全文获取类型
收费全文 | 2972篇 |
免费 | 242篇 |
国内免费 | 4篇 |
专业分类
林业 | 138篇 |
农学 | 53篇 |
基础科学 | 10篇 |
343篇 | |
综合类 | 429篇 |
农作物 | 65篇 |
水产渔业 | 148篇 |
畜牧兽医 | 1779篇 |
园艺 | 72篇 |
植物保护 | 181篇 |
出版年
2023年 | 15篇 |
2022年 | 15篇 |
2021年 | 49篇 |
2020年 | 64篇 |
2019年 | 51篇 |
2018年 | 52篇 |
2017年 | 57篇 |
2016年 | 55篇 |
2015年 | 52篇 |
2014年 | 78篇 |
2013年 | 154篇 |
2012年 | 166篇 |
2011年 | 203篇 |
2010年 | 123篇 |
2009年 | 106篇 |
2008年 | 169篇 |
2007年 | 173篇 |
2006年 | 170篇 |
2005年 | 161篇 |
2004年 | 170篇 |
2003年 | 170篇 |
2002年 | 130篇 |
2001年 | 52篇 |
2000年 | 55篇 |
1999年 | 37篇 |
1998年 | 22篇 |
1997年 | 21篇 |
1996年 | 18篇 |
1995年 | 17篇 |
1994年 | 17篇 |
1993年 | 20篇 |
1992年 | 33篇 |
1991年 | 34篇 |
1990年 | 39篇 |
1989年 | 35篇 |
1988年 | 30篇 |
1987年 | 22篇 |
1986年 | 15篇 |
1985年 | 17篇 |
1984年 | 14篇 |
1983年 | 19篇 |
1979年 | 26篇 |
1978年 | 14篇 |
1977年 | 15篇 |
1974年 | 17篇 |
1973年 | 14篇 |
1972年 | 15篇 |
1971年 | 14篇 |
1970年 | 15篇 |
1969年 | 14篇 |
排序方式: 共有3218条查询结果,搜索用时 15 毫秒
121.
122.
Nancy E. Scott MS DVM DACVECC Thierry Francey Dr. med. vet. DACVIM Karl Jandrey DVM DACVECC 《Journal of Veterinary Emergency and Critical Care》2007,17(2):191-196
Objective: To describe a case of confirmed baclofen intoxication in a dog that was successfully treated with hemodialysis and hemoperfusion (HD/HP) and to report the serum baclofen kinetics. Case summary: A 2.5‐year‐old, 23 kg, spayed female Brittany Spaniel‐mix was treated after ingesting 21‐52 mg/kg of baclofen. The dog was comatose and was receiving manual ventilation at the time of presentation. Extracorporeal HD/HP was started 10 hours after admission. Within 3 hours of starting HD/HP the dog began initiating breaths and was extubated 18 hours after admission. Serial serum samples that were obtained during the first 24 hours of hospitalization were later analyzed for baclofen concentrations. The dog had elevated creatine phosphokinase and liver enzymes that correlated with an agitated recovery period. The dog had thrombocytopenia that resolved by 10 days after presentation. New or unique information provided: HD/HP shortened the baclofen serum elimination half‐life from 5 to 1.5 hours in the initial 2 hours of treatment. The intrinsic elimination rate constant (Kintr) for this dog was 0.138/hour and the total elimination rate constant (Ktot) during the first 2 hours of HD/HP treatment was 0.458/hour. In this dog, HD/HP was an effective method for rapidly decreasing serum baclofen concentration after an acute overdose. 相似文献
123.
Repetitive extragenic palindromic polymerase chain reaction (rep-PCR), sequencing of the 16S−23S rDNA internal transcribed spacer (ITS), biochemical and physiological tests, the Biolog microplate system, polyacrylamide gel electrophoresis (PAGE) of whole-cell proteins, and pathogenicity tests were used to characterize variability among xanthomonads isolated from pistachio trees suffering from bacterial dieback in four regions of Australia. ITS sequencing and rep-PCR revealed two distinct genotypes among the strains. The ITS sequencing suggested that the pistachio strains were closely related to Xanthomonas translucens pathovars, in particular X. translucens pv . poae . Results of physiological and biochemical tests, as well as Biolog microplate analysis and protein profiling, confirmed the existence of two groups. Furthermore, pathogenicity and host-range studies indicated that the two groups were biologically different. There was an association between the two groups and the geographical origin of the strains. 相似文献
124.
125.
