全文获取类型
收费全文 | 6040篇 |
免费 | 246篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 150篇 |
综合类 | 13篇 |
化学工业 | 1511篇 |
金属工艺 | 134篇 |
机械仪表 | 119篇 |
建筑科学 | 442篇 |
矿业工程 | 11篇 |
能源动力 | 133篇 |
轻工业 | 827篇 |
水利工程 | 37篇 |
石油天然气 | 13篇 |
无线电 | 325篇 |
一般工业技术 | 1011篇 |
冶金工业 | 753篇 |
原子能技术 | 61篇 |
自动化技术 | 753篇 |
出版年
2022年 | 48篇 |
2021年 | 78篇 |
2020年 | 60篇 |
2019年 | 64篇 |
2018年 | 74篇 |
2017年 | 93篇 |
2016年 | 123篇 |
2015年 | 145篇 |
2014年 | 163篇 |
2013年 | 266篇 |
2012年 | 242篇 |
2011年 | 256篇 |
2010年 | 218篇 |
2009年 | 240篇 |
2008年 | 236篇 |
2007年 | 271篇 |
2006年 | 211篇 |
2005年 | 217篇 |
2004年 | 197篇 |
2003年 | 138篇 |
2002年 | 148篇 |
2001年 | 119篇 |
2000年 | 107篇 |
1999年 | 97篇 |
1998年 | 118篇 |
1997年 | 105篇 |
1996年 | 101篇 |
1995年 | 91篇 |
1994年 | 64篇 |
1993年 | 89篇 |
1992年 | 83篇 |
1991年 | 58篇 |
1990年 | 69篇 |
1989年 | 67篇 |
1988年 | 45篇 |
1987年 | 75篇 |
1986年 | 62篇 |
1985年 | 81篇 |
1984年 | 71篇 |
1983年 | 62篇 |
1982年 | 66篇 |
1981年 | 71篇 |
1980年 | 68篇 |
1979年 | 69篇 |
1978年 | 53篇 |
1977年 | 57篇 |
1976年 | 64篇 |
1975年 | 59篇 |
1974年 | 67篇 |
1973年 | 50篇 |
排序方式: 共有6293条查询结果,搜索用时 31 毫秒
991.
992.
Hans Jagusch Tim U. H. Baumeister Prof. Dr. Georg Pohnert 《Chembiochem : a European journal of chemical biology》2020,21(17):2419-2424
Oxylipins constitute a family of oxidized fatty acids, that are well known as tissue hormones in mammals. They contribute to inflammation and its resolution. The major classes of these lipid mediators are inflammatory prostaglandins (PGs) and leukotrienes (LTs) as well as pro-resolving resolvins (Rvs). Understanding their biosynthetic pathways and modes of action is important for anti-inflammatory interventions. Besides mammals, marine algae also biosynthesize mammalian-like oxylipins and thus offer new opportunities for oxylipin research. They provide prolific sources for these compounds and offer unique opportunities to study alternative biosynthetic pathways to the well-known lipid mediators. Herein, we discuss recent findings on the biosynthesis of oxylipins in mammals and algae including an alternative pathway to prostaglandin E2, a novel pathway to a precursor of leukotriene B4, and the production of resolvins in algae. We evaluate the pharmacological potential of the algal metabolites with implications in health and disease. 相似文献
993.
994.
995.
Maximilian Michel Sandro Cocuzza Martin Biendl Frank Peifer Sebastian Hans Yvonne Methner Friedrich Pehl Werner Back Fritz Jacob Mathias Hutzler 《Journal of the Institute of Brewing》2020,126(4):354-361
Beer spoiling lactic acid bacteria are a major reason for quality complaints in breweries around the world. Spoilage by a variety of these bacteria can result in haze, sediment, slime, off-flavours and acidity. As these bacteria occur frequently in the brewing environment, using certain hop products that inhibit the growth of these spoilers could be a solution to prevent problems. To investigate the impact of seven different hop compounds (α-acids, iso-α-acids, tetrahydro-iso-α-acids, rho-iso-α-acids, xanthohumol, iso-xanthohumol and humulinones) on the growth of six major beer spoilage bacteria (Lactobacillus brevis. L. backi, L. coryniformis, L. lindneri, L. buchneri, Pediococcus damnosous), two concentrations (10 and 25 mg/L) of each hop substance were added to unhopped beer. The potential growth of the spoilage bacteria was investigated over 56 consecutive days. A comparison of the results shows a strong inhibition of growth of all spoilage bacteria at 25 mg/L of tetrahydro-iso-α-acids closely followed by α-acids as the second most inhibitory substance. The results showed a high resistance of L. brevis to all hop compounds as well as an inhibition of L. coryniformis and L. buchneri at low concentrations of most hop components. In comparison with the control sample, L. lindneri showed increased growth in the presence of some hop compounds (rho-iso-α-acids, xanthohumol, iso-xanthohumol, humulinones). © 2020 The Authors. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling 相似文献
996.
