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   990篇
  免费   80篇
  国内免费   67篇
  2024年   4篇
  2023年   20篇
  2022年   20篇
  2021年   30篇
  2020年   45篇
  2019年   54篇
  2018年   56篇
  2017年   45篇
  2016年   48篇
  2015年   35篇
  2014年   40篇
  2013年   140篇
  2012年   31篇
  2011年   51篇
  2010年   46篇
  2009年   40篇
  2008年   67篇
  2007年   49篇
  2006年   55篇
  2005年   40篇
  2004年   28篇
  2003年   18篇
  2002年   18篇
  2001年   14篇
  2000年   16篇
  1999年   11篇
  1998年   11篇
  1997年   8篇
  1996年   9篇
  1995年   10篇
  1994年   7篇
  1993年   4篇
  1992年   5篇
  1991年   4篇
  1990年   5篇
  1989年   3篇
  1988年   2篇
  1987年   3篇
  1986年   1篇
  1985年   2篇
  1984年   3篇
  1983年   5篇
  1982年   5篇
  1981年   3篇
  1980年   2篇
  1979年   4篇
  1978年   3篇
  1977年   7篇
  1976年   6篇
  1975年   4篇
排序方式: 共有1137条查询结果,搜索用时 15 毫秒
991.
Livestock production has been confronted with several epidemics over the last decades. The morality of common animal disease strategies—stamping out and vaccination—is being debated and provokes controversies among farmers, authorities and the broader public. Given the complexity and controversy of choosing an appropriate control strategy, this article explores the potential of nano-enabled diagnostics in future livestock production. At first glance, these applications offer promising opportunities for better animal disease surveillance. By significantly shortening the reaction time from diagnosis to appropriate control, they could complement the current disease management strategies. Although nano-enabled diagnostics will not make livestock disease eradication strategies redundant or completely free of the culling of infected animals, these diagnostics could significantly reduce the number of culled animals and animal suffering. This article aims to demonstrate that the ethical assessment of advanced diagnostics can build on the experiences with decision making in biomedical ethics where nonmaleficence, beneficence, autonomy and justice serve as important benchmarks. Nano-enabled diagnostics may be an ethically sound solution if it can resolve the dilemma between stamping out and vaccination in favor of the latter and if it can balance the autonomy–paternalism dilemma between farmers and authorities. The technology should allow to be switched on and off by farmers, whilst simultaneously allowing for a weak paternalism on behalf of authorities in order to benefit the farmer and broader society and to protect them from harm.
Johan EversEmail:
  相似文献   
992.
Alexander George made a seminal contribution to theories of preventive diplomacy, crisis management, deterrence, and coercive diplomacy. Although he made his contribution in the highly structured environment of the Cold War, his analysis of the close connections between positive and negative inducements, the importance of interests in shaping outcomes, and the dangers of threat-based strategies as substitutes for policy speaks to the central challenges of contemporary global politics.  相似文献   
993.
This study assessed the potential influence of social desirability (SD) response bias on the E, N, and P EPQ-R scores at the level of individual items. The study was based on a bidimensional IRT model which was fitted in a large sample. This allowed a detailed analysis of both the internal validities of the items and the content of the items which were most affected by SD. The E items were least affected by SD, but the direction of the impact depended on the type of item. As expected, in the N and P cases the relations obtained were consistently negative, but the strength of the SD impact also depended considerably on the type of item. The P scale was the most problematic in terms of convergent and discriminant validity.  相似文献   
994.
This study evaluated the efficacy of a contingency management (CM) intervention to promote smoking cessation in methadone‐maintained patients. Twenty participants, randomized into contingent (n = 10) or noncontingent (n = 10) experimental conditions, completed the 14‐day study. Abstinence was determined using breath carbon monoxide and urine cotinine levels. Contingent participants received voucher‐based incentives for biochemical evidence of smoking abstinence. Noncontingent participants earned vouchers independent of smoking status. Contingent participants achieved significantly more smoking abstinence and longer durations of continuous smoking abstinence than did noncontingent participants. These results support the potential efficacy of using voucher‐based CM to promote smoking cessation among methadone‐maintained patients.  相似文献   
995.
