全文获取类型
收费全文 | 496篇 |
免费 | 27篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 7篇 |
化学工业 | 130篇 |
金属工艺 | 14篇 |
机械仪表 | 8篇 |
建筑科学 | 6篇 |
能源动力 | 26篇 |
轻工业 | 35篇 |
石油天然气 | 1篇 |
无线电 | 56篇 |
一般工业技术 | 123篇 |
冶金工业 | 71篇 |
原子能技术 | 7篇 |
自动化技术 | 40篇 |
出版年
2023年 | 3篇 |
2022年 | 15篇 |
2021年 | 13篇 |
2020年 | 5篇 |
2019年 | 12篇 |
2018年 | 19篇 |
2017年 | 16篇 |
2016年 | 19篇 |
2015年 | 11篇 |
2014年 | 18篇 |
2013年 | 27篇 |
2012年 | 20篇 |
2011年 | 15篇 |
2010年 | 31篇 |
2009年 | 19篇 |
2008年 | 25篇 |
2007年 | 13篇 |
2006年 | 11篇 |
2005年 | 20篇 |
2004年 | 9篇 |
2003年 | 9篇 |
2002年 | 13篇 |
2001年 | 5篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 20篇 |
1997年 | 7篇 |
1996年 | 12篇 |
1995年 | 13篇 |
1994年 | 13篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 5篇 |
1985年 | 6篇 |
1984年 | 9篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1978年 | 8篇 |
1977年 | 8篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 3篇 |
排序方式: 共有524条查询结果,搜索用时 15 毫秒
81.
Ashok Mahajan Naazneen Surti Pooja Koladiya 《Drug development and industrial pharmacy》2018,44(3):463-471
The aim of the present study was to improve the dissolution and flow properties of lurasidone hydrochloride (LH) by solid dispersion adsorbate (SDA) technique. Solid dispersions (SDs) of LH were prepared by fusion method using Poloxamer P188. The melt dispersion was adsorbed onto the porous carrier Florite (calcium silicate). A 32 factorial design was employed to quantify the effect of two independent variables, namely ratio of carrier (Poloxamer 188) and LH in SD and ratio of adsorbent (Florite) to SD. SDA granules of LH were studied for flow properties and characterized using differential scanning calorimetry, scanning electron microscopy, and X-ray diffraction. Tablets of optimized composition of SDA granules (equivalent to 20?mg of drug) and plain tablets were prepared by direct compression method. The dissolution studies were carried out in Mcllvaine buffer (pH 3.8) as per USFDA guidelines and characterized for parameters such as percent dissolution efficiency, t50, and Q30. Tablets prepared from SDA granules showed almost four-fold increase in cumulative percentage drug release as compared to tablets prepared from plain LH. The value of dissolution efficiency was enhanced from 49.60% for plain tablets to 94.15% for SDA tablets. SDA granules did not show any change in drug release and X-ray diffraction pattern after storage at 40?°C/75% of RH for 3?months, which confirms that Florite prevented conversion of drug from amorphous form to crystalline form improving physical stability of the amorphous state of LH. 相似文献
82.
B. V. Radhakrishna Bhat Y. R. Mahajan H. Md. Roshan YVRK Prasad 《Metallurgical and Materials Transactions A》1992,23(8):2223-2230
The constitutive flow behavior of a metal matrix composite (MMC) with 2124 aluminum containing 20 vol pct silicon carbide
particulates under hot-working conditions in the temperature range of 300 °C to 550 °C and strain-rate range of 0.001 to 1
s-1 has been studied using hot compression testing. Processing maps depicting the variation of the efficiency of power dissipation
given by [2m/(m + 1)] (wherem is the strain-rate sensitivity of flow stress) with temperature and strain rate have been established for the MMC as well
as for the matrix material. The maps have been interpreted on the basis of the Dynamic Materials Model (DMM). [3] The MMC
exhibited a domain of superplasticity in the temperature range of 450 °C to 550 °C and at strain rates less than 0.1 s-1. At 500 °C and 1 s-1 strain rate, the MMC undergoes dynamic recrystallization (DRX), resulting in a reconstitution of microstructure. In comparison
with the map for the matrix material, the DRX domain occurred at a strain rate higher by three orders of magnitude. At temperatures
lower than 400 °C, the MMC exhibited dynamic recovery, while at 550 °C and 1 s-1, cracking occurred at the prior particle boundaries (representing surfaces of the initial powder particles). The optimum
temperature and strain-rate combination for billet conditioning of the MMC is 500 °C and 1 s-1, while secondary metalworking may be done in the super- plasticity domain. The MMC undergoes microstructural instability
at temperatures lower than 400 °C and strain rates higher than 0.1 s-1. 相似文献
83.
