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91.
92.
Georg Lausen 《Information Systems》1983,8(4):291-301
Formal aspects of optimistic concurrency control in a multiple version database system are discussed. It is distinguished between element-optimistic and set-optimistic methods. In an element-optimistic method the unit of scheduling for the concurrency control is one action/transaction, while in a set-optimistic method a set of transactions is scheduled. The underlying decision problems of serializability are defined and shown to be NP-complete in a model, which is typical for most modern transaction oriented database management systems. Therefore it is most probable, that both optimistic concurrency control types cannot be implemented efficiently in the general case. 相似文献
93.
Structural Superplasticity at High Strain Rates of Super Duplex Stainless Steel Fe‐25Cr‐7Ni‐3Mo‐0.3N
The fine‐grained super duplex stainless steel Fe‐25Cr‐7Ni‐3Mo‐0.3N consisting of two phases (δ‐ferrite/austenite) exhibits structural super‐plasticity at higher strain rates of ? ≈ 10?2s?1 in the temperature range between 975 and 1100°C. The equiaxed microstructure with an average grain size of was produced by thermomechanical processing. Maximum strain‐rate‐sensitivity exponents of m ≈ 0.5 and elongations to failure of more than 500% were achieved. From thermal activation analysis an activation energy for superplastic flow of Q = 310 ± 20 kJ/mole was derived. The superplastic behaviour at higher strain rates is quantitatively described by a deformation model where grain or interphase boundary sliding is accommodated by sequential steps of dislocation glide and climb. The high strain‐rate‐sensitivity exponent and the observed dislocation density indicate that dislocation climb in the slightly solid solution strengthened austenite is the rate controlling step for superplastic flow. The deformation mechanism reveals that the investigated super duplex stainless steel exhibits superplastic behaviour that is typical for class II solid solution alloys. 相似文献
94.
Schwaighofer A Tresp V Mayer P Krause A Beuthan J Rost H Metzger G Müller GA Scheel AK 《IEEE transactions on bio-medical engineering》2003,50(3):375-382
We describe a classification system for a novel imaging method for arthritic finger joints. The basis of this system is a laser imaging technique which is sensitive to the optical characteristics of finger joint tissue. From the laser images acquired at baseline and follow-up, finger joints can automatically be classified according to whether the inflammatory status has improved or worsened. To perform the classification task, various linear and kernel-based systems were implemented and their performances were compared. Based on the results presented in this paper, we conclude that the laser-based imaging permits a reliable classification of pathological finger joints, making it a sensitive method for detecting arthritic changes. 相似文献
95.
96.
Jakob PM Wang T Schultz G Hebestreit H Hebestreit A Elfeber M Hahn D Haase A 《Magma (New York, N.Y.)》2002,15(1-3):10-17
The unique characteristics of the human lung arising from low proton density and multiple air-tissue interfaces of the alveoli
cause difficulty in1H lung magnetic resonance imaging. In addition, the dominating signal from sources such as the thoracic muscle and subcutaneous
fat hampers the visualization of the lung parenchyma. In this contribution, an efficient tissue suppression technique is presented
which allows one to significantly enhance lung parenchyma visibility. A short inversion time inversion recovery (STIR) experiment
combined with a magnetization transfer (MT) experiment was used for magnetization preparation in order to suppress the signal
from muscle. A half-Fourier single-shot turbo spin-echo sequence was used as acquisition module. This approach was used to
perform lung anatomical imaging in eight healthy human subjects and five patients withcystic fibrosis. The results obtained demonstrate that with MT-STIR approach high quality human lung images can be obtained and that this
approach has the potential for the evaluation of lung pathologies. 相似文献
97.
Georg Jung John Hatcliff 《International Journal on Software Tools for Technology Transfer (STTT)》2007,9(5-6):417-427
Large distributed systems, including real-time embedded systems, are increasingly being built using sophisticated middleware
frameworks. Communication in such systems is often realized using in terms of asynchronous events whose propagation is implemented
by an underlying publish/subscribe service that hooks components into a generic event communication channel. Event correlation—a mechanism for monitoring and filtering events—has been introduced in some of these systems as an effective technique for
reducing network traffic and computation time. Unfortunately, even though event correlation is used heavily in frameworks
such as ACE/TAO’s real-time event-channel and in mission critical contexts such as Boeing’s Bold Stroke avionics middleware,
the industry standard CORBA Component Model (CCM) does not include a specification of event correlation. While previous proposals
for event correlation usually offer sophisticated facilities to detect combinations in the stream of incoming events, they
have not been constructed to fit within the CCM type system, and they offer relatively little support for transforming and
rearranging filtered events into meaningful output events. In this paper, we present the design rationale, syntax, and semantics
for a new and highly flexible model for event correlation that is designed for integration into the CCM type system. Our model
has been integrated and tested in the Cadena development and analysis framework, which has been designed to support development
of mission-control applications in the Boeing Bold Stroke framework.
This work was supported in part by the US Army Research Office (DAAD190110564), by DARPA/IXO’s PCES program (AFRL Contract
F33615-00-C-3044), by NSF (CCR-0306607) and by Lockheed Martin. 相似文献
98.
99.
Georg Borges Carl-Friedrich Stuckenberg Christoph Wegener 《Datenschutz und Datensicherheit - DuD》2007,31(4):275-278
Die Autoren setzen sich mit dem Gesetzentwurf zur Bek?mpfung der Computerkriminalit?t auseinander, insbesondere mit der Strafbarkeit
des Einsatzes von Analysetools. 相似文献
100.