全文获取类型
收费全文 | 538篇 |
免费 | 23篇 |
专业分类
林业 | 22篇 |
农学 | 9篇 |
77篇 | |
综合类 | 54篇 |
农作物 | 35篇 |
水产渔业 | 24篇 |
畜牧兽医 | 289篇 |
园艺 | 23篇 |
植物保护 | 28篇 |
出版年
2023年 | 4篇 |
2022年 | 2篇 |
2021年 | 8篇 |
2020年 | 12篇 |
2019年 | 15篇 |
2018年 | 11篇 |
2017年 | 5篇 |
2016年 | 12篇 |
2015年 | 14篇 |
2014年 | 11篇 |
2013年 | 27篇 |
2012年 | 28篇 |
2011年 | 29篇 |
2010年 | 10篇 |
2009年 | 22篇 |
2008年 | 36篇 |
2007年 | 30篇 |
2006年 | 38篇 |
2005年 | 51篇 |
2004年 | 38篇 |
2003年 | 36篇 |
2002年 | 37篇 |
2001年 | 7篇 |
2000年 | 3篇 |
1999年 | 7篇 |
1998年 | 3篇 |
1997年 | 7篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1972年 | 1篇 |
排序方式: 共有561条查询结果,搜索用时 31 毫秒
81.
Shannon M. Snyder Richard M. Low Janet C. Stocks Dennis L. Eggett Tory L. Parker 《Plant foods for human nutrition (Dordrecht, Netherlands)》2012,67(4):358-364
Raspberries contain flavonoid antioxidants whose relative concentrations may vary between the juice, pulp, and seed fractions. Oxygen radical absorbance capacity (ORAC), total anthocyanin content, and berry color were determined for six cultivars of primocane raspberries grown in a dry climate (Utah, USA). Significant ORAC differences were found between juice (18.4?±?0.39 μmol TE/g), pulp (24.45?±?0.43), and seeds (273.27?±?11.15) with all Utah cultivars combined. A significantly higher concentration of anthocyanins was present in Utah raspberry juice (20.86?±?0.35 mg cyanidin-3-glucoside eq./100 g), compared to pulp (13.96?±?0.35). Anthocyanin content of juice and pulp were significantly positively correlated with dark color (L*). This is the first report of fractional differences in dry climate raspberries, and has implications for the juice and supplement industries. 相似文献
82.
Nesar Ahmed Janet H. Brown James F. Muir 《Aquaculture Economics & Management (Blackwell Science)》2013,17(3):207-223
The livelihoods of a large number of farmers are associated with freshwater prawn (Macrobrachium rosenbergii) farming in gher (modified rice fields with high, broad peripheral dikes) systems in southwest Bangladesh. Most farmers integrated prawn with fish and rice in their gher and followed extensive methods using low inputs. Although farmers have improved their social and economic conditions through prawn farming, constraints include high production costs, low supply of wild fry and snail meat as prawn feed, lack of technical knowledge of farmers, and negative environmental impacts. 相似文献
83.
Saraid Mora-Rochin Janet A. Gutirrez-Uribe Sergio O. Serna-Saldivar Pedro Snchez-Pea Cuauhtmoc Reyes-Moreno Jorge Miln-Carrillo 《Journal of Cereal Science》2010,52(3):502-508
The effects of traditional nixtamalization and extrusion cooking on total phenolics, ferulic acid, anthocyanins and Oxygen Radical Absorbance Capacity (ORAC) of Mexican pigmented (blue and red) and commercial (white and yellow) maize processed into tortillas were investigated. Tortillas prepared from extruded flours retained between 76.2–93.9% and 58–96.7% of total phenolics and total ferulic acid (TFA) respectively, compared to 50.5–75.7% and 19.6–55.8% assayed in traditional tortillas. Approximately 97–99% of TFA in raw kernels and their tortillas was in its bound form. The retention of TFA in traditional tortillas was significantly lower compared to tortillas from extruded flours. Traditional tortillas contained more free ferulic acid compared to tortillas produced from extruded flours indicating that the first process liberated bound ferulic acid with cell walls more efficiently. Blue maize lost more than 55% of the anthocyanins when processed into extruded or traditional tortillas. Approximately 68–92% of the ORAC associated with raw kernels or their tortillas was due to bound compounds. Traditional and extruded tortillas lost 16.4–52.4% and 6.8–24.8%, respectively, of the total ORAC associated with raw grains. Results clearly indicate that the proposed lime-cooking extrusion strategy was instrumental in retaining higher levels of phytochemicals, particularly ferulic acid, and antioxidants in all tortillas. 相似文献
84.
