全文获取类型
收费全文 | 451篇 |
免费 | 29篇 |
专业分类
林业 | 17篇 |
农学 | 11篇 |
基础科学 | 1篇 |
94篇 | |
综合类 | 38篇 |
农作物 | 27篇 |
水产渔业 | 48篇 |
畜牧兽医 | 170篇 |
园艺 | 32篇 |
植物保护 | 42篇 |
出版年
2023年 | 7篇 |
2022年 | 5篇 |
2021年 | 8篇 |
2020年 | 17篇 |
2019年 | 19篇 |
2018年 | 13篇 |
2017年 | 16篇 |
2016年 | 22篇 |
2015年 | 17篇 |
2014年 | 11篇 |
2013年 | 23篇 |
2012年 | 30篇 |
2011年 | 37篇 |
2010年 | 26篇 |
2009年 | 15篇 |
2008年 | 29篇 |
2007年 | 35篇 |
2006年 | 30篇 |
2005年 | 25篇 |
2004年 | 18篇 |
2003年 | 21篇 |
2002年 | 18篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有480条查询结果,搜索用时 15 毫秒
91.
Effect of krill phospholipids versus soybean lecithin in microdiets for gilthead seabream (Sparus aurata) larvae on molecular markers of antioxidative metabolism and bone development 下载免费PDF全文
R. Saleh M.B. Betancor J. Roo V. Benítez‐Dorta M.J. Zamorano J.G. Bell M. Izquierdo 《Aquaculture Nutrition》2015,21(4):474-488
The objective of the present study was to compare the effectiveness of dietary marine phospholipids (MPL) obtained from krill and soybean lecithin (SBL) on the rearing performance and development of seabream (Sparus aurata) larvae. Larvae were fed from 16 to 44 day posthatching (dph) five formulated microdiets with three different levels (50, 70 and 90 g kg–1) of phospholipids (PL) obtained either from an MPL or from a SBL source. Larvae‐fed MPL show a higher survival, stress resistance and growth than those‐fed SBL, regardless the dietary PL level. Overall, the increase in MPL up to 70 g kg–1 total PL in diet was enough to improve larval gilthead seabream performance, whereas even the highest SBL inclusion level (90 g kg–1 PL) was not able to provide a similar success in larval growth or survival. Inclusion of SBL markedly increased the peroxidation risk as denoted by the higher TBARs in larvae, as well as a higher expression of CAT, GPX and SOD genes. Moreover, SBL tends to produce larvae with a lower number of mineralized vertebrae and a lower expression of osteocalcin, osteopontin and BMP4 genes. Finally, increasing dietary MPL or SBL lead to a better assimilation of polyunsaturated fatty acids in the larvae, n‐3HUFA (especially 20:5n‐3) or n‐6 fatty acids (especially 18:2n‐6), respectively. In conclusion, MPL had a higher effectiveness in promoting survival, growth and skeletal mineralization of gilthead seabream larvae in comparison with SBL. 相似文献
92.
Monica Puccini Lorenzo Guazzelli Andrea Luca Tasca Andrea Mezzetta Christian Silvio Pomelli 《Water, air, and soil pollution》2018,229(7):239
Thallium is an emerging contaminant, which can be retained in scale encrustation within the pipeline and then released to drinking water. It is included in the Priority Pollutant List of the U.S. EPA. In this study, a sample from the water pipeline of Pietrasanta (Italy), affected by the contamination of thallium, is characterized by SEM-EDS, TGA, and FT-IR. Fluorescence spectroscopy is then proposed as the optimal technique for the detection of the contaminant. The functionality of a previously reported fluorescent calix[4]arene-based chemosensor is verified first on a standard solution of thallium nitrate and then on the sample under investigation. The quenching of the fluorescence of the sensor during the complexation of thallium is confirmed, identifying an ON-OFF sensor with high sensitivity, able to detect concentrations as low as 10?6 M and with high potential of development for the in situ and fast monitoring of the pollutant in the water network. 相似文献
93.
