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排序方式: 共有2164条查询结果,搜索用时 312 毫秒
81.
Xiangyu Meng Fusheng YangZewei Bao Jianqiang DengNyallang N. Serge Zaoxiao Zhang 《Applied Energy》2010
In order to utilize the low grade heat energy efficiently, the preliminary scheme of a metal hydride based Combined Cooling, Heating and Power (CCHP) system driven by solar energy and industrial waste heat was proposed, in which both refrigeration and power generation are achieved. Following a step-by-step procedure recently developed by the authors, two pairs of metal hydrides were selected for the CCHP system. The working principle of the system was discussed in detail and further design of the configuration for CCHP was conducted. Based on the cycle mentioned above, the models of energy conversion and exergy analysis were set up. The multi-element valued method was used to assess the performance of the CCHP system in a whole sense, thus the analysis of influence factors on the system performance can be carried out. The typical climate conditions of Xi’an in 2005 were taken for discussion, and the results showed that the system performance is mainly affected by the quantity of solar radiation energy. The objective of the system’s optimization is to increase the exergy efficiency of the metal hydride heat pump, based on the quantity of solar radiation energy. The comparison with two different traditional types of CCHP systems proved that the novel CCHP system is superior to the traditional CCHP systems concerning the integrated performance. 相似文献
82.
V. I. Sergeev 《Journal of Machinery Manufacture and Reliability》2013,42(3):196-204
The formulation and methodology are considered for solving one class of problems in the field of accuracy research for an electromechanical chain of devices with parameters of nonlinear elements, changing the process of problem solving in the framework of one common formulation. Special attention is drawn to the approach to determining the stability of motion. An example is given in a sufficiently general statement of the problem with a deterministic and stochastic approach to its solution. 相似文献
83.
The Hybrid Finite Element Mixing Cell Method: A New Flexible Method for Modelling Mine Ground Water Problems 总被引:1,自引:0,他引:1
Serge Brouyère Ph. Orban S. Wildemeersch J. Couturier N. Gardin A. Dassargues 《Mine Water and the Environment》2009,28(2):102-114
Dewatering operations often stop at mine closure. The ground water rebound can have undesirable consequences, which numerical
models can help one understand and manage. However, classical modelling techniques are relatively unsuitable to these contexts.
While spatially distributed and physically based models suffer difficulties due to the lack of data and the complexity of
geological and hydrogeological conditions, black-box models are too simple to deal with the problems effectively. A new modelling
method is proposed to simulate ground water environments in which water flows through mined (exploited) and unmined (unexploited)
areas. Exploited zones are simulated using a group of mixing cells possibly interconnected by pipes. Unexploited zones are
simultaneously simulated using classical finite elements. This combined approach allows explicit calculation of ground water
flows around the mine and mean water levels in the exploited zones. Water exchanges between exploited zones and unexploited
zones are simulated in the model using specifically defined internal boundary conditions. The method is tested on synthetic
cases of increasing complexity, and first results from a real case study are presented. 相似文献
84.
85.
Sawsan Abdul-Majid Imad Hasan Qi Zheng Ramón Maldonado-Basilio Serge Bidnyk Trevor Hall 《电信纪事》2013,68(1-2):49-55
Radio-over- fibre (RoF) technology is receiving large attention due to its ability to provide simple antenna front ends, increased capacity and increased wireless access coverage. Coherently detected RoF systems would enable the information to be carried in both the amplitude and phase or in different states of the polarisation of the optical field. Additionally, the selectivity of coherent receiver is very well suited for access networks. We present a 90° optical hybrid built on a silicon-on-insulator planar light-wave circuit, which can be used as the optical front end of the digital coherent receiver in a digitised RoF link and will lead to reduced receiver footprint and cost. The optical hybrid circuit includes 2?×?2 and 4?×?4 multimode interference (MMI) splitters, in a polarisation diversity configuration. The simulation results at vacuum wavelength 1,550 nm show polarisation independence and phase errors between the ports of less than 0.03°. The properties of the prototyped 4?×?4 MMI were measured over a wide range of wavelengths. The 2?×?2 and 4?×?4 MMI showed nearly equal splitting ratios. Measurements of the relative phase relationship between the ports for Transverse Electric mode polarisation are shown to match the simulation results. 相似文献
86.
