全文获取类型
收费全文 | 4667篇 |
免费 | 200篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 64篇 |
综合类 | 2篇 |
化学工业 | 1275篇 |
金属工艺 | 164篇 |
机械仪表 | 89篇 |
建筑科学 | 115篇 |
矿业工程 | 12篇 |
能源动力 | 156篇 |
轻工业 | 580篇 |
水利工程 | 11篇 |
石油天然气 | 12篇 |
无线电 | 131篇 |
一般工业技术 | 725篇 |
冶金工业 | 1082篇 |
原子能技术 | 28篇 |
自动化技术 | 425篇 |
出版年
2023年 | 30篇 |
2022年 | 133篇 |
2021年 | 188篇 |
2020年 | 92篇 |
2019年 | 82篇 |
2018年 | 150篇 |
2017年 | 148篇 |
2016年 | 166篇 |
2015年 | 127篇 |
2014年 | 161篇 |
2013年 | 273篇 |
2012年 | 185篇 |
2011年 | 249篇 |
2010年 | 162篇 |
2009年 | 149篇 |
2008年 | 148篇 |
2007年 | 145篇 |
2006年 | 103篇 |
2005年 | 81篇 |
2004年 | 79篇 |
2003年 | 68篇 |
2002年 | 61篇 |
2001年 | 36篇 |
2000年 | 33篇 |
1999年 | 35篇 |
1998年 | 192篇 |
1997年 | 214篇 |
1996年 | 150篇 |
1995年 | 112篇 |
1994年 | 59篇 |
1993年 | 73篇 |
1992年 | 25篇 |
1991年 | 20篇 |
1990年 | 23篇 |
1989年 | 22篇 |
1988年 | 31篇 |
1987年 | 32篇 |
1986年 | 24篇 |
1985年 | 33篇 |
1984年 | 41篇 |
1983年 | 36篇 |
1982年 | 53篇 |
1981年 | 55篇 |
1980年 | 67篇 |
1979年 | 36篇 |
1978年 | 41篇 |
1977年 | 122篇 |
1976年 | 239篇 |
1975年 | 18篇 |
1973年 | 14篇 |
排序方式: 共有4871条查询结果,搜索用时 15 毫秒
121.
Mechanism of MxOy nanoparticles/CNTs for catalytic carbonization of polyethylene and application to flame retardancy 下载免费PDF全文
Karolina Wenelska Xuecheng Chen Beata Zielinska Ryszard J. Kaleńczuk Paul K. Chu Tao Tang Ewa Mijowska 《应用聚合物科学杂志》2017,134(34)
Three kinds of metal oxide nanoparticles (Fe3O4, Co3O4, and Ni2O3) are produced on carbon nanotubes (CNTs). The synergistic effects rendered by the CNTs and metal oxide nanoparticles on carbonization of polyethylene (PE) are studied and applications to flame retardancy of PE are investigated systematically. The CNT‐Ni2O3 delivers the best performance and the mechanism pertaining to the enhanced flame retardancy is proposed and discussed. It is found that under the same conditions, the carbonization rate can be a factor to influence the flame retardancy performance. Among Fe, Co, and Ni, Ni has the fastest carbonation rate, which leads to the best flame retardancy performance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45233. 相似文献
122.
Dorota Neugebauer Paulina Maksym‐Bębenek Anna Mielańczyk Tadeusz Biela 《Polymer Engineering and Science》2013,53(6):1146-1153
The reactive oxirane groups were incorporated into the macromolecule as substituents in the side chains of loosely‐grafted copolymer or in the arms of star‐shaped copolymer using glycidyl methacrylate (GMA) in the controlled atom transfer radical polymerization (ATRP). The branched GMA copolymers with various architectures were obtained by using hydrophobic copolymers containing six and seven units of caprolactone 2‐(methacryloyloxy)ethyl ester (CLMA) functionalized with bromoester groups, and trifunctional poly(ε‐caprolactone) (PCL), as well as hydrophilic tri‐, and six‐functional acetal derivatives of D ‐glucopyranosides as (macro)initiators with biodegradable and biocompatible properties. The well‐defined copolymers with core‐shell structures and polymerization degrees of GMA in the range of 20–100 per side chain/arm at 20–70% of monomer conversion within 1–6 h and narrow molecular weight distributions (Mw/Mn = 1.14–1.4) were obtained. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers 相似文献
123.
