全文获取类型
收费全文 | 403篇 |
免费 | 16篇 |
专业分类
电工技术 | 7篇 |
化学工业 | 69篇 |
金属工艺 | 33篇 |
机械仪表 | 27篇 |
建筑科学 | 4篇 |
能源动力 | 24篇 |
轻工业 | 16篇 |
水利工程 | 1篇 |
无线电 | 29篇 |
一般工业技术 | 84篇 |
冶金工业 | 57篇 |
原子能技术 | 11篇 |
自动化技术 | 57篇 |
出版年
2023年 | 6篇 |
2022年 | 11篇 |
2021年 | 12篇 |
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 18篇 |
2017年 | 13篇 |
2016年 | 14篇 |
2015年 | 3篇 |
2014年 | 15篇 |
2013年 | 28篇 |
2012年 | 19篇 |
2011年 | 18篇 |
2010年 | 24篇 |
2009年 | 12篇 |
2008年 | 30篇 |
2007年 | 8篇 |
2006年 | 15篇 |
2005年 | 17篇 |
2004年 | 9篇 |
2003年 | 6篇 |
2002年 | 6篇 |
2001年 | 10篇 |
2000年 | 13篇 |
1999年 | 13篇 |
1998年 | 7篇 |
1997年 | 11篇 |
1996年 | 3篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有419条查询结果,搜索用时 15 毫秒
71.
Composite organic-inorganic nanoparticles (COINs) with chemically encoded optical signatures 总被引:1,自引:0,他引:1
To obtain a coding system for multiplex detection, we have developed a method to synthesize a new type of nanomaterial called composite organic-inorganic nanoparticles (COINs). The method allows the incorporation of a broad range of organic compounds into COINs to produce surface enhanced Raman scattering (SERS)-like spectra that are richer in variety than fluorescence-based signatures. Preliminary data suggest that COINs can be used as Raman tags for multiplex and ultrasensitive detection of biomolecules. 相似文献
72.
R. Vijay M. Nagini S. S. Sarma M. Ramakrishna A. V. Reddy G. Sundararajan 《Metallurgical and Materials Transactions A》2014,45(2):777-784
Bulk samples of pure iron and yttria dispersed iron with and without titanium (i.e., Fe, Fe-Y2O3, and Fe-Y2O3-Ti) were prepared by hot extrusion of high-energy ball-milled powders. An examination of the microstructure using TEM revealed that the addition of titanium resulted in the reduction of the dispersoid size with a concomitant increase in the volume fraction of the dispersoids. As a result, Fe-Y2O3-Ti exhibited a substantial increase in hardness and tensile properties as compared to Fe and Fe-Y2O3. The higher hardness and strength of Fe-Y2O3-Ti is shown to be due to the presence of finer and higher number density of Y-Ti-O complex oxides. Dynamic strain aging in the temperature range of 423 K to 573 K (150 °C to 300 °C) was observed in all the compositions studied. 相似文献
73.
The hydrogen attack of steel involves the formation of methane bubbles along the grain boundaries and their subsequent link-up
to form fissures. This paper presents a detailed model for the kinetics of growth of such methane bubbles. The model considers
two parallel processes which can control the growth—one involving the bubble growth by direct power-law creep and the other
involving combinations of surface diffusion, grain boundary diffusion and matrix accommodation processes. The proposed model
is more general and complete than the earlier ones and considers for the first time the possibility of bubble growth being
controlled by surface diffusion and accommodation processes. The predictions of the model are shown to compare well with the
experimental results obtained in our lab and with the literature data. The model also indicates the relative importance of
lower carbon activity and increased creep stength of steel to its hydrogen attack resistance. 相似文献
74.
