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排序方式: 共有197条查询结果,搜索用时 15 毫秒
71.
Malvindi MA Carbone L Quarta A Tino A Manna L Pellegrino T Tortiglione C 《Small (Weinheim an der Bergstrasse, Germany)》2008,4(10):1747-1755
The development of novel nanomaterials has raised great interest in efforts to evaluate their effect on biological systems, ranging from single cells to whole animals. In particular, there exists an open question regarding whether nanoparticles per se can elicit biological responses, which could interfere with the phenomena they are intended to measure. Here it is reported that challenging the small cnidaria Hydra vulgaris in vivo with rod-shaped semiconductor nanoparticles, also known as quantum rods (QRs), results in an unexpected tentacle-writhing behavior, which is Ca(2+) dependent and relies on the presence of tentacle neurons. Due to the absence of surface functionalization of the QRs with specific ligands, and considering that spherical nanoparticles with same composition as the QRs fail to induce any in vivo behavior on the same experimental model, it is suggested that unique shape-tunable electrical properties of the QRs may account for the neuronal stimulation. This model system may represent a widely applicable tool for screening neuronal response to nanoparticles in vivo. 相似文献
72.
73.
Tommaso Addabbo Davide De Caro Ada Fort Nicola Petra Santina Rocchi Valerio Vignoli 《International Journal of Circuit Theory and Applications》2012,40(1):1-14
In this paper we discuss the efficient implementation of pseudochaotic piecewise linear maps with high digitization accuracies, taking the R'enyi chaotic map as a reference. The proposed digital architectures are based on a novel algorithmic approach that uses carry save adders for the nonlinear arithmetic modular calculations arising when computing piecewise linear maps with a finite precision. As a result, the system can be implemented by digital circuits obtaining high throughputs, which are not dependent on the digital resolution while involving a hardware complexity linearly proportional to the number of bits used for representing the discretized state. The proposed solutions result to be particularly suitable for the implementation of pseudorandom number generators based on pseudochaos, or for the definition of efficient digital blocks that can be integrated in most of the pseudochaotic cyphers proposed in the literature. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
74.
Magnetic resonance imaging (MRI) is the imaging tool of choice in the evaluation of prostate cancer. The main applications
of MR imaging in the management of prostate cancer are: (1) to guide targeted biopsy when prostate cancer is clinically suspected
and previous ultrasound-guided biopsy results are negative; (2) to localize and stage prostate cancer and provide a roadmap
for treatment planning; and (3) to detect residual or locally recurrent cancer after treatment. Other MR techniques such as
proton MR spectroscopic imaging (MRSI), diffusion-weighted imaging (DWI), and contrast-enhanced MRI (CE-MRI) complement conventional
MR imaging by providing metabolic and functional information that can improve the accuracy of prostate cancer detection and
characterization. In everyday clinical practice, and to account for patient comfort, MR imaging studies are limited to 1 h.
To obtain consistently high-quality images, a well-designed protocol is necessary. Routine MR imaging can be supplemented
by other MR techniques such as MRSI, DWI or CE-MRI depending on the expertise available and the clinical questions that need
to be answered. This review summarizes the role of MR imaging in the management of prostate cancer and describes practical
approaches to implementing anatomic, metabolic and functional MR imaging techniques in the clinic. 相似文献
75.
The focus of this study was to assess the hygienic standards of 44 foodservice facilities located in three Italian International Airports (with an output ranging from 100 to 800 meals a day), by monitoring the microbiological quality and safety of foods ready for consumption (n = 773), food contact surfaces (n = 302), and food handlers (n = 287). The hygienic standard of surfaces was sufficiently high. Only 7.9% of surfaces did not conform with advisory standards in terms of total coliforms, and 2.6% were found to be contaminated with Enterococcus spp. at ≥1.0 log10 CFU/cm2. The hygienic standard of washed and disinfected hands of food workers was not adequately high: the total bacterial count and coagulase positive Staphylococci exceeded the satisfactory limit in 8.4% and 3.5% of cases, respectively. The microbial analysis of foods examined showed an absence of Listeria monocytogenes and Salmonella spp. Food sample analyses highlighted a percentage of samples that did not conform to microbial reference standards: Staphylococcus aureus non-conforming percentages ranged from 2.3% for “fully cooked food” to 9.2% for “raw fruit and vegetables”; Escherichia coli, from 0.0% for “raw fruit and vegetables” to 6.1% for “cooked and uncooked foods”; total coliforms from 14.3% for “fully cooked food” to 79.8% for “cooked and uncooked food”. In conclusion, the results suggest that more effort is needed in the application of HACCP principles. In order to prevent travel-related foodborne infections, various changes in the timing of food preparation and holding temperatures are needed, together with further training of food handlers. 相似文献
76.