Philip Hans Franses 《控制论与系统》2020,51(8):746-756
Abstract This paper examines economic growth in 52 African countries for 1961–2016 and seeks to find if there is common growth. As all African countries have their particular features, concerning climate, harvest, industry, size, politics, and infrastructure, and more, it seems best to rely on a non-parametric method. Dynamic Time Warping is such a convenient method, also as it allows leads and lags across countries to vary over time, and as it can easily be incorporated into a clustering technique. Five clusters are found, two of which concern Equatorial Guinea and Botswana, and the three other clusters have common growth rates of about 0, 2 and 4 over more than five decades. 相似文献
997.
998.
Sebastian Granitzer Raimund Widhalm Martin Forsthuber Isabella Ellinger Gernot Desoye Markus Hengstschlger Harald Zeisler Hans Salzer Claudia Gundacker 《International journal of molecular sciences》2021,22(4)
The placental barrier can protect the fetus from contact with harmful substances. The potent neurotoxin methylmercury (MeHg), however, is very efficiently transported across the placenta. Our previous data suggested that L-type amino acid transporter (LAT)1 is involved in placental MeHg uptake, accepting MeHg-L-cysteine conjugates as substrate due to structural similarity to methionine. The aim of the present study was to investigate the antioxidant defense of placental cells to MeHg exposure and the role of LAT1 in this response. When trophoblast-derived HTR-8/SVneo cells were LAT1 depleted by siRNA-mediated knockdown, they accumulated less MeHg. However, they were more susceptible to MeHg-induced toxicity. This was evidenced in decreased cell viability at a usually noncytotoxic concentration of 0.03 µM MeHg (~6 µg/L). Treatment with ≥0.3 µM MeHg increased cytotoxicity, apoptosis rate, and oxidative stress of HTR-8/SVneo cells. These effects were enhanced under LAT1 knockdown. Reduced cell number was seen when MeHg-exposed cells were cultured in medium low in cysteine, a constituent of the tripeptide glutathione (GSH). Because LAT1-deficient HTR-8/SVneo cells have lower GSH levels than control cells (independent of MeHg treatment), we conclude that LAT1 is essential for de novo synthesis of GSH, required to counteract oxidative stress. Genetic predisposition to decreased LAT1 function combined with MeHg exposure could increase the risk of placental damage. 相似文献
999.
Alessandro Attanasi Andrea Cavagna Lorenzo Del Castello Irene Giardina Asja Jelic Stefania Melillo Leonardo Parisi Oliver Pohl Edward Shen Massimiliano Viale 《Journal of the Royal Society Interface》2015,12(108)
One of the most impressive features of moving animal groups is their ability to perform sudden coherent changes in travel direction. While this collective decision can be a response to an external alarm cue, directional switching can also emerge from the intrinsic fluctuations in individual behaviour. However, the cause and the mechanism by which such collective changes of direction occur are not fully understood yet. Here, we present an experimental study of spontaneous collective turns in natural flocks of starlings. We employ a recently developed tracking algorithm to reconstruct three-dimensional trajectories of each individual bird in the flock for the whole duration of a turning event. Our approach enables us to analyse changes in the individual behaviour of every group member and reveal the emergent dynamics of turning. We show that spontaneous turns start from individuals located at the elongated tips of the flocks, and then propagate through the group. We find that birds on the tips deviate from the mean direction of motion much more frequently than other individuals, indicating that persistent localized fluctuations are the crucial ingredient for triggering a collective directional change. Finally, we quantitatively verify that birds follow equal-radius paths during turning, the effects of which are a change of the flock''s orientation and a redistribution of individual locations in the group. 相似文献
1000.
Ellis N. ter Horst Nazanin Hakimzadeh Anja M. van der Laan Paul A. J. Krijnen Hans W. M. Niessen Jan J. Piek 《International journal of molecular sciences》2015,16(12):29583-29591
To diminish heart failure development after acute myocardial infarction (AMI), several preclinical studies have focused on influencing the inflammatory processes in the healing response post-AMI. The initial purpose of this healing response is to clear cell debris of the injured cardiac tissue and to eventually resolve inflammation and support scar tissue formation. This is a well-balanced reaction. However, excess inflammation can lead to infarct expansion, adverse ventricular remodeling and thereby propagate heart failure development. Different macrophage subtypes are centrally involved in both the promotion and resolution phase of inflammation. Modulation of macrophage subset polarization has been described to greatly affect the quality and outcome of healing after AMI. Therefore, it is of great interest to reveal the process of macrophage polarization to support the development of therapeutic targets. The current review summarizes (pre)clinical studies that demonstrate essential molecules involved in macrophage polarization that can be modulated and influence cardiac healing after AMI. 相似文献