Synthesis of Novel Phosphonic‐Type Activity‐Based Probes for Neutrophil Serine Proteases and Their Application in Spleen Lysates of Different Organisms 下载免费PDF全文
Dr. Renata Grzywa Dr. Ewa Burchacka Maria Łęcka Dr. Łukasz Winiarski Maciej Walczak Agnieszka Łupicka‐Słowik Dr. Magdalena Wysocka Prof. Timo Burster Dr. Kamila Bobrek Dr. Keri Csencsits‐Smith Prof. Adam Lesner Dr. Marcin Sieńczyk 《Chembiochem : a European journal of chemical biology》2014,15(17):2605-2612
Neutrophils are a type of granulocyte important in the “first line of defense” of the innate immune system. Upon activation, they facilitate the destruction of invading microorganisms by the production of superoxide radicals, as well as the release of the enzymatic contents of their lysozymes. These enzymes include specific serine proteases: cathepsin G, neutrophil elastase, proteinase 3, as well as the recently discovered neutrophil serine protease 4 (NSP4). Under normal conditions, the proteolytic activity of neutrophil proteases is tightly regulated by endogenous serpins; however, this mechanism can be subverted during tissue stress, thereby resulting in the uncontrolled activity of serine proteases, which induce chronic inflammation and subsequent pathology. Herein, we describe the development of low‐molecular‐weight activity‐based probes that specifically target the active sites of neutrophil proteases. 相似文献
124.
This paper presents a fully automatic system intended to detect leaks of dielectric fluid in underground high-pressure, fluid-filled (HPFF) cables. The system combines a number of artificial intelligence (AI) and data processing techniques to achieve high detection capabilities for various rates of leaks, including leaks as small as 15 l per hour. The system achieves this level of precision mainly thanks to a novel auto-tuning procedure, enabling learning of the Bayesian network – the decision-making component of the system – using simulated leaks of various rates. Significant new developments extending the capabilities of the original leak detection system described in [1] and [2] form the basis of this paper. Tests conducted on the real-life HPFF cable system in New York City are also discussed. 相似文献
125.
M.E. Moneta R. Brzozowski P. Uznański 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(2):411-414
Thin films and foils of Fe73.5−xSi13.5B9Cu1Nb3Mnx, the FINEMET based amorphous and nanocrytalline alloys with high Mn doping (x = 9, 11, 13, 15 at%), were studied by means of transmission electron microscopy (TEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and with Mössbauer spectroscopy (MS), as-quenched (a-q) and after annealing (a). Mn, partially replacing Fe, causes common crystallisation temperature Tcr for the identified crystal structures, decrease of the lattice constants a0, c0, decrease of hyperfine parameters: magnetic field Hhf and isomer shift IS for amorphous phases and in consequence the Curie temperature TCu. 相似文献
126.
