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   20126篇
  免费   1858篇
  国内免费   1319篇
  2023年   276篇
  2022年   253篇
  2021年   392篇
  2020年   703篇
  2019年   774篇
  2018年   709篇
  2017年   870篇
  2016年   889篇
  2015年   555篇
  2014年   709篇
  2013年   2311篇
  2012年   476篇
  2011年   586篇
  2010年   493篇
  2009年   727篇
  2008年   942篇
  2007年   960篇
  2006年   904篇
  2005年   778篇
  2004年   670篇
  2003年   573篇
  2002年   535篇
  2001年   348篇
  2000年   333篇
  1999年   288篇
  1998年   212篇
  1997年   184篇
  1996年   156篇
  1995年   147篇
  1994年   137篇
  1993年   107篇
  1992年   83篇
  1991年   68篇
  1990年   62篇
  1989年   42篇
  1988年   55篇
  1987年   38篇
  1985年   382篇
  1984年   432篇
  1983年   354篇
  1982年   459篇
  1981年   451篇
  1980年   455篇
  1979年   405篇
  1978年   452篇
  1977年   359篇
  1976年   359篇
  1975年   272篇
  1974年   278篇
  1973年   236篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
In contrast to the opinion of numerous authors (e.g. R. Rudner, P. Kitcher, L. R. Graham, M. Dummett, N. Chomsky, R. Lewontin, etc.) it is argued here that the formation of opinion in science should be greatly insulated from political considerations. Special attention is devoted to the view that methodological standards for evaluation of scientific theories ought to vary according to the envisaged political uses of these theories.I wish to thank the Alexander von Humboldt Foundation for having supported the work on this paper.  相似文献   
42.
This study of 20 ‘white-collar’ workers aged 20–30 measured motivation, enjoyment and access to various categories of experience in both work and leisure, and examined their relationship with psychological well-being on a number of dimensions. The method used a short questionnaire, psychological scales and the innovatory ‘experience sampling methodology’ (ESM) where respondents answer questions in a diary on the receipt of a signal from a pre-programmed watch or radio pager eight times a day for 1 week. The results show, in line with other studies, that intrinsic motivation in daily life is correlated with happiness but that, not previously reported, when motivation at work is examined both extrinsic motivation and instances where a person had to do the activity but did not wish to be doing something else, i.e. ‘positive motivational change’, are correlated with positive aspects of psychological well-being, while instances where a person wanted to do the activity but wished to be doing something else, i.e. ‘negative motivational change’, correlated with negative aspects. The results also show that enjoyment in both work and leisure correlates with aspects of psychological wellbeing; and that macro ‘flow’ experiences, where high skills and high challenges are perceived as equal, are enjoyable and interesting and come primarily from work. The study also shows that categories of experience considered important for psychological well-being and deemed to come primarily from work can be obtained in leisure. The results are discussed in the context of person—situation interactions and processes, and it is advocated that these should be studied in a variety of samples.  相似文献   
43.
There has been a great deal of discussion, in this journal and others, about obstacles hindering the evolution of the philosophy of medicine. Such discussions presuppose that there is widespread agreement about what it is that constitutes the philosophy of medicine.Despite the fact that there is, and has been for decades, a great deal of literature, teaching and professional activity carried out explicitly in the name of the philosophy of medicine, this is not enough to establish that consensus exists as to the definition of the field. And even if consensus can be obtained as to what constitutes the philosophy of medicine, this does not mean that it exists as a field.  相似文献   
44.
This two-part article examines the competition between the clonal selection theory and the instructive theory of the immune response from 1957–1967. In Part I the concept of a temporally extended theory is introduced, which requires attention to the hitherto largely ignored issue of theory individuation. Factors which influence the acceptability of such an extended theory at different temporal points are also embedded in a Bayesian framework, which is shown to provide a rational account of belief change in science. In Part II these factors, as elaborated in the Bayesian framework, are applied to the case of the success of the clonal selection theory and the failure of the instructive theory.  相似文献   
45.