Michael K. Rust Dong-Hwan Choe Erin Wilson-Rankin Kathleen Campbell John Kabashima Monica Dimson 《国际虫害防治杂志》2017,63(3):234-241
ABSTRACTThe western yellow jacket, Vespula penyslvanica (Saussare), is a serious seasonal pest of outdoor venues in the western United States. In the spring, queens and low numbers of workers were captured in heptyl-butyrate-baited traps until early July, when the number of foragers dramatically increased. Microsatellite data suggest that 18 colonies were actively foraging within the park in 2012. Foragers from 11 different colonies were collected at one trap site. In 2012 and 2013, sufficient numbers of foragers were not captured until early August when baiting trials were initiated. Baits were prepared with canned chicken mixed with fipronil for a final concentration of 0.025%. In 2012, a single baiting provided >96% reduction of foragers for at least two months. A second baiting late in the season provided >80% reductions. In 2013, one baiting trial resulted in a 74% and a 93% reduction. A bait acceptance study was conducted in 2014 to test a bait consisting of the juices from canned chicken and 0.025% fipronil incorporated into a hydrogel, and provided a much longer lasting bait in the field. 相似文献
94.
Ana C. Neves Juracy CB. Santos Júnior Rodrigo L. Marucio Monica Midon Stelio PL. Luna 《Veterinary anaesthesia and analgesia》2017,44(2):375-378
Objective
To evaluate three volumes of lidocaine for spermatic cord block to perform castration in cattle.Study design
Randomized blinded clinical study.Animals
Thirty mixed-breed Nellore cattle, aged 28–40 months and weighing 395 ± 21 (352–452) kg [mean ± standard deviation (range)].Methods
Cattle were restrained in a chute and allowed to stand without sedation. Three milliliters of 2% lidocaine without epinephrine were infiltrated subcutaneously at each site of scrotal incision in all animals. The animals were allocated to three groups of 10 animals each. Lidocaine 2% was injected into each spermatic cord using a volume of 2, 3 or 4 mL in groups A, B, or C, respectively. The total volumes of lidocaine used were 10, 12, and 14 mL in groups A, B, and C, respectively. The duration of surgery and the retraction of the testicle (scored as positive or negative according to retraction of the testicle) during the procedure were recorded. The data were statistically analyzed by one-way anova followed by Tukey’s and chi-square tests. Differences were considered significant when p < 0.05.Results
The mean surgical time was shorter in group C than in groups A and B (p < 0.001). In groups A, B and C, 90%, 60% and 10% of the animals showed retraction of the testicle, respectively. Fewer animals retracted the spermatic cord in group C than in group A (p = 0.002) and B (p = 0.02).Conclusions and clinical relevance
Optimal spermatic cord block was achieved by injection of 4 mL of 2% lidocaine 5 minutes before castration and following incisional infiltration of lidocaine, in adult cattle weighing about 400 kg. 相似文献95.
96.
The use of Contans (Coniothyrium minitans) in Belgian commercial lettuce greenhouses has so far not always fulfilled the expectations of growers. With the aim of improving the efficacy of control of lettuce drop (Sclerotinia sclerotiorum), Contans applied alone and Contans combined with Radix (Trichoderma asperellum and Trichoderma gamsii), Kraft pine lignin and Rovral was compared in three successive lettuce crops in a naturally infested greenhouse. At harvest of each crop, the effect on disease incidence, and the effect on viability and fungal infection of sclerotia buried prior to each crop was evaluated. Contans applied alone negatively affected the sclerotial viability, but did not reduce lettuce drop symptoms. The combination of Contans with Kraft pine lignin, on the other hand, reduced sclerotial viability and lettuce drop compared with the untreated control in the last crop. Furthermore, when Contans was combined with Kraft pine lignin, a higher number of infected sclerotia was observed compared with Contans applied alone. When Radix was added to the combination, there was no extra benefit for the control of lettuce drop. The combination of one Rovral application and Contans resulted in a significant control of lettuce drop together with a negative effect on sclerotial survival. Two Rovral applications, by contrast, reduced the ability of C. minitans to parasitize and kill the sclerotia. To conclude, integration of Contans with a reduced Rovral application and with Kraft pine lignin has potential to improve the control of lettuce drop in commercial greenhouses. 相似文献
97.
