全文获取类型
收费全文 | 1504篇 |
免费 | 100篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 18篇 |
综合类 | 1篇 |
化学工业 | 540篇 |
金属工艺 | 48篇 |
机械仪表 | 32篇 |
建筑科学 | 47篇 |
矿业工程 | 6篇 |
能源动力 | 42篇 |
轻工业 | 326篇 |
水利工程 | 2篇 |
石油天然气 | 4篇 |
武器工业 | 1篇 |
无线电 | 70篇 |
一般工业技术 | 262篇 |
冶金工业 | 22篇 |
原子能技术 | 10篇 |
自动化技术 | 179篇 |
出版年
2024年 | 3篇 |
2023年 | 11篇 |
2022年 | 69篇 |
2021年 | 95篇 |
2020年 | 40篇 |
2019年 | 50篇 |
2018年 | 73篇 |
2017年 | 79篇 |
2016年 | 79篇 |
2015年 | 66篇 |
2014年 | 80篇 |
2013年 | 129篇 |
2012年 | 101篇 |
2011年 | 98篇 |
2010年 | 73篇 |
2009年 | 72篇 |
2008年 | 60篇 |
2007年 | 57篇 |
2006年 | 39篇 |
2005年 | 34篇 |
2004年 | 26篇 |
2003年 | 22篇 |
2002年 | 28篇 |
2001年 | 13篇 |
2000年 | 10篇 |
1999年 | 14篇 |
1998年 | 11篇 |
1997年 | 14篇 |
1996年 | 19篇 |
1995年 | 8篇 |
1994年 | 8篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 12篇 |
1984年 | 12篇 |
1983年 | 9篇 |
1982年 | 11篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1979年 | 8篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1975年 | 2篇 |
排序方式: 共有1610条查询结果,搜索用时 9 毫秒
951.
Bartomiej Rogalewicz Magorzata Szczesio Ewa Poleszak Joanna Kowalczyk Bernadeta Szewczyk Bruno Cury Camargo Jacek Szczytko Marcin Witkowski Andrzej Fruziski Anita Raducka Robert Banasiak Agnieszka Czylkowska 《International journal of molecular sciences》2021,22(23)
Three new compounds, namely [HL]2+[CuCl4]2−, [HL]2+[ZnCl4]2−, and [HL]2+[CdCl4]2− (where L: imipramine) were synthesized and their physicochemical and biological properties were thoroughly investigated. All three compounds form isostructural, crystalline systems, which have been studied using Single-Crystal X-ray diffraction analysis (SC-XRD) and Fourier-transform infrared spectroscopy (FTIR). The thermal stability was investigated using thermogravimetric analysis (TGA) and melting points for all compounds have been determined. Magnetic measurements were performed in order to study the magnetic properties of the compounds. The above mentioned techniques allowed us to comprehensively examine the physicochemical properties of the newly obtained compounds. The biological activity was investigated using the number of Zebrafish tests, as it is one of the most common models for studying the impact of newly synthesized compounds on the central nervous system (CNS), since this model is very similar to the human CNS. 相似文献
952.
Jacek Ilow Dimitrios Hatzinakos 《International Journal of Adaptive Control and Signal Processing》1997,11(7):555-568
In this paper we consider detection of baseband signals in partial response signalling (PRS) systems in the presence of additive, coloured noise. The additive noise in the system is a mixture of Gaussian noise and impulsive noise modelled as an alpha-stable process. The dependence in observation samples results from the excess bandwidth in the matched filters of the receivers. The detectors proposed are based on a noise estimation–cancellation technique. In particular, by exploiting past decisions as well as past received samples, we estimate the noise and subsequently cancel it. We adopt two approaches for designing predictors: in the first we use a minimum mean square error (MMSE) criterion and we employ Volterra filters as predictors; in the second we use the minimum dispersion (MD) criterion and we limit our attention to linear predictors. The effects of the predictor order, the number of exploited samples and the filtering allocation on the system performance are examined through Monte Carlo simulations. It is demonstrated that the proposed detectors, while having simple structures, offer substantial performance improvements over conventional detectors. © 1997 John Wiley & Sons, Ltd. 相似文献
953.
The high rotational speeds and loads of gears operating in acceleration gearboxes causes problems related to the correct choice and design of journal or rolling bearings. In the case of journal bearings, these problems are connected with thermoelastohydrodynamic lubrication theory and the dynamics of the bearing system. However, of major importance is the problem of thermal effects in journal bearings. This has been considered for bearings used in a double‐helical gearbox with the pinion and output shaft operating in cylindrical journal bearings. The oil film pressure, temperature, viscosity distributions, and maximum and mean oil film temperatures have been determined. In calculations, laminar adiabatic and turbulent adiabatic models of oil films have been applied. The results of the calculations can be used in the design of cylindrical or other types of journal bearing in rotating machinery, including acceleration or reduction gearboxes. 相似文献
954.
