全文获取类型
收费全文 | 667篇 |
免费 | 27篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 8篇 |
化学工业 | 253篇 |
金属工艺 | 26篇 |
机械仪表 | 18篇 |
建筑科学 | 37篇 |
矿业工程 | 5篇 |
能源动力 | 19篇 |
轻工业 | 51篇 |
水利工程 | 8篇 |
石油天然气 | 2篇 |
无线电 | 27篇 |
一般工业技术 | 114篇 |
冶金工业 | 30篇 |
原子能技术 | 7篇 |
自动化技术 | 90篇 |
出版年
2022年 | 24篇 |
2021年 | 32篇 |
2020年 | 9篇 |
2019年 | 5篇 |
2018年 | 19篇 |
2017年 | 23篇 |
2016年 | 24篇 |
2015年 | 13篇 |
2014年 | 29篇 |
2013年 | 57篇 |
2012年 | 24篇 |
2011年 | 43篇 |
2010年 | 19篇 |
2009年 | 46篇 |
2008年 | 26篇 |
2007年 | 27篇 |
2006年 | 19篇 |
2005年 | 20篇 |
2004年 | 16篇 |
2003年 | 20篇 |
2002年 | 12篇 |
2001年 | 15篇 |
2000年 | 10篇 |
1998年 | 2篇 |
1997年 | 4篇 |
1996年 | 7篇 |
1995年 | 5篇 |
1994年 | 7篇 |
1993年 | 4篇 |
1992年 | 7篇 |
1991年 | 2篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 6篇 |
1985年 | 9篇 |
1984年 | 11篇 |
1983年 | 11篇 |
1982年 | 9篇 |
1981年 | 9篇 |
1980年 | 9篇 |
1979年 | 6篇 |
1977年 | 3篇 |
1976年 | 6篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1970年 | 2篇 |
1956年 | 2篇 |
排序方式: 共有695条查询结果,搜索用时 21 毫秒
101.
We have evaluated the effects of selected minerals present in subsoil environment on the efficiency of lead removal from contaminated groundwaters using biofilms composed of sulfate-reducing microorganisms, and examined the stability of metal deposits after the biofilms had been temporarily exposed to the air. To quantify the studied effects, lead was immobilized in biofilms of Desulfovibrio desulfuricans grown anaerobically in two flat-plate flow reactors, one filled with hematite and the other with quartz. While the biofilms in both reactors were heterogeneous and consisted of voids and channels, the biofilms grown on hematite were denser, thicker, and more porous than those grown on quartz. The average H2S concentrations, measured using microelectrodes, were higher in the biofilms grown on quartz than those measured in the biofilms grown on hematite. During 18 weeks of operation, iron was continuously released from the hematite. Lead was immobilized more efficiently in the biofilms grown on quartz than it was in the biofilms grown on hematite. Lead deposits were partially reoxidized, especially in biofilms grown on hematite, and the biofilms in both reactors responded to the presence of oxygen by lowering their density and increasing the H2S production rate. 相似文献
102.
Zbigniew Lewandowski 《Water research》1985,19(5):589-596
The effect of chromium Cr6+ on bacterial denitrification was investigated. The long-term influence of chromium presence was observed in packed bed reactors using methanol, ethanol, n-propanol, n-butanol, sec-butanol, tert-butanol, iso-butanol and n-pentanol as the carbon and energy sources for denitrifiers. Short-term influence was investigated by the inhibition coefficient Ki determination within activated sludge under anoxic conditions. The measured inhibition constant Ki was equal to 84.2 mg l?1 Cr6+, independently of the kind of organic compound utilized as the electron donor for the bacterial system. The concepts of the reactor resistance to inhibition (RRI) and the resistance to inhibition (RI) have been evaluated. 相似文献
103.
