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991.
992.
A. J. Chatten K. W. J. Barnham B. F. Buxton N. J. Ekins-Daukes M. A. Malik 《Solar Energy Materials & Solar Cells》2003,75(3-4):363-371
Luminescent collectors have advantages over geometric concentrators in that tracking is unnecessary and both direct and diffuse radiation can be collected. However, development has been limited by the performance of luminescent dyes. We have recently proposed a novel concentrator in which the dyes are replaced by quantum dots (QDs). Advantages over dyes include that the absorption threshold can be tuned by choice of dot diameter, and that the red shift between absorption and luminescence is related to the spread of dot sizes. In this paper we discuss how we have developed a self-consistent thermodynamic model for planar concentrators which allows for re-absorption by the QDs. 相似文献
993.
Slutske Wendy S.; Heath Andrew C.; Dinwiddie Stephen H.; Madden Pamela A. F.; Bucholz Kathleen K.; Dunne Michael P.; Statham Dixie J.; Martin Nicholas G. 《Canadian Metallurgical Quarterly》1997,106(2):266
The etiology of conduct disorder (CD) was examined retrospectively in a sample of 2,682 male, female, and unlike-sex adult twin pairs from the community-based Australian Twin Register. Model-fitting analyses indicated a substantial genetic influence on risk for CD, accounting for 71% of the variance (95% confidence interval [CI]?=?32–79%). There was not a statistically significant effect of the shared environment in the best-fitting model of CD, but a modest effect of the shared environment on the risk for CD could not be rejected (95% CI?=?0-32%). The magnitude of genetic and environmental influences for CD liability did not vary significantly for boys and girls, and the specific genetic and environmental mechanisms important for the development of CD appeared to be largely the same for both sexes. The fit of a multiple-threshold model raises the possibility that CD may not necessarily be a discrete entity but rather an extreme of the normal variation in conduct-disordered behavior found in the general population. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
994.
Kealy Kinda L. K.; Kuiper Nicholas A.; Klein Dana N. 《Canadian Metallurgical Quarterly》2006,38(2):158
In three studies, participants rated both real and made-up personal events on several different characteristics. These included meta-cognitive beliefs about the perceived realness and typicality of these events, imagery ratings of visual detail, and emotional ratings of intensity and feelings. Studies 1 and 2 explored the impact of event valence (pleasant versus unpleasant) on these characteristics, whereas Study 3 focused on the effects of event elaboration involving guided imagery and journaling techniques. All three studies also included consideration of individual difference factors that might either enhance or attenuate the ratings that were obtained. Both Studies 1 and 2 found that pleasant events (be they real or made-up), were viewed as more typical, and more likely to have happened and be true, than unpleasant events. This pattern of meta-cognitive judgments provided support for a general positivity hypothesis, which proposes that most individuals orient towards and emphasize pleasant rather than unpleasant life experience and events. In contrast, the imagery-related components of these events, such as visual details, location, and time, were much less sensitive to the manipulation of event valence. Strong imagery-related effects, however, were noted when events were elaborated in the final study. Furthermore, this event elaboration manipulation also resulted in heightened meta-cognitive judgments of typicality, likelihood of the event having happened, and of being true. Finally, across all three studies, a series of correlational analyses indicated that the individual difference factors did not have any systematic effect on any of the event characteristic ratings. However, when event valence was not specifically manipulated (in Study 3), depressed individuals spontaneously provided twice as many unpleasant personal events as nondepressed individuals. These findings were then discussed in terms of source-confusion issues regarding personal memory accuracy, as well as the further extension of a recent model of autobiographical memory to incorporate event properties such as valence and elaboration. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
995.
996.
