全文获取类型
收费全文 | 2661篇 |
免费 | 104篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 52篇 |
综合类 | 4篇 |
化学工业 | 658篇 |
金属工艺 | 35篇 |
机械仪表 | 52篇 |
建筑科学 | 84篇 |
能源动力 | 73篇 |
轻工业 | 213篇 |
水利工程 | 10篇 |
石油天然气 | 9篇 |
无线电 | 256篇 |
一般工业技术 | 510篇 |
冶金工业 | 273篇 |
原子能技术 | 16篇 |
自动化技术 | 523篇 |
出版年
2024年 | 4篇 |
2023年 | 21篇 |
2022年 | 41篇 |
2021年 | 74篇 |
2020年 | 33篇 |
2019年 | 56篇 |
2018年 | 67篇 |
2017年 | 63篇 |
2016年 | 74篇 |
2015年 | 78篇 |
2014年 | 95篇 |
2013年 | 129篇 |
2012年 | 149篇 |
2011年 | 209篇 |
2010年 | 137篇 |
2009年 | 139篇 |
2008年 | 146篇 |
2007年 | 120篇 |
2006年 | 127篇 |
2005年 | 106篇 |
2004年 | 107篇 |
2003年 | 63篇 |
2002年 | 75篇 |
2001年 | 59篇 |
2000年 | 37篇 |
1999年 | 47篇 |
1998年 | 103篇 |
1997年 | 74篇 |
1996年 | 57篇 |
1995年 | 45篇 |
1994年 | 30篇 |
1993年 | 22篇 |
1992年 | 21篇 |
1991年 | 17篇 |
1990年 | 16篇 |
1989年 | 18篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1982年 | 7篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1976年 | 13篇 |
1974年 | 3篇 |
1970年 | 3篇 |
1968年 | 3篇 |
排序方式: 共有2768条查询结果,搜索用时 15 毫秒
61.
P Le Guellec S Dumas GE Volle E Pidoux MS Moukhtar F Treilhou-Lahille 《Canadian Metallurgical Quarterly》1993,41(3):389-395
We report here an efficient and rapid method for the specific detection of calcitonin in tumor C-cells of medullary thyroid carcinoma (MTC). This occasionally aggressive tumor arises from the endocrine thyroid C-cells. Its principal marker is calcitonin, the predominant C-cell secretion, which is detected in patients and in our animal model by radioimmunoassay of the plasma, as well as by immunohistochemistry of thyroid tissues. Although calcitonin is easily detectable in normal C-cells, its content is greatly reduced in tumor cells owing to the disappearance of the secretory granules that store the mature peptide. This finding suggests cell dedifferentiation correlated with an increasing aggressivity of the tumor. We therefore developed a rapid detection of calcitonin mRNA by in situ hybridization on routine paraffin sections, using a synthetic oligodeoxyribonucleotide probe labeled with digoxigenin-dUTP. The reaction was detected with an anti-digoxigenin antibody conjugated with alkaline phosphatase, and the enzyme catalyzed the appearance of a dark blue color. The signal was exclusively restricted to the normal, hyperplastic, and tumor C-cells. It was specific, as increasing concentrations of the unlabeled oligonucleotide led to progressive disappearance of the reaction. Its sensitivity was slightly diminished as compared with corresponding frozen sections, but the intensity of the signal was quite acceptable. High levels of calcitonin mRNA were found in all normal and hyperplastic C-cells. They were increased in most of the tumor MTC cells, which did not correlate with the amount of intracellular peptide stores but explained the abnormally high basal levels of circulating calcitonin of the tumor-bearing rats. ISH is therefore of greater value than ICC for an early anatomopathological detection of this tumor. Our data show that the tumor cells are not "dedifferentiated." They only lack the granular compartment storing the mature peptide before exocytosis, but CT biosynthesis and the rest of the secretory process seem to be complete. Our results suggest that factors expressed in malignant C-cells affect basic cell mechanisms involved in the storage of the mature calcitonin, rather than the expression of the CALC gene. 相似文献
62.
The growth of defects called watertrees in cross-linked polyethylene power-insulated cables is poorly understood. We characterized the watertree structure on artificially aged samples. The resolution of the observations was improved by contrasting watertrees with rhodamine, a fluorescent probe and using epifluorescence microscopy. Both video-enhanced microscopy and confocal laser scanning microscopy provided evidence that watertrees are constituted of continuous microchannels. Their diameter is irregular and ranges between 0.6 and 0.2 m, and maybe less. They form a complex three-dimensional array that is accurately depicted. 相似文献
63.
The concentration profile of various dopants (germanium, phosphorus, and fluorine) in preforms and optical fibers has been obtained with a Raman microprobe. A 2-microm spatial resolution was achieved. In the case of germanium and phosphorus, the results agree quite well with those obtained with an electron microprobe. Raman spectroscopy easily detects fluorine. From measurements of various F-doped samples, diffusion of fluorine in undoped and doped silica is suggested. 相似文献
64.
