全文获取类型
收费全文 | 637篇 |
免费 | 34篇 |
专业分类
电工技术 | 20篇 |
化学工业 | 170篇 |
金属工艺 | 5篇 |
机械仪表 | 18篇 |
建筑科学 | 10篇 |
能源动力 | 11篇 |
轻工业 | 96篇 |
水利工程 | 2篇 |
石油天然气 | 8篇 |
无线电 | 89篇 |
一般工业技术 | 77篇 |
冶金工业 | 57篇 |
原子能技术 | 2篇 |
自动化技术 | 106篇 |
出版年
2023年 | 7篇 |
2022年 | 47篇 |
2021年 | 43篇 |
2020年 | 18篇 |
2019年 | 17篇 |
2018年 | 11篇 |
2017年 | 10篇 |
2016年 | 20篇 |
2015年 | 26篇 |
2014年 | 26篇 |
2013年 | 46篇 |
2012年 | 43篇 |
2011年 | 29篇 |
2010年 | 26篇 |
2009年 | 27篇 |
2008年 | 18篇 |
2007年 | 44篇 |
2006年 | 28篇 |
2005年 | 15篇 |
2004年 | 17篇 |
2003年 | 22篇 |
2002年 | 13篇 |
2001年 | 8篇 |
2000年 | 6篇 |
1999年 | 11篇 |
1998年 | 19篇 |
1997年 | 17篇 |
1996年 | 12篇 |
1995年 | 7篇 |
1994年 | 9篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1971年 | 2篇 |
排序方式: 共有671条查询结果,搜索用时 15 毫秒
91.
The discharge/loading process of a single container ship by multiple quay cranes and shuttle vehicles moving back and forth
from the quay to the yard and vice versa is focused in this paper. The core problem of this major operational issue reduces
to finding the optimal assignment and optimal sequencing (schedule) of bays (jobs) processed by a fixed number of available
cranes (machines). Under the classical assumption that machines have no release time and that their processing occurs with
continuity, at a constant rate, in literature it has been tackled as a deterministic machine scheduling problem and formulated
by integer programming as the quay crane scheduling problem (QCSP). Here, instead, the QCSP is viewed as a decisional step within an uncertain and dynamic logistic process where the
quay cranes are the resources to be managed at the best, i.e., by minimizing the time spent waiting for each other due to
conflicts, as well as the time wasted for blocking and starvation phenomena due to congestion occurring along the path from
the quay area and to the stacking yard and vice versa. We present a simulation-based optimization (SO) model for this wider
modeling problem with the objective of finding the schedule which optimizes a classical objective function. The search process
for the optimal schedule is accomplished by a simulated annealing (SA) algorithm, while performance estimation of the overall
container discharge/loading process is provided by the simulation framework as a whole. Numerical experiments on a real instance
are presented for tuning purposes of the SA procedure implemented within the simulator. 相似文献
92.
Two novel process variations aware, necessary and sufficient conditions suitable for implementation in CAD optimizers are proposed to check amplifiers stability. Case studies are presented, showing that the new criteria allow robust amplifier design, under variation of active device immittance parameters in pre‐specified rectangular regions, due to manufacturing tolerances. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 23: 619–626, 2013. 相似文献
93.
An evolutionary procedure based on cultural algorithms for the optimal design of adaptive wavelet filters based on lifting scheme is proposed. Numerical results of characterization, based on statistical experiment design, as well as validation, based on the comparison with a genetic optimization algorithm, are presented. Experimental results of the validation on two case studies for reducing uncertainty arising from noise in on-field corrosion rate measurements are highlighted. 相似文献
94.
The calibration in frequency of piezoelectric transducers can be obtained by sending an ultrashort laser pulse (30 ps), generated by a mode-locked Nd:YAG laser, directly on the detector surface. Thanks to its short duration, the mode-locked pulse behaves as an excitation source of wide spectral content, so that the spectral analysis of the recorded electric signal gives direct information about the frequency response of the probe. In particular, we report a series of measurements on various transducers of several nominal frequencies and we show the different response of the probe to a focused laser beam to that of an unfocused one. 相似文献
95.
Pasquale Russo Spena Manuela De Maddis Franco Lombardi Matteo Rossini 《Materials and Manufacturing Processes》2016,31(3):291-299
Dissimilar resistance spot welding of twinning induced plasticity (TWIP) and quenching and partitioning (Q&P) steel grades has been investigated by evaluating the effects of clamping force, welding current, and welding time on the microstructure, shear tension strength, and fracture of welded samples. The spot welding of TWIP and Q&P steels promotes the occurrence of an asymmetrical weld nugget with a greater dilution of TWIP steel because of its lower melting temperature and thermal conductivity. As a result, weld nuggets exhibit an austenitic microstructure. TWIP steel undergoes a grain coarsening in the HAZ, whereas Q&P steel undergoes some phase transformations. Welded samples tend to exhibit higher shear tension strength as they are joined at the highest welding current, even though an improper clamping force can promote excessive metal expulsion, thereby reducing the mechanical strength of the welded joints. Shear tension welded samples failed through interfacial fracture with partial thickness fracture mode for a low welding current, while partial thickness with button pull fractures were observed when a high welding current was used. The weld spots predominantly failed at the TWIP side. However, as TWIP steel can work harden significantly in the more resistant welded joints, the failures occur, instead, at the Q&P side. 相似文献
96.
