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排序方式: 共有1004条查询结果,搜索用时 15 毫秒
81.
Courtney Ann Welch Gary D. Potter Pete G. Gibbs Elena M. Eller 《Journal of Equine Veterinary Science》2012,32(1):60-64
This study was conducted to study absorption of glucosamine (GlucN) and chondroitin sulfate (CS) in horses immediately after feeding. Six mature mares were used in a replicated 3 × 3 Latin-square-designed experiment. The experiment consisted of three 15-day periods, which included 10 days of diet adaptation followed by a 5-day sampling period. Blood was drawn after feeding on one day during each sampling period. Horses were fed a control diet (40% hay, 60% concentrate) balanced to meet NRC requirements for maintenance of mature horses (NRC, Nutrient requirements of horses, 1989). In one experimental diet, 2.0 g CS and 5.5 g GlucN were added to the basal ration at each feeding. In the other experimental diet, 3.5 g CS and 8.5 g GlucN were added to the basal ration at each feeding. After collections, blood was centrifuged and plasma was harvested and stored until analyzed for the presence of each compound. Analyses for plasma GlucN were performed using high-performance liquid chromatography. CS in the plasma was analyzed using a color reagent, dimethylmethylene blue, followed by ultraviolet spectrophotometry. There were no significant differences (P < .05) in the concentration of either CS or GlucN in plasma, when comparing the three different diets. This leads to a conclusion that these compounds were not absorbed intact through the intestinal wall into the bloodstream. This poses a question as to whether oral forms of these compounds are absorbed and are able to migrate to joints through the blood to improve joint function. 相似文献
82.
To improve the silvicultural targets for ecologically sustainable forestry, we quantified functionally important structural features for the first time in a representative set of old-growth forests in hemiboreal Europe. Altogether, 23 old-growth stands of four site-type groups were compared with mature commercial stands nearby in the Estonian state forests that hold the Forest Stewardship Council (FSC) certificate of sustainable forestry. These two treatments did not differ significantly in terms of tree-species diversity, volumes of woody debris of <20 cm diameter (including fine woody debris) and its decay-stage composition. However, mature stands had many more early-successional trees and lacked late-successional deciduous species; they also had a higher overall density and volume of live trees, due to abundant individuals of 10–39 cm diameter at breast height. Old-growth stands had at least twice as many live trees ≥40 cm, standing dead trees ≥30 cm and lying wood ≥20 cm in diameter, any freshly fallen debris, and regeneration. For lying wood ≥20 cm in diameter, the treatment effect depended on site type: both treatments of Vaccinium-type dry boreal forests were remarkably deadwood-poor (indicating historical management of the old-growth stands), while mature eutrophic stands of Aegopodium-type were most impoverished relative to old-growth levels. We conclude that many functional characteristics of old growth were present in the FSC-certified, mostly naturally regenerated, commercial stands. The main problem is the lack of very large trees, particularly of late-successional deciduous species, which should be addressed by their well-planned retention in cut areas and reconsideration of salvage logging strategies. A dense regeneration in old-growth stands also indicated the potential of selection cuttings. The study highlighted the need for region- and site-type specific numerical targets for sustainable forest management, which in the hemiboreal region should address the characteristic occurrence of late-successional deciduous trees on fertile soils and higher natural deadwood volumes than in typical boreal forests. For certification, the issues of structural impoverishment revealed both the inadequacy of some silvicultural practices and some indicators set by the national FSC-standard in Estonia. 相似文献
83.
Campbell JK Rogers RB Lila MA Erdman JW 《Journal of agricultural and food chemistry》2006,54(3):747-755
This work describes the development and utilization of a plant cell culture production approach to biosynthesize and radiolabel phytoene and phytofluene for prostate cancer cell culture studies. The herbicide norflurazon was added to established cell suspension cultures of tomato (Lycopersicon esculentum cv. VFNT cherry), to induce the biosynthesis and accumulation of the lycopene precursors, phytoene and phytofluene, in their natural isomeric forms (15-cis-phytoene and two cis-phytofluene isomers). Norflurazon concentrations, solvent carrier type and concentration, and duration of culture exposure to norflurazon were screened to optimize phytoene and phytofluene synthesis. Maximum yields of both phytoene and phytofluene were achieved after 7 days of treatment with 0.03 mg norflurazon/40 mL fresh medium, provided in 0.07% solvent carrier. Introduction of 14C-sucrose to the tomato cell culture medium enabled the production of 14C-labeled phytoene for subsequent prostate tumor cell uptake studies. In DU 145 prostate tumor cells, it was determined that 15-cis-phytoene and an oxidized product of phytoene were taken up and partially metabolized by the cells. The ability to biosynthesize, radiolabel, and isolate these carotenoids from tomato cell cultures is a novel, valuable methodology for further in vitro and in vivo investigations into the roles of phytoene and phytofluene in cancer chemoprevention. 相似文献
84.
