全文获取类型
收费全文 | 1304篇 |
免费 | 66篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 23篇 |
综合类 | 1篇 |
化学工业 | 498篇 |
金属工艺 | 31篇 |
机械仪表 | 42篇 |
建筑科学 | 28篇 |
矿业工程 | 2篇 |
能源动力 | 43篇 |
轻工业 | 113篇 |
水利工程 | 5篇 |
石油天然气 | 3篇 |
无线电 | 69篇 |
一般工业技术 | 235篇 |
冶金工业 | 55篇 |
原子能技术 | 7篇 |
自动化技术 | 219篇 |
出版年
2023年 | 13篇 |
2022年 | 60篇 |
2021年 | 77篇 |
2020年 | 31篇 |
2019年 | 42篇 |
2018年 | 55篇 |
2017年 | 35篇 |
2016年 | 70篇 |
2015年 | 51篇 |
2014年 | 77篇 |
2013年 | 117篇 |
2012年 | 69篇 |
2011年 | 122篇 |
2010年 | 72篇 |
2009年 | 53篇 |
2008年 | 57篇 |
2007年 | 60篇 |
2006年 | 40篇 |
2005年 | 39篇 |
2004年 | 29篇 |
2003年 | 19篇 |
2002年 | 16篇 |
2001年 | 15篇 |
2000年 | 11篇 |
1999年 | 10篇 |
1998年 | 13篇 |
1997年 | 21篇 |
1996年 | 11篇 |
1995年 | 7篇 |
1994年 | 9篇 |
1993年 | 7篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1977年 | 3篇 |
1976年 | 7篇 |
1975年 | 2篇 |
1965年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有1374条查询结果,搜索用时 0 毫秒
41.
Ivana Stachová Ivona Lhotská Petr Solich 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2016,33(7):1139-1146
Beer is one of the most popular alcoholic beverages worldwide. For consumer acceptance, significant factors are its taste, flavour and colour. This study determines selected synthetic green, blue and yellow food colorants in popular Easter herb-coloured green beers on tap produced in breweries on Holy Thursday. The abuse of beer colouring with Tartrazine (E 102), Quinoline yellow (E 104), Sunset yellow (E 110), Patent blue (E 131), Indigo carmine (E 132), Brilliant blue FCF (E 133), Green S (E 142) and Fast green FCF (E 143) was assessed in 11 green beer samples purchased in local restaurants. HPLC was used for the separation and detection of artificial colorants with diode-array detection and a Chromolith Performance CN 100 × 4.6 mm column with guard pre-column Chromolith CN 5 × 4.6 mm. Separation was performed in gradient elution with mobile phase containing methanol–aqueous 2% ammonium acetate at pH 7.0. The study showed that eight beers (70%) marketed in the Czech Republic contained artificial colorants (Tartrazine and Brilliant blue FCF). The concentration of colorants found in analysed green herb-coloured beers ranged from 1.58 to 3.49 mg l–1 for Tartrazine, 0.45–2.18 mg l–1 for Brilliant blue, while Indigo carmine was detected only once at concentration 2.36 mg l–1. Only three beers showed no addition of the synthetic colorants. However, the levels of artificial colorants found in beers marketed in the Czech region were very low and did not show a serious risk for consumers’ health. 相似文献
42.
Three‐dimensional modeling of porosity development during the gasification of a char particle 下载免费PDF全文
Kay Wittig Petr A. Nikrityuk Sebastian Schulze Andreas Richter 《American Institute of Chemical Engineers》2017,63(5):1638-1647
This work is devoted to the three‐dimensional, direct modeling of porosity and specific surface development during the gasification of a char particle. The model was developed for heterogeneous reactions occurring inside a char particle in a kinetically controlled regime. The main goal of this work is to analyze the impact of different pore size distributions on the particle carbon conversion rate. In particular, it is shown that under certain conditions the outer particle surface can influence the specific surface area. In this context the possible adaptation of the parameter ψ from the random pore model (RPM) developed by Bhatia and Perlmutter is explained. The results of simulations are compared against the RPM and discussed. Additionally, based on the results of simulations, the physics behind several input parameters used by the RPM are explored. Finally, the possible fragmentation of a chemically reacting char particle during its gasification in dependence of instantaneous porosity was investigated numerically. It was shown that the earliest fragmentation occurs at a carbon conversion of about 0.5–0.6 due to the disaggregation of the pore walls. The results are discussed and compared implicitly with data published in the literature. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1638–1647, 2017 相似文献
43.
