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91.
92.
Desktop classification of inland wetlands for systematic conservation planning in data‐scarce countries: mapping wetland ecosystem types,disturbance indices and threatened species associations at country‐wide scale
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Heidi van Deventer Jeanne Nel Namhla Mbona Nancy Job Justine Ewart‐Smith Kate Snaddon Ashton Maherry 《水产资源保护:海洋与淡水生态系统》2016,26(1):57-75
93.
Kilcoyne J Keogh A Clancy G LeBlanc P Burton I Quilliam MA Hess P Miles CO 《Journal of agricultural and food chemistry》2012,60(10):2447-2455
Azaspiracids are a group of lipophilic polyether toxins produced by the small dinoflagellate Azadinium spinosum. They may accumulate in shellfish and can result in illnesses when consumed by humans. Research into analytical methods, chemistry, metabolism, and toxicology of azaspiracids has been severely constrained by the scarcity of high-purity azaspiracids. Consequently, since their discovery in 1995, considerable efforts have been made to develop methods for the isolation of azaspiracids in sufficient amounts and purities for toxicological studies, in addition to the preparation of standard reference materials. A seven-step procedure was improved for the isolation of azaspiracids-1-3 (1, 2, and 3) increasing recoveries 2-fold as compared to previous methods and leading to isolation of sufficiently purified azaspiracid-6 (6) for structural determination by NMR spectroscopy. The procedure, which involved a series of partitioning and column chromatography steps, was performed on 500 g of Mytilus edulis hepatopancreas tissue containing ~14 mg of 1. Overall yields of 1 (52%), 2 (43%), 3 (43%), and 6 (38%) were good, and purities were confirmed by NMR spectroscopy. The structure of 6 was determined by one- and two-dimensional NMR spectroscopy and mass spectrometry. The stability of 6 relative to 1 was also assessed in three solvents in a short-term study that demonstrated the greatest stability in aqueous acetonitrile. 相似文献
94.
Xie C Yu K Zhong D Yuan T Ye F Jarrell JA Millar A Chen X 《Journal of agricultural and food chemistry》2011,59(20):11078-11087
Ultraperformance liquid chromatography coupled with hybrid quadrupole/ion mobility/orthogonal acceleration time-of-flight (oa-TOF) mass spectrometry (UPLC-IM-MS) was used to study the isomeric transformations of trans-5-caffeoylquinic acid, an extremely active compound present in multiple vegetables, fruits, and beverages. The UPLC/oa-TOF MS results proved that in phosphate buffer (pH 7.4), plasma, or urine sample, trans-5-caffeoylquinic acid first isomerizes to trans-4-caffeoylquinic acid and then to trans-3-caffeoylquinic acid by intramolecular acyl migration. When exposed to UV light, trans-3-, -4-, and -5-caffeoylquinic acids undergo cis/trans isomerization to form cis isomers. The isomerization was solely dependent on the pH of the matrix, as well as the incubation temperature, and was independent of metabolic enzymes. UPLC-IM-MS results revealed that a reversible cis/trans isomerization of caffeoylquinic acids could also be induced by the electric field in an electrospray source. Thus, understanding the possible role of electric field-induced isomerization of caffeoylquinic acids may help lessen the confusion between gas phase phenomena and liquid state chemistry when applying IM-MS analysis. The comprehensive understanding of caffeoylquinic acid isomerization transformations is crucial for the appropriate handling of samples and interpretation of experimental data. 相似文献
95.
