全文获取类型
收费全文 | 1276篇 |
免费 | 44篇 |
专业分类
电工技术 | 19篇 |
化学工业 | 179篇 |
金属工艺 | 16篇 |
机械仪表 | 27篇 |
建筑科学 | 40篇 |
矿业工程 | 1篇 |
能源动力 | 24篇 |
轻工业 | 219篇 |
水利工程 | 14篇 |
无线电 | 118篇 |
一般工业技术 | 175篇 |
冶金工业 | 325篇 |
原子能技术 | 4篇 |
自动化技术 | 159篇 |
出版年
2022年 | 8篇 |
2021年 | 22篇 |
2020年 | 7篇 |
2019年 | 14篇 |
2018年 | 12篇 |
2017年 | 25篇 |
2016年 | 23篇 |
2015年 | 24篇 |
2014年 | 25篇 |
2013年 | 45篇 |
2012年 | 54篇 |
2011年 | 68篇 |
2010年 | 61篇 |
2009年 | 36篇 |
2008年 | 41篇 |
2007年 | 65篇 |
2006年 | 46篇 |
2005年 | 42篇 |
2004年 | 45篇 |
2003年 | 28篇 |
2002年 | 33篇 |
2001年 | 31篇 |
2000年 | 23篇 |
1999年 | 29篇 |
1998年 | 103篇 |
1997年 | 63篇 |
1996年 | 59篇 |
1995年 | 39篇 |
1994年 | 32篇 |
1993年 | 24篇 |
1992年 | 11篇 |
1991年 | 15篇 |
1990年 | 10篇 |
1989年 | 16篇 |
1988年 | 17篇 |
1987年 | 12篇 |
1986年 | 14篇 |
1985年 | 18篇 |
1984年 | 12篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 7篇 |
1978年 | 4篇 |
1977年 | 9篇 |
1976年 | 11篇 |
1975年 | 4篇 |
1974年 | 5篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1970年 | 4篇 |
排序方式: 共有1320条查询结果,搜索用时 765 毫秒
91.
Hanne Gottliebsen Ruth Hardy Olga Lightfoot Ursula Martin 《Formal Aspects of Computing》2013,25(6):993-1016
Real number theorem proving has many uses, particularly for verification of safety critical systems and systems for which design errors may be costly. We discuss a chain of developments building on real number theorem proving in PVS. This leads from the verification of aspects of an air traffic control system, through work on the integration of computer algebra and automated theorem proving to a new tool, NRV, first presented here that builds on the capabilities of Maple and PVS to provide a verified and automatic analysis of Nichols plots. This automates a standard technique used by control engineers and greatly improves assurance compared with the traditional method of visual inspection of the Nichols plots. 相似文献
92.
Ravi Khadka Bramhananda Sapkota Luís Ferreira Pires Marten van Sinderen Slinger Jansen 《Computers in Industry》2013
Enterprise Interoperability is the ability of enterprises to interoperate in order to achieve their business goals. Although the purpose of enterprise interoperability is determined at the business level, the use of technical (IT) services to support business services implies that interoperability solutions at both the business and technical level should be aligned. This paper introduces and demonstrates the suitability of an approach based on model transformations to automate enterprise interoperability. We start by considering that a set of enterprises are willing to interoperate in the context of their individual goals. The interactions necessary for their cooperation are then properly captured in terms of a so-called choreography. Our approach allows a choreography to be mapped and transformed to an orchestration, which defines the operation of the actual technical services of the interoperating enterprises. The paper discusses the technical challenges of implementing the transformation, and illustrates our approach with two application scenarios. 相似文献
93.
Ronald J. Gelten Tonek P.J. Jansen Rutger A. van Santen Johan J. Lukkien John P.L. Segers Peter A.J. Hilbers 《Israel journal of chemistry》1998,38(4):415-428
The dynamic Monte Carlo method has been used to simulate the 2 A + B2 → 2 AB reaction catalyzed by a reconstructing substrate. Oscillatory behavior and spatio-temporal is studied as a function of grid size. Spatio-temporal pattern formation has been simulated in various forms: cellular patterns, target patterns, rotating spirals, and turbulent patterns. Cellular patterns are a manifestation of a local synchronization mechanism in which all reaction fronts periodically extinguish each other. This illustrates that dynamic Monte Carlo simulations form a promising technique and can be used to predict macroscopic kinetic phenomena on a molecular basis. 相似文献
94.
Diffuse reflectance laser flash photolysis was successfully employed to study the triplet states of dyes adsorbed on or chemically attached to cotton. This technique, together with the detection of singlet oxygen from dyes on cotton, made it possible to investigate the diffusion of oxygen in cotton fibres and the mobility of dyes adsorbed onto cotton. Absorption by the triplet states of aluminium phthalocyanine chloride and eosin and the phosphorescence of singlet oxygen produced by sensitisation with rose bengal was used to monitor oxygen diffusion and dye mobility by measuring differences in triplet lifetimes, singlet oxygen lifetimes and in signal intensities. It was found that swollen cotton allows diffusion of oxygen in the fibres. However, a noticeable effect on the triplet state of adsorbed aluminium phthalocyanine chloride is only observed if oxygen is removed or added by thorough evacuation or oxygenation of the samples over several days. Singlet oxygen was quenched dynamically by adsorbed dyes, which were found to be immobilised on the fibres, demonstrating that oxygen is mobile within the fibres at the molecular level. 相似文献
95.
