全文获取类型
收费全文 | 520篇 |
免费 | 37篇 |
国内免费 | 1篇 |
专业分类
林业 | 43篇 |
农学 | 14篇 |
基础科学 | 1篇 |
64篇 | |
综合类 | 94篇 |
农作物 | 13篇 |
水产渔业 | 42篇 |
畜牧兽医 | 246篇 |
园艺 | 11篇 |
植物保护 | 30篇 |
出版年
2024年 | 2篇 |
2023年 | 7篇 |
2022年 | 5篇 |
2021年 | 22篇 |
2020年 | 27篇 |
2019年 | 27篇 |
2018年 | 10篇 |
2017年 | 25篇 |
2016年 | 12篇 |
2015年 | 14篇 |
2014年 | 22篇 |
2013年 | 27篇 |
2012年 | 36篇 |
2011年 | 44篇 |
2010年 | 18篇 |
2009年 | 16篇 |
2008年 | 35篇 |
2007年 | 37篇 |
2006年 | 29篇 |
2005年 | 32篇 |
2004年 | 21篇 |
2003年 | 20篇 |
2002年 | 17篇 |
2001年 | 5篇 |
2000年 | 6篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 5篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1971年 | 2篇 |
1969年 | 1篇 |
1948年 | 1篇 |
1898年 | 2篇 |
排序方式: 共有558条查询结果,搜索用时 31 毫秒
91.
92.
A comparison between marine and terrestrial invertebrate meals for mirror carp (Cyprinus carpio) diets: Impact on growth,haematology and health
下载免费PDF全文
![点击此处可从《Aquaculture Research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Invertebrate meals (e.g. polychaetes and insects) present novel and sustainable high‐quality nutrient sources for use in fish feed formulations. To test this innovative source, an eleven‐week feeding trial was conducted evaluating the effects of replacing the fishmeal (FM) component as an example of a superior protein source (FM CTRL) with ragworm meal (RW, Nereis virens) and/or silkworm pupae (SWP, Bombyx mori) in mirror carp (Cyprinus carpio) diets. Three experimental diets with partial replacement of FM (diets: RW + FM, SWP + FM and RW + SWP + FM) were formulated. All diets were formulated to be iso‐nitrogenous, iso‐lipidic and iso‐energetic. Growth performance and feed utilization indices were assessed, and the feeding trial concluded with the analysis of haematological parameters to provide an indication of carp physiological and health status. Mean weight gain was greatest in mirror carp fed RW + FM (60.83 fish?1 day?1; P < 0.05 vs. all other diets) followed by SWP + FM (40.62 g fish?1 day?1; P < 0.05 vs. all other diets). The least weight gain was achieved in fish fed FM + SWP + RW+ and FM CTRL (34.34 and 33.96 g fish?1 day?1, respectively; not significantly different from each other). Fish fed on RW + FM diet had significantly lower plasma ammonia concentrations than any other dietary groups (P = 0.04). Mirror carp fed on SWP + FM diet (111.52 units mL?1) were observed to have a marked enhancement in alternative complement activity than FM CTRL (79.21 units mL?1, P = 0.041). Both ragworm and silkworm pupae meal present attractive sustainable functional feed component in carp diets, with benefits on enhancing growth performance and specific physiological parameters. 相似文献
93.
Andrei V. Grinchenko Alex von Kriegsheim Nikita A. Shved Anna E. Egorova Diana V. Ilyaskina Tatiana D. Karp Nikolay V. Goncharov Irina Y. Petrova Vadim V. Kumeiko 《Marine drugs》2021,19(12)
C1q domain-containing (C1qDC) proteins are a group of biopolymers involved in immune response as pattern recognition receptors (PRRs) in a lectin-like manner. A new protein MkC1qDC from the hemolymph plasma of Modiolus kurilensis bivalve mollusk widespread in the Northwest Pacific was purified. The isolation procedure included ammonium sulfate precipitation followed by affinity chromatography on pectin-Sepharose. The full-length MkC1qDC sequence was assembled using de novo mass-spectrometry peptide sequencing complemented with N-terminal Edman’s degradation, and included 176 amino acid residues with molecular mass of 19 kDa displaying high homology to bivalve C1qDC proteins. MkC1qDC demonstrated antibacterial properties against Gram-negative and Gram-positive strains. MkC1qDC binds to a number of saccharides in Ca2+-dependent manner which characterized by structural meta-similarity in acidic group enrichment of galactose and mannose derivatives incorporated in diversified molecular species of glycans. Alginate, κ-carrageenan, fucoidan, and pectin were found to be highly effective inhibitors of MkC1qDC activity. Yeast mannan, lipopolysaccharide (LPS), peptidoglycan (PGN) and mucin showed an inhibitory effect at concentrations three orders of magnitude greater than for the most effective saccharides. MkC1qDC localized to the mussel hemal system and interstitial compartment. Intriguingly, MkC1qDC was found to suppress proliferation of human adenocarcinoma HeLa cells in a dose-dependent manner, indicating to the biomedical potential of MkC1qDC protein. 相似文献
94.
