全文获取类型
收费全文 | 295篇 |
免费 | 23篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 141篇 |
金属工艺 | 6篇 |
机械仪表 | 9篇 |
建筑科学 | 13篇 |
矿业工程 | 2篇 |
能源动力 | 4篇 |
轻工业 | 49篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 3篇 |
一般工业技术 | 55篇 |
冶金工业 | 10篇 |
自动化技术 | 22篇 |
出版年
2023年 | 5篇 |
2022年 | 24篇 |
2021年 | 29篇 |
2020年 | 13篇 |
2019年 | 9篇 |
2018年 | 10篇 |
2017年 | 21篇 |
2016年 | 14篇 |
2015年 | 12篇 |
2014年 | 9篇 |
2013年 | 28篇 |
2012年 | 18篇 |
2011年 | 28篇 |
2010年 | 16篇 |
2009年 | 18篇 |
2008年 | 19篇 |
2007年 | 13篇 |
2006年 | 5篇 |
2005年 | 4篇 |
2004年 | 4篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 5篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1986年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有318条查询结果,搜索用时 15 毫秒
301.
Monika Hud
ov Slvka Hamuakov Eva Konkoov Rastislav Jendelovský Jana Vargov Juraj evc Peter Fedoro
ko Ondrej Soukup Jana Jano
kov Veronika Ihnatova Tom Ku
era Petr Bzonek Nikola Novakova Daniel Jun Lucie Junova Jan Korbe
ný Kamil Ku
a Mria Kourkov 《International journal of molecular sciences》2021,22(8)
A series of novel C4-C7-tethered biscoumarin derivatives (12a–e) linked through piperazine moiety was designed, synthesized, and evaluated biological/therapeutic potential. Biscoumarin 12d was found to be the most effective inhibitor of both acetylcholinesterase (AChE, IC50 = 6.30 µM) and butyrylcholinesterase (BChE, IC50 = 49 µM). Detailed molecular modelling studies compared the accommodation of ensaculin (well-established coumarin derivative tested in phase I of clinical trials) and 12d in the human recombinant AChE (hAChE) active site. The ability of novel compounds to cross the blood–brain barrier (BBB) was predicted with a positive outcome for compound 12e. The antiproliferative effects of newly synthesized biscoumarin derivatives were tested in vitro on human lung carcinoma cell line (A549) and normal colon fibroblast cell line (CCD-18Co). The effect of derivatives on cell proliferation was evaluated by MTT assay, quantification of cell numbers and viability, colony-forming assay, analysis of cell cycle distribution and mitotic activity. Intracellular localization of used derivatives in A549 cells was confirmed by confocal microscopy. Derivatives 12d and 12e showed significant antiproliferative activity in A549 cancer cells without a significant effect on normal CCD-18Co cells. The inhibition of hAChE/human recombinant BChE (hBChE), the antiproliferative activity on cancer cells, and the ability to cross the BBB suggest the high potential of biscoumarin derivatives. Beside the treatment of cancer, 12e might be applicable against disorders such as schizophrenia, and 12d could serve future development as therapeutic agents in the prevention and/or treatment of Alzheimer’s disease. 相似文献
302.
Peng HT Mok M Martineau L Shek PN 《Journal of materials science. Materials in medicine》2007,18(6):1025-1035
This study was conducted to understand the effects of aging methacrylated gelatin solutions on the properties of gelatin-HydroThaneTM Interpenetrating Polymer Network (IPN) films. The latter were prepared from methacrylated gelatin solutions that were either
freshly made or stored at different concentrations and temperatures for various periods. The morphology, swelling stability
and mechanical properties of the IPNs were then accordingly characterized. The IPNs prepared with aged solutions showed a
reduced phase separation; changed from a network-like structure to a continuous phase structure; and demonstrated higher swelling
stabilities and higher elasticity under optimal aging conditions, compared to the IPN prepared with a fresh methacrylated
gelatin solution. An increase in viscosity and a change in phase transition of aged methacrylated gelatin solutions were also
observed, presumably due to the physical structuring of methacrylated gelatin chains (e.g., by the formation of a helix structure),
thus altering the resulting IPN characteristics. A better understanding of the effects of aging methacrylated gelatin solution
on the formation and properties of gelatin-HydroThaneTM IPNs should enable us to further develop our composite biomaterials for different dressing applications. 相似文献
303.
