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排序方式: 共有928条查询结果,搜索用时 296 毫秒
101.
Andréa G. Antonio Renata S. Moraes Daniel Perrone Lucianne C. Maia Kátia Regina N. Santos Natália L.P. Iório Adriana Farah 《Food chemistry》2010
Coffee beverage has been associated with antibacterial activity against Streptococcus mutans, a cariogenic bacterium. This study aimed at identifying natural compounds in coffee that contribute to such activity and investigate the influence of species, roasting and decaffeination on it. Coffee chemical compounds and aqueous extracts of green and roasted regular and decaffeinated Coffea arabica and Coffea canephora beans were tested. MIC, biofilm inhibition and biofilm reduction results were correlated with the concentration of coffee compounds in the extracts. 5-Caffeoylquinic acid, trigonelline and caffeic acid solutions showed bacteriostatic activity (MIC = 0.8 mg/mL). Lighter and regular extracts showed higher inhibitory activity than darker and decaffeinated extracts, with an inverse correlation between bacterial colony-forming units and roasting degree. Only regular C. canephora extracts showed biofilm formation inhibition. The joint effect of chlorogenic acids, trigonelline and caffeine or other compounds removed by decaffeination seems to be one of the causes for coffee antibacterial activity against S. mutans. 相似文献
102.
Michele Espinosa da Cunha Laiza Canielas Krause Maria Silvana Aranda Moraes Candice Schmitt Faccini Rosângela Assis Jacques Suelen Rodrigues Almeida Maria Regina Alves Rodrigues Elina Bastos Caramão 《Fuel Processing Technology》2009
In the present work, the process of biodiesel production in a pilot plant has been studied using beef tallow as raw materials with methanol and potassium hydroxide as catalyst. The biodiesel quality is regulated by Brazilian specifications (Resolution 42) by the National Agency of Petroleum (ANP). The alkaline transesterification of animal fat with methanol produces a biodiesel with high quality and also with a good conversion rate. The process is possible but the economical viability must be improved by recovering methanol and glycerin. The obtained results have been used for industrial scale up of the process. 相似文献
103.
104.
Microbiological water quality along the Danube River: Integrating data from two whole-river surveys and a transnational monitoring network 总被引:1,自引:0,他引:1
Alexander K.T. Kirschner Gerhard G. Kavka Branko Velimirov Robert L. Mach Regina Sommer Andreas H. Farnleitner 《Water research》2009,43(15):3673-3684
The River Danube is with 2780 km the second longest river in Europe. Its catchment area covers 801 500 km2, with approximately 81 million inhabitants in 19 countries. River water for anthropogenic use, transportation and recreation is of major importance in all of these countries. Microbiological contamination from faecal pollution by anthropogenic sources is considered to be a crucial problem throughout the Danube River basin. Thus, detailed knowledge on the extent and the origin of microbial pollution is essential for watershed management. The determination of faecal indicator concentrations along the Danube and its major tributaries during two whole-river surveys and 16 permanent stations allowed for the first time to draw a clear picture of the faecal pollution patterns along the whole longitudinal profile of this important international river. By including a variety of environmental variables in statistical analysis, an integrative picture of faecal pollution in the Danube River basin could be evolved. Four hot spots and six stretches of differing faecal pollution were identified, mainly linked with input from large municipalities. Significant decline of microbiological pollution was observed in the upper and lower Danube stretches over the investigation period. In contrast, a significant increase in the middle part was evident. The planned implementation of new wastewater treatment plants and advanced wastewater treatment measures according to the European Union urban wastewater directive will have a great potential to reduce microbial faecal pollution in the Danube and thus improving water quality. 相似文献
105.
Two polymers of same functional group were used; one with greater chain flexibility, PA 6.6, and the other with two benzene rings in the main chain, PA 6I-6T (aPA), to evaluate how the structure influences on the nanoparticle dispersion homogeneity and on dynamic-mechanical properties. In the aPA nanocomposites, good dispersion and homogeneous distribution were observed for all CNT concentrations. However, PA 6.6 nanocomposites showed agglomerated regions in all formulations. The interfacial energy of the aPA/CNT was five times lower than that of PA6.6/CNT, resulting in greater compatibility in this nanocomposite. An increase of up to 26% was observed with 2.5% of CNT in aPA nanocomposites storage modulus. In the samples with PA 6.6, the increase was at most 5%. Even with greater flexibility of PA 6.6 macromolecules, the π-π interaction between the aPA aromatic rings and CNTs might be the decisive factor for dispersion improvement and positively influence on the dynamic-mechanical properties of these nanocomposites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48195. 相似文献
106.
Arildo José Braz de Oliveira Regina Aparecida Correia Gonçalves Talita Perez Cantuaria Chierrito Marcelo Müller dos Santos Lauro Mera de Souza Philip Albert James Gorin Guilherme Lanzi Sassaki Marcello Iacomini 《Food chemistry》2011
Fructooligosaccharides have been isolated from roots and leaves of Stevia rebaudiana, by hot aqueous extraction, followed by precipitation with ethanol. Their structure has been determined using methylation and NMR analysis, MALDI-TOF, and ESI-MS. Fructooligosaccharides contained almost exclusively (2→1)-linked β-fructofuranosyl, with terminal α-glucopyranosyl and β-fructofuranosyl units. MALDI-TOF and ESI-MS analyses showed the wide range of degree of polymerisation (DP) present in various extracts. From roots and leaves, three different fractions gave profiles of homologous series, with DPs ranging up to 17 with MALDI-TOF and 19 using ESI-MS. These inulin-type fructooligosaccharides were the major component of extracts from S. rebaudiana roots and significant components from the leaves. 相似文献
107.
