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101.
Thomas Uchida Alfonso Callejo Javier García de Jalón John McPhee 《Multibody System Dynamics》2014,31(3):371-392
Efficient dynamic simulation code is essential in many situations (including hardware-in-the-loop and model-predictive control applications), and highly beneficial in others (such as design optimization, sensitivity analysis, parameter identification, and controller tuning tasks). When the number of modeling coordinates n exceeds the degrees-of-freedom of the system f, as is often the case when closed kinematic chains are present, the governing dynamic equations consist of n second-order ordinary differential equations (ODEs) coupled with m=n?f algebraic constraint equations. This set of n+m index-3 differential-algebraic equations can be difficult to solve in an efficient yet accurate manner. Embedding (or generalized coordinate partitioning) can be used to obtain f ODEs (one for each independent acceleration), which are generally more amenable to numerical integration; however, the dependent positions are typically computed from the independent positions at each time step. Newton–Raphson iteration is often used for solving the position-level kinematics, but only provides solutions to within a specified tolerance, and can require several iterations to converge. In this work, Gröbner bases are used to obtain recursively solvable symbolic solutions for the dependent positions, which can then be evaluated to within machine precision using a fixed number of arithmetic operations. Natural coordinates are particularly attractive in this context, since the resulting constraint equations are maximally quadratic polynomials and are, therefore, easily triangularized. The proposed approach is suitable for use in an automated formulation procedure and, as demonstrated by three examples, is capable of generating highly efficient simulation code with minimal additional effort required at the formulation stage. 相似文献
102.
Masagkazu Saito Hirotoshi Asano Masafumi Uchida Hideto Ide 《Artificial Life and Robotics》2009,14(1):76-79
The use of an agent in the environment, as in medical treatment, welfare, the construction field, and the home, is examined.
It is necessary for the agent to be able to work cooperatively with a human, and that may be a problem. Therefore, this study
pays attention to the phenomenon that is called entrainment. This is the phenomenon where the rhythm of a certain person and
the partner in the communication is synchronized. The purpose of this study is to perform a basic examination into applying
an entrainment in order to realize cooperation in operations between a human and an agent. Since many human rhythms are expressed
by a nonlinear oscillator, we simulated limited cycle oscillators, which are one of two nonlinear oscillators that cause interactions
between agents, as the basic examination for this achievement. Consequently, entrainment of limited cycle oscillators with
rhythms which differ has been checked in certain conditions. As a result, the possibility that cooperative movement could
be gained was suggested. 相似文献
103.
Shunsuke Sakurai Masayasu Inaguma Don N. Futaba Motoo Yumura Kenji Hata 《Small (Weinheim an der Bergstrasse, Germany)》2013,9(21):3584-3592
A continuous and wide range control of the diameter (1.9?3.2 nm) and density (0.03?0.11 g cm?3) of single‐walled carbon nanotube (SWNT) forests is demonstrated by decoupling the catalyst formation and SWNT growth processes. Specifically, by managing the catalyst formation temperature and H2 exposure, the redistribution of the Fe catalyst thin film into nanoparticles is controlled while a fixed growth condition preserved the growth yield. The diameter and density are inversely correlated, where low/high density forests would consist of large/small diameter SWNTs, which is proposed as a general rule for the structural control of SWNT forests. The catalyst formation process is modeled by considering the competing processes, Ostwald ripening, and subsurface diffusion, where the dominant mechanism is found to be Ostwald ripening. Specifically, H2 exposure increases catalyst surface energy and decreases diameter, while increased temperature leads to increased diffusion on the surface and an increase in diameter. 相似文献
104.
Noda K. Tatsumi T. Uchida T. Nakajima K. Miyamoto H. Chenming Hu 《Electron Devices, IEEE Transactions on》1998,45(4):809-814
A simple fabrication technology for delta-doped MOSFETs, named post-low-energy implanting selective epitaxy (PLISE) is presented. The PLISE technology needs no additional photo-lithography mask, deposition step or etching step even for CMOS devices. The only additional step is growing undoped epitaxial channel layers by UHV-CVD after the channel implantation. With this technology, delta-doped NMOSFETs with 0.1-μm gate length were successfully fabricated. By optimizing the epi-layer thickness and the channel doping level, short-channel effects are suppressed enough to achieve 0.1-μm gate length. Moreover, the junction capacitance at zero bias is reduced by 50% 相似文献
105.
106.
The visual simulation of natural phenomena has been widely studied. Although several methods have been proposed to simulate melting, the flows of meltwater drops on the surfaces of objects are not taken into account. In this paper, we propose a particle‐based method for the simulation of the melting and freezing of ice objects and the interactions between ice and fluids. To simulate the flow of meltwater on ice and the formation of water droplets, a simple interfacial tension is proposed, which can be easily incorporated into common particle‐based simulation methods such as Smoothed Particle Hydrodynamics. The computations of heat transfer, the phase transition between ice and water, the interactions between ice and fluids, and the separation of ice due to melting are further accelerated by implementing our method using CUDA. We demonstrate our simulation and rendering method for depicting melting ice at interactive frame‐rates. 相似文献
107.
Nonsalt 1‐(arylmethyloxy)pyrene photoinitiators capable of initiating cationic polymerization 下载免费PDF全文
Analysis of photoproducts derived from 1‐(methoxynaphthalen‐1‐ylmethyloxy)pyrene initiators and polymer end groups demonstrated that methoxynaphthalen‐1‐ylmethyl carbocation is involved in the initiation steps for both styrene (St) and cyclohexene oxide (CHO) polymerization. Charge transfer from the pyrenyloxy oxygen atom to the methoxynaphthalen‐1‐ylmethyl chromophore in the singlet excited state is assumed to be responsible for the efficient generation of the carbocation species, which also initiates the copolymerization of St and CHO. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40510. 相似文献
108.
109.
Iron powders were oxidized in NaOH solutions of 5–25 mol kg–1 at 403–563 K and 5 MPa of oxygen partial pressure. Various types and morphologies of iron compounds such as fine particles of Fe3O4, micaceous -Fe2O3, and coagulated particles of -NaFeO2 were formed depending on the experimental conditions. The observed critical concentrations of NaOH above which -NaFeO2 was formed was in good agreement with those thermodynamically calculated for the hydrolysis equilibrium of -NaFeO2. 相似文献
110.
Th. Braun M. Wohlers T. Belz G. Nowitzke G. Wortmann Y. Uchida N. Pfänder R. Schlögl 《Catalysis Letters》1997,43(3-4):167-173
The influence of fullerenes and related support materials on the structural and catalytic properties of ruthenium was investigated.
Catalysts based on C60, raw fullerene black, extracted fullerene black, cathode deposit and graphite were prepared by an impregnation/activation
procedure with Ru3CO12. The local co-ordination sphere of the resulting highly dispersed X-ray amorphous ruthenium was investigated by means of
EXAFS. The dominating role of the presence of non-six-membered carbon rings on the structure and the stability of the Ru particles
will be illustrated.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献