并行工程中的模糊知识(信息)协同方法研究 总被引:5,自引:0,他引:5
在文献[1]的基础上进一步讨论了基于模糊集理论的知识协同处理算法。文中提出的算法体现了权威性和民主性相结合的原则,并对提出的算法的灵敏度进行了理论上的分析。通过实例分析,提出的算法具有较强的实用性和良好的效果,易为各个知识源所接受。 相似文献
77.
The complexity of the clinical, educational, and research situations confronting the health care provider suggests the need for collaboration among professionals. Psychologists, advanced practice nurses, and physicians will have to interface continuously to provide accessible quality care at an affordable price. Intra-, inter-, and multidisciplinary types of collaboration are defined, and characteristics of collaborative clinical, educational, and research endeavors are noted. A community partnership for prenatal care, a rural interdisciplinary training program, and a Department of Defense psychopharmacology training project are described. (0 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
78.
Mining top-K frequent itemsets from data streams 总被引:1,自引:0,他引:1
Frequent pattern mining on data streams is of interest recently. However, it is not easy for users to determine a proper frequency
threshold. It is more reasonable to ask users to set a bound on the result size. We study the problem of mining top K frequent itemsets in data streams. We introduce a method based on the Chernoff bound with a guarantee of the output quality
and also a bound on the memory usage. We also propose an algorithm based on the Lossy Counting Algorithm. In most of the experiments
of the two proposed algorithms, we obtain perfect solutions and the memory space occupied by our algorithms is very small.
Besides, we also propose the adapted approach of these two algorithms in order to handle the case when we are interested in
mining the data in a sliding window. The experiments show that the results are accurate.
相似文献
Ada Wai-Chee FuEmail: |
79.
A common problem in production planning is to sequence a series of tasks so as to meet demand while satisfying operational constraints. This problem can be challenging to solve in its own right. It becomes even more challenging when higher-level decisions are also taken into account. For example, determining which shifts to operate clearly impacts how tasks are then scheduled; additionally, reducing the number of shifts that must be operated can have great cost benefits. Integrating the shift-selection and task-sequencing decisions can greatly impact tractability, however, traditional mathematical programming approaches often failing to converge in reasonable run times. Instead, we develop an approach that embeds mathematical programming, as a mechanism for solving simpler feasibility problems, within a larger search-based algorithm that leverages dominance to achieve substantial pruning. In this paper, we introduce the Shift-Selection and Task Sequencing problem (SS-TS), develop the Test-and-Prune algorithm (T&P), and present computational experiments based on a real-world problem in automotive stamping to demonstrate its effectiveness. In particular, we are able to solve to provable optimality, in very short run times, a number of problem instances that could not be solved through traditional integer programming methods. 相似文献
80.
When a data file is replicated at more than one site, it is of interest to detect corruption by comparing the multiple copies. In order to reduce the amount of messaging for large files, techniques based on page signatures and combined signatures have been explored. However, for 3 or more sites, the known methods assume that the number of corrupted page copies is at most M/2 – 1, where M is the number of sites. This is a pessimistic assumption which is unrealistic. In this paper, this assumption is replaced by another assumption which is shown to be reasonable. Based on this assumption, and based on a finer model of the system, three distributed algorithms are derived, which can either improve the performance or provide more tolerance to corruptions compared to previous methods. As in some previous work, the amount of signature transmission in the algorithms varies according to the number and patterns of page copy corruptions that actually occur, and two of the algorithms achieve the optimal amount of signature transmission when no failure occurs. 相似文献