全文获取类型
收费全文 | 103241篇 |
免费 | 1341篇 |
国内免费 | 491篇 |
专业分类
电工技术 | 1473篇 |
综合类 | 2394篇 |
化学工业 | 14508篇 |
金属工艺 | 6021篇 |
机械仪表 | 4616篇 |
建筑科学 | 2477篇 |
矿业工程 | 861篇 |
能源动力 | 1265篇 |
轻工业 | 4055篇 |
水利工程 | 1649篇 |
石油天然气 | 1198篇 |
武器工业 | 11篇 |
无线电 | 11254篇 |
一般工业技术 | 21234篇 |
冶金工业 | 4620篇 |
原子能技术 | 671篇 |
自动化技术 | 26766篇 |
出版年
2023年 | 63篇 |
2022年 | 351篇 |
2021年 | 544篇 |
2020年 | 438篇 |
2019年 | 600篇 |
2018年 | 15501篇 |
2017年 | 14453篇 |
2016年 | 11273篇 |
2015年 | 1380篇 |
2014年 | 1369篇 |
2013年 | 1693篇 |
2012年 | 4435篇 |
2011年 | 10529篇 |
2010年 | 9388篇 |
2009年 | 6848篇 |
2008年 | 7945篇 |
2007年 | 8888篇 |
2006年 | 1051篇 |
2005年 | 1739篇 |
2004年 | 1426篇 |
2003年 | 1296篇 |
2002年 | 675篇 |
2001年 | 231篇 |
2000年 | 628篇 |
1999年 | 396篇 |
1998年 | 381篇 |
1997年 | 370篇 |
1996年 | 90篇 |
1995年 | 22篇 |
1994年 | 26篇 |
1993年 | 21篇 |
1992年 | 26篇 |
1991年 | 34篇 |
1990年 | 22篇 |
1978年 | 21篇 |
1969年 | 46篇 |
1968年 | 58篇 |
1967年 | 43篇 |
1966年 | 44篇 |
1965年 | 46篇 |
1963年 | 30篇 |
1962年 | 23篇 |
1961年 | 26篇 |
1960年 | 40篇 |
1959年 | 44篇 |
1958年 | 45篇 |
1957年 | 37篇 |
1956年 | 41篇 |
1955年 | 67篇 |
1954年 | 72篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Seredin P. V. Radam Ali Obaid Goloshchapov D. L. Len’shin A. S. Buylov N. S. Barkov K. A. Nesterov D. N. Mizerov A. M. Timoshnev S. N. Nikitina E. V. Arsentyev I. N. Sharafidinov Sh. Kukushkin S. A. Kasatkin I. A. 《Semiconductors》2022,56(4):253-258
Semiconductors - Abstract—In our work, we carry out a structural-spectroscopic study of AlGaN/GaN epitaxial layers grown by molecular-beam epitaxy with nitrogen-plasma activation on a hybrid... 相似文献
2.
Fatemeh Norouzi Jobie Mojtaba Ranjbar Akbar Hajizadeh Moghaddam Mahmoud Kiani 《Advanced Powder Technology》2021,32(6):2043-2052
For the first time in this study, Zinc oxide nanoparticles were biosynthesized by the eco-friendly and cost-effective procedure using Amygdalus scoparia stem bark extract then used as antibacterial, antifungal, anticancer, and anti-diabetic agents. The characterization techniques confirmed the biosynthesis, crystalline nature, structure, size, elemental composition of ZnO NPs and bioactive compounds that exist in A. scoparia extract accounting for Zn2+ ion reduction, capping and stabilization of ZnO NPs. The ZnO NPs displayed remarkable inhibitory activity against E. coli, E. aerigenes, S. aureus, P. oryzae, F. thapsinum, and F. semitectum compared to antibiotic standards. The ZnO NPs showed significant inhibitory effects on cancer cell lines, while it had no toxic effect on Vero normal cell line. The ZnO NPs (30 mg/kg)-treated diabetic rats showed significantly higher levels of insulin and lower AST, ALT and blood glucose compared with the STZ induced diabetic group and other treated groups (P < 0.05). The ZnO NPs- and extract-treated rats showed significantly higher levels of IR, GluT2, and GCK expression and lower TNFα expression compared with the STZ induced diabetic rats. Our findings showed that ZnO NPs represented an outstanding performance for biological applications. 相似文献
3.
