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   330篇
  免费   35篇
  国内免费   21篇
  2023年   11篇
  2022年   8篇
  2021年   13篇
  2020年   16篇
  2019年   30篇
  2018年   22篇
  2017年   19篇
  2016年   17篇
  2015年   21篇
  2014年   19篇
  2013年   50篇
  2012年   22篇
  2011年   15篇
  2010年   18篇
  2009年   14篇
  2008年   18篇
  2007年   15篇
  2006年   9篇
  2005年   4篇
  2004年   2篇
  2003年   4篇
  2002年   1篇
  2001年   2篇
  2000年   4篇
  1999年   3篇
  1998年   1篇
  1997年   1篇
  1996年   2篇
  1995年   3篇
  1994年   4篇
  1993年   1篇
  1992年   1篇
  1989年   1篇
  1987年   1篇
  1985年   3篇
  1984年   3篇
  1983年   2篇
  1982年   1篇
  1981年   1篇
  1980年   1篇
  1979年   1篇
  1977年   1篇
  1976年   1篇
排序方式: 共有386条查询结果,搜索用时 15 毫秒
81.
In the Democratic Republic of Congo, only an estimated 2% of all AIDS patients have access to treatment. As AIDS treatment access is scaled-up in the coming years, difficult rationing decisions will have to be made concerning who will come to gain access to this scarce medical resource. This article focuses on the position, expressed by representatives of Médecins sans Frontières (MSF), that the practice of AIDS treatment access rationing is fundamentally unethical because it conflicts with the ideal of universal treatment access and the human right to health. The conclusion is that MSF's position lacks coherence, has negative practical implications, and is unfair to governments struggling to increase patient's access to AIDS treatment in unfavorable circumstances.  相似文献   
82.
The last decade has seen growing concern at the uncertain effectiveness of most fisheries assessment and management approaches as reflected by trends in global landing statistics published by FAO. These imply full exploitation of the majority of fishery resources and a serious overcapitalization of fleets at the global level. Projected increases in demand, future prices for fisheries products, and impacts of growing world populations on the ecosystem all require an urgent search for improved management frameworks.Improved management of fisheries requires, first, an understanding of the axioms and working assumptions underlying the current approaches and how these evolved in response to regional or local conditions and target species. This should promote integration of methodologies which better reflect local situations and can be expressed in the form of one or more working paradigms. These paradigms should incorporate ecosystem considerations, including environmental fluctuations and socio-economic factors. They should not assume that current production levels are independent of natural fluctuations and human impacts and should recognize the dangers of maintaining open access to marine resources throughout their seasonal cycle, life history and distribution range.Wide-use management paradigms incorporating explicit user rights, participatory management and inputs from a variety of disciplines and stakeholders are becoming popular, but must operate within a hierarchy of pre-negotiated responses to pre-specified limit reference points so that social and economic options are not lost because conservation issues have not been given precedence.Academic and research institutions could aid the management process by more participation, by promoting interdisciplinary teamwork with stakeholders and by breaking down excessive specialization and regionalization within fisheries studies. On the management side, the key elements for improving the situation seem to be consultative management frameworks that explicitly incorporate watchdog functions and implement precautionary approaches to management. Risk-averse strategies are appropriate but, given the high level of uncertainty that managers face with natural systems, fail-safe management with redundancy, both in the data sources they rely on for fishery performance and in the management measures applied, seem appropriate.For near-shore resources, governments could consider partly devolving management responsibility to appropriate levels in society, involving coastal communities, individual use rights and other vehicles for allocating access. Changing emphasis of modern technology from fisheries exploitation to improved management will be one aspect of successful future management systems, perhaps incorporating geotemporally defined access rights to near-shore and shelf resources.Recent international agreements, including the formal ratification of the Law of the Sea, show that governments are prepared for more ecologically appropriate approaches. The key stake of the fisheries industry in sustainable fisheries development needs supporting, particularly for developing countries, now the major source of aquatic marine products. High priorities for management of marine resources are rebuilding depleted resources and restoring habitats, with concern for maintaining genetic and ecological diversity. There will be a need to consider impacts of global trade on conservation of resources for future generations, if proper management is to be maintained in the face of growing demand.International agreements of relevance to future management paradigms which are compatible with the Law of the Sea Convention (and each other), include Agenda 21 of UNCED, the Biodiversity Convention, the UN Agreement on Straddling Fish Stocks and Highly Migratory Fish Stocks, the Compliance Agreement and the FAO Code of Conduct for Responsible Fisheries. Such agreements, ratified or now open for signature, provide a comprehensive basis for future customary law that can assist authorities in constructing appropriate management frameworks. Current concern remains with application of these agreements in international waters, where limited access as required for proper management still has not been established.  相似文献   
83.
Background. Helicobacter pylori (H. pylori) infection has been linked to gastritis, diarrhea, peptic ulcers, failure‐to‐thrive, anemia, as well as predisposition to gastric malignancies. Because many internationally adopted children have diarrhea, failure‐to‐thrive, and anemia on arrival to the US, we determined the prevalence of HP antibodies among these children. Methods. Serum samples from 226 unselected children from 18 countries who were evaluated in the International Adoption Clinic at New England Medical Center were tested for antibodies to H. pylori. The results of serologic screening were analyzed in relation to age at adoption, site of residence prior to adoption, weight and height, and the presence or absence of anemia, diarrhea, or intestinal parasites. Results. 31% of internationally adopted children had antibodies to H. pylori. The presence of H. pylori‐antibodies was associated with residence in an orphanage (vs. foster care) prior to adoption, older age at adoption, and coinfection with intestinal parasites. No direct effects on height or weight were identified; no associations with diarrhea or anemia were found. Conclusions. Internationally adopted children have a high incidence of exposure to H. pylori, as diagnosed serologically. Residence in an orphanage (compared with foster care), older age at adoption, and coinfection with intestinal parasites were more common among children seropositive for anti‐H. pylori antibodies.  相似文献   
84.

