全文获取类型
收费全文 | 1961篇 |
免费 | 86篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 21篇 |
综合类 | 3篇 |
化学工业 | 536篇 |
金属工艺 | 66篇 |
机械仪表 | 43篇 |
建筑科学 | 90篇 |
矿业工程 | 12篇 |
能源动力 | 50篇 |
轻工业 | 127篇 |
水利工程 | 9篇 |
石油天然气 | 6篇 |
无线电 | 144篇 |
一般工业技术 | 398篇 |
冶金工业 | 239篇 |
原子能技术 | 10篇 |
自动化技术 | 297篇 |
出版年
2024年 | 6篇 |
2023年 | 22篇 |
2022年 | 88篇 |
2021年 | 83篇 |
2020年 | 46篇 |
2019年 | 49篇 |
2018年 | 48篇 |
2017年 | 63篇 |
2016年 | 72篇 |
2015年 | 51篇 |
2014年 | 75篇 |
2013年 | 122篇 |
2012年 | 113篇 |
2011年 | 111篇 |
2010年 | 109篇 |
2009年 | 81篇 |
2008年 | 100篇 |
2007年 | 91篇 |
2006年 | 66篇 |
2005年 | 61篇 |
2004年 | 48篇 |
2003年 | 39篇 |
2002年 | 42篇 |
2001年 | 27篇 |
2000年 | 37篇 |
1999年 | 15篇 |
1998年 | 54篇 |
1997年 | 27篇 |
1996年 | 36篇 |
1995年 | 26篇 |
1994年 | 19篇 |
1993年 | 18篇 |
1992年 | 10篇 |
1990年 | 9篇 |
1989年 | 11篇 |
1988年 | 9篇 |
1987年 | 10篇 |
1986年 | 11篇 |
1985年 | 10篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1982年 | 7篇 |
1981年 | 11篇 |
1980年 | 16篇 |
1977年 | 10篇 |
1976年 | 9篇 |
1975年 | 7篇 |
1974年 | 9篇 |
1973年 | 6篇 |
1971年 | 6篇 |
排序方式: 共有2051条查询结果,搜索用时 15 毫秒
1.
2.
Victor Chabanenko Roman Puźniak Adam Nabiałek Sergei Vasiliev Vladimir Rusakov Loh Huanqian Ritta Szymczak Henryk Szymczak Jan Jun Janusz Karpiński Vitaly Finkel 《Journal of Low Temperature Physics》2003,130(3-4):175-191
We present a study of magneto-thermal instabilities in polycrystalline MgB2 superconductor, by magnetic hysteresis loop measurements and by investigations of magnetic flux dynamics with a miniature Hall probe. Temperature and magnetic field ranges where the flux jumps may be observed have been determined. On the basis of measurements of the magnetic flux dynamics, an average magnetic diffusivity describing the process of the flux jump is estimated. This parameter is compared with the thermal and magnetic diffusivities calculated on the basis of available data for thermal conductivity, heat capacity and resistivity. It is shown that the estimated value of the field of the first flux jump is influenced significantly by the field dependence of specific heat. In order to explain the observed phenomenon, the temperature reached by the sample during the flux jump at different magnetic fields is calculated. 相似文献
3.
Hayden J.D. Taft R.C. Kenkare P. Mazure C. Gunderson C. Nguyen B.-Y. Woo M. Lage C. Roman B.J. Radhakrishna S. Subrahmanyan R. Sitaram A.R. Pelley P. Lin J.-H. Kemp K. Kirsch H. 《Electron Devices, IEEE Transactions on》1994,41(12):2318-2325
An advanced, high-performance, quadruple well, quadruple polysilicon BiCMOS technology has been developed for fast 16 Mb SRAM's. A split word-line bitcell architecture, using four levels of polysilicon and two self-aligned contacts, achieves a cell area of 8.61 μm2 with conventional I-line lithography and 7.32 μm2 with I-line plus phase-shift or with deep UV lithography. The process features PELOX isolation to provide a 1.0 μm active pitch, MOSFET transistors designed for a 0.80 μm gate poly pitch, a double polysilicon bipolar transistor with aggressively scaled parasitics, and a thin-film polysilicon transistor to enhance bitcell stability. A quadruple-well structure improves soft error rate (SER) and allows simultaneous optimization of MOSFET and bipolar performance 相似文献
4.
5.
In this paper we have tried to build effective model for classification of motor oils by base stock and viscosity class. Three (3) sets of near infrared (NIR) spectra (1125, 1010, and 1050 spectra) were used for classification of motor oils into 3 or 4 classes according to their base stock (synthetic, semi-synthetic, and mineral), kinematic viscosity at low temperature (SAE 0W, 5W, 10W, and 15W) and kinematic viscosity at high temperature (SAE 20, 30, 40, and 50). The abilities of three (3) different classification methods: regularized discriminant analysis (RDA), soft independent modelling of class analogy (SIMCA), and multilayer perceptron (MLP) - were also compared. In all cases NIR spectroscopy was found to be quite effective for motor oil classification. MLP classification technique was found to be the most effective one. 相似文献
6.
