全文获取类型
收费全文 | 2284篇 |
免费 | 103篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 23篇 |
综合类 | 3篇 |
化学工业 | 579篇 |
金属工艺 | 33篇 |
机械仪表 | 47篇 |
建筑科学 | 80篇 |
矿业工程 | 5篇 |
能源动力 | 96篇 |
轻工业 | 250篇 |
水利工程 | 37篇 |
石油天然气 | 10篇 |
无线电 | 173篇 |
一般工业技术 | 327篇 |
冶金工业 | 233篇 |
原子能技术 | 14篇 |
自动化技术 | 485篇 |
出版年
2024年 | 5篇 |
2023年 | 33篇 |
2022年 | 92篇 |
2021年 | 116篇 |
2020年 | 78篇 |
2019年 | 65篇 |
2018年 | 69篇 |
2017年 | 75篇 |
2016年 | 79篇 |
2015年 | 79篇 |
2014年 | 66篇 |
2013年 | 152篇 |
2012年 | 155篇 |
2011年 | 158篇 |
2010年 | 106篇 |
2009年 | 113篇 |
2008年 | 99篇 |
2007年 | 101篇 |
2006年 | 92篇 |
2005年 | 77篇 |
2004年 | 63篇 |
2003年 | 42篇 |
2002年 | 52篇 |
2001年 | 28篇 |
2000年 | 16篇 |
1999年 | 27篇 |
1998年 | 56篇 |
1997年 | 39篇 |
1996年 | 23篇 |
1995年 | 18篇 |
1994年 | 17篇 |
1993年 | 18篇 |
1992年 | 9篇 |
1991年 | 14篇 |
1990年 | 8篇 |
1989年 | 19篇 |
1988年 | 8篇 |
1987年 | 14篇 |
1986年 | 12篇 |
1985年 | 7篇 |
1984年 | 11篇 |
1983年 | 10篇 |
1982年 | 4篇 |
1981年 | 7篇 |
1980年 | 15篇 |
1979年 | 4篇 |
1976年 | 9篇 |
1975年 | 4篇 |
1974年 | 7篇 |
1972年 | 4篇 |
排序方式: 共有2395条查询结果,搜索用时 15 毫秒
41.
Roman Krepki Benjamin Blankertz Gabriel Curio Klaus-Robert Müller 《Multimedia Tools and Applications》2007,33(1):73-90
The investigation of innovative Human-Computer Interfaces (HCI) provides a challenge for future multimedia research and development.
Brain-Computer Interfaces (BCI) exploit the ability of human communication and control bypassing the classical neuromuscular
communication channels. In general, BCIs offer a possibility of communication for people with severe neuromuscular disorders,
such as Amyotrophic Lateral Sclerosis (ALS) or spinal cord injury. Beyond medical applications, a BCI conjunction with exciting
multimedia applications, e.g., a dexterity game, could define a new level of control possibilities also for healthy customers
decoding information directly from the user’s brain, as reflected in electroencephalographic (EEG) signals which are recorded
non-invasively from user’s scalp. This contribution introduces the Berlin Brain–Computer Interface (BBCI) and presents setups
where the user is provided with intuitive control strategies in plausible gaming applications that use biofeedback. Yet at
its beginning, BBCI thus adds a new dimension in multimedia research by offering the user an additional and independent communication
channel based on brain activity only. First successful experiments already yielded inspiring proofs-of-concept. A diversity
of multimedia application models, say computer games, and their specific intuitive control strategies, as well as various
Virtual Reality (VR) scenarios are now open for BCI research aiming at a further speed up of user adaptation and increase
of learning success and transfer bit rates.
相似文献
Klaus-Robert MüllerEmail: |
42.
Starting from the idea of determinism in membrane systems, we introduce a language generating device consisting of morphisms
placed in the nodes of a tree. Initial strings are given in the leaves; by iteratively applying the morphisms to them, we
produce new strings, which are collected in the root of the tree. Such a device is called a tree-system of morphisms (in short, a T system). We investigate here the power of T systems, both in the extended (a terminal alphabet is considered
and only strings over it are accepted) and non-extended case, mainly in comparison with classes of languages in Lindenmayer
hierarchy.
