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111.
M. Del C. Ruiz J. A. González J. B. Rivarola 《Metallurgical and Materials Transactions B》2004,35(3):439-448
The mechanism and kinetics of β-Ta2O5 chlorination, mixed with sucrose carbon, have been studied by a thermogravimetric technique. The investigated temperature
range was 500 °C to 850 °C. The reactants and reaction residues were analyzed by scanning electronic microscopy (SEM), X-ray
diffraction (XRD), and Brunauer-Emmett-Teller method for surface area (BET). The effect of various experimental parameters
was studied, such as carbon percentage, temperature, chlorine partial pressure, and flow, use of the multiple sample method,
and carbon previous oxidation. The carbon percentage and previous treatment have an effect on the system reactivity. The temperature
has a marked effect on the reaction rate. In the 500 °C to 600 °C temperature interval, the apparent activation energy is
144 kJ/mol of oxide, while at higher temperatures, the activation energy decreases. With high chorine partial pressures, the
order of reaction is near zero. The kinetic contractile plate model, X=kt, considering carbon oxidation as the controlling stage, is the one with the best fit to the experimental data. A probable
mechanism for the carbochlorination of β-Ta2O5 is proposed: (1) activation of chlorine on the carbon surface, (2) chlorination of Ta2O5, (3) oxidation of carbon, and (4) recrystallization of β-Ta2O5. 相似文献
112.
113.
In this paper we consider two performance modelling techniques from the perspectives of model construction, generation of
an underlying continuous time Markov process, and the potential for reduction in the Markov process. Such careful comparison
of modelling techniques allows us to appreciate the strengths and weaknesses of different approaches, and facilitates cross-fertilization
between them. In the present case we take a characteristic of one formalism, functional rates in Stochastic Automata Networks,
and introduce it to the other formalism, Performance Evaluation Process Algebra. We investigate the benefits of this cross-fertilization,
particularly from the perspectives of Markov process generation and reduction. 相似文献
114.
115.
With increasing globalization, communication across language and cultural boundaries is becoming an essential requirement
of doing business, delivering education, and providing public services. Due to the considerable cost of human translation
services, only a small fraction of text documents and an even smaller percentage of spoken encounters, such as international
meetings and conferences, are translated, with most resorting to the use of a common language (e.g. English) or not taking
place at all. Technology may provide a potentially revolutionary way out if real-time, domain-independent, simultaneous speech
translation can be realized. In this paper, we present a simultaneous speech translation system based on statistical recognition
and translation technology. We discuss the technology, various system improvements and propose mechanisms for user-friendly
delivery of the result. Over extensive component and end-to-end system evaluations and comparisons with human translation
performance, we conclude that machines can already deliver comprehensible simultaneous translation output. Moreover, while
machine performance is affected by recognition errors (and thus can be improved), human performance is limited by the cognitive
challenge of performing the task in real time. 相似文献
116.
Anastassios Pouris 《Scientometrics》2007,70(3):541-553
This article reports the findings of a scientometric analysis of nanoscale research in South Africa during the period 2000–2005.
The ISI databases were identified as the most appropriate information platform for the objectives of the investigation and
have been interrogated for the identification of South African authors publishing in the field.
The article identifies trends over time, major institutional contributors, journals in which South African authors publish
their research, international collaborators and performance in comparison to four comparator countries (India, Brazil, South
Korea and Australia). The major findings of the investigation are as follows: nanoscale research in South Africa is driven
by individual researchers interests up to date and it is in its early stages of development; the country’s nanoscale research
is below what would one expect in light of its overall publication output; the country’s nano-research is distributed to a
number of Universities with subcritical concentration of researchers. 相似文献
117.
Bibliometric analysis of tsunami research 总被引:3,自引:0,他引:3
The use of the bibilometric analytical technique for examining tsunami research does not exist in the literature. The objective
of the study was to perform a bibliometric analysis of all tsunami-related publications in the Science Citation Index (SCI).
Analyzed parameters included document type, language of publication, publication output, authorship, publication patterns,
distribution of subject category, distribution of author keywords, country of publication, most-frequently cited article,
and document distribution after the Indonesia tsunami. The US and Japan produced 53% of the total output where the seven major
industrial countries accounted for the majority of the total production. English was the dominant language, comprising 95%
of articles. A simulation model was applied to describe the relationship between the number of authors and the number of articles,
the number of journals and the number of articles, and the percentage of total articles and the number of times a certain
keyword was used. Moreover the tsunami publication patterns in the first 8 months after the Indonesia tsunami occurred on
26 December 2004 indicated a high percentage of non-article publications and more documents being published in journals with
higher impact factors. 相似文献
118.
119.
Remigiusz Sapa 《Scientometrics》2007,71(3):473-493
This article reports findings from the study of the international contribution to the system of library and information science
communication in Poland in the years 2003–2005. The sample consists of articles published both in selected journals and collective
works. Two important dimensions determining the internationalization of local scholarly communication are considered: direct
contribution (foreign authors’ articles and papers and their translations published in Poland) and indirect contribution (citedness
of foreign authors’ documents in articles and papers published in Poland). Bibliographic data about the geographical distribution
and affiliation of foreign authors are gathered and analyzed. Furthermore, the findings of citation analysis are presented
to determine the percentage share of citations received by foreign documents as well as to find out what is the structure
of such citations regarding the language and form, which thematic areas are most replete with such citations and which foreign
journals are most cited in Poland. 相似文献
120.
Joachim Schummer 《Scientometrics》2007,70(3):669-692
Based on bibliometric methods, this paper describes the global institutionalization of nanotechnology research from the mid-1980s
to 2006. Owing to an extremely strong dynamics, the institutionalization of nanotechnology is likely to surpass those of major
disciplines in only a few years. A breakdown of the relative institutionalizations strengths by the main geographical regions,
countries, research sectors, disciplines, and institutional types provides a very diverse picture over the time period because
of different national science policies. The results allow a critical assessment of the different science policies based on
the relative institutionalizations strengths as well as the conclusion that the institutionalization process has run out of
control of individual governments who once induced the development. 相似文献