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51.
This study aimed to investigate the effects of nitrogen (N) fertilizer application and harvesting stage on the contents of chlorophyll, phytol and carotenoids (β‐carotene and lutein) in Italian ryegrass herbage before and after ensiling, and the extent of phytol preservation after ensiling. Three rates of N fertilizer (0, 60 and 120 kg N/ha) were applied by top‐dressing as an additional fertilizer. The herbage harvested at booting stage (27 weeks of age) or heading stage (29 weeks of age) were wilted for 1 day, then ensiled for 60 days using a small‐scale pouch system. In the pre‐ensiled herbages, increasing N fertilizer application increased the contents of crude protein and photosynthetic pigments, and these contents were also higher at the booting stage compared with the heading stage. In the silage, increasing N fertilizer application also increased the contents of crude protein, the photosynthetic pigments and their derivatives (pheophytin and pheophorbide), while harvesting stage did not affect the contents of β‐carotene, chlorophylls or pheophorbide. Nitrogen fertilizer application and early harvesting of herbage increased lutein and phytol contents in Italian ryegrass silage. Lutein and phytol in Italian ryegrass herbage are indicated to be well preserved during ensiling.  相似文献   
52.
Six wheat genotypes with wide genetic variability for resistance to bacterial leaf streak were crossed in diallel fashion to determine the inheritance of resistance to this disease. Parental genotypes and their F1 hybrids were inoculated at the second leaf stage with an Iranian isolate of Xanthomonas campestris pv. cerealis . Two experiments were undertaken in a controlled environment chamber. Results showed that the genotypes IBPT66, IBPT84 and IBPT34 had a high level of partial resistance to the disease. General and specific combining abilities presented several significant positive or negative values, showing the importance of both additive and dominant genetic control for partial resistance to this bacterial disease. The resistant line IBPT66 could be a good donor of partial resistance to bacterial leaf streak in wheat.  相似文献   
53.
S.O. EL  HIWERIS 《Weed Research》1987,27(5):305-311
Ten Sorghum vulgare (Pers.) cultivars varying in tolerance to Striga hermonthica (Del.) Benth. parasitism were grown with or without Striga infection. Endodermal thickening, pericycle lignification and silica crystal deposition were studied microscopically and measured for infected and non-infected sorghum cultivars. Although differences in the root character measurements were statistically significant they were not closely related to the response of the plant to infection. Low stimulant producing cultivars showed low or medium root cell thickening. The cv. Framida had both low stimulant production and high root cell thickening and was the best of the tolerant cultivars. High stimulant producing, tolerant cultivars generally showed heavy or intermediate cell thickening. The high stimulant producing, susceptible cultivar Debaikri also showed intermediate root cell thickening.‘Antibiosis', measured by the content of phenolic compounds in the plant, was then studied. Varietal differences in quality and quantity of phenolic substances in the roots and shoots of sorghum cultivars infected or non-infected with Striga were observed. Infection increased total phenolic contents in both shoot and root extracts. Differences in the total phenolic content in the shoot of non-infected cultivars did not reflect tolerance to Striga infection. The total phenolic acid content of the root extracts was closely related to the response of the host plant to Striga infection, tolerant cultivars having greater total phenolic acid content than susceptible ones.  相似文献   
54.
EL ATTA  H. ALI; HAYES  A. J. 《Forestry》1987,60(1):101-111
In two stands of Norway spruce (Picea abies (L.) Karst.), plantedin 1952 and 1929 in Yair Hill Forest and Glentress Forest, BordersRegion, two per cent of the trees examined in 1983 had extractiondamage on stems and superficial roots. Extraction wounds were4 and 8 years old respectively and ranged in size from 52 to1099 cm2. Infection frequency of the damaged trees was 47 percent and 54 per cent respectively. Stereum sanguinolentum wasthe most common fungus isolated, accompanied by Trichodermaviride Fr; Chaetomium cochlioides Palliser and Heterobasidionannosum (Fr.) Bref. The frequency of isolation of S. sanguinolentumincreased progressively in samples taken from the outside ofstems inwards, whereas the other microorganisms present showedthe opposite pattern. In four trees, T. viride overgrew S. sanguinolentumin the the decay columns. Positive correlations were demonstratedbetween surface area of wounds and vertical extension of decay,tree volume and decay volume, and diameter of stem at breastheight (DBH) and decay volume; whereas a negative correlationoccurred between number of growth rings per 5 cm (measured inwardsfrom the outside of the bole) and radial penetration of decay.The results confirm the importance of S. sanguinolentum as awound pathogen.  相似文献   
55.
