全文获取类型
收费全文 | 3228篇 |
免费 | 195篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 64篇 |
综合类 | 1篇 |
化学工业 | 864篇 |
金属工艺 | 43篇 |
机械仪表 | 73篇 |
建筑科学 | 152篇 |
矿业工程 | 1篇 |
能源动力 | 101篇 |
轻工业 | 244篇 |
水利工程 | 10篇 |
石油天然气 | 3篇 |
武器工业 | 1篇 |
无线电 | 297篇 |
一般工业技术 | 585篇 |
冶金工业 | 137篇 |
原子能技术 | 28篇 |
自动化技术 | 823篇 |
出版年
2024年 | 5篇 |
2023年 | 41篇 |
2022年 | 132篇 |
2021年 | 150篇 |
2020年 | 76篇 |
2019年 | 89篇 |
2018年 | 99篇 |
2017年 | 92篇 |
2016年 | 144篇 |
2015年 | 113篇 |
2014年 | 147篇 |
2013年 | 221篇 |
2012年 | 202篇 |
2011年 | 230篇 |
2010年 | 194篇 |
2009年 | 192篇 |
2008年 | 179篇 |
2007年 | 167篇 |
2006年 | 120篇 |
2005年 | 96篇 |
2004年 | 118篇 |
2003年 | 98篇 |
2002年 | 64篇 |
2001年 | 52篇 |
2000年 | 43篇 |
1999年 | 35篇 |
1998年 | 28篇 |
1997年 | 25篇 |
1996年 | 35篇 |
1995年 | 27篇 |
1994年 | 26篇 |
1993年 | 20篇 |
1992年 | 21篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 11篇 |
1988年 | 5篇 |
1987年 | 14篇 |
1986年 | 7篇 |
1985年 | 16篇 |
1984年 | 17篇 |
1983年 | 11篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1975年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有3427条查询结果,搜索用时 15 毫秒
111.
Tatsuhiro Takahashi Helmut Münstedt Michele Modesti Paolo Colombo 《Journal of the European Ceramic Society》2001,21(16):2821-2828
Silicon oxycarbide (SiOC) ceramic foams, produced by the pyrolysis of a foamed blend of a methylsilicone preceramic polymer and polyurethane (PU) in a 1/1 wt.% ratio, exhibit excellent physical and mechanical properties. The proposed process allows to easily modify the density and morphology of the foams, making them suitable for several engineering applications. However, it has been shown that, due to residual carbon present in the oxycarbide phase after pyrolysis, the foams are subjected to an oxidation process that reduces their strength after high temperature exposure to air (12 h 1200°C). A modified process, employing the same silicone resin preceramic polymer but a much lower PU content (silicone resin/PU=5.25/1 wt.% ratio), has been developed and is reported in this paper. Microstructural investigations showed that carbon rich regions deriving from the decomposition of the polyurethane template are still present in the SiOC foam, but have a much smaller dimension than those found in foams with a higher PU content. Thermal gravimetric studies performed in air or oxygen showed that the low-PU containing ceramic foams display an excellent oxidation resistance, because the carbon-rich areas are embedded inside the struts or cell walls and are thus protected by the dense silicon oxycarbide matrix surrounding them. SiOC foams obtained with the novel process are capable to maintain their mechanical strength after oxidation treatments at 800 and 1200°C (12 h), while SiOC foams obtained with a higher amount of PU show about a 30% strength decrease after oxidation at 1200°C (12 h). 相似文献
112.
<正>德国的RWM公司正在完成为瑞典研制取代目前手榴弹的新型空爆手榴弹的工作。2010年2月,瑞典国防装备管理局将一项研制、鉴定和批量生产该手榴弹的合同授予RWM公司。鉴定工作预计2011年3月进行,首批交付工作预计2011年底 相似文献
113.
The promotive effects of cerium oxide on commercial three-way catalysts (TWCs) for purification of motor exhaust gases have been widely investigated in recent years. This work shows the cooperative effects of CeO2–Pd on the kinetics of CO oxidation over Pd/CeO2–ZrO2. Under reducing-to-moderately oxidizing conditions, a zero-order O2 pressure dependence is found which can be interpreted on the basis of a mechanism involving a reaction between CO adsorbed on Pd and surface oxygen from the support. The high oxygen-exchange capability of the CeO2–ZrO2 support, as determined from temperature-programmed reduction/oxygen uptake measurements is suggested as being responsible for such a catalytic behavior. 相似文献
114.
Poly[3-3′(vinylcarbazole)] (PVK) was synthetized with N-vinylcarbazole as monomer by oxidative polymerization with ferric chloride. The resulting polymer was then deposited on various solid supports by using Langmuir-Schaefer (LS) method. The pressure-area isotherm of PVK revealed the possibility of compact monolayer formation at air-water interface. Different layers of PVK were doped with iodine vapours. Both scanning probe microscopy and optical microscopy images indicated a good uniformity of the films. The morphology and the thickness of PVK films were investigated using atomic force microscopy. The voltammetric investigation of I2 doped PVK showed a distinctive electrochemical behaviour. The photoinduced charge transfer across a donor/acceptor (D/A) hybrid interface provided an effective method to study the photoelectrochemical properties of the composite LS films. 相似文献
115.
