全文获取类型
收费全文 | 43666篇 |
免费 | 2009篇 |
国内免费 | 61篇 |
专业分类
电工技术 | 319篇 |
综合类 | 45篇 |
化学工业 | 7884篇 |
金属工艺 | 774篇 |
机械仪表 | 819篇 |
建筑科学 | 1336篇 |
矿业工程 | 89篇 |
能源动力 | 851篇 |
轻工业 | 6100篇 |
水利工程 | 392篇 |
石油天然气 | 189篇 |
武器工业 | 4篇 |
无线电 | 2443篇 |
一般工业技术 | 7517篇 |
冶金工业 | 10805篇 |
原子能技术 | 211篇 |
自动化技术 | 5958篇 |
出版年
2023年 | 364篇 |
2022年 | 382篇 |
2021年 | 937篇 |
2020年 | 775篇 |
2019年 | 703篇 |
2018年 | 1551篇 |
2017年 | 1552篇 |
2016年 | 1612篇 |
2015年 | 1144篇 |
2014年 | 1478篇 |
2013年 | 2827篇 |
2012年 | 2516篇 |
2011年 | 2331篇 |
2010年 | 1852篇 |
2009年 | 1650篇 |
2008年 | 1895篇 |
2007年 | 1676篇 |
2006年 | 1266篇 |
2005年 | 1048篇 |
2004年 | 980篇 |
2003年 | 868篇 |
2002年 | 780篇 |
2001年 | 498篇 |
2000年 | 494篇 |
1999年 | 663篇 |
1998年 | 3473篇 |
1997年 | 2089篇 |
1996年 | 1361篇 |
1995年 | 797篇 |
1994年 | 677篇 |
1993年 | 667篇 |
1992年 | 225篇 |
1991年 | 239篇 |
1990年 | 229篇 |
1989年 | 223篇 |
1988年 | 199篇 |
1987年 | 177篇 |
1986年 | 194篇 |
1985年 | 226篇 |
1984年 | 194篇 |
1983年 | 142篇 |
1982年 | 168篇 |
1981年 | 188篇 |
1980年 | 170篇 |
1979年 | 138篇 |
1978年 | 127篇 |
1977年 | 216篇 |
1976年 | 448篇 |
1975年 | 96篇 |
1973年 | 89篇 |
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
121.
Héctor J. Sussmann 《Theory of Computing Systems》1978,12(1):371-393
A universal input is an inputu with the property that, whenever two states give rise to a different output for some input, then they give rise to a different output foru. For an observable system,u is universal if the initial state can be reconstructed from the knowledge of the output foru. It is shown that, for continuous-time analytic systems, analytic universal inputs exist, and that, in the class ofC
inputs, universality is a generic property. Stronger results are proved for polynomial systems. 相似文献
122.
A short-term test to determine renal concentrating ability without any water deprivation has been described. It consists of osmolatity determinations in three onehour urine portions from spontaneous voidings following an intranasal application of 7 microng of the synthetic analogue of vasopressin-DDAVP per 0,5 m2 body surface. The values of maximal urine osmalatity over 900 mosm/Kg H2O following DDAVP are considered normal whereas values under 600 mosm are consistent with impaired renal function. If, however, the maximal urine osmolality is in the so called "uncertain range" i.e. from 600 to 900 mosm, it is advisable to perform in the same patients also the classical concentration test based on a prolonged dehydration (26 h). 相似文献
123.
124.
125.
Javier Galbally Julian Fierrez Javier Ortega-Garcia Réjean Plamondon 《Pattern recognition》2012,45(7):2622-2632
A novel method for the generation of synthetic on-line signatures based on the spectral analysis and the Kinematic Theory of rapid human movements, was presented in Part I of this series of two papers. In the present paper, the experimental framework used for the validation of the novel approach is described. The validation protocol, which uses different development and test sets in order to achieve unbiased results, includes the comparison of real and synthetic databases in terms of (i) visual appearance, (ii) statistical information, and (iii) performance evaluation of three competitive and totally different verification systems. The experimental results show the high similarity existing between synthetically generated and humanly produced samples, and the great potential of the method for the study of the signature trait. 相似文献
126.
