全文获取类型
收费全文 | 4006篇 |
免费 | 192篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 65篇 |
综合类 | 3篇 |
化学工业 | 1029篇 |
金属工艺 | 113篇 |
机械仪表 | 75篇 |
建筑科学 | 134篇 |
矿业工程 | 13篇 |
能源动力 | 99篇 |
轻工业 | 326篇 |
水利工程 | 32篇 |
石油天然气 | 23篇 |
无线电 | 405篇 |
一般工业技术 | 697篇 |
冶金工业 | 656篇 |
原子能技术 | 31篇 |
自动化技术 | 503篇 |
出版年
2024年 | 10篇 |
2023年 | 33篇 |
2022年 | 122篇 |
2021年 | 124篇 |
2020年 | 81篇 |
2019年 | 85篇 |
2018年 | 84篇 |
2017年 | 122篇 |
2016年 | 142篇 |
2015年 | 105篇 |
2014年 | 149篇 |
2013年 | 211篇 |
2012年 | 180篇 |
2011年 | 215篇 |
2010年 | 189篇 |
2009年 | 165篇 |
2008年 | 180篇 |
2007年 | 178篇 |
2006年 | 139篇 |
2005年 | 122篇 |
2004年 | 103篇 |
2003年 | 91篇 |
2002年 | 110篇 |
2001年 | 67篇 |
2000年 | 68篇 |
1999年 | 52篇 |
1998年 | 196篇 |
1997年 | 102篇 |
1996年 | 101篇 |
1995年 | 87篇 |
1994年 | 59篇 |
1993年 | 60篇 |
1992年 | 32篇 |
1991年 | 28篇 |
1990年 | 31篇 |
1989年 | 30篇 |
1988年 | 25篇 |
1987年 | 31篇 |
1986年 | 33篇 |
1985年 | 26篇 |
1984年 | 27篇 |
1983年 | 24篇 |
1982年 | 13篇 |
1981年 | 22篇 |
1980年 | 21篇 |
1979年 | 13篇 |
1977年 | 14篇 |
1976年 | 25篇 |
1975年 | 11篇 |
1974年 | 10篇 |
排序方式: 共有4204条查询结果,搜索用时 15 毫秒
101.
M. Guadalupe Rodríguez‐Delgado Isaura G. Yáñez‐Flores Saul Sánchez‐Valdes Oliverio S. Rodriguez‐Fernandez Rebecca Betancourt‐Galindo Tomas Lozano‐Ramirez Eduardo Ramirez‐Vargas Hortencia Ortega‐Ortiz 《应用聚合物科学杂志》2013,130(4):2713-2721
Hydrogel silver nanocomposites have been used in applications with excellent antibacterial performance. Acrylic acid (AA)/itaconic acid (IA) hydrogels silver nanocomposites were prepared and applied as a coating on a textile substrate. Hydrogel matrices were synthesized first by the polymerization of an AA/IA aqueous (80/20 v/v) solution and mixed with 2‐2‐azobis(2‐methylpropionamide) diclorohydrate and N,N′‐methylene bisacrylamide until the hydrogel was formed. Silver nanoparticles were generated throughout the hydrogel networks with an in situ method via the incorporation of the silver ions and subsequent reduction with sodium borohydride. Cotton (C) and cotton/polyester (CP) textile fibers were then coated with these hydrogel silver nanocomposites. The influence of these nanocomposite hydrogels on the properties of the textile fiber were investigated by infrared spectroscopy (attenuated total reflectance), scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, and antibacterial tests against Pseudomona aeruginosa and Staphylococcus aureus. The better conditions, in which no serious aggregation of the silver nanoparticles occurred, were determined. It was proven that the textiles coated with hydrogels containing nanosilver had an excellent antibacterial abilities. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2713–2721, 2013 相似文献
102.
103.
