全文获取类型
收费全文 | 1127篇 |
免费 | 73篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 6篇 |
综合类 | 2篇 |
化学工业 | 526篇 |
金属工艺 | 8篇 |
机械仪表 | 17篇 |
建筑科学 | 50篇 |
矿业工程 | 1篇 |
能源动力 | 45篇 |
轻工业 | 140篇 |
水利工程 | 9篇 |
石油天然气 | 10篇 |
无线电 | 58篇 |
一般工业技术 | 163篇 |
冶金工业 | 60篇 |
原子能技术 | 3篇 |
自动化技术 | 103篇 |
出版年
2024年 | 1篇 |
2023年 | 27篇 |
2022年 | 167篇 |
2021年 | 129篇 |
2020年 | 50篇 |
2019年 | 47篇 |
2018年 | 42篇 |
2017年 | 43篇 |
2016年 | 49篇 |
2015年 | 36篇 |
2014年 | 55篇 |
2013年 | 75篇 |
2012年 | 85篇 |
2011年 | 62篇 |
2010年 | 42篇 |
2009年 | 53篇 |
2008年 | 48篇 |
2007年 | 23篇 |
2006年 | 22篇 |
2005年 | 18篇 |
2004年 | 16篇 |
2003年 | 9篇 |
2002年 | 12篇 |
2001年 | 7篇 |
2000年 | 9篇 |
1999年 | 5篇 |
1998年 | 12篇 |
1997年 | 11篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1974年 | 1篇 |
排序方式: 共有1201条查询结果,搜索用时 15 毫秒
101.
Monika Kova
evi Dora Markulin Matea Zelenika Marko Marjanovi Marija Lovri Denis Polan
ec Marina Ivan
i Jasna Mrv
i Kreimir Mol
anov Valentina Milainovi Sun
ica Roca Ivan Kodrin Lidija Barii 《International journal of molecular sciences》2022,23(20)
Considering the enormous importance of protein turns as participants in various biological events, such as protein–protein interactions, great efforts have been made to develop their conformationally and proteolytically stable mimetics. Ferrocene-1,1′-diamine was previously shown to nucleate the stable turn structures in peptides prepared by conjugation with Ala (III) and Ala–Pro (VI). Here, we prepared the homochiral conjugates of ferrocene-1,1′-diamine with l-/d-Phe (32/35), l-/d-Val (33/36), and l-/d-Leu (34/37) to investigate (1) whether the organometallic template induces the turn structure upon conjugation with amino acids, and (2) whether the bulky or branched side chains of Phe, Val, and Leu affect hydrogen bonding. Detailed spectroscopic (IR, NMR, CD), X-ray, and DFT studies revealed the presence of two simultaneous 10-membered interstrand hydrogen bonds, i.e., two simultaneous β-turns in goal compounds. A preliminary biological evaluation of d-Leu conjugate 37 showed its modest potential to induce cell cycle arrest in the G0/G1 phase in the HeLa cell line but these results need further investigation. 相似文献
102.
A novel batch plant for supercritical CO2 applications is proposed which is not equipped with expensive components, such as high‐pressure pumps, making it particularly suitable for bench‐scale use. For the first time, the use of a hanging scale is suggested to weigh the amount of CO2 required for the experiment and the use of the thermodynamics to reach the working conditions. The rig is able to cover different applications, e.g., aerogel drying, impregnation, and extraction, showing high flexibility. An approximate cost analysis has been performed considering as a reference a 150‐mL vessel. It has been calculated that both the setup and running costs are considerably lower than the common batch and semicontinuous rigs. 相似文献
103.
Preethi Balasubramanian Teresa Büttner Valentina Miguez Pacheco Aldo R. Boccaccini 《Journal of the European Ceramic Society》2018,38(3):855-869
Boron is considered to influence the performance of several metabolic enzymes and boron deficiency is associated with impaired growth and abnormal bone development. As such, boron is a beneficial bioactive element for animals and humans. It is also well known that boron stimulates wound healing and improves bone health. The addition of boron in different proportions to bioactive glasses has significant effects on glass structure, glass processing parameters, biodegradability, biocompatibility, bioactivity and cytotoxicity. Different compositions of bioactive glasses (BGs) containing boron, including boron-doped, borosilicate and borate glasses, are being investigated for bone and soft tissue engineering under the premise that these BGs are suitable carriers of boron, indicating controlled release of B species in the biological environment. This paper reviews up to date research and applications of borate, borosilicate, and boron doped silicate and phosphate BGs focussing on their physical, structural, degradation and biological properties for hard and soft tissue regeneration. 相似文献
104.
Liga Stipniece Valentina Stepanova Inga Narkevica Kristine Salma-Ancane Adrian R. Boyd 《Journal of the European Ceramic Society》2018,38(2):761-768
Mg-substituted hydroxyapatite (HAp) bioceramic microspheres were prepared by spray drying and subsequent processing at 1173, 1273 and 1373 K. Influence of various Mg substitution levels (up to 0.84 ± 0.10 wt%) on physicochemical properties of the HAp bioceramic microspheres was evaluated. Obtained results were used for the elucidation of the compositional and structural characteristics of the microspheres in conjunction with adsorption of protein, namely, bovine serum albumin (BSA). The primary difference among the microspheres processed at various temperature was the presence or absence of the micropores (<2 nm in diameter) and mesopores (between 2 and 50 nm). Presence of the micro- and mesopores resulted in higher specific surface area (SSA), enhanced solubility, i.e., ion release, and, accordingly, increase in the amount of BSA adsorbed on the microspheres. Furthermore, the BSA adsorption capacity of the microspheres decreased with increasing Mg content despite of higher SSA. 相似文献
105.
