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991.
Fouling or scaling, i.e., the occurrence of deposits on tubes, heat exchangers, and other devices, is a common problem in industrial and domestic processes. Many anti‐fouling techniques exist, both chemically and non‐chemically. The efficiency of non‐chemical methods is still controversial, although the use of these devices is already widespread in industry. In this contribution, a case study is presented in which the operation of such a device is demonstrated. The electronic water treatment device under study was connected to a 2 m‐long copper tube immersed in a water bath with a temperature of 65 °C. A short‐term experiment revealed that the device did not alter the water chemistry and that locally, fouling was prevented by the device. However, the potential for fouling further downstream was not reduced. A long‐term experiment further confirmed the findings of the short‐term experiment showing that locally, the device has an anti‐fouling action as a significant increase in weight was observed when the device was switched off and a significant decrease in weight was observed when the device was switched on. 相似文献
992.
Jakobus U. Bingle M. Schoeman M. Van Tonder J.J. Illenseer F. 《Microwave Magazine, IEEE》2008,9(6):76-85
In this article we have presented some of the more recent modeling options available in FEKO (waveguide ports, combination with FEM, dielectric GO, PBCs, coupling with networks) that are specifically useful to the microwave engineer. In addition to presenting some of the theory, we focused on examples to show the application of each method and discussed their advantages. The examples were kept intentionally simple such that the relevant advantages can easily be highlighted. 相似文献
993.
F Nayeri R Cameron E Chryssanthou L Johansson C S?derstr?m 《Canadian Metallurgical Quarterly》1997,29(6):635-638
A 48-year-old woman with no cardiovascular risk factors was admitted to the hospital because of acute dyspnea. At 27-year-old, she developed Hodgkin's disease, that was successfully treated with splenectomy, combined chemotherapy (nitrogen mustard, vincristine, procarbazine, prednisone-MOPP regimen) and radiotherapy (4500 rads). At 43-year-old the lymphoma relapsed and she had further chemotherapy with doxorubicin, bleomycin, vinblastina and dacarbazine. After this treatment, she had an episode of pulmonary edema, attributed to doxorubicin acute cardiotoxicity. She responded to digitalis and diuretics and was discharged with an electrocardiogram (ECG) showing left bundle branch block and a normal echocardiogram. The patient enjoyed good health for several years and 4 months before the present admission the ECG and echocardiogram were unchanged. On this admission there were signs of left ventricular failure with acute pulmonary edema, and a new soft apical murmur (3-4 Levine). The patient required endotracheal intubation and high doses of diuretics, digitalis and vasodilators. The cardiac enzymes were negative, the serial ECGs confirmed left bundle branch block, while the echocardiogram showed moderate to severe mitral regurgitation, akinesia of the interventricular septum and inferior wall with dilation of the left ventricle. A previous silent myocardial infarction was suspected. After recovery, she underwent cardiac catheterization confirming akinesia of the interventricular septum and inferior wall with moderate mitral regurgitation, while coronary angiography showed a critical ostial stenosis of the right coronary artery. In view of a dipyridamole-thallium scan negative for myocardial viability, reperfusion was not attempted. With changes in radiotherapeutic techniques, the incidence of radiation-induced heart disease (pericarditis, myocarditis, conduction abnormalities and, rarely, occlusive coronary artery disease) is declining. Nevertheless, after irradiation of the chest and mediastinum a longterm cardiological follow-up is useful in selecting patients at higher risk of radiation-induced coronary artery disease, who will eventually require coronary angiography and reperfusion intervention. 相似文献
994.
995.
996.
This article reports empirical findings from four inter-related studies, with an emphasis on collocated sharing. Collocated sharing remains important, using both traditional and emerging image-related technologies. Co-present viewing is a dynamic, improvisational construction of a contingent, situated interaction between story-teller and audience. The concept of performance, as articulated differently by Erving Goffman and Judith Butler, is useful understand the enduring importance of co-present sharing of photos and the importance of oral narratives around images in enacting identity and relationships. Finally, we suggest some implications for both HCI research and the design of image-related technologies. 相似文献
997.
Summary The uniqueness and mathematical stability of the Dirichlet boundary value problem of linear elastostatics is studied. The
problem is posed as a set of partial differential equations in terms of displacements and Dirichlet-type of boundary conditions
(displacements) for arbitrary bounded domains. Then for the circular interior domain the closed form analytical solution is
obtained, using an extended version of the method of separation of variables. This method with corresponding complete solution
allows for the derivation of a necessary and sufficient condition for uniqueness. The results are compared with existing energy
and uniqueness criteria. A parametric study of the elastic characteristics is performed to investigate the behaviour of the
displacement field and the strain energy distribution, and to examine the mathematical stability of the solution. It is found
that the solution for the circular element with hourglass-like boundary conditions will be unique for all v ≠ 0.5, 0.75, 1.0 and will be mathematically stable for all v ≠ 0.75. Locking of the circular element occurs for v = 0.75 as the energy tends to infinity. 相似文献
998.
Tomography with high angular annular dark field scanning transmission electron microscopy at atomic resolution can be greatly improved if one is able to take advantage of prior knowledge. In this paper we present a reconstruction technique that explicitly takes into account the microscope parameters and the atomic nature of the projected object. This results in a more accurate estimate of the atomic positions and in a good resistance to noise. The reconstruction is a maximum likelihood estimator of the object. Moreover, the limits to the precision have been explored, allowing for a prediction of the amount of expected noise in the reconstruction for a certain experimental setup. We believe that the proposed reconstruction technique can be generalized to other tomographic experiments. 相似文献
999.
1000.
We consider the problem of optimal worksharing between two adjacent workers each of whom processes a fixed task in addition to their shared task(s). We use a Markov Decision Process (MDP) model to compute optimal policies and provide a benchmark for evaluating threshold policy heuristics. Our approach differs from previous studies of dynamic line balancing in that we focus on system architecture factors that affect the performance improvement opportunity possible through worksharing relative to a traditional static worker allocations, as well as practical heuristics for worksharing. We find that three such factors are significant whether we use an optimal or a heuristic control policy: ability to preempt the shared task, granularity of the shared task and overall variability of the task times. Understanding the role of these factors in a given production environment provides a means for determining where and how worksharing can have significant logistical benefits. 相似文献