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91.
The more extreme conditions the vehicle is exposed to, the sooner it wears out and deteriorates. In order to determine the forces affecting the lifespan of vehicles we need to know the environmental conditions eliciting these forces.This research aims at elaborating and testing a method which can help to conduct a comparative analysis of forces acting on towed vehicles used in different terrain conditions. Excitation forces acting on a vehicle being towed across terrain cause vibrations which lead to wear and structural deterioration. The rate of deterioration depends on the activating forces resulting from the road profile geometry and the dynamic properties of the vehicle. A knowledge of the relationship between the towed vehicle and the terrain profile will enable the design of an artificial road profile for fatigue testing with which similar stresses arise as during normal use. With the developed comparative method, a connection can be established between stochastic road profiles and road profiles containing artificially built obstacles. 相似文献
92.
Using a tool-energy of d-dimensional signal sequences taking values 1 or -1, we have completely solved an interesting discrete mathematical problem on d-dimensional symmetric weighted median filters, i.e., when a d-dimensional symmetric weighted median filter is applied iteratively to a real signal sequence, then the limit of the iterates with even index as well as the limit of the iterates with odd index both converge. 相似文献
93.
94.
John R. Stembridge 《Journal of Combinatorial Theory, Series A》2007,114(7):1220-1237
We introduce the concept of irreducible circuits. In a vector arrangement Φ, these are configurations consisting of one vector α∈Φ in the positive linear span of an independent set Δ⊂Φ such that no proper subset of Δ has any member of Φ−Δ in its positive linear span. We show that the oriented matroid of any centrally symmetric vector arrangement is constructively determined by its irreducible circuits, and classify the irreducible circuits in root systems. 相似文献
95.
96.
《Journal of carbohydrate chemistry》2013,32(7-8):765-779
The conformational behavior of the capsular polysaccharide obtained from a fast‐growing soybean‐nodulating rhizobia (strain B33) isolated from Xinjiang Autonomous Region (Eastern China) has been analyzed by NMR and molecular mechanics simulations. This polysaccharide has the repeating unit →6)‐4‐O‐Me‐α‐d‐Glcp‐(1→4)‐3‐O‐Me‐β‐d‐GlcpA‐(1→. The NMR results indicate that the α‐(1→4) linkage may adopt a variety of conformations, and that at least two of the resulting minima must exist in solution. NOE data agree with an 85:10:5 ratio for the lowest‐energy conformations. In the case of the β‐(1→6) linkage, NMR indicates that the rotamer gg is highly populated. Experimental and calculated NOE intensities match well when the global energy minimum conformation for this linkage has exclusively the gg orientation. The influence of the adjacent methyl group on the glycosyloxymethyl population has been evaluated by simulation of a disaccharide without this group. A relative destabilization of gt rotamer has been found. Long chains have been simulated using a Metropolis algorithm at different ratios of the gg and gt rotamers in the glucose moiety. It was observed that the increase in population of the gt rotamer yielded more close contacts in the chain. 相似文献
97.
98.
Jovana D?uni? Miodrag S. Petkovi?Ljiljana D. Petkovi? 《Applied mathematics and computation》2011,217(19):7612-7619
Using an interactive approach which combines symbolic computation and Taylor’s series, a wide family of three-point iterative methods for solving nonlinear equations is constructed. These methods use two suitable parametric functions at the second and third step and reach the eighth order of convergence consuming only four function evaluations per iteration. This means that the proposed family supports the Kung-Traub hypothesis (1974) on the upper bound 2m of the order of multipoint methods based on m + 1 function evaluations, providing very high computational efficiency. Different methods are obtained by taking specific parametric functions. The presented numerical examples demonstrate exceptional convergence speed with only few function evaluations. 相似文献
99.
Root canal treatment is performed to remove the bacteria proliferating in the root canals of a tooth. Many conventional root canal irrigation methods use an instrument inserted into the root canals. However, bacteria removal is often incomplete in the apical region of the root canal, and the treatment carries clinical risks, such as instrument fracture and extrusion of irrigation liquid through the canal apex. We here suggest a novel, remotely generated high-intensity ultrasound irrigation system that exhibits better irrigation performance and a reduced clinical risk. Our device employs powerful ultrasonic waves generated by a transducer placed outside a target tooth. The generated ultrasonic waves are guided to travel into the root canals. In the root canals of the target tooth, acoustic cavitation occurs, and vapor bubbles are created. The dynamic motions of vapor bubbles create remarkable cleaning effects. Using root canal models, we tested the cleaning performance of the proposed system and compared it with other conventional irrigation methods. The results revealed that biofilm in the apical region of the root canal models can be removed exclusively using the proposed system, thus demonstrating an improvement in cleaning performance. We also measured pressure at the apex of the root canals of an extracted tooth while operating the proposed system. Our system exhibited a smaller pressure compared to the syringe irrigation method, thus suggesting a reduced risk of apical extrusion of the irrigation liquid. Since the proposed system operates without inserting instruments into the root canal, it can clean multiple root canals in a tooth simultaneously with a single treatment. The proposed device would be a breakthrough in root canal treatment in terms of irrigation performance, clinical safety, and ease of treatment. 相似文献
100.
We investigate the imaginary cone in hyperbolic Coxeter systems in order to show that any Coxeter system contains universal reflection subgroups of arbitrarily large rank. Furthermore, in the hyperbolic case, the positive spans of the simple roots of the universal reflection subgroups are shown to approximate the imaginary cone (using an appropriate topology on the set of roots), answering a question due to Dyer [9] in the special case of hyperbolic Coxeter systems. Finally, we discuss growth in Coxeter systems and utilize the previous results to extend the results of [16] regarding exponential growth in parabolic quotients in Coxeter groups. 相似文献