Anodic Fenton treatment (AFT) has been shown to be a promising technology in pesticide wastewater treatment. However, no research has been conducted on the AFT application to contaminated soils. In this study, the 2,4-D degradation kinetics of AFT in a silt loam soil slurry were investigated for the first time, and the effects of various experimental conditions including initial 2,4-D concentration, Fenton reagent delivery rate, amount of humic acid (HA) addition, and pH were examined. The 2,4-D degradation in soil slurry by AFT was found to follow a two-stage kinetic model. During the early stage of AFT (the first 4-5 min), the 2,4-D concentration profile followed a pseudo-first-order kinetic model. In the later stage (typically after 5 or 6 min), the AFT kinetic model provided a better fit. This result is most likely due to the existence of (*)OH scavengers and 2,4-D sorption on soil. The Fe(2+) delivery rate was shown to be a more significant factor in degradation rate than the H(2)O(2) delivery rate when the Fe(2+)/H(2)O(2) ratios were in the range of 1:2 to 1:10. The presence of HA in soil lowered the AFT rate, most probably due to the competition with 2,4-D for consumption of (*)OH and increased sorption of 2,4-D on soil. The optimal pH for 2,4-D degradation in soil slurry by AFT was observed to be in the range of pH 2-3. 相似文献
85.
Lu CH Engelmann NJ Lila MA Erdman JW 《Journal of agricultural and food chemistry》2008,56(17):7710-7714
Radioisotope-labeled lycopene is an important tool for biomedical research but currently is not commercially available. A tomato cell suspension culture system for the production of radioisotope-labeled lycopene was previously developed in our laboratory. In the current study, the goal was to optimize the lycopene extraction efficiency from tomato cell cultures for preparatory high-performance liquid chromatography (HPLC) separation. We employed response surface methodology (RSM), which combines fractional factorial design and a second-degree polynomial model. Tomato cells were homogenized with ethanol, saponified by KOH, and extracted with hexane, and the lycopene content was analyzed by HPLC-PDA. We varied five factors at five levels: ethanol volume (1.33-4 mL/g); homogenization period (0-40 s/g); saturated KOH solution volume (0-0.67 mL/g); hexane volume (1.67-3 mL/g); and vortex period (5-25 s/g). Ridge analysis by SAS suggested that the optimal extraction procedure to extract 1 g of tomato cells was at 1.56 mL of ethanol, 28 s homogenization, 0.29 mL of KOH, 2.49 mL of hexane, and 17.5 s vortex. These optimal conditions predicted by RSM were confirmed to enhance lycopene yield from standardized tomato cell cultures by more than 3-fold. 相似文献
86.
Ann Barrett Menexia Tsoubeli Paul Maguire Nora Beck Tan Karen Conca Yoa Wang Bill Porter Irwin Taub 《Cereal Chemistry》2000,77(6):784-790
Effects of formulation on the textural stability of intermediate‐moisture, flour‐based, “jerky”‐type extrudates were assessed. Potato‐based extrudates containing various particulate‐meat concentrations and different plasticizers (sucrose, fructose, glycerol, and glucose) were produced and subjected to accelerated storage for three weeks. The elastic modulus of the samples was measured before storage and then weekly. The relative fluidity and moisture mobility of the specimens were assessed by dynamic mechanical spectrometry (DMS), electron spin resonance (ESR), and nuclear magnetic resonance (NMR). Samples were also evaluated by fluorometry and X‐ray diffraction to determine the extent of browning reaction and degree of molecular ordering, respectively. While elastic modulus increased appreciably during storage, firming was progressively reduced by entrained meat content and also by plasticizers, especially glycerol; plasticized and meat‐containing samples had correspondingly lower tan δ peak temperatures as measured by DMS. Textural results were also in keeping with fluidity and local viscosity as assessed by ESR measurements. NMR T1 relaxation values, reflecting moisture mobility, increased during storage. Diffraction spectra were consistent with published observations of hydrated starch, suggesting that water may have been released due to increased association of proteinaceous constituents. Fluorescence measurements confirmed moderate Maillard browning in all samples and significant chlorogenic browning in glucose‐containing samples, although these effects were unrelated to degree of firming. It was concluded that textural stability was optimized by interruption of the matrix by dispersed meat or by plasticization by low molecular weight constituents. 相似文献
87.
