全文获取类型
收费全文 | 1018篇 |
免费 | 84篇 |
专业分类
1102篇 |
出版年
2024年 | 2篇 |
2023年 | 11篇 |
2022年 | 18篇 |
2021年 | 45篇 |
2020年 | 27篇 |
2019年 | 26篇 |
2018年 | 30篇 |
2017年 | 33篇 |
2016年 | 36篇 |
2015年 | 70篇 |
2014年 | 71篇 |
2013年 | 66篇 |
2012年 | 112篇 |
2011年 | 78篇 |
2010年 | 51篇 |
2009年 | 44篇 |
2008年 | 58篇 |
2007年 | 57篇 |
2006年 | 37篇 |
2005年 | 33篇 |
2004年 | 41篇 |
2003年 | 40篇 |
2002年 | 33篇 |
2001年 | 6篇 |
2000年 | 2篇 |
1999年 | 8篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 8篇 |
1994年 | 3篇 |
1993年 | 9篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1967年 | 1篇 |
1965年 | 2篇 |
排序方式: 共有1102条查询结果,搜索用时 0 毫秒
91.
Jonas G. Barlind Linda K. Buckett Sharon G. Crosby Öjvind Davidsson Hans Emtenäs Anne Ertan Ulrik Jurva Malin Lemurell Pablo Morentin Gutierrez Karolina Nilsson Gavin O’Mahony Annika U. Petersson Alma Redzic Fredrik Wågberg Zhong-Qing Yuan 《Bioorganic & medicinal chemistry letters》2013,23(9):2721-2726
[Acyl CoA]monoacylglycerol acyltransferase 2 (MGAT2) is of interest as a target for therapeutic treatment of diabetes, obesity and other diseases which together constitute the metabolic syndrome. In this Letter we report our discovery and optimisation of a novel series of MGAT2 inhibitors. The development of the SAR of the series and a detailed discussion around some key parameters monitored and addressed during the lead generation phase will be given. The in vivo results from an oral lipid tolerance test (OLTT) using the MGAT2 inhibitor (S)-10, shows a significant reduction (68% inhibition relative to na?ve, p <0.01) in plasma triacylglycerol (TAG) concentration. 相似文献
92.
93.
Ulrike Taylor Holm Zerbe Hans-Martin Seyfert Detlef Rath Ulrich Baulain Kathrin Friederike Annika Langner Hans-Joachim Schuberth 《Animal reproduction science》2009,115(1-4):279-289
Early endometrial cytokine responses after exposure to various inseminate components were investigated for a better understanding of the immunological reactions occurring in the porcine uterus after insemination. Baseline values were established for the mRNA concentrations of GM-CSF, IL-6, IL-10, CXCL8 (interleukin-8), Tumour Necrosis Factor α (TNF-α), TGF-β, cyclooxygenase-2 (COX-2) and arachidonate 5-lipooxygenase (ALOX-5) in periovulatory uterine endometrial tissue using quantitative RT-PCR. Synchronized gilts were inseminated with spermatozoa diluted either in the semen extender Androhep™ or seminal plasma. Uterine infusions of media without spermatozoa were used as controls. Three hours after insemination sows were slaughtered and the expression of the above mentioned cytokines was measured in uterine epithelial cells. Simultaneously, the influx of polymorphonuclear neutrophilic (PMN) granulocytes into the uterus was quantified. Compared to baseline values seminal plasma (SP) and Androhep™ (AH) respectively, if used alone, caused a significant increase in mRNA concentrations of IL-10 (SP: 1.5-fold), TGF-β (AH: 1.5-fold), CXCL8 (AH: 7.1-fold), TNF-α (AH: 1.9-fold) and COX-2 (AH: 7-fold). Surprisingly, in the presence of spermatozoa, none of the tested cytokines revealed mRNA concentrations higher than baseline values. The number of immigrated, intra-luminal PMN correlated only with mRNA concentrations of CXCL8 in presence of Androhep™ (r = 0.51). None of the other cytokines tested seemed to be involved in the regulation of neutrophil recruitment. However, the most interesting result was the sperm-induced down-regulation in the expression of TNF-α, TGF-β, IL-10, CXCL8 and COX-2 to mRNA concentration levels similar to or even below baseline values. In conclusion the results show that CXCL8 contributes significantly to uterine PMN recruitment and indicate a so far underestimated role of porcine spermatozoa in the general regulation of the uterine post-mating inflammatory response. 相似文献
94.
95.
