全文获取类型
收费全文 | 1169篇 |
免费 | 8篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 87篇 |
金属工艺 | 14篇 |
机械仪表 | 6篇 |
建筑科学 | 4篇 |
能源动力 | 28篇 |
轻工业 | 12篇 |
水利工程 | 3篇 |
石油天然气 | 5篇 |
无线电 | 25篇 |
一般工业技术 | 92篇 |
冶金工业 | 865篇 |
自动化技术 | 34篇 |
出版年
2024年 | 2篇 |
2023年 | 2篇 |
2022年 | 13篇 |
2021年 | 6篇 |
2020年 | 17篇 |
2019年 | 6篇 |
2018年 | 15篇 |
2017年 | 13篇 |
2016年 | 16篇 |
2015年 | 5篇 |
2014年 | 15篇 |
2013年 | 20篇 |
2012年 | 16篇 |
2011年 | 20篇 |
2010年 | 6篇 |
2009年 | 14篇 |
2008年 | 16篇 |
2007年 | 11篇 |
2006年 | 11篇 |
2005年 | 14篇 |
2004年 | 10篇 |
2003年 | 9篇 |
2001年 | 2篇 |
2000年 | 5篇 |
1999年 | 24篇 |
1998年 | 239篇 |
1997年 | 149篇 |
1996年 | 104篇 |
1995年 | 50篇 |
1994年 | 35篇 |
1993年 | 50篇 |
1992年 | 5篇 |
1991年 | 15篇 |
1990年 | 5篇 |
1989年 | 14篇 |
1988年 | 17篇 |
1987年 | 9篇 |
1986年 | 16篇 |
1985年 | 19篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 12篇 |
1981年 | 8篇 |
1980年 | 9篇 |
1978年 | 3篇 |
1977年 | 28篇 |
1976年 | 91篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1178条查询结果,搜索用时 15 毫秒
21.
An anonymous questionnaire inquiry performed among 324 school teachers in the Randers area with the purpose of elucidating teachers' knowledge about asthma is presented. To a series of statements about asthma, the teachers should answer yes, no or don't know. A limited knowledge about asthma in children was found. The knowledge about medicamental treatment was particularly limited. Only 57 per cent knew that wheezing after physical exertion is a strong indicator of asthma. Only five per cent had received proper instruction. This latter group had a significantly better knowledge of medical treatment (p < 0.0001-0.05). It is recommended that instruction in children's diseases, especially asthma should be reintroduced in teachers' training colleges. 相似文献
22.
AIM: To examine the association of Epstein-Barr virus (EBV) with carcinoma of the ear. METHODS: Five non-keratinising squamous cell carcinomas and two undifferentiated carcinomas of the ear were examined. In situ hybridisation was used to localised EBV-encoded RNAs (EBER). Immunohistochemical methods to detect LMP-1 and EBNA2 were performed in the EBER positive cases. RESULTS: Two cases were EBER positive, including one non-keratinising and one undifferentiated carcinoma. Both showed identical morphology to those arising from the nasopharynx, with abundant lymphoid stroma. They were both negative for LMP-1 and EBNA2. CONCLUSIONS: EBV associated carcinoma with the morphology of lymphoepithelioma can also arise from the middle ear. 相似文献
23.
扫描笔是近年新兴的扫描产品,它又可以称为微型扫描仪或手刮式扫描笔,常见的扫描笔大小大约跟"折扇"差不多,甚者会更小。它最大的特点是携带方便,特别适合商务人士随身携带出差办公使用。一般购买它主要是用于扫描办公文件、身份证、名片或大型工程图等等。下面,小编带大家去深入了解扫描笔,让你能够知才善用。 相似文献
24.
25.
D. C. Agarwal S. Sarin K. Wadhwa R. Vishwakarma M. B. Deshmukh S. Kurian 《Journal of Failure Analysis and Prevention》2005,5(6):70-78
The work presented in Part 1 of this article showed that additions of magnesium chloride (MgCl2) to ammonia solutions reduced the tendency of ammonia-induced stress-corrosion cracking (SCC) initiation in a Cu-5%Ni alloy.
The present work was undertaken to study the SCC behavior of the test alloy exposed to ammonia in the presence of varying
concentrations of MgCl2. The exposure to MgCl2 additions reduced the severity of the ammonia-induced SCC. 相似文献
26.
Molecular cloning, expression, and characterization of a functional single-chain Fv antibody to the mycotoxin zearalenone 总被引:1,自引:0,他引:1
Q Yuan JR Clarke HR Zhou JE Linz JJ Pestka LP Hart 《Canadian Metallurgical Quarterly》1997,63(1):263-269
The heavy-chain and kappa light-chain variable region genes of an antizearalenone hybridoma cell line (2G3-6E3-2E2) were isolated by PCR and joined by a DNA linker encoding peptide (Gly4Ser)3 as a single-chain Fv (scFv) DNA fragment. The scFv DNA fragment was cloned into a phagemid (pCANTAB5E) and expressed as a fusion protein with E tag and phage M13 p3 in Escherichia coli TG1. In the presence of helper phage M13K07, the scFv fusion protein was displayed on the surfaces of recombinant phages. High-affinity scFv phages were enriched through affinity selection in microtiter wells coated with zearalenone-ovalbumin conjugate. The selected recombinant phages were used to infect E. coli HB2151 for the production of soluble scFv antibodies. One selected clone (pQY1.5) in HB2151 secreted a soluble scFv antibody (QY1.5) with a high zearalenone-binding affinity (concentration required for 50% inhibition of binding, 14 ng/ml), similar to that of parent monoclonal antibody in a competitive indirect enzyme-linked immunosorbent assay. However, scFv QY1.5 exhibited higher cross-reactivity with zearalenone analogs and had greater sensitivity to methanol destabilization than the parent monoclonal antibody did. Nucleotide sequence analyses revealed that the light-chain portion of scFv QY1.5 had a nucleotide sequence identity of 97% to a mouse germ line gene VK23.32 in mouse kappa light-chain variable region subgroup V, whereas the heavy-chain nucleotide sequence was classified as mouse heavy-chain subgroup III (D) but without any closely related members having highly homologous complementarity-determining region sequences. The potential of soluble scFv QY1.5 for routine screening of zearalenone and its analogs was demonstrated with zearalenone-spiked corn extracts. 相似文献
27.
