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   7620篇
  免费   407篇
  国内免费   14篇
电工技术   85篇
综合类   2篇
化学工业   1871篇
金属工艺   174篇
机械仪表   145篇
建筑科学   281篇
矿业工程   13篇
能源动力   245篇
轻工业   707篇
水利工程   75篇
石油天然气   28篇
武器工业   6篇
无线电   558篇
一般工业技术   1577篇
冶金工业   846篇
原子能技术   43篇
自动化技术   1385篇
  2023年   56篇
  2022年   120篇
  2021年   168篇
  2020年   160篇
  2019年   134篇
  2018年   179篇
  2017年   197篇
  2016年   252篇
  2015年   167篇
  2014年   270篇
  2013年   609篇
  2012年   450篇
  2011年   549篇
  2010年   370篇
  2009年   370篇
  2008年   501篇
  2007年   425篇
  2006年   370篇
  2005年   304篇
  2004年   281篇
  2003年   242篇
  2002年   201篇
  2001年   124篇
  2000年   101篇
  1999年   114篇
  1998年   125篇
  1997年   103篇
  1996年   101篇
  1995年   92篇
  1994年   108篇
  1993年   78篇
  1992年   63篇
  1991年   52篇
  1990年   46篇
  1989年   64篇
  1988年   47篇
  1987年   24篇
  1986年   31篇
  1985年   40篇
  1984年   41篇
  1983年   26篇
  1982年   26篇
  1981年   41篇
  1980年   24篇
  1979年   22篇
  1978年   24篇
  1977年   14篇
  1975年   11篇
  1974年   21篇
  1973年   14篇
排序方式: 共有8041条查询结果,搜索用时 15 毫秒
21.
From Non-Functional Requirements to Design through Patterns   总被引:8,自引:2,他引:6  
  相似文献   
22.
You can survive after death in various kinds of artifacts. You can survive in diaries, photographs, sound recordings, and movies. But these artifacts record only superficial features of yourself. We are already close to the construction of programs that partially and approximately replicate entire human lives (by storing their memories and duplicating their personalities). A digital ghost is an artificially intelligent program that knows all about your life. It is an animated auto-biography. It replicates your patterns of belief and desire. You can survive after death in a digital ghost. We discuss a series of digital ghosts over the next 50 years. As time goes by and technology advances, they are progressively more perfect replicas of the lives of their original authors.
Eric SteinhartEmail: Email: URL: http://www.wpunj.edu/cohss/philosophy/steinhart
  相似文献   
23.
Identification of statistical patterns from observed time series of spatially distributed sensor data is critical for performance monitoring and decision making in human-engineered complex systems, such as electric power generation, petrochemical, and networked transportation. This paper presents an information-theoretic approach to identification of statistical patterns in such systems, where the main objective is to enhance structural integrity and operation reliability. The core concept of pattern identification is built upon the principles of Symbolic Dynamics, Automata Theory, and Information Theory. To this end, a symbolic time series analysis method has been formulated and experimentally validated on a special-purpose test apparatus that is designed for data acquisition and real-time analysis of fatigue damage in polycrystalline alloys.  相似文献   
24.
Odourous emissions from sewer networks and wastewater treatment plants (WWTPs) can significantly impact a local population. Sampling techniques such as wind tunnels and flux hood chambers are traditionally used to collect area source samples for subsequent quantification of odour emission rates using dilution olfactometry, however these methods are unsuitable for assessing liquid samples from point sources due to the large liquid volumes required. To overcome this limitation, a gas phase sample preparation method was developed for assessing the total Odour Emission Ability (OEA) from a liquid sample. The method was validated using two volatile organic sulphur compounds (VOSCs), dimethyl-trisulphide (DMTS) and bismethylthiomethane (BMTM) that are frequently detected from sewers and WWTPs and are relatively stable compared with common VOSCs like mercaptan or methyl mercaptan. The recovery rates of DMTS and BMTM were quantified by injecting a known volume of a standard liquid sample into Tedlar bags using a static injection and a dynamic injection methodology. It was confirmed that both dynamic and static injection methods at ambient condition achieved high recovery rates with no need to consider increasing evaporation by elevating the temperature. This method can also be used to assess odour removal effectiveness of liquids by comparing the OEA before and after the treatment tests. Two application examples were presented.  相似文献   
25.
A software architecture is presented that allows client application programs to interact with a DBMS server in a flexible and powerful way, using either direct, volatile messages, or messages sent via recoverable queues. Normal requests from clients to the server and replies from the server to clients can be transmitted using direct or recoverable messages. In addition, an application event notification mechanism is provided, whereby client applications running anywhere on the network can register for events, and when those events are raised, the clients are notified. A novel parameter passing mechanism allows a set of tuples to be included in an event notification. The event mechanism is particularly useful in an active DBMS, where events can be raised by triggers to signal running application programs. Received July 21, 1995 / Accepted May 30, 1996  相似文献   
26.