Golubev N. V. Ignat’eva E. S. Maurus A. A. Ziyatdinova M. Z. Lopatina E. V. Lorenzi R. Paleari A. Sigaev V. N. 《Glass and Ceramics》2021,77(11-12):415-418
Glass and Ceramics - The influence of Al2O3 as an additive and the heat-treatment regime on the luminescence spectra of gallate glass-ceramics was investigated. It is shown that its luminescence... 相似文献
4.
Popov N. N. Presnyakov D. V. Lar’kin V. F. 《Journal of Machinery Manufacture and Reliability》2020,49(3):232-236
Journal of Machinery Manufacture and Reliability - A device based on smart alloys has been designed for use in machine building items, in particular, in nuclear engineering, for preventing... 相似文献
5.
Material encapsulation is a relatively new technique for coating a micro/nanosize particle or droplet with polymeric or inorganic shell. Encapsulation technology has many applications in various fields including drug delivery, cosmetic, agriculture, thermal energy storage, textile, and self-healing polymers. Poly(methyl methacrylate) (PMMA) is widely used as shell material in encapsulation due to its high chemical stability, biocompatibility, nontoxicity, and good mechanical properties. The main approach for micro/nanoencapsulation of materials using PMMA as shell comprises emulsion-based techniques such as emulsion polymerization and solvent evaporation from oil-in-water emulsion. In the present review, we first focus on the encapsulation techniques of liquid materials with PMMA shell by analyzing the effective processing parameters influencing the preparation of PMMA micro/nanocapsules. We then describe the morphology of PMMA capsules in emulsion systems according to thermodynamic relations. The techniques to investigation of mechanical properties of capsule shell and the release mechanisms of core material from PMMA capsules were also investigated. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48039. 相似文献
6.
7.
Mohammad Afshari Amir-Reza Rouhani Isfahani Saeed Hasani Fatemeh Davar Khadijeh Jahanbani Ardakani 《International Journal of Applied Ceramic Technology》2019,16(4):1612-1621
In the present study, spinel structure CoFe2O4 nanoparticles were successfully synthesized by the sol-gel auto-combustion technique. The effect of apple cider vinegar (ACV) addition as an organic biocompatible agent on the size, morphology, and magnetic properties of CoFe2O4 nanoparticles was investigated in detail. The phase evolution, particle size, and lattice parameter changes of the synthesized phase have been estimated by using Rietveld structure refinement analysis of X-ray powder diffraction data. Also, Fourier transform infrared spectra (FT-IR) of the samples verified the presence of two expected bands correspond to tetrahedral and octahedral metal-oxygen complexes within the spinel structure. Furthermore, microstructural observations revealed that ultrafine particles have a semi-spherical morphology. It was shown that the particles size decreased from ~45 to ~17 nm with an increase in the amount of ACV. Magnetic properties were carried out by vibrating sample magnetometer (VSM) at room temperature. Both the saturation magnetization (Ms) and coercivity (Hc) were found to be significantly dependent on the crystallite size and the amount of ACV. 相似文献
8.
Theoretical Foundations of Chemical Engineering - The extraction of nitric and oxalic acids by neutral compounds TBP, DBBP, and TBPO have been studied. The optimal conditions of their separation... 相似文献
9.
Solov’ev V. P. Tsivadze A. Yu. 《Protection of Metals and Physical Chemistry of Surfaces》2015,51(1):1-35
Stability constants and formation enthalpies of supramolecular complexes of crown ethers and their cyclic and acyclic analogues are determined on the basis of experimental data obtained by different physicochemical methods in the terms of a general approach developed and implemented in the ChemEqui software package. The established regularities of variation of stability of complexes are discussed as dependent on the ligand structure, nature of the cation, solvent, and anion. The applicability of the suggested method of determining complexation selectivity is shown for multicomponent equilibria in solutions.
相似文献10.
Pasquale Stano Tereza Pereira de Souza Paolo Carrara Emiliano Altamura Erica D’Aguanno Margherita Caputo 《先进材料力学与结构力学》2015,22(9):748-759
Here we report some recent biophysical issues on the preparation of solute-filled lipid vesicles and their relevance to the construction of “synthetic cells.” First, we introduce the “semi-synthetic minimal cells” as the liposome-based cell-like systems, which contain a minimal number of biomolecules required to display simple and complex biological functions. Next, we focus on recent aspects related to the construction of synthetic cells. Emphasis is given to the interplay between the methods of synthetic cell preparation and the physics of solute encapsulation. We briefly introduce the notion of structural and compositional “diversity” in synthetic cell populations. 相似文献