Radoslavov P. Papadopoulos C. Govindan R. Estrin D. 《Networking, IEEE/ACM Transactions on》2004,12(3):469-482
One approach to achieving scalability in reliable multicast is to use a hierarchy. A hierarchy can be established at the application level, or by using router-assist. With router-assist we have more fine-grain control over the placement of error-recovery functionality, therefore, a hierarchy produced by assistance from the routers is expected to have better performance. In this paper, we test this hypothesis by comparing two schemes, one that uses an application-level hierarchy (ALH) and another that uses router-assisted hierarchy (RAH). Contrary to our expectations, we find that the qualitative performance of ALH is comparable to RAH. We do not model the overhead of creating the hierarchy nor the cost of adding router-assist to the network. Therefore, our conclusions inform rather than close the debate of which approach is better. 相似文献
75.
P.R. Sundararajan 《Polymer》2002,43(5):1691-1693
The crystalline morphology of poly(dimethylsiloxane) was studied using a scanning electron microscope equipped with a cold stage. Samples of two different molecular weights were used. In both cases, spherulitic morphology is seen, from −70 °C, with spherulites of about 100 μ in size. Small single crystals of about a micron in size are also seen, and these are attributed to the presence of cyclics. 相似文献
76.
Vuyelwa Ncapayi Neethu Ninan Thabang C. Lebepe Sundararajan Parani Aswathy Ravindran Girija Richard Bright Krasimir Vasilev Rodney Maluleke Ncediwe Tsolekile Tetsuya Kodama Oluwatobi S. Oluwafemi 《International journal of molecular sciences》2021,22(22)
The link between the microbiome and cancer has led researchers to search for a potential probe for intracellular targeting of bacteria and cancer. Herein, we developed near infrared-emitting ternary AgInSe/ZnS quantum dots (QDs) for dual bacterial and cancer imaging. Briefly, water-soluble AgInSe/ZnS QDs were synthesized in a commercial kitchen pressure cooker. The as-synthesized QDs exhibited a spherical shape with a particle diameter of 4.5 ± 0.5 nm, and they were brightly fluorescent with a photoluminescence maximum at 705 nm. The QDs showed low toxicity against mouse mammary carcinoma (FM3A-Luc), mouse colon carcinoma (C26), malignant fibrous histiocytoma-like (KM-Luc/GFP) and prostate cancer cells, a greater number of accumulations in Staphylococcus aureus, and good cellular uptake in prostate cancer cells. This work is an excellent step towards using ternary QDs for diagnostic and guided therapy for prostate cancer. 相似文献
77.
Dibyendu Chakravarty G. Sundararajan 《Journal of the European Ceramic Society》2013,33(13-14):2597-2607
The effect of addition of nanocrystalline ZrO2 and TiCN to ultrafine Al2O3 on mechanical properties and microstructure of the composites developed by spark plasma sintering (SPS) was investigated. The distribution of the nanoparticles was dependent on their overall concentration. Maximum hardness (21 GPa) and indentation toughness (5.5 MPa m1/2) was obtained with 23 vol% nanoparticles, which was considered as the optimum composition. The Zener pinning criteria were also satisfied at this composition with grain size of the restraining nanoparticles ~63–65 nm. Hardness of the composites follows the rule of mixtures; crack deflection and crack arrest by nanoparticles at grain boundaries along with mixed fracture mode led to high toughness in the nanocomposites. Cutting tool inserts were developed by SPS with the optimized composition and their machining performance was compared with commercial alumina based inserts. Increased toughness in the nanocomposite inserts reflects in the machining performance as the tool life improves drastically compared to that of the commercial inserts at high cutting speeds ≥500 m min?1. This was attributed to differences in their failure modes; the commercial inserts fail catastrophically by fracture due to their low toughness whereas the nanocomposite inserts reach the tool failure criteria by crater wear at all machining conditions. 相似文献
78.
