全文获取类型
收费全文 | 6191篇 |
免费 | 1758篇 |
国内免费 | 818篇 |
专业分类
8767篇 |
出版年
2024年 | 12篇 |
2023年 | 59篇 |
2022年 | 102篇 |
2021年 | 183篇 |
2020年 | 233篇 |
2019年 | 480篇 |
2018年 | 418篇 |
2017年 | 520篇 |
2016年 | 497篇 |
2015年 | 449篇 |
2014年 | 414篇 |
2013年 | 726篇 |
2012年 | 465篇 |
2011年 | 461篇 |
2010年 | 467篇 |
2009年 | 431篇 |
2008年 | 442篇 |
2007年 | 439篇 |
2006年 | 439篇 |
2005年 | 343篇 |
2004年 | 234篇 |
2003年 | 191篇 |
2002年 | 184篇 |
2001年 | 119篇 |
2000年 | 111篇 |
1999年 | 71篇 |
1998年 | 32篇 |
1997年 | 30篇 |
1996年 | 21篇 |
1995年 | 25篇 |
1994年 | 23篇 |
1993年 | 19篇 |
1992年 | 20篇 |
1991年 | 8篇 |
1990年 | 20篇 |
1989年 | 13篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 3篇 |
1985年 | 11篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 9篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1974年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有8767条查询结果,搜索用时 62 毫秒
11.
A model for the analysis of paired comparison data is presented which combines features of the BTL-model with features of the Unfolding model. The model is metric, mathematically tractable, and has an exact algebraic solution. Since it is multidimensional and allows for individual differences, it is thought to be more realistic for some choice situations than either the Thurstone model or the BTL-model. No claim is made that the present model will be appropriate for all conceivable choice situations. Rather, it is argued that the fact that it is explicitly falsifiable is a point in its favor.This work was supported by a grant of the United States Public Health Service (1 R03 MH19139 01 MSM) and a David Ross (XR) grant of the Purdue Research Foundation (PRF 2132), both of which are gratefully acknowledged. We also owe thanks to Dr. Terry Cooper, whose careful scrutiny of an earlier draft of this paper allowed us to reduce the number of errors from n to n-1. 相似文献
12.
临床经验对诊断的双重作用及改造 总被引:1,自引:0,他引:1
文中用辩证唯物主义的观点,阐述了临床经验的定义、来源及指导实践过程中的意义,指出其具有促进诊断和引起误诊的双重作用,并用临床病历例子详细说明其双重作用的形式、导致结果及产生的原因。指出临床经验的双重作用在临床工作中的重要性及局限性,提出对经验的改造完善途径,以能充分表现出其促进诊断的作用,而最大限度降低其导致误诊的程度,发挥在临床工作中的良性作用。 相似文献
13.
Li FP 《Ethics & behavior》1995,5(2):193-196
Case vignette: sharing unanticipated genetic information. The Questor family has experienced an unusual number of malignancies in the past two generations and has been advised by an oncologist that the p53 oncogene known as Li-Fraumeni Syndrome may be present in the family genome. The option of predictive genetic testing has been raised and several branches of the family have chosen to undergo screening to determine whether they are at risk for cancer because of the gene. Roger and Liz Questor have arranged for screening of themselves and their three children, ages 12, 10, and 7. The couple has, by all appearances, been happily married for 14 years. None of the family members are found to carry the oncogene; however, the geneticist conducting the analyses has made an interesting incidental discovery. The 10-year-old child is not the biological progeny of Roger Questor. Although the 12- and 7-year-olds are clearly the biological children of the couple, it is evident that the 10-year-old born to Liz Questor was fathered by a person other than Roger. What are the ethical obligations of the geneticist with respect to any sharing or disclosure of the information that has been discovered incidentally? What course of action, if any, do you recommend? 相似文献
14.
15.
Ping Li 《Attention, perception & psychophysics》1996,58(4):571-586
Three experiments with 60 native Chinese speakers were conducted to examine the temporal structure of spoken sentence comprehension in Chinese. In the two sentence-gating experiments, listeners heard sentence fragments of various sizes, either successively or individually, and decided on the agent role of the sentence. In the agent-naming experiment, listeners repeated aloud the sentence agent upon hearing the sentence. Converging evidence was derived from these experiments indicating the usefulness of sentence gating in tapping into the temporal structure of comprehension and in evaluating listeners’ comprehension on the basis of partial information. Results from these experiments show that partial sentence information plays a very important role in Chinese sentence comprehension, and that Chinese listeners integrate incomplete and ungrammatical sentence fragments by reference to complete and grammatical models in the language. It is argued that these processing characteristics reflect properties of the Chinese language in which few morphological, grammatical, and syntactic constraints are placed on the relationships between sentence constituents. 相似文献
16.
快速眼动相(REM)睡眠剥夺对大鼠记忆巩固的影响 总被引:2,自引:0,他引:2
本实验应用小站台水环境技术剥夺大鼠快速眼动相(REM)睡眠,比较了在学习后不同时间剥夺REM睡眠对记忆巩固的影响异同,结果证明:大鼠在学习后,立即剥夺REM睡眠24小时对记忆巩固明显不利;如在立即剥夺REM睡眠24小时后再让其恢复自由睡眠24小时,记忆成绩无明显改善;学习后允许自由睡眠24小时对记忆巩固明显有利;如在自由睡眠24小时后再行REM睡眠剥夺24小时,记忆成绩仍保持良好。说明学习后一段时间自由睡眠对于记忆的巩固是重要的,剥夺REM睡眠对于记忆的巩固明显不利。 相似文献
17.
5—13岁儿童空间认知发展的研究——判别相等面积的再探 总被引:2,自引:0,他引:2
本实验是《5—11岁儿童两种空间关系认知发展的实验研究》的继续,但将内部被占面积改为圆形。结果表明:儿童判别面积从直觉判断发展到推理判断之间经历一种过渡形态。表现为,在同一判别中直觉和推理活动交错;能将被占面积各部分整合成整体,但对剩余面积部分的判别受直觉因素束缚;理解等量减等量所余相等原理,但不能用来解决面临的课题等四种形式。完成这种过渡需要解决三个相互联系的问题。也再次证明儿童判别面积这种空间认知发展,在一定年龄范围存在着阶段性特点,同时儿童这种认知能力的显露程度又以课题条件难易为转移。 相似文献
18.
19.
20.