全文获取类型
收费全文 | 515篇 |
免费 | 31篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 3篇 |
综合类 | 1篇 |
化学工业 | 161篇 |
金属工艺 | 6篇 |
机械仪表 | 17篇 |
建筑科学 | 6篇 |
能源动力 | 12篇 |
轻工业 | 10篇 |
水利工程 | 2篇 |
石油天然气 | 15篇 |
武器工业 | 1篇 |
无线电 | 45篇 |
一般工业技术 | 174篇 |
冶金工业 | 43篇 |
原子能技术 | 7篇 |
自动化技术 | 46篇 |
出版年
2023年 | 5篇 |
2022年 | 20篇 |
2021年 | 18篇 |
2020年 | 19篇 |
2019年 | 20篇 |
2018年 | 26篇 |
2017年 | 26篇 |
2016年 | 19篇 |
2015年 | 8篇 |
2014年 | 21篇 |
2013年 | 20篇 |
2012年 | 41篇 |
2011年 | 39篇 |
2010年 | 22篇 |
2009年 | 22篇 |
2008年 | 33篇 |
2007年 | 24篇 |
2006年 | 14篇 |
2005年 | 10篇 |
2004年 | 11篇 |
2003年 | 15篇 |
2002年 | 11篇 |
2001年 | 4篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 10篇 |
1997年 | 5篇 |
1996年 | 8篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 7篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1986年 | 1篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 3篇 |
1969年 | 1篇 |
1956年 | 2篇 |
排序方式: 共有549条查询结果,搜索用时 15 毫秒
101.
Singhal R Orynbayeva Z Kalyana Sundaram RV Niu JJ Bhattacharyya S Vitol EA Schrlau MG Papazoglou ES Friedman G Gogotsi Y 《Nature nanotechnology》2011,6(1):57-64
Glass micropipettes, atomic force microscope tips and nanoneedles can be used to interrogate cells, but these devices either have conical geometries that can damage cells during penetration or are incapable of continuous fluid handling. Here, we report a carbon-nanotube-based endoscope for interrogating cells, transporting fluids and performing optical and electrochemical diagnostics at the single organelle level. The endoscope, which is made by placing a multiwalled carbon nanotube (length, 50-60?μm) at the tip of a glass pipette, can probe the intracellular environment with a spatial resolution of ~100?nm and can also access organelles without disrupting the cell. When the nanotube is filled with magnetic nanoparticles, the endoscope can be remotely manoeuvered to transport nanoparticles and attolitre volumes of fluids to and from precise locations. Because they are mounted on conventional glass micropipettes, the endoscopes readily fit standard instruments, creating a broad range of opportunities for minimally invasive intracellular probing, drug delivery and single-cell surgery. 相似文献
102.
Niu JJ Schrlau MG Friedman G Gogotsi Y 《Small (Weinheim an der Bergstrasse, Germany)》2011,7(4):540-545
Gold nanoparticle-decorated carbon nanotubes (CNTs) are used to study intracellular environments in situ using surface-enhanced Raman spectroscopy (SERS). CNTs are decorated with gold nanoparticles and assembled onto the tips of pulled glass capillaries to form a SERS-enabled endoscope. The sub-micrometer size and high mechanical strength of the endoscope make it possible to penetrate the cell membrane for intracellular probing and remain positioned inside during lengthy SERS measurements without causing damage to the cell. Using the SERS-enabled endoscope, DNA and other biomolecules are detected in situ within the nucleus of a single human cervical carcinoma cell in a minimally invasive manner. The SERS-enabled endoscopes exhibit high selectivity and sensitivity for detecting trace amounts of analytes (≈1 pM) in biofluid environments, highlighting their capabilities as label-free, biological sensors for real-time in situ cellular diagnostics, biological detection, and pharmaceutical research. 相似文献
103.
Abstract
Solid catalyst systems comprised of ruthenium hydroxide supported on magnesium-based carrier materials (spinel, magnesium oxide and hydrotalcite) were investigated for the selective, aqueous aerobic oxidation of the biomass-derived chemical 5-hydroxymethylfurfural into 2,5-furandicarboxylic acid (FDA), a possible plastics precursor. The novel catalyst systems were characterized by nitrogen physisorption, XRPD, TEM and EDS analysis, and applied for the oxidation with no added base at moderate to high pressures of dioxygen and elevated temperatures. The effects of support, temperature and oxidant pressure were studied and optimized to allow a quantitative yield of FDA to be obtained. 相似文献104.
Mass spectrometry-based qualitative and quantitative (bio)molecular analysis is a corner stone in the state-of-the-art pipelines in systems biology and environmental sciences. High-resolution and efficient tandem mass spectrometry methods and techniques are the essential analytical capabilities for the in-depth analysis of extremely complex mixtures of (bio)molecules of a very broad dynamic range of concentrations. Here, we briefly review the advantages and limitations of the current mass spectrometry with a focus on resolution, or resolving power, and methods of (bio)molecular fragmentation in the gas phase. We conclude with an outlook that considers possible avenues for further mass spectrometry-based method and technique development, indispensable for advancing the challenging real-life mass spectrometry applications in the XXI century. 相似文献
105.
