全文获取类型
收费全文 | 2032篇 |
免费 | 144篇 |
国内免费 | 4篇 |
专业分类
林业 | 54篇 |
农学 | 34篇 |
239篇 | |
综合类 | 497篇 |
农作物 | 63篇 |
水产渔业 | 108篇 |
畜牧兽医 | 1062篇 |
园艺 | 40篇 |
植物保护 | 83篇 |
出版年
2023年 | 17篇 |
2022年 | 14篇 |
2021年 | 58篇 |
2020年 | 67篇 |
2019年 | 58篇 |
2018年 | 52篇 |
2017年 | 61篇 |
2016年 | 54篇 |
2015年 | 54篇 |
2014年 | 61篇 |
2013年 | 86篇 |
2012年 | 141篇 |
2011年 | 163篇 |
2010年 | 81篇 |
2009年 | 61篇 |
2008年 | 143篇 |
2007年 | 163篇 |
2006年 | 119篇 |
2005年 | 161篇 |
2004年 | 112篇 |
2003年 | 132篇 |
2002年 | 127篇 |
2001年 | 14篇 |
1999年 | 8篇 |
1998年 | 20篇 |
1997年 | 9篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1994年 | 6篇 |
1993年 | 8篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1978年 | 3篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1972年 | 3篇 |
1965年 | 3篇 |
1963年 | 3篇 |
1956年 | 3篇 |
排序方式: 共有2180条查询结果,搜索用时 15 毫秒
971.
Marrero E Sánchez J de Armas E Escobar A Melchor G Abad MJ Bermejo P Villar AM Megías J Alcaraz MJ 《Fitoterapia》2006,77(4):313-315
The aqueous extract of Rhizophora mangle bark and its polyphenolic fractions showed remarkable in vitro antiinflammatory activity in a preliminary study. The low molecular weight fraction exhibited cyclooxygenase-2 inhibitory activity while the total aqueous extract and the low molecular weight fraction showed secretory phospholipase A(2) inhibitory activity. 相似文献
972.
973.
Cyclopia genistoides, normally used for the preparation of an herbal tea, honeybush, is a good source of the bio-active compounds mangiferin and hesperidin and is in demand for the preparation of xanthone-enriched extracts. Near-infrared spectroscopy (NIRS) was used to develop calibration models to predict the mangiferin and hesperidin contents of the dried green plant material. NIRS measurements of plant material and pure compounds were performed in diffuse reflectance mode. The calibration sets for mangiferin and hesperidin contents ranged from 0.7 to 7.21 and 0.64-4.80 g/100 g, respectively. Using independent validation, it was shown that the NIRS calibration models for the prediction of mangiferin (SEP=0.46 g/100 g; R2=0.74; and RPD=1.96) and hesperidin (SEP=0.38 g/100 g; R2=0.72; and RDP=1.90) contents of the dried plant material are adequate for screening purposes, based on RPD values. 相似文献
974.
Fragopoulou E Nomikos T Karantonis HC Apostolakis C Pliakis E Samiotaki M Panayotou G Antonopoulou S 《Journal of agricultural and food chemistry》2007,55(1):80-89
In recent years an effort has been made to isolate and identify biologically active compounds that are included in the Mediterranean diet. The existence of naturally occurring acetylated phenolics, as well as studies with synthetic ones, provide evidence that acetyl groups could be correlated with their biological activity. Platelet activating factor (PAF) is implicated in atherosclerosis, whereas its inhibitors seem to play a protective role against cardiovascular disease. The aim of this study was to examine the biological activity of resveratrol and tyrosol and their acetylated derivatives as inhibitors of PAF-induced washed rabbit platelet aggregation. Acetylation of resveratrol and tyrosol was performed, and separation was achieved by HPLC. Acetylated derivatives were identified by negative mass spectrometry. The data showed that tyrosol and its monoacetylated derivatives act as PAF inhibitors, whereas diacetylated derivatives induce platelet aggregation. Resveratrol and its mono- and triacetylated derivatives exert similar inhibitory activity, whereas the diacetylated ones are more potent inhibitors. In conclusion, acetylated phenolics exert the same or even higher antithrombotic activity compared to the biological activity of the initial one. 相似文献
975.
A simple, rapid, and low-cost gas chromatographic multiresidue method has been developed for the analysis of pesticide residues in raw and processed olives. This has been validated for 19 insecticides and triazine herbicides, covering a wide range of polarities. The method uses low-temperature precipitation to remove lipids and gives good cleanup for gas chromatography analysis with nitrogen phosphorus and electron capture detection. Recoveries are between 71 and 99%, with relative standard deviation values of 5-15%. 相似文献
976.