84.
The outcome of a print in production run plays a crucial role in commercial and packaging printing. In the growing packaging industry, colorfulness and saturated prints with high chroma attract the eye of the consumer. The design and layout of a packaging carton comprise of images that consist of halftones in the print process, which demand attractiveness and visibility using bright colors. In this research, an effort has been made to identify and analyze various parameters involved in offset lithography affecting color attributes of prints. This study also focused on the investigation of the best process conditions that would yield optimum color values through multiresponse factors such as chroma and lightness. A general full-factorial Design of Experiments (DOE) approach was used to evaluate the effect of prepress parameters such as screen ruling and dot shape and press parameters such ink viscosity and paper smoothness. These parameters were then optimized using a customized response surface design. From the experiment, it was observed that viscosity of the ink was a significant factor that majorly controls the color attributes. The surface smoothness of the paperboard was one of the factors influencing the improvement of color reproduction. A smoother surface makes even contact during ink transfer in the offset printing machine and hence reflects color with a higher chroma. The optimum parameters were as follows: 15 Pa s ink viscosity, 0.77 μm paper smoothness, and 200 lines per inch (lpi) screen ruling that resulted in increasing chroma (C*) in the middle and shadow tones in the halftones. 相似文献
85.
Understanding the effect of time and temperature on the respiration rate (RR) of fresh-cut produce, towards the design of a suitable modified atmosphere packaging (MAP) system, requires an adequate mathematical model for prediction of RR as a function of both time and temperature. This study investigated the effect of temperature (5, 10, and 15 °C) and storage time (1 to 5 d) on the RR (R(O2) and R(CO2)) of 2 pomegranate cultivars (cv. "Acco" and "Herskawitz") fresh arils. R(O2) and R(CO2) were 3 to 4 folds significantly higher with increased temperature from 5 to 15 °C and were within the range of 2.51 to 7.59 mL/kg h and 2.72 to 9.01 mL/kg h, respectively, for both cultivars. At 15 °C R(CO2) increased significantly from 8.4 to 25.96 mL/kg h from day 1 to 5, respectively, while at 5 °C R(CO2) changed from 2.9 to 2.05 mL/kg h from day 1 to 5. Temperature had the greatest influence on RR and the interaction of time and temperature also significantly affected R(O2) and R(CO2). The respiratory quotient (RQ) estimated by linear regression was 0.98 at 95% significant level. The dependence of RR on temperature and time was accurately described with a combination of an Arrhenius-type and power equation model for and of fresh pomegranate arils. 相似文献
86.
Accurate air temperature measurements made by surface meteorological stations are demanded by climate research programs for various uses. Heating of the temperature sensor due to coupling with the environment can lead to significant errors. Therefore, accurate in situ temperature measurements require shielding the sensor from exposure to direct and reflected solar radiation, while also allowing the sensor to be brought into contact with atmospheric air at the ambient temperature. The difficulty in designing a radiation shield for such a temperature sensor lies in satisfying these two conditions simultaneously. In this paper, we perform a computational fluid dynamics analysis of mechanically aspirated radiation shields (MARS) to study the effect of geometry, wind speed, and interplay of multiple heat transfer processes. Finally, an artificial neural network model is developed to learn the relationship between the temperature error and specified input variables. The model is then used to perform a sensitivity analysis and design optimization. 相似文献
87.