Maria?Antonietta BresciaEmail author Vincenzo?Mazzilli Angela?Sgaramella Stefano?Ghelli Francesco?Paolo Fanizzi Antonio?Sacco 《Journal of the American Oil Chemists' Society》2004,81(5):431-436
Characterization of the lipid fraction of raw cow and buffalo milk samples, collected in different breeding areas in Apulia,
a region of southern Italy, were performed by means of 1H NMR. The aim of this work was to establish whether FA composition data obtained by 1H NMR can be used in the differentiation of buffalo and cow milk samples according to species. A complete assignment of the
signals present in the spectrum was attempted by COSY, heteronuclear coherence spectra. Quantification of FA was carried out
by inserting the integrals of particular peaks in suitable calculations. Multivariate statistical analysis, conducted on the
results of the quantification, permitted buffalo and cow milks to be distinguished. 相似文献
116.
Soares Carlos R.J.; Gomide Fernanda I.C.; Ueda Eric K.M.; Bartolini Paolo 《Protein engineering, design & selection : PEDS》2003,16(12):1131-1138
The influence of different factors acting on Escherichia coliperiplasmic expression of recombinant human growth hormone (hGH)in shake flask cultures has been investigated. Bacterial vectorscontaining the phage 相似文献
117.
Ceramic Microtubes from Preceramic Polymers 总被引:2,自引:0,他引:2
Paolo Colombo § Katia Perini Enrico Bernardo Tiziano Capelletti Giorgio Maccagnan 《Journal of the American Ceramic Society》2003,86(6):1025-1027
A novel process for the production of ceramic microtubes involving the microextrusion of preceramic polymers was studied. Microtubes with a wide range of inner and outer diameters and several centimeters long were produced from two silicone resins. A coextrusion approach was also used to extend the forming capability of the technique. The addition of carbon black resulted in electrically conductive silicon oxycarbide (SiOC) ceramic microtubes. SiOC microtubes possessed a high bending strength, ranging from ∼30–1100 MPa. 相似文献
118.
Arianna Zanoni Cora Casiraghi Riccardo Po Paolo Biagini Mattia Sponchioni Davide Moscatelli 《大分子材料与工程》2023,308(1):2200443
Redispersible polymer powders (RDPPs), i.e., additives obtained from core–shell nanoparticles and commercialized in the form of a dry powder, find intensive application in the concrete industry. However, they are mainly produced from fossil resources. Therefore, the development of bio-based RDPPs is important to reduce the carbon footprint of these additives. In this work, two types of core–shell nanoparticles with a high percentage of bio-based content are synthesized and show to be good candidates as RDPPs. In the first case, up to 75% of bio-based content is obtained by combining lauryl acrylate, derived from coconut and palm kernel oil, as main core material, with isobornyl methacrylate, coming from pine resin, exploited to create the outer harder shell. In the second case, a degradable macromonomer obtained by the ring opening polymerization of lactide using 2-hydroxyethyl methacrylate as initiator is used as the core-forming monomer to obtain degradable RDPPs. In both cases, the particles are synthesized with a two-step emulsion polymerization process conducted in one pot and then spray-dried to obtain the RDPPs of interest. The morphology and redispersibility of the powders are characterized. Finally, their use as concrete additives is preliminarily assessed by evaluating their effect on changes in the surface morphologies of concrete specimens. 相似文献
119.
Dr. Antonella Di Pizio Dr. Antonio Laghezza Prof. Paolo Tortorella Dr. Mariangela Agamennone 《ChemMedChem》2013,8(9):1475-1482
Matrix metalloproteinases (MMPs) are zinc‐dependent enzymes involved in several pathological states. Among them, MMP‐2 is a relevant therapeutic target because of its role in cancer development and progression. Many MMP inhibitors (MMPIs) have been discovered over the last 30 years, and the majority of them contain a functional group that binds the zinc ion (zinc‐binding group; ZBG). Unfortunately, no MMPIs have reached the market yet, owing to toxic effects due to unselective interactions of the ZBG. The new generation of MMPIs that do not bind the zinc ion could overcome problems of selectivity and toxicity, but have so far been developed only for MMP‐8, ‐12, and ‐13. In this work, a virtual screening protocol was established by combining ligand‐ and structure‐based methods to identify non‐zinc‐binding MMP‐2 inhibitors using a new‐generation MMP‐8 inhibitor as a probe to find unexplored interactions in the MMP‐2 S1′ site. The screening allowed the identification of micromolar MMP‐2 inhibitors that putatively avoid binding the zinc ion, as demonstrated by docking calculations. The LIA model, built to correlate predicted and experimental binding energies of the identified non‐zinc‐binding MMP‐2 hits, underpins the reliability of the predicted docking poses. 相似文献
120.