全文获取类型
收费全文 | 254篇 |
免费 | 18篇 |
专业分类
化学工业 | 129篇 |
金属工艺 | 2篇 |
机械仪表 | 1篇 |
建筑科学 | 6篇 |
矿业工程 | 1篇 |
能源动力 | 4篇 |
轻工业 | 58篇 |
水利工程 | 2篇 |
石油天然气 | 2篇 |
无线电 | 8篇 |
一般工业技术 | 30篇 |
冶金工业 | 6篇 |
原子能技术 | 1篇 |
自动化技术 | 22篇 |
出版年
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 68篇 |
2020年 | 25篇 |
2019年 | 16篇 |
2018年 | 17篇 |
2017年 | 11篇 |
2016年 | 16篇 |
2015年 | 10篇 |
2014年 | 19篇 |
2013年 | 17篇 |
2012年 | 11篇 |
2011年 | 11篇 |
2010年 | 12篇 |
2009年 | 1篇 |
2008年 | 5篇 |
2007年 | 1篇 |
2006年 | 5篇 |
2005年 | 7篇 |
2004年 | 4篇 |
2000年 | 1篇 |
1994年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有272条查询结果,搜索用时 15 毫秒
1.
Pawe Lenartowicz Mateusz Psurski Aleksandra Kotynia Aleksandra Pienina Monika Cuprych Klaudia Poniatowska Justyna Brasu Pawe Kafarski 《International journal of molecular sciences》2021,22(4)
Background: Dehydropeptides are analogs of peptides containing at least one conjugate double bond between α,β-carbon atoms. Its presence provides unique structural properties and reaction centre for chemical modification. In this study, the series of new class of dipeptides containing S-substituted dehydrocysteine with variety of heterocyclic moieties was prepared. The compounds were designed as the building blocks for the construction of artificial metalloenzymes (artzymes). Therefore, the complexing properties of representative compounds were also evaluated. Furthermore, the acknowledged biological activity of natural dehydropeptides was the reason to extend the study for antiproliferative action of against several cancer cell lines. Methods: The synthetic strategy involves glycyl and phenylalanyl-(Z)-β-bromodehydroalanine as a substrate in one pot addition/elimination reaction of thiols. After deprotection of N-terminal amino group the compounds with triazole ring were tested as complexones for copper(II) ions using potentiometric titration and spectroscopic techniques (UV-Vis, CD, EPR). Finally, the antiproliferative activity was evaluated by sulforhodamine B assay. Results and Conclusions: A simple and efficient procedure for preparation of dipeptides containing S-substituded dehydrocysteine was provided. The peptides containing triazole appeared to be strong complexones of copper(II) ions. Some of the peptides exhibited promising antiproliferative activities against number of cancer cell lines, including cell lines resistant to widely used anticancer agent. 相似文献
2.
3.
Grace Lara Chieko Takahashi Miku Nagaya Kunihiko Uemura 《International Journal of Food Science & Technology》2022,57(6):3251-3262
The present study aimed to investigate the influence of radio frequency (RF) heating at 70 and 80 °C, in comparison with the traditional conventional heating. The RF heating technology was applied for maintaining the colour and textural quality as well as inactivating the enzymatic activity of polyphenol oxidase (PPO) and reducing the Escherichia coli growth in packaged fresh-cut peach samples. To evaluate this, 120 g of freshly cut peach fruit was placed in heat-resistant plastic bags, and 50 mL of sugar solution (12°Brix) was added to each bag and vacuum-packed for conventional heating and radio frequency (RF) heating. Our results demonstrated that the RF heating process could reduce the heating time by up to 83% at 70 and 80 °C as compared to conventional heating. Moreover, RF heating at 70 and 80 °C reduced the PPO enzymatic activity, which caused enzymatic browning, up to 85.46% and 93.5%, respectively, as compared to 40.86% reduction only for conventional heating. Furthermore, RF heating completely inhibited E. coli growth. Collectively, we demonstrated that RF heating is an emerging and promising technology for improving the quality of fresh-cut fruits such as peach during various storage conditions. The present study provides relatively novel information on the effectiveness of RF heating in maintaining the quality of fresh-cut peaches. In the future, we would like to investigate the effectiveness of RF heating on other agricultural products. 相似文献
4.
Justyna Zygmuntowicz Paweł Falkowski Marcin Wachowski Konrad Cymerman Paulina Piotrkiewicz Waldemar Kaszuwara 《International Journal of Applied Ceramic Technology》2020,17(4):1731-1741
In the present research, the influence of sintering temperature on the microstructure and properties of Al2O3–Cu–Ni hybrid composites prepared by the Pulse Plasma Sintering (PPS) technique were described. In this research, three temperatures have been selected: 1250°C, 1300°C, and 1350°C. SEM observations were carried out to determine the distribution of the metallic phase in the composite depending on the sintering temperature. The conducted experiments and microscopic observations enabled a better understanding of the phenomena occurring between the ceramic matrix and metallic phase in the obtained materials. The mechanical properties like a hardness and fracture toughness were measured. The technology applied allowed us to obtain ceramic-metal composites with a homogeneous microstructure. It was found that the sintering temperature influences the selected physical and mechanical properties of the composites produced. It was found that samples produced at 1300°C are characterized by the highest relative density and the mechanical properties. 相似文献
5.
