全文获取类型
收费全文 | 1656篇 |
免费 | 96篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 754篇 |
金属工艺 | 13篇 |
机械仪表 | 38篇 |
建筑科学 | 53篇 |
能源动力 | 47篇 |
轻工业 | 283篇 |
水利工程 | 13篇 |
石油天然气 | 3篇 |
无线电 | 47篇 |
一般工业技术 | 192篇 |
冶金工业 | 64篇 |
原子能技术 | 8篇 |
自动化技术 | 232篇 |
出版年
2024年 | 2篇 |
2023年 | 26篇 |
2022年 | 158篇 |
2021年 | 185篇 |
2020年 | 57篇 |
2019年 | 49篇 |
2018年 | 38篇 |
2017年 | 42篇 |
2016年 | 69篇 |
2015年 | 65篇 |
2014年 | 57篇 |
2013年 | 125篇 |
2012年 | 92篇 |
2011年 | 123篇 |
2010年 | 75篇 |
2009年 | 76篇 |
2008年 | 103篇 |
2007年 | 64篇 |
2006年 | 33篇 |
2005年 | 49篇 |
2004年 | 34篇 |
2003年 | 36篇 |
2002年 | 30篇 |
2001年 | 15篇 |
2000年 | 15篇 |
1999年 | 19篇 |
1998年 | 20篇 |
1997年 | 14篇 |
1996年 | 12篇 |
1995年 | 10篇 |
1994年 | 11篇 |
1993年 | 8篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有1752条查询结果,搜索用时 15 毫秒
91.
María del Pilar Monge Alejandra Paola Magnoli Maria Virginia Bergesio Nestor Tancredi Carina E. Magnoli 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2016,33(6):1043-1052
Aflatoxin B1 (AFB1) and fumonisin B1 (FB1) are mycotoxins that often co-occur in feedstuffs. The ingestion of AFB1 causes aflatoxicosis in humans and animals. Sodium bentonite (NaB), a cheap non-nutritive unselective sequestering agent incorporated in animal diets, can effectively prevent aflatoxicosis. Fumonisins are responsible for equine leukoencephalomalacia and porcine pulmonary oedema, and often have subclinical toxic effects in poultries. Fumonisin B1 and aflatoxin B1 are both strongly adsorbed in vitro on sodium bentonite. Co-adsorption studies, carried out with a weight ratio of FB1 to AFB1 that mimics the natural occurrence (200:1), showed that FB1 greatly decreases the in vitro ability of NaB to adsorb AFB1. The ability of two activated carbons to adsorb FB1 was also investigated. Both carbons showed high affinity for FB1. A complex behaviour of the FB1 adsorption isotherms with pH was observed. In vitro results suggest that under natural contamination levels of AFB1 and FB1, a mixture of activated carbon and sodium bentonite might be potentially useful for prevention of sub-acute aflatoxicosis. 相似文献
92.
Josefina Pérez-Arantegui Judit Molera Angel Larrea Trinitat Pradell Marius Vendrell-Saz Ilaria Borgia Brunetto G. Brunetti Franco Cariati Paola Fermo Marcello Mellini Antonio Sgamellotti Cecilia Viti 《Journal of the American Ceramic Society》2001,84(2):442-46
Luster is a decorative metallic film that was applied on the surface of medieval glazed pottery. It can be obtained via the low-temperature (∼650°C), controlled reduction of copper and silver compounds. In this paper, we show that luster is a thin layered film (200–500 nm thick) that contains metallic spherical nanocrystals dispersed in a silicon-rich matrix and has a metal-free outermost glassy layer that is 10–20 nm thick. Silver nanocrystals seem to be separated from those of copper, forming aggregates 5–100 μm in diameter. This composite structure exhibits optical properties that are dependent on both the particle size and the matrix. Luster is indeed the first reproducible nanostructured thin metallic film that was made by humans. 相似文献
93.
