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   185篇
  免费   0篇
  国内免费   5篇
  2022年   2篇
  2020年   1篇
  2019年   2篇
  2018年   7篇
  2016年   5篇
  2015年   1篇
  2014年   18篇
  2013年   16篇
  2012年   1篇
  2011年   11篇
  2010年   6篇
  2009年   16篇
  2008年   16篇
  2007年   15篇
  2006年   19篇
  2005年   14篇
  2004年   14篇
  2003年   6篇
  2002年   11篇
  2001年   2篇
  1999年   2篇
  1996年   2篇
  1995年   1篇
  1992年   1篇
  1988年   1篇
排序方式: 共有190条查询结果,搜索用时 0 毫秒
41.
比较传统与改良鼻内镜下鼻骨复位术两种手术方式,探讨改良鼻内镜下鼻骨复位术的可行性与优势所在。局部麻醉下分别采用传统与改良鼻内镜下鼻骨复位术对闭合性单纯鼻骨骨折及部分合并鼻中隔骨折的患者进行复位后,比较两种手术方式患者的复位效果、术中出血、术后不适及住院时间。改良鼻内镜下鼻骨复位术较传统鼻内镜下鼻骨复位具有麻醉效果好、鼻...  相似文献   
42.
通过研究慢性HBV感染者前C区变异及T细胞免疫功能与疾病的相关性,评估前C(preC)区变异及T细胞免疫功能对于慢性乙型肝炎(chronichepatitisB,CHB)预后的影响。分别采用实时荧光法、突变特异PCRmsPCR法及微粒酶免疫分析法对150例HBV-DNA阳性的CHB及50例健康体检者进行血清HBV-DN...  相似文献   
43.
克服肿瘤干细胞耐药性的策略和思路   总被引:1,自引:1,他引:0  
肿瘤干细胞(cancersterncells,CSCs)是肿瘤细胞的祖细胞。已有的研究表明,肿瘤干细胞对多种化疗药物具有耐药性,是导致肿瘤治疗后复发的根源。研究针对肿瘤干细胞的治疗方法,克服肿瘤干细胞耐药性,将给肿瘤治疗模式带来全新的改变,有望彻底改善肿瘤患者的预后。  相似文献   
44.
Theories of learning have historically taken, as their starting point, the assumption that learning processes have universal applicability. This position has been argued on grounds of parsimony, but has received two significant challenges: first, from the observation that some kinds of learning, such as spatial learning, seem to obey different rules from others, and second, that some kinds of learning take place in processing modules that are separate from each other. These challenges arose in the behavioural literature but have since received considerable support from neurobiological studies, particularly single neuron studies of spatial learning, confirming that there are indeed separable (albeit highly intercommunicating) processing modules in the brain, which may not always interact (within or between themselves) according to classic associative principles. On the basis of these neurobiological data, reviewed here, it is argued that rather than assuming universality of associative rules, it is more parsimonious to assume sets of locally operating rules, each specialized for a particular domain. By this view, although almost all learning is associative in one way or another, the behavioural-level characterization of the rules governing learning may vary depending on which neural modules are involved in a given behaviour. Neurobiological studies, in tandem with behavioural studies, can help reveal the nature of these modules and the local rules by which they interact.  相似文献   
45.
The President’s Council on Bioethics has addressed the moral status of human preembryos in its reports on stem cell research and human therapeutic cloning. Although the Council has been criticized for being hand-picked to favor the right-to-life viewpoint concerning human preembryos, it has embraced the idea that the right-to-life position should be defended in secular terms. This is an important feature of the Council’s work, and it demonstrates a recognition of the need for genuine engagement between opposing sides in the debate over stem cell research. To promote this engagement, the Council has stated in secular terms several arguments for the personhood of human preembryos. This essay presents and critiques those arguments, and it concludes that they are unsuccessful. If the best arguments in support of the personhood of human preembryos have been presented by the Council, then there are no reasonable secular arguments in support of that view.  相似文献   
46.
The author, a member of the U.S.President's Council on Bioethics, discussesethical issues raised by human cloning, whetherfor purposes of bringing babies to birth or forresearch purposes. He first argues that everycloned human embryo is a new, distinct, andenduring organism, belonging to the speciesHomo sapiens, and directing its owndevelopment toward maturity. He then distinguishesbetween two types of capacities belonging toindividual organisms belonging to this species,an immediately exerciseable capacity and abasic natural capacity that develops over time. He argues that it is the second type ofcapacity that is the ground for full moralrespect, and that this capacity (and itsconcomitant degree of respect) belongs tocloned human embryos no less than to adulthuman beings. He then considers and rejectscounter-arguments to his position, includingthe suggestion that the capacity of embryos isequivalent to the capacity of somatic cells,that full human rights are afforded only tohuman organisms with functioning brains, thatthe possibility of twinning diminishes themoral status of embryos, that the fact thatpeople do not typically mourn the loss of earlyembryos implies that they have a diminishedmoral status, that the fact that earlyspontaneous abortions occur frequentlydiminishes the moral status of embryos, andthat his arguments depend upon a concept ofensoulment. He concludes that if the moralstatus of cloned human embryos is equivalent tothat of adults, then public policy should bebased upon this assumption.  相似文献   
47.
