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141.
142.
S. Nakamura K. Suzuki M. Ataka H. Fujita S. Basrour V. Soumann M. Labachelerie W. Daniau 《Microsystem Technologies》1998,5(2):69-71
We demonstrate an electrostatic micro actuator which is fabricated by LIGA process. The actuator is designed for a magnetic
head tracking system of hard disk drives (HDDs). The actuator is essential to achieve very high track density of HDDs. We
realize the aspect ratio of 125 by the LIGA process using a Si-Au mask. We propose to use PMMA molds both as the mechanical
structure and as the insulator between electrodes. We believe there are great opportunity for the LIGA process in making micro
actuators of HDDs.
Received: 25 August 1997 / Accepted: 24 October 1997 相似文献
143.
Atsuyoshi Nakamura Jun-ichi Takeuchi Naoki Abe 《Annals of Mathematics and Artificial Intelligence》1998,23(1-2):53-82
We consider a variant of the ‘population learning model’ proposed by Kearns and Seung [8], in which the learner is required
to be ‘distribution-free’ as well as computationally efficient. A population learner receives as input hypotheses from a large
population of agents and produces as output its final hypothesis. Each agent is assumed to independently obtain labeled sample
for the target concept and output a hypothesis. A polynomial time population learner is said to PAC-learn a concept class,
if its hypothesis is probably approximately correct whenever the population size exceeds a certain bound which is polynomial,
even if the sample size for each agent is fixed at some constant. We exhibit some general population learning strategies,
and some simple concept classes that can be learned by them. These strategies include the ‘supremum hypothesis finder’, the
‘minimum superset finder’ (a special case of the ‘supremum hypothesis finder’), and various voting schemes. When coupled with
appropriate agent algorithms, these strategies can learn a variety of simple concept classes, such as the ‘high–low game’,
conjunctions, axis-parallel rectangles and others. We give upper bounds on the required population size for each of these
cases, and show that these systems can be used to obtain a speed up from the ordinary PAC-learning model [11], with appropriate
choices of sample and population sizes. With the population learner restricted to be a voting scheme, what we have is effectively
a model of ‘population prediction’, in which the learner is to predict the value of the target concept at an arbitrarily drawn
point, as a threshold function of the predictions made by its agents on the same point. We show that the population learning
model is strictly more powerful than the population prediction model. Finally, we consider a variant of this model with classification
noise, and exhibit a population learner for the class of conjunctions in this model.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
144.
The multiprocessor scheduling problem is one of the classic examples of NP-hard combinatorial optimization problems. Several
polynomial time optimization algorithms have been proposed for approximating the multiprocessor scheduling problem. In this
paper, we suggest a geneticizedknowledge genetic algorithm (gkGA) as an efficient heuristic approach for solving the multiprocessor
scheduling and other combinatorial optimization problems. The basic idea behind the gkGA approach is that knowledge of the
heuristics to be used in the GA is also geneticized alongiside the genetic chromosomes. We start by providing four conversion
schemes based on heuristics for converting chromosomes into priority lists. Through experimental evaluation, we observe that
the performance of our GA based on each of these schemes is instance-dependent. However, if we simultaneously incorporate
these schemes into our GA through the gkGA approach, simulation results show that the approach is not problem-dependent, and
that the approach outperforms that of the previous GA. We also show the effectiveness of the gkGA approach compared with other
conventional schemes through experimental evaluation.
This work was presented, in part, at the Second International Symposium on Artifiical Life and Robotics, Oita, Japan, February
18–20, 1997 相似文献
145.
Human behaviors consist of both voluntary and involuntary motions. Almost all behaviors of task-oriented robots, however, consist solely of voluntary motions. Involuntary motions are important for generating natural motions like those of humans. Thus, we propose a natural behavior generation method for humanoid robots that is a hybrid generation between voluntary and involuntary motions. The key idea of our method is to control robots with a hybrid controller that combines the functions of a communication behavior controller and body balancing controllers. We also develop a wheeled inverted pendulum type of humanoid robot, named “Robovie-III”, in order to generate involuntary motions like oscillation. By applying our method to this robot and conducting preliminary experiments, we verify its validity. Experimental results show that the robot generates both voluntary and involuntary motions. 相似文献
146.
