全文获取类型
收费全文 | 324篇 |
免费 | 12篇 |
国内免费 | 2篇 |
专业分类
林业 | 12篇 |
农学 | 23篇 |
基础科学 | 5篇 |
88篇 | |
综合类 | 41篇 |
农作物 | 23篇 |
水产渔业 | 12篇 |
畜牧兽医 | 91篇 |
园艺 | 11篇 |
植物保护 | 32篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 7篇 |
2020年 | 11篇 |
2019年 | 11篇 |
2018年 | 8篇 |
2017年 | 6篇 |
2016年 | 15篇 |
2015年 | 6篇 |
2014年 | 9篇 |
2013年 | 12篇 |
2012年 | 18篇 |
2011年 | 35篇 |
2010年 | 16篇 |
2009年 | 22篇 |
2008年 | 18篇 |
2007年 | 22篇 |
2006年 | 19篇 |
2005年 | 24篇 |
2004年 | 13篇 |
2003年 | 10篇 |
2002年 | 18篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 5篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1971年 | 2篇 |
1955年 | 1篇 |
1863年 | 1篇 |
排序方式: 共有338条查询结果,搜索用时 31 毫秒
121.
Fusarium root rot (FRR) is a major disease of common bean worldwide. Knowledge of the inheritance of resistance to FRR would be important
in devising strategies to breed resistant varieties. Therefore, a 12 × 12 full diallel mating scheme with reciprocal crosses
was performed to generate 132 F1 progenies, which were then advanced to the F3. The progenies were evaluated for resistance to FRR under green house conditions in Uganda. General combining ability (GCA)
effects were highly significant (P ≤ 0.01) for disease scores. Specific combining ability effects were not significant (P > 0.05) in the F1, but were highly significant (P < 0.01) in the F3 generation. These results indicate that resistance to FRR was governed by genes with additive effects in combination with
genes with non-additive effects. Reciprocal differences were also significant (P = 0.01) at F1 and F3, primarily reflecting a large influence of maternal effects in both these generations. In fact, susceptible parents did not
differ significantly (P > 0.05) for disease scores when used as paternal parents in the F3, but differed strongly as maternal parents (P = 0.0002). Generally, the progenies were distinctly more resistant when the resistant parent was used as the female in crosses,
especially as observed in the F3. The maternal effects were strong in the F3 generation, suggesting a complex form of cytoplasmic–genetic interaction. The non-maternal reciprocal effects in the F3 were significant (P < 0.05) in both the resistant × resistant diallel, and in the resistant × susceptible crosses. Mid-parent heterosis (MPH)
occurred in most crosses, with average heterosis approximately equal in each of the three generations, indicating that epistasis
was probably more influential than dominance of individual genes. Gene-number formulas indicated that several genes were involved
in resistant × susceptible crosses. Among resistant × resistant crosses, many produced continuous distributions of F1 progeny scores, suggesting polygenic inheritance, while bi-modal distributions were characteristic of the F3 distributions, and fit expected ratios for two or three loci segregating in each cross. Dominant forms of epistasis favoring
resistance were strongly indicated. Parent–offspring heritability estimates were moderate. Overall, the results indicate that
resistant parents contain a number of different resistance genes that can be combined with the expectation of producing strong
and durable resistance. The lines MLB-49-89A, MLB-48-89, RWR719 and Vuninkingi, with large and negative GCA effects, contributed
high levels of resistance in crosses and would be recommended for use in breeding programs. 相似文献
122.
Sansone Umberto Belli Maria Fernandez José A. Comans Rob N. J. Jeran Zvonka Cavolo Fabio Barbizzi Sabrina De Zorzi Paolo Jacimovic Radojko 《Water, air, and soil pollution》2002,141(1-4):313-324
Aquarium experiments were performed to quantify the inorganic fraction of suspended particles deposited on the external surface of aquatic biota. The mass of suspended particles retained on the surfaces of microalgae growing on submerged substrates and the algal biomass were determined by comparing the scandium content of suspended material with that in algal communities. Scandium, a predominantly soil-associated trace element, has been used as a ‘tracer’ for the inorganic component of suspended particles, because this element is geologically ubiquitous in soils, and it is recognized that it cannot cross natural membranes of plants and other organisms. The algal biomass determined using the scandium content was compared with biomass values calculated using phytopigments as estimates of periphyton biomass. The results indicate that the suspended particle mass adhering to the external periphyton surface may accounted for up to 55% of the total mass collected on submerged artificial substrates. 相似文献
123.
