全文获取类型
收费全文 | 234篇 |
免费 | 23篇 |
专业分类
林业 | 11篇 |
农学 | 11篇 |
32篇 | |
综合类 | 11篇 |
农作物 | 6篇 |
水产渔业 | 26篇 |
畜牧兽医 | 141篇 |
园艺 | 3篇 |
植物保护 | 16篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 8篇 |
2019年 | 8篇 |
2018年 | 4篇 |
2017年 | 8篇 |
2016年 | 17篇 |
2015年 | 5篇 |
2014年 | 5篇 |
2013年 | 16篇 |
2012年 | 9篇 |
2011年 | 16篇 |
2010年 | 8篇 |
2009年 | 13篇 |
2008年 | 8篇 |
2007年 | 11篇 |
2006年 | 11篇 |
2005年 | 11篇 |
2004年 | 5篇 |
2003年 | 6篇 |
2002年 | 6篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 4篇 |
1997年 | 9篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1974年 | 3篇 |
1973年 | 1篇 |
排序方式: 共有257条查询结果,搜索用时 640 毫秒
251.
Figueiredo HC Klesius PH Arias CR Evans J Shoemaker CA Pereira DJ Peixoto MT 《Journal of fish diseases》2005,28(4):199-204
Flavobacterium columnare is an important pathogen of freshwater fish, implicated in skin and gill disease, often causing high mortality. An outbreak of skin disease in fingerling and adult Nile tilapia, Oreochromis niloticus (L.), cultivated in a recirculation system, was investigated. Four strains were isolated and characterized by biochemical reactions, enzyme production, fatty acid profile and analysis of the 16S-23S rDNA intergenic spacer region. All strains were identified as F. columnare. Experimental infection assays with one of these strains (BZ-5-02) were conducted and pathogenicity (by intramuscular route) was demonstrated in Nile tilapia and channel catfish, Ictalurus punctatus (Rafinesque). This is the first report of characterization of Brazilian strains of F. columnare. 相似文献
252.
BACKGROUND: Pesticide residues remaining on food represent a potential risk to consumer's health. Determination of these pesticide residues involves tedious procedures of analysis with regard to time and laboratory work. Near‐infrared spectroscopy (NIRS) is a possible alternative to these methods. The aim of this research was to evaluate the ability of NIRS to classify two pesticides used for controlling apple fruit pests according to their concentration. Different solutions were prepared, based on the dose recommended by the pesticide producers for apple pest treatments. Spectra were acquired on a spectrophotometer from liquid samples belonging to these solutions. RESULTS: Calibration models were developed from liquid samples, following the soft independent modelling of class analogy (SIMCA) analysis method. These models classified between 99 and 100% of the validation samples belonging to different pesticide concentration solutions even at the maximum residue limit level of these products in apple fruit. CONCLUSIONS: NIRS technology shows a high potential for identifying pesticides in liquid samples, according to their concentration, at the levels required by the legislation. © 2012 Society of Chemical Industry 相似文献
253.
Otaiza-González Santiago N. Mary Verónica S. Arias Silvina L. Bertrand Lidwina Velez Pilar A. Rodriguez María G. Rubinstein Héctor R. Theumer Martín G. 《European journal of plant pathology / European Foundation for Plant Pathology》2022,162(1):203-219
European Journal of Plant Pathology - Fusarium graminearum and Zymoseptoria tritici cause economically important diseases of wheat. F. graminearum is one of the primary causal agents of Fusarium... 相似文献
254.
RW Graham EL Lundelius MA Graham EK Schroeder RS Toomey E Anderson AD Barnosky JA Burns CS Churcher DK Grayson RD Guthrie CR Harington GT Jefferson LD Martin HG McDonald RE Morlan HA Semken SD Webb L Werdelin MC Wilson 《Science (New York, N.Y.)》1996,272(5268):1601-1606
Analyses of fossil mammal faunas from 2945 localities in the United States demonstrate that the geographic ranges of individual species shifted at different times, in different directions, and at different rates in response to late Quaternary environmental fluctuations. The geographic pattern of faunal provinces was similar for the late Pleistocene and late Holocene, but differing environmental gradients resulted in dissimilar species composition for these biogeographic regions. Modern community patterns emerged only in the last few thousand years, and many late Pleistocene communities do not have modern analogs. Faunal heterogeneity was greater in the late Pleistocene. 相似文献
255.
Role of Gene Interactions in Hybrid Speciation: Evidence from Ancient and Experimental Hybrids 总被引:6,自引:0,他引:6
LH Rieseberg B Sinervo CR Linder MC Ungerer DM Arias 《Science (New York, N.Y.)》1996,272(5262):741-745
The origin of a new diploid species by means of hybridization requires the successful merger of differentiated parental species' genomes. To study this process, the genomic composition of three experimentally synthesized hybrid lineages was compared with that of an ancient hybrid species. The genomic composition of the synthesized and ancient hybrids was concordant (rs = 0.68, P < 0.0001), indicating that selection to a large extent governs hybrid species formation. Further, nonrandom rates of introgression and significant associations among unlinked markers in each of the three synthesized hybrid lineages imply that interactions between coadapted parental species' genes constrain the genomic composition of hybrid species. 相似文献
256.
PG Blanco D Arias A Rube JP Barrena Y Corrada C Gobello 《Reproduction in domestic animals》2009,44(S2):164-166
The aim of this study was to describe the changes in the resistance index (RI) and systolic/diastolic ratio ( S / D ) of the uterine arteries during mid-pregnancy abortion induction in the dog. Sixteen 30–35 day pregnant bitches were randomly assigned to either a pharmacological protocol to interrupt gestation (n = 8) or were used as untreated control group (n = 8). Doppler assessments of uterine arteries blood flow were carried out before the initiation of the protocol and then every other day up to abortion (treated group) or parturition (control group). All treated bitches aborted 6 ± 1.2 days after initiation of the treatment (while none of the non-treated bitches aborted). Pre-treatment RI and S / D did not differ between groups (p > 0.2) while average post-treatment indexes were (mean ± SD): 0.62 ± 0.1 vs 0.53 ± 0.1 (p < 0.01) and 2.96 ± 0.9 vs 2.23 ± 0.3 (p = 0.01), for the treated and non-treated group respectively. Correlations between days to abortion and RI or S / D were 0.75 (p < 0.01) and 0.79 (p < 0.01) and, −0.78 (p < 0.01) and −0.73 (p < 0.01) for the treated and non-treated groups respectively. In the treated group, correlations between serum progesterone (P4 ) concentrations and RI and S / D were −0.76 (p < 0.01) and −0.59 (p < 0.01) respectively. It is concluded that, during induction of abortion, RI and S / D of uterine arteries progressively increased while P4 decreased. 相似文献
257.
I. Pinaya B. Soto M. Arias F. Díaz‐Fierros 《Land Degradation \u0026amp; Development》2000,11(1):93-98
The efficiency of revegetation of burnt areas was put to the test with two different mixes of grasses, one comprising native species and the other, including Lolium multiflorum, sown by hand. Runoff generation and soil loss were studied over the first 20 months after the fire in seeded plots (two plots for each seed mix) and in an unseeded plot (considered as the control). The seeded plots showed a marked increase in vegetation, and 6 months after the fire ground cover was about 60 per cent in the plots seeded with native species. This ground cover value (considered to be the cover necessary for good protection against soil erosion) was reached in plots seeded with the commercial mix after 8 months and in the control plot after 14 months. Runoff volume was similar in all plots, but the soil erosion was reduced in both seeded plots by a factor of 6·5. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献