The influence of saliva on aroma release from white and red wines was studied in a model mouth system. Aroma compounds were analysed in the dynamic headspace of wines by solid phase micro extraction/gas chromatography with flame ionization detection. Volatile compounds were identified by solid phase micro extraction/gas chromatography-mass spectrometry, resulting in a total of 43 compounds in white wine and 41 in red wine. The results showed a greater influence of saliva on aroma release in white wine than red wine. In white wine treated with human saliva, esters and fusel alcohols, responsible for fruity and fusel oil odours, were reduced of 32–80%; by contrast, the concentration of 2-phenylethanol and furfural, responsible for rose and toasted almond notes, increased by 27% and by 155%, respectively. In red wine, treated with human saliva, only a few esters decrease, with a reduction of 22–51% due to protein-binding ability of polyphenols that are able to inhibit the activity of the saliva. C-13 norisoprenoids, vitispirane (eucalyptol) and TDN (kerosene), decreased both in white and red wine, showing a comparable variation while, for β-damascenone, the variation was insignificant. 相似文献
94.
Almerinda Di Benedetto Paola Russo Roberto Sanchirico Valeria Di Sarli 《American Institute of Chemical Engineers》2015,61(5):1572-1580
A Computational Fluid Dynamics (CFD) model was developed with the aim at simulating the turbulent flow field and associated dust dispersion in an agitated spherical explosion vessel. Simulations were performed in the presence of two counter‐rotating fans and also after having switched‐off the fans. Numerical results have shown that the dust mainly accumulates at the center of the sphere in the space left by the four vortices formed. After the switch‐off of the fans, the dust particles start filling the empty volumes inside the sphere, reaching a quite uniform distribution (with concentration equal to the nominal value) and simultaneously ensuring a controlled value of turbulent kinetic energy. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1572–1580, 2015 相似文献
95.
Massimo Lorusso Alberta Aversa Diego Manfredi Flaviana Calignano Elisa Paola Ambrosio Daniele Ugues Matteo Pavese 《Journal of Materials Engineering and Performance》2016,25(8):3152-3160
Direct metal laser sintering (DMLS) is an additive manufacturing technique for the production of parts with complex geometry and it is especially appropriate for structural applications in aircraft and automotive industries. Aluminum-based metal matrix composites (MMCs) are promising materials for these applications because they are lightweight, ductile, and have a good strength-to-weight ratio This paper presents an investigation of microstructure, hardness, and tribological properties of AlSi10Mg alloy and AlSi10Mg alloy/TiB2 composites prepared by DMLS. MMCs were realized with two different compositions: 10% wt. of microsize TiB2, 1% wt. of nanosize TiB2. Wear tests were performed using a pin-on-disk apparatus on the prepared samples. Performances of AlSi10Mg samples manufactured by DMLS were also compared with the results obtained on AlSi10Mg alloy samples made by casting. It was found that the composites displayed a lower coefficient of friction (COF), but in the case of microsize TiB2 reinforcement the wear rate was higher than with nanosize reinforcements and aluminum alloy without reinforcement. AlSi10Mg obtained by DMLS showed a higher COF than AlSi10Mg obtained by casting, but the wear rate was higher in the latter case. 相似文献
96.
Paola Savoia Giovanni Cavaliere Elisa Zavattaro Federica Veronese Paolo Fava 《International journal of molecular sciences》2016,17(8)
Kidney transplant recipients frequently suffer from skin infections and malignancies, possibly due to the effects of long-term immunosuppressive therapy. While the relationships between immunosuppression and these pathological conditions have been widely investigated, little is known about the relative incidence and characteristics of inflammatory skin diseases in this type of patient. In this study, we analyze the incidence of a number of inflammatory cutaneous diseases in a cohort of patients who underwent kidney transplantation. Although our study shows a relatively low incidence of these pathologies in transplanted patients—in agreement with the general action of immunosuppressant therapies in reducing inflammation—we scored a different efficacy of the various immunosuppressive regimens on inflammatory and autoimmune skin diseases. This information can be key for designing immunosuppressive regimens and devising accurate follow-up protocols. 相似文献
97.
