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991.
本研究推荐制动系统测功器数学模型用来鉴定制动转矩的变化(BTV),并确定动态试验和仿真间的相互关系,介绍了衬垫和盘之间简单模拟,作为点接触元件以及在时间范围内瞬态响应分析。该模型指出BTV的总量与衬垫刚度,摩擦系数,制动盘厚度变化和制动衬垫的有效半径成线性正比例,采用-制动测力器和附加的材料试验进行证实分析模型,动态试验表明所推荐的模型对预测-制动系统BTV具有合理的精确度。 相似文献
992.
Chang-Won Kim Wi Sung Yoo Hyunsu Lim Ilhan Yu Hunhee Cho Kyung-In Kang 《International Journal of Project Management》2018,36(5):730-743
An early-warning performance monitoring system (EPMS) is proposed to objectively measure and monitor the performance of a project for early detection of inherent poor performance problems. The EPMS is built based on project progress data and consists of a database of business information, an optimized theoretical model used as a performance measurement baseline, and an index for monitoring and forecasting the performance. By monitoring the performance through an application of the EPMS to the Korean construction project, the quarterly variation of index was found to differ by project type. These results could explain the environmental changes in the project execution. Therefore, the EPMS is expected to be an alternative for objective performance monitoring and forecasting while applying the existing methods is difficult because of the limited available data on performance indicators. The development procedures may also be useful to researchers interested in approaches to quantitatively analyze trends in various industries. 相似文献
993.
994.
Atomistic Origin of the Enhanced Crystallization Speed and n‐Type Conductivity in Bi‐doped Ge‐Sb‐Te Phase‐Change Materials 下载免费PDF全文
Jonathan M. Skelton Anuradha R. Pallipurath Tae‐Hoon Lee Stephen R. Elliott 《Advanced functional materials》2014,24(46):7291-7300
Phase‐change alloys are the functional materials at the heart of an emerging digital‐storage technology. The GeTe‐Sb2Te3 pseudo‐binary systems, in particular the composition Ge2Sb2Te5 (GST), are one of a handful of materials which meet the unique requirements of a stable amorphous phase, rapid amorphous‐to‐crystalline phase transition, and significant contrasts in optical and electrical properties between material states. The properties of GST can be optimized by doping with p‐block elements, of which Bi has interesting effects on the crystallization kinetics and electrical properties. A comprehensive simulational study of Bi‐doped GST is carried out, looking at trends in behavior and properties as a function of dopant concentration. The results reveal how Bi integrates into the host matrix, and provide insight into its enhancement of the crystallization speed. A straightforward explanation is proposed for the reversal of the charge‐carrier sign beyond a critical doping threshold. The effect of Bi on the optical properties of GST is also investigated. The microscopic insight from this study may assist in the future selection of dopants to optimize the phase‐change properties of GST, and also of other PCMs, and the general methods employed in this work should be applicable to the study of related materials, for example, doped chalcogenide glasses. 相似文献
995.
Liqun Wang Xiaocheng Li Tieming Guo Xingbin Yan Beng Kang Tay 《International Journal of Hydrogen Energy》2014
Supercapacitor, known as an important energy storage device, is also a critical component for next generation of hydrogen fuel cell vehicles. In this study, we report a novel route for synthesis of three-dimensional Ni(OH)2/graphene/nickel foam electrode by electrochemical depositing Ni(OH)2 nanoflakes on graphene network grown on nickel foam current collector and explore its applications in supercapacitors. The resulting binder-free Ni(OH)2/graphene/nickel foam electrode exhibits excellent supercapacitor performance with a specific capacitance of 2161 F/g at a current density of 3 A/g. Even as the current density reaches up to 60 A/g, it still remains a high capacitance of 1520 F/g, which is much higher than that of Ni(OH)2/nickel foam electrode. The enhanced rate capability performance of Ni(OH)2/graphene/nickel foam electrode is closely related to the presence of highly conductive graphene layer on nickel foam, which can remarkably boost the charge-transfer process at electrolyte–electrode interface. The three-dimensional graphene/nickel foam substrate also significantly improves the electrochemical cycling stability of the electrodeposited Ni(OH)2 film because of the strong adhesion between graphene film and electrodeposited Ni(OH)2 nanoflakes. Results of this study provide an alternative pathway to improve the rate capability and cycling stability of Ni(OH)2 nanostructure electrode and offer a great promise for its applications in supercapacitors. 相似文献
996.
CuMgAlCe mixed oxides were prepared by a modified coprecipitation–calcination method using CTAB as surfactant template. All the precursors showed hydrotalcite-like layered structure and mixed oxides with mainly periclase phase were obtained after calcination. Catalytic activity for SO2 removal of mixed oxides was examined through adsorption–reduction cycles under the conditions similar to those of FCC units. The results showed that incorporation of both Ce and Cu could improve SOx oxidative chemisorption. CTAB/metal molar ratio during synthesis had a significant influence on the structural properties of mixed oxides. Sample CuMgAlCe-0.1 prepared by CTAB/metal molar ratio of 0.1 had the highest specific area 142.2 m2/g and also presented the best SO2 adsorption rate and capacity. This behavior is mainly due to its exposed more adsorption sites provided by high specific surface area, facilitating SO2 diffusion and contact with active components. It still possessed excellent cyclic stability that is beneficial for industrial application. 相似文献
997.
