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   544篇
  免费   2篇
电工技术   3篇
综合类   2篇
化学工业   30篇
金属工艺   31篇
机械仪表   12篇
建筑科学   2篇
矿业工程   2篇
能源动力   5篇
轻工业   9篇
水利工程   4篇
石油天然气   9篇
无线电   13篇
一般工业技术   71篇
冶金工业   300篇
原子能技术   24篇
自动化技术   29篇
  2021年   10篇
  2019年   4篇
  2018年   3篇
  2017年   6篇
  2016年   6篇
  2014年   6篇
  2013年   8篇
  2012年   10篇
  2011年   18篇
  2010年   11篇
  2009年   8篇
  2008年   12篇
  2007年   16篇
  2006年   5篇
  2005年   9篇
  2004年   3篇
  2003年   9篇
  2002年   3篇
  2001年   8篇
  2000年   3篇
  1999年   14篇
  1998年   70篇
  1997年   42篇
  1996年   46篇
  1995年   28篇
  1994年   21篇
  1993年   18篇
  1991年   8篇
  1990年   7篇
  1989年   4篇
  1988年   3篇
  1987年   6篇
  1986年   3篇
  1985年   4篇
  1984年   3篇
  1982年   2篇
  1981年   11篇
  1980年   8篇
  1979年   5篇
  1978年   5篇
  1977年   12篇
  1976年   17篇
  1975年   9篇
  1974年   6篇
  1973年   6篇
  1972年   2篇
  1971年   4篇
  1970年   3篇
  1968年   7篇
  1965年   2篇
排序方式: 共有546条查询结果,搜索用时 29 毫秒
1.
2.
Attachment between parent and child plays a crucial role in the healthy development of the child. Accordingly disturbances in parental bonding will be linked with the development of mental disorders later in life. The present study examines the relationship between parental bonding and mental health in healthy adolescents. Participants were 847 Israeli high school students who completed the Parental Bonding Instrument (PBI), the Brief Symptom Inventory (BSI), the General Well-Being (GWB), the Perceived Social Support (PSS), and the Social Desirability scale (SDS). In general, Israeli adolescents reported more parental care and less control than did Australian adolescents and adults. Female subjects reported more maternal care than did males. Subjects who reported high care and low control (optimal bonding) reported less distress, better general well-being and better social support that did all other groups. In contrast, those who reported low care and high control (affectionless control bonding) had the highest BSI scores and the lowest GWB and PSS scores. These results are in line with Bowlby's theory of attachment. They also show that specific configuration of parental bonding are linked with distress and isolation in adolescents.  相似文献   
3.
Phospholipid transfer protein (PLTP) was purified from lipoprotein-free human plasma, obtained upon treatment of plasma with dextran sulfate and Ca2+, by employing a series of column chromatography. Upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the purified PLTP showed a single main band, corresponding to the molecular mass of 78 kDa. However, isoelectric focusing of the purified preparation gave multiple bands with pI ranging from 4.3 to 5.1, indicative of microheterogeneity. Purified PLTP was shown to possess not only phospholipid transfer activity, but also high density lipoprotein (HDL) conversion activity (Tu, A.-Y., Nishida, H. I., and Nishida, T. (1990), FASEB J. 4, A2148; Jauhiainen, M., Metso, J., Pahlman, R., Blomqvist, S., van Tol, A., and Ehnholm, C. (1993) J. Biol. Chem. 268, 4032-4036). Isolated HDL3 was enlarged to the size of HDL2b upon incubation with purified PLTP for 6 h at 37 degrees C at the PLTP/HDL3 molar ratio of approximately 1:45. Both the HDL conversion and the phosphatidylcholine transfer activities of purified PLTP were effectively inhibited by rabbit anti-PLTP immunoglobulin G. The primary importance of PLTP in the HDL enlargement that occurs in human plasma upon incubation at 37 degrees C was shown by the strong inhibitory effect of the anti-PLTP immunoglobulin G. The process of PLTP-mediated HDL enlargement was accompanied by the release of apoproteins, primarily apoA-I. HDL3 enlargement mediated by PLTP was effectively inhibited by the addition of free fatty acids.  相似文献   
4.
5.
6.
7.
We present a method for unified statistical analysis of short and long range correlations between various nucleotides in genomic DNA strands. The approach is based on the mutual study of Fourier structure factor spectra and pair correlation functions. The analysis of cross correlations in the different ranges of structural spectra permits identification of the main sources of correlations, namely, the coherent point mutations, coincident periodicities or large scale density variations. The technique for assessment of structural coupling between various genes in the genome is also described.  相似文献   
8.
The dynamics and present state of the radioactive contamination with 137Cs of littoral soil of Lake Kozhanovskoe and Lake Svyatoe on the Besed’ River are presented. The parameters of the vertical migration of 137Cs in soil-the rate of directional transfer with soil moisture, the diffusion coefficient, and the average velocity of vertical migration-are estimated by comparing the experimental and model distributions of 137Cs content over soil depth. It is shown that at the present time the two 5-cm layer of soil can contain 20–90% 137Cs depending on the type of soil and landscape. The average values of the diffusion coefficient, the rate of directional transfer, and the vertical migration velocity for 12-, 13-, and 20-year periods after the Chernobyl accident are 0.1–2.8 cm2/yr, 0.1–0.3 cm/yr, and 0.1–0.8 cm/yr, respectively. __________ Translated from Atomnaya énergiya, Vol. 102, No. 5, pp. 306–311, May, 2007.  相似文献   
9.
Most software engineering courses require students to develop small programs from scratch, but professional engineers typically work on the evolution of large software systems. Using open source software and a software change process model can narrow this gap without imposing excessive demands on students or instructors.  相似文献   
10.
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