全文获取类型
收费全文 | 1432篇 |
免费 | 72篇 |
专业分类
电工技术 | 23篇 |
综合类 | 2篇 |
化学工业 | 369篇 |
金属工艺 | 43篇 |
机械仪表 | 25篇 |
建筑科学 | 81篇 |
矿业工程 | 3篇 |
能源动力 | 55篇 |
轻工业 | 78篇 |
水利工程 | 11篇 |
石油天然气 | 2篇 |
无线电 | 92篇 |
一般工业技术 | 260篇 |
冶金工业 | 109篇 |
原子能技术 | 10篇 |
自动化技术 | 341篇 |
出版年
2023年 | 17篇 |
2022年 | 34篇 |
2021年 | 63篇 |
2020年 | 36篇 |
2019年 | 33篇 |
2018年 | 41篇 |
2017年 | 45篇 |
2016年 | 56篇 |
2015年 | 62篇 |
2014年 | 56篇 |
2013年 | 98篇 |
2012年 | 86篇 |
2011年 | 118篇 |
2010年 | 80篇 |
2009年 | 73篇 |
2008年 | 95篇 |
2007年 | 69篇 |
2006年 | 66篇 |
2005年 | 45篇 |
2004年 | 34篇 |
2003年 | 29篇 |
2002年 | 22篇 |
2001年 | 17篇 |
2000年 | 16篇 |
1999年 | 32篇 |
1998年 | 32篇 |
1997年 | 20篇 |
1996年 | 9篇 |
1995年 | 8篇 |
1994年 | 17篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1958年 | 2篇 |
排序方式: 共有1504条查询结果,搜索用时 203 毫秒
121.
Influence of shear flow on the preparation of polymer layered silicate nanocomposites 总被引:1,自引:0,他引:1
In this paper the influence of melt-processing on the final polymer/layered silicate nanocomposite morphology is discussed. In particular the role of shear forces on the transformation of the original large clay agglomerates is of interest. Several polymer nanocomposites were prepared by melt-extrusion, involving polycaprolactone, poly(ethylene oxide), polyamide-12 or polyamide-6 as the matrix polymer. The nanocomposite morphology was characterised by X-ray diffraction and transmission electron microscopy and the clay tactoid morphology with polarised optical microscopy and scanning electron microscopy. The development of the tactoid and nanocomposite morphology during melt-mixing under shear was studied time-resolved by optical microscopy in conjunction with a rheometer and synchrotron X-ray scattering together with a Couette type flow cell. The shear forces in the melt-preparation of polymer layered mineral nanocomposites facilitate the break-up of large-sized agglomerates, whereas the extent of further exfoliation of the mineral layers is determined by the compatibility between the polymer matrix and the mineral layers rather than by shear forces. 相似文献
122.
Sven Schmidbauer Jens Hahn Frank Jakubowski Yu-Wei Ting Jürgen Faul 《Microelectronic Engineering》2008,85(10):2037-2041
Novel dual work function (DWF) based transistors featuring low gate resistances are presented. The process discussed enables extremely fast array timings easily and is thus key to fulfilling the performance requirements for high performance DRAM chips. The key enabler of the advanced gate integration scheme and its properties is the understanding of tuning the interface contact resistance. The objective of this work was to systematically investigate the role of the interface between poly-Si and metal of DRAM gate structures focused on electrical data. Contact resistance values, speed and elemental analysis information summarize the main findings of the gate development and furthermore the stable control of the very thin film stack in high volume production. 相似文献
123.
124.
Synthesis of 2‐[18F]Fluoro‐2‐deoxyisosorbide 5‐mononitrate and Assessment of Its in vivo Biodistribution as Determined by Dynamic Positron Emission Tomography (PET)
下载免费PDF全文
![点击此处可从《ChemMedChem》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Nico Santschi Dr. Stefan Wagner Dr. Constantin Daniliuc Dr. Sven Hermann Prof. Dr. Michael Schäfers Prof. Dr. Ryan Gilmour 《ChemMedChem》2015,10(10):1724-1732
Herein we disclose the synthesis of 2‐fluoro‐2‐deoxyisosorbide 5‐mononitrate (2F‐IS‐5MN), a fluorinated analogue of the commonly prescribed vasodilator isosorbide 5‐mononitrate (IS‐5MN). X‐ray structural data for IS‐5MN and its C2‐epimeric congener IM‐5MN are presented together with structural data for 2F‐IS‐5MN. Radioisotope labeling of 2F‐IS‐5MN has, for the first time, allowed observation of the in vivo biodistribution of this organic nitrate by means of dynamic positron emission tomography (PET) in wild‐type mice. 相似文献
125.
Dr. Kornelia Hardes Dr. Gero L. Becker Dr. Yinghui Lu Dr. Sven O. Dahms Susanne Köhler Dr. Wolfgang Beyer Prof. Kirsten Sandvig Dr. Hiroyuki Yamamoto Prof. Iris Lindberg Lisa Walz Dr. Veronika von Messling Dr. Manuel E. Than Prof. Wolfgang Garten Prof. Torsten Steinmetzer 《ChemMedChem》2015,10(7):1218-1231
New peptidomimetic furin inhibitors with unnatural amino acid residues in the P3 position were synthesized. The most potent compound 4‐guanidinomethyl‐phenylacteyl‐Arg‐Tle‐Arg‐4‐amidinobenzylamide (MI‐1148) inhibits furin with a Ki value of 5.5 pM . The derivatives also strongly inhibit PC1/3, whereas PC2 is less affected. Selected inhibitors were tested in cell culture for antibacterial and antiviral activity against infectious agents known to be dependent on furin activity. A significant protective effect against anthrax and diphtheria toxin was observed in the presence of the furin inhibitors. Furthermore, the spread of the highly pathogenic H5N1 and H7N1 avian influenza viruses and propagation of canine distemper virus was strongly inhibited. Inhibitor MI‐1148 was crystallized in complex with human furin. Its N‐terminal guanidinomethyl group in the para position of the P5 phenyl ring occupies the same position as that found previously for a structurally related inhibitor containing this substitution in the meta position, thereby maintaining all of the important P5 interactions. Our results confirm that the inhibition of furin is a promising strategy for a short‐term treatment of acute infectious diseases. 相似文献
126.
