全文获取类型
收费全文 | 1530篇 |
免费 | 101篇 |
国内免费 | 7篇 |
学科分类
工业技术 | 1638篇 |
出版年
2024年 | 3篇 |
2023年 | 38篇 |
2022年 | 51篇 |
2021年 | 101篇 |
2020年 | 70篇 |
2019年 | 55篇 |
2018年 | 86篇 |
2017年 | 79篇 |
2016年 | 80篇 |
2015年 | 43篇 |
2014年 | 64篇 |
2013年 | 130篇 |
2012年 | 97篇 |
2011年 | 110篇 |
2010年 | 63篇 |
2009年 | 77篇 |
2008年 | 61篇 |
2007年 | 73篇 |
2006年 | 51篇 |
2005年 | 36篇 |
2004年 | 30篇 |
2003年 | 28篇 |
2002年 | 14篇 |
2001年 | 7篇 |
2000年 | 13篇 |
1999年 | 12篇 |
1998年 | 9篇 |
1997年 | 16篇 |
1996年 | 11篇 |
1995年 | 16篇 |
1994年 | 10篇 |
1993年 | 14篇 |
1992年 | 9篇 |
1991年 | 11篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1982年 | 3篇 |
1981年 | 8篇 |
1980年 | 1篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1970年 | 2篇 |
排序方式: 共有1638条查询结果,搜索用时 836 毫秒
91.
Catalysis Letters - Herein, polyphenol oxidase (PPO) was purified from Coleus forskohlii via a three-step process involving precipitation by (NH4)2SO4, ion exchange chromatography and gel... 相似文献
92.
Journal of Mechanical Science and Technology - Braking system is one of the basic organs to control a car. For many years, the disc brakes have been used in automobiles for safe retardation of the... 相似文献
93.
Víctor M. Ovando‐Medina Josu Vizcaíno‐Mercado Omar Gonzlez‐Ortega Jos A. Rodríguez de la Garza Hugo Martínez‐Gutirrez 《Polymer Composites》2015,36(2):312-321
In this work, a composite from α‐cellulose coated with conducting polypyrrole by in situ polymerization using potassium persulfate as oxidant was obtained. The composite was characterized by fourier transform infrared (FTIR) spectroscopy, cyclic voltammetry, UV/Vis spectroscopy, and scanning electron microscopy (SEM) analysis showed homogeneous coating of α‐cellulose with polypyrrole (PPy) to produce a composite with a conductivity of 3.5 × 10−5 S/m. Batch aqueous adsorption experiments of the reactive red 120 (RR120) dye onto the synthesized material were conducted. The results showed that this composite is an efficient adsorbent for RR120 dye removal. For the adsorption experiments set to an initial pH of 3.9, the adsorption capacity was 15.6 mg of dye/g of composite for an equilibrium concentration (in the liquid) of RR120 dye equal to 1,000 mg/L, whereas a value of 96.1 mg of dye/g of composite was obtained when the solution pH was set to 2.0 for the same equilibrium concentration. When performing adsorption experiments using pure α‐cellulose, dye adsorption was insignificant at any pH value. Adsorption isotherm for RR120 was described by a typical Freundlich model. The transient adsorption of RR120 on the synthesized composite was described by a general three‐resistance model that includes the transport on the film that surrounds the composite particles, diffusion inside the particles, and adsorption on the surface of the particles. A fitting of the uptake curves was performed allowing the estimation of values for the effective diffusivity, D0, and the adsorption rate coefficient, k1. For the adsorption experiments with an initial pH value set to 3.9, D0 was estimated as 1.05 × 10−10 m2/s, whereas k1 was 1.65 × 10−4 Ln/g mgn − 1 s; the corresponding values of k1 at pH = 2 and 9.0 were 3.18 × 10−4 and 5.16 × 10−5, respectively. POLYM. COMPOS., 36:312–321, 2015. © 2014 Society of Plastics Engineers 相似文献
94.
Omar A. Elgendy Mahmoud H. Ismail Khaled M. F. Elsayed 《Telecommunication Systems》2018,68(4):643-655
One of the major issues in LTE-Advanced (LTE-A) systems is the poor capacity at the cell edge. This is mainly due to the interference experienced by the users as a result of the aggressive frequency reuse usually implemented. Relaying offers an attractive solution for this problem by offering better links than those with the eNodeB (eNB) for the terminals suffering from high path loss or high interference. However, adding relays complicates the resource allocation problem at the eNB and therefore the need for more efficient schemes arises. This is also aggravated by the reuse of resource blocks (RBs) by the relays to fully exploit the scarce spectrum, which, in turn, leads to intra-cell interference. In this paper, we study the joint power and resource allocation problem in LTE-A relay-enhanced cells that exploit spatial reuse. To guarantee fairness among users, a max–min fair optimization objective is used. This complex problem is solved using coordinate ascent and the difference of two convex functions (DC) programming techniques and the proposed scheme indeed converges to a local-optimum quickly. This is shown to be a satisfactory solution according to the simulation results that indicate an almost sevenfold increase in the 10th percentile capacity when compared to previously proposed solutions. 相似文献
95.
