全文获取类型
收费全文 | 1705篇 |
免费 | 41篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 93篇 |
综合类 | 1篇 |
化学工业 | 301篇 |
金属工艺 | 44篇 |
机械仪表 | 44篇 |
建筑科学 | 37篇 |
能源动力 | 61篇 |
轻工业 | 104篇 |
水利工程 | 5篇 |
石油天然气 | 8篇 |
无线电 | 251篇 |
一般工业技术 | 222篇 |
冶金工业 | 410篇 |
原子能技术 | 38篇 |
自动化技术 | 132篇 |
出版年
2023年 | 9篇 |
2022年 | 11篇 |
2021年 | 25篇 |
2020年 | 10篇 |
2019年 | 10篇 |
2018年 | 26篇 |
2017年 | 24篇 |
2016年 | 22篇 |
2015年 | 18篇 |
2014年 | 26篇 |
2013年 | 67篇 |
2012年 | 44篇 |
2011年 | 66篇 |
2010年 | 60篇 |
2009年 | 66篇 |
2008年 | 57篇 |
2007年 | 65篇 |
2006年 | 54篇 |
2005年 | 47篇 |
2004年 | 35篇 |
2003年 | 50篇 |
2002年 | 52篇 |
2001年 | 47篇 |
2000年 | 45篇 |
1999年 | 43篇 |
1998年 | 153篇 |
1997年 | 100篇 |
1996年 | 86篇 |
1995年 | 51篇 |
1994年 | 44篇 |
1993年 | 46篇 |
1992年 | 23篇 |
1991年 | 30篇 |
1990年 | 13篇 |
1989年 | 17篇 |
1988年 | 19篇 |
1987年 | 20篇 |
1986年 | 17篇 |
1985年 | 27篇 |
1984年 | 17篇 |
1983年 | 14篇 |
1982年 | 11篇 |
1981年 | 13篇 |
1980年 | 9篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1977年 | 12篇 |
1976年 | 15篇 |
1975年 | 8篇 |
1972年 | 6篇 |
排序方式: 共有1751条查询结果,搜索用时 738 毫秒
171.
172.
173.
Takehiro Takahashi Katsuyuki Shizu Kazunori Togashi 《Science and Technology of Advanced Materials》2014,15(3)
A new series of luminescent 1,4-diazatriphenylene (ATP) derivatives with various peripheral donor units, including phenoxazine, 9,9-dimethylacridane and 3-(diphenylamino)carbazole, is synthesized and characterized as thermally activated delayed fluorescence (TADF) emitters. The influence of the donor substituents on the electronic and photophysical properties of the materials is investigated by theoretical calculations and experimental spectroscopic measurements. These ATP-based molecules with donor–acceptor–donor (D–A–D) structures can reduce the singlet–triplet energy gap (0.04–0.26 eV) upon chemical modification of the ATP core, and thus exhibit obvious TADF characteristics in solution and doped thin films. As a demonstration of the potential of these materials, organic light-emitting diodes containing the D–A–D-structured ATP derivatives as emitters are fabricated and tested. External electroluminescence quantum efficiencies above 12% and 8% for green- and sky-blue-emitting devices, respectively, are achieved. 相似文献
174.
The recent success in the synthesis and total structure determination of atomically precise gold nanoparticles has provided exciting opportunities for fundamental studies as well as the development of new applications. These unique nanoparticles are of molecular purity and possess well defined formulas (i.e., specific numbers of metal atoms and ligands), resembling organic compounds. Crystallization of such molecularly pure nanoparticles into macroscopic single crystals allows for the determination of total structures of nanoparticles (i.e., the arrangement of metal core atoms and surface ligands) by X-ray crystallography. In this perspective article, we summarize recent efforts in doping and alloying gold nanoparticles with other metals, including Pd, Pt, Ag and Cu. With atomically precise gold nanoparticles, a specific number of foreign atoms (e.g., Pd, Pt) can be incorporated into the gold core, whereas a range of Ag and Cu substitutions is observed but, interestingly, the total number of metal atoms in the homogold nanoparticle is preserved. The heteroatom substitution of gold nanoparticles allows one to probe the optical, structural, and electronic properties truly at the single-atom level, and thus provides a wealth of information for understanding the intriguing properties of this new class of nanomaterials. 相似文献
175.
Hiromi Nakano Motohiro Yamada Masahiro Fukumoto Eiji Yamaguchi 《Journal of Thermal Spray Technology》2011,20(3):407-411
Cold spraying has been developed as a high-quality coating technique. In this article, copper is deposited on an AlN substrate
coated by the sputtering of titanium and copper at a low pressure of less than 1.0 MPa, making this approach suitable for
a wide range of engineering applications. In order to understand the adhesion mechanism at the atomic scale, the interfacial
regions are carefully observed in thin foil samples from the cross sections of the specimens with a HREM. We find a unique
wavy boundary between the sputtered titanium and the sputtered copper. It is assumed that the shear-instability phenomenon
occurs due to the cold-spraying process and influences the adhesive strength. Furthermore, the cold-sprayed copper particles
are connected directly without any oxidation layer due to the appearance of new metallic surfaces during the impact process.
