首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1800篇
  免费   69篇
  国内免费   2篇
电工技术   13篇
综合类   1篇
化学工业   315篇
金属工艺   42篇
机械仪表   23篇
建筑科学   62篇
矿业工程   9篇
能源动力   46篇
轻工业   137篇
水利工程   15篇
石油天然气   7篇
无线电   159篇
一般工业技术   367篇
冶金工业   433篇
原子能技术   15篇
自动化技术   227篇
  2023年   13篇
  2022年   27篇
  2021年   36篇
  2020年   36篇
  2019年   41篇
  2018年   49篇
  2017年   44篇
  2016年   40篇
  2015年   30篇
  2014年   49篇
  2013年   88篇
  2012年   81篇
  2011年   117篇
  2010年   86篇
  2009年   58篇
  2008年   101篇
  2007年   75篇
  2006年   69篇
  2005年   72篇
  2004年   56篇
  2003年   65篇
  2002年   45篇
  2001年   26篇
  2000年   33篇
  1999年   33篇
  1998年   26篇
  1997年   35篇
  1996年   36篇
  1995年   26篇
  1994年   30篇
  1993年   20篇
  1992年   19篇
  1991年   11篇
  1990年   22篇
  1989年   22篇
  1988年   18篇
  1987年   14篇
  1986年   9篇
  1985年   17篇
  1984年   13篇
  1983年   25篇
  1982年   12篇
  1981年   13篇
  1980年   9篇
  1979年   26篇
  1978年   15篇
  1977年   17篇
  1976年   9篇
  1973年   8篇
  1972年   8篇
排序方式: 共有1871条查询结果,搜索用时 12 毫秒
21.
Creating high-quality quad meshes from triangulated surfaces is a highly nontrivial task that necessitates consideration of various application specific metrics of quality. In our work, we follow the premise that automatic reconstruction techniques may not generate outputs meeting all the subjective quality expectations of the user. Instead, we put the user at the center of the process by providing a flexible, interactive approach to quadrangulation design. By combining scalar field topology and combinatorial connectivity techniques, we present a new framework, following a coarse to fine design philosophy, which allows for explicit control of the subjective quality criteria on the output quad mesh, at interactive rates. Our quadrangulation framework uses the new notion of Reeb atlas editing, to define with a small amount of interactions a coarse quadrangulation of the model, capturing the main features of the shape, with user prescribed extraordinary vertices and alignment. Fine grain tuning is easily achieved with the notion of connectivity texturing, which allows for additional extraordinary vertices specification and explicit feature alignment, to capture the high-frequency geometries. Experiments demonstrate the interactivity and flexibility of our approach, as well as its ability to generate quad meshes of arbitrary resolution with high-quality statistics, while meeting the user’s own subjective requirements.  相似文献   
22.
The human plasma high density lipoproteins (HDL) are a heterogeneous ensemble of five proteins associated with both neutral and polar lipids. The sequences of all five proteins are known. ApoA-I and apoA-II are the major protein components; apoC-I, apoC-II and apoC-III are the minor protein components. All these apoproteins spontaneously recombine with phospholipids to give stable lipid-protein complexes and freely exchange between the two major HDL subclasses, HDL2 and HDL3. In addition, ApoC-I, apoC-II, and apoC-III exchange between HDL and very low density lipoproteins. Furthermore, certain HDL apoproteins are activators for plasma enzymes that are important in lipid metabolism. ApoA-I and apoC-I activate lecithin/cholesterol acyltransferase; apoC-II is an activator of lipoprotein lipase. The regions of apoC-I and apoC-II that are involved in the activation of these enzymes have been localized with synthetic peptides. Studies of synthetic and native fragments of apoA-II, apoC-I, apoC-II, and apoC-III as well as model lipid-binding peptides have identified specific regions with structural features common to lipid-binding proteins. These special properties, which include helical potential, sequences with a critical amphipathic length, and high hydrophobicity of the nonpolar side of the amphipathic helix, are the determinants of HDL structure and metabolism.  相似文献   
23.
Similarity search in high-dimensional spaces is a pivotal operation for several database applications, including online content-based multimedia services. With the increasing popularity of multimedia applications, these services are facing new challenges regarding (1) the very large and growing volumes of data to be indexed/searched and (2) the necessity of reducing the response times as observed by end-users. In addition, the nature of the interactions between users and online services creates fluctuating query request rates throughout execution, which requires a similarity search engine to adapt to better use the computation platform and minimize response times. In this work, we address these challenges with Hypercurves, a flexible framework for answering approximate k-nearest neighbor (kNN) queries for very large multimedia databases. Hypercurves executes in hybrid CPU–GPU environments and is able to attain massive query-processing rates through the cooperative use of these devices. Hypercurves also changes its CPU–GPU task partitioning dynamically according to the observed load, aiming for optimal response times. In our empirical evaluation, dynamic task partitioning reduced query response times by approximately 50 % compared to the best static task partition. Due to a probabilistic proof of equivalence to the sequential kNN algorithm, the CPU–GPU execution of Hypercurves in distributed (multi-node) environments can be aggressively optimized, attaining superlinear scalability while still guaranteeing, with high probability, results at least as good as those from the sequential algorithm.  相似文献   
24.