Fifty-eight smokers received abstinence-contingent monetary payments for 1 (n  =  15) or 14 (n  =  43) days. Those who received contingent payments for 14 days also received 0, 1, or 8 experimenter-delivered cigarette puffs on 5 evenings. The relative reinforcing effects of smoking were assessed in a 3-hr session on the final study day, when participants made 20 choices between smoking or money. The reinforcement contingencies exerted robust control over smoking, and programmed smoking lapses produced few discernible effects. These results further illustrate the robust control that reinforcement contingencies can exert over cigarette smoking and suggest that any effects of lapses on the relative reinforcing effects of smoking are modest under conditions involving abstinence-contingent reinforcement contingencies.  相似文献   
996.
Contingency management (CM) is effective in enhancing retention in therapy. After an 8-week baseline, four community-based substance abuse treatment clinics were exposed in random order to 16 weeks of standard care with CM followed by 16 weeks of standard care without CM or vice versa. In total, 75 outpatients participated. Patients who were enrolled in the clinics when the CM treatment phase was in effect attended a significantly greater percentage of therapy sessions than patients who were enrolled in treatment when CM was not in effect. This study is one of the first to investigate CM in community settings implemented entirely by community clinicians, and results suggest that CM is effective in improving therapy attendance.  相似文献   
997.
We investigated the extent to which a contingency management (CM) procedure that deducted money from a grand total available at the end of the study compared to a procedure in which money accumulated with continued abstinence from cigarette smoking. Results suggested that the procedure in which money increased contingent on abstinence resulted in a significantly greater likelihood of obtaining a clinically relevant (i.e., 48-hr) period of abstinence. In terms of attendance, participants in the condition in which monetary reinforcement accrued with consecutive instances of abstinence were significantly less likely to miss consecutive appointments than those in which money was deducted for failure to abstain.  相似文献   
998.
Despite the progress women have made since the inception of Title IX, many still face discrimination in the sport workplace. Given the assumption that time-use is gendered, the traditional culture of US intercollegiate sport stands in sharp contrast to the evolving notion of work-life balance. This study employed a qualitative life course perspective to examine the experiences of seventeen head coach mothers in NCAA institutions. Results focus on the participants’ historical/social context, biography, relationships, interplay between these factors, and most importantly the role of administrators as life linkages. The results suggest that it is insufficient for managers to view the employee in isolation or to neglect the organizational culture in athletics. Supervisor attention to this, while time and effort-intensive, can impact employee well-being.  相似文献   
999.
Rotation forest (RoF) is an ensemble classifier combining linear analysis theories and decision tree algorithms. In recent existing works, RoF was widely applied to various fields with outstanding performance compared to traditional machine learning techniques, given that a reasonable number of base classifiers is provided. However, the conventional RoF algorithm suffers from classifying linearly inseparable datasets. In this study, a hybrid algorithm integrating kernel principal component analysis (KPCA) and the conventional RoF algorithm is proposed to overcome the classification difficulty for linearly inseparable datasets. The radial basis function (RBF) is selected as the kernel for the KPCA method to establish the nonlinear mapping for linearly inseparable data. Moreover, we evaluate various kernel parameters for better performance. Experimental results show that our algorithm improves the performance of RoF with linearly inseparable datasets, and therefore provides higher classification accuracy rates compared with other ensemble machine learning methods.  相似文献   
1000.
采用问卷法对377名高校学生进行调查,以考察自我感知的外表吸引力、外倾性、表现欲及自拍发布行为四者之间的关系。结果显示:(1) 自我感知的外表吸引力显著地正向预测个体的自拍发布行为;(2)外倾性在自我感知的外表吸引力与自拍发布行为之间起部分中介作用;(3) 表现欲能调节外倾性与自拍发布行为的关系,随着表现欲的增加,外倾性的中介作用增大。本研究进一步揭示了个体自拍发布行为的作用机制,促进了人们对网络自我表露行为的认识。  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