Synthetic biology combines different branches of biology and engineering aimed at designing synthetic biological circuits able to replicate emergent properties useful for the biotechnology industry, human health and environment. The role of negative feedback in noise propagation for a basic enzymatic reaction scheme is investigated. Two feedback control schemes on enzyme expression are considered: one from the final product of the pathway activity, the other from the enzyme accumulation. Both schemes are designed to provide the same steady‐state average values of the involved players, in order to evaluate the feedback performances according to the same working mode. Computations are carried out numerically and analytically, the latter allowing to infer information on which model parameter setting leads to a more efficient noise attenuation, according to the chosen scheme. In addition to highlighting the role of the feedback in providing a substantial noise reduction, our investigation concludes that the effect of feedback is enhanced by increasing the promoter sensitivity for both schemes. A further interesting biological insight is that an increase in the promoter sensitivity provides more benefits to the feedback from the product with respect to the feedback from the enzyme, in terms of enlarging the parameter design space.Inspec keywords: biotechnology, enzymes, biological techniquesOther keywords: negative feedback impact, metabolic noise propagation, mathematical modelling, synthetic biological circuit, biotechnology industry, human health, environment, enzymatic reaction scheme, feedback control scheme, enzyme expression, enzyme accumulation, negative autoregulation, steady‐state average value, feedback performance, stochastic simulation algorithm, stochastic hybrid system modelling, noise attenuation, substantial noise reduction, feedback effect, parameter design space 相似文献
97.
Christoph Adler Pasquale Pavone Ulrich Schrder 《Computational Materials Science》2001,20(3-4):371-375
We present a theoretical first-principles investigation of the structure and lattice dynamics of several layered semiconductors. The equilibrium structure as obtained by minimization of the total energy of the bulk materials is in good agreement with experiment. Furthermore, we have investigated the surface of these materials in order to obtain information on the van der Waals epitaxial growth. We found that the relaxed atomic positions at the surface deviate from the ideal ones in the bulk by less than 1%, which is obviously a consequence of the weak interlayer forces. Additionally, bulk phonon-dispersion curves have been calculated along several high symmetry directions within the density-functional perturbation theory (DFPT). The weak interlayer interaction makes the vibrational properties of the bulk very similar to those of the surface. In fact, our ab initio calculations for the bulk reproduce well both the experimental bulk phonon frequencies obtained by inelastic neutron scattering and the experimental surface phonon dispersion measured with inelastic He-atom scattering (HAS). 相似文献
98.
Silvio Borrelli Roberto Minutolo Luca De Nicola Emanuele De Simone Walter De Simone Bruno Zito Pasquale Guastaferro Filippo Nigro Giuseppe Iulianiello Olga Credendino Antonio Bassi Luigi Leone Maria Capuano Maria Rita Auricchio Giuseppe Conte 《Hemodialysis international. International Symposium on Home Hemodialysis》2014,18(4):758-766
Chronic inflammation is widely diffuse in maintenance hemodialysis (MHD) patients and is associated with poor survival. Hemodiafiltration with endogenous reinfusion (HFR) is a dialysis technique, highly biocompatible, able to adsorb proinflammatory cytokines and to decrease amino acids and antioxidants loss. These features could be helpful in MHD patients affected by idiopathic chronic inflammation, but this issue remains to be elucidated. We performed a multicenter longitudinal study to assess the effect of the switching from bicarbonate HD to HFR in patients with serum C‐reactive Protein (CRP) > 5 mg/L coupled with albumin <4.0 g/dL in the last 6 months. We enrolled 24/176 (14%) patients, of which 20 patients were assessed at 4 months and 18 completed the study. We excluded 11 patients with evident causes of inflammation. At baseline, serum levels of CRP (18.7[7.0–39.4] mg/L) and albumin (3.5[3.3–3.7] g/dL) were significantly correlated (r = ?0.49; P = 0.028). The effect on CRP and albumin was almost evident in the first 4 months and remained stable until to eighth month. A strict correlation (R = ?0.49; 0.040) between percentage change of CRP (?35%) and albumin (+14%) after 8 months of HFR. These effects were associated with the reduction of IL‐6, IL‐1β, and TNF‐α and the increment of pre‐albumin and leptin, whereas the serum levels of Branched Chain Amino Acid (BCAA) remained unchanged. In MHD patients affected by idiopathic chronic inflammation the switching from BHD to HFR is associated with improvement of inflammation. Whether these favorable effects may modify the outcomes of these high‐risk patients needs to be confirmed by studies ad hoc. 相似文献
99.
Pasquale Stano Tereza Pereira de Souza Paolo Carrara Emiliano Altamura Erica D’Aguanno Margherita Caputo 《先进材料力学与结构力学》2015,22(9):748-759
Here we report some recent biophysical issues on the preparation of solute-filled lipid vesicles and their relevance to the construction of “synthetic cells.” First, we introduce the “semi-synthetic minimal cells” as the liposome-based cell-like systems, which contain a minimal number of biomolecules required to display simple and complex biological functions. Next, we focus on recent aspects related to the construction of synthetic cells. Emphasis is given to the interplay between the methods of synthetic cell preparation and the physics of solute encapsulation. We briefly introduce the notion of structural and compositional “diversity” in synthetic cell populations. 相似文献
100.