全文获取类型
收费全文 | 14124篇 |
免费 | 607篇 |
国内免费 | 13篇 |
出版年
2023年 | 75篇 |
2021年 | 119篇 |
2020年 | 216篇 |
2019年 | 267篇 |
2018年 | 362篇 |
2017年 | 361篇 |
2016年 | 380篇 |
2015年 | 275篇 |
2014年 | 352篇 |
2013年 | 1567篇 |
2012年 | 626篇 |
2011年 | 665篇 |
2010年 | 400篇 |
2009年 | 430篇 |
2008年 | 580篇 |
2007年 | 575篇 |
2006年 | 584篇 |
2005年 | 531篇 |
2004年 | 496篇 |
2003年 | 513篇 |
2002年 | 503篇 |
2001年 | 253篇 |
2000年 | 236篇 |
1999年 | 226篇 |
1998年 | 204篇 |
1997年 | 218篇 |
1996年 | 199篇 |
1995年 | 176篇 |
1994年 | 164篇 |
1993年 | 158篇 |
1992年 | 146篇 |
1991年 | 155篇 |
1990年 | 136篇 |
1989年 | 130篇 |
1988年 | 93篇 |
1987年 | 120篇 |
1986年 | 130篇 |
1985年 | 164篇 |
1984年 | 164篇 |
1983年 | 143篇 |
1982年 | 137篇 |
1981年 | 149篇 |
1980年 | 126篇 |
1979年 | 110篇 |
1978年 | 123篇 |
1977年 | 111篇 |
1976年 | 113篇 |
1975年 | 98篇 |
1974年 | 107篇 |
1973年 | 89篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
221.
Private and public sector managers were compared regarding their job characteristics and organizational commitment. We hypothesized that job characteristics would be positively related to commitment and that sector would moderate that relationship. Moderated regression analyses revealed partial support for both hypotheses. The existence of clarity and challenge were positively related to commitment. Job characteristics demonstrated a stronger relationship with commitment among private sector managers. Explanations for these findings and directions for future research are discussed. 相似文献
222.
223.
David Turnbull 《Knowledge, Technology, and Policy》1993,6(3-4):29-54
This article argues that all knowledge is inherently local and that localness provides the basis for comparison between indigenous scientific traditions or knowledge production systems. As collective bodies of knowledge, many of the significant differences between knowledge production systems lie in the work involved in creating assemblages from differing practices. Much of the work can be seen in the social strategies and technical devices employed in creating equivalences and connections whereby otherwise heterogeneous and isolated knowledges are enabled to move in space and time from the local site and moment of their production and application to other places and times. In this way contemporary technosciences are compared with the knowledge systems of the medieval mastermasons, the Anasazi, the Inca, the Australian Aborigines and the Pacific navigators. 相似文献
224.
David Seedhouse 《Theoretical medicine and bioethics》1993,14(4):287-294
Those who would enquire into therelationship between “health conceptions” and “health care consequences” are faced with a formidable task. In order to make this challenge manageable it is necessary to define the scope of the task as precisely as possible. Are we, for instance, faced with a purely theoretical challenge; a task for applied philosophy, or must we employ multi-disciplinary methods? This paper argues that while philosophy has a central clarifying role, inquiry into the relationship between “health conceptions” and “health care organisation” can be done properly only through the combined efforts of several disciplines. Unless we are to be concerned only with abstract models it is essential to take account of the reality of health care situations. Given this it is suggested that the study of “health conceptions” is only a part of a greater task (unless all conceptions are to count as “health conceptions”). What is needed is understanding of the possible and actual purposes of health care, and detailed study of their practical implications. 相似文献
225.
It has become common for stimuli used in visual psychophysical experiments to be presented on high-resolution color cathode-ray tubes (CRTs) such as the Barco CDCT 6551. These enable a flexibility of color, spatial-frequency content, temporal-frequency content, duration, size, and position that is not provided by most other media. CRTs are, however, not perfect; they suffer from the effects of temporal instability, spatial variability, lack of phosphor constancy, gun interdependence, and gun nonlinearity. This paper describes methods of assessing these aspects of monitor performance with respect to how significant each may be in psychometric terms. Although every application of CRT use in visual psychophysics is different, some general rules can be formulated to help ensure that unwanted effects are kept to a minimum. For the CRT used in this study (Barco CDCT 6551), a warm-up time of 30-45 min is necessary before chromatic and luminous stability ensues. Restriction of individual gun outputs to within 10%-90% of the possible range ensures that the effects of gun interdependence and lack of phosphor constancy are negligible. Calibration methods dealing with the linearization of gun output are also discussed. 相似文献
226.
比较研究-影响中美儿童计算能力差异的认知因素 总被引:2,自引:0,他引:2
本研究要确定中美儿童基本计算技能的差异是否与他们使用的解题策略和基本加工过程的速度有关。为此,对中美两国的一年级儿童进行了书面计算能力测验,以及一组计算机呈现的加法作业。中国儿童在计算能力测验上表现出3:1的操作优势。中美儿童使用的解题策略种类一样,但是,中国儿童在策略综合运用的发展程度上超过美国儿童,检索策略的加工速度也超过美国儿童。显然,策略运用和加工速度的差异促成了中国儿童在计算能力测验上的优势. 相似文献
227.
