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   1029篇
  免费   15篇
  国内免费   18篇
安全科学   79篇
废物处理   38篇
环保管理   196篇
综合类   196篇
基础理论   211篇
污染及防治   223篇
评价与监测   75篇
社会与环境   39篇
灾害及防治   5篇
  2023年   12篇
  2022年   11篇
  2021年   21篇
  2020年   23篇
  2019年   13篇
  2018年   31篇
  2017年   20篇
  2016年   45篇
  2015年   30篇
  2014年   41篇
  2013年   78篇
  2012年   38篇
  2011年   77篇
  2010年   48篇
  2009年   52篇
  2008年   57篇
  2007年   45篇
  2006年   49篇
  2005年   42篇
  2004年   35篇
  2003年   37篇
  2002年   34篇
  2001年   15篇
  2000年   23篇
  1999年   9篇
  1998年   11篇
  1997年   8篇
  1996年   11篇
  1995年   13篇
  1994年   14篇
  1993年   9篇
  1992年   13篇
  1991年   10篇
  1990年   7篇
  1989年   3篇
  1988年   9篇
  1987年   5篇
  1986年   7篇
  1985年   7篇
  1984年   2篇
  1983年   8篇
  1982年   7篇
  1981年   10篇
  1980年   7篇
  1979年   2篇
  1977年   4篇
  1970年   1篇
  1964年   1篇
  1962年   1篇
  1956年   1篇
排序方式: 共有1062条查询结果,搜索用时 15 毫秒
141.
Mosaicism for the Wolf-Hirschhorn syndrome, del(4)(p16), is extremely rare and has not been reported in association with a numerical chromosome abnormality. We report the prenatal diagnosis of mosaic del(4)(p16) and non-mosaic trisomy 21 in a 16-week female fetus. The pregnancy ended in spontaneous abortion at 34 weeks secondary to fetal demise. The fetus had features of both 4p – and trisomy 21.  相似文献   
142.
143.

Problem

Exercise-based research interventions demonstrate reduced risk and rates of falls for community dwelling older adults; however, little is known about effective mechanisms for the translation, implementation, and maintenance of these interventions in community settings.

Method

The RE-AIM framework was used to assess the translatability of an effective exercise-based research intervention in a community setting. Questions included: Reach — Would the target population attend? Effectiveness — What was the adherence and compliance to the program? Were there individual improvements in falls risk factors? Adoption: Would staff at the center adopt the program and offer it past the funding period? Implementation — What adaptations, including optimal frequency and duration, should be made to meet the community needs, still adhere to core elements and achieve similar outcomes? Maintenance — Would the program be sustained by our community partners?

Discussion

The process of translating a controlled research intervention targeting older adults at risk of falls into a community setting was challenging. Licensed professionals developed the infrastructure to safely and effectively deliver the program. The end product was highly appealing program to our target audience, resulted in improved outcomes and was successfully adopted and maintained by the community partner.

Summary

Partnerships between community and healthcare providers are key to successful implementation of falls prevention interventions. Lessons learned from this experience can be applied to the translation of future exercise-based falls prevention interventions.  相似文献   
144.
145.
146.
No clear answer concerning whether multivitamin/folate supplementation prevents neural tube defects (NTDs) is provided by three studies in the United States. All these studies are occurrence in nature, no recurrence studies having been conducted. The Atlanta Birth Defects Study is subject to pronounced memory and recall biases, the length between event and interview being as long as 16 years. In a second study (Boston University), objections can be raised to certain aspects of the experimental design, and the claim that 22 per cent of women started vitamins sufficiently early after pregnancy diagnosis to influence NTD formation is suspicious. Our NICHD case control study of 541 women in California and Illinois revealed no evidence for multivitamins or folic acid preventing NTDs. U.S. public policy-makers face difficulties in applying results of recurrence or occurrence studies in high-risk areas to low-risk areas in the U.S.  相似文献   
147.
148.
An amniocentesis was performed at 13.3 weeks' gestation for advanced maternal age. A mosaic sex chromosome pattern was found: of 50 cells examined, 34 had a 45,X karyotype. In 14 cells with a modal number of 46, a recognizable Y was substituted by a small non-fluorescent marker. C-banding identified the marker as an isodicentric in 12 cells. In two cells, the non-fluorescent marker appeared to be monocentric and looked like a non-fluorescent del (Yq), but could have been an isodicentric Y with inactivation of one of the centromeres. Two cells with a modal number of 47 showed two copies of the monocentric marker. Fluorescent in situ hybridization with an alpha satellite Y-specific centromeric probe confirmed the Y-chromosome origin of the markers and allowed for more accurate prenatal diagnostic information.  相似文献   
149.
Maternal serum CA 125 levels were determined at 9–11 menstrual weeks for 26 cases of trisomy 13 (n = 4), trisomy 18 (n = 7), trisomy 21 (n = 15), and appropriate controls. There were no statistically significant differences between groups.  相似文献   
150.
Urban stream restoration continues to be used as an ecological management tool, despite uncertainty about the long‐term sustainability and resilience of restored systems. Evaluations of restoration success often focus on specific instream indicators, with limited attention to the wider basin or parallel hydrologic and geomorphic process. A comprehensive understanding of urban stream restoration progress is particularly important for comparisons with nonurban sites as urban streams can provide substantial secondary benefits to urban residents. Here, we utilize a wide range of indicators to retrospectively examine the restoration of Nine Mile Run, a multi‐million dollar stream restoration project in eastern Pittsburgh (Pennsylvania, USA). Examination of available continuous hydrological data illustrates the high cost of failures to incorporate the data into planning and adaptive management. For example, persistent extreme flows drive geomorphic degradation threatening to reverse hydrologic connections created by the restoration and impact the improved instream biotic communities. In addition, human activities associated with restoration efforts suggest a positive feedback as the stream restoration has focused effort on the basin beyond the reach. Ultimately, urban stream restoration remains a potentially useful management tool, but continued improvements in post‐project assessment should include examination of a wider range of indicators.  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