Selvaraj Ranjith Priyan Govindan Suresh Kumar Srinivasan Surendhiran Mohd. Shkir 《International Journal of Applied Ceramic Technology》2023,20(5):2807-2816
Mesoporous silica nanoparticles with distinct characteristics like particle size, tunable pores, and high surface area have received much interest for environmental remediation, energy conversion, and biological applications. In this work, we synthesized spherical silica nanoparticles with tunable particle size and mesoporous properties using a low-cost silica source (rice husk) and polyethylene glycol (PEG) via microwave-assisted sol–gel synthesis. The formation of an amorphous silica structure was found using XRD and FTIR analysis. FESEM analysis showed that altering the PEG concentration from .01 to .005 M produced spherical silica nanoparticles with 100–500 nm in size. Nitrogen adsorption–desorption demonstrated that silica nanoparticles obtained with .005, .007, and .01 M of PEG had unique pore sizes and distributions, with specific surface areas of 51.475, 62.367, and 84.251 m2/g, respectively. These results might be due to PEG molecules’ capping effect, which acts as a soft template to regulate particle size, pore size, and dispersion by interacting with sodium silicate precursor. Hence, this approach can be a facile and cost-effective method to prepare mesoporous silica nanoparticles with controllable nanoscale characteristics for suitable applications. 相似文献
79.
I. Francis Cheng Yuqun Xie R. Allen Gonzales Przemys?aw R. Brejna Jency Pricilla Sundararajan B.A. Fouetio Kengne D. Eric Aston David N. McIlroy Jeremy D. Foutch Peter R. Griffiths 《Carbon》2011,(8):2852-2861
A new technique for the synthesis of large sheets (>10 cm2) of multi-layered graphene is presented. The condensation onto a heated surface (≈650 °C) of fumes from the thermal decomposition of asphalt in a ceramic crucible produces carbon films with a metallic sheen. Heating was done by a Fisher burner (natural gas/air) flame and the crucible was covered but exposed to laboratory atmosphere. These films were determined to be multi-layered graphene by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy (XPS), Raman and infrared spectroscopy and X-ray diffraction. XPS indicates that the films are primarily sp2 hybridized carbon with small amounts of sp3 C–H and C–O or C–N functionalities. Based on the D band shift (1593 cm−1) and the ratio of D band to G band (1354 cm−1) of 0.93, the Raman spectrum also indicates that the material is sp2 C with some nanocrystalline features. The infrared spectrum exhibits A1U (868 cm−1) and E1U (1599 cm−1) stretching of the intralayer bonds of graphene. This form of chemical vapor deposition may be a scalable to give much larger surface areas. Furthermore, the process does not require metal substrates. Deposition onto silica nanosprings and diatomites is demonstrated. 相似文献
80.
Balasubramani Govindaraj Pudupadi Sundararajan Muthusamy Sarojadevi 《Polymer International》2012,61(8):1344-1352
A series of functional polyhedral oligomeric silsesquioxane (POSS)/polyimide (PI) nanocomposites were prepared using a two‐step approach. First, octa(aminophenyl)silsesquioxane (OAPS) was mixed with poly(amic acid) (PAA) prepared by reacting bis(4‐amino‐3,5‐dimethylphenyl)‐3‐quinolylmethane and 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride. Second, the resulting solution was subjected to thermal imidization. The well‐defined ‘hard particles’ (POSS) and the strong covalent bonds in the amide linkage between the carbon atom of the carboxyl side group in PAA and the nitrogen atom of the amino group in POSS lead to a significant improvement in the thermal and mechanical properties. Homogeneous dispersion of POSS cages in the PI is evident from scanning electron microscopy, which further confirms that the POSS molecule becomes an integral part of the organic‐inorganic inter‐crosslinked network system. Differential scanning calorimetry and dynamic mechanical analysis show that the glass transition temperatures of the POSS‐containing nanocomposites are higher than that of the corresponding neat PI system, owing to the significant increase of the crosslinking density in the PI/POSS nanocomposites. Increasing the concentration of OAPS in the PI networks decreases the dielectric constant. Pure PI and PI/POSS systems have good antimicrobial activity. Copyright © 2011 Society of Chemical Industry 相似文献