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131.
132.
The purpose of this paper is to introduce some techniques of biomechanical simulation through an example — simulation of manual lifting. The motivation for developing biomechanical simulation is discussed. Biomechanical simulation is defined and compared with the traditional biomechanical modeling. The formulation of biomechanical simulation of manual lifting is presented, and some practical techniques used to conduct a simulation of manual lifting are provided. 相似文献
133.
P Ghadirian A Jeanneret C Perret J Latreille J Ayoub D Sanderson 《Canadian Metallurgical Quarterly》1997,18(3):259-264
SETTING: Patients were recruited from Siriraj, Bamrasnaradura, and Central Chest Hospitals, the three major hospitals responsible for tuberculosis patients in Bangkok, Thailand, and vicinity. OBJECTIVE: To evaluate a new rapid serologic test, the MycoDot test, for diagnosis of tuberculosis (TB). DESIGN: The study was conducted as a cross-sectional survey. A total of 594 patients were tested with the MycoDot test. This included 142 human immunodeficiency virus (HIV) seropositive patients with active TB, 144 HIV seronegative patients with active TB, 153 HIV seropositive controls, and 155 HIV seronegative controls. RESULTS: The sensitivity of the MycoDot test for detection of TB was 40.1% in HIV seropositive patients, compared with 63.2% in HIV seronegative patients (P < 0.001). If only patients with laboratory proven TB were evaluated, the sensitivity was 40.6% in seropositive and in 70.8% seronegative patients. The sensitivity of the MycoDot test was similar in TB patients with pulmonary and extra-pulmonary disease. The sensitivity of the test in patients with CD4 counts > or = 200 cells/mm3 was significantly higher than in those with CD4 counts < 200 cells/mm3. The specificity of the test was 97.4%, and was identical in HIV seropositive and seronegative individuals. CONCLUSION: The MycoDot test had a higher sensitivity for the diagnosis of TB among HIV seronegative than HIV seropositive patients. Although the MycoDot test has a less than optimal sensitivity, the test specificity approaches 100%. It may be useful in patients with suspected TB and negative smears and in extra-pulmonary TB. 相似文献
134.
This paper studies the design and performance of cooled ceiling and displacement ventilation (CC/DV) systems application for buildings in Beirut for the purpose of saving energy. The transient thermal response of spaces cooled by the combined CC/DV system is needed for performance assessment. For that reason, the plume‐multi‐layer model of CC/DV cooled spaces is extended to transient applications. A design procedure for the combined CC/DV system in Beirut humid climate and buildings is developed to insure that both indoor air quality and comfort are satisfied within the conditioned zone. The contribution of the proposed procedure is that it guarantees that the stratification height (occupied zone) is at 1.1 m taking into consideration the plumes from internal sources and non‐isothermal walls. The design procedure is applied to a case study in Beirut to design a system for a typical office space at 85 W m?2 sensible cooling load. The CC/DV system size is compared with the size of a conventional mixed convection system. It is found that the size of the CC/DV system is 10.2 kW compared to conventional system size of 7.9 and 13.4 kW at the 30 and 100% fresh air supply, respectively. For the same indoor air quality and thermal comfort level, the CC/DV system consumed 21% less cooling energy than the conventional 100% fresh air system over the cooling season. The initial cost of the CC/DV system is higher, but the pay back period based on transient operation is less than 5 yr. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
135.
Computerized human motion simulation allows generation of dynamic human motions on computers. Biomechanical stresses can be estimated using the motions generated on a computer without actually collecting joint coordinate data. A two-dimensional whole-body lifting simulation model is presented in this paper. The model assumes that humans perform lifting activities based on minimization of physical work, subject to various constraints. The simulation method contains three major computation units: trajectory formation unit, dynamics of motion unit, and nonlinear optimization unit. The trajectory formation unit generates smooth polynomials representing motion characteristics of human lifting. Kinematics and kinetics are calculated in the dynamics unit. Objective and constraint functions are evaluated in the optimization unit. Optimal motions are generated by minimizing the objective function, subject to the constraints. Computation methods of the three units and simulation results are presented. 相似文献
136.
