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   1553篇
  免费   1篇
  国内免费   1篇
电工技术   2篇
综合类   1篇
化学工业   49篇
金属工艺   6篇
机械仪表   4篇
建筑科学   5篇
能源动力   1篇
轻工业   22篇
石油天然气   3篇
无线电   14篇
一般工业技术   19篇
冶金工业   1404篇
原子能技术   7篇
自动化技术   18篇
  2014年   2篇
  2013年   8篇
  2012年   2篇
  2011年   4篇
  2010年   3篇
  2009年   7篇
  2007年   4篇
  2006年   3篇
  2005年   6篇
  2004年   3篇
  2003年   8篇
  2002年   15篇
  2001年   3篇
  2000年   4篇
  1999年   38篇
  1998年   463篇
  1997年   278篇
  1996年   148篇
  1995年   101篇
  1994年   62篇
  1993年   85篇
  1992年   11篇
  1991年   28篇
  1990年   31篇
  1989年   26篇
  1988年   31篇
  1987年   15篇
  1986年   16篇
  1985年   10篇
  1984年   2篇
  1983年   6篇
  1982年   6篇
  1981年   9篇
  1980年   15篇
  1979年   2篇
  1978年   8篇
  1977年   19篇
  1976年   44篇
  1975年   4篇
  1974年   4篇
  1973年   3篇
  1972年   3篇
  1971年   2篇
  1966年   1篇
  1963年   1篇
  1957年   1篇
  1944年   1篇
  1941年   1篇
  1940年   2篇
  1920年   1篇
排序方式: 共有1555条查询结果,搜索用时 9 毫秒
101.
102.
Overcoming denial and admitting to having a chemical dependency problem is a hurdle that is extraordinarily difficult for anyone to handle without professional assistance. Addicted health care professionals often become even more deeply enmeshed in denial of their problem. They refuse help because they see themselves as educated beyond the level of those who are attempting to help them, and because they fear professional humiliation. Dental professionals who become aware of a colleague's chemical dependence, have an ethical duty to intervene in a constructive way. Reporting to a dental society wellness committee will accomplish this goal while protecting patients, the profession, the addicted provider, and the provider's family. Nonetheless, assisting chemically dependent colleagues to seek treatment can be an enormous burden. Thus, the dental hygienist in the case presented has few choices. She clearly has sufficient evidence of the dentist's chemical dependency problem and, ethically, she must act to prevent harm to patients. If a wellness program is available, it will help her. However, she should not expect gratitude from the dentist at the time of her intervention. Addicted persons rarely thank those who try to help them until much later and whistle-blowers are rarely appreciated. As is often the case, doing the right thing may be a challenge that risks losing a relationship or, as in the case presented, a job.  相似文献   
103.
104.
105.
Systems used in complex, multi-agency environments have a number of inherent problems and challenges that in many cases, lead to systems failure. The area of system failure has been the subject of extensive research in the past. It has been well documented in a number of places that information systems are difficult to build and are prone to failure. This paper examines system failure from a social perspective in the context of building systems in complex environments. Through a case study modelling approach, a framework has been developed to assist in building information systems in such complex multi-agency environments. The paper introduces this framework through a study of a number of challenges confronting the builder of information systems in complex, social, multi-agency environments. We examine the role of task accountability and problems identifying authority as key reasons why systems are rejected by users. We introduce a task accountability model to help understand this problem. We conclude by identifying work still to be carried out within the study.  相似文献   
106.
The author discusses the influence of depth on the transmission of narrow slots and presents curves of calculated and measured transmission that exhibit depth resonances. The measurements are made by illuminating the front face of an aluminum box that is 50 cm on each side. At these resonances, the transmission is shown to be much higher than predicted by zero-depth models  相似文献   
107.
108.
BACKGROUND: Whether or not tumor response to chemotherapy-sensitized radiation therapy (CTRT) for head and neck cancer leads to an improved outcome is unknown. METHODS: Forty patients who received preoperative cisplatin plus simultaneous radiotherapy for operable stage III and IV head and neck cancer were reviewed retrospectively regarding clinical demographics, staging, and survival status. RESULTS: Twenty-one (57%) patients had a histologic complete response (HCR) and 16 (43%) had a partial (PR) (9) or clinical complete (7) response (CCR). Tumor response of N1 versus N2-3 nodal disease showed 6 (75%) HCR and 4 (25%). Five-year disease-free survival overall was 82% for HCR versus 38% for PR/CCR (P <0.05). Disease-specific 5-year survival was 100% for HCR versus 27% for PR/CCR (P <0.002). CONCLUSIONS: Histologic complete response to CTRT for head and neck cancer is associated with increased survival and encouraging disease-free status. Response to CTRT is inversely proportional to lymphatic tumor load.  相似文献   
109.
By direct sequencing of cosmids using primers designed from the known cDNA sequence, we identified 19 exons in the human MET proto-oncogene, and sequenced the corresponding 5' and 3' exon-intron junctions. By homology search in the database of the Washington University Genome Sequence Center (GSC), we identified one additional exon. These 20 exons, together with a previously reported exon, bring the total exon number of MET to 21. Oligonucleotide primers were designed to amplify each exon and adjacent intronic sequences to permit examination of each exon for mutations. By restriction mapping, we assembled a 110 kb genomic contig that covered almost the entire MET proto-oncogene. This information is relevant for the screening of recently reported mutations of the MET gene which cause hereditary papillary renal carcinomas and for the search for additional mutations of the same gene which may play a role in the pathogenesis of common human carcinomas including carcinomas of the breast, ovary and pancreas.  相似文献   
110.
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