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   46445篇
  免费   539篇
  国内免费   31篇
教育   33956篇
科学研究   4187篇
各国文化   328篇
体育   3179篇
综合类   28篇
文化理论   637篇
信息传播   4700篇
  2022年   228篇
  2021年   370篇
  2020年   548篇
  2019年   866篇
  2018年   3223篇
  2017年   3149篇
  2016年   2550篇
  2015年   760篇
  2014年   1026篇
  2013年   6865篇
  2012年   1167篇
  2011年   1679篇
  2010年   1492篇
  2009年   1083篇
  2008年   1443篇
  2007年   1810篇
  2006年   770篇
  2005年   957篇
  2004年   957篇
  2003年   853篇
  2002年   661篇
  2001年   737篇
  2000年   646篇
  1999年   572篇
  1998年   316篇
  1997年   360篇
  1996年   386篇
  1995年   387篇
  1994年   309篇
  1993年   343篇
  1992年   508篇
  1991年   476篇
  1990年   468篇
  1989年   496篇
  1988年   451篇
  1987年   461篇
  1986年   426篇
  1985年   476篇
  1984年   397篇
  1983年   408篇
  1982年   333篇
  1981年   305篇
  1980年   292篇
  1979年   441篇
  1978年   340篇
  1977年   300篇
  1976年   284篇
  1975年   246篇
  1974年   251篇
  1973年   237篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
982.
A project in Sri Lanka sponsored by USAID AND the Overseas Education Fund (OEF) used nonformal training to prepare development workers to help women's groups orgnize income-generating projects. OEF and the Women's Bureau developed a 2-phase program for a toatl of 2 months training, which was separated by a 5-month period of field work. By the time the project came to an end in June 1982, development officers had helped rural women set up 2000 income-generating activities in Sri Lanka. their net profit was US $32,000 per month or an average of US $16 per woman. The profits from their activities surpassed the cost of the training project in less than a year. In the following year another 2000 activities were successfully started, so that beneficiaries, as of June, 1983 totalled over 22,000 people--4000 rural wmen and their families. The project, therefore, had a positive impact in a variety of areas: increased agricultural population, increased employment, increased participation of women in economic activities, development of institutional capability in rural areas, raised income of the rural poor and enhancement of health and nutrition.  相似文献   
983.
The transition to adult roles usually occurs within a normative age span. By focusing on preadolescence to late adolescence using 2-wave panel data, this research seeks to develop a more informed picture of how "early" exit from the student role and "early" entry into the adult role of parent or spouse reflect factors operating prior to adolescence. The short term consequences of adult role transition on teenage status aspirations, life plans, other psychological orientations, and parental influence are also examined. Even though multiple role transition is frequently observed, only leaving school early appears to be related to preadolescent career decisions and academic performance in high school. The determinants of early transition to the role of parent or spouse do not appear to be socioeconomic origins, parental child rearing techniques or other specific influences, academic ability or performance, or preadolescent aspirations, as has generally been hypothesized in the literature. Research dilemmas and policy implications are discussed.  相似文献   
984.

Objective

To evaluate the effect of anti-vascular endothelial growth factor (VEGF) on juxtafoveal choroidal neovascularization (CNV) secondary to multifocal choroiditis (MFC) and wet age-related macular degeneration (AMD). Methods: In this retrospective, comparative study, 20 unique eyes with CNV were divided into two groups: 10 patients affected by MFC and 10 patients diagnosed with wet AMD. They all received local intravitreal (IVT) injections of ranibizumab, with 6 months of follow-up. Retreatment injections were performed based on findings suggestive of active neovascularization.

Results

Significant improvements were observed in the juxtafoveal CNV lesions, and average central macular thickness decreased in both groups following the anti-VEGF therapy (P<0.05). The average number of injections used in MFC patients was 1.6, while three injections on average were used in wet AMD patients (Z=?2.844, P=0.009). Best-corrected visual acuity was significantly improved in MFC patients after anti-VEGF therapy (P<0.05), and there was no significant difference in wet AMD patients between before anti-VEGF therapy and 6 months later (P>0.05).

Conclusions

IVT ranibizumab resulted in good clinical outcomes for juxtafoveal CNV secondary to MFC and wet AMD, but the average number of injections used in MFC was fewer than that used in wet AMD over a 6-month observation period. Compared with the wet AMD group, visual acuity was obviously improved in the MFC group at 6 months.
  相似文献   
985.
In this paper, the effects of second-order difference-frequency wave forces on the global motion of an offshore wind turbine system with a large displacement under the survival condition are studied. In this case, the hydrodynamic force is the main force because the blades are feathered to reduce the lifting force. The first-order hydrodynamic forces are calculated by WADAM, while the second-order wave forces are calculated by a customized MATLAB module. Then the hydrodynamic coefficients are transferred to the wind turbine analytical code FAST. Through the comparisons of dynamic responses between the first- and second-order numerical models, it is found that the second-order wave forces significantly influence the motion of floating wind turbine under the survival condition. Moreover, neglecting the second-order force significantly underestimates the tension forces in the mooring lines.  相似文献   
986.
In two experiments, a recently devised mnemonic strategy was examined in the context of college students recalling the theme and contents of various paintings. With the painting-artist mnemonic strategy: (a) the artist's name is first recoded as a more concrete proxy; and (b) the recoded stimulus is then related to a prominent feature of the painting. Previous research has demonstrated that such a strategy enhances students' recall of artist names when cued with the associated paintings. The present study extends those findings by demonstrating that the strategy similarly facilitates students' recall of paintings and painting information when cued with the associated artist names. Of three different mnemonic variations included, one that incorporates a verbally described mnemonic interaction into the painting proved most effective. Suggestions for future research and educational implications are included in the discussion.  相似文献   
987.
Culture shock has been identified as a psychological reaction to a change in cultural environment. The main symptoms of culture shock are reported to be psychological disturbance, a negative reaction to the new surroundings and a longing for a more familiar environment. Research has identified culture shock as a component in the difficulties that international students face when studying in another country. One way that institutions of higher education have responded to these difficulties is to provide initial cultural orientation. In the study reported here, a group of post-graduate students who had participated in a study skills and cultural orientation course at a British university were compared with a group who had not. Contrary to the research hypothesis, the group that took part in the orientation course were significantly more homesick and reported more psychological difficulties. The overall findings cast doubt on the received view of culture shock as it affects international students. They suggest that culture shock is exacerbated by personal and social factors and this has implications for the way that international students may be helped through the experience.  相似文献   
988.
989.
990.
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