Immobilization of heavy metals (Pb, Cu, Cr, Zn, Cd, Mn) in the mineral additions containing concrete composites 总被引:2,自引:0,他引:2
The presented work determines the level of heavy metals (Pb+2, Cu+2, Zn+2, Cr+6, Cd+2, Mn+2) immobilization in the composites produced using Ordinary Portland Cement (OPC) as well as of binders containing large amount of mineral additives in its composition-siliceous fly ash (FA), fluidized bed combustion ash (FFA) and ground granulated blast furnace slag (GGBFS). Heavy metals were introduced to cementitious materials in the form of soluble salts as well as components of hazardous wastes (medical ash, metallurgical dust). It has been stated, that the level of heavy metals immobilization is combined with composites composition. Majority of analyzed heavy metals, added to binders' composition in the form of heavy metal salts achieves high level of immobilization, in mortar based on binder with 85% GGBFS and 15% OPC. The lowest immobilization level was reached for chromium Cr+6 added to hardening mortars as Na2Cr2O72H2O. The level ranges from 85.97% in mortars made on blended binder (20% OPC, 30% FFA and 50% GGBFS) to 93.33% in mortar produced on OPC. The increase of the so-called immobilization degree with time of hardened material maturing was found. This should be attributed to the pozzolanic or pozzolanic/hydraulic properties of components used; their effect on microstructure of hardened material is also important. Mineral additions enter the hydration reactions in the mixtures and favor the formation of specific microstructure promoting the immobilization of hazardous elements. 相似文献
104.
Stephen P. Linder Zbigniew Korona Mieczyslaw M. Kokar 《Journal of Intelligent and Robotic Systems》1999,24(3):295-311
Symbolic reasoning about continuous dynamic systems requires consistent qualitative abstraction functions and a consistent symbolic model. Classically, symbolic reasoning systems have utilized a box partition of the system space to achieve qualitative abstraction, but boxes can not provide a consistent abstraction. Our Q2 methodology abstracts a provably consistent symbolic representation of noise-free general dynamic systems. However, the Q2 symbolic representation has not been previously evaluated for efficacy in the presence of noise. We evaluate the effects of noise on Q2 symbolic reasoning in the domain of maneuver detection. We demonstrate how the Q2 methodology derives a symbolic abstraction of a general dynamic system model used in evaluating maneuver detectors. Simulation results represented by ROC curves show that the Q2 based maneuver detector is superior to a box-based detector. While no method is consistent in the presence of noise, the Q2 methodology is superior to the classic box's approach for deriving qualitative decisions about noisy dynamic systems. 相似文献
105.
Tomasz Jan Kolanowski Weronika Wargocka-Matuszewska Agnieszka Zimna Lukasz Cheda Joanna Zyprych-Walczak Anna Rugowska Monika Drabik Micha Fiedorowicz Seweryn Krajewski ukasz Steczek Cezary Kozanecki Zbigniew Rogulski Natalia Rozwadowska Maciej Kurpisz 《International journal of molecular sciences》2021,22(22)
106.
Iaki Ucar Marco Gramaglia Marco Fiore Zbigniew Smoreda Esteban Moro 《Journal of the Royal Society Interface》2021,18(185)
Reliable and timely information on socio-economic status and divides is critical to social and economic research and policing. Novel data sources from mobile communication platforms have enabled new cost-effective approaches and models to investigate social disparity, but their lack of interpretability, accuracy or scale has limited their relevance to date. We investigate the divide in digital mobile service usage with a large dataset of 3.7 billion time-stamped and geo-referenced mobile traffic records in a major European country, and find profound geographical unevenness in mobile service usage—especially on news, e-mail, social media consumption and audio/video streaming. We relate such diversity with income, educational attainment and inequality, and reveal how low-income or low-education areas are more likely to engage in video streaming or social media and less in news consumption, information searching, e-mail or audio streaming. The digital usage gap is so large that we can accurately infer the socio-economic status of a small area or even its Gini coefficient only from aggregated data traffic. Our results make the case for an inexpensive, privacy-preserving, real-time and scalable way to understand the digital usage divide and, in turn, poverty, unemployment or economic growth in our societies through mobile phone data. 相似文献
107.
Agnieszka Siemieniuk Zbigniew Burdach Waldemar Karcz 《International journal of molecular sciences》2021,22(23)
Little is known about the effect of lead on the activity of the vacuolar K+ channels. Here, the patch-clamp technique was used to compare the impact of lead (PbCl2) on the slow-activating (SV) and fast-activating (FV) vacuolar channels. It was revealed that, under symmetrical 100-mM K+, the macroscopic currents of the SV channels exhibited a typical slow activation and a strong outward rectification of the steady-state currents, while the macroscopic currents of the FV channels displayed instantaneous currents, which, at the positive potentials, were about three-fold greater compared to the one at the negative potentials. When PbCl2 was added to the bath solution at a final concentration of 100 µM, it decreased the macroscopic outward currents of both channels but did not change the inward currents. The single-channel recordings demonstrated that cytosolic lead causes this macroscopic effect by a decrease of the single-channel conductance and decreases the channel open probability. We propose that cytosolic lead reduces the current flowing through the SV and FV channels, which causes a decrease of the K+ fluxes from the cytosol to the vacuole. This finding may, at least in part, explain the mechanism by which cytosolic Pb2+ reduces the growth of plant cells. 相似文献
108.
