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51.
Aquaculture International - There is developing importance in the biomedical use of seaweeds such as brown algae, mostly due to their contents of bioactive substances. In the present study,...  相似文献   
52.
The present investigation was carried out to evaluate the detoxification potential of Pseudomonas fluorescens SM1 strain immobilized in calcium alginate beads for some major toxicants of Indian water bodies. The toxicants selected in this study were benzene hexachloride, mancozeb, 2,4-dichloro-phenoxyacetic acid (pesticides); phenol, catechol, cresol (phenolics); and Cd++, Cr(VI), Cu++ and Ni++ (heavy metals), which were taken as mixtures up to a concentration of roughly twice that usually found in highly polluted sites. Allium cepa phytotoxicity test, Ames fluctuation test and plasmid nicking assay were employed to estimate the phytotoxicity and genotoxicity of the model water containing the test toxicants under different combinations before and after exposure to our bioremediation-cum-detoxification system. The IC50 of the model water containing all the test toxicants, treated with the immobilized SM1 cells, was recorded to be 0.7× compared to 0.06× for the same but untreated water sample, enhancing the IC50 value by 12-fold. The IC25 of the test heavy metal mixture only could enhance from 0.07 to 1.30× (18-fold). The IC25 of the test pesticide mixture alone was increased from 0.07 to 1.71× (24-fold). The IC25 values for the mixture of test phenolics were 0.07× and 2.18× under the pre- and post-treatment conditions, respectively, exhibiting a 31-fold increase. A mutational induction (Mi) corresponding to the 0.5 value in the Ames fluctuation test was used to evaluate the mutagenicity of the test model water containing all the toxicants before and after exposure to the immobilized SM1 cell system. The Mi (0.5) value with the TA98 tester strain was estimated to be 0.08× for the untreated and 0.6× for the treated model water, whereas the same index was calculated to be 0.48× and 1.8×, respectively, for the TA100 strain. A remarkable improvement in the quality of the test water as a result of exposure to this bioremediating system was observed in terms of the absence of the linear form of the plasmid contrary to the visible linearization with the untreated model water. In view of the above findings, it is quite clear that the test of P. fluorescens SM1 strain immobilized in the calcium alginate beads could be used as an efficient system of bioremediation and for water decontamination strategies owing to its remarkable detoxification potential.  相似文献   
53.
ABSTRACT

This study was conducted in a greenhouse to evaluate the root and shoot response of canola (Brassica napus L.) to salt-stress conditions and the remobilization, deposition, and input rate of sodium (Na), potassium (K), and magnesium (Mg) at different salinity levels using two canola cultivars. A salt-tolerant (‘Kristina’) cultivar and a salt-sensitive (‘Hyola 308’) cultivar were grown in nutrient solutions with 0, 50, 100, 150, and 200 mol m?3 NaCl for 7 d. The plants were harvested after 6, 12, 18, and 24 h and 3 and 7 d after salt treatment. The results indicated that increasing salinity significantly decreased shoot and root weights 7 d after treatment. Also, K content and K-Na selectivity decreased in both cultivars, but the changes in ‘Hyola 308’ were greater than in ‘Kristina.’ Electrolyte leakage was increased significantly by salinity, and cell-membrane stability of ‘Hyola 308’ was damaged more than that of ‘Kristina’. Sodium import, transport, and deposition was increased by salinity concentration but remobilization was decreased. The K and Mg import, deposition, and remobilization were also decreased. From this experiment we can conclude that greater K and Mg remobilization in ‘Kristina’ could be a mechanism of salt tolerance in canola.  相似文献   
54.
Parts of paddy fields in Mazandaran Province, northern Iran, are confronted with soil and water salinity. To screen proper rice cultivars, an experiment was performed with eight modified rice cultivars under four levels of irrigation water salinity (1, 2, 4 and 6 dS m?1) with three replications, in Amol, northern Iran. The objective of the present study was the evaluation of eight screening indices for identifying salinity tolerance of these cultivars, so that suitable cultivars can be recommended for the cultivation with saline irrigation water in paddy fields. To evaluate the resistance of these cultivars to salinity stress, different indices were calculated. The results showed that Khazar cultivar was the most salt-sensitive cultivar in all salinity levels. In the irrigation salinity levels of 2 and 4 dS m?1 Neda cultivar and in the level of 6 dS m?1 Dasht cultivar were the most salt-resistant cultivars. In the two irrigation salinity levels of 4 and 6 dS m?1, the mean productivity index was the most effective in the screening of salt-resistant cultivars. Harmonic mean, geometric mean productivity, stress tolerance index and mean productivity indices were found to be the best indices in screening resistant cultivars.  相似文献   
55.
