全文获取类型
收费全文 | 2132篇 |
免费 | 41篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 27篇 |
化学工业 | 318篇 |
金属工艺 | 23篇 |
机械仪表 | 42篇 |
建筑科学 | 112篇 |
矿业工程 | 28篇 |
能源动力 | 58篇 |
轻工业 | 240篇 |
水利工程 | 20篇 |
石油天然气 | 5篇 |
无线电 | 158篇 |
一般工业技术 | 250篇 |
冶金工业 | 493篇 |
原子能技术 | 17篇 |
自动化技术 | 383篇 |
出版年
2023年 | 10篇 |
2022年 | 27篇 |
2021年 | 35篇 |
2020年 | 16篇 |
2019年 | 27篇 |
2018年 | 30篇 |
2017年 | 31篇 |
2016年 | 29篇 |
2015年 | 32篇 |
2014年 | 45篇 |
2013年 | 126篇 |
2012年 | 74篇 |
2011年 | 119篇 |
2010年 | 85篇 |
2009年 | 111篇 |
2008年 | 97篇 |
2007年 | 98篇 |
2006年 | 82篇 |
2005年 | 91篇 |
2004年 | 64篇 |
2003年 | 56篇 |
2002年 | 54篇 |
2001年 | 40篇 |
2000年 | 39篇 |
1999年 | 45篇 |
1998年 | 84篇 |
1997年 | 70篇 |
1996年 | 52篇 |
1995年 | 43篇 |
1994年 | 43篇 |
1993年 | 38篇 |
1992年 | 28篇 |
1991年 | 22篇 |
1990年 | 20篇 |
1989年 | 19篇 |
1988年 | 18篇 |
1987年 | 15篇 |
1986年 | 23篇 |
1985年 | 24篇 |
1984年 | 13篇 |
1983年 | 15篇 |
1982年 | 11篇 |
1981年 | 9篇 |
1980年 | 12篇 |
1979年 | 10篇 |
1978年 | 15篇 |
1977年 | 13篇 |
1976年 | 27篇 |
1975年 | 7篇 |
1974年 | 10篇 |
排序方式: 共有2174条查询结果,搜索用时 15 毫秒
1.
Detector physics and simulation of resistive plate chambers 总被引:1,自引:0,他引:1
Werner Riegler Christian Lippmann Rob Veenhof 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2003,500(1-3):144-162
We present a simulation model suited to study efficiency, timing and pulse-height spectra of Resistive Plate Chambers. After discussing the details of primary ionisation, avalanche multiplication, signal induction and frontend electronics, we apply the model to timing RPCs with time resolution down to 50 ps and trigger RPCs with time resolution of about 1 ns. 相似文献
2.
Predicting Forest Age Classes from High Spatial Resolution Remotely Sensed Imagery Using Voronoi Polygon Aggregation 总被引:1,自引:0,他引:1
Efficient identification of forest age is useful for forest management and ecological applications. Here we propose a user-assisted method for determining forest age using high spatial resolution remotely sensed imagery. This method requires individual trees to be extracted from imagery and represented as points. We use a local maximum filter to generate points that are converted to Voronoi polygons. Properties of the Voronoi polygons are correlated with forest age and used to aggregate points (trees) into areas (stands) based on three forest age classes. Accuracy of the aggregation ranges from approximately 68% to 78% and identification of the mature class is more consistent and accurate than the younger classes. 相似文献
3.
The author relates his experiences in a small software development company. These experiences show that project management is challenging and if the project manager is an obstacle, the project is bound to fail. When it does, it can spell disaster for the manager and anyone who accompanies him or her on a software development journey. 相似文献
4.
We present a new algorithm,
called MCS-M,
for computing minimal triangulations of graphs.
Lex-BFS, a seminal algorithm for recognizing chordal graphs,
was the genesis for two other classical algorithms:
LEX M and MCS.
LEX M extends the fundamental concept used in Lex-BFS,
resulting in an algorithm that not only recognizes chordality,
but also computes a minimal triangulation of an arbitrary graph.
MCS simplifies the fundamental concept used in Lex-BFS,
resulting in a simpler algorithm for recognizing chordal graphs.
The new algorithm MCS-M combines
the extension of LEX M with the simplification of MCS,
achieving all the results of LEX M in the same time complexity. 相似文献
5.