The electrospinning method was used to fabricate nanostructures of Nafion‐poly(vinyl alcohol) (PVA) and Nafion‐poly(ethylene oxide) (PEO). Depending on the ratio between the two polymers, nanospheres and/or nanofibers could be obtained in a reproducible manner. The Nafion‐PVA mats were found to be more conductive than the Nafion‐PEO ones, possibly because of their better mechanical properties when swollen by water. The fiber morphology was always found to be more conductive than the sphere morphology. However, all electrospun mats presented ionic conductivities slightly lower than extruded Nafion 115 or Nafion‐PVA cast films.
304.
Monitoring the early-age hydration of self-compacting concrete using ultrasonic p-wave transmission and isothermal calorimetry 总被引:1,自引:0,他引:1
Bram Desmet Kelly Chrysanthe Atitung Miguel Angel Abril Sanchez John Vantomme Dimitri Feys Nicolas Robeyst Katrien Audenaert Geert De Schutter Veerle Boel Gert Heirman Özlem Cizer Lucie Vandewalle Dionys Van Gemert 《Materials and Structures》2011,44(8):1537-1558
The early-age hydration (≤48 h) of a series of self-compacting concretes and corresponding mortars and one traditionally vibrated concrete and mortar is monitored in a continuous way using ultrasonic testing and isothermal calorimetry. The mixtures differ in type of mineral addition, superplasticizer, cement, cement-to-powder ratio and water-to-powder ratio. The influence of these different mixture compositions on the kinetics of the hydration during the first days of the hydration is characterized by the heat production rate q and the evolution of the p-wave velocity, which is a consequence of the microstructural changes. The variations in the acceleration caused by mineral additions and the deceleration caused by superplasticizers lead to a significantly different behavior. Separating the impact of each of the affecting factors is not always possible due to their combined actions. The nature of the acceleration due to limestone additions and the deceleration caused by polycarboxylate ether superplasticizers can be distinguished clearly, but cannot be quantified. The correlation between the ultrasonic and isothermal calorimetric results is investigated based on parameters related to the start and the end of the setting and reveals the meaningfulness of these parameters when assessing the hydration of self-compacting mixtures with continuous ultrasonic techniques. 相似文献
305.
Effects of the Surface Densities of Glycoclusters on the Determination of Their IC50 and Kd Value Determination by Using a Microarray 下载免费PDF全文
Lucie Dupin Francesca Zuttion Dr. Thomas Géhin Albert Meyer Prof. Dr. Magali Phaner‐Goutorbe Dr. Jean‐Jacques Vasseur Dr. Eliane Souteyrand Dr. François Morvan Dr. Yann Chevolot 《Chembiochem : a European journal of chemical biology》2015,16(16):2329-2336
Pseudomonas aeruginosa (PA) is an opportunistic bacterium involved in 10–30 % of nosocomial diseases. It causes severe lung injury to cystic fibrosis patients, often leading to patient death. PA strains are multidrug resistant, thus making the design of new therapeutics a challenge for public health. One promising therapeutic option is to design glycoclusters that target the virulence factor of PA. LecA is a galactose‐specific lectin that might be involved in adhesion and biofilm formation by PA. The DNA‐directed immobilization (DDI) microarray is a powerful tool for screening and understanding of structure–activity relationships between glycoclusters and lectins. High‐throughput and multiplexed analysis of lectin–glycocluster interactions on a DDI microarray allows measurement of IC50 and dissociation constant (Kd) values with minute amounts of material. In order to study the robustness of the DDI microarray in determination of IC50 and Kd values, the impact of glycocluster surface density was investigated. The data obtained show that measured IC50 values were influenced by glycocluster surface density: as the density of glycoclusters increases, the measured IC50 values increase too. In contrast, the measured Kd values were not affected by glycocluster surface density, provided that the experimental conditions allow interaction between glycocluster and lectin at single‐molecule level (no surface cluster effect). 相似文献
306.