Dr. Roman J. Lichtenecker Dr. Bernhard Ellinger Dr. Hong‐Mei Han Kirtikumar B. Jadhav Dr. Sascha Baumann Dr. Oliwia Makarewicz Dr. Markus Grabenbauer Prof. Dr. Hans‐Dieter Arndt 《Chembiochem : a European journal of chemical biology》2013,14(18):2492-2499
Growing resistance to antibiotics, as well as newly emerging pathogens, stimulate the investigation of antimicrobial peptides (AMPs) as therapeutic agents. Here, we report a new library design concept based on a stochastic distribution of natural AMP amino acid sequences onto half‐length synthetic peptides. For these compounds, a non‐natural motif of alternating D ‐ and L ‐backbone stereochemistry of the peptide chain predisposed for β‐helix formation was explored. Synthetic D ‐/L ‐peptides with permuted half‐length sequences were delineated from a full‐length starter sequence and covalently recombined to create two‐dimensional compound arrays for antibacterial screening. Using the natural AMP magainin as a seed sequence, we identified and iteratively optimized hit compounds showing high antimicrobial activity against Gram‐positive and Gram‐negative bacteria with low hemolytic activity. Cryo‐electron microscopy characterized the membrane‐associated mechanism of action of the new D ‐/L ‐peptide antibiotics. 相似文献
104.
Mark A. Rodriguez Terry J. Garino David X. Rademacher Xiaoyi Zhang Tina M. Nenoff 《Journal of the American Ceramic Society》2013,96(9):2966-2972
Barium‐substituted CsAlSi2O6 pollucites, CsxBa(1?x)/2AlSi2O6, and barium‐ and iron‐substituted pollucites, CsxBa(1?x)/2AlxFe1?xSi2O6 and CsxBa1?xAlxFe1?xSi2O6 were synthesized with 1 ≥ x≥ 0.7 using a hydrothermal synthesis procedure. Rietveld analysis of X‐ray diffraction data confirmed the substitution of Ba for Cs and Fe for Al, respectively. The crystallographic analysis also describes the effects of three different types of pollucite substitutions on the pollucite unit cell: Ba2+ for Cs1+ cation results in little effect on cell dimensions, intermediate concentrations of Ba2+ and Fe3+ substitution result in net minor expansion due to Fe3+ addition, and large Ba and Fe substitutions result in overall framework contraction. Elemental analysis combined with microscopy further supports the phase purity of these new phases. These materials can be used to study the stability of CsAlSi2O6 as a durable ceramic waste form, which could accommodate with time Cs and its decay product, Ba. Furthermore, success in iron substitution for aluminum into the pollucite lattice predicts that redox charge compensation for Cs cation decay is possible. 相似文献
105.
Maria M Velencoso Agustin SB Gonzalez Joaquin C García‐Martínez Maria J Ramos Antonio De Lucas Juan F Rodriguez 《Polymer International》2013,62(5):783-790
A simple strategy for the synthesis and functionalization of polyurethanes is described. Anionic ring‐opening polymerization was combined with ‘click’ chemistry to synthesize polyols with fluorescent properties. This route allows the incorporation of a wide range of functionalities in the polyols with an easy, clean and highly selective process compatible with several types of functional groups. The proposed strategy opens the way to the production, in a cost‐effective way, of ‘smart’ polyurethanes with non‐conventional properties like fire retardancy, antimite properties, antibacterial properties, etc. Alkynyl groups were introduced into the polyol chains by the controlled addition of glycidyl propargyl ether as co‐monomer during a conventional anionic ring‐opening copolymerization with propylene oxide. Subsequently 4‐azidomethyl‐7‐methoxycoumarin molecules were introduced onto the alkynyl‐polyether polyols by copper‐catalysed cycloaddition reactions to produce end‐functionalized polyols. The chemical structure of the novel polyols was characterized using infrared spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography with triple detection and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectroscopy. These characterization techniques confirmed the presence of a considerable amount of functional groups in the structure of the polyols. Finally, various fluorescent rigid foams, based on the functionalized polyols, were synthesized. Copyright © 2012 Society of Chemical Industry 相似文献
106.
Santhosh Kumar Vankayala Ramaiah Roman Günthner Maciej Lech Hans-Joachim Anders 《International journal of molecular sciences》2013,14(7):13213-13230
The cell type-, organ-, and species-specific expression of the Toll-like receptors (TLRs) are well described, but little is known about the respective expression profiles of their accessory molecules. We therefore determined the mRNA expression levels of LBP, MD2, CD36, CD14, granulin, HMGB1, LL37, GRP94, UNC93b1, TRIL, PRAT4A, AP3B1, AEP and the respective TLRs in human and mouse solid organs. Humans and mice displayed significant differences between their respective mRNA expression patterns of these factors. In addition, the expression profiles in transient tissue inflammation upon renal ischemia-reperfusion injury, in spleens and kidneys from mice with lupus-like systemic autoimmunity, and in progressive tissue fibrosis upon unilateral ureteral obstruction were studied. Several TLR co-factors were specifically regulated during the different phases of these disease entities, suggesting a functional involvement in the disease process. Thus, the organ- and species-specific expression patterns need to be considered in the design and interpretation of studies related to TLR-mediated innate immunity, which seems to be involved in the tissue injury phase, in the phase of tissue regeneration, and in progressive tissue remodelling. 相似文献
107.