This paper examines Romanian bioethics regulations for biomedical sciences, looking in particular at the genetics area as a source for conflict of interest. The analysis is focused on the organizational level, national regulations, the sources for generating conflicts of interest, and management of conflicts. Modern biotechnology and gene technology are among the key technologies of the twenty-first century. The application of gene technology for medical and pharmaceutical purposes is widely accepted by society, but the same cannot be said of the development and application of gene technology in agriculture and food processing. Because the use of a technology in the production and processing of food is regarded more sceptically than in the production of biomedical products, there can be areas of conflict in many cases when communication is undertaken about gene technology in the agro-food sector. Ethical concerns play an important factor in this, but a society’s attitude to a developing technology is an amalgam of many effects which are beyond ethics as such. This paper contains a study carried out by the author for the Romanian Association for Consumer Protection about the attitudes of consumers towards genetically modified (GM) foods. This study revealed that in Romania more than 98% of consumers did not know anything about GM foods and frequently were confused about the definitions of these terms. In conclusion, it is necessary to say that there is a low level of knowledge regarding biotechnology in Romania and this is an important reason why there is neither public acceptance of gene technology products nor is there a rejection. An earlier version of this paper was presented at an International Conference on “Conflict of Interest and its Significance in Science and Medicine” held in Warsaw, Poland on 5–6 April, 2002. Ioana Ispas, MD in Molecular Biology, is a scientific researcher and Member of the Romanian Association for Consumer Protection, NCP for FP5-Quality of life and management of living resources.  相似文献   
48.
王玮文  邵枫  刘美  孙萌  林文娟 《心理学报》2007,39(6):1034-1040
目的:研究慢性不确定应激对大鼠急性整体热水浴后外周血和脾脏免疫细胞热休克蛋白70(Heat shock protein 70, HSP70)表达的影响。方法:随机将大鼠分成慢性应激组和控制组(每组14只)。通过4周的慢性不确定性应激诱发实验组大鼠明显的抑郁行为,此期间控制组大鼠正常饲养。随后给予大鼠42度整体热水浴刺激,维持直肠温度41度25min。热刺激后6h,采用流式细胞仪测定大鼠外周血和脾脏免疫细胞HSP70 水平。结果:与控制组大鼠相比,慢性应激大鼠在急性热刺激后HSP70合成明显减少。控制组大鼠的所有被检测的免疫细胞热应激后HSP70合成均明显增加。相反,慢性应激大鼠仅在外周血的单核细胞和粒细胞检测到HSP70合成增加,同时升高的水平明显低于控制组大鼠。结论:慢性应激降低大鼠免疫细胞HSP70的热诱导反应,提示HSP70保护性作用减弱可能参与了慢性应激损害免疫细胞功能的生物学过程  相似文献   
49.
To many commentators outside South Korea, the Hwang Woo Suk scandal involving human embryonic stem cell (hESC) research was just another spectacular case of misconduct in the life sciences. As such, it is generally assumed to have revealed the drawbacks of research in scientifically and ethically less-developed societies. Such thinking ignores the history, sophistication, and distinctive features of the public debate over hESC research in South Korea. Disputes over the social and ethical implications of hESC research had taken place for some time before the scandal erupted. Moreover, unlike in some other countries, where resistance to hESC research was prompted by religious conservatives, the most serious critique of the country's rapid move into the field came from progressive social movement activists—including feminists and environmentalists. These activists were, in fact, part of the non-governmental organization coalition to impose stricter social controls on biotechnology. This campaign was motivated by broader political and social concerns beyond specific biosafety or bioethical issues. The activists involved in the coalition feared that the capitalist–developmentalist drive toward biotechnology would threaten the public interest and democracy, and ultimately block South Korea's road to becoming a democratic nation founded on the values of social justice, equality, participation, and sustainability. In contesting South Korea's prevailing approaches to hESC research, they challenged, albeit unsuccessfully, the dominant ‘national sociotechnical imaginary’ that articulates the role of science and technology in relation to the future survival and well-being of the nation primarily in terms of its industrial competitiveness.  相似文献   
50.
干细胞纠缠     
干细胞生物学的研究目前还处于一个“灰箱”的状态,阻止机制阐明的最大障碍之一可能是因为缺少一个行之有效且又不会改变干细胞自然属性的研究平台。这个平台的中心是要有一个像“薛定谔的猫”那样能即时报告干细胞属性的作用角色。目前,主要有两方面阻碍了干细胞研究的进一步深化,一个是干细胞如何不对称分裂,另一个是干细胞巢的结构组成。其实,在微观世界的许多研究中,如物理学中的量子论,都是因为缺少那只“薛定谔的猫”才使研究的钟摆停在原地不动。  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