全文获取类型
收费全文 | 14261篇 |
免费 | 622篇 |
国内免费 | 2篇 |
出版年
2021年 | 93篇 |
2020年 | 161篇 |
2019年 | 194篇 |
2018年 | 274篇 |
2017年 | 320篇 |
2016年 | 323篇 |
2015年 | 234篇 |
2014年 | 311篇 |
2013年 | 1595篇 |
2012年 | 513篇 |
2011年 | 568篇 |
2010年 | 341篇 |
2009年 | 351篇 |
2008年 | 545篇 |
2007年 | 497篇 |
2006年 | 472篇 |
2005年 | 486篇 |
2004年 | 479篇 |
2003年 | 450篇 |
2002年 | 497篇 |
2001年 | 245篇 |
2000年 | 220篇 |
1999年 | 222篇 |
1998年 | 229篇 |
1997年 | 221篇 |
1996年 | 173篇 |
1995年 | 188篇 |
1994年 | 174篇 |
1993年 | 191篇 |
1992年 | 189篇 |
1991年 | 153篇 |
1990年 | 153篇 |
1989年 | 143篇 |
1988年 | 139篇 |
1987年 | 146篇 |
1986年 | 127篇 |
1985年 | 171篇 |
1984年 | 214篇 |
1983年 | 204篇 |
1982年 | 203篇 |
1981年 | 188篇 |
1980年 | 160篇 |
1979年 | 149篇 |
1978年 | 195篇 |
1977年 | 175篇 |
1976年 | 176篇 |
1975年 | 162篇 |
1974年 | 170篇 |
1973年 | 123篇 |
1968年 | 89篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Schneider AM Wilkins E Firestone A Everbach EC Naylor JC Simson PE 《Learning & memory (Cold Spring Harbor, N.Y.)》2003,10(5):394-400
The effect of blockade of 5-HT1A receptors was investigated on (1). retention in a mildly aversive passive-avoidance task, and (2). spontaneous single-unit activity of central nucleus of the amygdala (CeA) neurons, a brain site implicated in modulation of retention. Systemic administration of the selective 5-HT1A antagonist NAN-190 immediately after training markedly-and dose-dependently-facilitated retention in the passive-avoidance task; enhanced retention was time-dependent and was not attributable to variations in wattages of shock received by animals. Systemic administration of NAN-190 had mixed effects on spontaneous single-unit activity of CeA neurons recorded extracellularly in vivo; microiontophoretic application of 5-HT, in contrast, consistently and potently suppressed CeA activity. The present findings-that 5-HT1A receptor blockade by NAN-190 (1). enhances retention in the passive-avoidance task, and (2). does not consistently increase spontaneous neuronal activity of the CeA-provide evidence that a serotonergic system tonically inhibits modulation of retention in the passive-avoidance task through activation of the 5-HT1A receptor subtype at brain sites located outside the CeA. 相似文献
992.
Niparko JK Blankenhorn R 《Mental retardation and developmental disabilities research reviews》2003,9(4):267-275
The cochlear implant is best characterized as a device that provides access to the sound environment. The device enables the hearing pathway to respond to environmental and speech sounds, providing informational cues from the surroundings and from others that may escape visual detection. As the developmental effects of a profound hearing loss are multiple, cochlear implants have been applied to ever younger children in an attempt to promote a more normal level of developmental learning through audition. In deafness, transducer elements of the inner ear fail to trigger auditory nerve afferent nerves in the presence of sound input. However, large reserves of afferent fibers exist even in the auditory nerve of a profoundly deaf patient. Furthermore, these nerve fibers retain the ability to respond to prosthetic activation. Through developmental learning in the early, formative years, auditory centers of the brain appear capable of processing information from the implant to provide speech comprehension and oral language development. Multichannel implants have replaced original single channel designs. multichannel devices enable larger percentages of recipients to recognize the spoken word without visual cues because they provide spectral information in addition to temporal and intensity cues. Testing under conditions of auditory (implant)-only input reveals significant open-set speech understanding capabilities in more than 75% of children after three years of device use. The benefit provided by implants may vary with a number of conditions including: hearing history, age of deafness onset, age at implantation, etiology of deafness, linguistic abilities, and the presence of a motivated system of support of oral language development. Patient variables should be given individual consideration in judging candidacy for a cochlear implant and in planning rehabilitative and education services after surgery and activation of the device. 相似文献
993.
