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81.
Mingming Yu Lilibeth A. Salvador Sherwin K. B. Sy Yufei Tang Ravi S. P. Singh Qi-Yin Chen Yanxia Liu Jiyong Hong Hartmut Derendorf Hendrik Luesch 《Marine drugs》2014,12(3):1623-1640
A highly sensitive and specific LC-MS/MS method for the quantitation of largazole thiol, the active species of the marine-derived preclinical histone deacetylase inhibitor, largazole (prodrug), was developed and validated. Largazole thiol was extracted with ethyl acetate from human or rat plasma along with the internal standard, harmine. Samples were separated on an Onyx Monolithic C18 column by a stepwise gradient elution with 0.1% formic acid in methanol and 0.1% aqueous formic acid employing multiple reaction monitoring (MRM) detection. Linear calibration curves were obtained in the range of 12.5–400 ng/mL with 200 µL of human plasma. The overall intra-day precision was from 3.87% to 12.6%, and the inter-day precision was from 7.12% to 9.8%. The accuracy at low, medium and high concentrations ranged from 101.55% to 105.84%. Plasma protein bindings of largazole thiol in human and rat plasma as determined by an ultrafiltration method were 90.13% and 77.14%, respectively. Plasma drug concentrations were measured by this LC-MS/MS method. The pharmacokinetics of largazole thiol in rats was studied following i.v. administration at 10 mg/kg and found to follow a two-compartment model. Largazole thiol was rapidly eliminated from systemic circulation within 2 h. The established LC-MS/MS method is suitable for the analysis of largazole thiol in human plasma, as well. 相似文献
82.
TONG De-wen WANG Jin-yi Brain Patchett Ravi Gooneratne 《中国农业科学(英文版)》2006,5(10):793-797
Lolines are a group of saturated pyrrolizidine alkaloids that possess broad bioactivity against a wide array of herbivorous insects. However, they do not exhibit toxicity to ruminants such as cattle and sheep. In order to study the direct and potential physiological effects on ruminants and the mechanism of insecticide/insectifuge, the distribution of loline alkaloids in endophyte-infected meadow fescue and the seasonal change of the distribution were analyzed. The crowns, roots and leaves of endophyte-infected meadow fescue at its four different growth periods, i.e., spring, summer, early autumn and late autumn, in New Zealand were colleted. After powdering, organic solvent extraction and purification by column chromatography, all loline alkaloid samples were analyzed by capillary gas chromatography with 4-phenylmorpholine (PM) as an internal standard. The analytic results showed that the loline contents in the roots, crowns and leaves of endophyte-infected meadow fescue vary with seasons. Even within the same season, the distribution of lolines in endophyte-infected meadow fescue varies. During summer, lolines mainly existed in the leaves and roots, but in early autumn, they are produced in the crowns. It was concluded that, lolines were mainly produced in the leaves and roots of endophyte-infected meadow fescue. In gas chromatographic analysis, N-formylloline, the major component of loline alkaloid in the plant, was employed to assay the alkaloids. 相似文献
83.
84.
Short-term organic matter mineralisation following different types of tillage on a Swedish clay soil
Reduced tillage is proposed as a method of C sequestration in agricultural soils. However, tillage effects on organic matter turnover are often contradictory and data are lacking on how tillage practices affect soil respiration in northern Europe. This field study (1) quantified the short-term effects of different tillage methods and timing on soil respiration and N mineralisation and (2) examined changes in aggregate size distribution due to different tillage operations and how these relate to soil respiration. The study was conducted on Swedish clay soil (Eutric Cambisol) and compared no-tillage with three forms of tillage applied in early or late autumn 2010: mouldboard ploughing to 20–22 cm and chisel ploughing to 12 or 5 cm depth. Soil respiration, soil temperature, gravimetric water content, mineral N and aggregate size distribution were measured. The results showed that respiration was significantly higher (P?<?0.001) in no-till than in tilled plots during the 2 weeks following tillage in early September. Later tillage gave a similar trend but treatments did not differ significantly. Soil tillage and temperature explained 56 % of the variation in respiration. In the early tillage treatment, soil respiration decreased with tillage depth. Mineral N status was not affected by tillage treatment or timing. Soil water content did not differ significantly between tillage practices and therefore did not explain differences in respiration. The results indicate that conventional tillage in early autumn may reduce short-term soil respiration compared with chisel ploughing and no-till in clay soils in northern Europe. 相似文献
85.