Markta Kadle
kov Kateina Skopalov Barbora Ptokov Erik Wrzecionko Elika Daov Karolína Kocourkov Ale Mr
ek Lenka Musilov Petr Smolka Petr Humpolí
ek Antonín Minaík 《International journal of molecular sciences》2022,23(5)
The pseudo 3D hierarchical structure mimicking in vivo microenvironment was prepared by phase separation on tissue culture plastic. For surface treatment, time-sequenced dosing of the solvent mixture with various concentrations of polymer component was used. The experiments showed that hierarchically structured surfaces with macro, meso and micro pores can be prepared with multi-step phase separation processes. Changes in polystyrene surface topography were characterized by atomic force microscopy, scanning electron microscopy and contact profilometry. The cell proliferation and changes in cell morphology were tested on the prepared structured surfaces. Four types of cell lines were used for the determination of impact of the 3D architecture on the cell behavior, namely the mouse embryonic fibroblast, human lung carcinoma, primary human keratinocyte and mouse embryonic stem cells. The increase of proliferation of embryonic stem cells and mouse fibroblasts was the most remarkable. Moreover, the embryonic stem cells express different morphology when cultured on the structured surface. The acquired findings expand the current state of knowledge in the field of cell behavior on structured surfaces and bring new technological procedures leading to their preparation without the use of problematic temporary templates or additives. 相似文献
44.
Dmitry Oshchepkov Irina Chadaeva Rimma Kozhemyakina Karina Zolotareva Bato Khandaev Ekaterina Sharypova Petr Ponomarenko Anton Bogomolov Natalya V. Klimova Svetlana Shikhevich Olga Redina Nataliya G. Kolosova Maria Nazarenko Nikolay A. Kolchanov Arcady Markel Mikhail Ponomarenko 《International journal of molecular sciences》2022,23(5)
45.
Jan Bartovský Petr Dokládal Matthieu Faessel Eva Dokladalova Michel Bilodeau 《Journal of Real-Time Image Processing》2018,15(4):775-786
This paper focuses on the development of a fully programmable morphological coprocessor for embedded devices. It is a well-known fact that the majority of morphological processing operations are composed of a (potentially large) number of sequential elementary operators. At the same time, the industrial context induces a high demand on robustness and decision liability that makes the application even more demanding. Recent stationary platforms (PC, GPU, clusters) no more represent a computational bottleneck in real-time vision or image processing applications. However, in embedded solutions such applications still hit computational limits. The morphological co-processing unit (MCPU) replies to this demand. It assembles the previously published efficient dilation/erosion units with geodesic units and ALUs to support a larger collection of morphological operations, from a simple dilation to serial filters involving a geodesic reconstruction step. The coprocessor has been integrated into an FPGA platform running a server that is able to respond to client’s requests over the ethernet. The experimental performance of the MCPU measured on a wide set of operations brings as results in orders of magnitude better than another embedded platform, built around an ARM A9 quad-core processor. 相似文献
46.
Although regional price levels should be accounted for in any analysis of well-being in regions, the European Union fails to reflect them because they are not currently available for most EU member states. To fill this gap, we estimate regional price levels for all EU regions on the basis of available regional price level data from six EU countries. Once socio-economic indicators are recalculated using our estimates, substantially higher differences in living standards emerge. These results also have important implications for the European cohesion policy, with 9% of regions currently misclassified as a consequence of regional price levels not being used. 相似文献
47.
This work focuses mainly about swelling and rheological properties of calcium phosphate filled bacterial cellulose (BC)-based hydrogel scaffolds. Calcium phosphate is incorporated in the form of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) in different ratios, that is, 00:00, 10:90, 20:80, 40:60, 50:50, and 60:40. These scaffolds are also comprised with polyvinylpyrrolidone (PVP), poly(ethylene glycol), agar, and glycerin; designated as “BC-PVP” and “BC-PVP-β-TCP/HA.” All the hydrogel scaffolds are showing the notable viscoelastic property at 28 and 37 °C temperatures. The degree of swelling is found significant in BC-PVP-β-TCP/HA_50:50 scaffold and it is notably elastic at 37 °C after 5 min of swelling. However, after 60 min of swelling and at equilibrium swelling state, the elastic property of BC-PVP-β-TCP/HA_20:80 is revealed the highest. Considering the degree of swelling and rheological properties, the BC-PVP-β-TCP/HA_50:50 and BC-PVP-β-TCP/HA_20:80 hydrogel scaffolds found suitable for their application in bone tissue engineering or bone tissue regeneration. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48522. 相似文献
48.
