全文获取类型
收费全文 | 1153篇 |
免费 | 53篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 11篇 |
综合类 | 3篇 |
化学工业 | 285篇 |
金属工艺 | 17篇 |
机械仪表 | 13篇 |
建筑科学 | 66篇 |
矿业工程 | 1篇 |
能源动力 | 19篇 |
轻工业 | 109篇 |
水利工程 | 5篇 |
石油天然气 | 3篇 |
无线电 | 103篇 |
一般工业技术 | 200篇 |
冶金工业 | 178篇 |
原子能技术 | 6篇 |
自动化技术 | 190篇 |
出版年
2023年 | 6篇 |
2022年 | 16篇 |
2021年 | 37篇 |
2020年 | 13篇 |
2019年 | 14篇 |
2018年 | 24篇 |
2017年 | 27篇 |
2016年 | 26篇 |
2015年 | 31篇 |
2014年 | 48篇 |
2013年 | 89篇 |
2012年 | 59篇 |
2011年 | 81篇 |
2010年 | 59篇 |
2009年 | 60篇 |
2008年 | 67篇 |
2007年 | 63篇 |
2006年 | 53篇 |
2005年 | 25篇 |
2004年 | 38篇 |
2003年 | 37篇 |
2002年 | 32篇 |
2001年 | 19篇 |
2000年 | 17篇 |
1999年 | 19篇 |
1998年 | 19篇 |
1997年 | 8篇 |
1996年 | 20篇 |
1995年 | 17篇 |
1994年 | 16篇 |
1993年 | 11篇 |
1992年 | 6篇 |
1991年 | 9篇 |
1990年 | 9篇 |
1989年 | 7篇 |
1988年 | 10篇 |
1987年 | 11篇 |
1986年 | 4篇 |
1985年 | 9篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1978年 | 7篇 |
1977年 | 4篇 |
1975年 | 10篇 |
1973年 | 3篇 |
1961年 | 3篇 |
1956年 | 3篇 |
排序方式: 共有1209条查询结果,搜索用时 15 毫秒
91.
Parenting style as context: An integrative model. 总被引:1,自引:0,他引:1
Despite broad consensus about the effects of parenting practices on child development, many questions about the construct parenting style remain unanswered. Particularly pressing issues are the variability in the effects of parenting style as a function of the child's cultural background, the processes through which parenting style influences the child's development, and the operationalization of parenting style. Drawing on historical review, the authors present a model that integrates 2 traditions in socialization research, the study of specific parenting practices and the study of global parent characteristics. They propose that parenting style is best conceptualized as a context that moderates the influence of specific parenting practices on the child. It is argued that only by maintaining the distinction between parenting style and parenting practice can researchers address questions concerning socialization processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
92.
The formation of hydrous oxide films on gold in base under potential cycling conditions was investigated and found to be less inhibited than the same type of reaction observed when gold is strongly anodized at high potentials under d.c. conditions at high pH. The overall behaviour on cycling is quite similar to that observed with other metals, e.g. platinum. The importance of the lower limit, for instance, again appears to be related to the need under film thickening conditions to significantly reduce the compact oxide layer formed on the metal surface during the anodic sweep. It was noted that the earlier duplex model for this type of system, i.e. an inner compact and an outer dispersed oxide layer, is not always valid. Under certain conditions about six distinct peaks (suggesting six different states of gold oxide hydration, dispersion or polymerization) were observed in cathodic sweeps recorded for the reduction of thick films grown on gold under potential cycling conditions in base. 相似文献
93.
94.
95.
The main objective of the paper is to point out the influence of composition and of poling state (poled and unpoled samples) on the evolution of various parameters (?r, dilatation coefficients, lattice parameters) at different scales (lattice, bulk) using X-ray diffraction (XRD), thermo-mechanical analysis (TMA) and dielectric methods. The transition temperatures have been determined from the above measurements and compared. The composition has an influence on the transition temperature and not on the dilatation coefficient value. The poling state influences only the macroscopic dilatation evolution and not the value of the transition temperature. A scale effect is only observed on majoritary tetragonal compositions which show different values of transition temperatures from microscopic and macroscopic methods. 相似文献
96.
97.