137.
采用非线性程序,模拟火灾中钢筋混凝土结构中混凝土与钢筋之间的粘结机理。通过1个梁的拉拔力试验、1个特定温度下的梁试验和在两种标准火灾中的4个足尺梁试验,证明数值模型的准确可靠性。该模型对火灾中钢筋混凝土构件和结构响应的预测满足精度要求,粘结连接单元也能满足火灾中钢筋混凝土结构3维分析的计算精度和计算效率的要求。结果表明:混凝土与钢筋之间的粘结条件对钢筋混凝土结构的耐火性能有重要影响,尤其当钢筋的温度较高(大于500°C)时。目前使用的火灾中钢筋混凝土结构粘结条件的假设是偏不安全的。 相似文献
138.
The polycarbonate (PC)/polystyrene (PS) blend is an immiscible system. The use of copolymers as compatibilizers in blends is one approach that is being developed within the larger field of polymer alloys. In this study, PC was ozonized to create peroxides and hydroperoxides on the polymer chain. These functional groups under heating conditions were used to initiate the radical polymerization of styrene (vinyl monomers) to give graft copolymers. The first part of this study was dedicated to the examination of the kinetics of the styrene polymerization initiated by an ozonized PC. However, the structure of the graft copolymers was confirmed by IR spectroscopy, and the molecular weight of the PS graft chain was determined by gel permeation chromatography. The compatibilized bends were prepared by melt blending in an internal mixer. The morphologies of the PC/PS/graft copolymer blend were examined by transmission electron microscopy and were finer than those of an uncompatibilized blend. The tensile properties of these blends were also investigated. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
139.
The use of Fiber-Reinforced Polymer (FRP) materials dates back to the early 1940s when they were used in aerospace and naval applications. During the 1970s and early 1980s, FRP started being used in civil engineering applications for new construction, but more importantly for repair and strengthening of existing structures. However, experimental research showed that the typical failure mode of reinforced concrete (RC) structures strengthened with FRP composite materials is due to the debonding that occurs at the interface between concrete and FRP. The bond between FRP and concrete is therefore the key factor controlling the behavior of these structures since it limits the full use of the FRP strength. The paper evaluates the effect of the debonding failure on the response of FRP-strengthened RC beams. A nonlinear RC beam element with bond-slip between the concrete and the FRP laminates is developed and used to analyze several test specimens and to investigate their corresponding failure mode. The model was also used to study the reduction factor of FRP tensile strength of simply supported strengthened RC girders due to debonding failure. This reduction factor proved to be affected by several parameters: (a) the bond strength between FRP and concrete interface; (b) the concrete strength; (c) the thickness of FRP; (d) the modulus of FRP; (e) the width of FRP laminate; and (f) the development length of the FRP sheet. A large number of beam specimens were analyzed in order to conduct a thorough evaluation of debonding failure of RC beams strengthened with FRP laminates. Based on these studies, new equations that account for the aforementioned parameters were proposed to address the reduction in FRP strength due to debonding failure. 相似文献
140.
Mejed Chemli Ayoub Haj Saïd Nejmeddine Jaballah Jean-Louis Fave Mustapha Majdoub 《Synthetic Metals》2011,161(15-16):1463-1468
A new electroluminescent poly(p-phenylene) (PPP)-type polymer (CHALC-PPP) incorporating chalcone-type groups as side-chains has been synthesized via a chemical modification of a precursor acyl-functionalized polymer. The chemical structure of the polymer was characterized by 1H NMR, 13C NMR, and FT-IR spectroscopic analysis. CHALC-PPP contains a substitution ratio of 40% of vinylaryl groups. It is fully soluble in common organic solvents and has a number–average molecular weight of 3750 g/mol. CHALC-PPP thin solid film absorbs in UV and emits in the green region with a maximum at 512 nm. From the cyclic voltammetry analysis, the HOMO and LUMO energies levels values are ?5.67 and ?2.70 eV, respectively. A multilayer diode device with the configuration ITO/PEDOT:PSS/CHALC-PPP/BCP/Al emitting a green light has been fabricated. 相似文献