96.
Hanne Hjorth Tønnesen Jan Karlsen Sitaram R. Adhikary Rita Pandey 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1989,189(2):116-118
Summary The content of curcuminoids inCurcuma longa L. before, during and after a normal harvesting period was investigated. The plant material was grown in the Kathmandu area. Bis-demethoxycurcumin was found to be the main constituent. No significant change in the curcuminoid content was observed during a 17-week sampling period.
Studien über Curcumin und Curcuminoide. XVII. Veränderung des Gehaltes an Curcuminoiden inCurcuma longa L. (Zingiberaceae) aus Nepal warend der Ernte
Zusammenfassung Der Gehalt an Curcuminoiden inCurcuma longa L. (Zingiberaceae) wurde vor, während und nach der normalen Erntezeit untersucht. Das Pflanzenmaterial stammt aus dim Kathmandu-Tal in Nepal. Der Hauptinhaltsstoff ist Bisdemethoxycurcumin. Im Laufe von 17 Wochen konnten keine signifikante Schwankungen observiert werden.相似文献
97.
Simon M. M. Pedersen Caroline Nebel Niels Chr. Nielsen Henrik J. Andersen Johan Olsson Magnus Simrén Lena Öhman Ulla Svensson Hanne C. Bertram Anders Malmendal 《European Food Research and Technology》2011,233(6):1013-1021
In the present study, the use of gas chromatography mass spectrometry (GC–MS)-based metabonomics to characterize blood serum
in an intervention study of patients suffering from the common gastrointestinal disorder irritable bowel syndrome (IBS) was
investigated. The patients included in the study consumed an acidified milk product with (n = 30) or without probiotics (n = 31) (Lactobacillus paracasei F19, Lactobacillus acidophilus LA-5 and Bifidobacterium lactis BB-12) for an 8-week period, and blood serum samples were collected before and after the intervention. Acidified milk is
commonly used as a delivering vector for probiotics in commercial consumer settings. The serum samples were extracted and
derivatized using N-Methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA), and GC–MS analysis was carried out. Multivariate data analysis including principal
component analysis (PCA), orthogonal partial least squares-discriminant analysis (OPLS-DA), and S-plot was applied on the
obtained GC–MS data, which revealed higher serum lactate, glutamine, proline creatinine/creatine, and aspartic acid levels
and lower serum glucose levels after the intervention period for both treatment groups. Consequently, the present study indicated
an effect of acidified milk consumption on the plasma metabolite profile, which was independent of a concomitant intake of
probiotics. In addition, the present study demonstrates that GC–MS is a useful analytical technique for metabonomics studies
of blood serum. 相似文献
98.
99.
Nicole M. van Dam Bao-Li Qiu Cornelis A. Hordijk Louise E. M. Vet Jeroen J. Jansen 《Journal of chemical ecology》2010,36(9):1006-1016
Plants under attack by aboveground herbivores emit complex blends of volatile organic compounds (VOCs). Specific compounds
in these blends are used by parasitic wasps to find their hosts. Belowground induction causes shifts in the composition of
aboveground induced VOC blends, which affect the preference of parasitic wasps. To identify which of the many volatiles in
the complex VOC blends may explain parasitoid preference poses a challenge to ecologists. Here, we present a case study in
which we use a novel bioinformatics approach to identify biologically relevant differences between VOC blends of feral cabbage
(Brassica oleracea L.). The plants were induced aboveground or belowground with jasmonic acid (JA) and shoot feeding caterpillars (Pieris brassicae or P. rapae). We used Partial Least Squares—Discriminant Analysis (PLSDA) to integrate and visualize the relation between plant-emitted
VOCs and the preference of female Cotesia glomerata. Overall, female wasps preferred JA-induced plants over controls, but
they strongly preferred aboveground JA-induced plants over belowground JA-induced plants. PLSDA revealed that the emission
of several monoterpenes was enhanced similarly in all JA-treated plants, whereas homoterpenes and sesquiterpenes increased
exclusively in aboveground JA-induced plants. Wasps may use the ratio between these two classes of terpenes to discriminate
between aboveground and belowground induced plants. Additionally, it shows that aboveground applied JA induces different VOC
biosynthetic pathways than JA applied to the root. Our bioinformatic approach, thus, successfully identified which VOCs matched
the preferences of the wasps in the various choice tests. Additionally, the analysis generated novel hypotheses about the
role of JA as a signaling compound in aboveground and belowground induced responses in plants. 相似文献
100.
The tensile creep fracture properties of coarse- and fine-grained dispersion-strengthened-cast aluminum (DSC-Al) with 25 vol
pct of submicron alumina dispersoids are presented for temperatures between 335 °C and 500 °C and stresses between 30 and
100 MPa. The primary, secondary, and tertiary creep strains are analyzed in terms of the minimum creep rate, applied stress,
and temperature. Good agreement with the original and the modified Monkman-Grant relationships is found for the failure time
of DSC-Al and other aluminum materials reinforced with dispersoids or particulates. The origin of the Monkman-Grant relationships
for these materials is discussed in terms of stress exponents, specific interfacial areas, and ratio of secondary strain to
failure strain. 相似文献