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981.
In last years, Face recognition based on 3D techniques is an emergent technology which has demonstrated better results than
conventional 2D approaches. Using texture (180° multi-view image) and depth maps is supposed to increase the robustness towards
the two main challenges in Face Recognition: Pose and illumination. Nevertheless, 3D data should be acquired under highly
controlled conditions and in most cases depends on the collaboration of the subject to be recognized. Thus, in applications
such as surveillance or control access points, this kind of 3D data may not be available during the recognition process. This
leads to a new paradigm using some mixed 2D-3D face recognition systems where 3D data is used in the training but either 2D
or 3D information can be used in the recognition depending on the scenario. Following this concept, where only part of the
information (partial concept) is used in the recognition, a novel method is presented in this work. This has been called Partial
Principal Component Analysis (P2CA) since they fuse the Partial concept with the fundamentals of the well known PCA algorithm. This strategy has been proven
to be very robust in pose variation scenarios showing that the 3D training process retains all the spatial information of
the face while the 2D picture effectively recovers the face information from the available data. Furthermore, in this work,
a novel approach for the automatic creation of 180° aligned cylindrical projected face images using nine different views is
presented. These face images are created by using a cylindrical approximation for the real object surface. The alignment is
done by applying first a global 2D affine transformation of the image, and afterward a local transformation of the desired
face features using a triangle mesh. This local alignment allows a closer look to the feature properties and not the differences.
Finally, these aligned face images are used for training a pose invariant face recognition approach (P2CA). 相似文献
982.
In this paper, the dynamic behaviors of a class of neural networks with time-varying delays are investigated. Some less weak
sufficient conditions based on p-norm and ∞-norm are obtained to guarantee the existence, uniqueness of the equilibrium point for the addressed neural networks
without impulsive control by applying homeomorphism theory. And then, by utilizing inequality technique, Lyapunov functional
method and the analysis method, some new and useful criteria of the globally exponential stability with respect to the equilibrium
point under impulsive control we assumed are derived based on p-norm and ∞-norm, respectively. Finally, an example with simulation is given to show the effectiveness of the obtained results. 相似文献
983.
Many researches have been devoted to select the kernel parameters, including the centers, kernel width and weights, for fault-free
radial basis function (RBF) neural networks. However, most are concerned with the centers and weights identification, and
fewer focus on the kernel width selection. Moreover, to our knowledge, almost no literature has proposed the effective and
applied method to select the optimal kernel width for faulty RBF neural networks. As is known that the node faults inevitably
take place in real applications, which results in a great many of faulty networks, it will take a lot of time to calculate
the mean prediction error (MPE) for the traditional method, i.e., the test set method. Thus, the letter derives a formula
to estimate the MPE of each candidate width value and then use it to select the optimal one with the lowest MPE value for
faulty RBF neural networks with multi-node open fault. Simulation results show that the chosen optimal kernel width by our
proposed MPE formula is very close to the actual one by the conventional method. Moreover, our proposed MPE formula outperforms
other selection methods used for fault-free neural networks. 相似文献
984.
Space robotic systems are expected to play an increasingly important role in the future on-orbit service. The applications
include repairing, refueling or de-orbiting of a satellite, or removal of the space debris. The dynamical performances of
space robotic system result from the multi-physics interactions between mechanical, electrical, electronic, control, etc.
In this paper, we developed a unified multi-domain modelling and simulation system. The system is composed of the following
modules: the path planner, joint controllers, motor and its driver, gearing mechanism of the space manipulators, the Guidance,
Navigation, and Control (GNC) system, the actuators of the base, and the orbital environment, orbital dynamic and the multi-body
dynamic of the whole system, etc. Based on this system, the operation during different stages, including far range rendezvous,
close range rendezvous (is usually divided into two sub-phases: closing and final approach) and target capturing can be studied
from the view of multi-physics domains. The key algorithms, such as pose (position and attitude) measurement, GNC of the base,
path planning and control of the space manipulator, and so on, can be validated using the system. As examples, the capturing
processes of a moving target under free-floating and attitude-controlled modes are simulated and the simulation results are
given. 相似文献
985.
Nikolay Borissov Dirk Neumann Christof Weinhardt 《Autonomous Agents and Multi-Agent Systems》2010,21(2):115-142
Autonomous agents are widely applied to automate interactions in robotics, e.g. for selling and purchasing goods on eBay,
and in financial markets, e.g. in the form of quote machines and algorithmic traders. Current research investigates efficient
economic mechanisms that fully automate the provisioning and usage processes of Grid-based services. On the one hand, consumers
want to allocate resources on demand for their various applications, e.g. data sharing, stream processing, email, business
applications and simulations. On the other hand, providers of Grid services want to govern business policies to meet their
utilization and profit goals. The above-mentioned processes are not manually manageable, however, because decisions need to
be taken within milliseconds. Therefore, such processes have to be automated to minimize human interactions. Hence, market
mechanisms and strategic behavior play important roles when it comes to achieving automated and efficient allocation of Grid
services. The paper begins by presenting a framework for automated bidding, providing a methodology for the design and implementation
of configurable bidding strategies. Second, it presents a novel bidding strategy based on a reinforcement learning technique.