Rob Cleven Yusuf Nur Petra Krystek Gerard Van Den Berg 《Water, air, and soil pollution》2005,165(1-4):249-263
Although a number of metal speciation methods are nowadays available, most water quality regulations are based on total metal concentrations. One of the main reasons for the ignorance of speciation is the lack of methods with potentiality for monitoring. Conditions that have to be met by such speciation methods are: simple performance, robust and sufficiently accurate. In this study the potential for monitoring purposes of Diffusive Gradients in Thin films (DGT) is investigated as part of a European project for sensor development for routine prediction of metal biouptake in natural waters. Performance characteristics of DGT have been assessed in experiments under controlled laboratory conditions and during in situ application over 4–9 months under different hydrological conditions in the rivers Meuse and Rhine. Results have been worked out for Cu, Ni and Pb. The study shows that DGT has sufficient potential as a robust tool in routine monitoring to observe trends in water quality. However, it appears that during in situ application of DGT the measurement uncertainty of the results is much larger than under laboratory conditions. The increase in measurement uncertainties will partially be due to uncertainties in some as constant considered factors in the calculation of the DGT concentration. For Cu and Ni, the average values for the reproducibility in the rivers Meuse and Rhine appeared to be 28% and 17%, respectively, whereas under laboratory conditions the reproducibilities for both metals were better than 10%. In the speciation of Cu, Ni and Pb in the rivers Meuse and Rhine, the labile fraction, determined using DGT, decreased in the series Ni, Cu, Pb. The ratio of the non-labile and labile fractions of the metals appeared to decrease with increasing content of Dissolved Organic Carbon (DOC). 相似文献
124.
Caboni P Sarais G Melis M Cabras M Cabras P 《Journal of agricultural and food chemistry》2004,52(22):6700-6702
A method for determining residues of the new reduced-risk pesticide acequinocyl and its deacetylated derivative hydroxyacequinocyl on fruits and vegetables (grapes, lemons, pears, and tomatoes) by HPLC is described. The pesticides were extracted from the fruits and vegetables with hexane and ethyl acetate solution (1:1, v/v), determined by HPLC-DAD at 250 nm and confirmed by LC/MS. No cleanup was necessary. This method is characterized by recoveries (0.01-4 mg/kg) > 77%, while the coefficient of variation was determined to be less than 11%. The limit of quantitation for both acequinocyl and hydroxyacequinocyl was 0.01 mg/kg for all matrixes. 相似文献
125.
Akkerdaas JH Wensing M Knulst AC Stephan O Hefle SL Aalberse RC van Ree R 《Journal of agricultural and food chemistry》2004,52(25):7726-7731
Contamination of food products with pepsin resistant allergens is generally believed to be a serious threat to patients with severe food allergy. A sandwich type enzyme-linked immunosorbent assay (ELISA) was developed to measure pepsin resistant hazelnut protein in food products. Capturing and detecting rabbit antibodies were raised against pepsin-digested hazelnut and untreated hazelnut protein, respectively. The assay showed a detection limit of 0.7 ng/mL hazelnut protein or <1 microg hazelnut in 1 g food matrix and a maximum of 0.034% cross-reactivity (peanut). Chocolate samples spiked with 0.5-100 microg hazelnut/g chocolate showed a mean recovery of 97.3%. In 9/12 food products labeled "may contain nuts", hazelnut was detected between 1.2 and 417 microg hazelnut/g food. It can be concluded that the application of antibodies directed to pepsin-digested food extracts in ELISA can facilitate specific detection of stable proteins that have the highest potential of inducing severe food anaphylaxis. 相似文献
126.
Rivier P Furneaux R Viguier E 《The Canadian veterinary journal. La revue veterinaire canadienne》2011,52(1):62-66
This prospective study describes a simple method of combining laparoscopic ovariectomy and laparoscopic-assisted prophylactic gastropexy and determines the duration of surgery, complications, and long-term outcome including prevention of gastric dilatation-volvulus (GDV). Laparoscopic ovariectomy and laparoscopic-assisted gastropexy were performed on 26 sexually intact female dogs susceptible to GDV. The mean surgery time was 60.8 ± 12.4 min. No GDV episode was seen during the study period (mean follow-up: 5.2 ± 1.4 y). All dogs had an intact gastropexy attachment assessed by ultrasonography at 1 y. Post-operative complications were minor and owners were satisfied with the procedure. Combined laparoscopic ovariectomy and laparoscopic- assisted gastropexy appears to be a successful and low morbidity alternative procedure to both ovariectomy/ovariohysterectomy and gastropexy via open ventral-midline laparotomy. 相似文献
127.
128.
129.
Davis R Jayappa H Abdelmagid OY Armstrong R Sweeney D Lehr C 《Veterinary therapeutics : research in applied veterinary medicine》2007,8(1):32-40
Healthy dogs with low antibody titer to Bordetella bronchiseptica were vaccinated intranasally with an avirulent live vaccine, subcutaneously with an antigen extract vaccine, or subcutaneously and intranasally with a placebo. Intranasally vaccinated dogs developed B. bronchiseptica-specific IgA titers in nasal secretions that remained at high levels until the end of the study; dogs vaccinated subcutaneously with the antigen extract or placebo did not develop measurable antigen-specific IgA titers in nasal secretions. Dogs were challenged with virulent live B. bronchiseptica 63 days after vaccination. Intranasally vaccinated dogs had significantly lower cough scores (P < or =.0058) and shed significantly fewer challenge organisms (P <.0001) than dogs in either of the other groups. Cough scores of subcutaneously vaccinated dogs were not significantly different from placebo-vaccinated dogs. 相似文献
130.