Martelli G Boccuzzi R Grandi M Mazzone G Zaghini G Sardi L 《Berliner und Münchener tier?rztliche Wochenschrift》2010,123(11-12):457-462
Eighty Italian heavy pigs having an initial body weight of about 75 kg were allotted to two experimental groups: a low light intensity group (LL), in which pigs received the lowest level of illumination mandatory in piggeries (40 lux) and a high light intensity group (HL), in which pigs were exposed to a higher level of illumination (80 lux). For both groups the light phase lasted 12 hours per day. Pigs were slaughtered at about 160 kg body weight. Light intensity showed to have no effects on the growth traits, carcass parameters or neutrophil-to-lymphocyte ratio of heavy. With the exception of drinking (more frequently observed among LL pigs; P < 0.01) and sternal recumbency (more frequently observed among pigs belonging to HL group; P < 0.01), the behavioural observations, carried out on 20 pigs per group, indicated that light intensity did not affect the main behavioural traits of pigs. Agonistic interactions were significantly higher (P < 0.05) among pigs receiving a lower level of illumination (40 lux; LL group) and pigs exposed to the higher level of illumination (80 lux; HL group) showed a tendency (P < 0.1) towards a higher proportion of tactile social interactions. Our results confirm that a proper illumination level can be included among environmental conditions having a positive effect in order to preserve swine welfare. 相似文献
98.
Rita Pernice Mario Parisi Italo Giordano Alfonso Pentangelo Giulia Graziani Monica Gallo Vincenzo Fogliano Alberto Ritieni 《Scientia Horticulturae》2010
Carotenoids and flavonoids are the main tomatoes antioxidants, having an important role for human health. This study investigates the effects of different water regime and of the industrial processing on the concentration of these compounds in tomato fruits and in tomato products. Two biotypes of Corbarini small tomatoes were cultivated in the Sarno valley (Salerno, Italy) using three different water regimes. A biochemical characterization of the fresh and of the corresponding canned products was performed. Results show that water regime influenced the antioxidant profile of tomato fruits, with marked differences between the two biotypes. Data obtained highlight that water regime markedly influenced the productivity and the quality of the tomatoes. Results also demonstrated that industrial process increased carotenoids content without causing a significant flavonoids degradation. 相似文献
99.
100.
Consequences of spatial heterogeneity for ecosystem services in changing forest landscapes: priorities for future research 总被引:2,自引:2,他引:0
Changes in key drivers (e.g., climate, disturbance regimes and land use) may affect the sustainability of forest landscapes and set the stage for increased tension among competing ecosystem services. We addressed two questions about a suite of supporting, regulating and provisioning ecosystem services in each of two well-studied forest landscapes in the western US: (1) How might the provision of ecosystem services change in the future given anticipated trajectories of climate, disturbance regimes, and land use? (2) What is the role of spatial heterogeneity in sustaining future ecosystem services? We determined that future changes in each region are likely to be distinct, but spatial heterogeneity (e.g., the amount and arrangement of surviving forest patches or legacy trees after disturbance) will be important in both landscapes for sustaining forest regeneration, primary production, carbon storage, natural hazard regulation, insect and pathogen regulation, timber production and wildlife habitat. The paper closes by highlighting five general priorities for future research. The science of landscape ecology has much to contribute toward understanding ecosystem services and how land management can enhance—or threaten—the sustainability of ecosystem services in changing landscapes. 相似文献