Tolbutamide has previously been shown to amplify the pressor effects of “exogenous” catecholamines in conscious dogs, possibly due to sensitization of the α1-adrenoreceptor-mediated vasoconstriction. The objective of this study was to examine if tolbutamide also amplifies the pressor effects of “endogenous” catecholamines released during psychological stress (classical Pavlovian aversive conditioning). Experiments were conducted in β-adrenoreceptor-blocked (propranolol, 1 mg/kg, i.v.) conscious dogs (n=4) trained in classical aversive conditioning. Conditioning was accomplished by following a tone (CS+) with a 1/2 second shock; another tone (CS-) was not followed by any shock and served as control. With saline pretreatment, aversive conditioning (i.e., CS+) increased mean arterial pressure (MAP) only by approximately 4.7% when compared to CS-, whereas with tolbutamide (45 mg/kg, i.v.) pretreatment, the increase in MAP induced by CS+ beyond what was induced by the CS- (approximately 6.2%) was significantly (p<0.05) larger than that with saline pretreatment. In isolated canine femoral arterial segments (n=4), the vasoconstrictor effect of phenylephrine (an α1-agonist) at 5×10?6M (which was the EC50 value) was amplified by 2×10?2M of tolbutamide from 54.0±2.0% to 66.9±2.1%. In conclusion, tolbutamide amplifies the pressor effects of “endogenous” catecholamines in conscious dogs, possibly by sensitization of the α1-adrenoreceptor-mediated vasoconstriction. This mechanism of action is novel and has not been reported with other agents. 相似文献
228.
The effects of distractor clustering on target detection were examined in two experiments in which subjects attended to binaural tone bursts of one frequency while ignoring distracting tones of two competing frequencies. The subjects pressed a button in response to occasional target tones of longer duration (Experiment 1) or increased loudness (Experiment 2). In evenly spaced conditions, attended and distractor frequencies differed by 6 and 12 semitones, respectively (e.g., 2096-Hz targets vs. 1482- and 1048-Hz distractors). In clustered conditions, distractor frequencies were grouped; attended tones differed from the distractors by 6 and 7 semitones, respectively (e.g., 2096-Hz targets vs. 1482- and 1400-Hz distractors). The tones were presented in randomized sequences at fixed or random stimulus onset asynchronies (SOAs). In both experiments, clustering of the unattended frequencies improved the detectability of targets and speeded target reaction times, Similar effects were found at fixed and variable SO As. Results from the analysis of stimulus sequence suggest that clustering improved performance primarily by reducing the interference caused by distractors that immediately preceded the target. 相似文献
229.
David Foulkes Barbara Meier Inge Strauch Nancy H. Kerr Laura Bradley Michael Hollifield 《International journal of psychology》1993,28(6):871-891
Sixteen German-English bilinguals were studied in a sleep laboratory for four nonconsecutive nights each. Half were native English speakers living in Zürich, and half native German speakers living in Atlanta. Presleep thought samples were solicited each evening and REM dream reports each night; subjects judged the waking appropriateness of their imagined speech and language phenomena, and also identified waking sources of their dream imagery, the following mornings. Incidences of dreaming and of speech therein generally were similar to those of monolinguals. Whether sessions were conducted in German (two nights) or English (two nights) did directly influence language selection in subjects' dreams. Judged appropriateness of language selection to imagined events was very high for thought samples, and high for REM dreams. Sources for thought samples were generally consonant with the language dominant at study site; for REM dreams this relationship was considerably weaker. Judged waking appropriateness to imagined situations was more strongly related to language selection than was the language reference of the supposed sources of those situations. 相似文献
230.
David C. Geary Pierre Cormier Judith P. Goggin Patricia Estrada Melanie C. E. Lunn 《International journal of psychology》1993,28(2):185-201
Two experiments compared rates of solving simple and complex addition and multiplication problems in groups of speakers of French or English in Experiment 1 (n = 35) and Spanish or English in Experiment 2 (n = 84). Subjects were divided into groups of English unilinguals, weak bilinguals, and strong bilinguals according to their performance on a naming task. In both experiments, simple problems consisted of two single-digit numbers. At least three single-digit numbers were used for complex problems in Experiment 1 and double-digit numbers in Experiment 2. Mean solution times, particularly for complex problems, were lowest for the monolingual group, followed in turn by the weak bilingual and strong bilingual groups, but these differences were not statistically reliable in either experiment. In Experiment 2, however, componential analyses of solution times indicated that strong bilingual subjects were slower at executing the carry operation when solving complex problems, relative to the two remaining groups. Results were interpreted in terms of the relationship between bilingualism and the representation and processing of numerical information. 相似文献