全文获取类型
收费全文 | 84654篇 |
免费 | 3350篇 |
国内免费 | 34篇 |
专业分类
88038篇 |
出版年
2020年 | 810篇 |
2019年 | 1079篇 |
2018年 | 1458篇 |
2017年 | 1542篇 |
2016年 | 1565篇 |
2015年 | 1148篇 |
2014年 | 1329篇 |
2013年 | 6502篇 |
2012年 | 2448篇 |
2011年 | 2699篇 |
2010年 | 1735篇 |
2009年 | 1699篇 |
2008年 | 2421篇 |
2007年 | 2379篇 |
2006年 | 2186篇 |
2005年 | 1907篇 |
2004年 | 1770篇 |
2003年 | 1732篇 |
2002年 | 1783篇 |
2001年 | 2770篇 |
2000年 | 2726篇 |
1999年 | 2046篇 |
1998年 | 994篇 |
1997年 | 863篇 |
1996年 | 851篇 |
1992年 | 1747篇 |
1991年 | 1626篇 |
1990年 | 1597篇 |
1989年 | 1453篇 |
1988年 | 1416篇 |
1987年 | 1403篇 |
1986年 | 1436篇 |
1985年 | 1501篇 |
1984年 | 1258篇 |
1983年 | 1081篇 |
1982年 | 813篇 |
1981年 | 802篇 |
1979年 | 1305篇 |
1978年 | 940篇 |
1977年 | 799篇 |
1975年 | 1082篇 |
1974年 | 1168篇 |
1973年 | 1286篇 |
1972年 | 1056篇 |
1971年 | 967篇 |
1970年 | 862篇 |
1969年 | 931篇 |
1968年 | 1145篇 |
1967年 | 1019篇 |
1966年 | 960篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
Sara J. Shettleworth 《The Quarterly Journal of Experimental Psychology Section B: Comparative and Physiological Psychology》1981,33(4):241-255
Are different responses differentially associable with their consequences? An overshadowing design was used to try to answer this question for three responses previously studied in golden hamsters. In Experiment I, scrabbling was rapidly suppressed by electric shock punishment, and it overshadowed a tone which occurred between scrabbling and shock. In Experiment II, no evidence of response-shock association was obtained when open rearing was the punished response, and open rearing did not overshadow the tone. Punishment had some effect on face washing, but there was no statistically significant overshadowing with this response. These results are consistent with the idea that differences in punishment suppression among these three responses have an associative basis. They also demonstrate the usefulness of a novel paradigm for studying “preparedness” of response-reinforcer associations. 相似文献
43.
Kristine L S P McVea 《Health psychology》2006,25(5):558-562
OBJECTIVE: This report reviews the evidence that informs the role of health and mental health care providers in addressing youth smoking cessation. DESIGN: Qualitative literature review. RESULTS: Physicians do not consistently screen adolescents for tobacco use and fail to provide recommended cessation advice. Challenges to addressing smoking cessation include the need for procedures to ensure confidentiality and the existence of competing demands to provide other services. Few published studies have specifically addressed the effectiveness of clinical interventions. Interventions that require return visits or follow-up phone contacts are technically difficult to implement in this population. Successful interventions may require resources not available in nonresearch settings. Most studies have used brief clinical intervention as a control condition, making it impossible to evaluate its effectiveness. CONCLUSION: There is little evidence that supports current clinical smoking cessation guidelines for adolescents. More research is needed to develop inexpensive, efficient clinical interventions that can provide youths access to smoking cessation help. Future challenges include reorganizing clinical systems to offer greater counseling by support staff or in electronic formats and to provide effective booster messages and follow-up care in a population that is difficult to track. 相似文献
44.
An electronic apparatus using infrared beams for monitoring the movements of individual bees under dark conditions is described. The searching behavior of workers in an arena was monitored over 2-h periods. Mean ambulatory velocity for one bee over a distance of 100 mm was 45.6±1.51 mm/sec (n=45). Thigmokinesis and temporal activity patterns are illustrated. 相似文献
45.
46.
47.
48.
49.
Reducing STD/HIV Stigmatizing Attitudes Through Community Popular Opinion Leaders in Chinese Markets
Reducing STDs and HIV/AIDS incidence requires campaigns designed to change knowledge, attitudes, and practices of risky sexual behavior. In China, a significant obstacle to such changes is the stigma associated with these diseases. Thus 1 campaign intervention strategy is to train credible community leaders to discuss these issues in everyday social venues. This study tested the effectiveness of such an approach on reducing HIV/AIDS stigma, across 2 years, from a sample of over 4,500 market vendors, in 3 conditions. Results showed an increasing growth in market communication about intervention messages, and concomitant declines in stigmatizing attitudes, across time, with the greatest changes in community popular opinion leaders, significant changes in intervention nonopinion leaders, and little change in the control markets. 相似文献
50.
Susan S Girdler Jane Leserman Robertas Bunevicius Rebecca Klatzkin Cort A Pedersen Kathleen C Light 《Health psychology》2007,26(2):201-213
OBJECTIVE: To examine dysregulation in biological measures associated with histories of abuse in women and whether women with premenstrual dysphoric disorder (PMDD) differ in their dysregulation. DESIGN: Twenty-five women meeting prospective criteria for PMDD and 42 non-PMDD controls underwent structured interview to determine abuse histories and lifetime Axis I diagnoses, excluding those with current Axis I disorders or using medications. MAJOR OUTCOME MEASURES: Plasma cortisol and norepinephrine (NE), heart rate (HR), blood pressure (BP), and vascular resistance index (VRI) were assessed at rest and in response to mental stress. RESULTS: A greater proportion of PMDD women had prior abuse compared with non-PMDD women. Regardless of PMDD status, all abused women had lower plasma NE and higher HRs and tended to have lower plasma cortisol at rest and during stress. Abused women also reported more severe daily emotional and physical symptoms. Greater VRI and BP at rest and during stress were seen only in PMDD women with abuse. CONCLUSION: There is persistent dysregulation in stress-responsive systems in all abused women that cannot be accounted for by current psychiatric illness or medications, and PMDD women may be differentially more vulnerable to the impact of abuse on measures reflecting alpha-adrenergic receptor function. 相似文献