全文获取类型
收费全文 | 331篇 |
免费 | 20篇 |
专业分类
林业 | 23篇 |
农学 | 10篇 |
基础科学 | 3篇 |
73篇 | |
综合类 | 43篇 |
农作物 | 25篇 |
水产渔业 | 22篇 |
畜牧兽医 | 91篇 |
园艺 | 34篇 |
植物保护 | 27篇 |
出版年
2023年 | 2篇 |
2022年 | 7篇 |
2021年 | 9篇 |
2020年 | 19篇 |
2019年 | 11篇 |
2018年 | 13篇 |
2017年 | 12篇 |
2016年 | 17篇 |
2015年 | 6篇 |
2014年 | 14篇 |
2013年 | 19篇 |
2012年 | 23篇 |
2011年 | 28篇 |
2010年 | 20篇 |
2009年 | 11篇 |
2008年 | 21篇 |
2007年 | 23篇 |
2006年 | 10篇 |
2005年 | 15篇 |
2004年 | 11篇 |
2003年 | 9篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1985年 | 1篇 |
1984年 | 6篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1969年 | 1篇 |
1955年 | 1篇 |
1933年 | 1篇 |
排序方式: 共有351条查询结果,搜索用时 15 毫秒
281.
Murcia MA Egea I Romojaro F Parras P Jiménez AM Martínez-Tomé M 《Journal of agricultural and food chemistry》2004,52(7):1872-1881
The antioxidant properties of seven dessert spices (anise, cinnamon, ginger, licorice, mint, nutmeg, and vanilla) were compared with those of the common food antioxidants butylated hydroxyanisole (BHA) (E-320), butylated hydroxytoluene (BHT) (E-321), and propyl gallate (E-310). The influence of irradiation process on antioxidant activity was also evaluated. Mint and cinnamon exhibited a higher percentage of inhibition of oxidation than the other spices analyzed and the food antioxidants, as tested by the lipid peroxidation assay (LOO*). Nutmeg, anise, and licorice showed the strongest protection in the deoxyribose assay (OH*). Vanilla exhibited the highest antioxidant activity in the peroxidase-based assay (H2O2). Nutmeg, propyl gallate, ginger, and licorice improved the stability of oils (sunflower, corn, and olive) and fats (butter and margarine) against oxidation (110 degrees C Rancimat). Cinnamon was a better superoxide radical scavenger than the other analyzed spices and additives. When the Trolox equivalent antioxidant capacity (TEAC) assay was used to provide a ranking order of antioxidant activity, the result in decreasing order of antioxidant capacity was cinnamon approximately equal to propyl gallate > mint > anise > BHA > licorice approximately equal to vanilla > ginger > nutmeg > BHT. Irradiated samples did not show significant differences (p < 0.05) in the antioxidant activity with respect to the non-irradiated samples (1, 3, 5, and 10 kGy) in the assays used. 相似文献
282.
Casmir Onwuaso Igbokwe Umar Muhammed Bello Felix Ejikeme Mbajiorgu 《Anatomia, histologia, embryologia》2021,50(3):448-458
The morphology of tongue in straw-coloured fruit bat from tropical forests was evaluated in relation to frugivorous diets and in comparison with other species that consumes other food types. Gross, stereomicroscopy, scanning electron microscope and histological methods were used. The tongue was relatively long with round tip, which closely fitted into oral cavity. Five types of mechanical papillae included crown-like and trifid filiform papillae. Also bulky, cone-shaped papillae and long conical papillae were identified. These mechanical types also showed variations in shape, size and number of processes of papillae. Transitional forms of these mechanical papillae were present. Fungiform papillae with taste pores were interposed amongst filiform types in apex and body; three ovoid-shaped vallate papillae were in triangular arrangement on root and displayed taste pores. Some bulky, cone-shaped papillae surrounded the vallate papillae. Histologically, mechanical filiform types showed highly keratinized stratified squamous epithelium and dense connective tissue core with secondary papillae. Taste buds appeared in fungiform and vallate papillae. Neutral and acidic secretions were identified in lingual glands of root. The presence of prominent filamentous processes of filiform papillae and conical papillae of the tongue in conjunction with gustatory papillae ensures adaptation to copious fruit diets. The gross morphometric and histometric parameters of the tongue did not differ remarkably from previous values obtained for some fruit bats with comparable weight. This investigation showed similarities with fruit bats such as large flying fox and Egyptian fruit bat and reflect common diet and feeding habits but varied from insectivorous and nectivorous bats. 相似文献
283.