Friction stir welding for the transportation industries 总被引:34,自引:0,他引:34
This paper will focus on the relatively new joining technology—friction stir welding (FSW). Like all friction welding variants, the FSW process is carried out in the solid-phase. Generically solid-phase welding is one of the oldest forms of metallurgical joining processes known to man. Friction stir welding is a continuous hot shear autogenous process involving a non-consumable rotating probe of harder material than the substrate itself. In addition, FSW produces solid-phase, low distortion, good appearance welds at relatively low cost. Essentially, a portion of a specially shaped rotating tool is plunged between the abutting faces of the joint. Once entered into the weld, relative motion between the rotating tool and the substrate generates frictional heat that creates a plasticised region around the immersed portion of the tool. The contacting surface of the shouldered region of the tool and the workpiece top contacting surface also generates frictional heat. The shouldered region provides additional friction treatment to the weld region as well as preventing plasticised material being expelled. The tool is then translated with respect to the workpiece along the joint line, with the plasticised material coalescing behind the tool to form a solid-phase joint as the tool moves forward. Although the workpiece does heat up during FSW, the temperature does not reach the melting point. Friction stir welding can be used to join most aluminium alloys, and surface oxide presents no difficulty to the process. Trials undertaken up to the present time show that a number of light weight materials suitable for the automotive, rail, marine, and aerospace transportation industries can be fabricated by FSW. 相似文献
997.
Phillips Susan D.; Pazienza Nicholas J.; Ferrin Howard H. 《Canadian Metallurgical Quarterly》1984,31(4):497
Administered measures of decision-making styles and problem-solving appraisal to 243 undergraduates and a canonical analysis was employed to examine the relationships between the 2 sets of variables. Three significant canonical roots suggest that (a) individuals who employ rational decision-making strategies are likely to approach (rather than avoid) problematic situations, (b) individuals who endorse dependent decisional strategies are likely to report that they approach problematic situations but do so without particular confidence in their problem-solving abilities, and (c) the endorsement of both rational and intuitive strategies for decision making is likely to be accompanied by appraisals of both greater confidence and diminished personal control. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
998.
999.
We contrast in this article the system demands imposed by brute force, complete replanning, and a new, goal-directed approach called dynamic plan revision (DPR). One of the two processes must be invoked when some aspects of the environment change and currently existing plans are likely to fail. Complete replanning is conceptually simpler but requires significantly more computation because it reproduces also those plan steps that have not been affected by the changes. DPR attempts to minimize the scope of replanning and makes to the current plans as small amount of modification as possible. the more rapidly the environment changes, the less practical complete replanning becomes. the issue is even more significant with time-critical applications DPR uses goal hierarchies produced at the same time when plans are generated. the planning systems has an “active attitude” toward the feedback from the environment and takes advantage of all information becoming available during plan execution. We have also developed and implemented a distributed version of this approach in the domain of Distributed Manufacturing Operations [N. V. Findler and J. Gao, Data and Know. Eng., 2, 285–301 (1987); Q. Ge and N. V. Findler, Proc. Austr. Joint Conf. on Art. Int., 439–455 (1988); N. Y. Findler and G. Ge, Int. J. Intell. Syst., 4 , 459–470 (1989)]. the relevant algorithms are given in the Appendices A and B. © 1994 John Wiley & Sons, Inc. 相似文献
1000.
This paper describes a new robust method to decompose a free-form surface into regions with specific range of curvature and provide important tools for surface analysis, tool-path generation, and tool-size selection for numerically controlled machining, tessellation of trimmed patches for surface interrogation and finite-element meshing, and fairing of free-form surfaces. The key element in these techniques is the computation ofall real roots within a finite box of systems of nonlinear equations involving polynomials and square roots of polynomials. The free-form surfaces are bivariate polynomial functions, but the analytical expressions of their principal curvatures involve polynomials and square roots of polynomials. Key components are the reduction of the problems into solutions of systems of polynomial equations of higher dimensionality through the introduction ofauxiliary variables and the use ofrounded interval arithmetic in the context of Bernstein subdivision to enhance the robustness of floating-point implementation. Examples are given that illustrate our techniques. 相似文献