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   1990篇
  免费   91篇
  国内免费   17篇
  2098篇
  2025年   2篇
  2024年   24篇
  2023年   50篇
  2022年   31篇
  2021年   58篇
  2020年   96篇
  2019年   133篇
  2018年   104篇
  2017年   100篇
  2016年   115篇
  2015年   71篇
  2014年   107篇
  2013年   360篇
  2012年   78篇
  2011年   68篇
  2010年   60篇
  2009年   80篇
  2008年   92篇
  2007年   74篇
  2006年   55篇
  2005年   60篇
  2004年   36篇
  2003年   19篇
  2002年   15篇
  2001年   11篇
  2000年   11篇
  1999年   8篇
  1998年   9篇
  1997年   4篇
  1996年   10篇
  1995年   6篇
  1994年   8篇
  1993年   4篇
  1992年   2篇
  1990年   1篇
  1989年   1篇
  1986年   1篇
  1985年   14篇
  1984年   11篇
  1983年   12篇
  1982年   7篇
  1981年   17篇
  1980年   10篇
  1979年   9篇
  1978年   9篇
  1977年   14篇
  1976年   3篇
  1975年   10篇
  1974年   7篇
  1973年   10篇
排序方式: 共有2098条查询结果,搜索用时 0 毫秒
891.
Vocalizations are preceded by slow EEG waves over inferior frontal scalp regions, but some controversy exists as to whether these slow potentials are left-lateralized as a function of speech. In this study both speech and non-speech vocalizations were studied, under conditions of repetitive and variable production. Averaged responses over the speech musculature, including the temporalis, masseter, orbicularis oris, and mylohyoid muscles, as well as the eyes and tongue, were calculated simultaneously with scalp EEG averages. The responses of the temporalis and masseter muscles, as well as that of the tongue, were correlated with EEG sites at specific latencies prior to speech, suggesting that no part of the inferior frontal EEG record was free from myogenic confounds. In addition, all significant EEG differences between speech and non-speech conditions were subsequently eliminated by covariance analysis, using selected muscle channels as covariates. Previous reports of asymmetrical “speech potentials” in the EEG probably reflected a combination of several myogenic confounds.  相似文献   
892.
This paper demonstrates the feasibility of using the penalty function method to estimate parameters that are subject to a set of functional constraints in covariance structure analysis. Both types of inequality and equality constraints are studied. The approaches of maximum likelihood and generalized least squares estimation are considered. A modified Scoring algorithm and a modified Gauss-Newton algorithm are implemented to produce the appropriate constrained estimates. The methodology is illustrated by its applications to Heywood cases in confirmatory factor analysis, quasi-Weiner simplex model, and multitrait-multimethod matrix analysis.The author is indebted to several anonymous reviewers for creative suggestions for improvement of this paper. Computer funding is provided by the Computer Services Centre, The Chinese University of Hong Kong.  相似文献   
893.
Three female human subjects pressed a button for monetary reinforcement in a range of variable-interval schedules specifying different frequencies of reinforcement. On alternate days, responding was also punished (by subtracting money) according to a variable-ratio 34 schedule. In the absence of punishment, rate of responding was an increasing negatively accelerated function of reinforcement frequency; the relationship between response rate and reinforcement frequency conformed to Herrnstein's equation. The effect of the punishment schedule was to suppress responding at all frequencies of reinforcement. This was reflected in a change in the values of both constants in Herrnstein's equation: the value of the theoretical maximum response-rate parameter was reduced, while the parameter describing the reinforcement frequency corresponding to the half-maximal response rate was increased.  相似文献   
894.
Abstract

Preventive strategies for menopausal women to reduce the risks for osteoporosis and cardiovascular disease has been the focus of considerable attention, but understanding of mid-aged women's behavioural risk factors for these diseases is meagre. The current study describes a range of health-related behaviours and their psychosocial correlates, in a sample of 45-year old women, recruited from five general practices and assessed by postal survey (N=106, response rate 60%). Results suggest that health promotion for this group might best focus upon increases in regular exercise, calcium intake and breast awareness, and decreases in cigarette and caffeine consumption. The behaviours assessed were generally not inter-related. However, several associations were identified between behaviours and health and psychosocial variables. The main ones were the association between menopausal status and smoking, and the relationship between body weight, self-esteem and physical exercise. It is argued that the menopause transition can be an opportunity for preventive work.  相似文献   
895.