Emmanuel Ortese Paul Kayode Baiyeri Felix Detuhan Ugese 《Journal of Crop Science and Biotechnology》2011,14(4):321-327
The nutrient mining abilities of six Musa genotypes: ‘Agbagba’, ‘PITA 22’, ‘Nsukka Local’, ‘FHIA 17’, ‘Fougamou’, and ‘BITA 7’, grown in organic medium formulated
by decomposing rice husks with poultry manure in volume proportions of 3:2, were determined at the Teaching and Research Farm
of the Department of Crop Science, University of Nigeria, Nsukka, Nigeria. Results indicated significant variation in nutrient
mining with respect to Musa genotype and duration of growth. The medium previously cropped with ‘Agbagba’ recorded highest residual mean values for P
and Ca, while the medium cropped with ‘Fougamou’ had the highest residual concentration of Mg and S. Residual amount of K
was highest in the medium where ‘PITA 22’ and ‘Nsukka Local’ were previously grown. Peak residual concentration of P and K
occurred in the medium in which Musa plants were grown only for 4 months, decreasing thereafter, in contrast to Ca, Mg, and S. Residual N tended to increase with
longer growth duration of the Musa crops. Follower crop of maize grown in the medium previously cropped with Musa genotypes showed variable performance. While
medium previously cropped with ‘PITA 22’ and ‘BITA 7’ favored growth attributes and leaf greenness of the follower maize plant,
‘Fougamou’ favored maize fresh weight attributes. Ectomycorrhiza association was observed in medium previously cropped to
‘BITA 7’ and ‘PITA 22’. Generally, ‘Agbagba’ and ‘Fougamou’ seemed to be the most reticent nutrient miners while uptake of
P and K appeared to be low 4 months after planting (MAP) in contrast to Ca, Mg, and S uptake. However, substrate previously
cropped with ‘PITA 22’, ‘BITA 7’ and ‘Fougamou’ gave rise to superior growth and fresh weight attributes, respectively, of
the maize, the follower crop. A prospect of utilizing the ectomycorrhiza association observed with some genotypes to upgrade
Musa yields and those of associated or follower crops exist. 相似文献
284.
Estimating habitat suitability and potential population size for brown bears in the Eastern Alps 总被引:1,自引:0,他引:1
Denise Güthlin Felix Knauer Thomas Kneib Helmut Küchenhoff Petra Kaczensky Georg Rauer Marko Jonozovi? Andrea Mustoni Klemen Jerina 《Biological conservation》2011,(5):1733-1741
According to the Habitats Directive of the European Union, a favorable conservation status for the brown bear (Ursus arctos) should be targeted at the population level in large contiguous habitats such as the Alps, the largest mountain range in Europe. However, in most of the Alps brown bears are extinct and habitat suitability in these areas is often questionable. For this paper, radio-tracking data from four projects with 42 individual bears was compiled to assess habitat suitability. Discrete-choice models with random bear effects were fitted and compared to results obtained from compositional analysis and logistic regression. Sound definition of the available area in the discrete-choice model turned out to be essential. Brown bears showed a preference for forested and steep habitats and an avoidance of roads.Results from the three approaches were used to predict habitat suitability across the entire range of the Eastern Alps. Minimum potential population size was projected based on observed densities in Trentino and Central Austria, and ranged from 1228 to 1625 individuals, with 518–686 mature bears. This would satisfy a favorable conservation status. The developed methodology also has wide applicability to quantification of habitat suitability and potential population size in other cases where species are at risk. 相似文献
285.
Usually spices are identified morphologically using simple methods like magnifying glasses or microscopic instruments. On the other hand, molecular biological methods like the polymerase chain reaction (PCR) enable an accurate and specific detection also in complex matrices. Generally, the origins of spices are plants with diverse genetic backgrounds and relationships. The processing methods used for the production of spices are complex and individual. Consequently, the development of a reliable DNA-based method for spice analysis is a challenging intention. However, once established, this method will be easily adapted to less difficult food matrices. In the current study, several alternative methods for the isolation of DNA from spices have been developed and evaluated in detail with regard to (i) its purity (photometric), (ii) yield (fluorimetric methods), and (iii) its amplifiability (PCR). Whole genome amplification methods were used to preamplify isolates to improve the ratio between amplifiable DNA and inhibiting substances. Specific primer sets were designed, and the PCR conditions were optimized to detect 18 spices selectively. Assays of self-made spice mixtures were performed to proof the applicability of the developed methods. 相似文献
286.