This strategy is designed to automate the bid generation processes of consumers and providers in various market mechanisms.
Third, the behavior and convergence of the strategy is evaluated in a centralized Continuous Double Auction and a decentralized
on-line machine scheduling mechanism against selected benchmark bidding strategies. Fourth, we define a bidding language for
communicating consumer and provider preferences to the market as well as report back the match of the market-based allocation
process. 相似文献
986.
XMin: Minimizing Tree Pattern Queries with Minimality Guarantee 总被引:1,自引:0,他引:1
Due to wide use of XPath, the problem of efficiently processing XPath queries has recently received a lot of attention. In
particular, a considerable effort has been devoted to minimizing XPath queries since the efficiency of query processing greatly
depends on the size of the query. Research work in this area can be classified into two categories: constraint-independent
minimization and constraint-dependent minimization. The former minimizes queries in the absence of integrity constraints while
the latter in the presence of them. For a linear path query, which is an XPath query without branching predicates, existing constraint-independent minimization methods are generally
known to be unable to minimize the query without processing the query itself. Most recently, however, by using the DataGuide, a representative structural summary of XML data, a constraint-independent method that minimizes linear path queries in a
top-down fashion has been proposed. Nevertheless, this method can fail to find a minimal query since it minimizes a query
by merely erasing labels from the original query whereas a minimal query could include labels that are not present in the
original query. In this paper, we propose a bottom-up approach called XMin that guarantees finding a minimal query for a given tree pattern query by using the DataGuide without processing the query itself. For the
linear path query, we first show that the sequence of labels occurring in the minimal query is a subsequence of every schema label sequence that matches the original query. Here, the schema label sequence for a node is the sequence of labels from the root of XML
data to the node. We then propose iterative subsequence generation that iteratively generates subsequences from the shortest schema label sequence matching the original query in a bottom-up
fashion and tests query equivalence. Using iterative subsequence generation, we can always find a minimal query and we formally
prove this guarantee. We also propose an extended algorithm that guarantees the minimality for the tree pattern query, which is a linear path query with branching predicates. These methods have been prototyped in a full-fledged object-relational
DBMS. The experimental results using real and synthetic data sets show the practicality of our method. 相似文献
987.
Xiaoying Wu Dimitri Theodoratos Stefanos Souldatos Theodore Dalamagas Timos Sellis 《World Wide Web》2010,13(4):441-474
Finding the occurrences of structural patterns in XML data is a key operation in XML query processing. Existing algorithms
for this operation focus almost exclusively on path patterns or tree patterns. Current applications of XML require querying
of data whose structure is complex or is not fully known to the user, or integrating XML data sources with different structures.
These applications have motivated recently the introduction of query languages that allow a partial specification of path
patterns in a query. In this paper, we consider partial path queries, a generalization of path pattern queries, and we focus
on their efficient evaluation under the indexed streaming evaluation model. Our approach explicitly deals with repeated labels
(that is, multiple occurrences of the same label in a query). We show that partial path queries can be represented as rooted
dags for which a topological ordering of the nodes exists. We present three algorithms for the efficient evaluation of these
queries. The first one exploits a structural summary of data to generate a set of path patterns that together are equivalent
to a partial path query. To evaluate these path patterns, we extend a previous algorithm for path-pattern queries so that
it can work on path patterns with repeated labels. The second one extracts a spanning tree from the query dag, uses a stack-based
algorithm to find the matches of the root-to-leaf paths in the tree, and merge-joins the matches to compute the answer. Finally,
the third one exploits multiple pointers of stack entries and a topological ordering of the query dag to apply a stack-based
holistic technique. We analyze our algorithms and perform extensive experimental evaluations. Our experimental results show
that the holistic algorithm outperforms the other ones. Our approaches are the first ones to efficiently evaluate this class
of queries in the indexed streaming model. 相似文献
988.
An approach for moving object recognition based on BPR and CI 总被引:1,自引:0,他引:1
A recognition and classification method of multiple moving objects in traffic based on the combination of the Biomimetic Pattern
Recognition (BPR) and Choquet Integral (CI) is proposed. The recognition process consists of three stages. At the first stage,
vehicles and pedestrians are detected in video images and the area, the shape and the velocity features are obtained by classical
methods. At the second stage, BPR is used to classify the Zernike moments extracted at the first stage. At the last stage,
CI is then adopted for multi-features fusion based on the output of BPR, and the area and the velocity features obtained at
the first stage to improve the recognition accuracy. Experiment results show that this approach is efficient. 相似文献
989.
One of congress’ goals for 2007 was for 80% of all tax and informational returns to be filed electronically. However, to date
that lofty goal has fallen well short. This research proposes a model of e-filing adoption. To test the model a survey is
administered to 260 participants. The instrument assesses citizen perceptions of trust, risk and optimism bias. Structural
equation modeling is used to evaluate the relationships between these three concepts and intention to use. The results indicate
that trust of the Internet, trust of the e-filer, perceived risk and optimism bias all have an impact on intention to use
e-filing. Implications for practice and research are discussed. 相似文献
990.