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The papaya mealybug, Paracoccus marginatus Williams and Granara de Willing (Coccomorpha: Pseudococcidae), is a polyphagous pest that damages many tropical crops. It is native to Central America and spread to the Caribbean region and South America in the 1900s. Since then, it has accidentally been introduced to several islands in the Pacific region and some countries in Africa and Asia. The first record of this mealybug in Polynesia was in Hawaii, in 2004. This paper presents the first report of this pest in Tahiti (French Polynesia), where it was found in March 2017 on papaya (Carica papaya) and frangipani trees (Plumeria spp.). Its presence, which is mainly in the inhabited part of the island of Tahiti, suggests the recent introduction of the pest in French Polynesia. Several coccinellid predators have been found feeding on the mealybug in Tahiti: Cryptolaemus montrouzieri, Hyperaspis pantherina and Scymnus spp. None of its parasitoids have been found yet. 相似文献
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采用聚丙烯酰胺凝胶电泳的方法,对花生属植物10个栽培种和10个野生种的酯酶同工酶谱带进行测定分析。根据酶谱的差异,栽培种花生与花生区组野生种的平均相似值为12.93%,与其他区组相比其相似值高。表明两者间亲缘关系较近,从生化测定证实了花生区组的野生种是栽培种的近缘祖先的推断。另外,结果表明不同类型的栽培种与花生区组的各个野生种的亲缘关系也存在差异,其中以珍珠豆型品种与A.durenesis的关系最近。 相似文献
125.
H. Zhang S. N. Tan W. S. Wong C. Y. L. Ng C. H. Teo L. Ge X. Chen J. W. H. Yong 《Biology and Fertility of Soils》2014,50(2):401-403
Through their decomposing activities, earthworms produce rich organic fertilizers called vermicomposts containing mineral nutrients and anecdotal evidence of biologically active phytohormones. Aqueous extracts of vermicomposts, namely vermicompost tea (VT), have positive effects on plant growth. It has been postulated that trace amounts of phytohormones in vermicomposts or its VT are beneficial for plant growth and development. We therefore screened for the different classes of phytohormones (auxins, cytokinins, abscisic acid, and gibberellin) in VT using liquid chromatography–tandem mass spectrometry (LC–MS/MS) after solid-phase extraction. VT was produced by earthworms being fed with a mixture of water hyacinth (Eichhornia crassipes) and chicken manure at a ratio of 4:1 (w/w). This investigation is the first mass spectrometric evidence for the presence of cytokinins in VT: namely trans-Zeatin (tZ), N6-Isopentenyladenine (iP) and N6-Isopentenyladenosine (iPR), which were present at 0.06, 3.33, and 0.02 nmol L–1, respectively. The successful detection and quantitation of cytokinins in VT provided direct evidence to explain the growth efficacy of applying VT in order to enhance plant growth and development. We postulated that they were microbially synthesized due to the abundance of microbial communities in the vermicompost. 相似文献
126.
Joshua H. Wong Tsang Lau Nick Cai Jaswinder Singh Jeffrey F. Pedersen William H. Vensel William J. Hurkman Jeff D. Wilson Peggy G. Lemaux Bob B. Buchanan 《Journal of Cereal Science》2009
Although a principal source of energy and protein for millions of the world's poorest people, the nutritional value of sorghum (Sorghum bicolor L. Moench) is diminished because of low digestibility of grain protein and starch. To address this problem, we analyzed the properties of two sorghum lines that have a common pedigree but differ in digestibility. Consistent with results based on a ruminal fluid assay, the protein and starch of one line (KS48) was more thoroughly digested than that of the other (KS51) using in vitro assays based on pepsin and α-amylase. The indigestibility of KS51 relative to KS48 was shown to be due to (i) a greater abundance of disulfide-bonded proteins; (ii) presence in KS51 of non-waxy starch and the accompanying granule-bound starch synthase; and (iii) the differing nature of the protein matrix and its interaction with starch. The current findings suggest that each of these factors should be considered in efforts to enhance the nutritional value of sorghum grain. 相似文献
127.
Ee Ding Wong Min Zhang Guangping Han Shuichi Kawai Qian Wang 《Journal of Wood Science》2000,46(3):202-209
Two main types of fiberboards were produced using lauan (Shorea spp.) fibers with an isocyanate resin as the binder; fiberboard with a flat, homogeneous (homoprofile), and typical U-shaped (conventional) density profile along the board thickness. The processing parameters included manipulation of mat moisture content distribution, press closing speed, and hot pressing method. The results are summarized as follows: (1) A larger variation was observed in the peak density (PD) and core density (CD) of fiberboards at 0.5g/cm3 mean density (MD) level than in those at 0.7 g/cm3. Generally, PD showed a greater variation than CD, irrespective of MD level. (2) Boards produced using two-step hot pressing recorded substantially higher PD with reduced CD. (3) Multiple regression analysis showed that CD and PD could be calculated based on the other profile defining factors, and a rough estimation for peak distance and gradient factor was possible. (4) Based on static bending, conventional fiberboard had a higher modulus of rupture (MOR) than the homo-profile board but a similar modulus of elasticity (MOE). (5) At 0.5 g/cm3 the MOR and dynamic MOE of fiberboard increased by up to 67% and 62%, respectively, when the PD increased from 0.5 to 1.07 g/cm3. Similarly, an increase of PD from 0.7 to 1.1 g/cm3 resulted in corresponding increases of 55% and 34% in the MOR and dynamic MOE of 0.7 g/cm3 boards. (6) The internal bond strength and screw withdrawal resistance were almost entirely dependent on the CD and MD, respectively. (7) Homo-profile fiberboards registered higher thickness swelling and water absorption than conventional fiberboards throughout the dry/wet conditioning cycle. 相似文献
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Conidia of Cochliobolus sativus and five other pigmented fungi lysed when incubated in natural soil. Lysis followed perforation of the spore wall by holes of varying dia. Three possible causes of perforation were investigated, namely autolysis, mechanical puncture by soil animals and enzymatic erosion by soil micro-organisms. Results indicated that soil micro-organisms were the likely causal agents although no micro-organism able to perforate conidia has yet been isolated. Colonization of conidia by the soil microflora was studied by electron microscopy. On the basis of these direct observations, possible perforation mechanisms are suggested. Reports of perforation of fungal, plant and bacterial cell walls are briefly summarized and the perforation phenomenon discussed in relation to the biodegradation of pigmented fungal propagules in soils. 相似文献
130.