Dominic Standing Elizabeth M. Baggs Martin Wattenbach Pete Smith Ken Killham 《Biology and Fertility of Soils》2007,44(2):245-257
The scaling up of processes in the plant–soil–microbe system represents one of the greatest challenges facing environmental
scientists and yet is essential for sustainable land management worldwide. The latter encompasses, for example, the mitigation
of and adaptation to anthropogenic climate change, the bioremediation of industrially contaminated sites, catchment management
of human pathogens such as Escherichia coli O157 and integrated crop management on the farm. Scaling up is also essential for the regional and global biogeochemical
modelling that will inform policy-makers of the critical environmental factors driving climate change. Despite increasing
understanding of the links between gene expression and process on a microscale, there is still much progress to be made when
relating this to processes at the macroscale. In this paper, we explore the challenges this poses and examine key case studies
of successful up-scaling.
相似文献
Dominic StandingEmail: |
977.
978.
A case series of nine domestic cats with culture-confirmed Alternaria species infection is presented, with conclusions drawn regarding signalment, clinical signs, treatment and outcome. Middle aged neutered males were over-represented and all presented with cutaneous lesions involving the extremities (nose, pinnae and digits). Lesions were mainly slow-growing, poorly circumscribed nodules or plaques but some also presented as non-healing wounds. A combination of surgical excision with adjunctive medical therapy appeared to be the most successful treatment option but long courses of medical therapy were generally required and recurrence was common. 相似文献
979.
980.
Elizabeth A Leece BVSc CertVA Diplomate ECVAA MRCVS Nicolas M Girard† DVM CertVA MRCVS & Kieren Maddern BVSc MACVSc MRCVS 《Veterinary anaesthesia and analgesia》2009,36(5):480-484
Objective To evaluate the induction and maintenance of anaesthesia using alfaxalone following pre-anaesthetic medication with romifidine and butorphanol in ponies undergoing castration in the field.
Study design Prospective clinical study.
Animals Seventeen male ponies weighing 169 ± 29 kg.
Methods The ponies were sedated with romifidine and butorphanol intravenously (IV). Induction time was recorded following administration of alfaxalone 1 mg kg−1 and diazepam 0.02 mg kg−1 IV. If movement during surgery occurred, alfaxalone 0.2 mg kg−1 was administered IV. The quality of anaesthetic induction, and recovery were scored on a subjective scale of 1 (good) to 5 (poor). The number of attempts to attain sternal recumbency and standing, quality of recovery and times from induction to end of surgery, first head lift, sternal recumbency and standing were recorded.
Results Induction quality was good [median score (range) 1 (1–3)] with a mean ± SD time of 29 ± 6 seconds taken to achieve lateral recumbency. Ten ponies required incremental doses of alfaxalone during surgery. Mean times to the end of surgery, first head lift, sternal recumbency and standing were 26 ± 9 minutes, 31 ± 9 minutes, 33 ± 9 minutes and 34 ± 9 minutes respectively. The number of attempts to attain sternal recumbency was 1(1–1) and to attain standing was 1(1–2). Quality of recovery was good, with a recovery score of 1(1–2).
Conclusions and clinical relevance Alfaxalone provided smooth induction and recovery characteristics and was considered suitable for maintenance of anaesthesia for castration in ponies. 相似文献
Study design Prospective clinical study.
Animals Seventeen male ponies weighing 169 ± 29 kg.
Methods The ponies were sedated with romifidine and butorphanol intravenously (IV). Induction time was recorded following administration of alfaxalone 1 mg kg
Results Induction quality was good [median score (range) 1 (1–3)] with a mean ± SD time of 29 ± 6 seconds taken to achieve lateral recumbency. Ten ponies required incremental doses of alfaxalone during surgery. Mean times to the end of surgery, first head lift, sternal recumbency and standing were 26 ± 9 minutes, 31 ± 9 minutes, 33 ± 9 minutes and 34 ± 9 minutes respectively. The number of attempts to attain sternal recumbency was 1(1–1) and to attain standing was 1(1–2). Quality of recovery was good, with a recovery score of 1(1–2).
Conclusions and clinical relevance Alfaxalone provided smooth induction and recovery characteristics and was considered suitable for maintenance of anaesthesia for castration in ponies. 相似文献