全文获取类型
收费全文 | 556篇 |
免费 | 47篇 |
专业分类
电工技术 | 6篇 |
化学工业 | 171篇 |
金属工艺 | 14篇 |
机械仪表 | 13篇 |
建筑科学 | 22篇 |
能源动力 | 24篇 |
轻工业 | 61篇 |
水利工程 | 2篇 |
石油天然气 | 2篇 |
无线电 | 29篇 |
一般工业技术 | 114篇 |
冶金工业 | 14篇 |
原子能技术 | 9篇 |
自动化技术 | 122篇 |
出版年
2024年 | 1篇 |
2023年 | 10篇 |
2022年 | 32篇 |
2021年 | 36篇 |
2020年 | 19篇 |
2019年 | 12篇 |
2018年 | 18篇 |
2017年 | 20篇 |
2016年 | 32篇 |
2015年 | 22篇 |
2014年 | 33篇 |
2013年 | 40篇 |
2012年 | 34篇 |
2011年 | 38篇 |
2010年 | 39篇 |
2009年 | 53篇 |
2008年 | 30篇 |
2007年 | 35篇 |
2006年 | 13篇 |
2005年 | 24篇 |
2004年 | 22篇 |
2003年 | 11篇 |
2002年 | 10篇 |
2001年 | 3篇 |
2000年 | 8篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1993年 | 2篇 |
1989年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有603条查询结果,搜索用时 31 毫秒
31.
32.
Biagio Barone Luigi Napolitano Marco Abate Luigi Cirillo Pasquale Reccia Francesco Passaro Carmine Turco Simone Morra Francesco Mastrangelo Antonio Scarpato Ugo Amicuzi Vincenzo Morgera Lorenzo Romano Francesco Paolo Calace Savio Domenico Pandolfo Luigi De Luca Achille Aveta Enrico Sicignano Massimiliano Trivellato Gianluca Spena Carlo DAlterio Giovanni Maria Fusco Raffaele Vitale Davide Arcaniolo Felice Crocetto 《International journal of molecular sciences》2022,23(7)
Testosterone is the most important hormone in male health. Aging is characterized by testosterone deficiency due to decreasing testosterone levels associated with low testicular production, genetic factors, adiposity, and illness. Low testosterone levels in men are associated with sexual dysfunction (low sexual desire, erectile dysfunction), reduced skeletal muscle mass and strength, decreased bone mineral density, increased cardiovascular risk and alterations of the glycometabolic profile. Testosterone replacement therapy (TRT) shows several therapeutic effects while maintaining a good safety profile in hypogonadal men. TRT restores normal levels of serum testosterone in men, increasing libido and energy level and producing beneficial effects on bone density, strength and muscle as well as yielding cardioprotective effects. Nevertheless, TRT could be contraindicated in men with untreated prostate cancer, although poor findings are reported in the literature. In addition, different potential side effects, such as polycythemia, cardiac events and obstructive sleep apnea, should be monitored. The aim of our review is to provide an updated background regarding the pros and cons of TRT, evaluating its role and its clinical applicability in different domains. 相似文献
33.
34.
Influence of olive ripening degree and crusher typology on chemical and sensory characteristics of Correggiolo virgin olive oil 下载免费PDF全文
35.
Innocenzo Muzzalupo Massimiliano Pellegrino Enzo Perri 《European Food Research and Technology》2007,224(4):469-475
Characterization of genetic identity using DNA extracted from olive oil has the potential to facilitate assessment of origin
and varietal conformity. Such a prospect is particularly interesting in light of the increased regional spread of olive cultivars
and their various contributions to olive oil mixtures for certification of denomination of origin. Towards this goal, we have
devised a reliable method for extracting DNA from virgin olive oil that was utilized on monovariety oils from the single,
self-sterile cultivar ‘Ogliarola salentina’. We show that DNA purified from oil can be used for microsatellite analysis and
that the profile of DNA purified from a monovariety oil corresponds to the profile of DNA purified from the leaves of the
same cultivar. While DNA from the pollinators present in the genome of the seed embryo, could potentially contain alleles
not present in the genome fruit pulp, invalidating the molecular traceability of olive oil, we show for the first time that
there is no contamination of seed embryo DNA in a monovariety oil. Thus, this molecular assay is applicable for monovariety
olive oils. 相似文献
36.