Charge transfer complexes possessing a … DADA … structure with both the donor, D, and acceptor, A, being S = 1/2 radicals may exhibit cooperative magnetic phenomena. The complex [Fe(C5Me5)2]+·[TCNQ]· exhibits metamagnetic behavior. The similarly structured [TCNE]· and [C4(CN)6]· complexes are ferromagnets, whereas the [DDQ]· salt is a paramagnet. The high temperature magnetic susceptibility obeys the Curie-Weiss expression with θ = + 30, + 30, and + 3 for the [TCNE]·, [C4(CN)6]·, and [TCNQ]· salts, respectively. The ferromagnetic [TCNE]· salt exhibits zero field Zeeman split 57Fe Mossbauer spectra with an internal field of 425.6 kOe at 4.23 K. After reviewing the current papers discussing ferromagnetism in molecular (organic) compounds, a qualitative model consistent with the necessary bulk spin alignment required for a ferromagnet is presented.  相似文献   
25.
Cognition, Technology & Work - Simulator training is becoming increasingly important for training of time-critical and dynamic situations. Hence, how simulator training in such domains is...  相似文献   
26.
Abstract

The course SDR: Sistemas de Representación(Systems of Representation), is the last stage of a line of work which has the objective of integrating information technologies in the education of architecture in a meaningful way. A distinctive mark of this pedagogic approach has been to look upon computer technology as an opportunity to rethink the methods, contents and goals of architecturaleducation,in thelight of contemporary culture.

The course is structured in six themes, each one standing for a ‘system of representation’: ‘text’, ‘figure’, ‘object’, ‘image’, ‘space’ and ‘light’. Within every system, a variety of issues dealing with the concept of ‘representation’ are addressed in an interdisciplinary manner. It is a compulsory course lasting three semesters, in the second and third year of a five-year architectural program. It has been offered since the academic year 1999/2000.  相似文献   
27.
Provides an overview of the 1995 Consumer Reports survey of the effectiveness of psychotherapy. Specific issues addressed include the study's goals; the findings for mental health professionals, family doctors, and self-help groups; and methodological strengths and weaknesses related to external validity, sampling, controls, self-reports, and time frame. The data show that, free of the artificial constraints of controlled studies in the real world, a population of consumers can often benefit from psychological intervention services. Real relief can be found at the hands of professional mental health providers. M. Kotkin et al reaffirm their independence from M. E. P. Seligman (see record 1996-13324-001) regarding the interpretation of the data. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
28.
由于Joel Spolsky的双重身份(昔日耶鲁大学计算机系学长,今日Fog Creek软件公司的OEO),所以听听他的建议,对于当今无数困扰于就业压力的中国高校计算机专业学子来说,是大有裨益的。你们会发现,大多数建议,都在强调“软实力”的价值。本文转载自《软件随想录》(作者:Joel Spolsky,译者:阮一峰,2009年12月出版),感谢北京图灵文化发展有限公司的支持。  相似文献   
29.
Scheduling, in many application domains, involves optimization of multiple performance metrics. For example, application workflows with real-time constraints have strict throughput requirements and also desire a low latency or response time. In this paper, we present a novel algorithm for the scheduling of workflows that act on a stream of input data. Our algorithm focuses on the two performance metrics, latency and throughput, and minimizes the latency of workflows while satisfying strict throughput requirements. We also describe steps to use the above approach to solve the problem of meeting latency requirements while maximizing throughput. We leverage pipelined, task and data parallelism in a coordinated manner to meet these objectives and investigate the benefit of task duplication in alleviating communication overheads in the pipelined schedule for different workflow characteristics. The proposed algorithm is designed for a realistic bounded multi-port communication model, where each processor can simultaneously communicate with at most k distinct processors. Experimental evaluation using synthetic benchmarks as well as those derived from real applications shows that our algorithm consistently produces lower latency schedules that meet throughput requirements, even when previously proposed schemes fail.  相似文献   
30.
This paper describes a novel template-based meshing approach for generating good quality quadrilateral meshes from 2D digital images. This approach builds upon an existing image-based mesh generation technique called Imeshp, which enables us to create a segmented triangle mesh from an image without the need for an image segmentation step. Our approach generates a quadrilateral mesh using an indirect scheme, which converts the segmented triangle mesh created by the initial steps of the Imesh technique into a quadrilateral one. The triangle-to-quadrilateral conversion makes use of template meshes of triangles. To ensure good element quality, the conversion step is followed by a smoothing step, which is based on a new optimization-based procedure. We show several examples of meshes generated by our approach, and present a thorough experimental evaluation of the quality of the meshes given as examples.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号