Back Cover: Directed Divergent Evolution of a Thermostable D‐Tagatose Epimerase towards Improved Activity for Two Hexose Substrates (ChemBioChem 4/2015)
下载免费PDF全文
![点击此处可从《Chembiochem : a European journal of chemical biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
127.
Particularly in fast rolling mills, conventional actuators reach their dynamic limits, when longitudinal thickness variations of the incoming strip shall be reduced with high accuracy by model-predictive roll gap control. Accordingly, the applicability of highly dynamic piezoelectric actuators in combination with electromechanical spindles and a high frequency precision measurement of the thickness in front of the roll gap was examined. Rolling tests in a cold rolling mill for narrow slit strips show that this novel concept is suitable to provide the required dynamic actuation especially at high rolling speed. 相似文献
128.
Sven Hafner Vera A. Hartdegen Maximilian S. Hofmayer Thomas M. Klaptke 《Propellants, Explosives, Pyrotechnics》2016,41(5):806-813
Different carboxylic acid derivatives of 2,2‐dinitropropane‐1,3‐diol (DNPD) and 2,2‐bis(azidomethyl)propane‐1,3‐diol (BAMP) were synthesized to investigate their suitability as energetic plasticizers. The syntheses were carried out using acyl chlorides of acetic, propionic, and butyric acid. The obtained products were characterized by elemental analysis, NMR, and IR spectroscopy. The energetic properties of the synthesized compounds were calculated on the basis of the computed heats of formation at the CBS‐4M level of theory using the EXPLO5 version 6.02 computer code. Investigations of physical stabilities were carried out using BAM drop hammer and friction tester. Low and high temperature behavior was determined by differential scanning calorimetry (DSC). The energetic and physical properties of the synthesized compounds were compared to the literature known energetic plasticizers N‐butyl nitratoethylnitramine (BuNENA) and diethylene glycol bis(azidoacetate) ester (DEGBAA). For analyzing the plasticizing abilities, mixtures of glycidyl azide polymer (GAP) and poly(3‐nitratomethyl‐3‐methyloxetan) (polyNIMMO) were prepared with both propionyl based compounds in different ratios and investigated regarding their glass transition temperatures and viscosity. Both compounds showed plasticizing effects in the range of BuNENA. 相似文献
129.
Paul Sonntag Jan Haschke Sven Kühnapfel Tim Frijnts Daniel Amkreutz Bernd Rech 《Progress in Photovoltaics: Research and Applications》2016,24(5):716-724
We present an interdigitated back‐contact silicon heterojunction system designed for liquid‐phase crystallized thin‐film (~10 µm) silicon on glass. The preparation of the interdigitated emitter (a‐Si:H(p)) and absorber (a‐Si:H(n)) contact layers relies on the etch selectivity of doped amorphous silicon layers in alkaline solutions. The etch rates of a‐Si:H(n) and a‐Si:H(p) in 0.6% NaOH were determined and interdigitated back‐contact silicon heterojunction solar cells with two different metallizations, namely Al and ITO/Ag electrodes, were evaluated regarding electrical and optical properties. An additional random pyramid texture on the back side provides short‐circuit current density (jSC) of up to 30.3 mA/cm2 using the ITO/Ag metallization. The maximum efficiency of 10.5% is mainly limited by a low of fill factor of 57%. However, the high jSC, as well as VOC values of 633 mV and pseudo‐fill factors of 77%, underline the high potential of this approach. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
130.
Im Hinblick auf die Anforderungen an die Dämmung der Gebäudehülle hat sich ein Wechsel der Bezugsgrößen und Abhängigkeiten von der Energieeinsparverordnung (EnEV) 2007 zur EnEV 2009 vollzogen. Deshalb ist ein direkter Vergleich der beiden Vorschriften, zumindest bei Neubauten, nicht ohne weiteres möglich. Im folgenden Artikel wird die Möglichkeit eines allgemein gültigen Vergleichs der beiden Anforderungsniveaus untersucht. Daraus lassen sich für den Planer Schlüsse im Hinblick auf die Einhaltung der Anforderungen und deren Auswirkung auf den Entwurf und die Konstruktion ziehen. Abschnitt 1 behandelt dabei den Neubau von Wohngebäuden, Abschnitt 2 den Neubau von Nichtwohngebäuden und Abschnitt 3 die Bestandsgebäude. Comparison of the heat insulation requirements for building envelopes between EnEV 2007 and EnEV 2009. The heat insulation requirements for building envelopes depending on reference values and various conditions have been changed from EnEV 2007 (German Building Energy Conservation Ordinance) to EnEV 2009. Therefore, a direct comparison of both regulations is not possible, especially for new buildings. In this article the possibility of a generally valid comparison of both requirement levels is examined. Conclusions for the design of residential buildings, commercial buildings and refirbishment of existing buildings are given. 相似文献