Martin Guillot Kate Alexander Candido Pomar Jrme R.E. del Castillo 《Research in veterinary science》2011,90(3):484-490
We studied in growing pigs the effects of exposure to dietary chlortetracycline on bone mineral density (BMD) and bone color. Pigs were randomly allocated to a drug-free diet (n = 48) or a diet fortified with 800 ppm of chlortetracycline, starting either at 28- or 84-d of age, and for either a 28- or 56-d duration (n = 16 pigs/group). The lumbar vertebral discoloration and BMD of randomly chosen pigs were evaluated at 28-d intervals up to 168-d of age. The odds of bone discoloration increased with dosing duration and age at treatment onset, and decreased with the withdrawal time and age at treatment onset interaction (p ? 0.001). The measured trabecular BMD linearly increased with age and squared treatment duration (p ? 0.005). Therefore, TC-induced bone discoloration is reversible, and may be prevented with proper dosing regimen design. Moreover, TC induces a persistent increase on BMD that could be detected with quantitative computed tomography. 相似文献
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Kateřina Pánková Zbyněk Milec James Simmonds Michelle Leverington-Waite Lesley Fish John W. Snape 《Euphytica》2008,164(3):779-787
The single chromosome substitution lines of chromosome 3B of the Czech alternative wheat variety Česká Přesívka (CP 3B) into
two spring varieties Zlatka and Sandra, revealed clear differences in flowering time compared to the recipient varieties.
To map this gene(s), recombinant substitution lines for chromosome 3B were produced from crosses of the substitution lines
with their recipient parents and genetic maps developed using SSR markers. Two populations were mapped, Sandra//Sandra 3B/Sandra
(CP 3B) and Zlatka//Zlatka/Zlatka (CP 3B). Combining the genotype data with phenotype data on flowering time in five independent
experiments under natural long day or controlled short day conditions revealed a single flowering time QTL. This gene had
an additive effect of 1–6 days, depending on environment and genetic background, and was mapped in both populations to a position
in the region of marker Xbarc164 near the centromere on the long arm of 3B. Comparisons of the genetic maps with other 3B maps developed by the authors indicated
that the QTL may be homologous to a QTL segregating in UK germplasm. 相似文献
99.
Anthropogenic radioisotopes with long physicalhalf-lives derived from atmospheric fallout remain inthe environment for decades after deposition. Process- and field-based studies within uplandcatchments show that radiocaesium is transported insolution as well as in particulate form. Catchmenthydrology is therefore an important control onradiocaesium transport and natural processes of soildevelopment. The topographic index, from thehydrological model TOPMODEL, has been used as a basisfor the development of a simple model for predictingradiocaesium redistribution in temperate uplandcatchments. The model is particularly suited topredicting 137Cs redistribution within uplandenvironments as it is based on topography, which isreadily calculated from digital terrain models withingeographical information systems. A conceptual modelof radiocaesium losses on hillslopes and re-depositionon the valley floor was calibrated with atmosphericweapons testing 137Cs inventories from soil coredata for the Raithburn catchment, Renfrewshire, U.K. The model fitted the observations well and showed thatin this catchment a topographic index value of about5.0, for 10 m grid cells, forms the threshold between137Cs loss and accumulation. The resultsindicated that about 20% of the total atmosphericweapons testing 137Cs deposited in the catchmenthad been transported out of the catchment over theca. 30 yr period since deposition. 相似文献
100.
Sample of longissimus muscle were taken from carcasses of steers, steers implanted with anabolic agents and bulls of Friesian and Charolais X Friesian breeds of cattle. Percent and mean cross-sectional areas (CSA) of three myofiber types (beta R, alpha R and alpha W) were determined. The percentage of beta R myofibers did not vary significantly with treatment. The implanted steers had 26% more alpha R and 8% less alpha W myofibers than the untreated steers, while the bulls had 33% more alpha R and 20% less alpha W myofibers than the implanted steers (P less than .001). In the implanted steers the mean CSA of the beta R myofibers was significantly greater than that of the untreated steers, but did not differ from that of the bull. The mean CSA of the alpha R myofibers increased considerably with treatment, but only that of the bull was significantly greater than that of the untreated steers. The mean CSA of the alpha W myofibers in the implanted steers was identical with that of the untreated steers and significantly smaller than that of the bulls. In comparison to the untreated steers, significant hypertrophy of all three myofiber types occurred in bulls. These findings demonstrate a significant increase in the oxidative capacity of the longissimus when the levels of both endogenous and exogenous anabolic agents are increased. They are also consistent with the greater efficiency of deposition of protein obtained with implanted steers and bulls.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献