Halvorsen JG 《CNS spectrums》2003,8(3):217-224
Whose job is it to discover and manage patients' sexual concerns? If you believe that you have a role to play, just what is that role and how will you perform it? Sexual disorders are common, yet infrequently diagnosed. A willingness to inquire about sexual function is the most critical diagnostic step for clinicians. Once a problem is discovered, a systematic diagnostic process can uncover etiologic organic and psychogenic factors using customary diagnostic tools, including taking a psychosexual and medical history, comprehensive and focused physical examinations, psychological assessment instruments, laboratory tests, and special procedures. 相似文献
994.
Jackson JP 《History of psychology》2003,6(2):195-202
In a recent article, Howard H. Kendler (2002) criticized Kenneth B. Clark and the other social scientists who worked in Brown v. Board of Education for polluting their science with value judgments. This article argues that Kendler's critique is misguided because it conflates a policy judgment with a value judgment. In addition, Kendler inconsistently applied his own standard of objectivity when he examined in the social science used in Brown. 相似文献
995.
Gardenier JS 《Science and engineering ethics》2003,9(3):425-434
This paper informally summarizes a two-day symposium held at the U.S. National Academy of Sciences in Washington, D.C., September
5–6, 2002. The issue was to what extent the progress of science and societal capacity for continued technological innovation
are threatened by excessive protection of intellectual property. Excessive protection creates disadvantages not only for scientists
and inventors but also for educators/students and for librarians/clientele. Speakers from a variety of disciplines and institutions
agreed unanimously that scientific and technological progress is, indeed, under serious threat. Various opinions were expressed
about the degree of threat, currently and prospectively, as well as what counter-measures are best suited to resist undue
restrictions on creative uses of scientific and technical data and information. This summary is based entirely on the author’s
notes from the symposium, and the commentary offered is his alone. My apologies to the speakers if this paper does not accurately
reflect the primary intent of their presentations. The “Suggested Readings” offered at the end are not specific to the speakers’
statements but rather are offered as a general resource to aid further research. The definitive record of the symposium is
planned to be available from the National Academies Press as a Proceedings publication in the summer of 2003.
John Gardenier is an independent researcher, ethicist and science writer. 相似文献
996.
Sherrington J 《Science and engineering ethics》2003,9(3):419-423
This paper was presented at a seminar that outlined the work of the Surrey Ethics Forum. The Forum provides an opportunity for reflection by staff of the Federal University of Surrey and its Associated Institutions on ethical questions, the place of ethics in the curriculum and the role of ethics in the life of future graduates. The purpose of this paper is to argue that openness to the relationship between ethics and faith is itself an ethical task because both ethics and faith claim to protect human dignity and give meaning to the concept of "human flourishing". Analysis of the relationship between ethics, faith, flourishing and narrative can lead to clearer understanding of differences in ethical debates. 相似文献
997.
998.
999.
Two experiments investigated the mechanisms underlying analogical transfer in the clue-word reading task developed by Goswami and her colleagues. Across both experiments, an equivalent number of "analogy" responses were made regardless of whether the clue word was seen or just heard. In addition, the number of "analogy" responses to words sharing both orthographic and phonological overlap with the clue words was no greater than that shown to words sharing only pronunciations. These results provide no evidence for the view that beginning readers make genuine orthographic-based analogies. Instead, the findings are interpreted within a framework in which phonological priming, in combination with the children's own partial decoding attempts based on limited orthographic knowledge, account for their performance on the clue-word task. It is concluded that the extent to which beginning readers make orthographic analogies is overestimated and as a consequence, theories that emphasize the importance of orthographic analogy as a mechanism driving the development of early reading skills need to be questioned. 相似文献
1000.
Ziman J 《Science and engineering ethics》2001,7(2):165-176
Research scientists are trained to produce specialised bricks of knowledge, but not to look at the whole building. Increasing public concern about the social role of science is forcing science students to think about what they are actually learning to do. What sort of knowledge will they be producing, and how will it be used? Science education now requires serious consideration of these philosophical and ethical questions. But the many different forms of knowledge produced by modern science cannot be covered by any single philosophical principle. Sociology and cognitive psychology are also needed to understand what the sciences have in common and the significance of what they generate. Again, traditional modes of ethical analysis cannot deal adequately with the values, norms and interests activated by present-day technoscience without reference to its sociological, political and economic dimensions. What science education now requires is ‘metascience’, a discipline that extends beyond conventional philosophy and ethics to include the social and humanistic aspects of the scientific enterprise. For example, students need to learn about the practices, institutions, career choices, and societal responsibilities of research scientists, and to rehearse in advance some of the moral dilemmas that they are likely to meet. They need also to realise that science is changing rapidly, not only in its research techniques and organisational structures but also in its relationships with society at large. 相似文献