全文获取类型
收费全文 | 94061篇 |
免费 | 4836篇 |
国内免费 | 9289篇 |
专业分类
108186篇 |
出版年
2023年 | 1156篇 |
2022年 | 1361篇 |
2021年 | 815篇 |
2020年 | 1229篇 |
2019年 | 1345篇 |
2018年 | 1670篇 |
2017年 | 859篇 |
2016年 | 955篇 |
2015年 | 791篇 |
2014年 | 2059篇 |
2013年 | 1571篇 |
2012年 | 7857篇 |
2011年 | 9537篇 |
2010年 | 3613篇 |
2009年 | 3049篇 |
2008年 | 8429篇 |
2007年 | 8054篇 |
2006年 | 7393篇 |
2005年 | 6202篇 |
2004年 | 5509篇 |
2003年 | 5104篇 |
2002年 | 4523篇 |
2001年 | 3278篇 |
2000年 | 4187篇 |
1999年 | 1768篇 |
1998年 | 620篇 |
1997年 | 590篇 |
1996年 | 544篇 |
1995年 | 599篇 |
1994年 | 589篇 |
1993年 | 516篇 |
1992年 | 483篇 |
1991年 | 458篇 |
1990年 | 485篇 |
1989年 | 457篇 |
1988年 | 593篇 |
1987年 | 578篇 |
1986年 | 438篇 |
1985年 | 533篇 |
1984年 | 437篇 |
1983年 | 455篇 |
1982年 | 367篇 |
1981年 | 353篇 |
1958年 | 643篇 |
1957年 | 523篇 |
1956年 | 448篇 |
1955年 | 425篇 |
1954年 | 334篇 |
1953年 | 304篇 |
1952年 | 292篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
241.
242.
243.
The global threat of AIDS requires massive public educational campaigns that employ social and behavioral sciences such as psychology, sociology, and anthropology because sexual behavior possesses a social dimension. Research is concerned with what stimulates behavioral change, what are the prerequisites of learned behavior, and what enables personal control over the environment and future. Educational programs designing strategies for AIDS prevention require social and behavioral science content and input. Interdisciplinary provides general principles with psychological, social, and cultural aspects of human behavior. Without knowledge about psychological processes (thinking, perception, speech, aspects of personality, and interactive behavior) and social processes (economic conditions, social networks, and resources) which are implicated in health problems and also in AIDS, these educational programs cannot produce credible results. These programs and their subsequent implementation require their application in practice in a systemic and consistent fashion. Evaluations are also needed to make sure that the applied processes for behavioral change conform to methodological criteria that ensure their effectiveness. These types of studies are more complex than pure AIDS research which is aimed at finding a cure. 相似文献
244.
The Companeros model of HIV infection prevention in Ciudad Juarez, Mexico, is presented as conceived by the National Institute of Drug Abuse (NIDA). 518 women who were IV drug users, sexual partners of drug addicts, or prostitutes were requested to participate, and 232 consented. Initial and follow-up AIDS assessments were utilized along with an assessment of sociodemographic variables, including knowledge, sexual behavior, use and abuse of drugs, and previous health history. Educative sessions about AIDs and sexually transmitted diseases (STDs) included group discussions and interaction, video watching, personal experiences, and sociodramas. 61% of prostitutes were 29, 12.6% were 13-19 years old, 31.1% were aged 30-39, and 8.9% were 40. 11% had no formal education, 58% had 6 years of primary and part of 3 years of secondary education, only 18.6% completed secondary education; and 13% had higher education. 19% lived in a hotel or shelter. Family disintegration reached 44%; these women did not live with their children. Only 5.2% thought they had excellent health, 51% said they had good health, 31% stated they had average health, and 12% admitted having had health problems. 14.6% had genital ulcers, 1.3% had herpes, 15% had gonorrhea, and 10% had syphilis. Since IV drug use among these women was almost nonexistent sexual relations constituted the principal risk factor. Responses to a questionnaire showed that the most frequent sexual behavior was vaginal penetration followed by fellatio; anal penetration was less common. 34.9% of the women practiced fellatio without protection, 16.3% had anal intercourse without protection. The proportion of AIDS cases in Mexico in women of reproductive age was growing at an exponential rate, possible because of misinformation about AIDS, a history of STDs, and a low rate of condom use. 相似文献
245.