Artur Dybko Wojciech Wroblewski Janusz Maciejewski Zbigniew Brzozka Ryszard S. Romaniuk Jedrzej Kielkiewicz 《应用聚合物科学杂志》1996,59(4):719-723
The article presents a new idea of the application of polymer track membranes (PTM) for immobilization of a reagent in fiber optic chemical sensors. PTM was made of a poly(ethylene terephthalate) foil (10 μm in thickness, pores of 0.2 μm in diameter). The usefulness of membranes additionally covered by poly(vinyl chloride) was tested in a fiber optic redox titrator. The titrator utilized N,N′-diphenylbenzidine as a reagent which changes its absorbance in dependence on the redox potential. The measuring system is based on a lightemitting diode and a silicon photodiode connected to a bifurcated fiber optic bundle. The gain is in price and availability of the membrane. © 1996 John Wiley & Sons, Inc. 相似文献
109.
Hanna Lewandowska Andrzej Eljaszewicz Izabela Poplawska Marlena Tynecka Alicja Walewska Kamil Grubczak Jordan Holl Hady Razak Hady Slawomir Lech Czaban Joanna Reszec Grayna Przybytniak Wojciech Guszewski Jarosaw Sado Magorzata Dbrowska-Gralak Cezary Kowalewski Piotr Fiedor Tomasz Oldak Artur Kaminski Zbigniew Zimek Marcin Moniuszko 《International journal of molecular sciences》2021,22(16)
Gamma rays and electrons with kinetic energy up to 10 MeV are routinely used to sterilize biomaterials. To date, the effects of irradiation upon human acellular dermal matrices (hADMs) remain to be fully elucidated. The optimal irradiation dosage remains a critical parameter affecting the final product structure and, by extension, its therapeutic potential. ADM slides were prepared by various digestion methods. The influence of various doses of radiation sterilization using a high-energy electron beam on the structure of collagen, the formation of free radicals and immune responses to non-irradiated (native) and irradiated hADM was investigated. The study of the structure changes was carried out using the following methods: immunohistology, immunoblotting, and electron paramagnetic resonance (EPR) spectroscopy. It was shown that radiation sterilization did not change the architecture and three-dimensional structure of hADM; however, it significantly influenced the degradation of collagen fibers and induced the production of free radicals in a dose-dependent manner. More importantly, the observed effects did not disrupt the therapeutic potential of the new transplants. Therefore, radiation sterilization at a dose of 35kGy can ensure high sterility of the dressing while maintaining its therapeutic potential. 相似文献
110.
A series of nanostructured titanium oxide particles were synthesized by a simple wet chemical method and characterized by means of small-angle x-ray scattering (SAXS)/wide-angle x-ray scattering (WAXS), atomic force microscope (AFM), scanning electron microscope (SEM), transmission electron microscope (TEM), thermal analysis, and rheometry. Tetrabutyl titanate (TBT) and ethylene glycol (EG) can be combined to form either TiO(x) nanowires or smooth nanorods, and the molar ratio of TBT:EG determines which of these is obtained. Therefore, TiO(x) nanorods with a highly rough surface can be obtained by hydrolysis of TBT with the addition of cetyl-trimethyl-ammonium bromide (CTAB) as surfactant in an EG solution. Furthermore, TiO(x) nanorods with two sharp ends can be obtained by hydrolysis of TBT with the addition of salt (LiCl) in an EG solution. The AFM results show that the TiO(x) nanorods with rough surfaces are formed by the self-assembly of TiO(x) nanospheres. The electrorheological (ER) effect was investigated using a suspension of titanium oxide nanowires or nanorods dispersed in silicone oil. Oil suspensions of titanium oxide nanowires or nanorods exhibit a dramatic reorganization when submitted to a strong DC electric field and the particles aggregate to form chain-like structures along the direction of applied electric field. Two-dimensional SAXS images from chains of anisotropically shaped particles exhibit a marked asymmetry in the SAXS patterns, reflecting the preferential self-assembly of the particles in the field. The suspension of rough TiO(x) nanorods shows stronger ER properties than that of the other nanostructured TiO(x) particles. We find that the particle surface roughness plays an important role in modification of the dielectric properties and in the enhancement of the ER effect. 相似文献