Bert J. Campo David Bevk Jurgen Kesters Jan Gilot Henk J. Bolink Jun Zhao Jean-Christophe Bolsée Wibren D. Oosterbaan Sabine Bertho Jan D’Haen Jean Manca Laurence Lutsen Guy Van Assche Wouter Maes René A.J. Janssen Dirk Vanderzande 《Organic Electronics》2013,14(2):523-534
The introduction of functional moieties in the donor polymer (side chains) offers a potential pathway toward selective modification of the nanomorphology of conjugated polymer:fullerene active layer blends applied in bulk heterojunction organic photovoltaics, pursuing morphology control and solar cell stability. For this purpose, two types of poly(3-alkylthiophene) random copolymers, incorporating different amounts (10/30/50%) of ester-functionalized side chains, were efficiently synthesized using the Rieke method. The solar cell performance of the functionalized copolymers was evaluated and compared to the pristine P3HT:PCBM system. It was observed that the physicochemical and opto-electronic characteristics of the polythiophene donor material can be modified to a certain extent via copolymerization without (too much) jeopardizing the OPV efficiency, as far as the functionalized side chains are introduced in a moderate ratio (<30%) and that preference is given to side chains with a small molar volume. A range of complementary techniques – UV–Vis spectroscopy, (modulated temperature) differential scanning calorimetry, transmission electron microscopy and X-ray diffraction analysis – indicated that variations in polymer crystallinity, while maintaining a high level of regioregularity, are probably the main factor responsible for the observed differences. 相似文献
98.
Guéguin M Roux E Hernández AI Porée F Mabo P Graindorge L Carrault G 《IEEE transactions on bio-medical engineering》2008,55(10):2343-2352
Current cardiac implantable devices (IDs) are equipped with a set of sensors that can provide useful information to improve patient follow-up and prevent health deterioration in the postoperative period. In this paper, data obtained from an ID with two such sensors (a transthoracic impedance sensor and an accelerometer) are analyzed in order to evaluate their potential application for the follow-up of patients treated with a cardiac resynchronization therapy (CRT). A methodology combining spatiotemporal fuzzy coding and multiple correspondence analysis (MCA) is applied in order to: 1) reduce the dimensionality of the data and provide new synthetic indexes based on the "factorial axes" obtained from MCA; 2) interpret these factorial axes in physiological terms; and 3) analyze the evolution of the patient's status by projecting the acquired data into the plane formed by the first two factorial axes named "factorial plane." In order to classify the different evolution patterns, a new similarity measure is proposed and validated on the simulated datasets, and then, used to cluster observed data from 41 CRT patients. The obtained clusters are compared with the annotations on each patient's medical record. Two areas on the factorial plane are identified, one being correlated with a health degradation of patients and the other with a stable clinical state. 相似文献
99.
In their article ( https://doi.org/10.1002/adfm.201703511 ), Bojnicic‐Kninski et al. expose the known methods used for creating, on a same substrate, patterns composed of different types of particles. This approach is called “combinatorial particle patterning.” They describe various techniques and group them depending on the used methods or driving forces that enable the directed assemblies of particles. A substantial part of the article (Part 2: Electrical Particle Patterning) referred to particle assemblies guided by electrostatic forces, i.e., electrophoretic or dielectrophoretic forces. However, this part, especially the paragraph on “Nanoxerography” (cf. 2.2 of the article) suffers from some inaccuracies that lead to partially wrong conclusions regarding combinatorial particle patterning. The goal of this comment is double: i) giving a complete and up to date definition of nanoxerography ii) reporting the results on combinatorial particle patterning using nanoxerography to correct the article inaccuracies. 相似文献
100.
Yushi Shen Pamela C Cosman Laurence B Milstein 《IEEE transactions on image processing》2006,15(11):3241-3252
We present an adaptive video transmission scheme for use in a code-division multiple-access network, which incorporates efficient bandwidth allocation among source coding, channel coding, and spreading under a fixed total bandwidth constraint. We derive the statistics of the received signal, as well as a theoretical bound on the packet drop rate at the receiver. Based on these results, a bandwidth allocation algorithm is proposed at the packet level, which incorporates the effects of both the changing channel conditions and the dynamics of the source content. Detailed simulations are done to evaluate the performance of the system, and the sensitivity of the system to estimation error is presented. 相似文献