Miguel JM Boquete L Ortega S Cordero CA Barea R Blanco R 《Computer methods and programs in biomedicine》2012,108(1):377-387
The multifocal electroretinography technique consists of performing sectorized light excitation of the retina and capturing the resulting evoked potential. This provides functional localized information about the state of the retinal neurons. Analysis of multifocal electroretinography signals can be used for diagnosing different types of optic neuropathies (glaucomatous, demyelinating and ischemic ethiology). In order to obtain a reliable diagnosis, it is necessary to apply advanced processing algorithms (morphological, frequency and time-frequency analysis, etc.) to the multifocal electroretinography signal. This paper presents a software application developed in MATLAB(?) (MathWorks Inc., MA) designed to perform advanced multifocal electroretinography signal analysis and classification. This intuitive application, mfERG_LAB, is used to plot the signals, apply various algorithms to them and present the data in an appropriate format. The application's computational power and modular structure make it suitable for use in clinical settings as a powerful and innovative diagnostic tool, as well as in research and teaching settings as a means of assessing new algorithms. 相似文献
127.
128.
Overall performance measurement in a supply chain: towards a supplier-prime manufacturer based model
This study deals with the supply chain (SC) overall performance expression. The developed idea concerns more particularly the performance of the manufactured products. Indeed, two companies or more contribute to the manufacturing of products that are generally assembled by the prime manufacturer company. Moreover, in the industrial practice, performance scorecards are defined with regard to each process; and the overall performance is neither expressed for each company, nor for the whole SC. We propose here to identify the SC overall performance to the combination of the performances of the different involved companies in the SC. Thus, in order to obtain a definition of such performance, we choose to focus first on the performance of the prime manufacturer. In this sense, the approach is based on the SCOR model for the handling of the main processes around the considered product manufacturing. The prime manufacturer performance is then defined as the aggregation of its involved processes?? performances. While the prime manufacturer performance is strongly dependent on the suppliers?? performance, we suggest the integration of the impacting supplier performance into the prime manufacturer scorecards. From an operational point of view, the MACBETH methodology is used to coherently express both processes and overall performances. More precisely, the Choquet aggregation integral operator is applied in order to model mutual interactions between processes. Finally, the expression of a bearing??s manufacturer performance illustrates the proposition. 相似文献
129.
Single crystals of 4-dimethylamino β-nitrostyrene (DMNS) were grown from solution by a falling temperature technique. Growth conditions are given. The quality of crystals obtained was studied by X-ray diffraction methods. 相似文献
130.
Bovine immunoglobulins (IgG1 type) have been isolated from colostral whey. Hydrolysis by pronase, trypsin and (or) chymotrypsin yield several glycopeptides structural studies of which lead to the following results. 1. IgG1 colostral immunoglobulins possess two glycan moieties which are linked to the peptidic chain by an N-(beta-aspartyl)-N-acetylglucosaminylamine bound. 2. The peptidic sequence around the linkage region has been determined by classical methods and is as follows: Thr-Lys-Pro-Arg-Glu-Glu-Gln-Phe-Asn(Glycan)-Ser-Thr-Tyr-Arg. 3. The following procedures: partial acidic hydrolysis, periodic oxidation, hydrazinolysis-nitrous deamination, methylation and use of specific glycosidases allowed us to determine the structure of the glycan moieties which fit with the general following scheme: (see article) Thus they could be related to the general glycan structure so-called of "N-acetyllactosamine type" because they possess the pentasaccharidic core common to numerous glycoproteins Man alpha 1 leads to [Man alpha 1 leads to 6] Man beta 1 leads to 4 GlcNAc beta 1 leads to 4 GlcNAc beta 1 leads to Asn on which are conjugated 2 N-acetyllactosamine residues. Besides they present a microheterogeneity which is due to the varying number of additional N-acetylneuraminic acid and fucose residues. 4. These structures are compared to various immunoglobulin structures proposed by others: bovine serum IgG and human serum IgG, IgE and IgA. 相似文献