Lucjan Chmielarz Piotr Kutrowski Alicja Rafalska-asocha Roman Dziembaj 《Applied catalysis. B, Environmental》2005,58(3-4):235-244
The selective catalytic oxidation of ammonia to nitrogen (NH3-SCO) has been studied over hydrotalcite derived mixed metal oxides containing Cu, Co, Fe or Ni. XRD, BET, NH3-TPD and TPR techniques were used for catalysts characterization. Results of NH3-SCO were compared with those of selective catalytic reduction of NO with NH3 (NO-SCR). Reaction mechanism was studied by temperature-programmed surface reaction (TPSR) and activity tests with a various contact time. Catalytic performance of the studied samples depends on both kind and loading of transition metals in the mixed metal oxide system. The Cu-containing samples have been found to be the most active catalysts of the NH3-SCO process. Transition metal loading strongly influences distribution of ammonia oxidation products. The highest selectivity to N2 was measured for the catalysts with the lowest transition metal content. 相似文献
108.
Summary By reacting esterification of phenolphtalein with methacrylate chloride, phenolphtalein dimethacrylate was obtained. Based on the results of elemental analysis, FTIR, 1H-NMR and 13C-NMR spectra, the structure of the product was proposed. The dimethacrylate was used as new crosslinker to crosslink poly(methyl methacrylate) (PMMA). The influence of the amount dimethacrylate on the crosslink density and some properties of the crosslinked polymers networks such as swelling, mechanical properties (tensile strength and elongation at break) and thermal stability were examined. 相似文献
109.
Elena V. Mitroshina Maria M. Loginova Roman S. Yarkov Mark D. Urazov Maria O. Novozhilova Mikhail I. Krivonosov Mikhail V. Ivanchenko Maria V. Vedunova 《International journal of molecular sciences》2022,23(2)
Ischemic brain injury is a widespread pathological condition, the main components of which are a deficiency of oxygen and energy substrates. In recent years, a number of new forms of cell death, including necroptosis, have been described. In necroptosis, a cascade of interactions between the kinases RIPK1 and RIPK3 and the MLKL protein leads to the formation of a specialized death complex called the necrosome, which triggers MLKL-mediated destruction of the cell membrane and necroptotic cell death. Necroptosis probably plays an important role in the development of ischemia/reperfusion injury and can be considered as a potential target for finding methods to correct the disruption of neural networks in ischemic damage. In the present study, we demonstrated that blockade of RIPK1 kinase by Necrostatin-1 preserved the viability of cells in primary hippocampal cultures in an in vitro model of glucose deprivation. The effect of RIPK1 blockade on the bioelectrical and metabolic calcium activity of neuron-glial networks in vitro using calcium imaging and multi-electrode arrays was assessed for the first time. RIPK1 blockade was shown to partially preserve both calcium and bioelectric activity of neuron-glial networks under ischemic factors. However, it should be noted that RIPK1 blockade does not preserve the network parameters of the collective calcium dynamics of neuron-glial networks, despite the maintenance of network bioelectrical activity (the number of bursts and the number of spikes in the bursts). To confirm the data obtained in vitro, we studied the effect of RIPK1 blockade on the resistance of small laboratory animals to in vivo modeling of hypoxia and cerebral ischemia. The use of Necrostatin-1 increases the survival rate of C57BL mice in modeling both acute hypobaric hypoxia and ischemic brain damage. 相似文献
110.
Shi‐Shen Liaw Oselys Rodriguez Justo Victor Haber Perez Shuai Zhou Manuel Garcia‐Perez 《化学工程与技术》2016,39(10):1828-1834
Ozonation on the phenols present in pyrolytic aqueous phases attained from biomass thermochemical conversion was evaluated. During ozonation, the dark color of original samples was found to decrease as a function of ozonation time. The oxidation kinetics of phenols was quantified by a method based on the color changes of samples. The oxidation profiles showed different behaviors and in some cases the phenols presented a positive correlation with the relative R color parameter, except eugenol, syringol, and vanillin which were markedly different. Finally, the color changes observed seem to be associated with the changes in the overall content of phenols and with the change in the molecular weight of the heavy fractions that include lignin oligomers. 相似文献