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1.
Lycopersicon esculentum cultivar Micro-Tom is a miniature tomato with many advantages for studies of the molecular biology and physiology of plants. To evaluate the suitability of Micro-Tom as a host plant for the study of pathogenesis, Micro-Tom plants were inoculated with 16 well-known fungal, bacterial, and viral pathogens of tomato. Athelia rolfsii, Botryotinia fuckeliana, Oidium sp., Phytophthora infestans, and Sclerotinia sclerotiorum caused typical symptoms and sporulated abundantly on Micro-Tom. Micro-Tom was resistant to Alternaria alternata, Corynespora cassiicola, and Fusarium oxysporum. When Micro-Tom was inoculated with 17 isolates of Ralstonia solanacearum, many isolates induced wilt symptoms. Agrobacterium tumefaciens also was pathogenic, causing crown galls on stem tissue after needle prick inoculation. In Micro-Tom sprayed with Pseudomonas syringae pv. tomato, P. s. pv. tabaci, or P. s. pv. glycinea, bacterial populations did not increase, and yellow lesions appeared only on leaves sprayed with P. s. pv. tomato. Tomato mosaic virus, Tomato aspermy virus, and Cucumber mosaic virus systemically infected Micro-Tom, which developed symptoms characteristic of other cultivars of tomato after infection with the respective virus. These results indicated that Micro-Tom was generally susceptible to most of the important tomato pathogens and developed typical symptoms, whereas certain pathogens were restricted by either hypersensitive resistance or nonhost resistance on Micro-Tom. Therefore, an assortment of Micro-Tom–pathogen systems should provide excellent models for studying the mechanism of susceptible and resistant interactions between plants and pathogens.  相似文献   
2.
Aciculosporium take (Ascomycota; Clavicipitaceae) is a causal agent of witches' broom of bamboo plants. The symptoms of this disease are believed to be induced by plant hormones, particularly auxins. Indole-3-acetic acid (IAA) was identified in cultures of this fungus in an l-tryptophan-supplemented liquid medium. IAA production was confirmed on 30 isolates of A. take from various hosts and locations at levels up to 1 mg/l. The biosynthetic pathway of IAA in A. take culture was examined by analyzing intermediate products and by feeding experiments. The results showed that the indole-3-pyruvic acid pathway (l-tryptophan → indole-3-pyruvic acid → indole acetaldehyde → IAA) was the dominant pathway in A. take. Received: June 3, 2002 / Accepted: July 25, 2002  相似文献   
3.
Cu、Cd、Pb、Zn、As复合污染对灯心草的生理毒性效应   总被引:3,自引:0,他引:3  
孙健  铁柏清  钱湛  杨佘维  毛晓茜  赵婷  罗荣  青山勋 《土壤》2007,39(2):279-285
通过盆栽试验,以现行土壤环境质量标准为浓度设置依据并结合实际污染土壤研究了不同处理水平的Cu、Cd、Pb、Zn、As5种重金属复合污染对灯心草生长、叶绿素含量及保护酶系统的影响。实验结果表明:5种重金属复合污染对灯心草地上部生长有一定程度的抑制作用,在土壤环境质量二级标准上限值处灯心草地上部生物量减产9.15%,<10%,但地下部生物量减产趋势不明显。复合重金属污染抑制灯心草的光合作用使叶绿素含量减少、叶绿素a/b值降低。在接近土壤环境质量标准低浓度设计范围内,灯心草3种保护酶有逐渐被激活的趋势,表现出一定的协调性共同抵制重金属的毒害。但在高浓度处理水平下,酶活性遭到抑制。生长在矿毒水和铅锌尾矿污染土壤中的灯心草地上部生物量分别下降28.23%和37.1%,但POD、SOD和CAT3种酶活性均高于对照。通过应用综合生态环境效益法,以灯心草为指示植物可以将土壤环境质量二级标准上限值设定为土壤中5种重金属的临界毒性效应值。  相似文献   
4.
Three optic nerves (L1, R2, R3) 12-18 mm behind the eyeball of the horse (Thoroughbred) were investigated quantitatively under light and electron microscopes. Thin sections at the thickness of 0.35 microm were cut, stained by toluidine blue and observed under the light microscope. The areas of the optic nerve and the axon bundles were 20.03 +/- 1.04 and 16.59 +/- 0.79 mm2 (mean +/- SD, n=3), respectively. The axon numbers for optic nerve L1, R2 and R3, estimated from light micrographs, were about 481 x 10(3), 543 x 10(3), and 494 x 10(3), respectively. Axons of optic nerve L1 were also counted from electron micrographs and the total number of 488 x 10(3) was received. Furthemore, axon diameters of optic nerve L1 were also measured from electron micrographs. The diameter of a circle with the same peripheral length as an axon, was regarded as its diameter. The medullary sheath of the axon was not included during measuring. Altogether 5,744 axons were measured and axon diameters were in a range of 0.23-12.69 microm, with a mean of 2.56 +/- 1.45 microm (mean +/- SD). A regional difference of axonal diameters was found across the optic nerve: the mean diameter of axons in the centrodorsal region (2.28 microm) was the smallest, and had significant difference with those in several peripheral regions (P<0.05).  相似文献   
5.