Novák M Mitchell MJ Jacková I Buzek F Schweigstillová J Erbanová L Prikryl R Fottová D 《Environmental science & technology》2007,41(3):703-709
Sulfate aerosols are harmful as respirable particles. They also play a role as cloud condensation nuclei and have radiative effects on global climate. A combination of delta18O-SO4 data with catchment sulfur mass balances was used to constrain processes affecting S cycling in the atmosphere and spruce forests of the Czech Republic. Extremely high S fluxes via spruce throughfall and runoff were measured at Jezeri (49 and 80 kg S ha(-1) yr(-1), respectively). The second catchment, Na Lizu, was 10 times less polluted. In both catchments, delta18O-SO4 decreased in the following order: open-area precipitation > throughfall > runoff. The delta18O-SO4 values of throughfall exhibited a seasonal pattern at both sites, with maxima in summer and minima in winter. This seasonal pattern paralleled delta18O-H2O values, which were offset by -18 per thousand. Sulfate in throughfall was predominantly formed by heterogeneous (aqueous) oxidation of SO2. Wet-deposited sulfate in an open area did not show systematic delta18O-SO4 trends, suggesting formation by homogeneous (gaseous) oxidation and/or transport from large distances. The percentage of incoming S that is organically cycled in soil was similar under the high and the low pollution. High-temperature 18O-rich sulfate was not detected, which contrasts with North American industrial sites. 相似文献
307.
The aim of this work was to assess the FSH-stimulated expression of epidermal growth factor (EGF)-like peptides in cultured cumulus-oocyte complexes (COCs) and to find out the effect of the peptides on cumulus expansion, oocyte maturation, and acquisition of developmental competence in vitro. FSH promptly stimulated expression of amphiregulin (AREG) and epiregulin (EREG), but not betacellulin (BTC) in the cultured COCs. Expression of AREG and EREG reached maximum at 2 or 4 h after FSH addition respectively. FSH also significantly stimulated expression of expansion-related genes (PTGS2, TNFAIP6, and HAS2) in the COCs at 4 and 8 h of culture, with a significant decrease at 20 h of culture. Both AREG and EREG also increased expression of the expansion-related genes; however, the relative abundance of mRNA for each gene was much lower than in the FSH-stimulated COCs. In contrast to FSH, AREG and EREG neither stimulated expression of CYP11A1 in the COCs nor an increase in progesterone production by cumulus cells. AREG and EREG stimulated maturation of oocytes and expansion of cumulus cells, although the percentage of oocytes that had reached metaphase II was significantly lower when compared to FSH-induced maturation. Nevertheless, significantly more oocytes stimulated with AREG and/or EREG developed to blastocyst stage after parthenogenetic activation when compared to oocytes stimulated with FSH alone or combinations of FSH/LH or pregnant mares serum gonadotrophin/human chorionic gonadotrophin. We conclude that EGF-like peptides do not mimic all effects of FSH on the cultured COCs; nevertheless, they yield oocytes with superior developmental competence. 相似文献
308.
309.
Rémy Boulesteix Alexandre Maître Lucie Chrétien Yoël Rabinovitch Christian Sallé 《Journal of the American Ceramic Society》2013,96(6):1724-1731
Controlling residual amount of defects in transparent ceramics is a major challenge for laser applications. This study was focused on microstructural evolution of Nd:YAG ceramics during their reactive solid‐state sintering which was correlated to their optical transmittance. From microstructural observations, the microstructural maps and grain size‐density and grain size‐pore size sintering trajectories of Nd:YAG ceramics were established as a function of silica content. For densities higher than 99.7%, the occurrence of intragranular porosity was correlated to a critical pore radius of 0.16 μm. Silica appears to favor the formation of intragranular porosity which was attributed to the increasing of the grain growth rate compared with the densification one. An analytical model was established by coupling the analytical laws derived from sintering trajectories and the classical theory of light diffusion, allowing to correlate the microstructural features of transparent Nd:YAG ceramics to their optical properties. 相似文献
310.
Lucie Zarybnicka Radka Bacovska Vladimir Spacek Jozef Rychly Miroslav Vecera Milan Alberti 《Polymer-Plastics Technology and Engineering》2017,56(2):153-160
Epoxy resins can exhibit some excellent properties. The basic principle of curing epoxy resins with a curing agent containing multiple amino groups is the crosslinking reaction between active hydrogen atoms from the curing agent and the oxirane groups in the epoxy resin structure. This study deals with the synthesis of derivative of hexachloro-cyclo-triphosphazene (HCCTP) using curing of epoxy resins. The study of our interest is nucleophilic substitution of HCCTP using N-[3-(trimethoxysilyl)propyl]ethylene diamine. The prepared derivative offers two potential advantages over conventional curing systems, namely improving properties during burning. 相似文献