Antonio Magrì Alessia Munzone Massimiliano Peana Serenella Medici Maria Antonietta Zoroddu Orjan Hansson Cristina Satriano Enrico Rizzarelli Diego La Mendola 《International journal of molecular sciences》2016,17(8)
Angiogenin (Ang) is a potent angiogenic factor, strongly overexpressed in patients affected by different types of cancers. The specific Ang cellular receptors have not been identified, but it is known that Ang–actin interaction induces changes both in the cell cytoskeleton and in the extracellular matrix. Most in vitro studies use the recombinant form (r-Ang) instead of the form that is normally present in vivo (“wild-type”, wt-Ang). The first residue of r-Ang is a methionine, with a free amino group, whereas wt-Ang has a glutamic acid, whose amino group spontaneously cyclizes in the pyro-glutamate form. The Ang biological activity is influenced by copper ions. To elucidate the role of such a free amino group on the protein–copper binding, we scrutinized the copper(II) complexes with the peptide fragments Ang(1–17) and AcAng(1–17), which encompass the sequence 1–17 of angiogenin (QDNSRYTHFLTQHYDAK-NH2), with free amino and acetylated N-terminus, respectively. Potentiometric, ultraviolet-visible (UV-vis), nuclear magnetic resonance (NMR) and circular dichroism (CD) studies demonstrate that the two peptides show a different metal coordination environment. Confocal microscopy imaging of neuroblastoma cells with the actin staining supports the spectroscopic results, with the finding of different responses in the cytoskeleton organization upon the interaction, in the presence or not of copper ions, with the free amino and the acetylated N-terminus peptides. 相似文献
37.
Some of the limits on fuel cell development include the issues of hydrogen availability and storage. Methanol has many advantages as an alternative fuel for fuel cells but depending on the anode composition, the formation of carbon may be a problem. In this paper, the direct utilization of methanol in solid oxide fuel cells with impregnated Ni/YSZ and Ni-Zr0.35Ce0.65O2−δ (ZDC)/YSZ anodes was investigated at 1073 K. Performance and stability of these anodes, as measured by steady-state polarization and electrochemical impedance spectroscopy, were improved by the presence of ZDC; although, the deposition of carbon, as detected by scanning electron microscopy and temperature-programmed oxidation analysis, was not entirely avoided. The impact of the carbon, however, was different depending on the anode. That is, carbon formation caused the delamination of impregnated Ni/YSZ anodes, while the structural integrity of Ni-ZDC/YSZ anodes was maintained and the cell performance was not negatively impacted. Increasing the fuel utilization decreased coking, as predicted by equilibrium calculations. 相似文献
38.
Massimiliano Ferronato Luca Bergamaschi Giuseppe Gambolati 《International journal for numerical methods in engineering》2010,81(3):381-402
Block constraint preconditioners are a most recent development for the iterative solution to large‐scale, often ill‐conditioned, coupled consolidation problems. A major limitation to their practical use, however, is the somewhat difficult selection of a number of user‐defined parameters (at least 4) in a more or less optimal way. The present paper investigates the robustness of three variants of the block constraint preconditioning in relation to the above parameters. A theoretical analysis of the eigenspectrum of the preconditioned matrix provides relatively simple bounds of the eigenvalues as a function of these parameters. A number of test problems used to validate the theoretical results show that both the mixed constraint preconditioner (MCP) combined with the symmetric quasi‐minimal residual (SQMR) solver and the MCP triangular variant (T‐MCP) combined with the bi‐conjugate gradient stabilized (Bi‐CGSTAB) are efficient and robust tools for the solution to difficult Finite Element‐discretized coupled consolidation problems. Moreover, the practical selection of the user‐defined parameters is relatively easy as a stable behavior is observed for a wide range of fill‐in degree values. The theoretical bounds on the eigenspectrum of the preconditioned matrix may help to suggest the most appropriate parameter combination. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
39.
Massimiliano Cimenti 《Journal of power sources》2010,195(13):3996-104
The direct utilization of methanol (MeOH) and ethanol (EtOH) was investigated on Cu-Co(Ru)/Zr0.35Ce0.65O2 anodes for solid oxide fuel cells (SOFC) prepared by impregnation. Cells had similar performance and stability in H2 and MeOH, while in EtOH the performance varied with time; that is, the power density initially increased, and then declined exponentially. This behavior was likely a consequence of carbon deposition that initially improved electronic conductivity to the anode functional layer, and subsequently blocked active sites. For all cells, the performance was recovered by re-exposing the anode to humidified hydrogen. In some cases, the cell performance exceeded the initial activity measured in hydrogen. Thus, the direct utilization of MeOH and EtOH did not irreversibly deactivate the Co(Ru)/Zr0.35Ce0.65O2 anodes. 相似文献
40.