In order to estimate the influence of the Extension (E) locus in cattle coat color, the melanocortin‐1 receptor (MC1R) gene in Japanese Black, Japanese Brown and Korean (Hanwoo) cattle were sequenced. The sequences of the coding region revealed three alleles (ED, E+ and e), which were previously reported. Polymerase chain reaction‐restriction fragment length polymorphism was performed to investigate the gene frequencies of the three breeds. Japanese Black was almost composed of ED and E+ individuals, ED = 0.481 and E+ = 0.514, and no homozygous e/e, therefore that is consistent with the hypothesis that ED and E+ induce black pigment synthesis. Allele frequencies between Japanese Brown and Hanwoo were obviously different; however, recessive red e allele frequency was 0.038 for Japanese Brown and 0.948 for Hanwoo, even though both breeds have quite similar coat colors (ranging from yellowish brown to dark brown including a red coat color). This result suggested that other genes are also associated with a coat color of red and brown in cattle.  相似文献   
6.
7.
Antifeedant activity of some flavonoids and their related compounds against the subterranean termiteCoptotermes formosanus Shiraki was examined with nochoice tests and two-choice tests. The activities of these compounds were evaluated in relation to their chemical structures. All flavonoids tested showed antifeedant activity, whereas catechinic acid, possessing no A-ring or pyran ring in the molecule, showed feeding-preference activity. For the structure-activity relations, it was found that compounds containing two hydroxyl groups at C-5 and C-7 in A-rings showed high antifeedant activity. Furthermore, the presence of a carbonyl group at C-4 in the pyran rings of the compounds was necessary for the occurrence of high activity. 3-Hydroxyflavones and 3-hydroxyflavanones with 3,4-dihydroxylated B-rings exhibited higher activity than those with 4-hydroxylated B-rings.Part of this paper was presented at the 49th annual meeting of the Japan Wood Research Society, Tokyo, April 1999  相似文献   
8.
A carbonaceous sorbent was prepared from the wood of Japanese larch (Larix leptolepis) by dehydration with concentrated sulfuric acid in a 69% yield. The abilities of the sorbent to remove Cr(VI) from aqueous solutions were investigated. Research parameters included the initial solution pH, temperature, and initial concentration of Cr(VI) in solution. The removal of Cr(VI) was highly solution pH dependent and was mainly governed by physicochemical sorption under weak acidic conditions. The equilibrium data fit well in the Langmuir isotherm model. The Langmuir constants were calculated at different temperatures, and the sorption capacity increased with rising temperature, indicating the endothermic nature of the Cr(VI) sorption onto the sorbent. The desorption experiments suggest that the Cr(VI) sorption is generally irreversible, owing to strong interaction of HCrO 4 with the active sites of the sorbent.  相似文献   
9.
The bark of Japanese cedar (Cryptomeria japonica D. Don) was heated in an N2 atmosphere at 300–900C for 3h to investigate the surface properties of the pyrolyzed residuces and their ability to remove trichloroethylene (TCE) from aqueous solutions. The specific surface areas (S N) and total pore volumes (V N) of the pyrolyzed barks steadily increased with rising pyrolysis temperature; no significant differences in the average pore diameters (D N) were observed at higher temperatures (600–900C). The adsorption capacities of the pyrolyzed residues for TCE were determined under batch mode conditions using an aqueous solution containing 500g TCE dm–3. The adsorption data were well fitted to the Freundlich equation. The adsorption capacity of the bark pyrolyzed at 900C was about five times larger than that of commercial activated carbon.This study was presented at the 10th International Symposium on Wood and Pulping Chemistry, Yokohama, June 1999  相似文献   
10.
We investigated the effects of high-temperature drying schedules (120°–130°C) on decay and termite feeding of Japanese larch timbers. Thermogravimetric analysis was conducted to investigate changes of the wood components. Decay and termite feeding tests showed that specimens dried under high-temperature schedules were susceptible against a decaying fungus Fomitopsis palustris and attacks from termites Coptotermes formosanus and Reticulitermes speratus. These drying schedules changed chemical components, which were suggested by the thermal analytical result compared to the control sample. The results of this study indicated that the acceleration of termite feeding takes place even under temperatures that are comparatively lower than that used in our previous research in which 170°C steaming treatment was applied to Japanese larch wood. Decay durability against a brown rot fungus also decreased, possibly from production of low molecular weight fragments when hemicellulose decreased during the high-temperature drying processes.  相似文献   
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