全文获取类型
收费全文 | 5677篇 |
免费 | 476篇 |
国内免费 | 112篇 |
专业分类
电工技术 | 244篇 |
综合类 | 202篇 |
化学工业 | 983篇 |
金属工艺 | 196篇 |
机械仪表 | 191篇 |
建筑科学 | 350篇 |
矿业工程 | 53篇 |
能源动力 | 307篇 |
轻工业 | 463篇 |
水利工程 | 96篇 |
石油天然气 | 178篇 |
武器工业 | 5篇 |
无线电 | 649篇 |
一般工业技术 | 824篇 |
冶金工业 | 422篇 |
原子能技术 | 21篇 |
自动化技术 | 1081篇 |
出版年
2024年 | 17篇 |
2023年 | 93篇 |
2022年 | 168篇 |
2021年 | 220篇 |
2020年 | 172篇 |
2019年 | 173篇 |
2018年 | 216篇 |
2017年 | 201篇 |
2016年 | 239篇 |
2015年 | 214篇 |
2014年 | 232篇 |
2013年 | 434篇 |
2012年 | 332篇 |
2011年 | 422篇 |
2010年 | 343篇 |
2009年 | 340篇 |
2008年 | 283篇 |
2007年 | 242篇 |
2006年 | 237篇 |
2005年 | 192篇 |
2004年 | 133篇 |
2003年 | 147篇 |
2002年 | 195篇 |
2001年 | 146篇 |
2000年 | 105篇 |
1999年 | 63篇 |
1998年 | 111篇 |
1997年 | 78篇 |
1996年 | 62篇 |
1995年 | 62篇 |
1994年 | 53篇 |
1993年 | 44篇 |
1992年 | 25篇 |
1991年 | 8篇 |
1990年 | 19篇 |
1989年 | 10篇 |
1988年 | 15篇 |
1987年 | 15篇 |
1986年 | 13篇 |
1985年 | 11篇 |
1984年 | 25篇 |
1983年 | 14篇 |
1982年 | 18篇 |
1981年 | 15篇 |
1980年 | 10篇 |
1979年 | 13篇 |
1978年 | 14篇 |
1977年 | 12篇 |
1976年 | 20篇 |
1975年 | 9篇 |
排序方式: 共有6265条查询结果,搜索用时 15 毫秒
991.
阳离子淀粉对纤维黏附性能影响因素的分析 总被引:1,自引:1,他引:0
测试分析影响阳离子淀粉对纺织纤维黏附性的主要因素.通过测试阳离子淀粉的取代度以及粗纱浸浆时间和温度等因素对粗纱断裂强力等表征黏附性能指标的影响,得知:提高阳离子淀粉的含量和取代度,增加粗纱的浸浆时间和温度以及搅拌的时间和速度,有利于增强阳离子淀粉与纺织纤维之间的黏附力. 相似文献
992.
Fender A Rigg EJ Maier RR MacPherson WN Barton JS Moore AJ Jones JD Zhao D Zhang L Bennion I McCulloch S Jones BJ 《Applied optics》2006,45(36):9041-9048
We describe the use of arrayed waveguide gratings (AWGs) in the interrogation of fiber Bragg gratings (FBGs) for dynamic strain measurement. The ratiometric AWG output was calibrated in a static deflection experiment over a +/-200 microepsilon range. Dynamic strain measurement was demonstrated with a FBG in a conventional single-mode fiber mounted on the surface of a vibrating cantilever and on a piezoelectric actuator, giving a resolution of 0.5 microepsilon at 2.4 kHz. We present results of this technique extended to measure the dynamic differential strain between two FBG pairs within a multicore fiber. An arbitrary cantilever oscillation of the multicore fiber was determined from curvature measurements in two orthogonal axes at 1125 Hz with a resolution of 0.05 m(-1). 相似文献
993.
Glutamate microsensors form a promising analytical tool for monitoring neuronally derived glutamate directly in the brain. However, when a microsensor is implanted in brain tissue, many factors can diminish its performance. Consequently, a thorough characterization and evaluation of a microsensor is required concerning all factors that may possibly be encountered in vivo. The present report deals with the validation of a hydrogel-coated glutamate microsensor. This microsensor is constructed by coating a carbon fiber electrode (10-microm diameter; 300-500 microm long) with a five-component redox hydrogel, in which L-glutamate oxidase, horseradish peroxidase, and ascorbate oxidase are wired via poly(ethylene glycol) diglycidyl ether to an osmium-containing redox polymer. A thin Nafion coating completes the construction. Although this microsensor was previously used in vivo, information concerning its validation is limited. In the present study, attention was given to its selectivity, specificity, calibration, oxygen dependency, biofouling, operating potential dependency, and linear range. In addition, successful microsensor experiments in microdialysate, in vitro (in organotypic hippocampal slice cultures), and in vivo (in anesthesized rats) are shown. 相似文献
994.
