全文获取类型
收费全文 | 2282篇 |
免费 | 169篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 11篇 |
综合类 | 3篇 |
化学工业 | 967篇 |
金属工艺 | 20篇 |
机械仪表 | 42篇 |
建筑科学 | 64篇 |
矿业工程 | 6篇 |
能源动力 | 65篇 |
轻工业 | 472篇 |
水利工程 | 21篇 |
石油天然气 | 5篇 |
无线电 | 113篇 |
一般工业技术 | 309篇 |
冶金工业 | 86篇 |
原子能技术 | 5篇 |
自动化技术 | 263篇 |
出版年
2024年 | 4篇 |
2023年 | 47篇 |
2022年 | 187篇 |
2021年 | 225篇 |
2020年 | 75篇 |
2019年 | 97篇 |
2018年 | 81篇 |
2017年 | 81篇 |
2016年 | 102篇 |
2015年 | 89篇 |
2014年 | 95篇 |
2013年 | 168篇 |
2012年 | 143篇 |
2011年 | 181篇 |
2010年 | 158篇 |
2009年 | 117篇 |
2008年 | 102篇 |
2007年 | 85篇 |
2006年 | 76篇 |
2005年 | 53篇 |
2004年 | 36篇 |
2003年 | 39篇 |
2002年 | 41篇 |
2001年 | 20篇 |
2000年 | 8篇 |
1999年 | 20篇 |
1998年 | 20篇 |
1997年 | 11篇 |
1996年 | 8篇 |
1995年 | 10篇 |
1994年 | 7篇 |
1993年 | 9篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1970年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有2452条查询结果,搜索用时 15 毫秒
121.
Coccoli V Luciani A Orsi S Guarino V Causa F Netti PA 《Journal of materials science. Materials in medicine》2008,19(4):1703-1711
Drug delivery applications using biodegradable polymeric microspheres are becoming an important means of delivering therapeutic
agents. The aim of this work was to modulate the microporosity of poly(ε-caprolactone) (PCL) microcarriers to control protein
loading capability and release profile. PCL microparticles loaded with BSA (bovine serum albumin) have been de novo synthesized
with double emulsion solvent evaporation technique transferred and adapted for different polymer concentrations (1.7 and 3%
w/v) and stabilizer present in the inner aqueous phase (0.05, 0.5 and 1% w/v). SEM (scanning electron microscope) and CLSM
(confocal laser scanning microscope) analysis map the drug distribution in homogeneously distributed cavities inside the microspheres
with dimensions that can be modulated by varying double emulsion process parameters. The inner structure of BSA-loaded microspheres
is greatly affected by the surfactant concentration in the internal aqueous phase, while a slight influence of polymer concentration
in the oil phase was observed. The surfactant concentration mainly determines microspheres morphology, as well as drug release
kinetics, as confirmed by our in-vitro BSA release study. Moreover, the entrapped protein remained unaltered during the protein
encapsulation process, retaining its bio-activity and structure, as shown through a dedicated gel chromatographic analytical
method. 相似文献
122.
Carlota Oleaga Andrea Lavado Anne Riu Sandra Rothemund Carlos A. Carmona‐Moran Keisha Persaud Andrew Yurko Jennifer Lear Narasimhan Sriram Narasimhan Christopher J. Long Frank Sommerhage Lee Richard Bridges Yunqing Cai Candace Martin Mark T. Schnepper Arindom Goswami Reine Note Jessica Langer Silvia Teissier Jos Cotovio James J. Hickman 《Advanced functional materials》2019,29(8)
The goal of human‐on‐a‐chip systems is to capture multiorgan complexity and predict the human response to compounds within physiologically relevant platforms. The generation and characterization of such systems is currently a focal point of research given the long‐standing inadequacies of conventional techniques for predicting human outcome. Functional systems can measure and quantify key cellular mechanisms that correlate with the physiological status of a tissue, and can be used to evaluate therapeutic challenges utilizing many of the same endpoints used in animal experiments or clinical trials. Culturing multiple organ compartments in a platform creates a more physiologic environment (organ–organ communication). Here is reported a human 4‐organ system composed of heart, liver, skeletal muscle, and nervous system modules that maintains cellular viability and function over 28 days in serum‐free conditions using a pumpless system. The integration of noninvasive electrical evaluation of neurons and cardiac cells and mechanical determination of cardiac and skeletal muscle contraction allows the monitoring of cellular function, especially for chronic toxicity studies in vitro. The 28‐day period is the minimum timeframe for animal studies to evaluate repeat dose toxicity. This technology can be a relevant alternative to animal testing by monitoring multiorgan function upon long‐term chemical exposure. 相似文献
123.
We studied the occurrence, removal, and fate of 16 polycyclic aromatic hydrocarbons (PAHs) and 23 volatile organic compounds (VOCs) in Italian municipal wastewater treatment systems in terms of their common contents and forms, and their apparent and actual removal in both conventional activated-sludge processes (CASP) and membrane bioreactors (MBRs). We studied five representative full-scale CASP treatment plants (design capacities of 12 000 to 700 000 population-equivalent), three of which included MBR systems (one full-scale and two pilot-scale) operating in parallel with the conventional systems. We studied the solid-liquid partitioning and fates of these substances using both conventional samples and a novel membrane-equipped automatic sampler. Among the VOCs, toluene, ethylbenzene, xylenes, styrene, 1,2,4-trimethylbenzene, and 4-chlorotoluene were ubiquitous, whereas naphthalene, acenaphthene, fluorene, and phenanthrene were the most common PAHs. Both PAHs and aromatic VOCs had removal efficiencies of 40-60% in the headworks, even in plants without primary sedimentation. Mainly due to volatilization, aromatic VOCs had comparable removal efficiencies in CASP and MBRs, even for different sludge ages. MBRs did not enhance the retention of PAHs sorbed to suspended particulates compared with CASPs. On the other hand, the specific daily accumulation of PAHs in the MBR’s activated sludge decreased logarithmically with increasing sludge age, indicating enhanced biodegradation of PAHs. The PAH and aromatic VOC contents in the final effluent are not a major driver for widespread municipal adoption of MBRs, but MBRs may enhance the biodegradation of PAHs and their removal from the environment. 相似文献
124.
