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91.
Process conditions in X-ray lithography for the fabrication of devices with sub-micron feature sizes
This article describes the fabrication of polymer structures with lateral dimensions in the sub-micron regime using hard X-rays
(λc ≈ 0.4 nm) from the electron storage ring ANKA. Spincoated polymethylmethacrylate (PMMA) grades have been analyzed with respect
to development rates and contrast. The contrast has been determined to be constant over a wide dose regime but rapidly decreases
for dose values below 1 kJ/cm3. Films with a thickness from 2 to 11 μm have been patterned using a high resolution X-ray mask consisting of 2 μm thick gold
absorbers on a suspended 1 μm thick silicon nitride membrane. The fabrication of sub-micron X-ray lithography structures with
feature sizes down to 400 nm is confined by the mechanical parameters of the resist material and the process conditions. Surface
tension after development limits the achievable aspect ratio of isolated pillars and walls, depending on the actual resist
height. PMMA structures have been successfully used as template for electroplating of 1 μm thick gold to demonstrate the fabrication
capability of sub-micron scale metal parts. 相似文献
92.
This paper describes model experiments with liquid metals of low melting point as an important tool to investigate the flow structure and related transport processes in melt flows being relevant for metallurgical applications. Three examples have been selected to demonstrate the benefit of such experiments, namely the electromagnetic stirring of a metallic melt in a pool, the directional solidification of Al‐Si alloys under the influence of an electromagnetically driven flow and the behaviour of a liquid metal bubble plume if a vertically travelling field is applied. Results of flow measurements are presented and the relevance for metallurgical processes is discussed. 相似文献
93.
Eugene A Smirnov Maria A Meledina Alexey V Garshev Vitaly I Chelpanov Sven Frost Jan U Wieneke Mathias Ulbricht 《Polymer International》2013,62(5):836-841
Titania microspheres with narrow size distribution and diameters of about 1 µm were prepared and subsequently functionalized using surface‐initiated atom transfer radical polymerization (ATRP) of N‐isopropylacrylamide. The ATRP initiator was immobilized on the particle surface via acylation of surface hydroxyl groups with α‐bromoisobutyryl bromide. Subsequently, an established ATRP reaction system was used for the preparation of titania surface‐grafted poly(N‐isopropylacrylamide) (PNiPAAm). Characterization was performed with electron microscopies, X‐ray diffraction, infrared spectroscopy and dynamic light scattering. It was found that the particle size in aqueous dispersions changed reversibly with temperature as expected for a shell of PNiPAAm, a polymer with a lower critical solution temperature at 32 °C. This confirmed the successful preparation of functional, stimuli‐responsive TiO2 microparticles via a straightforward controlled surface‐initiated polymerization method. 相似文献
94.
Jon Brunvoll Björg N. Cyvin Sven J. Cyvin Edward C. Kirby Ivan Gutman 《Polycyclic Aromatic Compounds》2013,33(4):219-229
Abstract A fully-naphthalenoid system (or simply fully-naphthalenoid) is a benzenoid where all vertices can be covered by disjoint naphthalene units. Invariants of these systems are studied with special emphasis on the CnHs formulae. An extensive enumeration of fully-naphthalenoids by means of a computer program is reported. A detailed classification of the numbers includes the symmetry distribution and an enumeration of the CnHs isomers. The forms of the smallest fully-naphthalenoids are displayed together with their Kekulé structure counts. 相似文献
95.
96.
Ivan Gutman Sven J. Cyvin Vesna Petrović Aleksandar Teodorović 《Polycyclic Aromatic Compounds》2013,33(3):183-189
Abstract A fully-naphthalenoid hydrocarbon (FUN) is a benzenoid hydrocarbon whose all π-electrons can be (formally) grouped into disjoint naphthalene-units. The cyclic conjugation in FUNs is studied by means of the energy-effects of their various cycles. It is found that the dominant conjugation modes in FUNs are those involving the 6- and 10-membered cycles of the “full” naphthalene fragments. The cycles belonging to the “empty” domains of a FUN have significantly smaller energy-effects. 相似文献
97.
This chapter examines issues concerned with supporting managers and organizations with information and communication technologies
as they decide and act in turbulent and high-velocity environments. In particular, the chapter identifies five key tensions
in this context: (1) the tension between the need for quick decisions and the need for analytical decision processes; (2)
the tension involving managerial need for action and the need for the safest execution of decisions that may be bold and risky;
(3) the tension around empowering middle managers and management teams at various organizational levels in the midst of powerful
and impatient top executives; (4) the tension between programmed, quick-action learning loops and the increased requirement
for emergence and improvisation; and (5) the tension between expending effort to eliminate the digital divide with other organizations
versus finding expedient ways to communicate through heterogeneous digital infrastructures. Each of the tensions, and how
it can be managed, is illustrated through a case example. The chapter ends by suggesting that the management of these critical
tensions needs to be fused into the day-to-day fabric of management practices for decision support processes.
This article is part of the “Handbook on Decision Support Systems” edited by Frada Burstein and Clyde W. Holsapple (2008)
Springer. 相似文献
98.
Eight experiments tested the hypothesis that infants' word segmentation abilities are reducible to familiar sound-pattern parsing regardless of actual word boundaries. This hypothesis was disconfirmed. in experiments using the headturn preference procedure: 8.5-month-olds did not mis-segment a consonantvowel- consonant (CVQ word (e.g., dice) from passages containing the corresponding phonemic pattern across a word boundary (C#VC#; "cold ice"), but they segmented it when the word was really present ("roll dice"). However, they did not segment the real vowel-consonant (VC) word (ice in "cold ice") until 16 months. Yet, at that age, they still did not false alarm on the straddling CVC word. Thus, infants do not simply respond to recurring phonemic patterns. Instead, they are sensitive to both acoustic and allophonic cues to word boundaries. Moreover, there is a sizable developmental gap between consonant and vowel-initial word segmentation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
99.
Hans-Eberhard Zschau Sven Neve Michael Schütze Klaus Bethge 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2008,266(10):2441-2445
In the present work the oxidation resistance of fluorine treated technical TiAl-alloys was investigated. Single and double fluorine beam line implantation was found to improve the high temperature oxidation resistance of this class of materials with Al-contents higher than 40 at.%. Calculated and measured fluorine depth profiles were compared. It was shown that the alloying elements do not modify significantly the fluorine profile and do not disturb the halogen effect. After single and double fluorine implantation and for different oxidation stages (isothermal/thermocyclic conditions) the maximum of the fluorine profile was measured by PIGE (Proton Induced Gamma Emission). The fluorine maximum was found to be located at the metal/oxide interface. The time dependence of the fluorine profile was determined as well. Double implantation led to a slower growing alumina layer. In this case a F-reservoir is obtained and improves the long term oxidation resistance of TiAl-based alloys. 相似文献
100.