全文获取类型
收费全文 | 4021篇 |
免费 | 247篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 61篇 |
综合类 | 1篇 |
化学工业 | 952篇 |
金属工艺 | 90篇 |
机械仪表 | 65篇 |
建筑科学 | 106篇 |
矿业工程 | 7篇 |
能源动力 | 124篇 |
轻工业 | 394篇 |
水利工程 | 31篇 |
石油天然气 | 3篇 |
无线电 | 404篇 |
一般工业技术 | 797篇 |
冶金工业 | 449篇 |
原子能技术 | 32篇 |
自动化技术 | 757篇 |
出版年
2024年 | 7篇 |
2023年 | 41篇 |
2022年 | 105篇 |
2021年 | 130篇 |
2020年 | 100篇 |
2019年 | 113篇 |
2018年 | 120篇 |
2017年 | 112篇 |
2016年 | 142篇 |
2015年 | 134篇 |
2014年 | 178篇 |
2013年 | 250篇 |
2012年 | 255篇 |
2011年 | 318篇 |
2010年 | 232篇 |
2009年 | 202篇 |
2008年 | 213篇 |
2007年 | 193篇 |
2006年 | 192篇 |
2005年 | 123篇 |
2004年 | 118篇 |
2003年 | 96篇 |
2002年 | 81篇 |
2001年 | 67篇 |
2000年 | 50篇 |
1999年 | 50篇 |
1998年 | 152篇 |
1997年 | 91篇 |
1996年 | 61篇 |
1995年 | 48篇 |
1994年 | 37篇 |
1993年 | 41篇 |
1992年 | 23篇 |
1991年 | 21篇 |
1990年 | 14篇 |
1989年 | 14篇 |
1988年 | 11篇 |
1987年 | 13篇 |
1986年 | 13篇 |
1985年 | 13篇 |
1984年 | 8篇 |
1983年 | 8篇 |
1982年 | 11篇 |
1981年 | 15篇 |
1980年 | 5篇 |
1979年 | 11篇 |
1977年 | 8篇 |
1976年 | 7篇 |
1975年 | 4篇 |
1973年 | 6篇 |
排序方式: 共有4273条查询结果,搜索用时 15 毫秒
51.
M Onofrj T Fulgente A Thomas L Curatola M Peresson L Lopez T Locatelli V Martinelli G Comi 《Canadian Metallurgical Quarterly》1995,83(3-4):213-239
Visual evoked potentials (VEPs) to pattern reversal vertical bar stimuli were recorded from 24 scalp derivations (including zygomatic and inion) referenced to digitally linked earlobes in 50 controls. 1, 2 and 4 cpd patterns were presented as full field (FF) stimuli, on Upper Hemifields (UHF) and Lower Hemifields (LHF), upper and lower quadrants and with the occlusion of central and peripheral UHF and LHF. VEPs to octant stimuli were also recorded with 2 cpd patterns. N1, P1 and N2 components were recorded from posterior and inion derivations with FF stimuli, from posterior derivations with LHF stimuli, only from inion leads with UHF stimuli, from derivations ipsilateral to stimuli with quadrants and octants, and consistently from midline derivations only with lower quadrants. Polarity inverted sequences (iN1-iP1-iN2) were recorded from the other scalp derivations, with similar latency and spatial frequency sensitivity as N1-P1-N2. Single Equivalent Dipole (ED) calculations were performed on N1 and P1 recorded in the different stimulus conditions. Our findings contradict previous hypotheses on VEP generators and contradict the predictions of VEPs polarity and distribution based on the "cruciform model" of VEPs generators. In order to explain the distribution of VEPs to upper and lower half fields and to quadrant and octants, we propose a model based on the position of the medial and occipito-polar surface of visual cortex in man. 相似文献
52.
Applied Intelligence - Recent success in scaling deep reinforcement algorithms (DRL) to complex problems has been driven by well-designed extrinsic rewards, which limits their applicability to many... 相似文献
53.