Permaglas ME771 is a glass-epoxy laminate which is suitable for use at cryogenic temperatures. We have measured the thermal conductivity of a sample of this material between 64 mK and 4.2 K in the direction parallel to the reinforcing fibres, enabling us to make a comparison with the better known material G-10CR. The thermal conductivity follows the form that would be expected for such a material, and is similar to that of G-10CR, which has a similar (room temperature) tensile strength. We comment on some confusion that has arisen over the difference between G-10CR, a material specifically produced for cryogenic use, and G-10, the more common equivalent. 相似文献
106.
Model-Supported Impact Assessment for the Water Sector in Central Germany Under Climate Change—A Case Study 总被引:1,自引:0,他引:1
Fred Fokko Hattermann Mathias Weiland Shaochun Huang Valentina Krysanova Zbigniew W. Kundzewicz 《Water Resources Management》2011,25(13):3113-3134
Climate change challenges water managers and researchers to find sustainable management solutions, in order to avoid undesirable
impacts on water resources, environment and water-dependent sectors. Needed are projections into the future for the main driving
forces, the resulting pressures on water resources, and quantification of the impacts. Modeling studies can play an important
role in investigating, quantifying, and communicating possible impacts of climate change, with account of uncertainty of the
results. However, climate change related impacts and a need for adaptation still play a minor role in current river basin
management plans that have to comply e.g. with the EU Water Framework Directive (WFD). One important reason is that climate
impact assessment is generally done in research institutes, while management plans are designed by practitioners working in
national and regional environmental agencies and water supply companies. Knowledge transfer from science to practice and visa
versa is often missing. In the present study, we propose a methodology and a case study for model-supported decision making
in the water sector applicable to a participatory water resources planning process. The methodology is applied in a case study
investigating climate change impacts on water resources. The case study area is the German State of Saxony-Anhalt, where the
task was to develop a climate change impact assessment including possible adaptation measures as basis for a federal adaptation
directive. 相似文献
107.
Nicoletta Sinelli Lorenzo Cerretani Valentina Di Egidio Alessandra Bendini Ernestina Casiraghi 《Food research international (Ottawa, Ont.)》2010,43(1):369-375
A sensory analysis of 112 virgin olive oils was performed by a fully trained taste panel. The samples were divided in “defective” and “not defective” on the basis of their olfactory attributes. Then, the “not defective” samples were classified into “low”, “medium” and “high” according to the fruity aroma intensity perceived by assessors. All samples were also analysed by FT-NIR and FT-IR spectroscopy and processed by classification methods (LDA and SIMCA). The results showed that NIR and MIR spectroscopy coupled with statistical methods are an interesting technique compared with traditional sensory assessment in classifying olive oil samples on the basis of the fruity attribute. The prediction rate varied between 71.6% and 100%, as average value. The spectroscopic methods, combined with chemometric strategies, could represent a reliable, cheap and fast classification tool, able to draw a complete fingerprint of a food product, describing its intrinsic quality attributes, that include its sensory attributes. 相似文献
108.
Anna Bernasconi Valentina Ciriani Fabrizio Luccio Linda Pagli 《Theory of Computing Systems》2008,42(4):450-464
Autosymmetric functions exhibit a special type of regularity that can speed-up the minimization process. Based on this autosymmetry,
we propose a three level form of logic synthesis, called ORAX (EXOR-AND-OR), to be compared with the standard minimal SOP
(Sum of Products) form.
First we provide a fast ORAX minimization algorithm for autosymmetric functions. The ORAX network for a function f has a first level of at most 2(n−k) EXOR gates, followed by the AND-OR levels, where n is the number of input variables and k is the “autosymmetry degree” of f. In general a minimal ORAX form has smaller size than a standard minimal SOP form for the same function. We show how the
gain in area of ORAX over SOP can be measured without explicitly generating the latter. If preferred, a SOP expression can
be directly derived from the corresponding ORAX. A set of experimental results confirms that the ORAX form is generally more
compact than the SOP form, and its synthesis is much faster than classical three-level logic minimization. Indeed ORAX and
SOP minimization times are often comparable, and in some cases ORAX synthesis is even faster. 相似文献
109.
U. Amato G. Amodeo V. Brandi V. Cuomo D. Ruggi C. Serio V. Silvestrini G. C. Tosato 《国际能源研究杂志》1987,11(1):45-68
Using a multiperiodal LP model (MARKAL) the authors assessed the likely potential of solar thermal and biogas systems under various circumstances. The study covered the period 1980–2005, in five segments of five years. It focused only on the subsystem of the energy end-uses which can be substituted for by solar and biogas technologies. In this paper we show the main results of the study regarding the competitiveness of the single solar and biogas technologies in different scenarios and their sensitivity to incentives and prices, together with the essential technical data regarding demand and supply technologies which produced those results. The analysis performed of the potential penetration of renewable technologies into the Italian energy system shows that their contribution will remain very marginal if the price of conventional energy carriers remains constant in constant money. However, the objective of removing with renewable technologies 1.5 per cent of the total Italian energy consumption appears to be realistic in the short-medium term. 相似文献
110.
Kane M.G. Campi J. Hammond M.S. Cuomo F.P. Greening B. Sheraw C.D. Nichols J.A. Gundlach D.J. Huang J.R. Kuo C.C. Jia L. Klauk H. Jackson T.N. 《Electron Device Letters, IEEE》2000,21(11):534-536
We have fabricated and characterized analog and digital circuits using organic thin-film transistors on polyester film substrates. These are the first reported dynamic results for organic circuits fabricated on polyester substrates. The high-performance pentacene transistors yield circuits with the highest reported clock frequencies for organic circuits 相似文献