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   2317篇
  免费   9篇
电工技术   1篇
综合类   1篇
化学工业   60篇
金属工艺   23篇
机械仪表   21篇
建筑科学   13篇
矿业工程   4篇
能源动力   4篇
轻工业   33篇
水利工程   7篇
无线电   52篇
一般工业技术   184篇
冶金工业   1874篇
自动化技术   49篇
  2023年   4篇
  2022年   7篇
  2020年   8篇
  2019年   6篇
  2018年   7篇
  2016年   9篇
  2015年   6篇
  2014年   6篇
  2013年   17篇
  2012年   11篇
  2011年   17篇
  2010年   10篇
  2009年   11篇
  2008年   17篇
  2007年   34篇
  2006年   24篇
  2005年   25篇
  2004年   20篇
  2003年   22篇
  2002年   14篇
  2001年   14篇
  2000年   10篇
  1999年   88篇
  1998年   624篇
  1997年   312篇
  1996年   226篇
  1995年   140篇
  1994年   120篇
  1993年   120篇
  1992年   6篇
  1991年   32篇
  1990年   31篇
  1989年   16篇
  1988年   32篇
  1987年   15篇
  1986年   22篇
  1985年   13篇
  1984年   7篇
  1983年   4篇
  1982年   12篇
  1981年   20篇
  1980年   13篇
  1979年   4篇
  1978年   9篇
  1977年   44篇
  1976年   87篇
  1975年   5篇
  1974年   3篇
  1970年   3篇
  1967年   2篇
排序方式: 共有2326条查询结果,搜索用时 15 毫秒
61.
Explaining a knowledge system's conclusions requires, among other things, showing how it has satisfied the logical requirements of its problem-solving task. In one report it was shown how task-based explanation worked in generic tasks (GT); other GT work showed how more complex tasks could be solved using multiple GT modules. Because each GT in a composite GT knowledge system serves a role defined by the higher-level goals it serves (i.e., a GT module is a method that achieves a particular goal of the higher-level task) it is possible to explain the high-level task in terms of the low-level GT explanations. We have introduced the idea of a logical structure for diagnosis, a task solved by composition of several GTs, and its use in explanation. In this article we describe how these ideas work to generate explanations in a composite GT system.  相似文献   
62.
In labeling pay or money as a “mere” hygiene factor, Frederick Herzberg set off a controversy that has continued up to the present by asking: Does money matter? Our study, involving several hundred I/S graduates over a four-year period, measures the importance of “above-average salaries” to these graduates as they progress through the early months of their I/S careers. Initially, salary is ranked highly; but as time passes, other factors tend to crowd out salary in importance. It loses its role as a motivator; and, as Herzberg suggests, becomes a hygiene factor.  相似文献   
63.
OBJECTIVE: To describe assisted reproductive technology (ART) and use of medications during these procedures. DATA SOURCES: Recent clinical literature. STUDY SELECTION: Not applicable. DATA EXTRACTION: Not applicable. DATA SYNTHESIS: ARTs are procedures used in treatment of infertility that involve removal of oocytes and their manipulation outside the woman's uterus. The simplest form of ART, in vitro fertilization, involves aspirating eggs from the ovaries, fertilizing them outside the body, and transferring the embryos into the uterus at the four- to eight-cell stage. Experimental regimens for in vitro fertilization include use of various medications (gonadotropin-releasing hormone agonists, human menotropins, follicle-stimulating hormone, growth hormone) at varying points in the menstrual cycle and after introduction of the embryo into the uterus. Human chorionic gonadotropin has been used to increase implantation of embryos during the woman's luteal phase. Gamete intrafallopian transfer (GIFT) involves transfer of oocytes and sperm into the fallopian tubes, where fertilization takes place. This technique has the advantage of causing the zygote to enter the uterus at the time it would during natural conception. Zygote intrafallopian transfer is similar to GIFT, except that fertilization occurs in vitro, with embryos placed in the fallopian tubes at the two-cell stage. Various micromanipulation techniques and innovative sperm aspiration procedures are currently under development. CONCLUSION: Many advancements have been made in ART, and pharmacists who understand these procedures can serve patients by providing medication information in an empathetic and supportive manner.  相似文献   
64.
65.
Combination therapy with intravesical bacillus Calmette-Guérin (BCG) plus IFN-alpha for superficial bladder cancer has been demonstrated to be more effective than either single agent alone in animal studies and of suggested greater efficacy in clinical studies. However, the mechanism by which IFN-alpha enhances BCG-mediated antitumor activity is poorly understood. Using PBMCs from bladder cancer patients, IFN-alpha was found to substantially enhance the efficacy of BCG to induce IFN-gamma production. Among 34 patients tested, 80% showed >4-fold increase. This effect of IFN-alpha was observed in both initial and memory responses to BCG. In addition, IFN-alpha up-regulated BCG-induced IL-12 and TNF-alpha and down-regulated BCG-induced IL-10. Neutralizing endogenous IL-10 or adding exogenous IL-12 provided further synergy for IFN-gamma production. In clinical practice, intravesical IFN-alpha 2B (50 million units (MU)/dose) was observed to accelerate urinary IFN-gamma production to low-dose BCG (one-tenth or one-third of a full dose) in patients treated with combination therapy compared with BCG alone. These results suggest that IFN-alpha is a potent BCG enhancer that polarizes the BCG-induced immune response toward the cellular immune pathway by promoting Th1 cytokine expression and reducing Th2 cytokine expression. This study provides an immunological basis for future rational use of IFN-alpha in conjunction with intravesical BCG for bladder cancer immunotherapy.  相似文献   
66.
67.
68.
We have developed a new detection method for measuring distributions of energy depositions from particles characterized by low linear energy transfers (LETs). In particular, we have developed a detection system to measure energy depositions produced by electrons and photons on nanometer scales. The detector is based upon the operational principles of the superheated drop detector (SDD). SDDs consist of tiny droplets of superheated liquid suspended within a gel-like emulsion. The SDDs in this study are fabricated using Freon-115 and a glycerol-based gel as the superheated liquid and host medium. This SDD configuration is operated as a threshold temperature-dependent detector for measuring nanoscopic distributions of energy depositions from low-LET particles. Measured results are compared to the calculated distributions of energy depositions along an electron track. A new electron track code, ESLOW3.1, is used to perform the computational study. Measurements show good agreement with computational results in the energy deposition range of 40-200 eV.  相似文献   
69.
70.
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