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排序方式: 共有2364条查询结果,搜索用时 15 毫秒
21.
B Preckel G Kojda W Schlack D Ebel K Kottenberg E Noack V Th?mer 《Canadian Metallurgical Quarterly》1997,96(8):2675-2682
Facial fractures may portend intracranial and skullbase injury and may lead to rapid compromise of the airway. Primary care physicians may provide emergency care for patients who have sustained facial trauma. After immediate resuscitation and stabilization, management of facial fractures requires knowledge of the anatomy, rapid treatment methods and identification of potential associated injuries for each type of facial fracture. Differentiation between the life-threatening aspects of these injuries and the less urgent, but more apparent, facial injuries will lessen the risk of complications such as bleeding, meningitis and asphyxia. Knowledge of the anatomy of the facial skeleton and of the potential injuries associated with each of the various types of facial fractures will facilitate effective management decisions. Consultation should be sought when functional features are involved or when the injury threatens to produce future cosmetic anomalies. 相似文献
22.
The liver microsomal Δ9 and Δ6 desaturase activities have been studied in rats with carbon tetrachloride-induced hepatitis. Immediately after poisoning,
significant decreases were observed for both types of desaturase activity. However, recovery kinetics were slower for the
Δ6 desaturase than for the Δ9 desaturase. The activities of NADH-ferricyanide and NADH-cytochrome C reductases, proteins involved in the electron transfers
associated with microsomal desaturation, were also measured. There was a fall in both activities after poisoning, but this
decrease was less than that of the desaturase activities. 相似文献
23.
Production and Debittering of Edible Oil and a Protein Concentrate from Seeds of Lupinus mutabilis Lupine oil was produced from seeds of L. mutabilis using an extraction and refining process of soya oil. The refining included a step of debittering by washing with diluted acids. This decreased the alkaloid content from 0.14 % in the raw oil to 5 ppm in the endproduct, a content of rest alkaloids, which can be considered as unobjectionable. The oil alkaloids are not identical with those of the seeds. While in seeds Lupanin is the main alkaloid fraction, in the oil 13-Hydroxylupanin and N-Methyl angustofolin are dominant. The raw oil contained 800 ppm γ-Tocopherol 39 ppm α-Tocopherol. During the refining process the Tocopherol content decreased from about 840 ppm to 530 ppm total Tocopherol in the endproduct. The oil-cake contained about 4 % alkaloids. With aqueous alcohol (70 %?90 % ethanol) was debittered to a protein concentrate, which contained 73% protein and 0.06% rest alkaloids. By changing the pH value of the debittering medium both in the acid (pH 5) and alkaline (pH 9) range the alkaloid extraction could be improved and the loses of protein could be diminished. Qualitatively the alkaloid pattern of the protein concentrate was similar to that of seeds, although the hydroxylupanin fraction increased from 32.7% of total alkaloids before the debittering to 42.3% in the debittered concentrate. This is advantageous because the toxicity of hydroxylupanin is only about 1/10 of that of Lupanin. 相似文献
24.
Arkadev Chattopadhyay Ricard Gavaldà Kristoffer Arnsfelt Hansen Denis Thérien 《Theory of Computing Systems》2014,55(2):404-420
Boolean functions that have constant degree polynomial representation over a fixed finite ring form a natural and strict subclass of the complexity class ACC0. They are also precisely the functions computable efficiently by programs over fixed and finite nilpotent groups. This class is not known to be learnable in any reasonable learning model. In this paper, we provide a deterministic polynomial time algorithm for learning Boolean functions represented by polynomials of constant degree over arbitrary finite rings from membership queries, with the additional constraint that each variable in the target polynomial appears in a constant number of monomials. Our algorithm extends to superconstant but low degree polynomials and still runs in quasipolynomial time. 相似文献
25.