Aki Sinkkonen Sari Kauppi Veera Pukkila Hui Nan Tomasz Płociniczak Merja Kontro Rauni Strömmer Martin Romantschuk 《Journal of Soils and Sediments》2013,13(8):1430-1438
Purpose
Previous investigations—field samplings and laboratory experiments—support the hypothesis that the degradation of s-triazines is enhanced in previously exposed as compared to pristine soils in terrestrial environments. Despite this, bottlenecks of soil sampling and various soil modification practices in microcosm studies have made it difficult to guarantee that previous contamination history enhances contaminant degradation regardless of soil origin in terrestrial ecosystems. We test the hypothesis that the degradation of simazine (2-chloro-4,6-bis(ethylamino)-s-triazine) is enhanced in previously exposed soils as compared to pristine soils in 10 l buckets at the mesocosm scale.Materials and methods
We collected soil at three separate sites consisting of a previously exposed and a pristine field. At every field, soil was collected at three separate plots and simazine degradation (days 0 and 65) and the response to atzB degrader gene primers (days 0 and 110) were followed. We analyzed the results using analysis of covariance (ANCOVA). Previous exposure and field site were assessed as fixed factors and initial simazine concentration and abiotic soil conditions as covariates.Results and discussion
After the 65-day exposure, remaining simazine concentrations depended on previous exposure but not on collection site. The response to atzB gene primers was positive in all mesocosms where simazine degradation had been rapid. Soil moisture, pH, and organic matter content were insignificant. If soil moisture was not included in the ANCOVA model, previous exposure did not appear as a significant factor.Conclusions
The results support the hypothesis that simazine is degraded more rapidly in previously exposed soils as compared to pristine environments, provided that degradation genes are available. Previously exposed soil might be used to enhance the degradation of simazine in recently contaminated terrestrial soils, supposing that the central requirements for microbial growth are adequate. 相似文献86.
Sorption and degradation are the primary processes controlling the efficacy and runoff contamination risk of agrochemicals. Considering the longevity of biochar in agroecosystems, biochar soil amendment must be carefully evaluated on the basis of the target agrochemical and soil types to achieve agricultural (minimum impact on efficacy) and environmental (minimum runoff contamination) benefits. In this study, sorption-desorption isotherms and kinetics of triazine (deisopropylatrazine) and organophosphorus (malathion, parathion, and diazinon) pesticides were first investigated on various soil types ranging from clayey, acidic Puerto Rican forest soil (PR) to heavy metal contaminated small arms range (SAR) soils of sandy and peaty nature. On PR, malathion sorption did not reach equilibrium during the 3 week study. Comparison of solution-phase molar phosphorus and agrochemical concentrations suggested that degradation products of organophosphorus pesticides were bound on soil surfaces. The degree of sorption on different soils showed the following increasing trend: deisopropylatrazine < malathion < diazinon < parathion. While sorption of deisopropylatrazine on SAR soils was not affected by diazinon or malathion, deisopropylatrazine suppressed the sorption of diazinon and malathion. Deisopropylatrazine irreversibly sorbed on biochars, and greater sorption was observed with higher Brunauer-Emmett-Teller surface area of biochar (4.7-2061 mg g(-1)). The results suggested the utility of biochar for remediation of sites where concentrations of highly stable and mobile agrochemicals exceed the water-quality benchmarks. 相似文献
87.
