全文获取类型
收费全文 | 2230篇 |
免费 | 99篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 28篇 |
综合类 | 4篇 |
化学工业 | 429篇 |
金属工艺 | 43篇 |
机械仪表 | 77篇 |
建筑科学 | 56篇 |
矿业工程 | 7篇 |
能源动力 | 250篇 |
轻工业 | 206篇 |
水利工程 | 21篇 |
石油天然气 | 13篇 |
无线电 | 313篇 |
一般工业技术 | 473篇 |
冶金工业 | 111篇 |
原子能技术 | 27篇 |
自动化技术 | 277篇 |
出版年
2024年 | 7篇 |
2023年 | 36篇 |
2022年 | 67篇 |
2021年 | 77篇 |
2020年 | 95篇 |
2019年 | 66篇 |
2018年 | 100篇 |
2017年 | 87篇 |
2016年 | 86篇 |
2015年 | 57篇 |
2014年 | 72篇 |
2013年 | 199篇 |
2012年 | 112篇 |
2011年 | 148篇 |
2010年 | 106篇 |
2009年 | 130篇 |
2008年 | 101篇 |
2007年 | 81篇 |
2006年 | 58篇 |
2005年 | 37篇 |
2004年 | 48篇 |
2003年 | 45篇 |
2002年 | 26篇 |
2001年 | 13篇 |
2000年 | 12篇 |
1999年 | 13篇 |
1998年 | 24篇 |
1997年 | 28篇 |
1996年 | 22篇 |
1995年 | 20篇 |
1994年 | 24篇 |
1993年 | 28篇 |
1992年 | 22篇 |
1991年 | 26篇 |
1990年 | 9篇 |
1989年 | 19篇 |
1988年 | 15篇 |
1987年 | 13篇 |
1986年 | 22篇 |
1985年 | 34篇 |
1984年 | 32篇 |
1983年 | 35篇 |
1982年 | 15篇 |
1981年 | 18篇 |
1980年 | 15篇 |
1979年 | 10篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1971年 | 4篇 |
排序方式: 共有2335条查询结果,搜索用时 15 毫秒
101.
Shiro Nishiwaki Andreas Burn Stephan Buecheler Martin Muralt Snke Pilz Valerio Romano Reiner Witte Lukas Krainer Gabriel J. Spühler Ayodhya N. Tiwari 《Progress in Photovoltaics: Research and Applications》2015,23(12):1908-1915
Monolithically integrated Cu(In,Ga)Se2 mini‐modules were fabricated in order to reduce the width of patterning related dead area. The Cu(In,Ga)Se2 layers were prepared on soda‐lime glasses using the multistage process at low substrate temperature below 500 °C. A picosecond laser with a wavelength of 532 nm was used for all of the structuring processes (P1, P2, and P3) for the monolithic integration. A “lift‐off” type structuring was applied for P1 and P3, and an “ablation” type was for P2. The laser structuring was optimized to be minimizing the dead area width, and the width of about 70 µm was successfully achieved. A mini‐module, in which the optimized structuring processes were applied for the integration, demonstrated a certified efficiency of 16.6%. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
102.
In this communication, a thermal analysis of concentrator-assisted solar distillation unit has been developed to optimize the glass cover inclination. The thermal energy is based on the energy balance equation for each component of the distillation unit by incorporating the proposed modified Dunckle's relation for internal heat loss. An analytical expression for various parameters, namely the water and glass cover temperatures, hourly and daily yield and an instantaneous thermal efficiency, has been derived. Numerical computations have been carried out and it has been observed that the daily output increases with inclination. 相似文献
103.
In this article, we report the influence of organic modifier structure (alkyl chain length C8-C20, single vs ditallow) and thereby, the effect of hydrophobicity on the structure, thermal and mechanical properties of poly(methyl methacrylate) (PMMA)-clay hybrids. Melt processed PMMA-clay hybrids were characterized using wide-angle X-ray diffraction, transmission electron microscopy, and differential scanning calorimetry. The organoclays having an alkyl chain length of more than 12 CH2 groups resulted in the formation of nanocomposites. The glass transition temperature (Tg) of PMMA increased in the presence of clay. The mean-field lattice model was used to predict the free energy for nanocomposite formation, which showed a reasonable match with the experimental results and provided a general guideline for the proper selection of polymer and organoclay (ie, organic modifier) to obtain nanocomposite. Tensile modulus showed maximum improvement of 58% for the nanocomposites compared to 9% improvement for the composites. Tensile modulus increased with increases in the alkyl chain length of the organic modifier and clay loading. The level of improvement for the tensile properties of nanocomposites prepared from primary and secondary ammonium-modified clay is the same as that obtained with the commercial organoclays. 相似文献
104.
An experimental study is carried out to quantitatively assess the dispersion quality of carbon nanotubes (CNTs) in epoxy matrix as a function of CNT variant and weight fraction. To this end, two weight fractions (0.05% and 0.25%) of as-grown, oxidized, and functionalized CNTs are used to process CNT/epoxy nanocomposites. Scanning electron microscopy, X-ray diffraction, and Fourier transform infrared analysis of different variants of CNTs are used to establish the efficiency of purification route. While the relative change in mechanical properties is investigated through tensile and micro-hardness testing, thermal conductivity of different nanocomposites is measured to characterize the effect of CNT addition on the average thermal properties of epoxy. Later on, a quantitative analysis is carried out to establish the relationship between the observed improvements in average composite properties with the dispersion quality of CNTs in epoxy. It is shown that carboxylic (-COOH) functionalization reduces the average CNT agglomerate size and thus ensures better dispersion of CNTs in epoxy even at higher CNT weight fraction. The improved dispersion leads to enhanced interfacial interaction at the CNT/epoxy interface and hence provides higher relative improvement in nanocomposite properties compared to the samples prepared using as-grown and oxidized CNTs. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48879. 相似文献
105.