In order to investigate the impact of high oxygen and carbon dioxide concentrations, Escherichia coli was grown in batch cultivations where the air supply was enriched with either oxygen or carbon dioxide. The effect of elevated concentrations of oxygen and carbon dioxide on stochiometric and kinetic constants was studied this way. The maximum growth rate was significantly reduced, the production of acetic acid and the biomass yield coefficient on glucose increased in cultures with carbon dioxide enriched air, compared to reference cultivations and cultivations with oxygen enriched air. The application of oxygen enriched air was studied in high cell density cultivations of Escherichia coli. Two production processes were chosen to investigate the impact of oxygen enrichment. Biomass concentration, specific growth rate, yield coefficient, respiration, mixed acid fermentation products and the product yield and quality for the recombinant product were investigated. First, a process for the production of biomass was investigated. Exponential growth could proceed for a longer time and higher growth rates could be maintained with oxygen enriched air supply. However, a higher specific oxygen consumption rate per glucose was measured after the start of the oxygen enrichment, indicating higher maintenance and consequently the growth rate and yield coefficient decreased drastically in the end of the process. Second, a process for the production of recombinant human growth hormone (rhGH) was investigated. Although the glucose feed rate and all medium components were doubled, the amount of produced biomass could only be increased by 77% when oxygen enriched air (40% oxygen) supply was applied. This was due to a decreased yield coefficient of biomass per glucose. The total amount of produced product was decreased by almost 50% compared to the control, although less proteolytically degraded variants were produced. 相似文献
96.
Witold Wachowiak Annika Perry Kevin Donnelly Stephen Cavers 《Ecology and evolution》2018,8(1):655-666
Closely related taxa occupying different environments are valuable systems for studying evolution. In this study, we examined differences in early phenology (bud set, bud burst) and early growth in a common garden trial of closely related pine species: Pinus sylvestris, P. mugo, and P. uncinata. Seeds for the trial were sourced from populations across the ranges of each species in Europe. Over first 4 years of development, clear differences were observed between species, while the most significant intraspecific differentiation was observed among plants from P. sylvestris populations from continental European locations. Trait differences within P. sylvestris were highly correlated with altitude and latitude of the site of origin. Meanwhile, P. mugo populations from the Carpathians had the earliest bud set and bud flush compared to other populations of the species. Overall, populations from the P. mugo complex from heterogeneous mountain environments and P. sylvestris from the Scottish Highlands showed the highest within‐population variation for the focal traits. Although the three species have been shown to be genetically highly similar, this study reveals large differences in key adaptive traits both among and within species. 相似文献
97.
Lena Bj?rck Simon Capewell Martin O’Flaherty Georgios Lappas Kathleen Bennett Annika Rosengren 《PloS one》2015,10(5)
BackgroundThe relative importance of risk factor reduction in healthy people (primary prevention) versus that in patients with coronary heart disease (secondary prevention) has been debated. We aimed to quantify the contribution of the two.MethodologyWe used the previously validated IMPACT model to estimate contributions from primary prevention (reducing risk factors in the population, particularly smoking, cholesterol and systolic blood pressure) and from secondary prevention (reducing risk factors in coronary heart disease patients) in the Swedish population.ConclusionsThe largest effects on mortality came from primary prevention, giving markedly larger mortality reductions than secondary prevention. 相似文献
98.
The plant‐specific CDKB1‐CYCB1 complex mediates homologous recombination repair in Arabidopsis 下载免费PDF全文
99.
Initial design and physical characterization of a polymeric device for osmosis‐driven delayed burst delivery of vaccines 下载免费PDF全文
100.
Angeliki Pournara Maria Kippler Teresa Holmlund Rebecca Ceder Roland Grafström Marie Vahter Karin Broberg Annika E. Wallberg 《Cell biology and toxicology》2016,32(4):275-284
Arsenic, an established carcinogen and toxicant, occurs in drinking water and food and affects millions of people worldwide. Arsenic appears to interfere with gene expression through epigenetic processes, such as DNA methylation and post-translational histone modifications. We investigated the effects of arsenic on histone residues in vivo as well as in vitro. Analysis of H3K9Ac and H3K9me3 in CD4+ and CD8+ sorted blood cells from individuals exposed to arsenic through drinking water in the Argentinean Andes showed a significant decrease in global H3K9me3 in CD4+ cells, but not CD8+ cells, with increasing arsenic exposure. In vitro studies of inorganic arsenic-treated T lymphocytes (Jurkat and CCRF-CEM, 0.1, 1, and 100 μg/L) showed arsenic-related modifications of H3K9Ac and changes in the levels of the histone deacetylating enzyme HDAC2 at very low arsenic concentrations. Further, in vitro exposure of kidney HEK293 cells to arsenic (1 and 5 μM) altered the protein levels of PCNA and DNMT1, parts of a gene expression repressor complex, as well as MAML1. MAML1 co-localized and interacted with components of this complex in HEK293 cells, and in silico studies indicated that MAML1 expression correlate with HDAC2 and DNMT1 expression in kidney cells. In conclusion, our data suggest that arsenic exposure may lead to changes in the global levels of H3K9me3 and H3K9Ac in lymphocytes. Also, we show that arsenic exposure affects the expression of PCNA and DNMT1—proteins that are part of a gene expression silencing complex. 相似文献