Karolina Ossowska Agata Motyka-Pomagruk Natalia Kaczyska Agnieszka Kowalczyk Wojciech Sledz Ewa Lojkowska Zbigniew Kaczyski 《International journal of molecular sciences》2022,23(4)
Pectobacterium parmentieri is a pectinolytic plant pathogenic bacterium causing high economic losses of cultivated plants. The highly devastating potential of this phytopathogen results from the efficient production of plant cell wall-degrading enzymes, i.e., pectinases, cellulases and proteases, in addition to the impact of accessory virulence factors such as motility, siderophores, biofilm and lipopolysaccharide (LPS). LPS belongs to pathogen-associated molecular patterns (PAMPs) and plays an important role in plant colonization and interaction with the defense systems of the host. Therefore, we decided to investigate the heterogeneity of O-polysaccharides (OPS) of LPS of different strains of P. parmentieri, in search of an association between the selected genomic and phenotypic features of the strains that share an identical structure of the OPS molecule. In the current study, OPS were isolated from the LPS of two P. parmentieri strains obtained either in Finland in the 1980s (SCC3193) or in Poland in 2013 (IFB5432). The purified polysaccharides were analyzed by utilizing 1D and 2D NMR spectroscopy (1H, DQF-COSY, TOCSY, ROESY, HSQC, HSQC-TOCSY and HMBC) in addition to chemical methods. Sugar and methylation analyses of native polysaccharides, absolute configuration assignment of constituent monosaccharides and NMR spectroscopy data revealed that these two P. parmentieri strains isolated in different countries possess the same structure of OPS with a very rare residue of 5,7-diamino-3,5,7,9-tetradeoxy-l-glycero-l-manno-non-2-ulosonic acid (pseudaminic acid) substituted in the position C-8: →3)-β-d-Galf-(1→3)-α-d-Galp-(1→8)-β-Pse4Ac5Ac7Ac-(2→6)-α-d-Glcp-(1→6)-β-d-Glcp-(1→. The previous study indicated that three other P. parmentieri strains, namely IFB5427, IFB5408 and IFB5443, exhibit a different OPS molecule than SCC3193 and IFB5432. The conducted biodiversity-oriented assays revealed that the P. parmentieri IFB5427 and IFB5408 strains possessing the same OPS structure yielded the highest genome-wide similarity, according to average nucleotide identity analyses, in addition to the greatest ability to macerate chicory tissue among the studied P. parmentieri strains. The current research demonstrated a novel OPS structure, characteristic of at least two P. parmentieri strains (SCC3193 and IFB5432), and discussed the observed heterogenicity in the OPS of P. parmentieri in a broad genomic and phenotype-related context. 相似文献
127.
One of the strategies in the search for safe and effective analgesic drugs is the design of multitarget analgesics. Such compounds are intended to have high affinity and activity at more than one molecular target involved in pain modulation. In the present contribution we summarize the attempts in which fentanyl or its substructures were used as a μ-opioid receptor pharmacophoric fragment and a scaffold to which fragments related to non-opioid receptors were attached. The non-opioid ‘second’ targets included proteins as diverse as imidazoline I2 binding sites, CB1 cannabinoid receptor, NK1 tachykinin receptor, D2 dopamine receptor, cyclooxygenases, fatty acid amide hydrolase and monoacylglycerol lipase and σ1 receptor. Reviewing the individual attempts, we outline the chemistry, the obtained pharmacological properties and structure-activity relationships. Finally, we discuss the possible directions for future work. 相似文献
128.
Comparative results of explosive decomposition equation and explosion parameter calculations of several high explosives are described. Calculations were carried out by two different algorithms. Results of calculations are compared with literature data. Some corrections of simple Kamlet's formulae for detonation parameter calculations are proposed adjusting the formulae to calculated explosion parameters. 相似文献
129.
Marek Kułażyński Sławomir Jabłoński Jan Kaczmarczyk Łukasz Świątek Katarzyna Pstrowska Marcin Łukaszewicz 《能源学会志》2018,91(5):668-675
The technological problems occurring in the co-firing of biomass and brown coal (lignite) prompted this research project. During the fuel preparation, accidental self-ignition and explosions were several times reported by power plants operators. The aim of this study was to evaluate brown coal, sunflower husks and sunflower husk pellets as fuels for co-firing in energetic boilers. Sunflower husk had a lower ash content and calorific value than the pellets. The range of the combustion temperatures of the biomass (200–300 °C) was narrower than that of brown coal (200–800 °C). The formation of highly alkaline ash from the biomass resulted in the formation in boiler of agglomerates of ash. The elemental composition, thermogravimetric and biological analyses suggested that the pellets contained synthetic additives difficult to identify. The biological method was proposed for evaluating biomass additives. The use of additional agents in the pelletizing process may influence on the combustion parameters. Mixing biomass with brown coal may occasionally result in self-ignition in the logistic chain. Plastic additives and biological activity may contribute to self-ignition. 相似文献
130.
Presented paper deals with the catalytic decomposition of hydrocarbons (methane and toluene) in the aspect of H2 production and types of obtained carbon deposits. The catalyst used in our studies was nickel supported on ceria–zirconia (Ni/CeZrO2). The aim of this work was to investigate the reactivity of obtained carbon deposits with H2O. Both issues are of great importance for determining the mechanisms of carbon deposits formation and their suppression during steam reforming reaction. 相似文献