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Cast titanium as implant material 总被引:5,自引:0,他引:5
S. Mohammadi L. Wictorin L. E. Ericson P. Thomsen 《Journal of materials science. Materials in medicine》1995,6(8):435-444
The tissue response in rats to implants made of machined and cast titanium was evaluated after 1 and 12 weeks. The implants consisted of a circular plate portion, located in the abdominal wall, and a cylindrical rod portion protruding into the peritoneal cavity. The chemical and topographical surface properties of the two types of implants differed considerably. The implants with surrounding tissue were processed en bloc for light and electron microscopy. The bulk metal was removed by an electrochemical procedure which permitted the sectioning and evaluation of the intact implant-tissue interface. The general distribution of macrophages and fibroblasts was the same around the plate portion of both types of implants. Macrophages constituted the predominating cell type with the highest concentration in the innermost cell zone closest to the implant. The number of macrophages per section area was significantly higher around machined implants. Multinuclear giant cells, always located at the implant surface, were more frequent around cast implants. The majority of the intraperitoneal rod portions were partially (1 week) or completely (12 weeks) covered by tissue; partial or complete overgrowth of tissue was rare for machined rod portions. Imaging electron energy loss spectroscopy demonstrated the presence of titanium in macrophages in the peripheral part of the tissue capsule around cast, but not machined implants. We conclude that the tissue responses to the two types of titanium implants differed considerably in the two biological environments (soft tissue in abdominal wall; peritoneal cavity) examined and that the response in one environment does not predict the response in the other. We also believe that improvements have to be made in the casting procedure in order to reduce surface roughness and contamination before cast implants can be used in clinical applications. 相似文献
6.
Jamshid Mohammadi 《Structural Safety》1985,2(4):301-308
Lifeline systems are vulnerable to two types of hazards arising from potential earthquake sources. These are the hazard of a fault-rupture strike on elements of a lifeline system and the hazard of overstress induced in different elements of the system because of the ground vibration. An optimum design method is presented in this paper for the design of a lifeline system for a maximum accepted probability of failure because of any of the two modes of failure. The method may be used to determine an optimum path between a number of fixed points which represent supply or demand stations in the system. 相似文献
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Hajipour Abdol R. Khorsandi Zahra Ahmadi Mehnoosh Jouypazadeh Hamidreza Mohammadi Bahareh Farrokhpour Hossein 《Catalysis Letters》2021,151(10):2842-2850
Catalysis Letters - Several highly efficient and magnetically recyclable cobalt catalytic systems were prepared using magnetic chitosan and some safe and available organic compounds... 相似文献
8.
Mohammadi Hossein Mohammadi Mohammad Amiri Iraj Sadegh Hosseinghadiry Mahdiar 《SILICON》2021,13(3):747-755
Silicon - In this paper, a new structure: triple work function metal gate SOI MESFET, intended for integration into the deep-submicron CMOS technology, is proposed. The gate of the device consists... 相似文献
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Dalibor Petković Shahaboddin Shamshirband Hadi Saboohi Tan Fong Ang Nor Badrul Anuar Nenad D. Pavlović 《Applied Intelligence》2014,41(3):887-896
The prerequisite for new versatile grippers is the capability to locate and perceive protests in their surroundings. It is realized that automated controllers are profoundly nonlinear frameworks, and a faultless numerical model is hard to get, in this way making it troublesome to control utilizing tried and true procedure. Here, a design of an adaptive compliant gripper is presented. This design of the gripper has embedded sensors as part of its structure. The use of embedded sensors in a robot gripper gives the control system the ability to control input displacement of the gripper and to recognize specific shapes of the grasping objects. Since the conventional control strategy is a very challenging task, soft computing based controllers are considered as potential candidates for such an application. In this study, the polynomial and radial basis function (RBF) are applied as the kernel function of Support Vector Regression (SVR) to estimate and predict optimal inputs displacement of the gripper according to experimental tests and shapes of grasping objects. Instead of minimizing the observed training error, SVR poly and SVR rbf attempt to minimize the generalization error bound so as to achieve generalized performance. The experimental results show that an improvement in predictive accuracy and capability of generalization can be achieved by the SVR approach compared to other soft computing methodology. 相似文献
10.
Hadi Shahriar Shahhoseini Ehsan Saleh Kandzi Morteza Mollajafari 《The Journal of supercomputing》2014,67(1):31-46
Parallel machines are extensively used to increase computational speed in solving different scientific problems. Various topologies with different properties have been proposed so far and each one is suitable for specific applications. Pyramid interconnection networks have potentially powerful architecture for many applications such as image processing, visualization, and data mining. The major advantage of pyramids which is important for image processing systems is hierarchical abstracting and transferring the data toward the apex node, just like the human being vision system, which reach to an object from an image. There are rapidly growing applications in which the multidimensional datasets should be processed simultaneously. For such a system, we need a symmetric and expandable interconnection network to process data from different directions and forward them toward the apex. In this paper, a new type of pyramid interconnection network called Non-Flat Surface Level (NFSL) pyramid is proposed. NFSL pyramid interconnection networks constructed by L-level A-lateral-base pyramids that are named basic-pyramids. So, the apex node is surrounded by the level-one surfaces of NFSL that are the first nearest level of nodes to apex in the basic pyramids. Two topologies which are called NFSL-T and NFSL-Q originated from Trilateral-base and Quadrilateral-base basic-pyramids are studied to exemplify the proposed structure. To evaluate the proposed architecture, the most important properties of the networks are determined and compared with those of the standard pyramid networks and its variants. 相似文献