Gerber BS Pagcatipunan M Smith EV Basu SS Lawless KA Smolin LI Berbaum ML Brodsky IG Eiser AR 《Journal of applied measurement》2006,7(1):55-73
The purpose of this research was to develop survey instruments to evaluate diabetes knowledge and self-efficacy in a diverse population, and investigate the psychometric properties of data obtained with these instruments using Rasch measurement. Two-hundred and fifty-five urban-dwelling participants with diabetes were recruited to complete surveys through independent interviews. To evaluate the association of health literacy on metabolic control, formal literacy and hemoglobin A1c fingerstick testing were performed. Rasch analysis of the data yielded item and person calibrations for self-efficacy and knowledge, with variable maps created to provide both norm and criterion-referenced interpretations. Knowledge scale person separation reliability was 0.50 and item separation reliability was 0.98; while self-efficacy scale person separation reliability was 0.72 with item separation reliability of 0.92. Statistically significant partial correlations were observed between knowledge and health literacy (r = 0.41, p<.001), and self-efficacy and hemoglobin A1c (r = -0.33, p<.001). However, there was no correlation between diabetes knowledge and hemoglobin A1c (r = 0.035, p = 0.29), or health literacy and A1c (r = 0.022, p = 0.36). Diabetes knowledge varied, with non-English speaking individuals having lower measures than English speakers (t(252) = -4.86, p<.001). Non-English speaking individuals also had lower self-efficacy measures than English speakers (t(251) = -2.68, p = .008). Current knowledge deficits and perceptions of self-management may be estimated visually through variable mapping, which may help in individualizing informational needs for people with diabetes. 相似文献
995.
Desigaux L Belkacem MB Richard P Cellier J Léone P Cario L Leroux F Taviot-Guého C Pitard B 《Nano letters》2006,6(2):199-204
The purpose of this study was to control the fabrication of new labile supramolecular assemblies by formulating associations of DNA molecules with inorganic layered double hydroxides (LDHs). The results show that LDH/DNA hybrids synthesized by a coprecipitation route involving the in situ formation of LDHs around DNA molecules acting as templates were characterized by a lamellar organization, with DNA molecules sandwiched between hydroxide layers, exhibiting a regular spacing of 1.96 nm. Our results indicate that labile complexes resulting from the association of nucleic acids and inorganic materials can be obtained not only by anion exchange but also by a direct self-assembly route. 相似文献
996.
Molina SI Ben T Sales DL Pizarro J Galindo PL Varela M Pennycook SJ Fuster D González Y González L 《Nanotechnology》2006,17(22):5652-5658
The compositional distribution in a self-assembled InAs(P) quantum wire grown by molecular beam epitaxy on an InP(001) substrate has been determined by electron energy loss spectrum imaging. We have determined the strain and stress fields generated in and around this wire capped with a 5?nm InP layer by finite element calculations using as input the compositional map experimentally obtained. Preferential sites for nucleation of wires grown on the surface of this InP capping layer are predicted, based on chemical potential minimization, from the determined strain and stress fields on this surface. The determined preferential sites for wire nucleation agree with their experimentally measured locations. The method used in this paper, which combines electron energy loss spectroscopy, high-resolution Z contrast imaging, and elastic theory finite element calculations, is believed to be a valuable technique of wide applicability for predicting the preferential nucleation sites of epitaxial self-assembled nano-objects. 相似文献
997.
998.
阴极开放式质子交换膜燃料电池实验性研究 总被引:1,自引:0,他引:1
文中围绕实验室自制的开放式阴极自增湿型质子交换膜燃料电池开展了大量相关实验,采用FLUKE Ti25红外温度成像仪测得了各种操作条件下电池表面温度分布图像。实验结果表明:在封闭式阳极(anode dead-end)操作条件下,液态水会在阳极逐渐积累而影响反应气的传质,造成电池输出性能的衰减。通过阳极排气可以使电池性能恢复。纵观电堆表面温度分布情况,总体呈现出沿氢气流道方向递增的趋势。且随着电流密度的增大,这种温度分布的不均匀性变得更加明显。在实验所测试的范围内,电堆的平均输出功率密度达到了583 mW/cm2。 相似文献
999.
A novel method using resistive pulse sensors for electrokinetic surface charge measurements of nanoparticles is presented. This method involves recording the particle blockade rate while the pressure applied across a pore sensor is varied. This applied pressure acts in a direction which opposes transport due to the combination of electro-osmosis, electrophoresis, and inherent pressure. The blockade rate reaches a minimum when the velocity of nanoparticles in the vicinity of the pore approaches zero, and the forces on typical nanoparticles are in equilibrium. The pressure applied at this minimum rate can be used to calculate the zeta potential of the nanoparticles. The efficacy of this variable pressure method was demonstrated for a range of carboxylated 200 nm polystyrene nanoparticles with different surface charge densities. Results were of the same order as phase analysis light scattering (PALS) measurements. Unlike PALS results, the sequence of increasing zeta potential for different particle types agreed with conductometric titration. 相似文献
1000.
T Zhang J Zhang D Hewitt B Tran X Gao ZJ Qiu M Tejada H Gazzano-Santoro YH Kao 《Analytical chemistry》2012,84(16):7112-7123
The heterogeneity in therapeutic antibodies arising from buried unpaired cysteines has not been well studied. This paper describes the characterization of two unpaired cysteines in a recombinant humanized IgG1 monoclonal antibody (referred to as mAb A). The reversed-phase high-performance liquid chromatography (RP-HPLC) analysis of mAb A samples showed three distinct peaks, indicating the presence of three species. The heterogeneities observed in the RP-HPLC have been determined to arise from unpaired cysteines (Cys-22 and Cys-96) that are buried in the V(H) domain. The Fab containing free thiols (referred to as "free-thiol Fab") and the Fab containing the disulfide (referred to as "intact Fab") of mAb A were generated through limited Lys-C digestion and purified with an ion exchange chromatography method. The binding of free-thiol Fab and intact Fab to its antigen was measured in a cell-based binding assay and an enzyme linked immunosorbent assay. The unpaired cysteines in the Fab of mAb A were found to have no significant impact on the binding to its target. Consistent with these Fab binding data, the enriched intact mAb A containing free thiols was determined to be fully active in a potency assay. The data reported here demonstrate that the redox status of cysteines is potentially a major source of heterogeneity for an antibody. 相似文献