Anticipating Cutoff Diameters in Deterministic Lateral Displacement (DLD) Microfluidic Devices for an Optimized Particle Separation 下载免费PDF全文
Eloise Pariset Catherine Pudda François Boizot Nicolas Verplanck Jean Berthier Aurélie Thuaire Vincent Agache 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(37)
Deterministic lateral displacement (DLD) devices enable to separate nanometer to micrometer‐sized particles around a cutoff diameter, during their transport through a microfluidic channel with slanted rows of pillars. In order to design appropriate DLD geometries for specific separation sizes, robust models are required to anticipate the value of the cutoff diameter. So far, the proposed models result in a single cutoff diameter for a given DLD geometry. This paper shows that the cutoff diameter actually varies along the DLD channel, especially in narrow pillar arrays. Experimental and numerical results reveal that the variation of the cutoff diameter is induced by boundary effects at the channel side walls, called the wall effect. The wall effect generates unexpected particle trajectories that may compromise the separation efficiency. In order to anticipate the wall effect when designing DLD devices, a predictive model is proposed in this work and has been validated experimentally. In addition to the usual geometrical parameters, a new parameter, the number of pillars in the channel cross dimension, is considered in this model to investigate its influence on the particle trajectories. 相似文献
54.
55.
Novel GaInSbAs/GaSb multiple-quantum-well lasers operating near room temperature have been successfully used for tunable diode laser absorption spectroscopy in the vicinity of 2.35 mum. Continuous current tuning over a more than 150-GHz frequency range has been realized. Direct absorption measurements have been carried out on the R, R, R, and R lines of carbon monoxide. Traces of carbon monoxide at the level of 0.3 part in 10(6) in volume at 100 Torr could be detected by the low-frequency wavelength-modulation technique and an astigmatic multipass cell. These results show a potential use of these diode lasers in portable low-cost trace-pollutant sensors. 相似文献
56.
J Murcia J Vazquez SM Lopez M Gamez L Hierro C Camarena A de la Vega E Frauca MC Diaz P Jara J Tovar 《Canadian Metallurgical Quarterly》1996,6(3):152-154
BACKGROUND: Biological systems that show threshold phenomena are candidates for stochastic resonance as a mechanism to explain what appears to be biovariability. Stochastic resonance is the amplification of weak signals by "noise." OBJECTIVE: This review discusses the areas of contact dermatitis in which threshold events have been documented. The purpose is to point out the mechanism by which stochastic resonance may affect patch test results. METHODS: A literature review technique was used. RESULTS: The recent finding of a neurological influence on contract dermatitis provides a mechanism for stochastic resonance to affect patch test results. CONCLUSION: Stochastic resonance is likely to affect patch test results when more than one patch test result is positive. 相似文献
57.
58.
Emmanuel Bruno Nicolas Faessel Herv�� Glotin Jacques Le Maitre Michel Scholl 《World Wide Web》2011,14(5-6):623-649
We present in this paper a model for indexing and querying web pages, based on the hierarchical decomposition of pages into blocks. Splitting up a page into blocks has several advantages in terms of page design, indexing and querying such as (i) blocks of a page most similar to a query may be returned instead of the page as a whole (ii) the importance of a block can be taken into account, as well as (iii) the permeability of the blocks to neighbor blocks: a block b is said to be permeable to a block b?? in the same page if b?? content (text, image, etc.) can be (partially) inherited by b upon indexing. An engine implementing this model is described including: the transformation of web pages into blocks hierarchies, the definition of a dedicated language to express indexing rules and the storage of indexed blocks into an XML repository. The model is assessed on a dataset of electronic news, and a dataset drawn from web pages of the ImagEval campaign where it improves by 16% the mean average precision of the baseline. 相似文献
59.
Jose Gonzalez-Mora Fernando De la Torre Nicolas Guil Emilio L. Zapata 《Image and vision computing》2010
Over the last decade 3D face models have been extensively used in many applications such as face recognition, facial animation and facial expression analysis. 3D Morphable Models (MMs) have become a popular tool to build and fit 3D face models to images. Critical to the success of MMs is the ability to build a generic 3D face model. Major limitations in the MMs building process are: (1) collecting 3D data usually involves the use of expensive laser scans and complex capture setups, (2) the number of available 3D databases is limited, and typically there is a lack of expression variability and (3) finding correspondences and registering the 3D model is a labor intensive and error prone process. 相似文献
60.