The TEM data clearly reveal the phenomena and mechanisms related to the impact of powder sprayed on the substrate. 相似文献
176.
Michael Zeutzius Toshiaki Setoguchi Toshihiro Nakano Hideo Miyanishi Kunio Terao Saga University Honjo Saga - Japan 《热科学学报(英文版)》2000,(2)
~nonEmphasising time characterishcs and contIDI, onlyfew workll'v is av'ailable among the numerous reports onPulse combustors. Rare work deals with tWin Pulsecombustorsls] or combined pulse combustor-"dinesystemsl']. Kenffield15] obtained with a combinedconvenhonal Pulse combustor-tulbine system acombushon Pressals gain of 3-7% and a totalPerformance Of the combustor-"dine system for Pulsecombushon 40% higher than that of steady'combushonwhat aught also be due tO the brine characteristics.… 相似文献
177.
At the National Metrology Institute of Japan (NMIJ), the triple point of neon was measured using an NMIJ sealed cell, NMIJ Ne-5, and a modular sealed-cell model, Ec2Ne, made by the Istituto Nazionale di Ricerca Metrologica (INRiM) in Italy, and the results were compared. The melting curves obtained with the NMIJ Ne-5 cell show narrow widths (0.1 mK) over a wide range of the inverse of the melted fraction (1/F) from 1/F = 1 to 1/F = 10, which is consistent with a previous report. On the other hand, the width of the melting curves obtained with the Ec2Ne cell is 0.15 mK from 1/F = 1 to 1/F = 10. The liquidus point T tp estimated by the melting curves from F ~ 0.35 to F ~ 0.85 using the NMIJ cell is 0.05 mK higher than that using the Ec2Ne cell. The difference does not agree with the results obtained in an assay of the isotopic concentration from samples of the original Ne sources. The origin of the discrepancy has not been clarified yet. 相似文献
178.
Seiichi Kiyama Shingo Nakano Yoichi Domoto Hitoshi Hirano Hisaki Tarui Kenichiro Wakisaka Makoto Tanaka Shinya Tsuda Shoichi Nakano 《Solar Energy Materials & Solar Cells》1997,48(1-4)
This paper proposes a new advanced fabrication technology for a low-cost integrated-type a-Si solar cell. Integrated-type cells provide many advantages and have been industrialized with a laser patterning method. However, a higher throughput and more efficient patterning method was required for applying a-Si solar cells to a power generating system. Plasma CVM (Chemical Vaporization Machining) was first applied to advanced patterning because of its advantages of high speed and selectivity. In this method, a plasma generated under high pressure localizes near the wire electrode and concentrates reactive radicals. As a result, we achieved an etching rate of more than 1 μm/s and selective patterning of a 200 μm-wide a-Si layer in 1 s multiline patterning was also developed for large-area modules. 相似文献
179.
The structure of gas–liquid two‐phase flow is investigated in order to establish a reliable criterion for the development of disturbance waves and droplets considering the effects of liquid viscosity. The structure of the gas–liquid interface and the flow rate of droplets entrained in gas are measured simultaneously at five kinematic viscosities (1.0, 3.2, 9.9, 30, 70 mm2/s). The time‐series traces of liquid film thickness measured by five holdup probes reveal that the inception of disturbance waves occurs at a liquid Reynolds number of 200 or a non‐dimensional liquid film thickness of 6.5. It is also shown that droplets are generated before the inception of disturbance waves with increasing liquid kinematic viscosity at a liquid velocity of 0.02 to 0.03 m/s. As previously published criteria for the inception of droplets are found to be unsatisfactory, a new critical condition for droplet generation balancing the interfacial shear stress $τi$ with the wave height h and surface tension σ is proposed: $τih/σ=0.025$. This relation describes the action of shear force and surface tension on wave crests, and is notably independent of liquid viscosity. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(8): 529–541, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20176 相似文献
180.
A PCR assay for the detection of acetic acid-tolerant lactic acid bacteria in the genera of Lactobacillus and Pediococcus was developed in this study. Primers targeting the bacterial 16S rRNA gene were newly designed and used in this PCR assay. To determine the specificity of the assay, 56 different bacterial strains (of 33 genera), 2 fungi, 3 animals, and 4 plants were tested. Results were positive for most tested bacterial members of 16S rRNA gene-based phylogenetic groups (classified in the Lactobacillus casei and Pediococcus group), including Lactobacillus fructivorans, Lactobacillus brevis, Lactobacillus buchneri, Lactobacillus plantarum, and Lactobacillus paracasei. For all other bacterial strains and eukaryote tested, results were negative. Bacterial DNA for PCR was prepared with a simple procedure with the use of Chelex 100 resin from culture after growth in deMan Rogosa Sharpe broth (pH 6.0). To test this PCR assay for the monitoring of the acetic acid-tolerant lactic acid bacteria, L. fructivorans was inoculated into several acidic food as an indicator. Before the PCR, the inoculation of 10 to 50 CFU of bacteria per g of food was followed by a 28-h enrichment culture step, and the PCR assay allowed the detection of bacterial cells. Including the enrichment culture step, the entire PCR detection process can be completed within 30 h. 相似文献