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   10270篇
  免费   66篇
  国内免费   5篇
电工技术   30篇
综合类   5篇
化学工业   346篇
金属工艺   37篇
机械仪表   35篇
建筑科学   58篇
矿业工程   2篇
能源动力   37篇
轻工业   165篇
水利工程   41篇
石油天然气   16篇
武器工业   1篇
无线电   154篇
一般工业技术   315篇
冶金工业   8865篇
原子能技术   16篇
自动化技术   218篇
  2023年   7篇
  2022年   14篇
  2021年   23篇
  2020年   12篇
  2019年   23篇
  2018年   36篇
  2017年   25篇
  2016年   39篇
  2015年   27篇
  2014年   58篇
  2013年   89篇
  2012年   82篇
  2011年   132篇
  2010年   91篇
  2009年   92篇
  2008年   108篇
  2007年   108篇
  2006年   104篇
  2005年   79篇
  2004年   67篇
  2003年   72篇
  2002年   62篇
  2001年   42篇
  2000年   43篇
  1999年   317篇
  1998年   2745篇
  1997年   1539篇
  1996年   998篇
  1995年   584篇
  1994年   454篇
  1993年   555篇
  1992年   84篇
  1991年   114篇
  1990年   121篇
  1989年   108篇
  1988年   102篇
  1987年   105篇
  1986年   102篇
  1985年   71篇
  1983年   16篇
  1982年   44篇
  1981年   45篇
  1980年   84篇
  1979年   11篇
  1978年   15篇
  1977年   189篇
  1976年   446篇
  1975年   13篇
  1973年   7篇
  1955年   7篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
Nasopharyngeal stenosis and oropharyngeal stenosis are rare and challenging problems in the pediatric population. The most common etiology is currently the surgical trauma associated with adenotonsillectomy. Stenosis can vary from a thin band to a complete obstructing cicatrix. Presenting symptoms range from mild hyponasal speech to severe airway obstruction. We present a series of eight children with varying degrees of stenosis and associated symptoms. Choice of treatment varied with the severity of disease. In our series, successful interventions included triamcinolone acetonide injection, lysis of adhesions, rotational and advancement mucosal flaps, and jejunal free flap. Preoperative evaluation and individualized surgical repair are essential for successful treatment.  相似文献   
122.
The stimulatory effect of phytin added to skim milk on acid production of Lactobacillus casei was examined. Phytin stimulated acid production of L. casei fairly well. The stimulatory effect of phytin on acid production was not shown when phytin was treated with Dowex 50 (H+) and neutralized by NaOH solution. The incinerated product of phytin maintained almost equal stimulatory effect on acid production as that before processing. The addition of Mn2+ in the amount contained in a reagent phytin augmented the stimulatory effect on acid production markedly. The further addition of Fe3+, Ca2+, Mg2+ and PO4(3-) in amounts corresponding to their contents in the preparation of phytin as well as Mn2+ increased the effect slightly. The four preparations of phytin contained 0.045-0.20% of Mn, and the greater the Mn content was, the greater the potentiation of acid production.  相似文献   
123.
124.
125.
Ornithine decarboxylase (ODC) has been shown to be oncogenic in transfected NIH/3T3 cells overexpressing the enzyme from a heterologous promoter. These cells, designated as NODC-2 cells, acquire proliferative properties associated with tumorigenic transformation such as loss of contact inhibition, decreased population doubling time, anchorage-independent growth, and tumor production in nude mice. At least one of these parameters, loss of contact inhibition, remains dependent on elevated ODC levels. We have used these cells to investigate the molecular mechanisms by which ODC overexpression drives cell transformation and to examine the involvement of other proto-oncogene products in this process. An interaction between ODC overexpression and the epidermal growth factor receptor (EGF-R) was suggested initially by the elevation of both basal (300%) and ligand-induced (457%) EGF-R tyrosine kinase activities in NODC-2 cells compared to similarly treated control NLK cells. Disruption of EGF-R mediated signal transduction in NODC-2 cells both by treatment with tyrphostin-25 or by transfection with a vector expressing a dominant negative EGF-R mutant resulted in reacquisition of contact-inhibited growth and suppression of anchorage-independent, clonogenic growth in soft agar. We conclude that ODC-induced transformation of NIH/3T3 cells is mediated, at least partly, by alterations in EGF-R signal transduction activity.  相似文献   
126.
127.
Based on successful results in animal models, it has been proposed that high-dose myeloablative therapy followed by autologous bone marrow or stem cell transplantation (ABMT/ASCT) may cure autoimmune disease. The coexistence of autoimmune disease and hematologic malignancy provides an opportunity to examine the response of autoimmune disease to ABMT or ASCT. We describe 4 patients with autoimmune disease (3 with psoriasis and 1 with rheumatoid arthritis) and hematologic malignancy. In each patient, the autoimmune disease remitted posttransplantation, but, in 4 patients with long-term followup, it recurred at 8-24 months. The earliest relapse occurred in a patient treated with interferon-alpha. Our experience suggests that a single autograft with unpurged stem cells is unlikely to cure autoimmune disease, but that other strategies building on this approach are worthy of investigation.  相似文献   
128.
Examined perceived environment, perceived incentive and outcome, and person constructs for relationships with interest and participation in voluntary learning and development activity by nonmanagement employees. All 3 groups of constructs were related to development activity. In relationships with development activity, perceived outcome and environment variables interacted with workers' personal values relevant to aspects of a development setting, illustrating the potentially important role that differences in values may play in a development context. Additionally, small relationships were observed between several demographic variables and values within a development setting. Results provide implications for the design and implementation of successful development programs and highlight the need to carefully consider individual differences in this context when targeting many different types of employees for participation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
129.
Responds to M. F. Hoyt's (see record 1995-22250-001) commentary on T. F. Van Denburg and E. J. Van Denburg's (see record 1994-18427-001) response to Hoyt's (see record 1994-18395-001) commentary on Van Denburg and Van Denburg's (see record 1993-06526-001) article about a case of premature therapy termination. Issues related to limits and flexibility in treatment are addressed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
130.
What can be done to preserve the high standards of patient care, give reasonable assurances to patients and acknowledge the rights of health care workers? Conscientious adherence to infection control is the most responsible option available.  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