全文获取类型
收费全文 | 5288篇 |
免费 | 230篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 148篇 |
综合类 | 13篇 |
化学工业 | 1230篇 |
金属工艺 | 117篇 |
机械仪表 | 103篇 |
建筑科学 | 397篇 |
矿业工程 | 10篇 |
能源动力 | 121篇 |
轻工业 | 725篇 |
水利工程 | 35篇 |
石油天然气 | 13篇 |
无线电 | 296篇 |
一般工业技术 | 915篇 |
冶金工业 | 636篇 |
原子能技术 | 58篇 |
自动化技术 | 707篇 |
出版年
2021年 | 60篇 |
2020年 | 55篇 |
2019年 | 58篇 |
2018年 | 66篇 |
2017年 | 85篇 |
2016年 | 115篇 |
2015年 | 138篇 |
2014年 | 150篇 |
2013年 | 249篇 |
2012年 | 227篇 |
2011年 | 243篇 |
2010年 | 210篇 |
2009年 | 224篇 |
2008年 | 221篇 |
2007年 | 259篇 |
2006年 | 205篇 |
2005年 | 205篇 |
2004年 | 146篇 |
2003年 | 126篇 |
2002年 | 122篇 |
2001年 | 86篇 |
2000年 | 70篇 |
1999年 | 65篇 |
1998年 | 69篇 |
1997年 | 76篇 |
1996年 | 71篇 |
1995年 | 73篇 |
1994年 | 54篇 |
1993年 | 71篇 |
1992年 | 76篇 |
1991年 | 47篇 |
1990年 | 56篇 |
1989年 | 60篇 |
1988年 | 38篇 |
1987年 | 68篇 |
1986年 | 56篇 |
1985年 | 69篇 |
1984年 | 65篇 |
1983年 | 60篇 |
1982年 | 61篇 |
1981年 | 66篇 |
1980年 | 66篇 |
1979年 | 65篇 |
1978年 | 47篇 |
1977年 | 52篇 |
1976年 | 56篇 |
1975年 | 54篇 |
1974年 | 66篇 |
1973年 | 49篇 |
1970年 | 33篇 |
排序方式: 共有5524条查询结果,搜索用时 15 毫秒
1.
Kiran Kousar Thomas Ljungdahl Alexander Wetzel Michael Dowhyj Hans Oskarsson Alex S. Walton Monika S. Walczak Robert Lindsay 《Journal of surfactants and detergents》2020,23(1):225-234
An optimized one-pot recipe has been developed to synthesize a surfactant molecule, referred to as OMID, consisting of an imidazoline head group and aliphatic tail, which is an exemplar corrosion inhibitor for carbon steel in acidic solutions. As evidenced by gas chromatography, 1H and 13C nuclear magnetic resonance, and Fourier-transform infrared data, a high-purity product was achieved without the use of either a solvent or catalyst. Critical micelle concentration values and corrosion inhibition efficiencies ( η %) were determined in aqueous solutions of hydrochloric acid and sulfuric acid using surface tensiometry and linear polarization resistance measurements, respectively. Hydrolysis of the imidazoline head group as a function of pH (0–11) was explored with ultraviolet–visible absorption spectroscopy. In addition, N 1s and C 1s X-ray photoelectron spectroscopy data were acquired from both surface-adsorbed OMID and a multilayer of the imidazoline head group of OMID. These latter data are highly relevant to those attempting to understand OMID inhibition chemistry. 相似文献
2.
Theory of Computing Systems - In this article we undertake a study of extension complexity from the perspective of formal languages. We define a natural way to associate a family of polytopes with... 相似文献
3.
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
4.
5.
Jonas Ort Benedikt Kremer Linda Grüßer Romy Blaumeiser-Debarry Hans Clusmann Mark Coburn Anke Hllig Ute Lindauer 《International journal of molecular sciences》2020,21(23)
Effective pharmacological neuroprotection is one of the most desired aims in modern medicine. We postulated that a combination of two clinically used drugs—nimodipine (L-Type voltage-gated calcium channel blocker) and amiloride (acid-sensing ion channel inhibitor)—might act synergistically in an experimental model of ischaemia, targeting the intracellular rise in calcium as a pathway in neuronal cell death. We used organotypic hippocampal slices of mice pups and a well-established regimen of oxygen-glucose deprivation (OGD) to assess a possible neuroprotective effect. Neither nimodipine (at 10 or 20 µM) alone or in combination with amiloride (at 100 µM) showed any amelioration. Dissolved at 2.0 Vol.% dimethyl-sulfoxide (DMSO), the combination of both components even increased cell damage (p = 0.0001), an effect not observed with amiloride alone. We conclude that neither amiloride nor nimodipine do offer neuroprotection in an in vitro ischaemia model. On a technical note, the use of DMSO should be carefully evaluated in neuroprotective experiments, since it possibly alters cell damage. 相似文献
6.
AbstractAlthough fouling is a problem varying in space and time, sizing and assessment of a process apparatus is almost always based on one single integral fouling resistance value. Furthermore, the integral fluid dynamic behavior, e.g. the development of time-dependent pressure drop in a heat exchanger, can be influenced by local constrictions. While it is generally possible to determine the time dependency of the integral fouling behavior, local differences are not taken into consideration at present. Therefore, this paper introduces a metrological, an incremental and a segmental approach to study the local development of crystallization fouling by calcium sulfate in a countercurrent double-pipe heat exchanger. The consecutive approaches allow for thermal, volumetric, gravimetric, and optical fouling investigations, aiming to examine the axial distribution of deposit as well as local differences in the deposit morphology. All methods provided congruent results and local fouling could be described properly. An almost clean surface at the colder end of the heat exchanger and an exponential increase of deposit thickness were observed towards the hot end. Hence, the section near to the hot water inlet turned out to be a key area with regards to increasing fouling mass and structural changes of the layer. 相似文献
7.
Dr. Li Di Prof. Per Artursson Dr. Alex Avdeef Prof. Leslie Z. Benet Prof. J. Brian Houston Dr. Manfred Kansy Edward H. Kerns Prof. Hans Lennernäs Dr. Dennis A. Smith Prof. Kiyohiko Sugano 《ChemMedChem》2020,15(20):1862-1874
Passive permeability is a key property in drug disposition and delivery. It is critical for gastrointestinal absorption, brain penetration, renal reabsorption, defining clearance mechanisms and drug-drug interactions. Passive diffusion rate is translatable across tissues and animal species, while the extent of absorption is dependent on drug properties, as well as in vivo physiology/pathophysiology. Design principles have been developed to guide medicinal chemistry to enhance absorption, which combine the balance of aqueous solubility, permeability and the sometimes unfavorable compound characteristic demanded by the target. Permeability assays have been implemented that enable rapid development of structure-permeability relationships for absorption improvement. Future advances in assay development to reduce nonspecific binding and improve mass balance will enable more accurately measurement of passive permeability. Design principles that integrate potency, selectivity, passive permeability and other ADMET properties facilitate rapid advancement of successful drug candidates to patients. 相似文献
8.
9.
10.
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