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1.
2.
3.
Given a digraph (or an undirected graph) G=(V,E) with a set V of vertices v with nonnegative real costs w(v), and a set E of edges and a positive integer k, we deal with the problem of finding a minimum cost subset SV such that, for each vertex vV−S, there are k vertex-disjoint paths from S to v. In this paper, we show that the problem can be solved by a greedy algorithm in
time in a digraph (or in
time in an undirected graph), where n=|V| and m=|E|. Based on this, given a digraph and two integers k and ℓ, we also give a polynomial time algorithm for finding a minimum cost subset SV such that for each vertex vV−S, there are k vertex-disjoint paths from S to v as well as ℓ vertex-disjoint paths from v to S. 相似文献
4.
We report current-induced magnetization reversal in a ferromagnetic semiconductor-based magnetic tunnel junction (Ga,Mn)As/AlAs/(Ga,Mn)As prepared by molecular beam epitaxy on a p-GaAs(001) substrate. A change in magneto-resistance that is asymmetric with respect to the current direction is found with the excitation current of 106 A/cm2. Contributions of both unpolarized and spin-polarized components are examined, and we conclude that the partial magnetization reversal occurs in the (Ga,Mn)As layer having smaller magnetization with the spin-polarized tunneling current of 105 A/cm2. 相似文献
5.
Suppose that some particular link in the Internet is currently
congested.
A natural solution is to try to make packets bypass that link.
This can be done by increasing the cost of that link intentionally,
say from a
1 to a
2, since the Internet uses shortest-path
routing. Unfortunately, however, this often causes temporary loops
for packet traveling, called routing loops. In this paper
we show that routing loops can be avoided by increasing the cost
of the link not directly from a
1 to a
2 but through an
intermediate value, a
3, i.e., from a
1 to a
3 and then
to a
2.
We may need several
intermediate values.
We show that in this case
the greedy strategy,
namely, raising the cost as much as possible in each step,
is optimal. 相似文献
6.
Grimshaw Andrew Morgan Mark Merrill Duane Kishimoto Hiro Savva Andreas Snelling David Smith Chris Berry Dave 《Computer》2009,42(2):27-34
To expand the use of distributed computer infrastructures as well as facilitate grid interoperability, OGSA has developed standards and specifications that address a range of scenarios, including high-throughput computing, federated data management, and service mobility. 相似文献
7.
Takahashi H Masuda K Ando T Kobayashi T Honda H 《Journal of Bioscience and Bioengineering》2004,98(3):193-199
Gene expression profiling data from DNA microarray were analyzed using the fuzzy neural network (FNN) modeling method for predicting the distant metastases of breast cancer. The best model consisting of five genes was able to predict metastases of breast cancer with 94% accuracy. Furthermore, 100% accuracy was achieved by majoritarian decision using only 25 genes from five noninferior models which were constructed independently. From the constructed model, gene expression rules, which may cause distant metastases, were explicitly extracted and 60% of the metastases cases could be explained by this rule. The FNN modeling method described in this paper enables precise extraction of significant biological markers affecting prognosis without prior knowledge. 相似文献
8.
Shingo Hirose Akihiro Yoshida Masaaki Yamaura Nobuo Kano Hiro Munekata 《Journal of Materials Science: Materials in Electronics》2000,11(1):7-10
We demonstrate a method for successfully controlling carbon incorporation in AlAs layers grown by atomic layer epitaxy (ALE) using various GaAs substrates with different orientations. The number of alkyl radicals attached to an Al atom at the surface, which is a main factor in carbon incorporation, can be intentionally controlled by changing substrate orientation. We found that the carbon incorporation in ALE-AlAs using the (3 1 1)B surface is 2 x 1017,cm-3, which is the lowest value ever reported for ALE-AlAs that satisfies one-monolayer self-limiting growth conditions. 相似文献
9.
Tiesheng Li Shuji Okada Hirohito Umezawa Hitoshi Kasai Hachiro Nakanishi Satya S. Talwar Tatsumi Kimura Hiro Matsuda 《Polymer Bulletin》2006,57(5):737-746
Summary 1,4-Bis(3-quinolyl)-1,3-butadiyne (DQ) is known to be polymerized in solid state to give the corresponding polydiacetylene.
However, the polymer yield of DQ bulk crystals is low. Thus, we prepared several types of DQ crystals by different procedures
to find the reason for the low polymer yield. We found three modifications of DQ crystals and they were evaluated by spectroscopic
measurements and X-ray diffraction. DQ bulk crystals (Crystal I) and thermally grown DQ crystals on Crystal I (Crystal II)
have the same structure classified to Type A, which gives regular polydiacetylene structure in low polymer yields. DQ crystals
grown on glass plates by sublimation (Crystal III) belong to the second modification of Type B. DQ nanocrystals prepared by
the reprecipitation method (Crystal IV) are Type B, and thermally grown DQ crystals on nanocrystals (Crystal V) are Type C.
Crystals of Types B and C could be polymerized in low yields without showing excitonic absorption of polydiacetylene indicating
irregular polymerization other than 1,4-addition. For crystals of Type A, we found that the 1,4-addition polymerization proceeded
only in near-surface portions of the crystals. It can be plausibly explained that mobile monomers in the near-surface portion
are only able to take part in their polymerization, resulting in low polymer conversion. 相似文献
10.
OBJECTIVE: The Alcohol Use Disorders Identification Test (AUDIT) is an instrument designed to identify hazardous drinkers, harmful drinkers and alchoholics. It was translated into Japanese using the WHOQOL method. The concurrent validity and reliability of the Japanese version of AUDIT were evaluated in a complete health examination. The instrument was also compared with the CAGE questionnaire. METHOD: The subjects were 93 applicants attending for health checks in a human dry dock. They completed self-report questionnaires containing the Core AUDIT and CAGE. and underwent a semi-structured interview conducted by a professional physician. RESULT: From the semi-structured interview, it was determined that 23 of the subjects were problem drinkers and 10 were alcoholics. Analyses indicated that the Core AUDIT was sufficiently sensitive and specific for discriminating problem drinkers and alcoholics. Core AUDIT was also superior to CAGE for discriminating problem drinkers from non-problem drinkers, as well as identifying alcoholics. CONCLUSION: The data suggest that the Japanese version of AUDIT is useful for early detection of hazardous or harmful drinkers. 相似文献