H. Araki M. Nakamura S. Harada T. Obata N. Mikhin V. Syvokon M. Kubota 《Journal of Low Temperature Physics》2004,134(5-6):1145-1151
Hydrogen in palladium, Pd-H(D), is an interesting system because of the highly mobile hydrogen and the presence of a phase boundary below 100 K. Experimentally, however, the nature of this transition has not been established. Historically this transition around 55 to 100 K has been thought to be an order-disorder transition. Such a transition would produce a phase boundary with anomalies at specific hydrogen concentrations corresponding to the specific ordered structures. In order to check this phase boundary we have performed a detailed study of the hydrogen concentration dependence of the specific heat of PdH x over the temperature range from below 0.5 K to above 100 K using PdH x specimens with x up to 0.8753. The measured heat capacity has been analyzed as the sum of contributions due to the lattice specific heat of Pd, the electronic specific heat of PdH x , and the excess contribution caused by hydrogenation of the specimen. The excess specific heat result shows a sharp peak which indicates a phase boundary with transition temperature T 1=55 K to 85 K depending linearly on the hydrogen concentration from x=0.6572 to 0.8753. We do not observe anomalies at specific x values as would be expected for the specific ordered structures. 相似文献
147.
This paper has described the characteristics of a stationary linear type magnetic flux pump newly developed this time. The linear type flux pump aims to compensate a little decremental persistent current of the HTS magnet in NMR and MRI systems. The flux pump mainly consists of DC bias coil, 3-phase AC coil and Nb foil. Analytical results by the FEM are proved to nearly agree with experimental ones. In the experiment, it has been investigated that the flux pump can effectively charge the current in the load coil of 1.3 mH for various frequencies in 150 s under two following conditions: (1) DC bias of 10 A and AC of 4 Arms, (2) DC bias of 10 A and AC of 5 Arms. The maximum magnitudes of initial increasing rate of pumping current and load magnet voltage are: (1) 0.2 A/s and 25 mV and (2) 0.22 A/s and 34 mV, respectively. 相似文献
148.
KenjiYoshii AkioNakamura MasaichiroMizumaki NaoshiIkeda Jun'ichiroMizuki 《中国稀土学报(英文版)》2004,22(6):733-738
Magnetic properties were investigated for the rare-earth 3d-transition metal oxides with the perovskite structure. Intriguing magnetic phenomena were reviewed for a few systems:magnetization peak effect in the titanates, magnetization reversal in the chromites and metallic ferromagnetism in the cobahites. The results suggest an important role of the rare-earth ions for the magnetic properties of such complex oxides. 相似文献
149.
Zhang Ming CHEN Haiyan Chen Xiaosong Dai Shaojun Inoue Shinich OKAMOTO Hiroshi 《中国稀土学报(英文版)》2004,22(Z3)
Acrylic acid rare earth complex was prepared. Its chemical composition was determined by chemical and elemental analysis, and its structure as well as properties was characterized using IR, Fluorescence and UV spectrum, and its solubility was also investigated. Meanwhile a kind of elastic functional polymer with rare earth units in the side chains was produced. It is confirmed by IR spectrum that the Si-H bonds really react with acrylic acid rare earth. 相似文献
150.
Shun-ichi Nakamura Tetsuya Hosaka Kenji Nishiumi 《Canadian Metallurgical Quarterly》2004,9(3):297-303
Bending behavior of steel pipes filled with ultralight mortar was studied by bending tests using a steel pipe, steel pipes filled with ultralight mortar, and steel pipes filled with light aggregate concrete and normal concrete. The steel pipe model filled with normal concrete had 1.8 times higher bending strength than the steel pipe model. The bending behavior of the steel pipe filled model with ultralight mortar was not improved when the compressive strength of the ultralight mortar was less than 1 MPa. However, ductility was much improved when the compressive strength was over 5 MPa, and the ultimate steel strain was more than double of the steel pipe model. The strains of steel and concrete in all the models were proportional to the distance from the neutral axis until the steel plate yielded. A simple analytical method was proposed to calculate the bending moments of the ultralight mortar filled steel pipes. The calculated values agreed very well with the test results. 相似文献