Background
Prenylquinones are key compounds of the thylakoid membranes in chloroplasts. To understand the mechanisms involved in the response of plants to changing conditions such as high light intensity, the comprehensive analysis of these apolar lipids is an essential but challenging step. Conventional methods are based on liquid chromatography coupled to ultraviolet and fluorescence detection of a single or limited number of prenylquinones at a time. Here we present an original and rapid approach using ultra-high pressure liquid chromatography-atmospheric pressure chemical ionization-quadrupole time-of-flight mass spectrometry (UHPLC-APCI-QTOFMS) for the simultaneous profiling of eleven prenylquinones in plant tissues, including α-tocopherol, phylloquinone, plastochromanol-8 and plastoquinone-9.Results and discussion
Mass spectrometry and chromatography parameters were optimized using pure standards. Sample preparation time was kept to minimum and different extraction solvents were evaluated for yield, ability to maintain the redox state of prenylquinones, and compatibility with chromatography. In addition to precise absolute quantification of 5 prenyllipids for which standards were available, relative quantification of 6 other related compounds was possible thanks to the high identification power of QTOFMS. Prenylquinone levels were measured in leaves of Arabidopsis grown under normal and high light intensities. Quantitatively, the obtained results were consistent with those reported in various previous studies, demonstrating that this new method can profile the full range of prenylquinones in a very short time.Conclusion
The new profiling method proves faster, more sensitive and can detect more prenylquinones than current methods based on measurements of selected compounds. It enables the extraction and analysis of twelve samples in only 1.5 h and may be applied to other plant species or cultivars. 相似文献287.
Felix Diaz González Rodrigo Mui?o Víctor Pereira Rómulo Campos José Luis Benedito 《Journal of veterinary science (Suw?n-si, Korea)》2011,12(3):251-255
Blood indicators are used as a tool to diagnose metabolic disorders. The present work was conducted to study the relationships among blood indicators of lipomobilization and hepatic function in high-yielding dairy cows. Two groups of Holstein cows were studied: 27 early lactation cows and 14 mid lactation cows from four different herds with similar husbandry characteristics in Galicia, Spain. Blood samples were obtained to measure beta-hydroxybutyrate (BHB), non-esterified fatty acids (NEFA), triglycerides (TG), and the activity of aspartate transaminase (AST) and gamma-glutamyl transferase. Cows in early lactation had higher levels of BHB and NEFA than mid lactation cows. High lipomobilization (NEFA > 400 µmol/L) was detected in 67% and 7% of early lactation and mid lactation cows, respectively, while subclinical ketosis (BHB > 1.2 mmol/L) was detected in 41% and 28% of the early lactation and lactation cows, respectively. TG concentrations were low in all cows suffering subclinical ketosis and in 61% of the cows with high lipomobilization. During early lactation, 30% of cows suffered hepatic lipidosis as detected by levels of AST. Compromised hepatic function was observed in early lactation cows as shown by lower concentrations of glucose, total protein, and urea. 相似文献
288.
Energy density in growing diets may affect carcass quality of cattle; however, few reports have described the impact of energy source. The objectives of this research were to determine effects of source [dried distillers grains with solubles (DDGS) vs. corn] and amount (limit-fed to gain 0.9 vs. 1.4 kg of BW/d) of energy during the growing phase on feedlot performance and marbling. Angus-cross steers (144 head) were blocked by BW (average initial BW = 252 ± 36 kg), allotted within each block to 8 pens (6 steers/pen, 24 pens total), and randomly assigned to 1 of 4 feeding systems in a 2 × 2 factorial arrangement of treatments: 1) 65% DDGS fed to gain 0.9 kg of BW/d, 2) 65% DDGS fed to gain 1.4 kg of BW/d, 3) 65% corn fed to gain 0.9 kg of BW/d, and 4) 65% corn fed to gain 1.4 kg of BW/d. Fecal grab samples were collected on d 52 of the growing phase to determine digestibility of DM, ADF, NDF, ether extract (EE), and CP. After the 98-d growing phase, all steers were fed the same finishing diet. Steers were slaughtered by pen when average BW within the pen was 544, 522, and 499 kg for the large, medium, and small BW blocks, respectively. Average daily gain and DMI differed (P<0.01) by design during the growing phase. Compared with the corn-based diets, digestibilities of DM, NDF, and EE were decreased (P<0.02) when DDGS-based diets were fed during the growing phase, whereas the digestibility of N was increased (P<0.01). The ADG was greatest (P=0.02) during the finishing phase for steers fed to gain 0.9 kg of BW/d initially, but source of energy during the growing phase did not affect (P=0.24) finishing phase ADG. Steers fed to gain 0.9 kg of BW/d during the growing phase also had less backfat (P=0.08), decreased USDA yield grades (P=0.03), and greater LM area (P<0.01) than steers fed to gain 1.4 kg of BW/d. There was an interaction between energy source and amount for marbling scores (P=0.02). Steers fed corn-based diets to gain 0.9 kg of BW/d during the growing phase had the most marbling, whereas those fed to gain 0.9 kg of BW/d on DDGS had the least marbling; the remaining feeding systems were intermediate. Overall ADG and DMI were affected (P < 0.06) by both source and amount of energy fed during the growing phase. Feeding the DDGS-based diet to achieve greater ADG during the growing phase increased marbling, whereas feeding the corn-based diet to increase ADG during the growing phase decreased marbling. 相似文献
289.