P. R. Deshmukh S. N. Pusawale A. D. Jagadale C. D. Lokhande 《Journal of Materials Science》2012,47(3):1546-1553
The amorphous hydrous ruthenium oxide (RuO2·nH2O) thin films were deposited by a simple and inexpensive successive ionic layer adsorption and reaction (SILAR) method. These
films were characterized for their structural, surface morphological, and compositional study by means of X-ray diffraction
(XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and energy dispersive X-ray analysis
(EDAX) techniques. The wettability test was carried out by measuring the water contact angle. The scanning electron microscopy
study showed small RuO2 particles are grouped together to form porous agglomerates. The FT-IR study confirmed the formation of hydrous ruthenium
oxide films. The hydrophilic nature of ruthenium oxide (RuO2·nH2O) thin films was observed from water contact angle measurement. The presence of Ru and O in the film was confirmed by EDAX
analysis. The supercapacitor behavior of these films studied in 0.5 M H2SO4 electrolyte showed maximum specific capacitance of 162 F g−1 at 10 mV s−1 scan rate. These films exhibit 80% cycling performance after 2,000 cycles. The charge–discharge studies carried at 1 mA cm−2 current density revealed the specific power of 3.5 KW kg−1 and specific energy of 29.7 W Kg−1 with 93% coulombic efficiency. 相似文献
28.
Undoped and Ga doped ZnO thin films (1% GZO, 3% GZO and 5% GZO) were grown on c-Al2O3 substrates using the 1, 3 and 5 at. wt.% Ga doped ZnO targets by pulsed laser deposition. X-ray diffraction studies revealed that highly c-axis oriented, single phase, undoped and Ga doped ZnO thin films with wurtzite structure were deposited. Micro-Raman scattering analysis showed that Ga doping introduces defects in the host lattice. The E2High mode of ZnO in Ga doped ZnO thin film was observed to shift to higher wavenumber indicating the presence of residual compressive stress. Appearance of the normally Raman inactive B1 modes (B1Low, 2B1Low and B1High) due to breaking of local translational symmetry, also indicated that defects were introduced into the host lattice due to Ga incorporation. Band gap of the Ga doped ZnO thin films was observed to shift to higher energy with the increase in doping concentration and is explicated by the Burstein-Moss effect. Electrical resistivity measurements of the undoped and GZO thin films in the temperature range 50 to 300 K revealed the metal to semiconductor transition for 3 and 5% GZO thin films. 相似文献
29.
S.M. Deshmukh C.K. Ghatak P.R. Arya A. Subhananda Rao 《Journal of Energetic Materials》2013,31(4):321-331
In an attempt to replace toxic ingredients like lead ferrocyanide (LFCN) in electrical squibs, experiments were conducted by using barium ferrocyanide (BFCN) as an ingredient of squib composition. Electrothermal response (ETR), functional characteristics such as no-fire current (NFC) and all-fire current (AFC), were studied and compared with lead ferrocyanide-based squibs. Threshold firing currents were determined using the Bruceton staircase method. The squibs were also subjected to accelerated ageing and performance was evaluated. The results indicate better performance of barium ferrocyanide squibs to electrothermal response and a higher threshold no fire current, making it comparatively safe to handle as compared to lead ferrocyanide–based squibs. The results of accelerated ageing indicate a reasonable shelf life. ETR technique is found to be a good diagnostic tool for quality control. 相似文献
30.
The deposition of copper selenide(CuSe)thin films was carried out using liquid phase chemical bath deposition process at the optimized growth parameters as:60℃deposition temperature,90 minutes deposition time,pH equal to 10.5±0.1 and 72±2 r/min speed of mechanical rotation.The as-grown deposits exhibited excellent uniformity and physical adherency with the substrate surface and are smooth and diffusely reflecting with colour changing from yellowish orange to dark chocolate during deposition.The layer is of the order of 300 nm thick.The EDS analysis technique gave film composition to be nearly stoichiometric(Cu=47.89%,Se=52.11%).An X-ray diffraction analysis showed CuSe to be polycrystalline hexagonal with a good match of d-values and intensities of reflections.The crystallite size is in the nanorange(50-60 nm).The as-deposited CuSe exhibited a high coefficient of absorption(α=105cm-1)with a direct optical band gap of 1.81 eV.Compared to other chalcogenides,CuSe films exhibit low resistance;room temperature electrical resistivity being 1.55×103?cm.The electrical conductivity decreased with increase in temperature up to 473 K;showing totally unusual behaviour from that of the semiconducting property.The thermo probe measurements showed n-type conduction of the samples. 相似文献