27.
Transcatheter aortic valve replacement (TAVR), as an alternative to open heart surgery, has revolutionized the treatment of severe aortic valve stenosis (AVS), the most common valvular disorder in the elderly. AVS is now considered a form of atherosclerosis and, like the latter, partly of inflammatory origin. Patients with high-grade AVS have a highly disturbed blood flow associated with high levels of shear stress. The immediate reopening of the valve during TAVR leads to a sudden restoration of a normal blood flow hemodynamic. Despite its good prognosis for patients, TAVR remains associated with bleeding or thrombotic postprocedural complications, involving mechanisms that are still poorly understood. Many studies report the close link between blood coagulation and inflammation, termed thromboinflammation, including monocytes as a major actor. The TAVR procedure represents a unique opportunity to study the influence of shear stress on human monocytes, key mediators of inflammation and hemostasis processes. The purpose of this study was to conduct a review of the literature to provide a comprehensive overview of the impact of TAVR on monocyte phenotype and subset repartition and the association of these parameters with the clinical outcomes of patients with severe AVS who underwent TAVR.  相似文献   
28.
Adipocyte iron overload is a maladaptation associated with obesity and insulin resistance. The objective of the current study was to determine whether and how adipose tissue macrophages (ATMs) regulate adipocyte iron concentrations and whether this is impacted by obesity. Using bone marrow-derived macrophages (BMDMs) polarized to M0, M1, M2, or metabolically activated (MMe) phenotypes, we showed that MMe BMDMs and ATMs from obese mice have reduced expression of several iron-related proteins. Furthermore, the bioenergetic response to iron in obese ATMs was hampered. ATMs from iron-injected lean mice increased their glycolytic and respiratory capacities, thus maintaining metabolic flexibility, while ATMs from obese mice did not. Using an isotope-based system, we found that iron exchange between BMDMs and adipocytes was regulated by macrophage phenotype. At the end of the co-culture, MMe macrophages transferred and received more iron from adipocytes than M0, M1, and M2 macrophages. This culminated in a decrease in total iron in MMe macrophages and an increase in total iron in adipocytes compared with M2 macrophages. Taken together, in the MMe condition, the redistribution of iron is biased toward macrophage iron deficiency and simultaneous adipocyte iron overload. These data suggest that obesity changes the communication of iron between adipocytes and macrophages and that rectifying this iron communication channel may be a novel therapeutic target to alleviate insulin resistance.  相似文献   
29.
The economics and performance of packet-switched satellite systems operating in a broadcast mode are studied and compared to landline-based systems similar to the ARPANET. The fixed-packet length inefficiencies and the satellite channel utilization of the satellite systems are presented as functions of the message length distribution, the number of earth stations, the average message delay, and the average number of messages generated at each earth station. Some of the economic factors in the design of packetswitched satellite networks are discussed, including hardware costs as a function of technology and system performance. Satellite network configurations with or without backhaul facilities are compared and it is concluded that configurations using backhaul facilities consisting of two 30 mile private leased lines (each 50 kbits/s) are more expensive. Parameters and estimated costs of satellite system configurations are presented and an engineering estimate of the cost function for satellite packet-switched networks is derived and presented in the form of long range average cost curves. Economies of scale with respect to network traffic and diseconomies of scale with respect to the number of network earth stations are found to be present.  相似文献   
30.
Wheat allergies are potentially life-threatening because of the high risk of anaphylaxis. Wheats belong to four genotypes represented in thousands of lines and varieties. Monitoring changes to wheat allergens is critical to prevent inadvertent ntroduction of hyper-allergenic varieties via breeding. However, validated methods for this purpose are unavailable at present. As a proof-of-concept study, we tested the hypothesis that salt-soluble wheat allergens in our mouse model will be identical to those reported for humans. Groups of Balb/cJ mice were rendered allergic to durum wheat salt-soluble protein extract (SSPE). Using blood from allergic mice, a mini hyper-IgE plasma bank was created and used in optimizing an IgE Western blotting (IEWB) to identify IgE binding allergens. The LC-MS/MS was used to sequence the allergenic bands. An ancient Aegilops tauschii wheat was grown in our greenhouse and extracted SSPE. Using the optimized IEWB method followed by sequencing, the cross-reacting allergens in A. tauschii wheat were identified. Database analysis showed all but 2 of the durum wheat allergens and all A. tauschii wheat allergens identified in this model had been reported as human allergens. Thus, this model may be used to identify and monitor potential changes to salt-soluble wheat allergens caused by breeding.  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