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   3381篇
  免费   140篇
  国内免费   20篇
电工技术   145篇
综合类   3篇
化学工业   554篇
金属工艺   78篇
机械仪表   61篇
建筑科学   162篇
矿业工程   10篇
能源动力   100篇
轻工业   385篇
水利工程   21篇
石油天然气   18篇
武器工业   1篇
无线电   348篇
一般工业技术   409篇
冶金工业   441篇
原子能技术   30篇
自动化技术   775篇
  2023年   13篇
  2022年   44篇
  2021年   64篇
  2020年   38篇
  2019年   58篇
  2018年   113篇
  2017年   85篇
  2016年   77篇
  2015年   72篇
  2014年   114篇
  2013年   253篇
  2012年   208篇
  2011年   169篇
  2010年   201篇
  2009年   210篇
  2008年   240篇
  2007年   160篇
  2006年   178篇
  2005年   159篇
  2004年   92篇
  2003年   116篇
  2002年   102篇
  2001年   58篇
  2000年   67篇
  1999年   63篇
  1998年   85篇
  1997年   65篇
  1996年   53篇
  1995年   41篇
  1994年   34篇
  1993年   33篇
  1992年   27篇
  1991年   23篇
  1990年   26篇
  1989年   26篇
  1988年   13篇
  1987年   13篇
  1986年   17篇
  1985年   10篇
  1984年   13篇
  1983年   18篇
  1982年   11篇
  1981年   13篇
  1980年   13篇
  1979年   7篇
  1978年   8篇
  1977年   8篇
  1976年   13篇
  1974年   4篇
  1967年   3篇
排序方式: 共有3541条查询结果,搜索用时 15 毫秒
21.
22.
A unified single-equation approach for the MOS transistordrain current modeling for energy-efficient submicron MOS circuitsis presented. Instead of three sets of separate equations forthe triode, saturation, and weak inversion regions, only a continuousexpression which is valid to describe the behavior of drain currentand the derivatives in all operation regions can be realizedby using a combination of hyperbola, sigmoid, and interpolationmethods. The model expression can predict accurate results forthe current, output conductance, and transconductance with continuousand smooth characteristics. The simulation results agree wellwith experimental data.  相似文献   
23.
Steve M. Cohn 《Energy》1980,5(12):1203-1212
The energy demand response of the residential and commercial sectors to fuel price changes is of increasing importance to public policy makers. In this paper, the demands for energy in both sectors are examined separately using a refined data base. For each sector, a multinomial logit formulation is utilized, along with an aggregate demand equation to determine analytically short- and long-run fuel price elasticities of demand for the major fuels consumed. It is found that increases in energy prices have a greater effect on energy demand in the commercial sector. Furthermore, in both sectors, raising electricity prices has a greater effect for conserving energy (both end-use and primary) than do equal price rises for natural gas or heating oils.  相似文献   
24.
行业分析人士曾预测,蓝牙半导体市场会在2000年下半年开始攀升,而在2001年将持续攀升.尽管这些预测未达到期待的水平,但普遍地持乐观的态度,蓝牙技术有吸引力的市场仍在向我们召唤.对这一变幻无常的市场,很多半导体供应商趁修改和更新标准之际,纷纷改变了蓝牙产品研发计划.  相似文献   
25.
Investigated whether (1) feminist identity development for women therapists was related to their use of feminist therapy behaviors (FTBs) and (2) feminist identity development and use of FTBs for women therapists were related to self-identification as a feminist therapist. 153 women psychologists (aged 30–77 yrs) were administered a women's issues in therapy questionnaire, which included a short version of the Feminist Identity Scale (FIS; K. M. Rickard, 1989, 1990). Ss were categorized into stages of feminine identity development according to their scores on 4 subscales of the FIS: Passive-Acceptance (PA), Revelation (REV), Embeddedness (EMB), and Synthesis (SYN). Ss scoring high on SYN and REV, and low on PA, reported greater use of FTBs; scores on the EMB were not related to the use of FTBs. All 4 subscales were predictive of women therapists who self-identified as feminist therapists. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
26.
This report reviews the analysis used to extract the complex conductivity of a compound from a microwave cavity perturbation measurement. We intend to present a generalized treatment valid for any spheroidally shaped sample of arbitrary conductivity which is placed at either the electric or magnetic field antinode of the cavity. To begin with, we establish the relationship between the measured parameters and the conductivity for a spherical sample. Next, we extend these results to the case of spheroids; and for the first time, we cover all different configurations that one can possibly use to study an arbitrary conducting sample inside a cavity: in particular, all possible orientations of the sample with respect to the applied field are solved.  相似文献   
27.
运行在869MHz-2.17GHz频段内的蜂窝无线基站是射频功率晶体替如今最大的市场。其中,基中硅的LDMOS器件被广泛使用于500MHz=2.5GHz之间的射频功率放大器应用当中。作为增强模式的N沟道MOSFET,LDMOS器件(LD代表侧面扩散,描述了器件的沟道结构)专门被设计成为具有高的工作电压(长沟道)和低寄生电容,从而能在高频下工作。在早  相似文献   
28.
Suggests that detecting memory impairment with the modified test relies on long retention intervals that provide the necessary forgetting of event information for impairing effects of postevent misinformation to occur. 288 Ss were tested in 4 experiments that presented event items centrally, introduced verbal postevent items to a misled condition, and used the modified test, but differed by using either short (15 min) or long (5–7 days) retention intervals. As evidenced by poorer misled than control test performances, memory impairment only occurred with long retention intervals. Retrieval- and storage-based versions of memory-impairment hypotheses are assessed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
29.
Notes that an extensive network of empirical relations has been identified in research on the psychological construct of self-monitoring. Nevertheless, in recent years some concerns have been expressed about the instrument used for the assessment of self-monitoring propensities, the Self-Monitoring Scale (SMS) developed by the 1st author (see record 1975-03047-001). Both the extent to which the SMS taps an interpretable and meaningful causal variable and the extent to which the self-monitoring construct provides an appropriate theoretical understanding of this causal variable have been questioned. An examination of reanalyses of studies of self-monitoring, analyses of the internal structure of the SMS, and further relevant data suggests that the measure does tap a meaningful and interpretable causal variable with pervasive influences on social behavior, a variable reflected as a general self-monitoring factor. The evaluation and furthering of the interpretation of this latent causal variable are discussed, criteria for evaluating alternative measures of self-monitoring are offered, and a new 18-item SMS is presented. (88 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
30.
Dynamic Policy-Based Network Management for a Secure Coalition Environment   总被引:1,自引:0,他引:1  
This article reports the latest results of an R&D effort to develop a prototype implementation of a dynamic policy-based network management (PBNM) system that can be used to configure and manage a secure network for a coalition environment across an unsecured wide area network. The prototype, based on a distributed architecture, includes capabilities for policy creation and management, dynamic policy negotiation, and dynamic policy provisioning. The policy negotiation facilitates the rapid deployment of a coalition network while the dynamic policy provisioning automates the configuration and management of network services including firewalls, virtual private network connections, routing, quality of service (QoS), and domain name services. Such a PBNM system enhances an organization's ability to react to network incidents identified by a network situational awareness assessment. Although the focus of the current research is a military coalition environment, the system can be used in any distributed enterprise or collaborative environment  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