Abstract

This article is concerned with examining Kant's derivation of the various formulae of his Categorical Imperative. It is in agreement with Paton in maintaining that Kant actually mentions five formulae. But it is not in agreement with him, and some others, in maintaining that they are ultimately reducible to three. Nor is it in agreement with those who maintain that they are ultimately reducible to just one. According to the present article, they are ultimately reducible to two: that about a moral law being a universal law; and that about a moral law involving treating human beings as ends in themselves.  相似文献   
896.
On Chimeras     
Bernard E. Rollin 《Zygon》2007,42(3):643-648
This essay is a critical response to Neville Cobbe's article “Cross‐Species Chimeras: Exploring a Possible Christian Perspective.” New technologies, particularly biotechnologies, raise major concerns in society. In the absence of good ethical thinking on these issues, bad ethical thinking becomes regnant. Two common types of bad ethical thinking are (1) confusing whatever disturbs people with genuine ethical issues and (2) confusing religious issues with ethical ones. Cobbe's article commits the former type of error with regard to the possibility of a mouse created with human brain neurons. I analyze and discuss that error and also raise questions about Cobbe's attempt to analyze the creation of chimeras from a Christian perspective.  相似文献   
897.
This study compared the sentence production abilities of individuals with Broca's and Wernicke's aphasia in an attempt to explore the extent to which impaired lexical retrieval impedes sentence production. The ability to produce active and passive reversible and non-reversible sentences was examined when varying amounts of lexical information was provided. The results showed that both Wernicke's and Broca's aphasic individuals were impaired in passive sentence production and that these difficulties were not overcome when lexical cues (the relevant nouns and uninflected verb) were provided. However when auxiliary and past tense morphemes were provided along with the verb stem, production of passive sentences improved drastically for both groups. Analysis of error patterns, however, revealed differences between the two groups, suggesting that Broca's aphasic subjects may find passive sentences difficult due to problems with retrieving the relevant grammatical morphemes. Subjects with Wernicke's aphasia may have been unable to automatically access the passive sentence structure.  相似文献   
898.
The problem of the irreversibility’s origin in thermodynamic processes occupies a distinguished place among many and lasting attempts by researchers to derive irreversibility from molecular-mechanical principles. However, this problem is still open and no universally accepted solution may be given during any course. In this paper, I shall try to show that the examining of Maxwell’s demon thought experiment may provide insight into the difficulties that emerge, looking for this origin because: (i) it is connected with the notion of irreversibility, and (ii) one of its functions is that of the “reversibility objection.” In order to illustrate this point, I study Boltzmann’s approach to the problem of a molecular-mechanical interpretation of irreversibility and I show that an auxiliary assumption (the selected direction of time) is responsible for producing irreversibility. But this result is accordant with the predictions of Maxwell’s demon thought experiment: the assumptions of this kind are not dictated by molecular-mechanical principles but are separate input in the model-systems used.
Aspasia S. MoueEmail: Email:
  相似文献   
899.
This essay explores changing attitudes towards male caregivers in postwar America to understand conceptions of prepubescent gender and sexuality. While the 1950s have been viewed as a period of rigid gender conventions, the demands of a baby boom generation allowed men unexpected roles as caregivers. In the 1960s and 1970s, challenges to the status quo along with fears of female-headed households encouraged men to move into the field of child care, but this was particularly short lived. Political backlash and a failing economy turned male daycare workers into suspects, revealing the ambiguity that so often distorts children’s interactions with men.
Julie A. WillettEmail:
  相似文献   
900.
In her (1996) Kadri Vihvelin argues that autoinfanticide is nomologically impossible and so that there is no sense in which time travelers are able to commit it. In response, Theodore Sider (2002) defends the original Lewisian verdict (Lewis 1976) whereby, on a common understanding of ability, time travelers are able to kill their earlier selves and their failure to do so is merely coincidental. This paper constitutes a critical note on arguments put forward by both Sider and Vihvelin. I argue that although Sider’s criticism starts out promisingly he doesn’t succeed in establishing that Vihvelin’s analysis fails, because (a) he neglects to rule out a class of counterfactuals to which Vihvelin’s sample-case may belong; and (b) (together with Lewis) he is wrong to suggest that future facts are irrelevant in the evaluation of time travelers’ abilities. I show instead that Vihvelin’s argument is viciously circular, indicating that even if there are nomological constraints on autoinfanticide these cannot be established a priori.
Ira KiourtiEmail:
  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