Persian shallot (Allium altissimum Regel.) was grown under fully irrigated conditions in a 2-year-field experiment (2010–2012) in the northeast of Iran to study and determine (i) radiation and nitrogen-use efficiency, (ii) growth analysis, (iii) carbon partitioning, and (iv) biomass production under different rates of nitrogen and cultivated bulb weights. The field experiment was performed as a randomized complete block design with a factorial arrangement of four nitrogen levels (control (100), 200, 250, and 300 kg ha?1) and two levels of cultivated bulb weight (10–20 and 20–30 g) with three replications in both years of the experiment. Our results showed that increasing the nitrogen rate and bulb weight significantly enhanced Persian shallot production. Radiation-use efficiency (1.06 to 1.27 g MJ?1), maximum crop growth rate (8.3 to 11.2 g m?2 d?1), and maximum leaf area index (1.3 to 2.6) showed a positive correlation with nitrogen rate and bulb weight. Nevertheless, nitrogen-use efficiency (0.87 to 2.38 g bulb per g nitrogen) indicated a negative relationship with applied nitrogen rate. Moreover, increasing the nitrogen application rate increased the carbon allocation to above-ground organs. On the other hand, nitrogen limited conditions increased the carbon allocation to underground organs and carbon remobilization from stem and leaves to bulbs during the late growth season. Increasing the nitrogen application rate and bulb weight may be appropriate practices for enhancing Persian shallot production; however, evaluation of the impact of nitrogen on the quality of bulbs needs to be investigated.  相似文献   
56.
Species of barberry (Berberis vulgaris L. var. asperma) is cultivated in arid and semi arid areas of Iran (South Khorasan province). It is widely used as a food additive. Fruits of this species are seedless, while wild type barberries produce seeds in the same area. In this study, we investigated the mechanism of seedlessness in seedless barberry by pollen viability test, field pollination experiments and microscopic observation of pollen tube growth in pistil and ovule development. For comparison, we also examined ovule development in wild type barberry (B. crataegina DC). In seedless barberry pollen germination was about 54%. Seedless barberry produced 20% seeded fruits when pollinated with pollen of wild type barberry. There was a sharp decrease in fruit set in emasculated unpollinated flowers of seedless barberry. In seedless barberry, a large number of pollen grains (about 370) were observed on stigma of each flower at 12 h after balloon stage (ABS). Most of them germinated and penetrated intracellular area of stigma surface, but no pollen tube reached ovary. In seedless barberry, many ovules did not have any embryo sac or had a very small incomplete embryo sac. In addition, unfused polar nuclei were clearly recognized in some cases at 14 days after full bloom (AFB). However, in wild type, double fertilization was accompanied by disappearance of polar nuclei. In seeded barberry, the cellularized endosperm became apparent at seven days AFB. At 21 days AFB, all ovules of seedless barberry were degenerated, while at the same time in wild type, one or two ovules of each flower were normal and were developing into complete seeds. Results showed that self-incompatibility has a main role in seedlessness of seedless barberry. However, the high frequency of abnormal ovules and single fertilization can be considered as two other reasons of seedlessness. Due to our results, fruits of seedless barberry were set by stimulative parthenocarpy.  相似文献   
57.
