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   31637篇
  免费   1193篇
  国内免费   18篇
  32848篇
  2019年   410篇
  2018年   560篇
  2017年   608篇
  2016年   572篇
  2015年   428篇
  2014年   478篇
  2013年   2431篇
  2012年   853篇
  2011年   962篇
  2010年   631篇
  2009年   625篇
  2008年   872篇
  2007年   812篇
  2006年   760篇
  2005年   641篇
  2004年   591篇
  2003年   636篇
  2002年   581篇
  2001年   1195篇
  2000年   1169篇
  1999年   841篇
  1998年   367篇
  1997年   298篇
  1995年   296篇
  1994年   302篇
  1992年   718篇
  1991年   693篇
  1990年   657篇
  1989年   609篇
  1988年   581篇
  1987年   578篇
  1986年   544篇
  1985年   606篇
  1984年   472篇
  1983年   368篇
  1981年   294篇
  1979年   462篇
  1978年   343篇
  1977年   327篇
  1976年   305篇
  1975年   412篇
  1974年   416篇
  1973年   476篇
  1972年   384篇
  1971年   319篇
  1970年   306篇
  1969年   327篇
  1968年   377篇
  1967年   333篇
  1966年   385篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
271.
One interpretation of the doctrine of double effect (DDE) holds that in situations in which good can be secured for some only if others suffer harm, the pursuit of a good tends to be less acceptable when a resulting harm is intended as a means rather than when it is merely foreseen. The doctrine captures certain moral intuitions about pairs of cases which have the same consequential profiles but in which the character of the intention differs. Quinn examines the DDE using three pairs of contrasting cases, two of which are medical examples: the "Direction of Resources" case and the "Guinea Pig" case, both involving allocation of life-saving resources, and the "Craniotomy" case and the "Hysterectomy" case, both involving fetal vs. maternal life. He concludes that the DDE "embodies our sense that certain forms of forced strategic subordination are especially inappropriate among free and equal agents."  相似文献   
272.
The present 2 x 2 study deals with the influence of controllability and predictability of an aversive noise stimulus on a subsequent learning task. Eighty-four subjects participated in two experiments. In correspondence with the concept of learned helplessness, controllability was shown to be the dominant factor in the first experiment. In the second experiment, a modified test task was used in which both factors were shown to act in specific ways: The main influence of controllability is upon response measures (latency, omission), whereas unpredictability retardates learning of new predictive connections. The results are discussed in terms of contingency learning.  相似文献   
273.
Conclusion The community psychologist should be attuned to the phenomenon that deprived communities are not always attracted by goals that are understandable to the middle-class power structure. Persons in a constant battle against poverty settle at first for immediate visible gains. An increase in the number of children getting lunch at school is tangible; a revision of the curriculum to produce better competence in mathematics is not quite so tangible.I thank Prof. L. M. Noth, Professor and Head, Community Medicine, AIIMS, New Delhi, and Officer In Charge, Comprehensive Rural Health Service Project, Ballabgarh, for encouraging me to initiate and demonstrate community activities at Panehrakhurd, when I was associated with AIIMS. Thanks also to Mr. Parma Nand and Mr. Gurmeet Lal, President and General Secretary, respectively, of Dr. Ambdkar Mission Society Sofipind for their kind cooperation in trying out the developmental work.  相似文献   
274.
Subjects saw kinetic depth displays whose shape (sphere or cylinder) was defined by luminous dots distributed randomly on the surface or in the volume of the object. Subjects rated perceived 3-D depth, rigidity, and coherence. Despite individual differences, all 3 ratings increased with the number of dots. Dots in the volume yielded ratings equal to or greater than surface dots. Each rating varied with 3 of 4 factors (shape, distribution, numerosity, and perspective), but the ratings either between trials or between conditions were often uncorrelated. Object shape affected rigidity but not depth ratings. Veridically perceived polar displays had slightly lower rigidity but higher depth ratings than parallel projection displays. (Reversed polar displays were always grossly nonrigid.) The interaction of ratings and stimulus parameters requires theories and experiments in which different KDE ratings are not treated interchangeably.  相似文献   
275.
The influence of prior linguistic predictive and nonpredictive context on the comprehension of reversible passive sentences was investigated in 16 adults with aphasia. Eight subjects were classified as fluent and 8 as nonfluent. Subjects were presented with the sentences in isolation and preceded by nonpredictive and predictive contextual paragraphs. The overall results indicated that the subjects benefited significantly from the prior contextual narratives regardless of whether the paragraphs were predictive or nonpredictive. There were no significant differences between the two subject groups. The significant facilitation generated by the nonpredictive context suggests that redundancy of information may play a role in comprehension.  相似文献   
276.
A total of 178 reading disabled children were randomly assigned to one of three treatment conditions providing training in word recognition and decoding skills (DS), oral and written language (OWLS), or classroom survival skills (CSS. an alternative treatment control). Pre- and post-treatment comparisons on an array of standardized and experimental measures indicated that the two experimental treatments (DS, OWLS) resulted in improvement on selected tests significantly greater than that resulting from a third treatment intervention which controlled for treatment time and individual attention (CSS). Effects specific to each experimental treatment were identified, as well as some generalized treatment advantages shared by both experimental groups at post-test. These results indicate that some of the deficits associated with developmental dyslexia are amenable to treatment. Greater generalization of treatment effects was observed following the DS than the OWLS treatment. While DS-instructed children exhibited better word recognition skills, however, their knowledge of grapheme-phoneme correspondence rules was not improved. Several OWLS-specific effects observed on experimental reading and language measures were not replicated on standardized tests which purport to measure the same skills. These results are discussed with respect to (i) possible mechanisms by which disabled readers may acquire word recognition skills, (ii) their failure to acquire and use grapheme-phoneme correspondence rules, and (iii) a possible reduced tendency in the present population to generalize newly acquired specific knowledge to related knowledge domains.  相似文献   
277.
Two alternative hypotheses were considered concerning the process of prolonged search for an uncommon word in response to hearing its definition. One alternative is that a conscious retrieval effort brings the target progressively closer to threshold. The second is that the retrieval process is a random neural exploration outside of conscious control. A tachistoscopic probe was devised to compare word recognition thresholds after 10 sec versus 30 sec of presumed search time. Results failed to show a difference between the two delay conditions and were interpreted as inconsistent with the first alternative but consistent with the second.  相似文献   
278.
Psychological stress has been shown to affect immune system status and function, but most studies of this relationship have focused on acute stress and/or laboratory situations. The present study compared total numbers of leukocytes and lymphocyte subpopulations (determined by flow cytometry) and antibody titers to latent and nonlatent viruses among a group of chronically stressed individuals living near the damaged Three Mile Island (TMI) nuclear power plant with those of a demographically comparable control group. Urinary catecholamine and cortisol levels were also examined. Residents of the TMI area exhibited greater numbers of neutrophils, which were positively correlated with epinephrine levels. The TMI group also exhibited fewer B lymphocytes, T-suppressor/cytotoxic lymphocytes, and natural killer cells. Antibody titers to herpes simplex were significantly different across groups as well, whereas titers to nonlatent rubella virus as well as IgG and IgM levels were comparable.  相似文献   
279.
This work has received financial support from FONDECYT (Project 1111-88). The authors also acknowledge the helpful comments of Dr. Bruce Cassels.  相似文献   
280.
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