Samantilleke AP Rebouta LM Garim V Rubio-Peña L Lanceros-Mendez S Alpuim P Carvalho S Kudrin AV Danilov YA 《Nanoscale research letters》2011,6(1):309
In this study, transparent conducting nanocrystalline ZnO:Ga (GZO) films were deposited by dc magnetron sputtering at room temperature on polymers (and glass for comparison). Electrical resistivities of 8.8 × 10-4 and 2.2 × 10-3 Ω cm were obtained for films deposited on glass and polymers, respectively. The crack onset strain (COS) and the cohesive strength of the coatings were investigated by means of tensile testing. The COS is similar for different GZO coatings and occurs for nominal strains approx. 1%. The cohesive strength of coatings, which was evaluated from the initial part of the crack density evolution, was found to be between 1.3 and 1.4 GPa. For these calculations, a Young's modulus of 112 GPa was used, evaluated by nanoindentation. 相似文献
106.
Yury Yuryev 《Polymer》2011,52(3):708-3487
Surface nucleation of poly(l/d-lactide) at the interface with aluminum was studied by performing isothermal DSC analysis of amorphous samples of varying thickness between 100 °C and 130 °C. To ensure complete wetting of the aluminum surface, a hot melt laminating process was used to prepare the samples. Theoretical aspects of surface crystallization kinetics were explored and the resulting model was compared with the results of Monte-Carlo simulations. Three stages of surface crystallization were identified depending on the growth geometry: (1) impingement-free growth, (2) increasingly laterally-constrained transverse growth, and (3) interstitial growth. By fitting the Monte-Carlo simulation to the experimental half-times of crystallization the surface nucleation concentration and the bulk nucleation rate was estimated at 4 different temperatures. It was found that both surface nucleation concentration and the bulk nucleation concentration decrease with increasing crystallization temperature. 相似文献
107.
V. P. Lyalyuk I. G. Tovarovskii A. K. Tarakanov V. N. Zakharchenko D. A. Kassim 《Steel in Translation》2014,44(1):34-37
The use of pulverized coal in steel plants depends on the supply of high-quality coke and iron ore to the blast furnace. In current conditions, it is more economical to use anthracite pieces in place of coke (equivalence ratio 0.8–1.0 kg/kg), in amounts of 70–90 kg/t of hot metal; this technology was developed by researchers at the Ukrainian National Metallurgical Academy, at the Nekrasov Institute of Ferrous Metallurgy, Ukrainian Academy of Sciences, and at Krivorozhstal’. In this technology, considerable economic savings are made possible by the reduction in coke consumption and cost of the hot metal, without additional capital expenditures. 相似文献
108.
Nikolai B. Gorev Inna F. Kodzhespirova Yury A. Kovalenko Evgeny N. Privalov Eugenio F. Prokhorov 《Microelectronics Journal》2001,32(12):979-982
The distribution of the electric field in planar film–substrate GaAs structures under backgating is considered. It is shown that backgating can make the film exhibit a long-length region of a low-gradient electric field exceeding the threshold of N-type negative differential mobility, the magnitude of negative differential mobility in this region being high enough. At values of the film doping density and film thickness typical of GaAs transferred-electron devices, this region can be as long as several tens of micrometers. The underlying physical mechanism is discussed. 相似文献
109.
110.
Vitaly Shubin Yury Shelygin Sergey Achkasov Oleg Sushkov Ilya Nazarov Alexey Ponomarenko Iuliia Alimova Anna Loginova Aleksey Tsukanov 《International journal of molecular sciences》2022,23(13)
The aim of this study was to determine the characteristics of Russian patients with microsatellite instability (MSI) tumors. MSI in the tumor was determined in 514 patients with colon cancer using PCR and subsequent fragment analysis for five markers (NR21, NR24, BAT25, BAT26, and NR27). In the presence of microsatellite instability, the mismatch repair (MMR) system genes were examined using the NGS and MLPA methods to establish the diagnosis of Lynch syndrome. The overall frequency of MSI tumors was 15%: at stage I—19% (9/48), at stage II—21% (44/213), at stage III—16% (26/160), and at stage IV—2% (2/93). Patients with MSI tumors differed in the age of diagnosis, tumor localization, time of cancer recurrence, and stage of the disease. The overall and disease-free survival of patients whose tumors had MSI status was higher than that of patients with microsatellite-stable status, p = 0.04 and p = 0.02, respectively. Analysis of overall and disease-free survival of patients with Lynch syndrome and patients with sporadic colon cancer, but with MSI status, did not reveal significant differences, p = 0.52 and p = 0.24, respectively. The age of patients with Lynch syndrome was significantly younger than that of patients with sporadic colon cancer whose tumors had MSI status (p < 0.001). 相似文献