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   1106篇
  免费   31篇
  国内免费   2篇
电工技术   10篇
化学工业   219篇
金属工艺   2篇
机械仪表   19篇
建筑科学   9篇
矿业工程   1篇
能源动力   19篇
轻工业   3篇
石油天然气   2篇
无线电   112篇
一般工业技术   168篇
冶金工业   454篇
原子能技术   13篇
自动化技术   108篇
  2022年   15篇
  2021年   28篇
  2019年   14篇
  2018年   14篇
  2017年   18篇
  2016年   17篇
  2015年   11篇
  2014年   16篇
  2013年   25篇
  2012年   28篇
  2011年   36篇
  2010年   34篇
  2009年   20篇
  2008年   21篇
  2007年   24篇
  2006年   29篇
  2005年   37篇
  2004年   16篇
  2003年   23篇
  2002年   14篇
  2001年   15篇
  2000年   17篇
  1999年   25篇
  1998年   105篇
  1997年   67篇
  1996年   53篇
  1995年   26篇
  1994年   29篇
  1993年   33篇
  1992年   18篇
  1991年   19篇
  1990年   18篇
  1989年   20篇
  1988年   15篇
  1987年   18篇
  1986年   8篇
  1985年   12篇
  1984年   9篇
  1983年   12篇
  1982年   21篇
  1981年   8篇
  1980年   10篇
  1979年   10篇
  1978年   11篇
  1977年   18篇
  1976年   21篇
  1975年   8篇
  1974年   9篇
  1973年   13篇
  1966年   8篇
排序方式: 共有1139条查询结果,搜索用时 15 毫秒
991.
Autocrine stimulation of the type I insulin-like growth factor receptor (IGF-IR) by IGF-II is one mechanism that allows cancer cells to maintain unregulated growth and to resist programmed cell death (PCD). SH-SY5Y and SHEP cells are cloned human neuroblastoma (NBL) lines originating from a single primary tumor. SH-SY5Y cells, which express abundant cell surface IGF-IR and produce IGF-II, exhibit serum independent growth and resist PCD due to hypoxia and hyperosmolar conditions. In contrast, SHEP cells, which produce no IGF-II and express five-fold fewer IGF-IRs, die in serum-free media or following exposure to metabolic stressors. To better understand the roles of IGF-IR and its ligand, IGF-II, in NBL carcinogenesis, we stably transfected SHEP cells with either IGF-II or IGF-IR. Unregulated expression of IGF-II did not alter the growth characteristics of SHEP/human IGF-II transfectants. In contrast, overexpression of IGF-IR allowed SHEP/IGF-IR transfectants to survive in media supplemented only by IGF-II. IGF-IR abundance correlated in a graded fashion with resistance to PCD in response to three different death-inducing paradigms: mitogen withdrawal, hyperosmolar metabolic stress, and treatment with etoposide. Our results suggest that adjuvant therapy aimed at reducing IGF-IR abundance may enhance chemotherapy-coupled apoptosis in the treatment of NBL.  相似文献   
992.
OBJECTIVE: To identify and synthesise the findings from all randomised controlled trials that have examined the effectiveness of treatments of patients who have deliberately harmed themselves. DESIGN: Systematic review of randomised controlled trials of psychosocial and physical treatments. Studies categorised according to type of treatment. When there was more than one investigation in a particular category a summary odds ratio was estimated with the Mantel-Haenszel method. SETTING: Randomised trials available in electronic databases in 1996, in the Cochrane Controlled Trials Register in 1997, and from hand searching of journals to 1997. SUBJECTS: Patients who had deliberately harmed themselves shortly before entry into the trials with information on repetition of behaviour. The included trials comprised 2452 randomised participants with outcome data. MAIN OUTCOME MEASURE: Repetition of self harm. RESULTS: 20 trials reported repetition of self harm as an outcome variable, classified into 10 categories. Summary odds ratio (all for comparison with standard aftercare) indicated reduced repetition for problem solving therapy (0.73; 95% confidence interval 0.45 to 1.18) and for provision of an emergency contact card in addition to standard care (0.45; 0.19 to 1.07). The summary odds ratios were 0.83 (0.61 to 1.14) for trials of intensive aftercare plus outreach and 1.19 (0.53 to 2.67) for antidepressant treatment compared with placebo. Significantly reduced rates of further self harm were observed for depot flupenthixol versus placebo in multiple repeaters (0.09; 0.02 to 0.50) and for dialectical behaviour therapy versus standard aftercare (0.24; 0.06 to 0.93). CONCLUSION: There remains considerable uncertainty about which forms of psychosocial and physical treatments of patients who harm themselves are most effective. Further larger trials of treatments are needed.  相似文献   
993.
994.
995.
To compare children's socialized behavior to parents and non-parental agents, this study examined self-regulated compliance to mothers and caregivers--an early form of internalization--in 90 toddlers, half of whom were also observed with fathers. Adults were observed in play, teaching, and discipline sessions with the child and were interviewed on child-rearing philosophies. Child cognition and emotion regulation were assessed, and naturalistic observations were conducted at child-care locations. Mean-level and rank-order stability were found in child compliance to the 3 adults. Child emotion regulation and adult warm control in a discipline situation were related to self-regulated compliance to the mother, caregiver, and father. Compliance to parents correlated with parental sensitivity and philosophies, and compliance to the caregiver correlated with child cognition and social involvement when child-care quality was controlled. Maternal sensitivity and warm control discipline predicted compliance to the caregiver but not vice versa. Results are consistent with theoretical positions on the generalization of socialization from the mother to non-maternal agents. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
996.
997.
The design and use of fixed partial dentures as a definitive restoration to stabilize and splint teeth have been reviewed. The provisionalization of the splinted patient has been described as it is incorporated into the treatment plan of patients with a weakened periodontium. The current controversy of incorporating implants in the patient requiring splinting was discussed, and recommendations are made. Dentists are encouraged to explain all potential ramifications of splinting with fixed partial dentures, including cost, frequency of office visits, and potential alterations or remakes of the prosthesis should physiologic demands surpass the capabilities of the remaining teeth.  相似文献   
998.
Characteristics of the initial condensate in the recent experiment on Bose-Einstein condensation (BEC) of 87Rb atoms in an anisotropic magnetic trap are discussed. Given the aspect ratio R, the quality of BEC is estimated. A simple analytical ansatz for the initial condensate wave function is proposed as a function of the aspect ratio which, in contrast to the Baym-Pethick trial wave function, can be used for any interaction strength, reproduces both the weak and the strong interaction limits, and which is in better agreement with numerical results than the latter.  相似文献   
999.
1000.
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