全文获取类型
收费全文 | 218篇 |
免费 | 21篇 |
专业分类
239篇 |
出版年
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 5篇 |
2013年 | 14篇 |
2012年 | 9篇 |
2011年 | 8篇 |
2010年 | 5篇 |
2009年 | 9篇 |
2008年 | 6篇 |
2007年 | 10篇 |
2006年 | 9篇 |
2005年 | 9篇 |
2004年 | 7篇 |
2003年 | 9篇 |
2002年 | 11篇 |
2001年 | 6篇 |
2000年 | 7篇 |
1999年 | 6篇 |
1998年 | 2篇 |
1997年 | 7篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 12篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 14篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1949年 | 1篇 |
排序方式: 共有239条查询结果,搜索用时 15 毫秒
11.
P Puska J Tuomilehto J Salonen L Neittaanm?ki J Maki J Virtamo A Nissinen K Koskela T Takalo 《BMJ (Clinical research ed.)》1979,2(6199):1173-1178
A comprehensive community programme to control cardiovascular diseases (CVD) in North Karelia, Finland, was carried out during 1972-7. The central intermediate objective of the programme was to reduce the prevalence of smoking, the serum cholesterol concentration, and raised blood-pressure values among the population of the area. The effect was evaluated by examining independent representative population samples in 1972 and 1977 in both the county of North Karelia and a matched control county. Over 10 000 subjects were studied each time, the participation rate being around 90%. The decrease that occurred in the risk factors, especially in men, was in general greater in North Karelia compared with the control county. When a multiple logistic function was used for the three risk factors an overall mean net reduction of 17% among men and 12% among women was observed in the estimated risk for coronary heart disease in North Karelia. This community programme effectively reduced the levels of the three main risk factors for CVD in the population, and thus mortality and morbidity from CVD should fall. This is assessed in further studies. 相似文献
12.
Felde Vivian A. Flantua Suzette G. A. Jenks Cathy R. Benito Blas M. de Beaulieu Jacques-Louis Kuneš Petr Magri Donatella Nalepka Dorota Risebrobakken Bjørg ter Braak Cajo J. F. Allen Judy R. M. Granoszewski Wojciech Helmens Karin F. Huntley Brian Kondratienė Ona Kalniņa Laimdota Kupryjanowicz Mirosława Malkiewicz Małgorzata Milner Alice M. Nita Małgorzata Noryśkiewicz Bożena Pidek Irena A. Reille Maurice Salonen J. Sakari Šeirienė Vaida Winter Hanna Tzedakis Polychronis C. Birks H. John B. 《Vegetation History and Archaeobotany》2020,29(1):101-109
Vegetation History and Archaeobotany - The Eemian interglacial represents a natural experiment on how past vegetation with negligible human impact responded to amplified temperature changes... 相似文献
13.
Two pot experiments were conducted to examine three-level interactions between host plants, mycorrhizal fungi and parasitic
plants. In a greenhouse experiment, Poa annua plants were grown in the presence or absence of an AM fungus (either Glomus lamellosum V43a or G. mosseae BEG29) and in the presence or absence of a root hemiparasitic plant (Odontites vulgaris). In a laboratory experiment, mycorrhizal infection (Glomus claroideum BEG31) of Trifolium pratense host plants (mycorrhizal versus non-mycorrhizal) was combined with hemiparasite infection (Rhinanthus serotinus) of the host (parasitized versus non-parasitized). Infection with the two species of Glomus had no significant effect on the growth of P. annua, while hemiparasite infection caused a significant reduction in host biomass. Mycorrhizal status of P. annua hosts (i.e. presence/absence of AM fungus) affected neither the biomass nor the number of flowers produced by the attached O. vulgaris plants. Infection with G. claroideum BEG31 greatly increased the biomass of T. pratense, but hemiparasite infection had no effect. The hemiparasitic R. serotinus plants attached to mycorrhizal hosts had higher biomass and produced more flowers than plants growing with non-mycorrhizal
hosts. Roots of T. pratense were colonized by the AM fungus to an extent independent of the presence or absence of the hemiparasite. Our results confirm
earlier findings that the mycorrhizal status of a host plant can affect the performance of an attached root hemiparasite.
However, improvement of the performance of the parasitic plant following attachment to a mycorrhizal host depends on the extent
to which the AM fungi is able to enhance the growth of the host.
Accepted: 23 February 2001 相似文献
14.
The importance of bacterial utilization of released phytoplankton photosynthate in two humic forest lakes in southern Finland 总被引:6,自引:0,他引:6
Bacterial utilization of photosynthetically fixed dissolved organic carbon (PDOC) released from natural phytoplankton assemblages was studied in two small, extremely humic, forest lakes in southern Finland. Bacterial activity (measured as uptake of 14 C-glucose) and phytoplankton photosynthesis (measured as light uptake of 14 CO2 ) could be most effectively separated using Nuclepore filters of pore size 1–2 μm. Released PDOC was 10–67% of total phytoplankton carbon fixation during in situ experiments, and represented about 0.1% of total DOC. Net uptake of PDOC by bacteria was found to be about 20% during 24 hour laboratory incubations, although about 40% of PDOC present at the start of an experiment could be utilized by bacteria during a 24 hour period. PDOC does not provide a quantitatively important substrate supply for bacterial respiration in humic forest lakes. 相似文献
15.
