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排序方式: 共有64条查询结果,搜索用时 15 毫秒
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Anna-Klara Amler Patrick H. Dinkelborg Domenic Schlauch Jacob Spinnen Stefan Stich Roland Lauster Michael Sittinger Susanne Nahles Max Heiland Lutz Kloke Carsten Rendenbach Benedicta Beck-Broichsitter Tilo Dehne 《International journal of molecular sciences》2021,22(2)
Reconstruction of segmental bone defects by autologous bone grafting is still the standard of care but presents challenges including anatomical availability and potential donor site morbidity. The process of 3D bioprinting, the application of 3D printing for direct fabrication of living tissue, opens new possibilities for highly personalized tissue implants, making it an appealing alternative to autologous bone grafts. One of the most crucial hurdles for the clinical application of 3D bioprinting is the choice of a suitable cell source, which should be minimally invasive, with high osteogenic potential, with fast, easy expansion. In this study, mesenchymal progenitor cells were isolated from clinically relevant human bone biopsy sites (explant cultures from alveolar bone, iliac crest and fibula; bone marrow aspirates; and periosteal bone shaving from the mastoid) and 3D bioprinted using projection-based stereolithography. Printed constructs were cultivated for 28 days and analyzed regarding their osteogenic potential by assessing viability, mineralization, and gene expression. While viability levels of all cell sources were comparable over the course of the cultivation, cells obtained by periosteal bone shaving showed higher mineralization of the print matrix, with gene expression data suggesting advanced osteogenic differentiation. These results indicate that periosteum-derived cells represent a highly promising cell source for translational bioprinting of bone tissue given their superior osteogenic potential as well as their minimally invasive obtainability. 相似文献
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We present a randomized parallel algorithm for constructing the three-dimensional convex hull on a generic p-processor coarse-grained multicomputer with arbitrary interconnection network and n/p local memory per processor, where n/p ≥ p
2+ε
(for some arbitrarily small ε > 0). For any given set of n points in 3-space, the algorithm computes the three-dimensional convex hull, with high probability, in local computation time and O(1) communication phases with at most O(n/p) data sent/received by each processor. That is, with high probability, the algorithm computes the three-dimensional convex
hull of an arbitrary point set in time , where Γ
n,p
denotes the time complexity of one communication phase. The assumption n/p ≥ p
2+ε
implies a coarse-grained, limited parallelism, model which is applicable to most commercially available multiprocessors.
In the terminology of the BSP model, our algorithm requires, with high probability, O(1) supersteps, synchronization period , computation cost , and communication cost O((n/p) g).
Received October 30, 1995, and in revised form April 15, 1996, and in final form September 17, 1996. 相似文献
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Zusammenfassung. Auf der Basis von zwei Verzehrserhebungen – der Berliner Jugendstudie vom Herbst 2002 und der Nationalen Verzehrsstudie vom
Ende der 80er Jahre – und Acrylamidwerten vom Stand Januar 2003 und Oktober 2005 wurde gesch?tzt, wie viel Acrylamid über
die Nahrung aufgenommen worden ist. Ziel dieser Untersuchung war es, die Wirkung des Minimierungskonzepts des Bundesamtes
für Verbraucherschutz und Lebensmittelsicherheit (BVL) in der betrachteten Bev?lkerungsgruppe zu belegen. Auf Basis der Verzehrsmengen
der Berliner Jugendstudie ist eine Verringerung der mittleren t?glichen Acrylamidaufnahme durch den Verzehr der ausgew?hlten
Lebensmittel von 1,08 μg auf 0,81 μg pro kg K?rpergewicht zu beobachten. Das entspricht einer Reduzierung um ca. 25%, die
auf gesunkene Acrylamidwerte der betrachteten Produktgruppen zurückzuführen ist. Etwa identische Ergebnisse bezüglich der
Reduzierung sind zu verzeichnen, wenn die Nationale Verzehrsstudie zugrunde gelegt wird. Auf Basis dieser Daten reduziert
sich die mittlere t?gliche Acrylamidaufnahme pro kg K?rpergewicht von 0,91 μg auf 0,70 μg um ca. 23%.
Eingegangen: 2. August 2006 相似文献
36.
Frank Dehne Quoc T. Pham Ivan Stojmenović 《International journal of parallel programming》1990,19(3):213-224
Consider an×n binary image. Given a directionD, the parallel visibility problem consists of determining for each pixel of the image the portion that is visible (i.e., not obstructed by any other black pixel of the image) in directionD from infinity. A related problem, referred to as point visibility, is to compute for each pixel the portion that is visible from a given pointp. In this paper, we deriveO(logn) time SIMD algorithms for each of these two problems on the hypercube, where one processor is assigned to every pixel of the image. Since the worst case communication distance of two processors in an
2-processor hypercube is 2 logn, it follows that both of the above algorithms are asymptotically optimal.This paper summarizes a preliminary version [Ref. 1] and short note on a possible improvement [Ref. 2] presented at the 1988IFIP WG 10.3. Working Conference on Parallel Processing and 1988Allerton Conference on Communication, Control and Computing, respectively. The first and third authors' research are partially supported by the Natural Sciences and Engineering Research Council of Canada. 相似文献
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Translation separability of sets of polygons 总被引:1,自引:1,他引:0
We consider the problem of separating a set of polygons by a sequence of translations (one such collision-free translation motion for each polygon). If all translations are performed in a common direction the separability problem so obtained has been referred to as the uni-directional separability problem; for different translation directions, the more general multi-directional separability problem arises. The class of such separability problems has been studied previously and arises e.g. in computer graphics and robotics. Existing solutions to the uni-directional problem typically assume the objects to have a certain predetermined shape (e.g., rectangular or convex objects), or to have a direction of separation already available. Here we show how to compute all directions of unidirectional separability for sets of arbitrary simple polygons.The problem of determining whether a set of polygons is multi-directionally separable had been posed by G.T. Toussaint. Here we present an algorithm for solving this problem which, in addition to detecting whether or not the given set is multidirectionally separable, also provides an ordering in which to separate the polygons. In case that the entire set is not multi-directionally separable, the algorithm will find the largest separable subset.Research supported by NSERC under grant No. A9173 and A0392, respectively 相似文献
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