Received: 8 February 2001 / 18 September 2001 相似文献
43.
In this paper, we introduce two algorithms to address the two-echelon capacitated location-routing problem (2E-CLRP). We introduce a branch-and-cut algorithm based on the solution of a new two-index vehicle-flow formulation, which is strengthened with several families of valid inequalities. We also propose an adaptive large-neighbourhood search (ALNS) meta-heuristic with the objective of finding good-quality solutions quickly. The computational results on a large set of instances from the literature show that the ALNS outperforms existing heuristics. Furthermore, the branch-and-cut method provides tight lower bounds and is able to solve small- and medium-size instances to optimality within reasonable computing times. 相似文献
44.
von Hippel William; von Hippel Courtney; Conway Leanne; Preacher Kristopher J.; Schooler Jonathan W.; Radvansky Gabriel A. 《Canadian Metallurgical Quarterly》2005,89(1):22
Four experiments tested the hypothesis that people who are concerned with impression management cope with stereotype threat through denial. Consistent with this hypothesis, temporary employees threatened by a stereotype of incompetence (Study 1) and hostel-dwelling older adults (Study 2) were more likely to deny incompetence if they were high in impression management. African Americans (Study 3) showed a similar pattern of denying cognitive incompetence, which emerged primarily when they were interviewed by a White experimenter and had attended a predominantly Black high school. In Study 4, White students who expected to take an IQ test and were threatened by a stereotype of being less intelligent than Asians were more likely to deny that intelligence is important if they were high in impression management. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
45.
Rainer Keller Edgar Gabriel Bettina Krammer Matthias S. Müller Michael M. Resch 《Journal of Grid Computing》2003,1(2):133-149
The message passing interface (MPI) is a standard used by many parallel scientific applications. It offers the advantage of a smoother migration path for porting applications from high performance computing systems to the Grid. In this paper Grid-enabled tools and libraries for developing MPI applications are presented. The first is MARMOT, a tool that checks the adherence of an application to the MPI standard. The second is PACX-MPI, an implementation of the MPI standard optimized for Grid environments. Besides the efficient development of the program, an optimal execution is of paramount importance for most scientific applications. We therefore discuss not only performance on the level of the MPI library, but also several application specific optimizations, e.g., for a sparse, parallel equation solver and an RNA folding code, like latency hiding, prefetching, caching and topology-aware algorithms. 相似文献
46.
In this paper the conjugate fluid flow and energy transport problem (involving conduction-convection-radiation heat transfer) resulting from the Czochralski crystal growth process is analysed. The solidifying material is treated as a pure and semitransparent substance with material properties depending neither on temperature nor on the wavelength. The solution of the problem is obtained iteratively using two computer codes: FLUENT, a commercial CFD package, and BEM-based in-house code capable of analysing the radiative heat transfer in the entire computational domain.Obtained results not only show velocity field and temperature distribution within the bodies under consideration but also demonstrate the influence of thermal radiation on these quantities. 相似文献
47.
A physical model of interfacial waves in annular two-phase flow was studied in both microgravity and normal gravity. The wave
structure was obtained for local film thickness and velocity measurements using a conductance probe technique. It was found
that the wave height, and not its width, is strongly affected by changing the gravity level. In fact, the wave height in normal
gravity is more than twice that in microgravity. Using an analogous approach to a turbulent, single-phase flow in a rough
tube, a preliminary mathematical model was proposed to calculate the wave amplitude. The model fits well with the experimental
data and shows that the wave height in normal gravity is approximately 1.7 times the combined thickness of the viscous sublayer
and transition zones in the turbulent gas stream. The wave height in microgravity was estimated to be approximately 80% of
the total thickness. 相似文献
48.
