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   6723篇
  免费   223篇
  国内免费   4篇
电工技术   63篇
综合类   1篇
化学工业   1090篇
金属工艺   89篇
机械仪表   101篇
建筑科学   267篇
矿业工程   9篇
能源动力   152篇
轻工业   613篇
水利工程   44篇
石油天然气   8篇
无线电   494篇
一般工业技术   1009篇
冶金工业   2078篇
原子能技术   49篇
自动化技术   883篇
  2022年   73篇
  2021年   101篇
  2020年   60篇
  2019年   79篇
  2018年   110篇
  2017年   113篇
  2016年   83篇
  2015年   97篇
  2014年   141篇
  2013年   326篇
  2012年   206篇
  2011年   294篇
  2010年   229篇
  2009年   249篇
  2008年   242篇
  2007年   257篇
  2006年   216篇
  2005年   197篇
  2004年   180篇
  2003年   172篇
  2002年   187篇
  2001年   141篇
  2000年   146篇
  1999年   159篇
  1998年   376篇
  1997年   238篇
  1996年   219篇
  1995年   156篇
  1994年   146篇
  1993年   138篇
  1992年   98篇
  1991年   67篇
  1990年   80篇
  1989年   94篇
  1988年   83篇
  1987年   83篇
  1986年   62篇
  1985年   65篇
  1984年   90篇
  1983年   76篇
  1982年   70篇
  1981年   68篇
  1980年   66篇
  1979年   68篇
  1978年   50篇
  1977年   63篇
  1976年   102篇
  1975年   50篇
  1974年   41篇
  1972年   29篇
排序方式: 共有6950条查询结果,搜索用时 250 毫秒
71.
72.
73.
The utilization of a physician critique process in the design of a parenteral nutrition order form, encouraging a standard order option, is assessed. In the critique process, physicians from surgery, medicine, and medical intensive care teams were tasked to use the draft order form and guideline sheet to prescribe a parenteral nutrition order for a hypothetical patient. Prescriber recommendations and problems with the nutrition order form and guideline sheet directed editorial improvements. The physician assessment process is an effective means to measure utility of a draft parenteral order form and prescribing guideline sheet. By utilizing physician expertise, deficiencies inherent in such an order form may be corrected prior to implementation.  相似文献   
74.
Retail samples of livers from calf (23), ox (18), lamb (17), pig (15), chicken (16) and turkey (1) were analysed to determine levels of vitamin A (all trans-retinol) and to aid assessment of the effects of using vitamin supplemented compound feedingstuffs for livestock. For comparison, 22 liver samples from lambs reared on diets not containing vitamin-supplemented compound feedingstuffs and four samples of liver from ox which had received supplemented feed but not during the last four months prior to slaughter were also analysed. The chosen method of analysis utilized saponification, solvent extraction and normal-phase high performance liquid chromatography with fluorescence detection. For all species analysed, the levels of vitamin A ranged from 10 to 1100 mg/kg, with all but seven at or below 400 mg/kg. For lamb and ox livers, the mean levels were 310 mg/kg and 200 mg/kg respectively for retail samples. The mean levels were 220 mg/kg (lamb) and 120 mg/kg (ox) in liver samples from animals fed controlled diets. The results are of the same order as those reported over recent years.  相似文献   
75.
Survivors of sexual abuse enter psychotherapy with special needs that challenge some of the traditional therapeutic assumptions. The therapeutic relationship, which is the foundation for treatment with abuse survivors, often must shift in nature and quality to address these needs. The main goal of treatment is the integration of self and affective experience. To facilitate this process the authors discuss the establishment and maintenance of an "affective edge" that allows for direct attention to and intervention with the trauma memories and the accompanying affect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
76.
Addressed conflicting views of depressives' interpersonal accuracy in an investigation of the accuracy of mild depressives (dysphorics) across differing social contexts. Women who were either friends or strangers and who were either similar or dissimilar in level of dysphoria conversed about 3 topics: a neutral topic, their own disclosure of a personal problem, and their partner's disclosure. Dysphorics were not more accurate in general than nondysphorics. After self-disclosure, all women more accurately detected sympathy from a similar stranger. After the partner's disclosure, women also better detected the mood of a similar partner. When interacting with nondysphoric strangers, however, dysphorics underestimated their partner's sympathy toward them. Implications for cognitive and interpersonal theories of depression and for depressives' relationships are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
77.
It was proposed that thinking about disease-detection behavior would lead to more negative moods than thinking about health-promotion behavior. Detection behaviors produce more negative moods because they can threaten perceptions of good health. In a laboratory study, the initial mood states of 121 participants recruited from undergraduates and the general community were measured using a neutral-words rating procedure. Then participants were randomly assigned to think about performing a disease-detection behavior or a health-promotion behavior. Subsequently, they wrote down their responses to the behavior and evaluated these 35 either positive, negative, or neutral. Finally, the participant's mood was remeasured using both a neutral words-rating procedure and a more traditional bipolar rating measure. Results indicated that thought about disease-detection behavior produced more negative affective responses and more negative mood change than did thought about health-promotion behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
78.
Introduction.     
This article introduces the current issue of Health Psychology. The call for early intervention to prevent adulthood health problems and the need to consider each period of children's lives within its developmental perspective are the main emphases in this special issue of the journal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
79.
The authors describe an integrated processor that performs addition and subtraction of 30-b numbers in the logarithmic number system (LNS). This processor offers 5-MOPS performance in 3-μm CMOS technology, and is implemented in a two-chip set comprising 170 K transistors. Two techniques are used to achieve this precision in a moderate circuit area. Linear approximation of the LNS arithmetic functions using logarithmic arithmetic is shown to be simple due to the particular functions involved. A segmented approach to linear approximation minimizes the amount of table space required. Subsequent nonlinear compression of each lookup table leads to a further reduction in table size. The result is that a factor of 285 reduction in table size is achieved, compared to previous techniques. The circuit area of the implementation is minimized by optimizing the table parameters, using a computer program that accurately models ROM area. The implementation is highly pipelined, and produces one result per clock cycle using a ten-stage pipeline  相似文献   
80.
The Modular High Temperature Gas-Cooled Reactor (MHTGR) is a candidate design for new production and commercial power nuclear reactors. The MHTGR has inherent safety features including: (1) passive shutdown and decay heat removal, (2) reduced requirements for operator intervention, thereby reducing sensitivity to operator error, and (3) long time intervals for corrective action. In support of the Department of Energy's (DOE) initial development of the design, the authors have completed an evaluation of the thermal-hydraulic phenomena that will dominate the plant response during representative normal, off-normal and accident conditions. Phenomena having significance to the plant behavior have been identified, and ranked with respect to their relative importance in satisfying operational, investment and/or safety criteria. The resulting information provides the basis for evaluating the applicability of existing computer codes, and defines the requirements for the development of new codes, for thermal-hydraulic systems analysis. The phenomena-based requirements also support the quality assurance related verification and validation of these codes. This paper briefly describes the methodology employed, and gives illustrative examples of the resulting requirements. References are cited for reports that document the full body of requirements and provide additional information for the methodology.  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