首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   30篇
  免费   4篇
林业   4篇
农学   2篇
基础科学   1篇
  4篇
综合类   2篇
农作物   4篇
水产渔业   4篇
畜牧兽医   11篇
植物保护   2篇
  2020年   2篇
  2019年   1篇
  2018年   1篇
  2017年   1篇
  2016年   2篇
  2014年   2篇
  2013年   1篇
  2012年   2篇
  2011年   3篇
  2010年   2篇
  2009年   1篇
  2008年   3篇
  2007年   3篇
  2006年   1篇
  2004年   2篇
  2003年   2篇
  2002年   2篇
  1996年   1篇
  1983年   2篇
排序方式: 共有34条查询结果,搜索用时 16 毫秒
21.
Marine natural products have been the focus of discovery for new products of chemical and pharmacological interest. The aim of this study was to evaluate the antinociceptive activity of the methanolic (ME), acetate (AE), hexanic (HE) and chloroform (CE) extracts obtained from Caulerpa mexicana, and ME, CE and HE obtained from Caulerpa sertularioides. These marine algae are found all over the world, mainly in tropical regions. Models such as the writhing test, the hot plate test and formalin-induced nociception test were used to evaluate antinociceptive activity in laboratory mice. In the writhing test, all the extracts were administered orally at a concentration of 100 mg/kg, and induced high peripheral antinociceptive activity, with a reduction in the nociception induced by acetic acid above 65%. In the hot plate test, treatment with extracts from C. sertularioides (100 mg/kg, p.o.) did not significantly increase the latency of response, although the ME, AE and HE from C. mexicana showed activity in this model. This result suggests that these extracts exhibit antinociceptive activity. In the formalin test, it was observed that ME, AE and HE obtained from C. mexicana reduced the effects of formalin in both phases. On the other hand only CE from C. sertularioides induced significant inhibition of the nociceptive response in the first phase. To better assess the potential anti-inflammatory activity of the extracts, the carrageenan-induced peritonitis test was used to test Caulerpa spp. extracts on cell migration into the peritoneal cavity. In this assay, all extracts evaluated were able to significantly inhibit leukocyte migration into the peritoneal cavity in comparison with carrageenan. These data demonstrate that extracts from Caulerpa species elicit pronounced antinociceptive and anti-inflamatory activity against several nociception models. However, pharmacological and chemical studies are continuing in order to characterize the mechanism(s) responsible for the antinociceptive action and also to identify the active principles present in the Caulerpa species.  相似文献   
22.
In penicillin(pen), streptomycin(str), kanamycin(kan) and tetracycline(tet)-treated CBA/J adult mice, no difference was noticed as concerned spleen T “helper” (Th) cell activity, as studied by means of response to PHA of X-irradiated/whole T fraction cell mixtures in vitro. On the contrary, in erythromycin(erm), colistin(col) and chloramphenicol(chl)-treated groups, Th cell activity was significantly decreased. On the other hand, spleen T “suppressor” (Ts) cell activity (assayed by response to PHA of mixtures containing pre-incubated with Concanavalin A and whole T cells, respectively) was augmented in samples arising from chl-treated group. These results are also supported by experiments testing Th or Ts soluble factors, induced in spleen T cells belonging to each antibiotic-treated group and purified by affinity chromatography (Concanavalin A-Sepharose 4B columns). Thus, it was confirmed both Th cell deficiency in erm, col or chl-groups, and Ts cell augmentation in chl-group.

As regards spleen “natural cytotoxic” (NC) cell activity, as tested in a xenogeneic “target” cell substrate, a diminished cytotoxic capacity manifested chl-group-derived NC cells, possibly by richness in own “non-specific suppressor” (NSS) cells. NC cell samples in vitro supplemented with NSS cells arising from suckling mouse spleens and a lower cytotoxic activity, in a larger extent in chl-group-derived NC cells, as compared to other groups. The pre-incubation of control-group-NC cells with several antibiotic preparations in vitro was followed by decrease of the cytotoxic values in erm, col and chl-samples, suggesting a drug-induced NC receptor “masking”, that prevented “target” cell recognition in mice—II. In the case of NSS addition in vitro, as strong inhibition of the cytotoximity occurred in chl-treated NC cells derived from the control group, that proves a possible chloramphenicol-induced immunodepression by potentiation of NSS inhibitory effect on NC cells.

Based upon data from the present work, as well as from the previous work, the authors suggest a classification of several mechanisms by which the antibacterial antibiotics can act as immunosuppressive.  相似文献   

23.