Jacek Rysz Beata Franczyk Magdalena Rysz-Grzyska Anna Gluba-Brzzka 《International journal of molecular sciences》2022,23(13)
The modifications in genomic DNA methylation are involved in the regulation of normal and pathological cellular processes. The epigenetic regulation stimulates biological plasticity as an adaptive response to variations in environmental factors. The role of epigenetic changes is vital for the development of some diseases, including atherogenesis, cancers, and chronic kidney disease (CKD). The results of studies presented in this review have suggested that altered DNA methylation can modulate the expression of pro-inflammatory and pro-fibrotic genes, as well those essential for kidney development and function, thus stimulating renal disease progression. Abnormally increased homocysteine, hypoxia, and inflammation have been suggested to alter epigenetic regulation of gene expression in CKD. Studies of renal samples have demonstrated the relationship between variations in DNA methylation and fibrosis and variations in estimated glomerular filtration rate (eGFR) in human CKD. The unravelling of the genetic–epigenetic profile would enhance our understanding of processes underlying the development of CKD. The understanding of multifaceted relationship between DNA methylation, genes expression, and disease development and progression could improve the ability to identify individuals at risk of CKD and enable the choice of appropriate disease management. 相似文献
955.
Jacek Libicki 《Mine Water and the Environment》1982,1(1):25-30
Open-cast mining operations conducted below groundwater table often affect the drawdown of the water table over large areas which as a consequence changes the natural regional hydrological balance. Remedial measures may include construction of new water intakes, and changes in the land usage may be necessary. Tipping of wastes (most often coal wastes and ashes) affects ground water pollution. Instead of removal of effects, preventive methods are recommended. 相似文献
956.
A Zygler A Wasik A Kot-Wasik J Namieśnik 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2012,29(9):1391-1401
The objective of this study was to measure the concentrations of nine high-intensity sweeteners (acesulfame-K, aspartame, alitame, cyclamate, dulcin, neohesperidin DC, neotame, saccharin and sucralose) in different categories of food available on the Polish market. Over 170 samples of different brands of beverages, yoghurts, fruit preparations, vegetable preserves and fish products were analysed using an analytical procedure based on SPE and LC/MS. The results indicated that foodstuffs under the study generally comply with European Union legislation in terms of sweetener content. However, a few cases of food product mislabelling were detected, i.e. the use of cyclamate for non-approved applications. 相似文献
957.
T. Czyżewski 《Wear》1975,31(1):119-140
A theoretical analysis has been carried out of changes in the stress field in the elastohydrodynamic contact zone of cylindrical surfaces due to operating variables. Their possible role in rolling contact fatigue has been assessed by accelerated rolling contact fatigue tests. The results show that changes of the elastohydrodynamic pressure distribution in the contact zone associated with increase of the viscosity-velocity parameter induce considerable changes in the stress field in the contact zone. The poor correlation of rolling contact fatigue life with material effects according to elastohydrodynamic theory and the considerable changes in rolling contact fatigue life due to lubrication effects suggests that the explanation lies outside elastohydrodynamic theory and possibly in the theory of asperity lubrication. 相似文献
958.
Jacek Jagielski Lionel Thomé Sandra Moll 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(16):2698-2700
Meso (effect of grain size) and macroscopic (effect of sample dimension) considerations about damage accumulation processes are discussed. Although both factors may significantly influence damage accumulation kinetics, they are not taken into account in most of currently used models. The role of meso and macroscopic factors may be explained in the framework of a recently developed model of damage accumulation (Multi-Step Damage Accumulation - MSDA), which assumes that the damage build-up can be regarded as a sequence of structural transformations triggered by the destabilization of the current structure of a crystal induced by radiation damage. 相似文献
959.
Grzegorz Gawlik Jacek Jagielski Anna Stonert 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(16):2579-2582
Light emission from a silicon dioxide layer enriched with silicon has been studied. Samples used had structures made on thermally oxidized silicon substrate wafers. Excess silicon atoms were introduced into a 250-nm-thick silicon dioxide layer via implantation of 60 keV Si+ ions up to a fluence of 2 × 1017 cm−2. A 15-nm-thick Au layer was used as a top semitransparent electrode. Continuous blue light emission was observed under DC polarization of the structure at 8-12 MV/cm. The blue light emission from the structures was also observed in an ionoluminescence experiment, in which the light emission was caused by irradiation with a H2+ ion beam of energy between 22 and 100 keV. In the case of H2+, on entering the material the ions dissociated into two protons, each carrying on average half of the incident ion energy. The spectra of the emitted light and the dependence of ionoluminescence on proton energy were analyzed and the results were correlated with the concentration profile of implanted silicon atoms. 相似文献
960.