The objective of the present work is to further explore the problem of selection of the flow stress function which will give the best agreement with experiments for a wide range of the Zener‐Hollomon parameter. Analysis of various flow stress functions was performed, with particular emphasis on the Zerilli‐Armstrong model. Inverse analysis was successfully applied to identify the flow stress model for microalloyed steels deformed in ferrite, two‐phase and austenite regions. Inverse method is applied to interpret the results of the axisymmetrical compression tests performed for HSLA steel samples on a Gleeble 3800 and Split Hopkinson Pressure Bar. Sensitivity analysis is performed based on local and global methods. The objective of the sensitivity analysis in the present study is the evaluation to what extent the selected coefficients in the rheological model influence the result of simulations. In the considered tests this result is represented by two dependent variables, the load and the shape of the sample (barrelling). It is confirmed that the Zerilli‐Armstrong equations should be applied at very high strain rates. Physical meaning is an advantage of this model. Difficulties with identification are the main disadvantage. 相似文献
7.
B. P. Zhilkin I. D. Larionov A. N. Shuba 《Instruments and Experimental Techniques》2004,47(4):545-547
A device containing a temperature converter with an infrared camera is described. Its application allows one to instantly measure the temperature field of a gas flow in regions of arbitrary sizes. 相似文献
8.
The proposed mode of consideration of the steel-concrete interaction (Part I) is applied to real-life engineering structures. Two structures recently investigated numerically at Vienna University of Technology are considered: (1) the reinforced concrete (RC) cooling tower III Ptolema?s SES (Greece) and (2) a part of the shotcrete tunnel lining installed at the Lainzer tunnel (Austria). In both examples, the uniaxial fracture criterion used in Part I is replaced by the maximum stress (Rankine) criterion. Together with the Drucker-Prager criterion, which is used for the simulation of compressive failure of concrete/shotcrete, it defines the space of admissible stress states in the framework of multisurface plasticity. For the simulation of early-age fracture of shotcrete, consideration of the steel-concrete interaction presented in Part I of this paper is extended towards young shotcrete. Similar to the benchmark problem investigated in Part I of this paper, several analyses with different degrees of consideration of the steel-concrete interaction are performed. The obtained results give insight into the influence of the steel-concrete interaction on the load-carrying behavior of the investigated structures. 相似文献
9.
Roman S. Ingarden 《Open Systems & Information Dynamics》1992,1(1):75-102
A higher-order generalization of the usual thermodynamic formalism is presented for systems with the number of particlesN large in comparison with 1, but sufficiently small that one or many higher-order fluctuations of energy (or other observables) are measurable, directly or indirectly. Then 1 «N «N
A
, whereN
A
is the Avogadro number, andn2, wheren is the highest order of fluctuations (central statistical moments). The systems are then open, finite and compact, and they have compact boundary surfaces, so that the energy is non-additive and temperatures are non-intensive, in general. Such systems will be called comesoscopic, while a finite or infinite super-system of such systems will be called mesoscopic. Three ideal models of comesoscopic systems are discussed in detail with one or two higher-order temperatures. General conclusions concerning hierarchical composite systems are drawn afterwards.
相似文献
10.
To date, it has been reliably shown that the lipid bilayer/water interface can be thoroughly characterized by a sophisticated so-called “dynamic molecular portrait”. The latter reflects a combination of time-dependent surface distributions of various physicochemical properties, inherent in both model lipid bilayers and natural multi-component cell membranes. One of the most important features of biomembranes is their mosaicity, which is expressed in the constant presence of lateral inhomogeneities, the sizes and lifetimes of which vary in a wide range—from 1 to 103 nm and from 0.1 ns to milliseconds. In addition to the relatively well-studied macroscopic domains (so-called “rafts”), the analysis of micro- and nanoclusters (or domains) that form an instantaneous picture of the distribution of structural, dynamic, hydrophobic, electrical, etc., properties at the membrane-water interface is attracting increasing interest. This is because such nanodomains (NDs) have been proven to be crucial for the proper membrane functioning in cells. Therefore, an understanding with atomistic details the phenomena associated with NDs is required. The present mini-review describes the recent results of experimental and in silico studies of spontaneously formed NDs in lipid membranes. The main attention is paid to the methods of ND detection, characterization of their spatiotemporal parameters, the elucidation of the molecular mechanisms of their formation. Biological role of NDs in cell membranes is briefly discussed. Understanding such effects creates the basis for rational design of new prospective drugs, therapeutic approaches, and artificial membrane materials with specified properties. 相似文献