全文获取类型
收费全文 | 9635篇 |
免费 | 633篇 |
国内免费 | 204篇 |
专业分类
林业 | 627篇 |
农学 | 538篇 |
基础科学 | 88篇 |
1676篇 | |
综合类 | 1419篇 |
农作物 | 541篇 |
水产渔业 | 761篇 |
畜牧兽医 | 3753篇 |
园艺 | 272篇 |
植物保护 | 797篇 |
出版年
2023年 | 76篇 |
2022年 | 102篇 |
2021年 | 210篇 |
2020年 | 233篇 |
2019年 | 277篇 |
2018年 | 306篇 |
2017年 | 291篇 |
2016年 | 310篇 |
2015年 | 238篇 |
2014年 | 317篇 |
2013年 | 464篇 |
2012年 | 561篇 |
2011年 | 647篇 |
2010年 | 433篇 |
2009年 | 395篇 |
2008年 | 565篇 |
2007年 | 567篇 |
2006年 | 477篇 |
2005年 | 446篇 |
2004年 | 395篇 |
2003年 | 466篇 |
2002年 | 478篇 |
2001年 | 355篇 |
2000年 | 214篇 |
1999年 | 184篇 |
1998年 | 68篇 |
1997年 | 60篇 |
1996年 | 52篇 |
1995年 | 61篇 |
1994年 | 61篇 |
1993年 | 48篇 |
1992年 | 65篇 |
1991年 | 58篇 |
1990年 | 71篇 |
1989年 | 63篇 |
1988年 | 48篇 |
1987年 | 44篇 |
1986年 | 42篇 |
1985年 | 43篇 |
1984年 | 66篇 |
1983年 | 34篇 |
1982年 | 34篇 |
1981年 | 29篇 |
1980年 | 29篇 |
1979年 | 32篇 |
1978年 | 34篇 |
1977年 | 31篇 |
1974年 | 43篇 |
1972年 | 33篇 |
1971年 | 43篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
61.
A 3‐year‐old Arabian mare presented with diarrhoea and depression. During hospitalisation, the mare developed septic thrombophlebitis associated with a jugular catheter. One week later, she developed secondary bilateral tarsocrural joint septic arthritis. Following surgical intervention and intensive medical therapy, the mare recovered successfully. The case highlights an unusual and previously unreported complication of septic thrombophlebitis. 相似文献
62.
63.
64.
Pedotransfer functions to assess adsorbed phosphate using iron oxide content and magnetic susceptibility in an Oxisol 下载免费PDF全文
L. A. Camargo J. Marques Jr. G. T. Pereira L. R. F. Alleoni A. S. R. de S. Bahia D. De B. Teixeira 《Soil Use and Management》2016,32(2):172-182
Adsorbed phosphate in soils can be chemically extracted; however, this process is both time‐consuming and not cost‐effective if large numbers of samples have to be analysed. Indirect assessment of adsorbed phosphate by pedotransfer functions (PTFs) can help optimize fertilizer strategies. This study aimed to evaluate the spatial variability of adsorbed phosphate (Pads), iron oxides and magnetic susceptibility (MS) in oxisols and to calibrate PTFs to predict Pads. A total of 308 soil samples were collected from Hapludox and Eutrudox soils formed from sandstone in Brazil. The contents of clay (196–607 g/kg), iron oxides (40–165 g/kg), MS (1.2–29 × 10?6 m3/kg) and Pads (327–842 mg/kg) were in the range of typical values for these highly weathered soils. This study showed that the attributes studied were spatially dependent. Geomorphic surfaces enabled understanding of spatial variability and helped to develop a more efficient sampling scheme to calibrate PTFs. Moreover, the adsorbed phosphate in these oxisols could be predicted by a PTF using iron oxides and MS as predictors. The MS attribute enabled the most accurate prediction (concordance coefficient = 0.95, root‐mean‐square error = 46 mg/kg and relative improvement in root‐mean‐square error = ?4.12) of spatial variability through PTF compared to other predictors. 相似文献
65.
66.
Gil Luypaert Johan Witters Johan Van Huylenbroeck Patrick De Clercq Jan De Riek Ellen De Keyser 《Euphytica》2017,213(10):227
A set of putative marker genes to study plant defense responses against Polyphagotarsonemus latus, a key pest in the production of Rhododendron simsii hybrids, was selected and validated. Genes belonged to the biosynthetic pathway of phytohormones jasmonic acid (JA) (RsLOX, RsAOS, RsAOC, RsOPR3 and RsJMT) and salicylic acid (SA) (RsPAL and RsICS). Furthermore, RsPPO, a putative marker gene for oxidative stress response was successfully cloned from R. simsii. A CTAB-based extraction protocol was optimized to assure excellent RNA quality for subsequent RT-qPCR analysis. The RT-qPCR protocol was extensively tested and RsRG7 and RsRG14 were selected as reference genes from a geNorm pilot study. Validation of the marker genes was done after application with elicitors [methyl jasmonate (MeJA), coronatine, β-aminobutyric acid and acibenzolar-Smethyl] or wounding. Both 100 μM MeJA and 0.1 μM coronatine had a significant effect on the expression of all marker genes. Foliar application of MeJA on the shoots resulted in a significantly earlier response when compared to root application and subsequent sampling of the shoots. Expression patterns after MeJA treatment were generally the same in six R. simsii genotypes: ‘Nordlicht’, ‘Elien’, ‘Aiko Pink’, ‘Michelle Marie’, ‘Mevrouw Gerard Kint’ and ‘Sachsenstern’. Wounding resulted in the same expression patterns as MeJA treatment except for RsJMT. None of the genotypes showed a significant induction of the latter gene 6 h upon wounding. Findings of these experiments indicated that the tolerant genotype ‘Elien’ has low basal expression levels of RsPPO. This might be the first step towards the breeding of mite-tolerant genotypes. 相似文献
67.
68.
We incorporated explanatory factors including stream habitat type and fish density into individual‐based models with dynamic connections among adjacent habitat units to infer dispersal behaviour of juvenile steelhead Oncorhynchus mykiss in a Great Lakes watershed. We used mark–recapture data and an inverse modelling approach to estimate daily probability of steelhead moving out of a habitat unit, P(move), according to four competing models. The models used included (i) a null model where all fish had equal movement probability; (ii) a habitat‐dependent model where P(move) depended on the habitat type; (iii) a density‐dependent model of P(move); and (iv) a model where P(move) depended on both density and habitat type. The habitat‐dependent model provided the most parsimonious fit to the observed data according to Akaike's information criteria (AICc). In the null model, P(move) averaged 0.70, whereas P(move) averaged 0.75 in pools, 0.68 in riffles and 0.73 in runs in the habitat‐dependent model. 相似文献
69.
Bravo Carlo Millo Christian Covelli Stefano Contin Marco De Nobili Maria 《Journal of Soils and Sediments》2020,20(2):1074-1086
Journal of Soils and Sediments - Humic acids (HA) have several environmental roles, but are particularly important in aquatic environments, being recognized as redox active natural organic matter... 相似文献
70.
浙江省商品有机肥中重金属含量变化趋势及风险管控对策 总被引:3,自引:1,他引:2