G. Marcoullis R. Gräsbeck E.-M. Salonen 《Biochimica et Biophysica Acta (BBA)/General Subjects》1977,497(3):663-672
Pig ileal mucosa was found to bind about 240 ng vitamin B12/g and to contain two vitamin B12-binding proteins. One was highly active in the Schilling test, behaved immunologically as intrinsic factor and was responsible for about half of the total vitamin B12-binding capacity. The other binder was identified as cobalophilin (R-protein). Immunochemical purification of these proteins from pig ileum and pylorus was performed and the molecular characteristics (sedimentation and diffusion coefficients, Strokes radii, frictional ratios and molecular weights) of their vitamin B12 complexes were estimated. Isoelectric focusing revealed differences between the ileal and pyloric intrinsic factors but not between the cobalophilins. The mean isoelectric points of the pyloric and ileal intrinsic factors were pH 5.79 and 5.30, respectively, whereas the corresponding figures for the cobalophilins were 4.13 and 4.10. 相似文献
16.
17.
Kolmeder CA de Been M Nikkilä J Ritamo I Mättö J Valmu L Salojärvi J Palva A Salonen A de Vos WM 《PloS one》2012,7(1):e29913
The human intestinal tract is colonized by microbial communities that show a subject-specific composition and a high-level temporal stability in healthy adults. To determine whether this is reflected at the functional level, we compared the faecal metaproteomes of healthy subjects over time using a novel high-throughput approach based on denaturing polyacrylamide gel electrophoresis and liquid chromatography-tandem mass spectrometry. The developed robust metaproteomics workflow and identification pipeline was used to study the composition and temporal stability of the intestinal metaproteome using faecal samples collected from 3 healthy subjects over a period of six to twelve months. The same samples were also subjected to DNA extraction and analysed for their microbial composition and diversity using the Human Intestinal Tract Chip, a validated phylogenetic microarray. Using metagenome and single genome sequence data out of the thousands of mass spectra generated per sample, approximately 1,000 peptides per sample were identified. Our results indicate that the faecal metaproteome is subject-specific and stable during a one-year period. A stable common core of approximately 1,000 proteins could be recognized in each of the subjects, indicating a common functional core that is mainly involved in carbohydrate transport and degradation. Additionally, a variety of surface proteins could be identified, including potential microbes-host interacting components such as flagellins and pili. Altogether, we observed a highly comparable subject-specific clustering of the metaproteomic and phylogenetic profiles, indicating that the distinct microbial activity is reflected by the individual composition. 相似文献
18.
19.
Bela M Arosalo Marja Raekallio Minna Rajamäki Elina Holopainen Tuulia Kastevaara Hanna Salonen Satu Sankari 《Acta veterinaria Scandinavica》2007,49(1):4
Background
The aim of the study was to investigate urine matrix metalloproteinase (MMP-2 and -9) activity, alkaline phosphatase/creatinine (U-AP/Cr) and gamma-glutamyl-transpeptidase/creatinine (U-GGT/Cr) ratios, glucose concentration, and urine protein/creatinine (U-Prot/Cr) ratio and to compare data with plasma MMP-2 and -9 activity, cystatin-C and creatinine concentrations in colic horses and healthy controls. Horses with surgical colic (n = 5) were compared to healthy stallions (n = 7) that came for castration. Blood and urine samples were collected. MMP gelatinolytic activity was measured by zymography. 相似文献20.
S. A. Everson J. W. Lynch M. A. Chesney G. A. Kaplan D. E. Goldberg S. B. Shade R. D. Cohen R. Salonen J. T. Salonen 《BMJ (Clinical research ed.)》1997,314(7080):553-558
OBJECTIVE: To examine the combined influence of workplace demands and changes in blood pressure induced by stress on the progression of carotid atherosclerosis. DESIGN: Population based follow up study of unestablished as well as traditional risk factors for carotid atherosclerosis, ischaemic heart disease, and other outcomes. SETTING: Eastern Finland. SUBJECTS: 591 men aged 42-60 who were fully employed at baseline and had complete data on the measures of carotid atherosclerosis, job demands, blood pressure reactivity, and covariates. MAIN OUTCOME MEASURES: Change in ultrasonographically assessed intima-media thickness of the right and left common carotid arteries from baseline to 4 year follow up. RESULTS: Significant interactions between workplace demands and stress induced reactivity were observed for all measures of progression (P < 0.04). Men with large changes in systolic blood pressure (20 mm Hg or greater) in anticipation of a maximal exercise test and with high job demands had 10-40% greater progression of mean (0.138 v 0.123 mm) and maximum (0.320 v 0.261 mm) intima-media thickness and plaque height (0.347 v 0.264) than men who were less reactive and had fewer job demands. Similar results were obtained after excluding men with prevalent ischaemic heart disease at baseline. Findings were strongest among men with at least 20% stenosis or non-stenotic plaque at baseline. In this subgroup reactive men with high job demands had more than 46% greater atherosclerotic progression than the others. Adjustment for atherosclerotic risk factors did not alter the results. CONCLUSIONS: Men who showed stress induced blood pressure reactivity and who reported high job demands experienced the greatest atherosclerotic progression, showing the association between dispositional risk characteristics and contextual determinants of disease and suggesting that behaviourally evoked cardiovascular reactivity may have a role in atherogenesis. 相似文献