全文获取类型
收费全文 | 551篇 |
免费 | 19篇 |
国内免费 | 20篇 |
专业分类
林业 | 126篇 |
农学 | 15篇 |
基础科学 | 8篇 |
79篇 | |
综合类 | 38篇 |
农作物 | 33篇 |
水产渔业 | 56篇 |
畜牧兽医 | 170篇 |
园艺 | 20篇 |
植物保护 | 45篇 |
出版年
2024年 | 2篇 |
2023年 | 6篇 |
2022年 | 32篇 |
2021年 | 27篇 |
2020年 | 18篇 |
2019年 | 14篇 |
2018年 | 16篇 |
2017年 | 15篇 |
2016年 | 12篇 |
2015年 | 21篇 |
2014年 | 27篇 |
2013年 | 32篇 |
2012年 | 35篇 |
2011年 | 38篇 |
2010年 | 15篇 |
2009年 | 17篇 |
2008年 | 29篇 |
2007年 | 48篇 |
2006年 | 23篇 |
2005年 | 32篇 |
2004年 | 25篇 |
2003年 | 25篇 |
2002年 | 11篇 |
2001年 | 17篇 |
2000年 | 15篇 |
1999年 | 5篇 |
1998年 | 14篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1995年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有590条查询结果,搜索用时 15 毫秒
101.
Paddy and Water Environment - This study investigates the erosion condition of irrigation earth structures and determines the measures for erosion protection in Cambodia paddy farming regions. Most... 相似文献
102.
In vitro cultured shoots of three Chinese poplar species (Populus tomentosa, P. alba cv. Pyramidalis andP. euphratica) and an improved poplar (FS-51), as a control, were exposed to the stress of low osmotic potential, salinity and high pH,
and the shoot growth was measured.P. tomentosa andP. euphratica could grow even under the high osmotic stress (0.5m mannitol; −1.7 MPa).P. euphratica shoots which were previously cultured on the medium containing 0.7m mannitol (−2.4 MPa) recovered its growth after being transplanted to the medium without mannitol. The shoot growth ofP. euphratica was not so reduced even on the medium containing 100 mM NaCl. However, growth of the other poplars markedly reduced with
10 mM NaCl. Medium pH (pH 5.8–10) also did not affect the shoot growth ofP. euphratica. These poplars have different tolerance to the stresses in cultured shootin vitro. P. euphratica was extremely tolerant to the stresses which are possible to damage plants in dry land.
A part of this study was presented at the 104th Annual Meeting of the Japanese Forestry Society. (1993). 相似文献
103.
Yanni Sudiyani Sakae Horisawa Keli Chen Shuichi Doi Yuji Imamura 《Journal of Wood Science》2002,48(6):542-547
Changes in mold populations and genera on the exposed surfaces of tropical hardwoods — albizia (Paraserianthes falcata), kapur (Dryobalanop lanceolata), mahoni (Switenia macrophylla), nangka (Artocarpus heterophyllus), puspa (Schima wallchii) — were investigated. The wood specimens were exposed to the Indonesian climate for 32 weeks. Properties including mass loss, wettability, mold growth (colony-forming units), and mold genera were evaluated. The change in properties after exposure was significantly affected by the wood species, but there was no clear relation between mass loss and the initial chemical components or between wettability and wood density. The number of mold populations was different by exposure period and wood species, but there was no significant effect of climate conditions, such as rainfall and ultraviolet radiation. Of the genera identified,Aureobasidium, Cladosporium, andPenicillium were dominant molds on the exposed wood surfaces. 相似文献
104.
S. Nami?KartalEmail author Erman?Munir Tomo?Kakitani Yuji?Imamura 《Journal of Wood Science》2004,50(2):182-188
This study evaluated oxalic acid accumulation and bioremediation of chromated copper arsenate (CCA)-treated wood by three brown-rot fungi Fomitopsis palustris, Coniophora puteana, and Laetiporus sulphureus. The fungi were first cultivated in a fermentation broth to accumulate oxalic acid. Bioremediation of CCA-treated wood was then carried out by leaching of heavy metals with oxalic acid over a 10-day fermentation period. Higher amounts of oxalic acid were produced by F. palustris and L. sulphureus compared with C. puteana. After 10-day fermentation, oxalic acid accumulation reached 4.2 g/l and 3.2 g/l for these fungi, respectively. Fomitopsis palustris and L. sulphureus exposed to CCA-treated sawdust for 10 days showed a decrease in arsenic of 100% and 85%, respectively; however, C. puteana remediation removed only 18% arsenic from CCA-treated sawdust. Likewise, chromium removal in F. palustris and L. sulphureus remediation processes was higher than those for C. puteana. This was attributed to low oxalic acid accumulation. These results suggest that F. palustris and L. sulphureus remediation processes can remove inorganic metal compounds via oxalic acid production by increasing the acidity of the substrate and increasing the solubility of the metals.An erratum to this article can be found at 相似文献
105.
Kengo Ishimaru Toshimitsu Hata Paul Bronsveld Takashi Nishizawa Yuji Imamura 《Journal of Wood Science》2007,53(5):442-448
Japanese cedar (Cryptomeria japonica) preheated at 700°C was subsequently heated to 1800°C and characterized by electron microscopy, X-ray diffraction, and micro-Raman
spectroscopy. The degree of disorder of carbon crystallites and the amount of amorphous phase decreased considerably with
an increase in heat treatment temperature to 1400°C, while carbon crystallites clearly developed above this temperature, showing
that the microstructure of carbonized wood undergoes drastic changes around 1400°C. Besides showing the bands for sp2-bonded carbon, the Raman spectra showed a shoulder near 1100 cm−1 assigned to sp3-bonded carbon. With an increase of heat treatment temperature, the peak position of the Raman sp3 band shifted to a lower frequency from 1190 to 1120 cm−1, which is due to the transformation of sp3-bonded carbon from an amorphous phase to a nanocrystalline phase. These data showed that the microstructure of carbonized
wood from 700° to 1800°C consisted of the combination of sp2- and sp3-bonded carbon, which is probably due to the disordered microstructure of carbonized wood. It is suggested that the sp3-bonded carbon is transformed from an amorphous structure to a nanocrystalline structure with the growth of polyaromatic stacks
at temperatures above 1400°C. 相似文献
106.
