全文获取类型
收费全文 | 392110篇 |
免费 | 6522篇 |
国内免费 | 1731篇 |
专业分类
电工技术 | 5759篇 |
综合类 | 2857篇 |
化学工业 | 58104篇 |
金属工艺 | 16281篇 |
机械仪表 | 12033篇 |
建筑科学 | 9665篇 |
矿业工程 | 2179篇 |
能源动力 | 8878篇 |
轻工业 | 30729篇 |
水利工程 | 4495篇 |
石油天然气 | 6255篇 |
武器工业 | 47篇 |
无线电 | 44447篇 |
一般工业技术 | 77656篇 |
冶金工业 | 60944篇 |
原子能技术 | 7883篇 |
自动化技术 | 52151篇 |
出版年
2021年 | 3114篇 |
2020年 | 2364篇 |
2019年 | 2778篇 |
2018年 | 18546篇 |
2017年 | 17547篇 |
2016年 | 14648篇 |
2015年 | 4072篇 |
2014年 | 5943篇 |
2013年 | 14692篇 |
2012年 | 12193篇 |
2011年 | 20633篇 |
2010年 | 16930篇 |
2009年 | 15410篇 |
2008年 | 17127篇 |
2007年 | 17859篇 |
2006年 | 9063篇 |
2005年 | 9332篇 |
2004年 | 9124篇 |
2003年 | 8857篇 |
2002年 | 7890篇 |
2001年 | 7308篇 |
2000年 | 7049篇 |
1999年 | 7312篇 |
1998年 | 18649篇 |
1997年 | 13038篇 |
1996年 | 9919篇 |
1995年 | 7419篇 |
1994年 | 6507篇 |
1993年 | 6540篇 |
1992年 | 4582篇 |
1991年 | 4391篇 |
1990年 | 4273篇 |
1989年 | 4232篇 |
1988年 | 3929篇 |
1987年 | 3524篇 |
1986年 | 3529篇 |
1985年 | 3907篇 |
1984年 | 3611篇 |
1983年 | 3324篇 |
1982年 | 3155篇 |
1981年 | 3191篇 |
1980年 | 3157篇 |
1979年 | 2931篇 |
1978年 | 2967篇 |
1977年 | 3300篇 |
1976年 | 4426篇 |
1975年 | 2485篇 |
1974年 | 2439篇 |
1973年 | 2459篇 |
1972年 | 2054篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
82.
Giorgio Benedek Joseph R. Manson Salvador Miret-Artés 《Advanced materials (Deerfield Beach, Fla.)》2020,32(25):2002072
Atom scattering is becoming recognized as a sensitive probe of the electron–phonon interaction parameter λ at metal and metal-overlayer surfaces. Here, the theory is developed, linking λ to the thermal attenuation of atom scattering spectra (in particular, the Debye–Waller factor), to conducting materials of different dimensions, from quasi-1D systems such as W(110):H(1 × 1) and Bi(114), to quasi-2D layered chalcogenides, and high-dimensional surfaces such as quasicrystalline 2ML-Ba(0001)/Cu(001) and d-AlNiCo(00001). Values of λ obtained using He atoms compare favorably with known values for the bulk materials. The corresponding analysis indicates in addition, the number of layers contributing to the electron–phonon interaction, which is measured in an atom surface collision. 相似文献
83.
Akopdzhanyan T. G. Chemagina E. A. Borovinskaya I. P. 《Russian Journal of Non-Ferrous Metals》2020,61(6):686-690
Russian Journal of Non-Ferrous Metals - The synthesis and sintering of the (AlN)x(SiC)1 – x solid solution have been studied under conditions of self-propagating high-temperature synthesis... 相似文献
84.
Madhu H. C. Edachery Vimal Lijesh K. P. Perugu Chandra Shekhar Kailas Satish V. 《Metallurgical and Materials Transactions A》2020,51(8):4086-4099
Metallurgical and Materials Transactions A - Hybrid nanocomposites have potential as wear-resistant materials. However, synthesizing these nanocomposites by conventional molten state methods result... 相似文献
85.
Zavadiuk S.V. Loboda P.I. Soloviova T.O. Trosnikova I.Iu. Karasevska O.P. 《Powder Metallurgy and Metal Ceramics》2020,59(1-2):22-28
Powder Metallurgy and Metal Ceramics - The properties of sintered and heat-treated steels produced from the Catamold 8740 material by powder injection molding were examined. Parts made of the... 相似文献
86.
87.
Esteban Vera Pingitore María Silvina Juárez Tomás Birgitt Wiese 《Drug development and industrial pharmacy》2015,41(6):942-952
Context: The administration of pharmabiotics is a promising alternative to antimicrobial drugs for the treatment and/or prevention of female urogenital infections.Objective: To design pharmabiotic formulations including bioactive ingredients of microbial origin combined with non-microbial substances and then to evaluate the stability of the combinations during freeze-drying and storage.Materials and methods: Different formulations including Lactobacillus gasseri CRL 1263, Lactobacillus salivarius CRL 1328, salivaricin CRL 1328 (a bacteriocin) and non-microbial compounds (lactose, inulin and ascorbic acid) were assayed, and the ingredients were freeze-dried together or separately. The formulations were stored in gelatin capsules at 4?°C for 360?d.Results: The viability of lactobacilli was affected to different extents depending on the strains and on the formulations assayed. L. salivarius and ascorbic acid were successfully combined only after the freeze-drying process. Salivaricin activity was not detected in formulations containing L. gasseri. However, when combined with ascorbic acid, lactose, inulin or L. salivarius, the bacteriocin maintained its activity for 360?d. The selected microorganisms proved to be compatible for their inclusion in multi-strain formulations together with lactose, inulin and ascorbic acid. Salivaricin could be included only in a L. salivarius CRL 1328 single-strain formulation together with non-microbial substances.Conclusions: This study provides new insights into the design of urogenital pharmabiotics combining beneficial lactobacilli, salivaricin CRL 1328 and compounds with different functionalities. 相似文献
88.
89.
90.
Marcela Stoia Cornelia Păcurariu Ciprian Mihali Iosif Mălăescu Cătălin Nicolae Marin Aylin Căpraru 《Ceramics International》2019,45(2):2725-2735
Magnetic MnFe2O4 nanopowders were synthesized by an original solvothermal method in the absence and in the presence of tetra-n-butylammonium bromide (TBAB) and Tween 80 (TW) as surfactants. Manganese ferrite/polyaniline (PANI) hybrid materials were synthesized by in situ polymerization of aniline on the surface of MnFe2O4 using ammonium persulfate as oxidant. The purpose of the study was to investigate the influence of the two surfactants on the properties of the MnFe2O4 powders and of their composites with PANI. The specific surface area, the cumulative surface area of pores and the cumulative volume of pores are influenced by the nature of surfactant in case of MnFe2O4 powders and are higher by comparison to those of the MnFe2O4/PANI hybrid materials. The values of saturation magnetization in case of MnFe2O4 powders are higher than those of the hybrid materials and are not influenced by the surfactant nature. These features revealed that MnFe2O4 powders can be efficiently used as adsorbents for the purification of wastewaters. The values of the electrical conductivity of the composites exhibit a significant increase in comparison to the MnFe2O4 powders and depend on the surfactant nature. The highest value of electrical conductivity was achieved by the composite obtained using Tween 80 as surfactant (σDC = 54.5·10?5S?m?1) which was close to that of PANI (σDC = 61.2·10?5 S?m?1). The fact that the magnetic and electric properties of the synthesized MnFe2O4/PANI composites can be changed by design, demonstrate the high potential of these materials to be used in magneto-electric applications. 相似文献