Eunice Valduga Cátia Regina Martin Schwartz Pihetra Oliveira Tatsch Lídia Tiggemann Marco Di Luccio Helen Treichel 《European Food Research and Technology》2011,232(3):453-462
This study aimed at optimising the cultivation conditions for the production of carotenoids by Sporidiobolus salmonicolor (CBS 2636) in a bioreactor. The maximum content of total carotenoids in the full factorial design 22 was 3131.3 μg/L in synthetic
medium with 80 g/L of glucose, 15 g/L of peptone, 5 g/L of malt extract, aeration of 1.5 vvm, agitation of 180 rpm, initial
pH of 4.0 at 25 °C. In the kinetic study, we could observe that the bioproduction of carotenoids is associated with cell growth
in the exponential phase, and the average specific growth (μ) in bioreactor is 0.046 h−1 with a maximum yield of 0.19 g cells/L h. The maximum yield of carotenoids (60.0 μg/Lh) is observed at 50-h bioproduction.
The conversion factor for total organic carbon (TOC) in cells (YX/SCOT) was 2.97 g/g (0–50 h) and 0.254 g/g (50–100 h), the conversion factor glucose into cells (YX/Sglicose) was 0.168 g/g (0–100 h). The specific production of carotenoids (YP/X) was 390 μg of carotenoids per gram of cells, the conversion factor of carbon in the product (YP/SCOT) was 107.8 μg/g (0–50 h) and 34.4 μg/g (50–100 h), whereas the factor YP/Sglicose was 69.59 μg/g. The agitation and aeration provided better homogeneity in the culture medium, and hence greater availability
of nutrients and oxygen, leading to higher production of carotenoids. 相似文献
108.
Stephan Altmann Jürgen Mut Natalia Wolf Jutta Meißner-Weigl Maximilian Rudert Franz Jakob Marcus Gutmann Tessa Lühmann Jürgen Seibel Regina Ebert 《International journal of molecular sciences》2021,22(6)
Metabolic glycoengineering enables a directed modification of cell surfaces by introducing target molecules to surface proteins displaying new features. Biochemical pathways involving glycans differ in dependence on the cell type; therefore, this technique should be tailored for the best results. We characterized metabolic glycoengineering in telomerase-immortalized human mesenchymal stromal cells (hMSC-TERT) as a model for primary hMSC, to investigate its applicability in TERT-modified cell lines. The metabolic incorporation of N-azidoacetylmannosamine (Ac4ManNAz) and N-alkyneacetylmannosamine (Ac4ManNAl) into the glycocalyx as a first step in the glycoengineering process revealed no adverse effects on cell viability or gene expression, and the in vitro multipotency (osteogenic and adipogenic differentiation potential) was maintained under these adapted culture conditions. In the second step, glycoengineered cells were modified with fluorescent dyes using Cu-mediated click chemistry. In these analyses, the two mannose derivatives showed superior incorporation efficiencies compared to glucose and galactose isomers. In time-dependent experiments, the incorporation of Ac4ManNAz was detectable for up to six days while Ac4ManNAl-derived metabolites were absent after two days. Taken together, these findings demonstrate the successful metabolic glycoengineering of immortalized hMSC resulting in transient cell surface modifications, and thus present a useful model to address different scientific questions regarding glycosylation processes in skeletal precursors. 相似文献
109.
110.
Ktia C. Keine Milton C. Kuga Hernn Coaguila‐Llerena Regina G. Palma‐Dibb Gisele Faria 《Microscopy research and technique》2020,83(4):375-380
The aim was to assess the effects of 1% peracetic acid (PAA) as a single endodontic irrigant on microhardness, roughness, and erosion of root canal dentin, compared with 2.5% sodium hypochlorite (NaOCl) and with 2.5% NaOCl combined with 17% EDTA. Forty human, single‐rooted tooth hemisections were submitted to Knoop microhardness test, before and after the following irrigation protocols: PAA = 1% PAA; NaOCl = 2.5% NaOCl; NaOCl‐EDTA‐NaOCl = 2.5% NaOCl +17% EDTA +2.5% NaOCl; and SS = saline. Another 40 roots were instrumented, irrigated with the same protocols, and sectioned longitudinally. The roughness analysis was performed on the mesial section using a confocal laser scanning microscope, whereas erosion was analyzed on each third of the distal section, using a scanning electron microscope. The data were analyzed using ANOVA and Tukey post‐tests, and Kruskal‐Wallis and Dunn post‐tests (α = .05). The PAA and NaOCl‐EDTA‐NaOCl groups showed no significant differences (p > .05); both promoted reduction in microhardness and increase in roughness, compared with the NaOCl and SS groups (p < .05). NaOCl‐EDTA‐NaOCl promoted higher erosion in the cervical and middle thirds than the other groups (p < .05); there was no difference among PAA, NaOCl, and SS (p > .05). There was also no difference among the groups regarding the apical third (p > .05). PAA used as a single endodontic irrigant caused reduction in root canal dentin microhardness and increase in roughness in a similar way to NaOCl‐EDTA‐NaOCl; however, PAA caused less erosion than NaOCl‐EDTA‐NaOCl. 相似文献