Kimberly Sablon Andrei Sergeev Nizami Vagidov Andrei Antipov John Little Vladimir Mitin 《Nanoscale research letters》2011,6(1):584
We analyze the effect of doping on photoelectron kinetics in quantum dot [QD] structures and find two strong effects of the built-in-dot charge. First, the built-in-dot charge enhances the infrared [IR] transitions in QD structures. This effect significantly increases electron coupling to IR radiation and improves harvesting of the IR power in QD solar cells. Second, the built-in charge creates potential barriers around dots, and these barriers strongly suppress capture processes for photocarriers of the same sign as the built-in-dot charge. The second effect exponentially increases the photoelectron lifetime in unipolar devices, such as IR photodetectors. In bipolar devices, such as solar cells, the solar radiation creates the built-in-dot charge that equates the electron and hole capture rates. By providing additional charge to QDs, the appropriate doping can significantly suppress the capture and recombination processes via QDs. These improvements of IR absorption and photocarrier kinetics radically increase the responsivity of IR photodetectors and photovoltaic efficiency of QD solar cells. 相似文献
87.
88.
Pichia sorbitophila grows rapidly in the presence of very high NaCl concentrations. Under these conditions, even when the K(+) concentration is low, P. sorbitophila cells can maintain low Na(+) and high K(+) contents. This remarkable capacity of P. sorbitophila fails when the external pH is not acidic. This indicates that Na(+) efflux is mediated by an electroneutral Na(+)/H(+) antiporter. We have cloned and sequenced two genes designated as PsNHA1 and PsNHA2, which probably encode two antiporters of this type. The genes present high similarity with the corresponding genes from other yeasts. The heterologous expression of PsNHA1 or PsNHA2 in a Saccharomyces cerevisiae mutant lacking the Na(+) efflux systems and sensitive to high concentrations of Na(+) and K(+) rescued the tolerance and the ability to extrude both cations. The Accession Nos of the sequenced DNA fragments are: PsNHA1, AJ496431; PsNHA2, AJ496432. (TC 2.A.36) Copyright 2002 John Wiley & Sons, Ltd. 相似文献
89.
N. E. Arancibia R. V. Bogdanov R. A. Kuznetsov A. S. Sergeev V. B. Glushkova T. I. Panova 《Radiochemistry》2002,44(5):508-517
Immobilization of radioactive wastes (RW) containing large amounts of process alkalis in ceramic matrices based on acid and basic rocks is studied. Immobilizing characteristics of samples with an RW content of 15% are obtained. The best geoceramic matrices are characterized by the forward leaching rates with double-distilled water of 1 × 10-
4 and 1 × 10-
5 g cm-
2 day-
1 for Sr and Cs, respectively, and the steady-state leaching rate of about 2 × 10-
6 g cm-
2 day-
1. Possible fixation mechanisms of the radionuclides in the matrices studied are discussed. Comparative analysis of properties of the geoceramic matrices and borosilicate and some other existing matrices for RW immobilization makes it possible to recommend some kinds of the geoceramics as matrices for immobilization of nonfractionated intermediate- and high-level radioactive wastes. 相似文献
90.
Equations that describe the photobleaching of photochromic layers illuminated by Gaussian laser beams are given. The photochromic samples are made of thionine, triethanolamine, and polyvinyl alcohol and follow simple kinetics law. Spatial absorbance and time-dependent power transmittance are well described by the developed equations. The model is used to calculate the Gaussian dimension of helium-neon laser beams from kinetics data. 相似文献