Kiran Tiwari Rudramani Singh Vinai Kumar Singh Manoj Kumar Krishnamoorthi S. Kumar Krishna 《Iranian Polymer Journal》2020,29(7):615-623
Iranian Polymer Journal - In our recent work, we have reported on hydrogels devoid of cross-linkers. After observing the successful swelling and water retention properties, we have introduced... 相似文献
106.
Pierre C. Dagher Takashi Hato Henry E. Mang Zoya Plotkin Quentin V. Richardson Michael Massad Erik Mai Sarah E. Kuehl Paige Graham Rakesh Kumar Timothy A. Sutton 《International journal of molecular sciences》2016,17(5)
The development of chronic kidney disease (CKD) following an episode of acute kidney injury (AKI) is an increasingly recognized clinical problem. Inhibition of toll-like receptor 4 (TLR4) protects renal function in animal models of AKI and has become a viable therapeutic strategy in AKI. However, the impact of TLR4 inhibition on the chronic sequelae of AKI is unknown. Consequently, we examined the chronic effects of TLR4 inhibition in a model of ischemic AKI. Mice with a TLR4-deletion on a C57BL/6 background and wild-type (WT) background control mice (C57BL/6) were subjected to bilateral renal artery clamping for 19 min and reperfusion for up to 6 weeks. Despite the acute protective effect of TLR4 inhibition on renal function (serum creatinine 1.6 ± 0.4 mg/dL TLR4-deletion vs. 2.8 ± 0.3 mg/dL·WT) and rates of tubular apoptosis following ischemic AKI, we found no difference in neutrophil or macrophage infiltration. Furthermore, we observed significant protection from microvascular rarefaction at six weeks following injury with TLR4-deletion, but this did not alter development of fibrosis. In conclusion, we validate the acute protective effect of TLR4 signal inhibition in AKI but demonstrate that this protective effect does not mitigate the sequential fibrogenic response in this model of ischemic AKI. 相似文献
107.
Acrylonitrile–butadiene–styrene (ABS)–clay composite and intercalated nanocomposites were prepared by melt processing, using Na‐montmorillonite (MMT), several chemically different organically modified MMT (OMMT) and Na‐laponite clays. The polymer–clay hybrids were characterized by WAXD, TEM, DSC, TGA, tensile, and impact tests. Intercalated nanocomposites are formed with organoclays, a composite is obtained with unmodified MMT, and the nanocomposite based on synthetic laponite is almost exfoliated. An unintercalated nanocomposite is formed by one of the organically modified clays, with similar overall stack dispersion as compared to the intercalated nanocomposites. Tg of ABS is unaffected by incorporation of the silicate filler in its matrix upto 4 wt % loading for different aspect ratios and organic modifications. A significant improvement in the onset of thermal decomposition (40–44°C at 4 wt % organoclay) is seen. The Young's modulus shows improvement, the elongation‐at‐break shows reduction, and the tensile strength shows improvement. Notched and unnotched impact strength of the intercalated MMT nanocomposites is lower as compared to that of ABS matrix. However, laponite and overexchanged organomontmorillonite clay lead to improvement in ductility. For the MMT clays, the Young's modulus (E) correlates with the intercalation change in organoclay interlayer separation (Δd001) as influenced by the chemistry of the modifier. Although ABS‐laponite composites are exfoliated, the intercalated OMMT‐based nanocomposites show greater improvement in modulus. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
108.
In this article a thermal model has been developed to determine the convective mass transfer for different Grashof Number range in solar distillatiOn process. The model is based on simple regression analysis. Based on the experimental data obtained from the rigorous outdoor experimentation on passive and active distillation systems for summer climatic conditions, the values of C and n have been calculated. The modified values of C and n for Nu=C(GrPr)n, are proposed as C=0.0322; N=0.4114 for 1.794 × 1066 in a passive solar still and C=0.0538; N=0.383 for 5.498 × 1066 in an active solar still. The percentage deviation between experimental and theoretical results are found within an accuracy of 12%. 相似文献
109.
C. S. Naveen P. Raghu H. M. Mahesh K. Narasimha Rao R. Rakesh Kumar A. R. Phani 《稀有金属(英文版)》2014,33(5):578-582
TiO2thin films with 0.2 wt%, 0.4 wt%, 0.6wt%, and 0.8 wt% Fe were prepared on glass and silicon substrates using sol–gel spin coating technique. The optical cut-off points are increasingly red-shifted and the absorption edge is shifted over the higher wavelength region with Fe content increasing. As Fe content increases, the optical band gap decreases from 3.03 to 2.48 eV whereas the tail width increases from 0.26 to 1.43 eV. The X-ray diffraction(XRD) patterns for doped films at 0.2 wt% and0.8 wt% Fe reveal no characteristic peaks, indicating that the film is amorphous whereas undoped TiO2exhibits(101) orientation with anatase phase. Thin films of higher Fe content exhibit a homogeneous, uniform, and nanostructured highly porous shell morphology. 相似文献
110.
Oil/Water Separation: Table Salt as a Template to Prepare Reusable Porous PVDF–MWCNT Foam for Separation of Immiscible Oils/Organic Solvents and Corrosive Aqueous Solutions (Adv. Funct. Mater. 41/2017) 下载免费PDF全文