This study aimed to evaluate the effectiveness of hormonal treatments on ovarian activity and reproductive performance in Barki and Rahmani ewes during non‐breeding season. Forty‐eight multiparous ewes, 24 Barki and 24 Rahmani ewes were divided into two groups, 12 lactating and 12 dry ewes for each breed. Controlled internal drug release (CIDR) device was inserted in all ewes for 14 days in conjunction with intramuscular 500 IU equine chronic gonadotrophin (eCG) at day of CIDR removal. Data were analysed using PROC MIXED of SAS for repeated measures. Breed, physiological status and days were used as fixed effects and individual ewes as random effects. Barki ewes recorded higher (p < .05) total number of follicles, number of large follicles, serum estradiol concentration and estradiol: progesterone (E2:P4) ratio compared to Rahmani ewes. Lactating ewes recorded higher (p < .05) number of small follicles and lower concentration of total antioxidant capacity (TAC) compared to dry ewes. Number and diameter of large follicles recorded the highest (p < .05) values accompanied with disappearance of corpora lutea at day of mating. Serum progesterone concentration recorded lower (p < .05) value at day of mating and the highest (< .05) value at day 35 after mating. CIDR‐eCG protocol induced 100% oestrous behaviour in both breeds, but Rahmani ewes recorded longer (< .05) oestrous duration compared to Barki. Conception failure was higher (< .05) in Barki compared to Rahmani ewes. In conclusion, CIDR‐eCG protocol was more potent in improving ovarian activity in Barki compared to Rahmani ewes, but this protocol seems to induce hormonal imbalance in Barki ewes that resulted in increasing conception failure compared to Rahmani ewes.  相似文献   
56.
The main objectives of this study was to evaluate the effect of partial and total replacement of fishmeal protein by okara meal (OM) protein in practical diets on growth performance, feed utilization and body composition of Nile tilapia (Oreochromis niloticus L.) mono‐sex males. Fish of an average initial weight of 2.67 ± 0.01 g were stocked in 15 glass aquariums (80 L each) at a rate of 15 fish per aquarium. Fishmeal protein (18% of the diet) was used as the sole source of animal protein in the control diet. Percent replacement of fish meal (FM) by OM on the basis of crude protein was as follows: 0% (control diet A), 25% (diet B), 50% (diet C), 75% (diet D) and 100% (diet E). Diets were fed to fish at a rate of 5%, and then gradually reduced to 4% of the total fish biomass daily, for a period of 12 weeks. The results revealed that the fish fed diets A (100% FM control), B (25% OM), C (50% OM) and D (75% OM) had significantly the best average body weight, weight gain g, specific growth rate (SGR % day?1), weight gain % and feed intake g fish?1 compared with diet E (100% OM) which had the lowest values. There were no significant differences (P > 0.05) among all experimental diets and control in terms of feed conversion ratio (FCR), protein efficiency ratio (PER) and survival rate %. Whole body protein contents for fish fed diets B, C and D were superior to the control diet. Incorporation of OM in the diets increased significantly whole body fat content. Incorporation of OM in the diets significantly increased apparent digestibility coefficient of crude protein crude fat and energy. Therefore, these findings suggest that up to 75% of FM protein can be replaced by OM protein in Nile tilapia, mono‐sex male diets.  相似文献   
57.
除草剂对土壤微生物生物量和氮矿化的影响   总被引:5,自引:0,他引:5  
除草剂对土壤微生物生物量和氮矿化有不同的影响效应,这与除草剂类型、除草剂浓度、土壤类型以及包括温度、水分、培养时间等实验条件有关,这些影响效应在土壤肥力和环境保护上的重要性也进行了讨论。  相似文献   
58.
The current experiment was carried out to evaluate the effect of different dietary chromium supplementation sources, chromium oxide (Cr2O3), chromium methionine (Cr‐Met), or chromium yeast (Cr‐yeast), at different levels each (500 or 1,000 ppb) on growth performance, physiological traits, and carcass characteristics of broiler chicks. A total of 490 seven‐day‐old Arbor Acres chicks were randomly distributed into 7 experimental groups each in 10 replicates of 7 birds each. The groups were control, 500 ppb Cr2O3, 1,000 ppb Cr2O3, 500 ppb Cr‐Met, 1,000 ppb Cr‐Met, 500 ppb Cr‐yeast, and 1,000 ppb Cr‐yeast. The results showed significant superiority of the organic chromium sources (Cr‐Met or Cr‐yeast) concerning body weight and weight gain, the group supplemented with 1,000 ppb Cr‐yeast consumed the lowest feed (3,185 g) and had the best feed conversion ratio (1.60) compared to the control (1.73). The chromium treatments recorded significantly better protein and lipid profile, antioxidant status, and immunological parameters than the control group. Similarly, dietary chromium supplementation increased carcass yield and decreased intestinal pathogenic bacteria. In conclusion, supplementing broiler diets with organic chromium sources at 1,000 ppb promotes growth performance, physiological traits, and carcass characteristics; such chromium treatments enhanced the antioxidant status and immunity levels of broilers.  相似文献   
59.
Calving ease (CE) is a trait of economic importance that affects animal welfare and farm profitability. The objective of present study was to investigate genetic and environmental factors affecting CE among Primiparous (PP) and multiparous (MP) buffaloes. A total of 9,627 records from 1999 MP and 2,110 PP recorded during the period from 1988 to 2018 were considered. Herd, season of calving, year of calving, birth weight, parity order and gestation length significantly affected CE rate, while age at first calving and sex of calf had no significant effects. Direct and maternal heritabilities of CE in PP and MP were 0.06 and 0.01, respectively. The low heritability of CE indicated that direct selection may not be an effective method to improve CE trait in Egyptian buffalo.  相似文献   
60.
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