Jef Dupain Janet Nackoney J. Mario Vargas Paul J. Johnson Miguel A. Farfán Mange Bofaso Julia E. Fa 《Biological conservation》2012,146(1):32-40
Ever-increasing rates of subsistence and commercial bushmeat hunting in African moist forests result in unsustainable exploitation levels for many mammals. Bushmeat markets are found in a large number of human settlements throughout the region and may be used to monitor the state of game species in catchment areas. As depletion of large-bodied species forces hunters to focus on small-bodied species this is likely to be reflected in the mean body mass and species composition of animals sold in that market. In this paper we present data on bushmeat sold in Basankusu market in the Democratic Republic of Congo during a 2-year period (276 sample days). We counted 10,358 carcasses of 33 mammal taxa, emerging from nine well-defined hunting catchment zone; an area of more than 45,000 km2. For each catchment we assessed human pressures using metrics derived from remote sensing. Human population density correlated with higher species richness of species harvested, as well as with an increase in rarer taxa, and with a tendency for more individuals with higher intrinsic rates of reproduction to be observed. We suggest that simple surrogates of anthropogenic pressure and faunal characteristics in markets can be used as a rapid tool to measure faunal depletion of mammals at a regional scale. Such a system of evidence-based game monitoring would allow identification of both potentially overhunted and of less-disturbed areas for consideration in strategic planning. 相似文献
85.
86.
Janczyk P Weigner J Luebke-Becker A Richardson KC Plendl J 《Berliner und Münchener tier?rztliche Wochenschrift》2011,124(5-6):225-227
Most embalming of cadavers for anatomical dissection in veterinary medicine has used 6-10% formaldehyde resulting in discoloured and rigid specimens. This project produced teaching specimens of sheep, horse and calf cadavers having their musculoskeletal and visceral structures with a natural appearance using a fixation solution with lowered concentrations of formaldehyde (2% and 3%) together with ethanol and polyethylene glycols. Fixation parameters (palpable consistency, flexibility, colour, tissue hydration and odour) were assessed qualitatively by twice weekly dissections over two months for sheep and three months for horses and calf. Formaldehyde levels, measured in the breathing zone, were below the maximum allowable concentration in all specimens except for a 300 kg horse cadaver. To evaluate the effectiveness of the fixation solution in microbial inhibition, tissue samples were taken and analyzed for the presence of culturable aerobic and anaerobic bacteria, yeasts and moulds. Single colonies of Pseudomonas oryzihabitans, Chryseobacterium sp., Acinetobacter sp. were isolated from lungs, and Micrococcus sp. and Bacillus sp. were isolated from one muscle sample. 相似文献
87.
Anthea L. Katelaris Keira Glasgow Kerryn Lawrence Paul Corben Anthony Zheng Suhasini Sumithra John Turahui Janet Terry Debra van den Berg Daneeta Hennessy Stacey Kane Scott B. Craig Ellena Heading Mary‐Anne Burns Hanisah L. Corner Vicky Sheppeard Jeremy McAnulty 《Zoonoses and public health》2020,67(1):35-43
88.
89.
Soybean nodules subjected to water stress showed lowered C2H2 reducing activity and O2 uptake, but enhanced CO2 and ethanol evolution. Similar results were obtained with waterlogged nodules. The effects of stress could be partially or completely overcome by increaseing the O2 supply. It is concluded that both water deficiency and excess may depress nitrogenase activity (C2H2 reduction) by restricting supplies of intermediates from aerobic pathways. At the same time fermentative pathways are stimulated and could lead to inhibitory concentrations of ethanol being produced. Both symbionts possess systems for ethanol production. 相似文献
90.
A method tor direct visual or photomicrographic enumeration of soil propagules in soil-agar films and soil smears, stained with a mixture ofeuropium(III) ttienoyltrifluoroacetonate and the disodium salt of 4,41-bis(4-anilino-6-bis(2-hydroxyethyl)amino-S-triazin-2-ylamino)2,21-stilbene disulphonic acid, abbreviated to Eu(TTA)3 and fluorescent brightener (FB), respectively, is described.Soil-agar suspensions at 55–60°C were introduced into haemocytometer sample chambers of 100 μm and 20 μm depth which gave soil-agar film thicknesses of 25 μm and 12 μm, respectively, after air-drying. Soil smears air-dried on 1.25 cm2 and 1.0 cm2 areas of glass slide were 5.2–6.0 μm and 6.0–8.0 μm thick, respectively.The Eu(TTA)3 is best formulated in 50% (v/v) ethanol. The best concentrations of Eu(TTA)3 and FB for staining soil propagules were 2 mM and 25 μM. respectively. A staining period of 18 h for soil-agar films and 90–120 min for soil smears was found to be optimal. The optimum volumes of 50% ethanol for rinsing soil-agar films and soil smears were found to be 12.5 and 5.0 ml. respectively.Lack of in-depth focusing on agar films 25 μm thick resulted in 15–17 per cent error in enumerations. The 12 μm agar films and soil smears required little in-depth focusing and were acceptable for photomicrographic recording of numbers of soil propagules. It is concluded that incident u.v. photomicrographic recording of soil propagule numbers in thin agar films or soil smears is a practical solution to operator fatigue likely to occur during direct microscopy. 相似文献