全文获取类型
收费全文 | 5960篇 |
免费 | 576篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 29篇 |
综合类 | 2篇 |
化学工业 | 1582篇 |
金属工艺 | 53篇 |
机械仪表 | 104篇 |
建筑科学 | 212篇 |
矿业工程 | 9篇 |
能源动力 | 146篇 |
轻工业 | 1868篇 |
水利工程 | 55篇 |
石油天然气 | 34篇 |
无线电 | 301篇 |
一般工业技术 | 949篇 |
冶金工业 | 323篇 |
原子能技术 | 13篇 |
自动化技术 | 861篇 |
出版年
2024年 | 20篇 |
2023年 | 73篇 |
2022年 | 184篇 |
2021年 | 218篇 |
2020年 | 187篇 |
2019年 | 226篇 |
2018年 | 341篇 |
2017年 | 297篇 |
2016年 | 336篇 |
2015年 | 296篇 |
2014年 | 340篇 |
2013年 | 592篇 |
2012年 | 484篇 |
2011年 | 518篇 |
2010年 | 334篇 |
2009年 | 267篇 |
2008年 | 262篇 |
2007年 | 286篇 |
2006年 | 189篇 |
2005年 | 168篇 |
2004年 | 143篇 |
2003年 | 138篇 |
2002年 | 117篇 |
2001年 | 44篇 |
2000年 | 34篇 |
1999年 | 43篇 |
1998年 | 84篇 |
1997年 | 76篇 |
1996年 | 40篇 |
1995年 | 42篇 |
1994年 | 28篇 |
1993年 | 21篇 |
1992年 | 10篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 9篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1982年 | 3篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1976年 | 10篇 |
1974年 | 8篇 |
1971年 | 2篇 |
1970年 | 2篇 |
排序方式: 共有6541条查询结果,搜索用时 15 毫秒
1.
2.
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
3.
4.
María P. Albano Liliana B. Garrido 《Journal of Materials Synthesis and Processing》2002,10(4):211-218
Si3N4powders coated with 6 wt% Y2O3and 4 wt% Al2O3were prepared by coprecipitation. The resulting powders were dispersed in water at different pH values and with addition of various amounts of ammonium polyacrylate (NH4PA) to produce 32 vol% slips. The influence of the amount of NH4PA solution added and pH on the rheological properties of 32 vol% coated Si3N4slips were studied. In addition, the sintered density of cast samples was determined and related to the degree of slip dispersion. The adsorption of the NH4PA on the coated particle surface was rather high and the surface became saturated near 0.86 mg/m2at pH 9.2. High NH4PA concentrations (1.7–3 wt%) were necessary to obtain well dispersed 32 vol% coated Si3N4slips at pH 9.2. The best stabilization was obtained with the addition of 2.3 wt% NH4PA; in this condition, the viscosity reached a minimum value of 35 mPa.s at 100 s–1. The slip viscosity increased with increasing pH from 9.2 to 10.2. Slips with low viscosities gave a more dense packing of cast samples and consequently higher sintered density values. 相似文献
5.
Vanesa Rodríguez-Amor Juan P. Fernández-Blázquez Antonio Bello Ernesto Pérez María L. Cerrada 《Polymer Bulletin》2008,60(1):89-96
Summary The effect of molecular weight on the uniaxial orientation process has been analyzed in two samples of thermotropic poly(diethylene
glycol p,p′-bibenzoate), evaluating the influence of that parameter on the type of orientation obtained. Several strain rates and deformation
temperatures have been tested in order to map out the conditions for obtaining the two different kinds of orientation. The
results show that in the lower molecular weight PDEB sample (Mw=31200) it is rather easy to get exclusively perpendicular “anomalous” orientation, with the molecular axes aligned transversely
to the stretching direction. However, it is extremely difficult to obtain 100% parallel “normal” orientation. On the contrary,
either type of orientation or a mixture of them can be easily developed for the higher molecular weight PDEB sample (Mw=102900). 相似文献
6.
M Isabel Sánchez de Rojas Julián Rivera Moisés Frías Félix Marín 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(3):209-217
Copper slag is a by‐product generated during smelting to extract copper metal from the ore. The copper slag obtained may exhibit pozzolanic activity and may therefore be used in the manufacture of addition‐containing cements. In this paper the effect of the incorporation of the copper slag in cement is measured. Blends of copper slag with Portland cement generally possess properties equivalent to Portland cement containing fly ash, but very different to the silica fume incorporation. Copper slag and fly ash reduce the heat of hydration more effectively than silica fume in mortars. The replacement of 30% cement by copper slag reduces the flexural and compressive strength in a similar way to fly ash; however, after 28 days, the reduction is less than the percentage of substitution. Hydrated calcium aluminate phases were analysed using scanning electron microscopy (SEM) and X‐ray diffraction (XRD) techniques. The pozzolanic activity of copper slag is similar to that of fly ash and higher than silica fume. In the presence of low water/cement ratios, certain pozzolanic materials produce a very compact cement paste that limits the space available for hydration products, a determining factor in the formation of hydrated calcium aluminates. SEM was found to be a useful analytical technique when aluminates are formed and can be clearly detected by XRD. Copyright © 2008 Society of Chemical Industry 相似文献
7.
M. Mar López-González 《Polymer》2005,46(12):4322-4329
This work reports the experimental isotherms describing the concentration of oxygen and nitrogen in poly(bisphenol A carbonate-co-4,4′-(3,3,5-trimethylcyclohexylidene) diphenol carbonate) vs pressure, at 30 °C. The solubility coefficients are interpreted in terms of the Flory-Huggins theory, obtaining reasonable values for the enthalpic polymer-gas parameter. A new method is outlined to simulate the probabilities of inserting/removing a gas molecule in a host matrix already containing n molecules of gas. The simulated isotherms representing the pressure dependence of the concentration exhibit the same pattern as those experimentally obtained. 相似文献
8.
9.
10.