Hend Omar Mohamed Enas Taha Sayed M. Obaid Yun-Jeong Choi Sung-Gwan Park Siham Al-Qaradawi Kyu-Jung Chae 《International Journal of Hydrogen Energy》2018,43(46):21560-21571
The poor wettability and high cost of the carbonaceous electrodes materials prohibited the practical applications of microbial fuel cells (MFCs) on large scale. Here, a novel nanoparticles of metal sheathed with metal oxide is electrodeposited on carbon paper (CP) to introduce as high-performance anodes of microbial fuel cell (MFC). This thin layer of metal/metal oxide significantly enhance the microbial adhesion, the wettability of the anode surface and decrease the electron transfer resistance. The investigation of the modified CP anodes in an air-cathode MFCs fed by various biocatalyst cultures shows a significant improving in the MFC performance. Where, the generated power and current density was 140% and 210% higher as compared to the pristine CP. Mixed culture of exoelectrogenic microorganism in wastewater exhibited good performance and generated higher power and current density compared to yeast as pure culture. The excellent capacitance with a distinctive nanostructure morphology of the modified-CP open an avenues for practical applications of MFCs. 相似文献
96.
A simple, one-step slurry coating technique was used to aluminize open cell nickel metal foam at low temperature and short hold-down time. Three slurries of different composition, heat-treated at 650 °C for 2 h, were used to investigate the possibility of developing an aluminide coating on a commercially produced Ni foam. In all cases a dense, well-adhered to the Ni substrate aluminide coating of several μm thickness was produced. The thickness and aluminide phase and composition (NiAl and/or Ni3Al) of the coating strongly depend on Al content and the mix of activators in the slurry. 相似文献
97.
Ouardia Zamoume Sophie Thibault Gwenaël Regnié Med Omar Mecherri Marina Fiallo Patrick Sharrock 《Materials science & engineering. C, Materials for biological applications》2011,31(7):1352-1356
Limited blood circulation to the skeletal tissue is a major cause of reduced therapeutic effects seen with drugs administered by conventional systemic ways. To resolve this issue and obtain a sufficiently high local concentration to induce therapeutic effects, several implanted drug delivery systems have been developed for hard tissues using biomaterials.We have designed a drug delivery device based on hydroxylapatite (HA) and tested it in vitro using metronidazol and chloramphenicol as model compounds. Porous HA ceramics were prepared with two different shapes (cylindrical and spherical). Known amounts of drugs were introduced inside a drilled hole and sealed with wax. The ceramics were then suspended in stirred distilled water in closed polypropylene vials. Drug release was observed during several weeks.A mathematical model used to describe drug release from HA was elaborated based on the expressions of Fick's laws. The experimental kinetic results could be related to ceramic constitution and to drug localization. 相似文献
98.
Kamel Eddine El Mecherfi Djamel Saidi Omar Kheroua Ghazalia Boudraa Mahmoud Touhami Olivier Rouaud S��bastien Curet Yvan Choiset Hanitra Rabesona Jean-Marc Chobert Thomas Haertl�� 《European Food Research and Technology》2011,233(5):859-867
Effect of combined microwave (MW) and enzymatic hydrolysis on the human immunoglobulin E (IgE)-binding properties of ??-lactoglobulin (??-lg) and other whey proteins (WP) was investigated. Separated ??-lg and full whey protein isolate (WPI) were hydrolyzed with trypsin, chymotrypsin, mixture of trypsin/chymotrypsin, and pepsin at three microwave power levels: 50?W during 1 and 5?min, 100 and 200?W during 1 and 3?min. The immunoreactivity of the obtained hydrolysates resulting from combined microwave protease treatment was assessed using sera of young patients allergic to bovine whey proteins. The application of microwave treatment at 200?W enhances the hydrolysis of ??-lg by pepsin in 3?min and decreases significantly its immunoreactivity. The extensive hydrolysis of the microwave-treated ??-lg and WPI with trypsin, chymotrypsin, and the mixture of trypsin with chymotrypsin did not have an impact on the IgE binding of the products obtained in all the studied conditions. 相似文献
99.
This article presents solar energy or specifically the solar photovoltaic (PV) development outlook in Malaysia. The paper first introduces the massive potential of solar energy in the country, the key players in the solar energy development and the early solar energy policies, and programmes in the country. The most important to the PV development is the Malaysia Building Integrated Photovoltaic initiative, which is presented in this paper followed by an explanation on the Feed-in Tariff recently introduced in the country to encourage new solar PV projects. The outlook for solar PV in Malaysia is optimistic and as the uptake of solar PV increases, the unit cost is coming down rapidly. Solar PV is expected to be the most competitive Renewable Energy (RE) source, with the potential to achieve grid parity for electrical power in the country in the near future, and surpassing all other REs combined by 2050. 相似文献
100.
This research work focuses on the utilization of coconut shell powder (CSP) as filler in recycled polypropylene (rPP). Sodium Dedecyl Sulfate (SDS) was used as coupling agent in these composites. The effect of filler content and SDS on tensile properties, thermal properties, water absorption and morphology of rPP/CSP composites were investigated. In this study, modified rPP/CSP composites with SDS show significant increased tensile propertied, thermal stability, crystallinity and low water absorption compared unmodified rPP/CSP composites. Those improvements were contributed by the coupling effect of SDS. 相似文献