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   15419篇
  免费   1892篇
  国内免费   1399篇
电工技术   1001篇
综合类   2194篇
化学工业   285篇
金属工艺   289篇
机械仪表   936篇
建筑科学   1442篇
矿业工程   434篇
能源动力   288篇
轻工业   340篇
水利工程   492篇
石油天然气   247篇
武器工业   225篇
无线电   1543篇
一般工业技术   1047篇
冶金工业   935篇
原子能技术   70篇
自动化技术   6942篇
  2024年   53篇
  2023年   186篇
  2022年   313篇
  2021年   393篇
  2020年   489篇
  2019年   467篇
  2018年   445篇
  2017年   513篇
  2016年   558篇
  2015年   584篇
  2014年   869篇
  2013年   1068篇
  2012年   1022篇
  2011年   1154篇
  2010年   949篇
  2009年   950篇
  2008年   1024篇
  2007年   1225篇
  2006年   978篇
  2005年   906篇
  2004年   763篇
  2003年   674篇
  2002年   598篇
  2001年   470篇
  2000年   357篇
  1999年   306篇
  1998年   226篇
  1997年   206篇
  1996年   154篇
  1995年   141篇
  1994年   156篇
  1993年   91篇
  1992年   66篇
  1991年   63篇
  1990年   55篇
  1989年   33篇
  1988年   26篇
  1987年   18篇
  1986年   11篇
  1985年   12篇
  1984年   13篇
  1983年   17篇
  1982年   15篇
  1981年   7篇
  1980年   13篇
  1979年   13篇
  1978年   9篇
  1966年   7篇
  1958年   4篇
  1955年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
汽车侧倾稳定性的动态仿真(一) --数学模型的建立   总被引:1,自引:0,他引:1  
本文通过对独立悬架和非独立悬架侧倾运动特性的分析并结合采用已有的轮胎力学模型,建立了反映独立悬架和非独立悬架侧倾运动特性的数学模型。在此基础上,根据汽车侧倾时悬挂质量对前后悬架的力和力矩作用来组合前后悬架,我们得到了双轴汽车在稳态转向时侧倾运动的数学模型。通过组合不同的前后悬架,这个数学模型可以反映各种悬架配置的双轴汽车。它主要是针对汽车进行稳态转向时的侧倾情况,考虑了汽车的结构参数、惯性参数以及悬架、轮胎的柔性形变对汽车侧倾运动特性和抗侧翻能力的影响。它可以用来计算一定横向加速度下汽车的侧倾反应和轮胎的载荷变化,也可以用来计算一辆确定的汽车在保持侧倾稳定性的前提下所能达到的最大横向加速度,还可以用来分析各项参数对汽车侧倾稳定性的影响。  相似文献   
72.
The authors propose a behavioral decision theory relevant to the maintenance of desirable identities. The theory, termed deviance regulation theory (DRT), predicts that actions translate into meaningful identities to the extent that they cause the individual to deviate from reference group norms. This straightforward proposition is used to predict the patterning of behavior across a wide array of social contexts. The authors present evidence that predictions generalize across Eastern and Western cultures and to both personal and collective identities. Finally, they show how DRT alters current theoretical assumptions about social motives and social and cultural influence, and they illustrate how it can help explain the structure of both informal and formal social forces. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
73.
针对轧机产量提高后冷床冷却能力不足的问题 ,研制开发了棒材轧后穿水冷却技术。通过对小规格 2 0MnSiV热轧带肋钢筋进行轧后穿水冷却 ,钢材上冷床温度降低了 90~ 110℃ ,提高了产品质量 ,改善了各项力学性能 ,抗拉强度平均提高了 3 5~ 40MPa ,钢材性能合格率由 97.5 %提高到了 99.6% ,解决了冷床冷却能力不足、制约生产的瓶颈问题。  相似文献   
74.
决策支持系统是水库优化调度实用化的发展方向,对于提高水电站生产效益和水库调度管理水平具有重要意义。结合国电公司重点科技项目“天生桥梯级水电站联合调度决策支持系统”的开发,阐述了开发水电调度决策支持系统实现水库调度实用化的经验:正确反映用户需求、增强用户对系统的控制、用模拟仿真弥补优化调度的不足、用数据库技术扩展水库优化调度实用化功能。  相似文献   
75.
论述了银山型钢有限公司炼钢厂2#板坯连铸机自投产以来其振动台存在的问题,根据实际情况分析论证并进行改造实施,实施后效果明显。  相似文献   
76.
Pareto multi-criteria decision making   总被引:1,自引:0,他引:1  
The paper concerns design governed by multiple objective criteria, which are conflicting in the sense of competing for common resources to achieve variously different performance objectives (financial, functional, environmental, esthetical, etc.). A multi-criteria decision making (MCDM) strategy is proposed that employs a tradeoff-analysis technique to identify compromise designs for which the competing criteria are mutually satisfied in a Pareto-optimal sense. The MCDM strategy is initially developed for the case of design governed by n = 2 objective criteria. It is then extended to design governed by n > 2 objective criteria, by introducing the concept of primary and aggregate criteria. It is proved that, from among the theoretically infinite number of feasible designs forming the Pareto front for a design problem governed by n independent objective criteria, there exists a unique Pareto-compromise design that represents a mutually agreeable tradeoff between all n criteria. This remarkable result is illustrated for a flexural plate design governed by n = 2 criteria, a bridge maintenance-intervention protocol design governed by n = 3 criteria, and a media centre envelop design governed by n = 11 criteria.  相似文献   
77.
基于Solidworks的零件设计系列化   总被引:1,自引:0,他引:1  
通过实例介绍了利用Solidworks平台建立机械零件设计系列化的方法。它方便了缺少编程技术的设计人员,有助于提高设计效率,进而缩短产品研发周期,为企业赢得市场。  相似文献   
78.
Theorists have predicted that repetition blindness (RB) should be absent for nonwords because they do not activate preexisting mental types. The authors hypothesized that RB would be observed for nonwords because RB can occur at a sublexical level. Four experiments showed that RB is observed for word-nonword pairs (noon noof), orthographically similar nonwords (glome glame), and identical repetitions (plass plass). More RB was found for words than for nonwords. Prior researchers may have failed to find RB for nonwords because display conditions that allow 2 words to be reliably encoded are insufficient for nonwords, or because observers coped with low ability to encode nonwords by using guessing strategies that do not require creating a mental type or tokenizing it. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
79.
Lateralized readiness potentials (LRPs) were used to determine the stage(s) of reaction time (RT) responsible for speed-accuracy trade-offs (SATs). Speeded decisions based on several types of information were examined in 3 experiments, involving, respectively, a line discrimination task, lexical decisions, and an Erikson flanker task. Three levels of SAT were obtained in each experiment by adjusting response deadlines with an adaptive tracking algorithm. Speed stress affected the duration of RT stages both before and after the start of the LRP in all experiments. The latter effect cannot be explained by guessing strategies, by variations in response force, or as an indirect consequence of the pre-LRP effect. Contrary to most models, it suggests that SAT can occur at a late postdecisional stage. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
80.
At times the laws under which psychologists function may appear to contradict generally recognized ethical values and/or good clinical care. When these circumstances arise, psychologists must determine if a conflict really exists and, if so, seek solutions that reconcile respect for the law with their ethical values. At times, psychologists may decide to follow the law despite their ethical concerns. At other times, they may determine that a conscientious objection is warranted. The authors recommend options to consider when these situations arise and offer a decision-making process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  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