Marta Anna Szychlinska Francesca Maria Trovato Michelino Di Rosa Lucia Malaguarnera Lidia Puzzo Rosy Leonardi Paola Castrogiovanni Giuseppe Musumeci 《International journal of molecular sciences》2016,17(3)
Osteoarthritis is the most common human arthritis characterized by degeneration of articular cartilage. Several studies reported that levels of human cartilage glycoprotein chitinase 3-like-1 (CHI3L1) are known as a potential marker for the activation of chondrocytes and the progression of Osteoarthritis (OA), whereas lubricin appears to be chondroprotective. The aim of this study was to investigate the co-expression and co-localization of CHI3L1 and lubricin in normal and osteoarthritic rat articular cartilage to correlate their modified expression to a specific grade of OA. Samples of normal and osteoarthritic rat articular cartilage were analyzed by the Kellgren–Lawrence OA severity scores, the Kraus’ modified Mankin score and the Histopathology Osteoarthritis Research Society International (OARSI) system for histomorphometric evaluations, and through CHI3L1 and lubricin gene expression, immunohistochemistry and double immuno-staining analysis. The immunoexpression and the mRNA levels of lubricin increased in normal cartilage and decreased in OA cartilage (normal vs. OA, p < 0.01). By contrast, the immunoexpression and the mRNA levels of CHI3L1 increased in OA cartilage and decreased in normal cartilage (normal vs. OA, p < 0.01). Our findings are consistent with reports suggesting that these two glycoproteins are functionally associated with the development of OA and in particular with grade 2/3 of OA, suggesting that in the future they could be helpful to stage the severity and progression of the disease. 相似文献
98.
A wave of recent cross-national research has pointed to the positive consequences for countries with high levels of “quality of government” (QoG), broadly defined, such as corruption, impartiality, and quality of public services. Yet the question of how QoG varies at the sub-national level is still widely overlooked, in particular with measures that are available over time. To address it, we present the third round of data from the regional European Quality of Government Index (EQI) survey corruption (D73), Europe (N44) governance (H11); sub-national (R50), time series (C22), collected in 2017 and built upon the opinions of 78,000 respondents in 193 regions from 21 European countries. The data provides several contributions to the literature. First, while the majority of QoG-type indices rely on expert assessments, the EQI relies on the assessments of citizens, who are the on-the-ground consumers of public services. Second, the data begins to show trends on QoG variation over time, as well as across European regions. Consequently, this data is the most comprehensive sub-national data to date; mapping of QoG within and across EU countries over the past decade. Building on previous rounds of data collected in 2010 and 2013, the 2017 EQI, which is published free for scholarly use, builds on both perceptions and experiences of citizens in public service areas such as health care, education, and law enforcement. This paper presents the results of the latest survey, improved with respect to the previous ones, discussion of trends across space and over time, as well as interesting avenues for future research that we detect across European regions. 相似文献
99.
Xavier Kurten (?–1840) was a Prussian landscape gardener who worked for the Savoy family in the Piedmont region of Italy in the first half of the nineteenth century. He designed or redesigned all royal parks, creating a specific style based on the English naturalistic garden approach. This research was performed with the aim of investigating the development of the English landscape garden in Italy. Historical documents relating to Kurten’s biography and his work in Piedmont, including plans, were collected and analysed. We analyse and discuss the features that characterised his work: the relationship between the landscape—garden—house, the path system, the use of water, the vegetation, and the garden as a productive landscape. Kurten’s style is compared with the projects of William Kent and Lancelot ‘Capability’ Brown. 相似文献
100.
Roberta Gentilini Sabrina Bozzini Fabiola Munarin Paola Petrini Livia Visai Maria Cristina Tanzi 《应用聚合物科学杂志》2014,131(2)
Extraction, purification, and gel preparation of Aloe Vera pectin and the evaluation of the biocompatibility of the pectin gels were studied, considering as end use as implantable materials for regenerative medicine. A. Vera was chosen as source of pectin, as this pectin was described to possess high molecular weight and a low degree of esterification. As the properties of pectins are strictly dependent upon the extraction methods in combination with the natural source, the extraction method was modified in order to optimize the yield of the final product, its purity, the duration of the process and the selection of non‐toxic chemical reagents. Changing the experimental conditions resulted in four different extraction processes and products with different physical and chemical characteristics. The optimal extraction resulted to be the process: with enzimatic deactivation by microwave and the use of sodium citrate as chelating agent the molecular weight of the pectin extracted was estimated to be 118 kDa and the 2.93% esterification degree. Cytocompatibility of pectin gels, prepared by ionotropic gelation, showing an improved cell adhesion if compared to commercial pectin. The results suggest that the extracted A. Vera pectins possess interesting properties to be exploited for the production of mechanically stable gels by ionotropic gelation and high rhamnose content matrices for application in regenerative medicine. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39760. 相似文献