OBJECTIVE: Renewed focus on public health has brought about considerable interest in workforce development among public health nutrition professionals in Canada. The present article describes a situational assessment of public health nutrition practice in Canada that will be used to guide future workforce development efforts. METHODS: A situational assessment is a planning approach that considers strengths and opportunities as well as needs and challenges, and emphasizes stakeholder participation. This situational assessment consisted of four components: a systematic review of literature on public health nutrition workforce issues; key informant interviews; a PEEST (political, economic, environmental, social, technological) factor analysis; and a consensus meeting. FINDINGS:Information gathered from these sources identified key nutrition and health concerns of the population; the need to define public health nutrition practice, roles and functions; demand for increased training, education and leadership opportunities; inconsistent qualification requirements across the country; and the desire for a common vision among practitioners. CONCLUSIONS: Findings of the situational assessment were used to create a three-year public health nutrition workforce development strategy. Specific objectives of the strategy are to define public health nutrition practice in Canada, develop competencies, collaborate with other disciplines, and begin to establish a new professional group or leadership structure to promote and enhance public health nutrition practice. The process of conducting the situational assessment not only provided valuable information for planning purposes, but also served as an effective mechanism for engaging stakeholders and building consensus. 相似文献
88.
Summary Four varieties of lupins were sown at three planting dates and the level of Phomopsis leptostromiformis measured on the mature stems. When averaged over planting dates the varieties did not differ in resistance to this disease, however there were highly significant interactions between varieties and planting dates for level of disease. The implications of this result for resistance breeding to Phomopsis leptostromiformis are discussed. 相似文献
89.
Andon Vassilev Araceli Perez-Sanz Ann Cuypers Jaco Vangronsveld 《Journal of plant nutrition》2013,36(9):1471-1482
Woody cuttings from two Salix genotypes (genotype I—clone LUC-31, Salix alba and genotype II- clone STOTT, Salix viminalis) were grown hydroponically for 14 days at increasing concentrations of Zn: control, 50, 100 or 150 μ M Zn. Genotype tolerance to excess zinc (Zn) was evaluated using a root elongation test. The changes in growth, Zn, iron (Fe), copper (Cu) and manganese (Mn) concentrations as well as photosynthetic performance were used as additional evaluation criteria. Photosynthetic pigments concentrations in Zn-exposed cuttings of genotype II decreased as compared with genotype I, which corresponded well with the higher leaf Zn accumulation, decreased Fe concentrations as well as lowered photosynthetic rate. Based on the indicators used, genotype I (Salix alba) was classified as more tolerant to excess Zn than genotype II (Salix viminalis). 相似文献
90.
Influence of drought and salt stress on different morphological and physiological growth parameters in Capsicum annuum inoculated with our isolates was estimated during the present study. Bulkhorderia cepacia was reported to possess the maximal, whereas Citrobacter feurendii the least plant growth promoting efficacy under salt and drought stress. ACC Deaminase activity of purified B. cepacia, C. feurendii and Serratia marcescens was 12.8 ± 0.44, 12.3 ± 0.56 and 11.7 ± 0.53 μM αKB mg?1 min?1 respectively. Under drought stress, B. cepacia showed maximum tolerance as it produced 4.893 ± 0.06 mg/mg protein of exopolysaccharide followed by C. feurendii and S. marcescens that produced 4.23 ± 0.03 and 3.46 ± 0.05 mg/mg protein, respectively. Chlorophyll “a” concentration was recorded 5.7 gm L?1 in B. cepacia inoculated plant (without stress) and was sustained till 2.9 gm L?1 even under the highest tested drought period. Chlorophyll “a” concentration in the B. cepacia inoculated plant under the highest tested NaCl concentration was 3.2 gm L?1. Thus, bacterial inoculation mitigates the effects of salinity by the proliferation of root system, increasing plant biomass proving to be potential bioinoculum for alleviating abiotic stress. 相似文献