全文获取类型
收费全文 | 202篇 |
免费 | 4篇 |
专业分类
林业 | 13篇 |
农学 | 3篇 |
26篇 | |
综合类 | 25篇 |
农作物 | 8篇 |
水产渔业 | 7篇 |
畜牧兽医 | 99篇 |
园艺 | 1篇 |
植物保护 | 24篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 6篇 |
2015年 | 2篇 |
2014年 | 4篇 |
2013年 | 9篇 |
2012年 | 10篇 |
2011年 | 10篇 |
2010年 | 7篇 |
2009年 | 5篇 |
2008年 | 8篇 |
2007年 | 15篇 |
2006年 | 8篇 |
2005年 | 7篇 |
2004年 | 10篇 |
2003年 | 12篇 |
2002年 | 14篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 6篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 6篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1973年 | 2篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1969年 | 6篇 |
1968年 | 4篇 |
1967年 | 7篇 |
1963年 | 1篇 |
1954年 | 2篇 |
1940年 | 1篇 |
1938年 | 2篇 |
1937年 | 1篇 |
排序方式: 共有206条查询结果,搜索用时 15 毫秒
181.
Germain Jean Magloire Ketcha Wanda Georg Kretzschmar Dieudonn Njamen Maurice Tagatsing Fotsing Emmanuel Yankep Günter Vollmer 《Fitoterapia》2010,81(8):1232-1238
In the present study, we investigated whether griffonianone C (Griff C), extracted from root bark of Millettia griffoniana, changes the expression of several estrogen-responsive genes in the vena cava of ovariectomised rats. For this purpose, we subcutaneously administered Griff C (2, 10, or 20 mg/kg/d BW), 17β-estradiol (E2: 10 μg/kg/d BW) as positive control, and a vehicle control respectively for three days. Relative expression levels of estrogen receptor α (ERα), progesterone receptor (PR), cyclooxygenase2 (Cox-2), vascular endothelial growth factor (VEGF), VEGF-receptor 2, angiotensin converting enzyme (ACE), endothelial NO synthase (eNOS), proliferating cell nuclear antigen (PCNA) and Ki67 mRNA extracted from the vena cava of these rats were quantified by real-time PCR. Results showed that Griff C up-regulated the expression of PR, ACE, ERα, VEGF, VEGFR2 and Ki67. However, the results of Cox-2, PCNA, and eNOS expression did not reach significance in the E2 and Griff C treated samples. These results show that griffonianone C regulated a few of the analysed genes in a similar fashion than estradiol; however, others showed a different pattern. This suggests that some of the biological effects attributed to M. griffoniana are mediated via ER pathway others may be mediated via other pathways. 相似文献
182.
Establishment patterns of woody species in low intensity-grazed pastures after the cessation of intensive agricultural use 总被引:1,自引:0,他引:1
Low intensity grazing with large herbivores is increasingly used to steer the development of mosaic landscapes (including wood-pastures) and woodland expansion on former agricultural land. We studied the establishment and early growth pattern of woody species in grasslands (formerly used for high intensity summer cattle grazing) in which a low intensity-grazing regime was set up between 4 and 11 years ago. We tested whether the developing vegetation patches, consisting of tall herbs and scrub, influenced this pattern. Further, we investigated if increased susceptibility to trampling disturbance by large herbivores on wet soils in floodplains influenced sapling establishment.Formerly intensively used grasslands were studied at six sites, four in floodplains and two in interfluvial zones on nutrient rich, heavy soils. In total, we sampled 141 plots with grassland, tall herb or scrub vegetation and recorded individuals of established tree and shrub species, their height, diameter, browsing damage and distance to potential seed sources. In the floodplains, we recorded soil disturbance by large herbivores (hoofprints) in wet and moist soils.Sapling frequencies, with Fraxinus excelsior as the most common species (>50% of all individuals), were two to three times higher in tall herb and scrub patches compared to grassland. Only the spiny Crataegus monogyna established in higher frequencies in grassland plots. In floodplains, we found two to three times more established woody saplings in wet tall herb plots, compared to moist and wet grassland plots and moist tall herb plots.Browsing reduced sapling height in grassland and tall herb patches. Only in scrub patches did average height (±2.5 m) reach above the browse line. We found 30–70% less browsing damage to saplings in scrub compared to damage in grassland and tall herb plots. In particular, damage to the apical shoot was strongly reduced.Our findings show that tree establishment occurs in spatial association with non-grassland patches that offer protection against browsing. Fast growing spiny shrubs like Rubus sp. offer protection for palatable saplings, allowing establishment and growing out beyond the browse line. Alternatively, increased establishment occurs in wet tall herb patches, where soil disturbance by moderate trampling favours germination and, subsequently, saplings are protected at least temporarily against browsing by unpalatable tall herbs. 相似文献
183.
A large variety of unique N-atom containing compounds (alkaloids) without terrestrial counterparts, have been isolated from marine invertebrates, mainly sponges and ascidians. Many of these compounds display interesting biological activities. In this report we present studies on nitrogenous compounds, isolated by our group during the last few years, from Indo-Pacific sponges, one ascidian and one gorgonian. The major part of the review deals with metabolites from the Madagascar sponge Fascaplysinopsis sp., namely, four groups of secondary metabolites, the salarins, tulearins, taumycins and tausalarins. 相似文献
184.