Radunz AE Fluharty FL Susin I Felix TL Zerby HN Loerch SC 《Journal of animal science》2011,89(2):478-488
Mature pregnant crossbred ewes (n = 90) were used in a randomized complete block design experiment and were assigned to 1 of 3 winter-feeding systems differing in primary feed source: haylage (HL), limit-fed corn (CN), or limit-fed dried distillers grains (DDGS). Effects of these winter-feeding strategies on postweaning progeny performance were determined. Lamb progeny (n = 96) were weaned at 61 ± 4 d of age and fed a common high-concentrate diet. Lambs were assigned to feedlot pen (n = 18) based on dam mid-gestation pen. Growth rate, DMI, and ADG were determined for the first 40 d of the finishing period. At 96 ± 4 d of age, 1 wether lamb was randomly selected from each pen (n = 18) for a glucose tolerance test. The experiment was terminated, and lambs were slaughtered individually when they were determined to have achieved 0.6-cm 12th-rib fat thickness. After a 24-h chill, carcass data were collected and a 2.54-cm chop was removed from each lamb from the LM posterior to the 12th rib for ether extract analysis. Additional carcass measurements of bone, muscle, and fat from the shoulder, rack, loin, and leg were collected on 35 carcasses. At weaning, lamb BW was not different among treatments, whereas final BW tended to be greater (P = 0.09) for lambs from ewes fed DDGS and CN during gestation than from those fed HL. Overall lamb growth rate from birth to slaughter was not different among treatments. Lambs from ewes fed DDGS vs. CN or HL tended to have a greater initial insulin response (P = 0.09). Dressing percent was less (P = 0.04) in lambs from ewes fed DDGS, but no difference (P = 0.16) was detected in HCW among treatments. As expected, 12th rib fat thickness was similar among treatments, whereas LM area was largest to smallest (P = 0.05) in lambs from ewes fed CN, HL, and DDGS, respectively. Proportion of internal fat tended to be greatest to smallest (P = 0.06) in lambs from ewes fed DDGS, CN, and HL, respectively. Calculated boneless trimmed retail cuts percentage was less (P = 0.04) in lambs from ewes fed DDGS than CN or HL. Loin muscle weight as a percentage of wholesale cut tended (P = 0.10) to be greater in lambs from ewes fed CN and HL than DDGS, whereas other muscle, bone, and fat weights and proportions were similar (P > 0.24) among treatments. Prepartum diet during mid to late gestation of ewes altered postnatal fat and muscle deposition and may be associated with alterations in insulin sensitivity of progeny. 相似文献
290.
Cândido TC Perri SH Gerzoschkwitz Tde O Luvizotto MC de Lima VM 《Veterinary parasitology》2008,157(3-4):175-181
This study evaluated the performance of crude total antigen (CTA) and fucose-mannose ligand antigen (FML) in an enzyme-linked immunosorbent assay for diagnosis of canine visceral leishmaniasis (CVL). The assays used sera from known negative controls (n=30), clinically symptomatic (n=30) and oligosymptomatic (n=30) parasitologically proven infection (by microscopy). Aspirates of popliteal lymph node from infected canines were colleted to score parasitism and compared with the ELISA results. The study indicated that FML used in ELISA provided high sensitivity for detecting oligosymptomatic dogs (90%) and CTA showed greater sensitivity than FML for symptomatic canines (90%). In oligosymptomatic dogs, specificity was 100% for CTA-ELISA, but in symptomatic dogs, FML specificity was higher (96.7%) than CTA-ELISA (93.3%). A significant correlation was observed between the degree of parasitism and the results obtained in CTA-ELISA. Since no available antigen offers 100% specificity and sensitivity for CVL diagnosis, the choice of antigen used must depend on the aim of the investigation. 相似文献