246.
立体视觉的心理物理和VEP比较研究 总被引:2,自引:0,他引:2
心理物理试验是研究立体视觉的主要方法。70年代VEP开始用于体视研究,并取得许多结果。由于VEP信号复杂,这些结果不能令人满意。本文使用心理物理试验和VEP对比方法对体视加以研究。我们的结果是:VEP波形中第一个正峰与刺激图形的亮度有关;N_2峰和P_3峰的潜伏期对判断体视存在与否有重要价值;本试验确定N_2峰潜伏期在体视存在时约为240ms—280ms,无体视存在时约为290ms—310ms;P_3峰潜伏期在体视存在时约为280ms—310ms,无体视存在时约为340ms—360ms;体视存在时的VEP与无体视存在时的VEP的互相关系数小于0.1;有体视的VEP其功率谱密度在8Hz附近有一峰;心理物理试验中使用强制选择得到的结果从VEP波形比较中可以确认是可靠的;有体视的VEP其N_2和P_3的潜伏期随视差变化呈现规律性改变。 相似文献
247.
248.
量词肯定句和否定句的理解 总被引:6,自引:2,他引:4
本研究试图探索人们对舍有“所有”、“每一个”、“有一些”等量词的肯定句、否定句和双重否定句的理解。要求成人被试尽快判断呈现在计算机屏幕上的句子和哪一幅图画的内容相符。结果表明,影响反应时的因素为(1)句子的表层结构和它的底层意义的一致程度;(2)句子的意义和从图画中得出的命题的一致程度;(3)句子中使用的量词。结果还表明,否定句的判断时间不一定全都比肯定句的长。 相似文献
249.
250.
The construct accessibility model (CAM) holds that constructs are most likely to influence behavior when they are accessible in memory. While the theory of reasoned action sees intention as an important determinant of behavior, the CAM predicts that the intention to act upon a given health behavior is not likely to be acted upon unless the intention is in an accessible state. Therefore, people who frequently talk about or think about using condoms are likely to have condom related constructs available and use them when needed. This paper reports findings from the pilot phase of a project to identify beliefs which influence condom use in Hispanic and African-American youth living in Detroit. 15 male and 15 female Hispanics and 17 male and 17 female African-Americans aged 15-21 years of mean and median age 18.5, were interviewed face-to-face in 1989 with the goal of identifying condom beliefs which may influence their condom use. 80-82% of male participants, 53% of Hispanic females, and 100% of Black females had experienced sexual intercourse, with age at first intercourse ranging between 13.1 and 16.5 years. 88% of Black women and 7% of Hispanic women were pregnant at the interview. Regarding participants' level of preventive knowledge, all but 1 recently immigrated Hispanic female knew HIV was transmitted by needles and sexual intercourse. 87% of Hispanics and 94% of African-Americans responded that condoms protect against AIDS, but only 13% of Hispanics and 47% of African-Americans knew that nonlatex condoms do not. Some participants expressed concern that condoms reduce sensitivity and/or break during intercourse. Controlling for sexual activity, 25% of Hispanic females, 83% of Hispanic males, 71% of African-American females, and 80% of African-American males had ever used a condom; no Hispanic and 14% of Blacks reported using them consistently in the 12 month period preceding the interview. With 100% of African-American males and 97% of Black females reporting thinking about using condoms compared to 80% of Hispanics, the study findings suggest that condom intentions are more accessible in African-Americans than among Hispanics. 相似文献