Jin Hee Park Nanthi Bolan Mallavarapu Megharaj Ravi Naidu 《Water, air, and soil pollution》2012,223(2):599-608
Lead forms stable compounds with phosphate and the immobilized Pb becomes less available to soil biota. In this study, we
tested the bioavailabilty of Pb using earthworms (Eisenia fetida) and plants after immobilization of Pb by a soluble P compound and an insoluble rock phosphate compound in the presence of
phosphate-solubilizing bacteria (Enterobacter sp.). Rock phosphate in the presence of phosphate-solubilizing bacteria and a soluble P compound enhanced Pb immobilization
as measured by NH4NO3-extractable Pb concentration, thereby reduced its bioavailability as evaluated by earthworm Pb loading and sunflower (Helianthus annuus) Pb uptake under greenhouse conditions. However, soluble P treatment increased the concentration of Pb in soil solution thereby
inhibited the root elongation of mustard (Brassica hirta) seedlings. Sunflower plants in the Pb-spiked soil without P amendments showed symptoms of necrosis and stunting because
of Pb toxicity. Both soluble and insoluble P treatments significantly increased shoot and root weight and decreased Pb concentration
in shoot by more than 50% compared to the control. However, high Pb concentration in soil solution was found in soluble P
treatment, which can be attributed to dissolved organic carbon–Pb complex formation, thereby increasing Pb mobility. The inoculation
of phosphate-solubilizing bacteria can facilitate phytostabilization of Pb-contaminated site. 相似文献
88.
P. Arumugam D. Inbakandan M. S. Ramasamy M. Murugan 《Journal Of Applied Aquaculture》2013,25(3):265-270
Abstract Liposomes were prepared in the laboratory with lipids obtained from chicken egg yolk to encapsulate Spirulina powder. Artemia napulii were hatched and fed with lipid-encapsulated Spirulina or Spirulina powder. After 20 days of rearing, the experimental A. salina were harvested and measured for total body length and total content of protein and carbohydrates. Total body length was 45% higher, protein content was 49% higher, and carbohydrate was 35% higher in Artemia fed with liposomes as compared with those fed only Spirulina powder. 相似文献
89.
The effect of different nutrient media on growth, physicochemical, and agar properties of the marine algae Gracilaria cliftonii was investigated in ocean water (OW) and inland saline water (ISW). G. cliftonii fronds were cultured in 500-mL and 25-L containers with different nutrient media: Aquasol, Total, Guillard f2, Walnes, and Modified-Provasoli's Enriched Seawater in OW and ISW at 35 ppt. Specific growth rate (SGR) was higher in OW than ISW irrespective of nutrient media in both volumes. Growth of G. cliftonii in Guillard f2-supplemented OW was significantly higher than other nutrient media in both water types. Nutrient media had no influence on growth and agar properties. However, f2?supplemented OW resulted in significantly higher agar yield (58.3% db) as compared to other media. Either f2 or Walnes media are preferred nutrient sources for culturing G. cliftonii in ocean and inland saline water. 相似文献
90.
Feed rate is one of the important variables considered for the improvement in production of prawns. The effects of four feeding rates on growth, water quality and the nutrient budget of Penaeus latisulcatus were investigated for 98 days. The specific growth rate (SGR) at 3.0% feed rate was significantly higher than at all higher feed rates, and there was no significant difference in SGR between 4.5%, 6% and 7.5%. Total ammonia nitrogen concentrations in all treatments remained low in the safe range for prawn culture. Dissolved inorganic nitrogen and nitrate nitrogen were significantly higher (P < 0.05) in prawn tanks received feed rates of 6.0% and 7.5%. Total phosphorus and the soluble reactive phosphorus linearly increased with the progression of the trial and feeding rates. Nutrient conversion rates were significantly higher (P < 0.05) in prawns receiving the feeding rate of 3.0% than feeding rates of 6.0% and 7.5%. The lowest food conversion ratio was recorded at feeding rates of 3% and 4.5%. Nutrient budget showed that 6.01–15.99% nitrogen and 4.53–9.29% phosphorus of the nutrient inputs were retained in the prawn biomass. The results indicated that the growth and nutrient conversion rate may not increase with the increase above 3.0% of biomass per day. 相似文献