首页 | 官方网站   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   701165篇
  免费   9648篇
  国内免费   2244篇
工业技术   713057篇
  2021年   6044篇
  2020年   4440篇
  2019年   5624篇
  2018年   9454篇
  2017年   9288篇
  2016年   9855篇
  2015年   6975篇
  2014年   11573篇
  2013年   32673篇
  2012年   18833篇
  2011年   26409篇
  2010年   20681篇
  2009年   23195篇
  2008年   23981篇
  2007年   23604篇
  2006年   21008篇
  2005年   19171篇
  2004年   18393篇
  2003年   18170篇
  2002年   17175篇
  2001年   17415篇
  2000年   16122篇
  1999年   17226篇
  1998年   43976篇
  1997年   30698篇
  1996年   23362篇
  1995年   17595篇
  1994年   15315篇
  1993年   15004篇
  1992年   10754篇
  1991年   10102篇
  1990年   9814篇
  1989年   9460篇
  1988年   8904篇
  1987年   7676篇
  1986年   7503篇
  1985年   8648篇
  1984年   8020篇
  1983年   7148篇
  1982年   6709篇
  1981年   6856篇
  1980年   6413篇
  1979年   6197篇
  1978年   5862篇
  1977年   7058篇
  1976年   9168篇
  1975年   5059篇
  1974年   4742篇
  1973年   4940篇
  1972年   3927篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
991.
Grace  D. Burr  A.G. Tozer  T.C. 《Electronics letters》1996,32(21):1956-1957
The performance of two distributed channel assignment algorithms which use coexistence etiquettes for point to point links are considered by the authors. It has been found that selecting channels prior to transmission at the transmitter as opposed to the receiver, supports greater offered traffic with the additional advantage of a less complex protocol  相似文献   
992.
One or more layers of textiles can provide a thermal resistance between the human body and its environment, and so help maintain the body in a thermally comfortable state. The effect of wind on and its penetration through such thermal cladding is examined experimentally.  相似文献   
993.
The newly developed ingot growing techniques, as the three-grain and the columnar multigrain ingot processes, are now offering the possibility of slicing thinner wafers (≤ 100 μm). In this paper we present the results obtained on p type large area (≥ 100 cm2) and 100 μm thick wafers by using both conventional and reverse cell manufacturing technologies.The conventional cells are provided with aluminium or boron BSF plus screen-printed silver mirror or a silver-aluminium net; the reverse cells have a FSF and the deep back junction completely covered by a screen-printed or CVD silver layer.The constructing parameters have been chosen on the base of one and two dimensions modeling and both raw material and devices have been completely characterized.This work shows that very thin wafers do not introduce serious problems for the conventional manufacturing of solar cells. The efficiencies of the normal and of the reverse cells are found to be comparable and are of the same order than those of thicker cells, however at a significant lower cost. The main obtained result has to be related to the demonstration of a cell manufacturing feasibility starting from very thin wafers.  相似文献   
994.
The simulation of a complete induction motor drive is presented. The entire network is modelled using the transmission-line modelling (TLM) technique. The network is split into three sections which are solved independently and are joined together by link transmission-line models. Advantages of this approach are the explicit nature of the algorithm which remains unaltered irrespective of the network topology, unconditional stability, and straightforward modelling of switching elements. Results are presented for a complete drive which illustrate the capabilities and flexibility of the simulation technique  相似文献   
995.
996.
Markets and Hierarchies and (Mathematical) Economic Theory   总被引:4,自引:0,他引:4  
Over the past decade transaction-cost economics has been partiallytranslated in the more mathematical language of game theory,and understanding of the costs of transactions has been deepened,refined and extended. But the translation is incomplete: a greatdeal of human behaviour is missed, and doing game theory withmore life-like models of individuals will bring theory closerto phenomena. Transaction-cost economics, particulary the economicsof relational contracts, provides a major arena for these developments,since the important issues of bounded rationality and individualbehavior are central to the topic.  相似文献   
997.
998.
999.
We obtain expressions for biased estimates for parameters of binomial distributions with allowance fora priori information; our starting poins is the Rao-Kramer inequality. Translated from Izmeritel'naya Tekhnika, No. 10, pp. 14–16, October, 1996.  相似文献   
1000.
The author studies dynamic scheduling of computational tasks with communication costs using nonuniform memory access architecture. The computing model assumes that data transfer can be partitioned into parallel and sequential parts with respect to the task execution. A scheduling heuristic, called least-communication (LC), together with a two-level scheduler is proposed in an attempt to minimize the finish time. The LC selects the task that removes the largest amount of remaining data transfer, if no such tasks are available the task that has been ready to run at the earliest is selected first. The time complexity of LC is O(n2). Testing the finish time of LC and first-come first-served scheduling (FCFS) shows that LC is useful for tasks having moderate granularity and whose computation and communication requirements vary widely for different data sets  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-23

京公网安备 11010802026262号