1. 1. For the scientific evaluation of thermal environment in relatin to human health and comfort, a number of indices have been proposed in the recent 70 years.

2. 2. However, even the newest indices are still not sufficient to explain the general thermal environment for all people including infants, the aged, the disabled etc., because such indices are based more or less on experiments using college age persons.

3. 3. Series of studies to find required thermal conditions for the disabled and the aged have been carried out from 1976 in Japan and from 1988 in Hungary.

4. 4. In 1990, the Japanese and Hungarian research groups have collaborated in an international joint experiment on the thermal environment for the disabled.

5. 5. This paper reports on the results from the first step examinations of the data from above mentioned joint experiment.

Author Keywords: Disabled; thermal environment; health; comfort; international experiment  相似文献   

85.
Ecological problems — because they involve interactions and interfaces — require for their solution a flexible, interdisciplinary approach. Ecological research can best be supported in an international, intergovernmental framework, but, at first sight, the requirements of such a framework may seem unwieldy to traditionally trained natural and social scientists. Experience acquired in implementing UNESCO's Man and the Biosphere (MAB) Programme indicates that it is possible to overcome the difficulties of conducting integrated research and to achieve internationally comparable results. The MAB Programme is a good example of both the potential and the limitations of integrated, international ecological research programs. There seem to be three imperatives for success: (1) research must be problem oriented, (2) the. unit selected for study must be sufficiently comprehensive and based on human use systems, and (3) research workers in various natural and social science disciplines and the administrative decision-makers must share responsibility for planning and execution.  相似文献   
86.
87.
This article looks at the AIDS-related controversy surrounding the experiments on and the availability of medicines in southern countries. It situates these debates in a longer-term history of transnational medicine. It highlights the rise of international therapeutic modernity at the beginning of the 1990s, based on the strict regulation of clinical trials and on the formalization of the international ethical rules governing experiments. This rise helped to change radically the reception of experiments conducted in southern countries around AIDS. With regard to this new ethics applied to clinical trials in southern countries, this article goes on to demonstrate the confrontation at the end of the 1990s between two different approaches to the universalization of healthcare. Finally, it shows how new laws on international trade have reinitiated this confrontation. Through this story, the article suggests in what sense the study of the political transformations of transnational medicine could offer a new field of investigation for the social sciences.  相似文献   
88.
新世纪的中国昆虫系统学   总被引:7,自引:1,他引:6  
黄大卫 《昆虫学报》2003,46(1):90-95
对未来我国昆虫系统学在能力建设、物种编目、理论研究、技术创新和国际合作等方面提出一系列建议。在昆虫系统学能力建设方面,政府和科学家应该在生物分类学能力评估、基础硬件建设、各级生物标本馆中建立伙伴关系(包括标本采集、标本馆管理、 科学研究、 知识共享和标本与资料交换)等方面重点开展工作。在物种编目方面,我国的昆虫物种编目有赖于各级政府和机构继续关注标本的收集和保藏,继续启动一些考察项目,以满足发现和认识昆虫物种的实际需求。在物种水平上研究以往昆虫系统学家的工作,进行地区性和世界性的昆虫类群的订正更是非常必要的。在理论研究方面,我国昆虫系统应该在下列方面积极探索:物种概念、进化理论、比较生物学理论和高级分类系统研究。在技术创新方面,我国的昆虫系统学家应该在数据库与网络技术应用、图形图像处理技术、专家鉴定系统技术、分类性状分析技术、分子生物学技术、系统发育推断程序、信息统一管理技术和知识传播技术等方面进行深入研究,以满足昆虫系统学的发展需求。在国际合作方面,要进一步推动我国昆虫系统学研究机构加入生物分类学全球战略联盟、加入各种相关国际相关组织,要促进物种信息管理系统的建立与共享,要推动研究项目国际化。  相似文献   
89.
根据居民与筹资的联系方式和卫生费用的补偿机制两个维度,按世界卫生组织和世界银行等众多机构提出的目前最富代表性的分类方法,把医药卫生体制分为市场主导型、国家福利型、公共合同型和公私功能互补型。通过对各种类型医药卫生体制的代表国家在模式与资源结构方面进行分析与比较,以起到“他山之石,可以攻玉”的效果。  相似文献   
90.
Many guidelines for international research require that studies be responsive to host community health needs or health priorities. Although responsiveness possesses great intuitive and rhetorical appeal, existing conceptions are confusing and difficult to apply. Not only are there few examples of what research the responsiveness requirement permits and what it rejects, but its application can lead to contradictory results. Because of the practical difficulties in applying responsiveness and the danger that misapplying responsiveness could harm the interests of developing countries, we argue that responsiveness should be refocused in three ways: in terms of (1) who enforces it, (2) under what standard, and (3) in what cases. We conclude that responsiveness should be applied by host country officials at the policy level with the exercise of judgment when externally funded research threatens to displace scarce local resources.  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