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21.
Ambiguous requirements and those that emerge late in the design cycle often complicate development and throw off established schedules. The authors describe how reformulating information missing at the design stage into a flexibility requirement can turn the absent data into a design driver. Designers constantly run into issues that have yet to be understood through specification, system design, or standardization. Changes in evolving technologies and businesses often result in unstable system requirements. Reliable hardware or mechanical details might not be available until very late in the development process. Yet engineers must initiate software development even though some subsystem details have not yet been completely defined. Missing information and related flexibility requirements can lead to a design plagued by many well-known problems that affect performance, modularity, scalability, and clear separation of concerns. In some cases, developers must sacrifice rules of thumb to maintain planned development schedules. Providing flexibility for everything in the system isn't possible, so developers will always need to determine the static requirements and explicitly state where continued development and rapid modification require flexibility 相似文献
22.
A metrological complex for reproduction and transmission of the length units in the range of 0.001 to 50 m (MKD-50) with a
total error of 0.2+0.25L μm, where L is the measured length in meters, is described. The MKD-50 complex has been entered into
the State Register of Measurement Standards of Ukraine as a working standard for length units of 1–50 m (VETU 01-03-05-98).
Ukraine. Translated from Izmeritel’naya Tekhnika, No. 12, pp. 31–33, December, 1999. 相似文献
23.
We describe how the cash-point service problem of Formal Methods ’99 is specified using DisCo [Dis, JKS91].
Received January 2000 / Accepted in revised form December 2000 相似文献
24.
A passive chilled beam is a source of natural convection, creating a flow of cold air directly into the occupied zone. Experiments were conducted in a mock-up of an office room to study the air velocities in the occupied spaces. In addition, velocity profiles are registered when underneath heat loads exist and the cool and warm air flows interact. Experimental laboratory study revealed that in the case of the underneath heat gains, even no upward plume was generated and the dummy only acted as a flow obstacle, having a significant effect on the velocity profile. Furthermore, in an actual occupied office environment, the thermal plumes and the supply air diffuser mixed effectively the whole air volume. The maximum air velocity measured was still below 0.25 m/s with the extremely high heat gain of 164 W/m2. The results demonstrate that analysis methods were the interaction of convection flow and jet are not taken into account could not accurately describe air movement and draught risk in the occupied room space. 相似文献
25.
We report on a model to determine the light transmission of solid particles in immersion liquids. Using the model, optical and physical properties of suspensions such as the refractive index of the particles can be retrieved. The model can also be used in the case of colored suspensions, where the detection of only the maximum transmission would give an inaccurate refractive index for a particle. The validity of the method was tested with CaF(2) particles. Potential applications include scientific studies of the optical properties of micro- and nanoparticles or microorganisms in a liquid matrix. The model is also useful in industry where monitoring of suspensions and colloids is an issue. 相似文献
26.
At present, ceiling-mounted diffusers are very popular for indoor air distribution, particularly in offices, owing to greater efficiency in the distribution of the air supply and a more comfortable indoor environment. The objective of this study is to construct an effective model to design the indoor airflow of an attached plane jet after its impingement with the corner in a room. In this study, a full-scale test facility was set up to obtain detailed experimental data. One commercial CFD tool, CFX 11.0, was used to simulate the air velocity distribution of an attached plane air jet bounded by the ceiling and an insulated wall. One semi-empirical model was also constructed to predict the impingement jet velocity. The results show that bout the semi-empirical model and CFX 11.0 were able to predict the maximum velocity of an impinging jet at low Reynolds numbers, 1000 and 2000, with an inaccuracy of ±11%. However, the semi-empirical model could be more conveniently used to predict the maximum jet velocity decay after its impingement the corner in a room than CFD simulation in terms of accuracy and the time required to design the indoor airflow pattern. 相似文献
27.
Iiro Hietanen Jukka Lindgren Risto Orava Tuure Tuuva Martti Voutilainen
Richard Brenner
Mikael Andersson
Kari Leinonen Hannu Ronkainen 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1991,310(3):671-676Double-sided silicon strip detectors with integrated coupling capacitors and polysilicon resistors have been processed on a 100 mm wafer. A detector with an active area of 19 × 19 mm2 was connected to LSI readout electronics and tested. The strip pitch of the detector is 25 μm on the p-side and 50 μm on the n-side. The readout pitch is 50 μm on both sides. The number of readout strips is 774 and the total number of strips is 1161. On the p-side a signal-to-noise of 35 has been measured using a 90Sr β-source. The n-side has been studied using a laser. 相似文献
28.
29.
Tapio Salon Risto K. Peltonen und Brita Ståhlström 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1958,107(5):401-406
Zusammenfassung Es wird eine potentiometrische Methode für die Bestimmung des Gesamtsäuregehaltes der Weine und Liköre beschrieben und auf Grund experimenteller Versuche der Einfluß verschiedener Faktoren auf die Resultate diskutiért. 相似文献
30.