Comparison of the Sensitivity of Landscape-fire-succession Models to Variation in Terrain, Fuel Pattern, Climate and Weather 总被引:1,自引:0,他引:1
Geoffrey J. Cary Robert E. Keane Robert H. Gardner Sandra Lavorel Mike D. Flannigan Ian D. Davies Chao Li James M. Lenihan T. Scott Rupp Florent Mouillot 《Landscape Ecology》2006,21(1):121-137
The purpose of this study was to compare the sensitivity of modelled area burned to environmental factors across a range of
independently-developed landscape-fire-succession models. The sensitivity of area burned to variation in four factors, namely
terrain (flat, undulating and mountainous), fuel pattern (finely and coarsely clumped), climate (observed, warmer & wetter,
and warmer & drier) and weather (year-to-year variability) was determined for four existing landscape-fire-succession models
(EMBYR, FIRESCAPE, LANDSUM and SEM-LAND) and a new model implemented in the LAMOS modelling shell (LAMOS(DS)). Sensitivity
was measured as the variance in area burned explained by each of the four factors, and all of the interactions amongst them,
in a standard generalised linear modelling analysis. Modelled area burned was most sensitive to climate and variation in weather,
with four models sensitive to each of these factors and three models sensitive to their interaction. Models generally exhibited
a trend of increasing area burned from observed, through warmer and wetter, to warmer and drier climates with a 23-fold increase
in area burned, on average, from the observed to the warmer, drier climate. Area burned was sensitive to terrain for FIRESCAPE
and fuel pattern for EMBYR. These results demonstrate that the models are generally more sensitive to variation in climate
and weather as compared with terrain complexity and fuel pattern, although the sensitivity to these latter factors in a small
number of models demonstrates the importance of representing key processes. The models that represented fire ignition and
spread in a relatively complex fashion were more sensitive to changes in all four factors because they explicitly simulate
the processes that link these factors to area burned.
The US Government's and the Canadian Government's right to retain a non-exclusive, royalty-free license is acknowledged 相似文献
126.
S.W. Scott M.T. Zimmerman Xin Ge D.J. MacKenzie 《European journal of plant pathology / European Foundation for Plant Pathology》1998,104(2):155-161
A complete sequence for the RNA 3 of Prunus necrotic ringspot virus (PNRSV) is described (Genbank Accession U57046). Primers from this sequence were used to amplify both the movement protein and coat protein genes of 3 other isolates of PNRSV originating from different host species and geographic locations. Comparisons of these sequences with those of other published sequences for PNRSV and the closely related apple mosaic virus (ApMV) showed that both the movement proteins and coat proteins of isolates of PNRSV are extensively conserved irrespective of either the original host or the geographic origin. The movement protein and coat protein of ApMV and PNRSV are sufficiently conserved to suggest that these two viruses may have evolved from a common ancestor. The amino acid sequence of the two coat proteins shows areas of similarity and difference that would explain the serological continuum reported to occur among isolates of these two viruses. Nevertheless, the movement protein and coat protein of the two viruses are sufficiently different so that ApMV and PNRSV should be considered to be distinct viruses. 相似文献
127.
Relationship between physiological factors and clinical pain in dogs scored using a numerical rating scale 总被引:1,自引:0,他引:1
L. L. Holton E. M. Scott † A. M. Nolan J. Reid E. Welsh 《The Journal of small animal practice》1998,39(10):469-474
A study was designed to investigate the association between heart rate, respiratory rate and pupil dilation and a subjective pain score allocated using a numerical rating scale (NRS). Four groups of dogs (n = 17 to 20 per group) were included: orthopaedic surgery cases, soft tissue surgery cases, dogs with medical conditions and healthy dogs. Each dog was examined by five veterinary surgeons within a four-hour period. When examining each dog, the observers recorded heart rate, respiratory rate, pupil dilation (present or absent) and a pain score using a NRS (range 0 to 10). For surgical cases, all study assessments were carried out between 21 and 27 hours following the end of surgery. The correlation coefficients between physiological parameters and NRS score were small but, depending on the analysis, were significant for heart rate and NRS score (P < 0·05). However, the size of the coefficient, 0·168, indicated that the relationship was not biologically significant. There was no association between respiratory rate and NRS score. Analysis of the relationship between NRS score and pupil dilation indicated that there was an association between this factor and pain, depending on the analysis. This was significant for the surgical groups (P < 0·05) but not for the other groups.
These findings indicate that heart rate and respiratory rate are not useful indicators of pain in hospitalised dogs. It is also unlikely that pupil dilation will be a useful tool in the assessment of pain. 相似文献
These findings indicate that heart rate and respiratory rate are not useful indicators of pain in hospitalised dogs. It is also unlikely that pupil dilation will be a useful tool in the assessment of pain. 相似文献
128.
Brian S. Dorr Loren W. Burger Scott C. Barras Kristina Casscles Godwin 《Journal of the World Aquaculture Society》2012,43(4):502-513
The Yazoo River Basin of Mississippi, USA, supports the largest concentration of hectares devoted to channel catfish, Ictalurus punctatus, aquaculture production in North America. The Yazoo Basin also supports large numbers of resident, wintering and migrating fish‐eating birds, with the Double‐crested Cormorant, Phalacrocorax auritus, implicated as the most serious depredating species. We used data from aerial surveys of numbers and distribution of cormorants in the Yazoo Basin and on commercial catfish ponds during winters (November–April) 2000–2001 and 2003–2004 to refine estimates of regional economic losses due to cormorant depredation. In both periods, the greatest monthly estimates of cormorant foraging occurred from 1 January to 31 March. Losses in terms of biomass, number, and dollar value were greater for foodfish ponds than fingerling ponds. Monthly weighted estimates of catfish consumed were 1775.3 and 1346.6 m.t. over winters 2000–2001 and 2003–2004, respectively. Total estimated losses for foodfish and fingerling ponds in 2000–2001 were $11.56 and $0.48 million, respectively, and in 2003–2004 were $5.22 and $0.40 million, respectively. Maximum dollar loss occurred during March in 2000–2001 and during February in 2003–2004. In this study, the volatility in variable production costs and nominal sales price, and distribution of cormorants on pond types and regionally were key factors in resulting economic loss estimates. 相似文献
129.
130.