Ivan Rehor Jitka Slegerova Jan Kucka Vladimir Proks Vladimira Petrakova Marie‐Pierre Adam François Treussart Stuart Turner Sara Bals Pavel Sacha Miroslav Ledvina Amy M. Wen Nicole F. Steinmetz Petr Cigler 《Small (Weinheim an der Bergstrasse, Germany)》2014,10(6):1106-1115
High pressure high temperature (HPHT) nanodiamonds (NDs) represent extremely promising materials for construction of fluorescent nanoprobes and nanosensors. However, some properties of bare NDs limit their direct use in these applications: they precipitate in biological solutions, only a limited set of bio‐orthogonal conjugation techniques is available and the accessible material is greatly polydisperse in shape. In this work, we encapsulate bright 30‐nm fluorescent nanodiamonds (FNDs) in 10–20‐nm thick translucent (i.e., not altering FND fluorescence) silica shells, yielding monodisperse near‐spherical particles of mean diameter 66 nm. High yield modification of the shells with PEG chains stabilizes the particles in ionic solutions, making them applicable in biological environments. We further modify the opposite ends of PEG chains with fluorescent dyes or vectoring peptide using click chemistry. High conversion of this bio‐orthogonal coupling yielded circa 2000 dye or peptide molecules on a single FND. We demonstrate the superior properties of these particles by in vitro interaction with human prostate cancer cells: while bare nanodiamonds strongly aggregate in the buffer and adsorb onto the cell membrane, the shell encapsulated NDs do not adsorb nonspecifically and they penetrate inside the cells. 相似文献
49.
Tillmann Barbara; Janata Petr; Birk Jeffrey; Bharucha Jamshed J. 《Canadian Metallurgical Quarterly》2003,29(2):470
Harmonic priming studies have shown that a musical context, with its established tonal center, influences target chord processing. This study investigated costs and benefits of priming tonal centers for target processing by adding a baseline condition (sequences without a specific tonal center). Results confirmed harmonic priming, with faster processing for related than for unrelated and less related targets (tonic chord, out-of-key chord, subdominant chord). Comparing targets in baseline contexts with targets in sequences with well-established tonal centers revealed a benefit of processing for related targets but a cost of processing for unrelated and less related targets. Findings are discussed in terms of tonal knowledge activation and suggest that an activated tonal center gives rise to strong expectations for the tonic. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
50.
Anna Siskova Jan Kral Jana Drabova Klara Cervena Kristyna Tomasova Jiri Jungwirth Tomas Hucl Pavel Kohout Sandra Summerova Ludmila Vodickova Pavel Vodicka Veronika Vymetalkova 《International journal of molecular sciences》2022,23(14)
A colorectal adenoma, an aberrantly growing tissue, arises from the intestinal epithelium and is considered as precursor of colorectal cancer (CRC). In this study, we investigated structural and numerical chromosomal aberrations in adenomas, hypothesizing that chromosomal instability (CIN) occurs early in adenomas. We applied array comparative genomic hybridization (aCGH) to fresh frozen colorectal adenomas and their adjacent mucosa from 16 patients who underwent colonoscopy examination. In our study, histologically similar colorectal adenomas showed wide variability in chromosomal instability. Based on the obtained results, we further stratified patients into four distinct groups. The first group showed the gain of MALAT1 and TALAM1, long non-coding RNAs (lncRNAs). The second group involved patients with numerous microdeletions. The third group consisted of patients with a disrupted karyotype. The fourth group of patients did not show any CIN in adenomas. Overall, we identified frequent losses in genes, such as TSC2, COL1A1, NOTCH1, MIR4673, and GNAS, and gene gain containing MALAT1 and TALAM1. Since long non-coding RNA MALAT1 is associated with cancer cell metastasis and migration, its gene amplification represents an important event for adenoma development. 相似文献