Pistachio trees exhibit some physiological disorders such as abscission of inflorescence buds, fruit abscission, the production of blank, non-split, early-split and deformed nuts. Since the occurrence of these disorders is closely related to the yield, the effect of free polyamine treatments on these disorders and the yield was investigated in two consecutive years (“on” and “off” years). Free polyamine treatments were applied one week before and also two weeks after full bloom. Results showed that Spermine (Spm), unlike Putrescine (Put), decreased the physiological disorders of pistachio and also increased the yield. Free polyamine treatments did not affect the percentage of early-split nuts. Spermidine (Spd) decreased the percentage of both fruit abscission and deformed nuts but did not affect the yield. In both the “on” and “off” years the effect of Spm and Spd was greatly dependent on both the time of application and the concentrations used. Results of free polyamine analysis showed that exogenous application of these compounds, especially two weeks after full bloom, increased the free polyamine contents of shoots in both “on” and “off” years confirming the absorption of free polyamines via spray application in pistachio crop. Exogenous application of Spm two weeks after full bloom decreased the abscission of inflorescence buds in “on” year supporting the idea that free polyamines could trigger the abscission process of inflorescence buds. Since Spm decreased the percentage of blank, non-split and deformed nuts, it seems that Spm dominantly plays a key role in the growth and development of pistachio nuts.  相似文献   
58.
Utilization of agricultural wastes in animal nutrition is a matter of great concern. Dried citrus pulp (DCP) is a potential source of some valuable nutrients for animal and poultry. In an experiment with completely randomized design, the effect of different levels (0%, 4%, 8%, 12%, and 16%) of DCP was evaluated on performance, egg quality, and blood parameters of laying hens from 25 to 37 weeks of age. The birds were randomly allocated to five groups with six replicates and three birds in each replicate. The results showed that with increasing the level of DCP up to 12%, there were no significant differences among treatments for feed intake, egg production, egg mass, feed conversion ratio, final body weight, yolk index, and yolk color. There were no significant differences between treatments in shell thickness, eggshell index, egg score, and Haugh unit. Utilization of DCP up to 16% significantly increased serum glucose and high-density lipoprotein and reduced cholesterol, low-density lipoprotein, and triglycerides (P < 0.05). Results of the present study indicated that use of 12% DCP in laying hen diets had no adverse effect on performance and egg quality of laying hens in early phase of production.  相似文献   
59.
One of the major changes that have occurred over the past few years is the re-examination of conventional methods and the global demand for innovative low cost bioassay tests for assessing water quality, toxicity evaluation and bioremediation. In the present study acute toxicity, physiological and cytotoxic impact of carbofuran to a commonly occurring fresh water ciliate was measured. Intrinsic cytotoxicity was evident on macro nuclear apparatus that exhibited deformities such as fragmentation, deep incision, vacuolization and degenerative macronucleus. Depletion in the food vacuole formation of Paramecia was evident. Changes in the pulsatory vacuole activity of Paramecium caudatum, highlighted dose dependent response by the test compound. The simplicity of handling this ciliate makes unicellular eukaryote, an alternative organism for the toxicity assessment of pollutants. The tests carried in this study are simple and fast, a bioassay that gives overall information about the physiological and cytotoxic effects of carbofuran to P. caudatum. Such bioassay tests using ciliates are more suitable for risk assessment of water quality, early detection of water pollution and possible role of ciliates as bioindicators and strategic tools in the bioremediation of water bodies.  相似文献   
60.
The present study evaluated various sodium and potassium concentrations in hatchery water to determine which proportions would be optimal for Macrobrachium rosenbergii larviculture. Using a closed RAS system (60‐L), experiments were conducted in two stages. In the first stage, larval quality parameters were compared among triplicate treatments of sodium (2000, 3000, 4000 and 5000 mg L?1) and potassium (100, 150, 200 and 250 mg L?1). During the second stage, these same parameters were compared from interactions of the two best concentrations determined in the first stage. Initial larval density was fixed at 100 larvae L?1 and larval quality parameters such as larval stage index (LSI), larval condition index (LCI), larvae dry weight, survival (%), LC50‐24 h for formalin stress and time of the first postlarvae (PL) appearance were measured. Results showed that during the early larval period time LSI, LCI and survival parameters were affected only by potassium and the interaction with sodium was not significant. At a later period of the larval development, interactions between both sodium and potassium were measurable for LSI (< 0.05) while the interactions on LCI and survival were not significant. Measurable differences among the combined treatments 4000 mg L?1 sodium and 150 mg L?1 potassium resulted in the best performance for M. rosenbergii larviculture. This concentration also provided the highest final survival to PL metamorphosis (40.6 ± 2.5%) which was at least 10% higher than the other treatments.  相似文献   
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