Tomoe?NakayamaEmail author Tsuyoshi?Yoshimura Yuji?Imamura 《Journal of Wood Science》2004,50(6):530-534
Two species of Japanese subterranean termite, Coptotermes formosanus Shiraki and Reticulitermes speratus (Kolbe), were used in an investigation of the optimum temperature–relative humidity (RH) combination for their feeding activities. Daily wood consumption per worker and survivals were measured, and the protozoan fauna in the hindgut were observed under 15 temperature–RH combinations for 1 week. Five temperatures (20°, 25°, 30°, 35°, and 40°C) and three RH conditions (50%, 70%, and 90% RH) were examined. The activities of the workers were highest at around 30°C for both species, and workers died at 40°C within 5 days and 2 days for C. formosanus and R. speratus, respectively. The optimum RH condition for feeding activity was 90% RH for C. formosanus and 70%–90% RH for R. speratus. The optimum temperature–RH combinations for feeding activities were 30°C at 90% RH for C. formosanus and 30°C at 70%–90% RH for R. speratus. 相似文献
107.
108.
Adsorption capacities and related characteristics of wood charcoals carbonized using a one-step or two-step process 总被引:2,自引:0,他引:2
Lilibeth Pulido-Novicio Toshimitsu Hata Yasuji Kurimoto Shuichi Doi Shigehisa Ishihara Yuji Imamura 《Journal of Wood Science》2001,47(1):48-57
Sugi (Cryptomeria japonlca D. Don) wood powder was carbonized at varying temperatures by a onestep process up to 1000C and a two-step process using wood charcoal as the raw material up to 1600C. This study was conducted to evaluate the adsorptive properties of wood charcoal and discuss the mechanism of its adsorptive function in relation to the physical and anatomical characteristics of wood after carbonization. Anatomical characteristics of carbonized wood materials were directly observed under heating using an environmental scanning electron microscope (ESEM); the cell wall structures were analyzed by high-resolution transmission electron microscope (HRTEM). The largest weight losses were observed at the highest temperatures, in both the one-step and twostep processes but leveled off above 800C. Shrinkages in the tangential, radial, and longitudinal directions increased with carbonization temperature, peaking at 1000C. Direct observations by ESEM showed distinct shrinkage at around 400C. The first trial observations by HRTEM on the changes in the ultrastructure of cell walls of wood charcoals were done, and it was assumed to affect the formation of micropores. Adsorption was found to follow the Langmuir isotherm model. With the one-step carbonization process, the iodine adsorption capacities of the carbonized wood powders increased with increasing carbonization temperature, peaking at 800C, but decreased at higher temperatures. The wood powder carbonized at 1000C with the two-step process showed the highest capacity, but further heating up to 1400C drastically decreased the adsorption. The shrinkage of cells was related to the increases and decreases in its specific surface area. Specific surface area and total pore volume were evidently related to the adsorptive properties.Part of this paper was presented at the Second International Wood Science Seminar, Indonesia, November 6–7, 1998 相似文献
109.
Lilibeth Pulido-Novicio Yasuji Kurimoto Masakazu Aoyama Kazuto Seki Shuichi Doi Toshimitsu Hata Shigehisa Ishihara Yuji Imamura 《Journal of Wood Science》2001,47(2):159-162
The ability of sugi wood carbonized at 1000°C to adsorb mercury was examined using aqueous solutions of mercuric chloride. Parameters studied include contact time, pH, adsorption temperature, and initial concentration of mercury in solution. Results showed that sugi wood carbonized at 1000°C could effectively remove mercury from aqueous solutions. The carbonized wood showed high adsorption ability for mercury at a wide pH range (pH 3–9), but its ability drastically decreased at pH 11. Adsorption decreased with increases in adsorption temperatures, indicating that the processes were exothermic in nature. Adsorption was found to follow the Freundlich isotherm model. The adsorption capacity of carbonized sugi wood was comparable to that of commercial activated carbon. 相似文献
110.
Molecular cloning of tropomyosins identified as allergens in six species of crustaceans 总被引:1,自引:0,他引:1
Motoyama K Suma Y Ishizaki S Nagashima Y Shiomi K 《Journal of agricultural and food chemistry》2007,55(3):985-991
Although tropomyosin is known to be a major allergen of crustaceans, its structural information is limited to only five species. In this study, tropomyosin was confirmed to be a major allergen in six species of crustaceans (black tiger prawn, kuruma prawn, pink shrimp, king crab, snow crab, and horsehair crab) by immunoblotting. Then, the amino acid sequences of tropomyosins from these crustaceans were elucidated by a cDNA cloning technique. Sequence data for crustacean tropomyosins including the obtained results reveal that fast tropomyosins are contained in shrimps (or prawns) and lobsters, slow tropomyosins in crabs, and both tropomyosins in crayfishes and hermit crabs. Although fast and slow tropomyosins share a high sequence identity (about 90%) with each other, significant differences are observed in specific regions between both tropomyosins. 相似文献