Dong Hoon Oh Yi-Dong Yan Dong Wuk Kim Jong Oh Kim Chul Soon Yong 《Drug development and industrial pharmacy》2014,40(2):172-177
Objective: A novel flurbiprofen-loaded nanoemulsion which gave uniform emulsion droplets with a narrow size distribution was previously reported to be prepared using membrane emulsification method. The purpose of this study is to develop a novel flurbiprofen-loaded nanoparticle with a narrow size distribution and improved bioavailability.Method: The nanoparticle was prepared by solidifying nanoemulsion using sucrose as a carrier via spray drying method. Its physicochemical properties were investigated using SEM, DSC and PXRD. Furthermore, dissolution and bioavailability in rats were evaluated compared to a flurbiprofen-loaded commercial product.Results: The flurbiprofen-loaded nanoparticles with flurbiprofen/sucrose/surfactant mixture (1/20/2, weight ratio) gave good solidification and no stickiness. They associated with about 70?000-fold improved drug solubility and had a mean size of about 300 nm with a narrow size distribution. Flurbiprofen was present in a changed amorphous state in these nanoparticles. Moreover, the nanoparticles gave significantly shorter Tmax, and higher AUC and Cmax of the drug compared to the commercial product (p?0.05). In particular, they showed about nine-fold higher AUC of the drug than did the commercial productConclusion: These flurbiprofen-loaded nanoparticles prepared with sucrose by the membrane emulsification and spray drying method would be a potential candidate for orally delivering poorly water-soluble flurbiprofen with enhanced bioavailability. 相似文献
998.
Changwoo Lee Hyunkyoo Kang Keehyun Shin 《Journal of Mechanical Science and Technology》2010,24(5):1097-1103
The mathematical model for tension in a moving web by Shin [1] was extended by considering thermal strain due to temperature
fluctuations in the drying of a roll-to-roll system. The extended model describes variations in tension and includes terms
that represent the change of the Young’s Modulus, the thermal coefficient, and the thermal strain. In this paper, a new control
scheme based on the extended model is proposed for mitigation of tension disturbances due to thermal strain in the drying
process. Tension feedback control logic generally is not be applied due to the fact that register errors can be induced by
speed alterations that help to compensate for tension disturbances. But in our approach, the thermal strain in the web is
compensated for by means of velocity adjustments without adding extra register errors in the steady state. A computer simulation
followed by an experimental validation was carried out to confirm the performance of the proposed method. The results show
that the proposed model is useful for describing tension behavior and suggest that tension control logic improves control
precision for the drying module of a roll-to-roll e-printing system. 相似文献
999.
Ki-Young Shin Yong Hoon Rim Youn Soo Kim Hyo Shin Kim Jae Woong Han Chang Hyun Choi Kyung Suk Lee Joung Hwan Mun 《Journal of Mechanical Science and Technology》2010,24(9):1901-1909
Gait analysis using 3D motion capture systems provides joint kinematic and kinetic analysis results such as joint relative
angles and moments that can be use used to evaluate the degrees of pathological gait patterns. However, the complex data produced
using these 3D motion capture systems can only analyzed by experts, because the gait analysis is highly coupled to the kinematics
of each joint. Therefore, several Several previous studies using gait analysis have relied on the data compression technique
to represent gait deviation from the average normal profiles as a single value. Even though it is important to evaluate gait
pathologies at the joint level, all these previous studies have just used a single value to evaluate the pathological gait
pattern. Using just one variable for evaluation of a gait is limited in terms of determining which joint movement patterns
are getting better during rehabilitation. Therefore, in this study, a method suitable for evaluating gait deviation during
a gait was developed to provide three indices for the hip, knee and ankle joints. In addition, to validate the proposed method
in clinical cases, experimental tests were conducted on thirty thirty-six normal walkers and six patients with cerebral palsy.
Furthermore, to validate the proposed method in regards to rehabilitation, experimental tests were conducted on three classified
walking groups with imposed ankle equinus constraints. The JNI for the hip joint, knee joint and ankle were 8.78 (±3.70),
2.92 (±3.25) and 8.79 (±4.38), respectively, in the normal walking group. However, these values were significantly different
for the pathological walking group with cerebral palsy. The JNI of the hip joint, knee joint and ankle joint were 203.73 (±171.59),
81.23 (±52.13) and 248.39 (±149.99), respectively, for this group. There were also differences between any two of the three
classified groups with imposed ankle equinus constraints. In particular, the JNI of the ankle joint was statistically different
at the p<0.01 level, and this parameter clearly increased as the degree of the imposed ankle equinus was increased. These
results demonstrate that the proposed JNI can be used as a scalar factor to evaluate the angular deviation of each joint in
normal and patient groups. In addition, this approach can be adapted to evaluate rehabilitation and pre/post surgery. 相似文献
1000.
The objective of this study was to investigate the correlation of phenolic compositions and corrosion inhibition properties of Rhizophora apiculata bark extracts as affected by nine solvent systems. Several phenolic compositions, namely, total phenolic content (TPC), total flavonoid content (TFC), condensed tannin content (CTC) were investigated. In addition, the inhibitive actions of tannin extracts on mild steel in 1 M HCl solution were studied by potentiodynamic polarization and electrochemical impedance spectroscopy. The results showed that extraction solvents had significant effects on TPC, TFC, CTC and inhibition properties of extracts. A correlation between CTC and inhibition properties of R. apiculata bark extracts was revealed. 相似文献