2/s, respectively. BHT displayed different behaviour and other tests were therefore carried out to elucidate the associated mass transport process. 相似文献
149.
Costa Evely Giovanna Leite da Silva Fabiano Ferreira Silva Robério Rodrigues Porto Antonio Ferraz Santiago Bismarck Moreira Rocha Leone Campos Cruz Aline Gonçalves Guedes Anna Caroline Ferreira Neto Teotônio Martins Vieira Edvaldo Alves 《Tropical animal health and production》2019,51(8):2505-2511
Tropical Animal Health and Production - The objective of this study was to evaluate the inclusion of increasing levels of licuri meal as a substitute for soybean bran in the diet of pasture-based... 相似文献
150.
Peptide neurotoxins from fish-hunting cone snails 总被引:39,自引:0,他引:39
B M Olivera W R Gray R Zeikus J M McIntosh J Varga J Rivier V de Santos L J Cruz 《Science (New York, N.Y.)》1985,230(4732):1338-1343
To paralyze their more agile prey, the venomous fish-hunting cone snails (Conus) have developed a potent biochemical strategy. They produce several classes of toxic peptides (conotoxins) that attack a series of successive physiological targets in the neuromuscular system of the fish. The peptides include presynaptic omega-conotoxins that prevent the voltage-activated entry of calcium into the nerve terminal and release of acetylcholine, postsynaptic alpha-conotoxins that inhibit the acetylcholine receptor, and muscle sodium channel inhibitors, the mu-conotoxins, which directly abolish muscle action potentials. These distinct peptide toxins share several common features: they are relatively small (13 to 29 amino acids), are highly cross-linked by disulfide bonds, and strongly basic. The fact that they inhibit sequential steps in neuromuscular transmission suggests that their action is synergistic rather than additive. Five new omega-conotoxins that block presynaptic calcium channels are described. They vary in their activity against different vertebrate classes, and also in their actions against different synapses from the same animal. There are susceptible forms of the target molecule in peripheral synapses of fish and amphibians, but those of mice are resistant. However, the mammalian central nervous system is clearly affected, and these toxins are thus of potential significance for investigating the presynaptic calcium channels. 相似文献