Dielectrophoresis (DEP) allows to moving neutral or charged particles in liquids by supplying a non-uniform electric field. When using alternating current and insulated electrodes, this is possible in conducting media such as aqueous solutions. However, relatively high field strength is required that is discussed to induce also an undesired Joule heating effect. In this paper, we demonstrate boundary conditions for avoiding this side effect and suggest a novel design of an interdigitated electrode (IDE) configuration to reduce the power consumption. Numerical simulation using OpenFOAM demonstrated that, when replacing conventional plate IDE by cylindrical micro-IDE in microchannel systems, the dielectrophoretic force field, i.e., the electric field gradient squared, becomes stronger and more homogeneously distributed along the electrodes array. Also the resulting particle DEP velocities were highest for the cylindrical IDE. The simulations were experimentally confirmed by measuring velocity of resin particle located at the subsurface of demineralized water. Surprisingly the fluid flow induced by electrothermal effect turned out to be negligible in microchannels when compared to the DEP effect and becomes dominant only for distances between particle and IDE larger than 6,000 μm. The well-agreed experimental and simulation results allow for predicting particle motion. This can be expected to pave the way for designing DEP microchannel separators with high throughput and low energy consumption. 相似文献
26.
This work presents a method for efficiently simplifying the pressure projection step in a liquid simulation. We first devise a straightforward dimension reduction technique that dramatically reduces the cost of solving the pressure projection. Next, we introduce a novel change of basis that satisfies free‐surface boundary conditions exactly, regardless of the accuracy of the pressure solve. When combined, these ideas greatly reduce the computational complexity of the pressure solve without compromising free surface boundary conditions at the highest level of detail. Our techniques are easy to parallelize, and they effectively eliminate the computational bottleneck for large liquid simulations. 相似文献
27.
A.?Konstantinidis Th.?TsiatsosEmail author A.?Pomportsis 《Multimedia Tools and Applications》2009,44(2):279-304
E-learning systems have gone through a radical change from the initial text-based environments to more stimulating multimedia
systems. Such systems are Collaborative Virtual Environments, which could be used in order to support collaborative e-learning
scenarios. The main aim of this paper is to aid educational designers in selecting, designing and evaluating three dimensional
collaborative virtual environments in order to gain the pedagogical benefits of Computer Supported Collaborative Learning.
Therefore, this paper initially discusses the potential of three dimensional networked virtual environments for supporting
collaborative learning. Furthermore, based on a two-step platform selection process this paper (a) presents and compares three
dimensional multi-user virtual environments for supporting collaborative learning and (b) validates the most promising solution
against a set of design principles for educational virtual environments. According to these principles, an educational environment
has been implemented on top of the selected platform in order to support collaborative e-learning scenarios. The design of
this environment is also presented. In addition, this paper presents the results of three small scale studies carried out
in a tertiary education department, to assess the educational environment. This environment has been evaluated based on a
hybrid evaluation methodology for uncovering usability problems, collecting further requirements for additional functionality
to support collaborative virtual learning environments, and determining the appropriateness of different kinds of learning
scenarios.
相似文献
A. PomportsisEmail: |
28.
We propose a new fluid control technique that uses scale-dependent force control to preserve small-scale fluid detail. Control particles define local force fields and can be generated automatically from either a physical simulation or a sequence of target shapes. We use a multi-scale decomposition of the velocity field and apply control forces only to the coarse-scale components of the flow. Small-scale detail is thus preserved in a natural way avoiding the artificial viscosity often introduced by force-based control methods. We demonstrate the effectiveness of our method for both Lagrangian and Eulerian fluid simulation environments. 相似文献
29.
This study examines the effect of training procedures, as measured by the results of a test, on the level of assimilation of a new safety programme in 80 Quebec companies. The Workplace Hazardous Materials Information System (WHMIS) was introduced in the province in 1989. The bipartite safety association representing the manufacturers of transportation equipment and machinery offered two types of WHMIS training services to their members: (a) 4 h employee training courses, and (b) two-day trainer training courses. Companies were free to choose from these and other services to comply with the WHMIS training requirements. A test was issued to a stratified sample of 862 employees approximately one year after the training. On average, the scores were best in plants having employees trained directly by experts from the safety association (type a). The training of internal trainers for companies produced slightly inferior learning results (type b). 相似文献
30.
Denis Thérien 《Computational Complexity》1994,4(4):383-388
Algebraic techniques are used to prove that any circuit constructed with MOD
q
gates that computes the AND function must use (n) gates at the first level. The best bound previously known to be valid for arbitraryq was (logn). 相似文献