Potato (Solanum tuberosum L.) is a major food and cash crop mainly grown by small-scale farmers in the highland regions of Uganda. Changing global weather patterns require varieties that are able to grow within the short rainfall cycles and yield optimally under the prevailing conditions. The objectives of this study were to estimate the combining ability effects for early maturity, yield and yield related traits in potato. Eighteen F1 families generated from two sets of 12 parents using a North Carolina Design II were evaluated for days to 50% flowering, leaf senescence, yield and yield related traits in two different locations. Both additive and non-additive genetic effects influenced the expression of traits. However, additive genetic effects were predominant over the non-additive for most of the traits. The GCA/SCA ratios were 0.68 and 0.78 for days to 50% flowering and average tuber weight. Broad sense heritability estimates were 0.70 for total tuber weight and 0.78 for days to 50% flowering. The predominance of additive genetic effects imply that, genetic gains can be achieved through different selection methods and traits transferred to the respective progenies. Parents Rwangume, 396,038.107, 395,011.2, NKRK19.17, 393,077.54, Kimuri, and 392,657.8 had desirable GCA effects for the number of days to flowering and yield related traits. Families of Rwangume?×?NKRK19.17, 393,077.54?×?395,011.2, 396,038.107?×?Rwangume and 396,038.107?×?395,011.2 had desirable SCA effects for yield and number of days to 50% flowering. The selected parents and families will be subjected to further clonal evaluation and selection. 相似文献
95.
Angelia S. M. Vanderlaan Alex R. Hanke Joël Chassé John D. Neilson 《Fisheries Oceanography》2014,23(1):83-100
The Atlantic bluefin tuna (Thunnus thynnus) population in the western Atlantic supports substantial commercial and recreational fisheries. Despite quota establishment and management under the auspices of the International Commission for the Conservation of Atlantic Tunas, only small increases in population growth have been estimated. In contrast to other western bluefin tuna fisheries indices, contemporary estimates of catch per unit effort (CPUE) in the southern Gulf of St. Lawrence have increased rapidly and are at record highs. This area is characterized by the Cold Intermediate Layer (CIL) that is defined by waters <3°C and located at depths of 30–40 m in September. We investigated the influence of several in situ environmental variables on the bluefin tuna fishery CPUE using delta‐lognormal modelling and relatively extensive and consistent oceanographic survey data, as well as dockside monitoring and mandatory logbook data associated with the fishery. Although there is considerable spatial and temporal variation of water mass characteristics, the amount of available habitat in the southern Gulf of St. Lawrence (assuming a > 3°C thermal ambit) for bluefin tuna has been increasing. The percentage of the water column occupied by the CIL was a significant environmental variable in the standardization of CPUE estimates. There was also a negative relationship between the spatial extents of the CIL and the fishery. Properties of the CIL account for variation in the bluefin tuna CPUE and may be a factor in determining the amount of available feeding habitat for bluefin tuna in the southern Gulf of St. Lawrence. 相似文献
96.
Gabriele Vaccari Cynthia H. Panagiotidis Cristina Acin Simone Peletto Francis Barillet Pierluigi Acutis Alex Bossers Jan Langeveld Lucien van Keulen Theodoros Sklaviadis Juan J. Badiola Olivier Andr��oletti Martin H. Groschup Umberto Agrimi James Foster Wilfred Goldmann 《Veterinary research》2009,40(5)
Scrapie is a fatal, neurodegenerative disease of sheep and goats. It is also the earliest known member in the family of diseases classified as transmissible spongiform encephalopathies (TSE) or prion diseases, which includes Creutzfeldt-Jakob disease in humans, bovine spongiform encephalopathy (BSE), and chronic wasting disease in cervids. The recent revelation of naturally occurring BSE in a goat has brought the issue of TSE in goats to the attention of the public. In contrast to scrapie, BSE presents a proven risk to humans. The risk of goat BSE, however, is difficult to evaluate, as our knowledge of TSE in goats is limited. Natural caprine scrapie has been discovered throughout Europe, with reported cases generally being greatest in countries with the highest goat populations. As with sheep scrapie, susceptibility and incubation period duration of goat scrapie are most likely controlled by the prion protein (PrP) gene (PRNP). Like the PRNP of sheep, the caprine PRNP shows significantly greater variability than that of cattle and humans. Although PRNP variability in goats differs from that observed in sheep, the two species share several identical alleles. Moreover, while the ARR allele associated with enhancing resistance in sheep is not present in the goat PRNP, there is evidence for the existence of other PrP variants related to resistance. This review presents the current knowledge of the epidemiology of caprine scrapie within the major European goat populations, and compiles the current data on genetic variability of PRNP. 相似文献
97.
