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   18549篇
  免费   2662篇
  国内免费   969篇
电工技术   6136篇
技术理论   2篇
综合类   1128篇
化学工业   1047篇
金属工艺   245篇
机械仪表   751篇
建筑科学   578篇
矿业工程   217篇
能源动力   2953篇
轻工业   208篇
水利工程   542篇
石油天然气   813篇
武器工业   79篇
无线电   1840篇
一般工业技术   1176篇
冶金工业   383篇
原子能技术   120篇
自动化技术   3962篇
  2024年   133篇
  2023年   443篇
  2022年   747篇
  2021年   897篇
  2020年   897篇
  2019年   769篇
  2018年   635篇
  2017年   853篇
  2016年   868篇
  2015年   890篇
  2014年   1379篇
  2013年   1192篇
  2012年   1453篇
  2011年   1639篇
  2010年   1125篇
  2009年   1191篇
  2008年   1025篇
  2007年   1025篇
  2006年   871篇
  2005年   719篇
  2004年   569篇
  2003年   443篇
  2002年   396篇
  2001年   353篇
  2000年   310篇
  1999年   228篇
  1998年   179篇
  1997年   161篇
  1996年   139篇
  1995年   121篇
  1994年   99篇
  1993年   85篇
  1992年   68篇
  1991年   58篇
  1990年   43篇
  1989年   28篇
  1988年   16篇
  1987年   15篇
  1986年   13篇
  1985年   22篇
  1984年   19篇
  1983年   11篇
  1982年   9篇
  1981年   6篇
  1980年   11篇
  1979年   5篇
  1978年   5篇
  1977年   6篇
  1976年   3篇
  1974年   3篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
本文给出从指称语义自动生成解释器后端的一种技术.解释器被表示成PASCAL_like形式.  相似文献   
62.
This paper presents a partial scan algorithm, calledPARES (PartialscanAlgorithm based onREduced Scan shift), for designing partial scan circuits. PARES is based on the reduced scan shift that has been previously proposed for generating short test sequences for full scan circuits. In the reduced scan shift method, one determines proch FFs must be controlled and observed for each test vector. According to the results of similar analysis, PARES selects these FFs that must be controlled or observed for a large number of test vectors, as scanned FFs. Short test sequences are generated by reducing scan shift operations using a static test compaction method. To minimize the loss of fault coverage, the order of test vectors is so determined that the unscanned FFs are in the state required by the next test vector. If there are any faults undetected yet by a test sequence derived from the test vectors, then PARES uses a sequential circuit test generator to detect the faults. Experimental results for ISCAS'89 benchmark circuits are given to demonstrate the effectiveness of PARES.  相似文献   
63.
Due to technology scaling and increasing clock frequency, problems due to noise effects lead to an increase in design/debugging efforts and a decrease in circuit performance. This paper addresses the problem of efficiently and accurately generating two-vector tests for crosstalk induced effects, such as pulses, signal speedup and slowdown, in digital combinational circuits. These noise effects can propagate through a circuit and create a logic error in a latch or at a primary output. We have developed a mixed-signal test generator, called XGEN, that incorporates classical static values as well as dynamic signals such as transitions and pulses, and timing information such as signal arrival times, rise/fall times, and gate delay. In this paper we first discuss the general framework of the test generation algorithm followed by computational results. Comparison of results with SPICE simulations confirms the accuracy of this approach.  相似文献   
64.
本文结合为某机械厂开发的实用计算机辅助工艺设计系统(JJCAPP),论述了一种兼有派生式和创成式特点的综合式工艺自动设计方法.  相似文献   
65.
刘鹏 《山西电子技术》2004,(4):22-24,39
在光纤高速传输技术、光交换与智能光网等与宽带接入、多媒体、3G等网络应用技术的推动下,建设基于IPv6协议的IP基础电信网成为可能。现在IP网正在朝着有序的、可管理的、有QoS保障的、可以支持各类业务的综合业务基础网演进。电信网也正在从网络接入层上、从长途网络层面上、从本地网络层面上、从固定网向含3G在内的移动网络等方面向支持IP技术及其综合业务的方面全面推进。  相似文献   
66.