Biodegradation of sulfamethazine by Trametes versicolor: Removal from sewage sludge and identification of intermediate products by UPLC-QqTOF-MS 总被引:1,自引:0,他引:1
García-Galán MJ Rodríguez-Rodríguez CE Vicent T Caminal G Díaz-Cruz MS Barceló D 《The Science of the total environment》2011,409(24):5505-5512
Degradation of the sulfonamide sulfamethazine (SMZ) by the white-rot fungus Trametes versicolor was assessed. Elimination was achieved to nearly undetectable levels after 20 h in liquid medium when SMZ was added at 9 mg L− 1. Experiments with purified laccase and laccase-mediators resulted in almost complete removal. On the other hand, inhibition of SMZ degradation was observed when piperonilbutoxide, a cytochrome P450-inhibitor, was added to the fungal cultures. UPLC-QqTOF-MS analysis allowed the identification and confirmation of 4 different SMZ degradation intermediates produced by fungal cultures or purified laccase: desulfo-SMZ, N4-formyl-SMZ, N4-hydroxy-SMZ and desamino-SMZ; nonetheless SMZ mineralization was not demonstrated with the isotopically labeled sulfamethazine-phenyl-13C6 after 7 days. Inoculation of T. versicolor to sterilized sewage sludge in solid-phase systems showed complete elimination of SMZ and also of other sulfonamides (sulfapyridine, sulfathiazole) at real environmental concentrations, making this fungus an interesting candidate for further remediation research. 相似文献
125.
Pérez AA Farías SS Strobl AM Pérez LB López CM Piñeiro A Roses O Fajardo MA 《The Science of the total environment》2007,376(1-3):51-59
Baseline concentration levels of As, B, Ca, Cd, Cr, Cu, Co, Fe, Mg, Mn, Mo, Ni, P, Pb, Se, V, and Zn were determined for Porphyra columbina and Ulva sp. collected from three locations along San Jorge Gulf, in Patagonia Argentina. Elements were quantified by inductively coupled plasma-optical emission spectrometry, with the exception of lead and cadmium in some samples which were determined by electrothermal atomic absorption spectrometry. Three stations with different exposure degree to human activities, Bahía Solano, the mouth of Arroyo La Mata stream and Punta Maqueda, were selected as sampling points. The results showed a wide range of metal retention capacity between the two studied species. Regarding the levels of pollutants found in the researched sites, Punta Maqueda seemed to be less influenced by anthropogenic activities than the other two sites except for Cd. Taking into account their toxicities seasonal variations in Pb and Cd levels were studied in both algae in Punta Maqueda. Maximum concentrations of Cd (9.8 microg g(-1) dry wt.) were observed in P. columbina during winter, and maximum levels of Pb (0.82 microg g(-1) dry wt.) were detected in Ulva sp. during summer. Legislative and health safety aspects were evaluated for Cd and Pb. 相似文献
126.
127.
Iliescu Florina Silvia Teo Jeremy Choon Meng Vrtacnik Danilo Taylor Hayden Iliescu Ciprian 《Microsystem Technologies》2018,24(7):2905-2912
Microsystem Technologies - Cell transplantation traditionally employs needles to inject donor cells into tissues to treat certain diseases. However, it is difficult for the current method to... 相似文献
128.
129.
130.
Luca Cecchinato Marco Corradi Silvia Minetto 《International Journal of Thermal Sciences》2011,50(12):2483-2495
The prediction of the performances of CO2 transcritical heat pumps demands accurate calculation methods, where a particular effort is devoted to the gas cooler modelling, as the correlation between high pressure and gas cooler outlet temperature strongly affects the cycle performance. The above-mentioned methods require a large amount of input data and calculation power. As a consequence they are often useless for the full characterisation of heat pumps which are sold on the market.A simplified numerical method for the performance prediction of vapour compression heat pumps working in a transcritical cycle is presented, based only on performance data at the nominal rating conditions. The proposed procedure was validated against experimental data of two different tap water heat pumps. For the considered units, simulation results are in good agreement with the experimental ones. The deviations range from −6.4% to +1.7% and from −3.8% to +5.8% for the COPH of the air/water heat pump and the water/water heat pump, respectively. The heating capacity deviations stayed within −5.5% and +1.7% range and within −5.0% and +7.9% range for the same units.The proposed mathematical model appears to be a reliable tool to be used by the refrigeration industry or to be implemented into dynamic building-plant energy simulation codes. Finally, it represents a useful instrument for the definition of tailored approximated optimal high pressure curve considering the operating characteristics of the specific CO2 transcritical unit. It could also be implemented on board of a real unit control system where it could be used as model coupled to computational intelligence algorithms for pressure optimisation. 相似文献