The Ipojuca river, a river in Northeast Brazil extending from west to east, is situated in the semiarid interior and rainy coastal zone of Pernambuco state. The river basin covers an area of 3,514 km2, with a total river length of 215 km. The water flow regime is characterized by the annual change from dry to rainy season as well as periodically occurring dry cycles. Mean flow rates vary between 2 and 35 m3 s?1. The dominant impacts on water quality of the river are domestic sewage input in the upper catchment and sugar cane cultivation and processing in the lower catchment. Long-term monitoring data used to demonstrate the impact of sewage discharge on the river’s self-purification capacity indicated a severe change to the worse in the lower course. One reason is the use of stillage (wastewater from cane processing) for fertilization and irrigation (fertigation). Pathways of contamination have been identified by evaluating cultivation and processing techniques of a bio-alcohol factory with annexed sugar cane cultivation. The river’s main ecological problems are water heating, acidification, increased turbidity, oxygen imbalance, and increased coliform bacteria levels. Precipitation-related wash-off and wash-out causes significant contamination within one to two days after rainfall. The increase in coliform bacteria is a consequence of secondary contamination. To determine the impact of the sugar cane industry on the river, the Brazilian bio-alcohol program must be subject to a critical evaluation. Environmentally friendly sugar cane cultivation methods need to be developed, and sugar cane factories must use waste-reducing technologies and water cycling processes in order to protect the region’s water resources.  相似文献   
24.
Maintaining the numbers of wood mice and common voles at an acceptable economic level, especially during years of massive outbreaks, is a major challenge in plant protection. Efforts to reduce the negative effects of rodenticides on the environment, to improve the integrated pest control system, and to minimize risks for human and animal health require investigation of the potentials of cellulose, as a natural product, and sodium selenite as rodenticides. The present study was conducted to determine the sensitivity of these rodent species to bromadiolone (a.i. 0.005 %), sodium selenite (a.i. 0.1 and 0.05 %), and cellulose (a.i. 45 %) baits. All experiments were done using no-choice and choice feeding trials. A low acceptance of cellulose baits was found in the choice feeding trial, and the time of first deaths indicate that stress and hunger increase the death rate in both species. The taste had a negative impact on the acceptability of baits containing sodium selenite. Low bait acceptance of cellulose and sodium selenite resulted in lower mortality of both species. The acquired results indicate that bromadiolone remains a more effective solution than cellulose and sodium selenite for control of wood mice and common voles.  相似文献   
25.
  1. Incidental capture by fisheries is one of the principal threats to sea turtles. This study analysed spatial and temporal patterns of sea turtle bycatch, and estimated the direct initial mortality rate of these animals, in the industrial double‐rig‐bottom trawl fishery in south‐eastern Brazil. This is also the first attempt to relate bycatch/at‐sea mortality in bottom trawling to stranded turtles found along the adjacent coast.
  2. The fishery was monitored from October 2015 to April 2018 through data collected voluntarily by the captains of eight industrial double‐rig trawlers. Two hundred and one sea turtles were captured during 9362 tows (43,657.52 trawling hours), resulting in a catch per unit effort (CPUE) of 0.0025 ± 0.0032 turtles h?1 with a standard net of 30.5 m headrope, with no significant difference between the estimated CPUEs for licensed shrimp and demersal fish trawlers.
  3. Caretta caretta (52.24%) and Lepidochelys olivacea (38.81%) were the most frequently captured species. According to Generalized Linear Models, C. caretta bycatch was significantly higher during winter, at lower latitudes (?24° to ?23°) and higher longitudes (?42° to ?40°), while the L. olivacea bycatch was significantly higher at higher latitudes (?23° to ?21°). The direct initial mortality rate of sea turtles in the shrimp trawlers was 7.65 ± 3.85%. However, none of the dead individuals subsequently released with plastic tags (n = 10) were found stranded on the coast. Mortality was not significantly related to the depth or duration of the trawling.
  4. The results of this study suggest the need for improvements to the current management of the bottom trawl fishery in Brazil, moving from a species‐based to a spatial and seasonal‐based approach. There is also a need to develop turtle excluder devices adapted to local fishing conditions.
  相似文献   
26.