Mary Anne Warren's claim that there is room for only one person with full and equal rights inside a single human skin ([1], p. 63) calls attention to the vast range of moral conflict engendered by assigning full basic moral rights to fetuses. Thereby, it serves as a goad to thinking about conflicts between pregnant women and their fetuses in a way that emphasizes relationships rather than rights. I sketch out what a care orientation might suggest about resolving gestational conflicts. I also argue that the care orientation, with its commitment to the significance of the partial and the particular, cannot be absorbed within standard, impartialist moral theory.  相似文献   
46.
Genetic counselors have participated in the Michigan Newborn Screening Program on a contractual basis since 1988. Their role includes newborn screening education and training, newborn nursery site visits, and monitoring newborn screening in hospitals. Their impact has been to improve the quality of newborn screening services by reducing errors and increasing completion of data fields on newborn screening cards, improving hospital nursery cooperation and problem solving, and enhancing health department response to specific problems.  相似文献   
47.
Retrospective and prospective reports of the onset of disruptive child behaviors were analyzed in a sample of clinic-referred boys. The younger boys (ages 7–9 years), compared with the older boys (ages 10–12 years), showed the highest level of disruptive behavior and, judging from mothers' reports, had the fastest progression of onsets from less serious to more serious problem behaviors. Despite some overlap, developmental sequences in problem behavior within the domains of hyperactivity/inattention, oppositional behavior, and conduct problems were similar across the two age groups. This was also the case for developmental sequences of overt or confrontive problem behaviors and covert or concealing conduct problems. Sequences of the onset of oppositional behavior and conduct problems were validated through prospective data, based on the information from mothers, teachers, and boys themselves. The implications of the findings are discussed for the formulation of developmental pathways of behavior and the analysis of causal factors.  相似文献   
48.
It has been estimated that at least 50% of congenital or early onset deafness loss has a genetic etiology. Genetic services have traditionally been utilized by hearing parents of deaf children. Deaf adults could also greatly benefit from genetic counseling services. However, many deaf adults do not seek genetic services due in part to the communication/language and cultural differences of this group. Deaf people communicate in various ways including the use of sign language, oral communication, writing, or a combination of these modes. Also, while some deaf individuals are part of the hearing culture, others are part of the Deaf culture which has its own language, values, and traditions. Culturally Deaf individuals do not see themselves as handicapped or disabled. The genetic professional's awareness of the communication/language and cultural needs of this group, as well as their agency's responsibilities under section 504 of the Rehabilitation Act of 1973, may increase the accessibility of genetic services and contribute to the provision of successful genetic counseling for deaf adults.Throughout this paper, the term deaf will be used to denote a person who audiologically has a hearing loss which may range from mild to profound and may be sensorineural, conductive, or mixed. However, the term Deaf is used to denote cultural deafness.  相似文献   
49.
A new method for determining the minimum number of observations per subject needed to achieve a specific generalizability coefficient is presented. This method, which consists of a branch-and-bound algorithm, allows for the employment of constraints specified by the investigator.  相似文献   
50.
This paper argues that test data are ordinal, that latent trait scores are only determined ordinally, and that test data are used largely for ordinal purposes. Therefore it is desirable to develop a test theory based only on ordinal assumptions. A set of ordinal assumptions is presented, including an ordinal version of local independence. From these assumptions it is first shown that the gamma-correlation between two tests is the product of their gamma-correlations with the true latent order. The theory is generalized to allow for heterogeneous tests by defining a weighted average local independence. The tau-correlations between total score and the latent order can be found in both homogeneous and heterogeneous cases, and a system of differential item weighting to maximize the tau-correlation between weighted items and the latent order is provided. Thus a purely ordinal test theory seems possible.Part of this work was done while the author was a Visiting Fellow at Macquarrie University. The paper has benefitted from discussions with Professors Thomas J. Reynolds and Roderick P. McDonald and from the comments of several anonymous reviewers.  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