TM Sipriani F Grandi LCG da Silva PC Maiorka CI Vannucchi 《Reproduction in domestic animals》2009,44(S2):137-140
Development of the foetal respiratory system includes both pulmonary growth and maturation. In human medicine, a higher incidence of respiratory distress is reported in newborn males. This study aimed to identify different phases of canine foetal lung maturation throughout pregnancy, to determine the stage of pregnancy in which surfactant production begins and to compare pulmonary development of male and female foetuses. Pregnant bitches (34) were subjected to elective ovariohysterectomy and allocated into four groups, according to the stage of pregnancy: 30–40 days of pregnancy (n = 10), 41–50 days (n = 10), 51–60 days (n = 10) and bitches in the first stage of parturition (n = 4). Foetal lungs were histologically processed and evaluated by optical microscopy. The pseudoglandular phase was identified between the 35th day and 46th day of gestation; the onset of canalicular and saccular periods was observed, respectively, from the 48th day and 60th day of pregnancy. Lungs from foetuses at term were in the saccular phase; thus, the development into the alveolar period occurs in the neonatal period. The histological analyses revealed that respiratory tract development is centrifugal, from upper to lower airways. Therefore, it is possible to identify distinct development periods in different portions of the same organ. In conclusion, the saccular phase of lung development begins around 57 and 60 days of pregnancy, the period in which surfactant production is believed to occur. Male and female foetuses present similar pulmonary development from early pregnancy until parturition. 相似文献
98.
99.
Using statistical experimental design, the effects of multi-stage hot drawing process on thermal shrinkage and crystallographic
order of linear aliphatic-aromatic co-polyester fibres were statistically analyzed. Thermal shrinkage and fullwidth half-maximum
(FWHM) of an X-ray scattering profile of the fibres have been quantitatively assessed, and the direction of increasing or
decreasing the significant process parameters has been characterized. It has been found that the number of drawing stages,
drawing temperature and relaxing stage ratio affect the shrinkage and crystallographic order together. Plate temperature and
the interaction between drawing stages and drawing temperature or drawing ratio have an effect on thermal shrinkage; Spin
finish application and relaxing temperature have an effect on crystallographic order. The data analysis has been characterized
with regard to the relationship between the studied factors statistically analyzed and the scientific reasons suggested. Factorial
statistical analysis simulates the combination of drawing process parameters and the selected as-spun environmentally friendly
biodegradable fibre. 相似文献
100.
John E. Major Alex MosselerDebby C. Barsi Britt Corriveau-DupuisMoira Campbell 《Forest Ecology and Management》2009
Our goal was to quantify and compare the impact of three silvicultural treatments (STs) on growth, light-energy processing, and needle-level morphological adaptive traits for eastern white pine (Pinus strobus L.) from large, central Ontario (ON) and small, isolated Newfoundland (NL) populations. The interest in STs is to reduce weevil (Pissodes strobi) incidence; however, there are potential adaptive changes and productivity trade-offs. The light levels for the STs were, on average, 100%, 42.0%, and 20.4% transmittance for the full-sun, and intermediate- and high-shade STs, respectively. After 8 years, overall height growth was 4.10, 3.25, and 1.70 m for full-sun, and intermediate- and high-shade STs, respectively (P < 0.001). Across all STs, ON populations had greater total height (14%), basal diameter (12%), current leader length (25%), and tree volume (49%) than NL populations (all P < 0.001). At low light levels (10 and 25 μmol m−2 s−1), high-shade ST trees had higher photochemical quenching (qP) and lower chlorophyll fluorescence (Fpc) compared with intermediate-shade and full-sun STs. At 100 μmol m−2 s−1 and beyond, full-sun ST trees had higher qP and lower Fpc than intermediate- and high-shade STs. Average total chlorophyll concentration (CHL) and content (CHLC), and carotenoid concentration (CAR), increased in response to the intermediate-shade ST but did not respond further, or decreased in the high-shade ST. Region was significant for CHL, CAR, chlorophyll a:b and CHL:CAR ratios and CHLC, with ON greater than NL, but was reversed for CHL:CAR ratio. Tree height and volume showed a curvilinear and linear relationship to light level, respectively. Tree height showed a positive linear relationship to qP, apparent photosynthesis, chlorophyll a:b ratio, and needle N (all P < 0.001). Tree height showed a negative linear relationship to Fpc, CHL:CAR ratio, specific needle area, C:N ratio, and needle area N−1 (all P < 0.001). There were modest trade-offs between weevil protection and productivity in the intermediate ST due to the compensatory physiological and morphological adaptations to the limiting light, however, the trade-off with growth at the high-shade level was severe. For NL, consideration should now be given to the introduction and mixing of seed from local seed sources with more southern mainland seed sources, which would decrease the inbreeding effect and provide wider variation for natural selection for a more fit future population. 相似文献