Koshi Takenaka Miku Sato Masaya Mitamura Yasunori Yokoyama Naoyuki Katayama Yoshihiko Okamoto 《Journal of the American Ceramic Society》2020,103(4):2757-2763
We used spray-dry method to synthesize fine powder of β-Cu1.8Zn0.2V2O7 showing large negative thermal expansion (NTE) linearly to temperature over a wide temperature range. The NTE of β-Cu1.8Zn0.2V2O7 is produced by microstructures consisting of voids and anisotropic thermal deformation of crystal grains in ceramics. By reducing the size of the microstructures that produce NTE, large NTE equivalent to that of bulk was realized, even for ceramic particles of about 2 μm size. Comparison with particles produced using a conventional method demonstrates that the particle size distribution is narrow and that the particles are nearly spherical. This achievement is expected to pave the way to use of NTE materials in micrometer-scale control of thermal expansion. 相似文献
6.
Maj Justyna Węglewski Witold Bochenek Kamil Rogal Łukasz Woźniacka Stefania Basista Michał 《Metallurgical and Materials Transactions A》2021,52(11):4727-4736
Squeeze casting and powder metallurgy techniques were employed to fabricate AlSi12/Al2O3 composites, which are lightweight structural materials with potential applications in the automotive industry. The impact of the processing route on the material properties was studied. Comparative analyses were conducted for the Vickers hardness, flexural strength, fracture toughness, thermal conductivity, thermal residual stresses, and frictional wear. Our results show that the squeeze cast composite exhibits superior properties to those obtained using powder metallurgy.
相似文献7.
Aleksandra Marciniak Weronika Witak Giuseppina Sabatino Anna Maria Papini Justyna Brasu 《International journal of molecular sciences》2020,21(22)
Somatostatin analogues are useful pharmaceuticals in peptide receptor radionuclide therapy. In previous studies, we analyzed a new bicyclic somatostatin analogue (BCS) in connection with Cu(II) ions. Two characteristic sites were present in the peptide chain: the receptor- and the metal-binding site. We have already shown that this ligand can form very stable imidazole complexes with the metal ion. In this work, our aim was to characterize the intramolecular interaction that occurs in the peptide molecule. Therefore, we analyzed the coordination abilities of two cyclic ligands, i.e., P1 only with the metal binding site and P2 with both sites, but without the disulfide bond. Furthermore, we used magnetic circular dichroism (MCD) spectroscopy to better understand the coordination process. We applied this method to analyze spectra of P1, P2, and BCS, which we have described previously. Additionally, we analyzed the MCD spectra of P3 ligand, which has only the receptor binding site in its structure. We have unequivocally shown that the presence of the Phe-Trp-Lys-Thr motif and the disulfide bond significantly increases the metal binding efficiency. 相似文献
8.
9.
10.
Justyna Popi Agnieszka Gunia-Krzyak Karolina Soczyska Paulina Koczurkiewicz-Adamczyk Kamil Piska Katarzyna Wjcik-Pszczoa Dorota elaszczyk Anna Krupa Pawe mudzki Henryk Marona Elbieta Pkala 《International journal of molecular sciences》2021,22(1)
Excessive UV exposure contributes to several pathological conditions like skin burns, erythema, premature skin aging, photodermatoses, immunosuppression, and skin carcinogenesis. Effective protection from UV radiation may be achieved with the use of sunscreens containing UV filters. Currently used UV filters are characterized by some limitations including systemic absorption, endocrine disruption, skin allergy induction, and cytotoxicity. In the research centers all over the world new molecules are developed to improve the safety, photostability, solubility, and absorption profile of new derivatives. In our study, we designed and synthesized seventeen novel molecules by combining in the structures two chromophores: xanthone and (E)-cinnamoyl moiety. The ultraviolet spectroscopic properties of the tested compounds were confirmed in chloroform solutions. They acted as UVB or UVA/UVB absorbers. The most promising compound 9 (6-methoxy-9-oxo-9H-xanthen-2-yl)methyl (E)-3-(2,4-dimethoxyphenyl)acrylate) absorbed UV radiation in the range 290–369 nm. Its photoprotective activity and functional photostability were further evaluated after wet milling and incorporation in the cream base. This tested formulation with compound 9 possessed very beneficial UV protection parameters (SPFin vitro of 19.69 ± 0.46 and UVA PF of 12.64 ± 0.32) which were similar as broad-spectrum UV filter tris-biphenyl triazine. Additionally, compound 9 was characterized by high values of critical wavelength (381 nm) and UVA/UVB ratio (0.830) thus it was a good candidate for broad-spectrum UV filter and it might protect skin against UVA-induced photoaging. Compound 9 were also shown to be photostable, non-cytotoxic at concentrations up to 50 µM when tested on five cell lines, and non-mutagenic in Ames test. It also possessed no estrogenic activity, according to the results of MCF-7 breast cancer model. Additionally, its favorable lipophilicity (miLogP = 5.62) does not predispose it to penetrate across the skin after topical application. 相似文献