Bart Goethals Dominique Laurent Wim Le Page Cheikh Tidiane Dieng 《Knowledge and Information Systems》2012,33(3):655-684
We present an approach for mining frequent conjunctive in arbitrary relational databases. Our pattern class is the simple, but appealing subclass of simple conjunctive queries. Our algorithm, called Conqueror $^+$ , is capable of detecting previously unknown functional and inclusion dependencies that hold on the database relations as well as on joins of relations. These newly detected dependencies are then used to prune redundant queries. We propose an efficient database-oriented implementation of our algorithm using SQL and provide several promising experimental results. 相似文献
65.
Élise Vareilles Michel AldanondoAurélien Codet de Boisse Thierry CoudertPaul Gaborit Laurent Geneste 《Engineering Applications of Artificial Intelligence》2012,25(1):31-47
The goal of this paper is to show how it is possible to support design decisions with two different tools relying on two kinds of knowledge: case-based reasoning operating with contextual knowledge embodied in past cases and constraint filtering that operates with general knowledge formalized using constraints. Our goals are, firstly to make an overview of existing works that analyses the various ways to associate these two kinds of aiding tools essentially in a sequential way. Secondly, we propose an approach that allows us to use them simultaneously in order to assist design decisions with these two kinds of knowledge. The paper is organized as follows. In the first section, we define the goal of the paper and recall the background of case-based reasoning and constraint filtering. In the second section, the industrial problem which led us to consider these two kinds of knowledge is presented. In the third section, an overview of the various possibilities of using these two aiding decision tools in a sequential way is drawn up. In the fourth section, we propose an approach that allows us to use both aiding decision tools in a simultaneous and iterative way according to the availability of knowledge. An example dealing with helicopter maintenance illustrates our proposals. 相似文献
66.
Khaled Metwally Laurent Robert Samuel Queste Bernard Gauthier-Manuel Chantal Khan-Malek 《Microsystem Technologies》2012,18(2):199-207
Microfluidics on foil is gaining momentum due to a number of advantages of employing thin films combined with the capability
of cost-effective high-volume manufacturing of devices. In this work, ultra-thin, flexible Y-microreactors with microchannels
of 100 μm width and 30 μm depth were fabricated in thermoplastic polymer foils. The fluidic pattern was hot roll embossed
in 125 μm thick poly-methyl-methacrylate (PMMA) and 130 μm thick cyclic-olefin-copolymer (COC) films using a dry-etched microstructured
silicon wafer as a flat embossing tool in a laminator. The sealing of the channels was performed with two different techniques,
one based on lamination of SU8 dry film resist (DFR) and the other one based on spin-coated poly-dimethylsiloxane (PDMS).
Testing of the interconnected microreactor was carried out using two dye colorant solutions to demonstrate mixing. 相似文献
67.
We propose a solution to the problem of semiglobal output regulation for nonlinear minimum-phase systems driven by uncertain exosystems that does not rely upon conventional adaptation schemes to estimate the frequency of the exogenous signals. Rather, the proposed approach relies upon regression-like arguments used to derive a nonlinear internal model able to offset the presence of an unknown number of harmonic exogenous inputs of uncertain amplitude, phase and frequency. The design methodology guarantees asymptotic regulation if the dimension of the regulator exceeds a lower bound determined by the actual number of harmonic components of the exogenous input. If this is not the case, a bounded steady-state regulation error is ensured whose amplitude, though, can be arbitrarily decreased by acting on a design parameter of the regulator. 相似文献
68.
The Self-Serv environment for Web services composition 总被引:2,自引:0,他引:2
Self-Serv aims to enable the declarative composition of new services from existing ones, the multiattribute dynamic selection of services within a composition, and peer-to-peer orchestration of composite service executions. Self-Serv adopts the principle that every service, whether elementary or composite, should provide a programmatic interface based on SOAP and the Web Service Definition Language. This does not exclude the possibility of integrating legacy applications, such as those written in CORBA, into the service's business logic. To integrate such applications, however, first requires the development of appropriate adapters. The paper considers how the mechanism for composing services in Self-Serv is based on two major concepts: the composite service and the service container. 相似文献
69.
Fothergill J.C. Montanari G.C. Stevens G.C. Laurent C. Teyssedre G. Dissado L.A. Nilsson U.H. Platbrood G. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2003,10(3):514-527
The aim of the European project "ARTEMIS" is to develop a diagnostic system for assessing aging in power cable insulation. Its first task was to make a thorough characterisation of the cable insulation before aging. This is intended to provide a background against which any changes introduced by thermo-electric aging can be identified. The aging markers derived from this initial characterisation will be considered both as diagnostic indicators in their own right, and also to develop an aging model for predictive purposes, if and when possible. This stage of the ARTEMIS programme is now complete and we will present an analysis of the results, and show how they may be correlated with the concepts proposed in aging theories. 相似文献
70.
This paper reports on the creation of interactive computer installations that combine artificial life and real life by means
of human-computer interactions. These installations have focused on real-time interactions and evolutionary image processes.
Accordingly, visitors to the installations become essential parts of the systems by transmitting their individual behaviors,
emotions, and personalities to the image processes of the work. Images in these installations are no longer static, pre-fixed,
and predictable, but become “living systems” themselves, representing minute changes in the viewers' interactions with the
evolutionary image processes. Natural evolution has brought about a vast variety of forms and structures in nature. This research
considers how artificial evoluation can function as a tool of the visual creation process; design should no longer be done
by a designer or artist, but should emerge through the evolutionary image process itself. 相似文献