When a linear voltage ramp is applied to the gate of a MOS capacitor, a capacitancetime (C-t) transient is observed. The MOS capacitor is biased into strong inversion before applying the voltage ramp in order to eliminate surface generation. FromC-t transient curve obtained experimentally the minority carrier generation lifetime in semiconductor can be determined. The experimental results show that for the same sample the lifetimes extracted fromC-t curves under varying voltage sweep rates are close each other, and they are consistent with the lifetimes extracted by saturation capacitance method.  相似文献   
67.
In this paper we derive kinetic parameters for the generation of gaseous hydrocarbons (C1‐5) and methane (C1) from closed‐system laboratory pyrolysis of selected samples of marine kerogen and oil from the SW Tarim Basin. The activation energy distributions for the generation of both C1‐5 (Ea = 59‐72kcal, A = 1.0×1014 s?1) and C1 (Ea = 61‐78kcal, A = 6.06×1014 s?1) hydrocarbons from the marine oil are narrower than those for the generation of these hydrocarbons from marine kerogen (Ea = 50‐74kcal, A = 1.0×1014 s?1 for C1‐5; and Ea = 48‐72kcal, A=3.9×1013 s?1 for C1, respectively). Using these kinetic parameters, both the yields and timings of C1‐5 and C1 hydrocarbons generated from Cambrian source rocks and from in‐reservoir cracking of oil in Ordovician strata were predicted for selected wells along a north‐south profile in the SW of the basin. Thermodynamic conditions for the cracking of oil and kerogen were modelled within the context of the geological framework. It is suggested that marine kerogen began to crack at temperatures of around 120°C (or 0.8 %Ro) and entered the gas window at 138°C (or 1.05 %Ro); whereas the marine oil began to crack at about 140 °C (or 1.1 %Ro) and entered the gas window at 158 °C (or 1.6%Ro). The main geological controls identified for gas accumulations in the Bachu Arch (Southwest Depression, SW Tarim Basin) include the remaining gas potential following Caledonian uplift; oil trapping and preservation in basal Ordovician strata; the extent of breaching of Ordovician reservoirs; and whether reservoir burial depths are sufficiently deep for oil cracking to have occurred. In the Maigaiti Slope and Southwest Depression, the timing of gas generation was later than that in the Bachu Arch, with much higher yields and generation rates, and hence better prospects for gas exploration. It appears from the gas generation kinetics that the primary source for the gases in the Hetianhe gasfield was the Southwest Depression.  相似文献   
68.
从IP QoS技术的研究现状出发,结合IETF的研究成果与电信网NGN的技术发展方向,阐述基于策略的端到端接纳控制框架的技术原理,在各大标准组织的技术框架内,给出一个具体的、切实可行的实现方法。  相似文献   
69.
The development of renewable technologies in the last decade has been exceptional. In photovoltaic (PV) for example, efforts were not only limited to merely improving their efficiency but also to the reduction of the cost of cells and modules via volume production for commercial markets. There are many national schemes promoting the use of PV technology and regional targets for a share of renewable energy production. This paper attempts to relay to the reader a journey, based on experience, approaches for enhancing the prospect of utilising solar energy within the society we live in. The issue of expansion or enhancing the utilisation of solar energy can be undertaken by individuals, groups, institutions and governments. The aim of this paper is to provide some examples, which could serve as a framework in which action could be taken to promote solar technology.  相似文献   
70.
1 . INTRODUCTIONWhenhigh speedairfloworcurrentpassesovergapsorcavitiesinaflatplate ,self excitedoscillationsmayoccur ,leadingtodramaticpressureandvelocityfluctuationandintensivenoise .Thesephenomenamayappearinmanyengineeringapplications .Forexample ,weaponb…  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