Aard J. Groen Petra C. De WeerdNederhof Inge C. Kerssensvan Drongelen Rob A.J. Badoux Gerard P.H. Olthuis 《Creativity & Innovation Management》2002,11(1):2-16
In this paper we describe a framework for analysing the creation and justification of Research & Development. The 4S framework is developed for analysing the scope, scale, skills and social network aspects of Research & Development value. The framework is based on social system theory, a process contingency model, and recent Research & Development metrics. We present a first empirical assessment based on a workshop using the 4S framework for leveraging Research & Development. Results that assist in the assessment of value creation utilising R & D within networks are very relevant in high tech industries. The multi–dimensional process approach of this framework seems promising for understanding and managing R&D value creation, but needs further operationalisation. Case studies are described and a Dutch network on leveraging R&D has been initiated. 相似文献
6.
We have studied the inhibitory action of long- and short-chain fatty acids on hepatic glucose utilization in hepatocytes isolated from fasted rats. The rates of hepatic glucose phosphorylation and glycolysis were determined from the tritiated products of [2-3H] and [6-3H]glucose metabolism, respectively. The difference between these was taken as an estimate of the 'cycling' between glucose and glucose-6-phosphate. In the presence of 40 mM glucose this cycling was estimated at 0.68 mumol/min/g wet wt. Glucose phosphorylation was unaffected during palmitate and hexanoate oxidation to ketone bodies but glycolysis was inhibited. The rate of glucose cycling was increased during this phase to 1.25 mumol/min/g. Following the complete metabolism of the fatty acids, glycolysis was reinstated and cycling rates returned to control levels. Hepatic glucose cycling appears to be an important component of the glucose/fatty acid cycle. 相似文献
7.
The standard enzymatic assay for quantification of D-sorbitol in plasma was adapted to the automatic analyzer Cobas Mira S. In the assay, NAD (reagent) in the presence of sorbitoldehydrogenase (SDH; start reagent) converts D-sorbitol to fructose with formation of NADH, which was detected automatically as the difference between the first and last readings at 340 nm. The sample blank values for each specimen were subtracted to exclude both endogenous D-sorbitol and sugars, which also react as substrates for SDH. The method is simple, rapid (40 samples/h), precise down to endogenous concentrations (coefficient of variation < 5%; limit of determination: 0.38 mg/L) and linear up to 100 mg/L. Samples with higher D-sorbitol concentrations were estimated after dilution. The method was used to measure disposition curves of sorbitol in volunteers after a single intravenous dose of 0.8 g sorbitol. 相似文献
8.
A prospectively studied group of 55 uncemented Press Fit Condylar total knee arthroplasties was compared retrospectively with a matched group of 51 cemented Press Fit Condylar total knee arthroplasties at a mean of 10 years after operation. For the cemented group, the pain and function scores improved from 32 and 45 preoperatively to 95 and 77, respectively. For the uncemented group the scores improved from 33 and 50 preoperatively to 93 and 60, respectively. There were 10 revisions in the uncemented group for femoral or tibial aseptic loosening or osteolysis compared with two revisions in the cemented group. Exclusive of problems related to patellar metal backing, survival to revision for aseptic failure or radiographic loosening was 72% in the uncemented group and 94% in the cemented group at 10 years. A significantly higher revision rate was found in the uncemented compared with cemented total knee arthroplasty of the Press Fit Condylar design. 相似文献
9.
Document caching and connection caching are extensively studied problems. In document caching, one has to maintain caches
containing documents accessible in a network. In connection caching, one has to maintain a set of open network connections
that handle data transfer. Previous work investigated these two problems separately while in practice the problems occur together:
In order to load a document, one has to establish a connection between network nodes if the required connection is not already
open. In this paper we present the first study that integrates document and connection caching. We first consider a very basic
model in which all documents have the same size and the cost of loading a document or establishing a connection is equal to
1. We present deterministic and randomized online algorithms that achieve nearly optimal competitive ratios unless the size
of the connection cache is extremely small. We then consider general settings where documents have varying sizes. We investigate
a FAULT model in which the loading cost of a document is 1 as well as a BIT model in which the loading cost is equal to the
size of the document. 相似文献
10.