Liméa Léticia Bocage Bruno Arquet Rémy Mahieu Maurice Alexandre Gisele 《Tropical animal health and production》2010,42(3):507-514
Carcass data base of 164 Creole male goats was used in order to provide factual data on the carcass conformation. Standardised
procedures of carcass measuring and cutting were followed. The European official grid of light lamb is implemented for meat
goat in the French West Indies and included five levels. Weights of carcass, cuts and tissues, quality scores and linear measurements
were analysed. Feeding system, age at slaughter and weight were taken into account for statistical analysis. There were significant
differences among carcass conformation classes (CC) for many traits except for the fat score, leg length and compactness ratio
(carcass width on length): 2.2, 34.5 cm and 0.30 on average, respectively. The values of chilled carcass weight and yield
and the carcass linear measurements steadily increased until conformation class 4 or 5: 6.7 to 11.2 kg, 49% to 55% and 52.4
to 58.0 cm carcass length. For the weights of carcass cuts, significant differences appeared between two groups: classes 1
and 2 vs. classes 3, 4 and 5. Regardless of the carcass weight, the distribution of prime cuts remained similar. The indices
calculated on a weight basis (kg/cm), either for the carcass or the leg, increased significantly (P < 0.01): with 54% and 63% difference between the two extreme classes, respectively. The muscle, bone and fat proportions
in the shoulder did not vary between CC with 0.72, 0.22 and 0.06, respectively. Corresponding traits in leg were 0.74, 0.23
and 0.03; the last two were different (P < 0.05) from class 1 to class 5. The muscle/bone ratios calculated either in shoulder or in leg ranged from 3.1 to 3.6 (P > 0.05). 相似文献
185.
François Rineau Jean-Paul Maurice Claude Nys Hubert Voiry Jean Garbaye 《Annals of Forest Science》2010,67(1):110-110
186.
187.
Changes in the relative sizes of the carboxylic absorption bands in the infrared spectra (near 1730 and 1610 cm?1) of adsorbents before and after treatment with paraquat (1,1′-dimethyl-4,4′-bipyridylium dichloride) showed that ion exchange is the predominant mechanism for adsorption of the bipyridyl by H+- ion saturated preparations of a humic acid from an organic soil, by two hydroquinone polymers and by two carboxylic ion-exchange resins. Attempts to relate the extents of saturation (with adsorbate) of the exchange sites with the optical densities of the infrared bands were unsuccessful because of deviations from Beer's Law. Ultraviolet spectroscopy failed to provide evidence for charge transfer mechanisms in paraquat-humic acid complexes in aqueous systems. 相似文献
188.
1. Two experiments were conducted to evaluate the use of naked oats (NO) in layer diets. In experiment 1 the use of NO supplemented with minerals, vitamins and lysine was examined. In experiment 2 layers were fed equicaloric and isonitrogenous diets containing 0-66% NO. 2. Layers fed ground NO supplemented with minerals, vitamins and lysine for 6 weeks exhibited a significant depression in food intake, egg production, egg weight and shell strength. 3. Substitution of NO at 20-66% resulted in performance comparable to that of birds fed a maize-soyabean meal diet for 12 weeks. Food intake was reduced in the first week of the experiment in birds fed diets with NO; thereafter, treatment effects were not detected. Yolk colour index progressively decreased as dietary inclusion of NO increased. 4. It is concluded that naked oats can be used at levels up to 66% in layer diets to replace all or part of the maize and part of the soyabean meal without any reduction in performance. 相似文献
189.
Maurice KT 《The Canadian veterinary journal. La revue veterinaire canadienne》2005,46(7):644-646
An 8-year-old mare showed stallion-like behavior and aggressiveness. A granulosa-theca cell tumor was tentatively diagnosed based on history, transrectal palpation, and ultrasonography, and surgically removed. Serological levels of testosterone and inhibin were elevated. Histopathological examination confirmed the diagnosis. The mare recovered and by day 45 could be turned out with other horses. 相似文献
190.
1. An experiment was conducted with two strains of layers to ascertain whether the reduction in eggshell strength occurring at the end of the production cycle is the result of reduced ascorbic acid biosynthesis. 2. Hens producing strong and weak eggshells were identified within each strain and egg production, egg weight, per cent shell, shell surface density, plasma, adrenal and hepatic ascorbic acid and renal L-gulonolactone oxidase activity were measured. 3. The strains differed in ascorbic acid synthesis, as measured by L-gulonolactone oxidase activity, and tissue ascorbic acid concentration. 4. Comparison of results from birds producing eggs of similar weight but markedly different in shell strength detected neither a shell strength group x strain interaction nor an effect of shell strength group on plasma and hepatic ascorbic acid and activity of L-gulonolactone oxidase. 5. The results did not support the hypothesis that tissue ascorbate and ascorbic acid biosynthesis are reduced in old hens producing weak eggshells. 相似文献