Humidity-Regulating Trays: Moisture Absorption Kinetics and Applications for Fresh Produce Packaging
Guido Rux Pramod V. Mahajan Manfred Linke Astrid Pant Sven Sängerlaub Oluwafemi J. Caleb Martin Geyer 《Food and Bioprocess Technology》2016,9(4):709-716
For packaged fresh produce, inappropriate high relative humidity (RH) levels and condensation of water vapour cause premature spoilage. Humidity-regulating trays were developed to solve this issue. They were made from a thermoformed multilayer structure: polyethylene (outside)/foamed hygroscopic ionomer (active layer) with 0 or 12 wt% NaCl/hygroscopic ionomer (sealing layer, inside). Moisture absorption kinetics of the humidity-regulating trays with 0 and 12 wt% NaCl (T-0 and T-12, respectively) was investigated under different RH conditions (76, 86, 96 and 100 %) at 13 °C for 16 days. Additional trays containing 7 g of distilled water were closed with a high barrier lidding film, and the headspace RH was continuously monitored as a function of time. As control, a polypropylene (control-PP) tray was used. Strawberries and tomatoes were used to test capability of the trays to regulate in-package RH. The amount of water absorbed by the T-0 and T-12 trays was 7.6 and 13.2 g, respectively. Active hygroscopic ionomer layer was effective in water vapour absorption, and the integration of NaCl into this active layer increased the water vapour absorption capacity of the tray. The Weibull model adequately described the moisture sorption kinetics of the individual packaging trays as a function of time. The headspace RH of trays covered with a lidding film was found to be 89.8, 99.6 and 100 % in the T-12, T-0 and control-PP trays, respectively. The T-12 trays containing fresh produce best regulated the in-package RH below 97 % and maintained overall quality, but at the expense of slightly higher product weight loss (2–3 wt% for strawberry, 1 wt% for tomatoes) compared to the control-PP trays (0.3–0.6 wt%). 相似文献
88.
89.
Cotton is dyed very extensively using reactive dyes. Conventionally, reactive dyeing requires voluminous amount of electrolyte and alkali for dyeing of cellulosic fibres like cotton. But the consumption of electrolyte for reactive dyeing of cellulosic textiles increases the pollution load in the textile wastewater. Moreover, there is a possibility of reactive dye hydrolysis in presence of alkali which is detrimental but unavoidable. Therefore, an attempt has been made to eliminate the use of electrolyte and alkali by modifying the cotton substrate with different generations of PAMAM (polyamidoamine) dendrimer using exhaust and continuous method of application. Subsequently, dyeing was carried out by exhaust method without using electrolyte and alkali. The dyed samples were tested for wash fastness, light fastness and rubbing fastness. Colour strength in terms of K/S was also assessed. The results were comparable to those for dyeing obtained by conventional exhaust method. Therefore, the proposed method demonstrates a promising alternative to the conventional dyeing method by completely eliminating electrolyte and alkali. 相似文献
90.
The efficacy of PCR-RFLP analysis of mt 12S rRNA gene in identification of animal species from meat samples of known and unknown origin and adulterated meat samples was evaluated. In PCR, all the samples generated an amplicon of 456 bp. Restriction enzyme digestion of the PCR product with AluI, HhaI, BspTI and ApoI revealed characteristic RFLP patterns. Of the samples of unknown origin few were identified as cattle, few as buffalo and some were admixtures of two, suggesting adulteration. The RFLP pattern of one did not match any of species included in the study, which on sequencing was confirmed as camel meat. Application of this technique on adulterated meat samples could detect both animal species in proportion of 50:50 and 75:25 (except in case of goat+cattle). The technique however could not detect any of the two species when proportion of mixture was 90:10 (except in case of cattle+buffalo). 相似文献