David Gabriel Huub H. J. Cox Marc A. Deshusses 《Canadian Metallurgical Quarterly》2004,130(10):1110-1117
Until recently, biological treatment of odors in biofilters or biotrickling filters was thought to require a longer gas contact time than chemical scrubbing, hence bioreactors for air treatment required a larger footprint. This paper discusses the conversion of chemical scrubbers to biological trickling filters. Initially, research was conducted with a laboratory-scale biotrickling filter. An effective open-pore polyurethane packing material was identified and H2S biotreatment performance was quantified. Key technical issues in determining the general suitability of converting wet scrubbers to biotrickling filters were identified, and a generic ten-step conversion procedure was developed. Following the laboratory research, five full-scale chemical scrubbers treating odorous air at the Sanitation District of Orange County, Calif., were converted to biotrickling filters. The original airflow rate was maintained, resulting in a gas contact time as low as 1.6–3.1?s. The converted biotrickling filters demonstrated an excellent capability for treating high H2S concentrations to concentrations below regulatory limits. This study shows outstanding potential for converting chemical scrubbers to biotrickling filters at publicly owned treatment works. 相似文献
49.
Anca-Maria Istrate-Ofieru Elena-Iuliana-Anamaria Berbecaru George-Lucian Zoril Gabriela-Camelia Rou Laureniu Mihai Dîr Cristina Maria Comnescu Roxana Cristina Drguin Dan Ruican Rodica Daniela Nagy Dominic Gabriel Iliescu Laureniu Mogoant Daniel Pirici 《International journal of molecular sciences》2022,23(10)
Ectopic endometrial epithelium associates a wide spectrum of symptomatology. Their evolution can be influenced by inflammatory and vascular changes, that affect not only the structure and cell proliferation rate, but also symptoms. This prospective study involved tissue samples from surgically treated patients, stained using classical histotechniques and immunohistochemistry. We assessed ectopic endometrial glands (CK7+, CK20−), adjacent blood vessels (CD34+), estrogen/progesterone hormone receptors (ER+, PR+), inflammatory cells (CD3+, CD20+, CD68+, Tryptase+), rate of inflammatory cells (Ki67+) and oncoproteins (BCL2+, PTEN+, p53+) involved in the development of endometriosis/adenomyosis. A CK7+/CK20− expression profile was present in the ectopic epithelium and differentiated it from digestive metastases. ER+/PR+ were present in all cases analyzed. We found an increased vascularity (CD34+) in the areas with abdominal endometriosis and CD3+−:T-lymphocytes, CD20+−:B-lymphocytes, CD68+:macrophages, and Tryptase+: mastocytes were abundant, especially in cases with adenomyosis as a marker of proinflammatory microenvironment. In addition, we found a significantly higher division index-(Ki67+) in the areas with adenomyosis, and inactivation of tumor suppressor genes-p53+ in areas with neoplastic changes. The inflammatory/vascular/hormonal mechanisms trigger endometriosis progression and neoplastic changes increasing local pain. Furthermore, they may represent future therapeutic targets. Simultaneous-multiple immunohistochemical labelling represents a valuable technique for rapidly detecting cellular features that facilitate comparative analysis of the studied predictors. 相似文献
50.
Miguel de la Fuente Iaki Rodríguez-Agirretxe Elena Vecino Egoitz Astigarraga Arantxa Acera Gabriel Barreda-Gmez 《International journal of molecular sciences》2022,23(10)
Matrix metalloproteinases are a family of enzymes fundamental in inflammatory processes. Between them, MMP-9 is up-regulated during inflammation; thus, its quantification in non-invasive fluids is a promising approach for inflammation identification. To this goal, a biomarker quantification test was developed for ocular inflammation detection using anti-MMP-9 antibody microarrays (AbMAs). After validation with eight healthy control tear samples characterized by ELISA, 20 samples were tested from individuals diagnosed with ocular inflammation due to: cataracts, glaucoma, meibomian gland dysfunction, allergy, or dry eye. Concentration values of tear MMP-9 were obtained for each sample, and 12 patients surpassed the pathological threshold (30 ng/mL). A significant elevation of MMP-9 concentration in the tears of glaucoma patients compared with healthy controls was observed. In order to evaluate the diagnostic ability, an ROC curve analysis was performed using our data, determining the optimal threshold for the test at 33.6 ng/mL of tear MMP-9. In addition, a confusion matrix was applied, estimating sensitivity at 60%, specificity at 88%, and accuracy at 68%. In conclusion, we demonstrated that the AbMAs system allows the quantification of MMP-9 in pathologies that involve inflammation of the ocular surface. 相似文献