The experiment was conducted with the aim of determining the attractability and palatability of liquid protein hydrolysates for Nile tilapia. Five experimental diets were formulated containing 5% inclusion of fishmeal (FPE; positive control), 5% inclusion of liquid protein hydrolysate of porcine mucosa (PHM), 5% inclusion of liquid protein hydrolysate of poultry (PHF), 5% inclusion of liquid fish oil (OPE) and a diet without fishmeal (negative control). Five juveniles (2.51 ± 0.13 g) were distributed in 10 L tanks, and the animals were fed five times a day, with a previous draw being made of the offered diets. The same amount of pellets was offered and the following feeding behaviours were evaluated with the aid of three‐minute footages per feeding: time to capture first pellet, number of rejections, number of approaches without capturing the pellet and number of consumed pellets. None of the observed parameters displayed significant differences (p > .05), and all diets presented negative palatability indexes in comparison to FPE. The SPE diet provided a attractability and palatability index of 6.17%, while OPE index was 2.87%, PHM 2.82% and PHF 2.74%. Both PHF and PHM reduced the final consumption of pellets in comparison to FPE in approximately 28% and 20%, respectively, although it did not present significant values.  相似文献   
27.
28.
The physical, molecular, and functional properties of corn, cassava, and yam starches were related to the film properties of these starches. Corn, cassava, and yam starches contained 25%, 19%, and 30% amylose, respectively. Amylose from yam starch showed the smallest molecular weight among the starches and amylopectin from corn starch the smallest molecular weight. Cassava starch presented a higher amylopectin content, and its gels and films were less strong, more transparent, and more flexible than corn and yam films. Plasticized films of the three starches were more flexible, with a higher strain and lower stress at break when the glycerol content increased. Unplasticized films were brittle and had water vapor permeability values ranging from 6.75 x 10(-10) to 8.33 x 10(-10) g m(-1) s(-1) Pa(-1). These values decreased when the glycerol content reached 20 g/100 g of starch because a more compact structure was formed. Then, at a glycerol content of 40 g/100 g of starch, the WVP increased because the film matrixes became less dense.  相似文献   
29.
The marine environment is an extraordinary reservoir of bioactive natural products, many of which exhibit chemical and structural features not found in terrestrial natural products. In this regard, the aim of this study was to investigate the possible antinociceptive and anti-inflammatory activities of a crude methanolic extract of the red alga Bryothamnion triquetrum (BT-MeOH) in murine models. Groups of Swiss mice of both sexes (25–30 g) were used throughout the experiments. The potential antinociceptive of BT-MeOH was evaluated by means of the following tests: acetic acid-induced writhing, hot-plate test and glutamate- and formalin-induced nociception. The anti-inflammatory activity of BT-MeOH was investigated using the zymosan A-induced peritonitis test. The tests were conducted using 100 mg/kg (p.o.) BT-MeOH, 33.3 mg/kg (p.o.) dipyrone, 35.7 mg/kg (p.o.) indomethacin and 5.7 mg/kg (s.c.) morphine. The extract and all standard drugs were administered 40 min before the nociceptive/inflammatory stimulus. In the acetic acid-induced writhing test, BT-MeOH and dipyrone inhibited the nociceptive response by 55.9% (22.2 ± 2.0 writhings; p < 0.01) and 80.9% (9.6 ± 2.1 writhings; p < 0.01). In the hot-plate test, BT-MeOH did not increase the latency time of the animals in the time evaluated. In addition, BT-MeOH inhibited glutamate-induced nociception by 50.1%. While BT-MeOH did not inhibit the neurogenic phase in formalin-induced nociception, the inflammatory phase was inhibited by 53.1% (66.8 ± 14.2 s; p < 0.01). Indomethacin inhibited the inflammatory phase by 60.2% (56.8 ± 8.7 s; p < 0.01). In the zymosan-induced peritonitis test, BT-MeOH inhibited 55.6% (6.6 ± 0.2 × 106 leukocytes/mL; p < 0.01) of leukocyte migration, while indomethacin inhibited 78.1% (3.2 ± 0.1 × 106 leukocytes/mL; p < 0.01). Based on the results obtained in this study, we conclude that BT-MeOH has peripheral antinociceptive and anti-inflammatory activities. However, more studies need to be conducted to confirm these properties.  相似文献   
30.
As detailed in the Association of Schools of Public Health / Association of American Veterinary Medical Colleges 2007 Joint Symposium on Veterinary Public Health, veterinary public health (VPH) can no longer be viewed as a unique sub-specialty of veterinary medicine. Rather, its practice pervades nearly every aspect of the veterinary profession, regardless of whether the practitioner is engaged in small-animal, large-animal, research, corporate, or military practice. In congruence with the practice of VPH, the teaching of VPH should also pervade nearly every aspect of veterinary education. Accordingly, at Western University of Health Sciences, College of Veterinary Medicine (WU-CVM), public health is not simply taught as an individual course but, rather, is interwoven into almost every aspect of the curriculum, continually emphasizing the relevance of this discipline to the practice of veterinary medicine. This article outlines the teaching philosophy of WU-CVM, provides an overview of the curriculum, and describes the integral nature of public health throughout all four years of the educational program.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号