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   61513篇
  免费   2508篇
  国内免费   21篇
  64042篇
  2020年   588篇
  2019年   779篇
  2018年   1066篇
  2017年   1070篇
  2016年   1143篇
  2015年   828篇
  2014年   967篇
  2013年   4557篇
  2012年   1826篇
  2011年   1994篇
  2010年   1233篇
  2009年   1223篇
  2008年   1780篇
  2007年   1787篇
  2006年   1632篇
  2005年   1447篇
  2004年   1333篇
  2003年   1258篇
  2002年   1348篇
  2001年   2004篇
  2000年   1985篇
  1999年   1491篇
  1998年   728篇
  1997年   635篇
  1996年   634篇
  1993年   563篇
  1992年   1259篇
  1991年   1176篇
  1990年   1147篇
  1989年   1048篇
  1988年   1031篇
  1987年   987篇
  1986年   1057篇
  1985年   1070篇
  1984年   893篇
  1983年   816篇
  1982年   590篇
  1981年   588篇
  1979年   957篇
  1978年   689篇
  1975年   786篇
  1974年   838篇
  1973年   933篇
  1972年   786篇
  1971年   739篇
  1970年   657篇
  1969年   685篇
  1968年   876篇
  1967年   798篇
  1966年   667篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
The concepts of informed consent and surveillance of human research designed to protect human subjects is commendable. The regulations of the Institutional Review Board (IRB) are having a major impact on clinical cancer research. There is greater administrative time needed of the investigator, the mechanisms of patient care have become cumbersome and some patients reject optional medical management that could be life saving. IRB regulations must be flexible to meet the needs of human subjects as well as those of the clinical investigator.  相似文献   
992.
Prior surgical implantation of a venous catheter sensitized rats to coldimmobilization stress. Three of six catheterized females succumbed during the stress. The remaining rats fell into two groups in terms of their core temperature at the end of the stress period: Male uncatheterized rats had higher temperatures than rats in the other three groups. No relation was found between catheter patency and magnitude of hypothermia. Degree of gastric disease paralleled the core temperature findings in that the male uncatheterized rats had significantly fewer gastric erosions than the rats in the other three groups. Additionally, a robust effect of gender was found with uncatheterized females showing more hypothermia and more gastric disease than uncatheterized males. A subsequent experiment was conducted to evaluate whether anesthesia or wearing the protective spring was responsible in part for the sensitization seen. Here, the gender difference was less although females consistently averaged lower core temperatures after stress than did males. Despite similar core temperatures after stress, females that were prepared with the protective spring apparatus developed more gastric disease than female controls or similarly treated males. Thus, the additional sensitization exhibited by females in the first experiment may relate to the fact that both catheterization and the taping procedure were sensitizers while only catheterization was a sensitizer for males.  相似文献   
993.
Recent studies have begun to test certain fundamental assumptions underlying popular models of feature perception. This research is continued here. It was discovered that every basic assumption that was open to test in the present study was disconfirmed. However, several new characteristics of line and curve feature perception were discovered: (1) Feature perception sensitivity was inversely related to the number of features present in a stimulus pattern, and the decision criteria for reporting a feature decreased with the number of features contained in a pattern; (2) the decrements in sensitivity reported in (1) were greater for features lying inside a pattern than for those on the exterior; and (3) feature perception sensitivity actually improved if another feature was known to be correctly perceived during the same trial. Likewise, feature sensitivity decreased if another feature was missed on any trial. At the present time, a system that first extracts global and then local (more detailed) featural information provides a basis that qualitatively accounts for our findings and is also compatible with several other studies in the literature.  相似文献   
994.
T J Silber 《Adolescence》1984,19(74):493-499
The period of youth and adolescence has been shown to have continuous demographic growth in the developing world. Young nations thus have to contend with the specific health needs of teenagers and young adults. This is illustrated by an analysis of the health-care needs of Brazilian adolescents. The issues highlighted here are adolescent morbidity and mortality, current delivery of adolescent health care, and future directions of adolescent programs in Brazil.  相似文献   
995.
This study provides a reexamination of the role of different decisional strategies in facilitating progress in occupational decision making. Although the assumptions that a rational decision making style is the preferred mode of vocational functioning has been endorsed in a variety of career theories and interventions, there has been conflicting evidence about the validity of this assumption. To examine the role of different decisional approaches in the progress of making an occupational decision, the rational, intuitive, and dependent decision making style scores of 71 undergraduate students were used to predict progress in occupational decision making. The results of the regression analyses failed to provide support for the assumption that a rational style is the most effective in accomplishing this careerrelated task, but indicated strong support for the conclusion that the use of dependent decisional strategies is damaging, particularly in early stages of the decisional process.  相似文献   
996.
Though many studies have examined the predictive power of expressed choices versus that of measured interests, fewer have been concerned with the relationship between the degree to which choices and interests agree and later persistence in an expressed choice. This study explored that relationship, using longitudinal data for 7706 college students and 1372 employed persons. Four levels of congruence between expressed choice and measured interests were identified. Results indicated that persistence in an expressed choice increases systematically as congruence between choice and interests increases. Implications for counselors are noted.  相似文献   
997.
The authors recently proposed that adverse effects of material rewards on Wechsler subscale performance may be the result of a reward-produced developmental regression. The present study further explores that idea through an attempt to replicate earlier findings with adults and to extend the inquiry to children. Selected Wechsler subscales were administered to 32 subjects at each of three ages (5, 10, and 18 years) under either reward or nonreward conditions. Subscales were chosen to represent both algorithmic and heuristic types of tasks. Reward and nonreward groups (8 males and 8 females per group at each age) were matched initially on age and ability. For adults, consistent with earlier findings, reward had an adverse effect on performance on the heuristic subscales and tended to facilitate performance on the algorithmic subscales. However, rewards generally had no effect at the fourth-grade level and had a reverse effect at the nursery school level, i.e., rewards facilitated heuristic and hampered algorithmic performance. These findings appear to be more consistent with an explanation based on developmental regression than on any available alternative mechanism.  相似文献   
998.
Full-time employed (N = 255), partly employed (N = 48), and unemployed (N = 43) male and female university graduates completed a questionnaire that included measures designed to assess expected job levels and current job levels and two measures of potential social action (willingness to volunteer actions and hours to a fictional Campaign to Assist Unemployed Youth). Comparisons between groups and the results of multiple regression analyses provided mixed support for the prediction that larger negative gaps between expected and current employment status would be associated with a greater willingness to assist the Campaign. The unemployed respondents tended to volunteer more actions and more hours to the Campaign than did the other two groups. A multiple regression analysis showed that the current level by expected level interaction term was statistically significant as predicted, but only for the fully employed graduates. Within the full-time employed group, female graduates and those from the humanities/social sciences/education schools expressed more willingness to assist the Campaign than did male graduates and those from the sciences/medicine schools of the university. Results were discussed in relation to current research on relative deprivation and reported affect and to recent studies of job satisfaction.  相似文献   
999.
A comparison of the WISC-R and the Woodcock-Johnson Psycho-Educational Educational Battery (W-J) was made for children with regular and learning-disabled (LD) class placement. The W-J and Wechsler Intelligence Scale for Children-Revised (WISC-R) evidence low to moderate correlations and significant mean differences, indicating that the two tests are measuring somewhat different abilities to somewhat differing degrees. W-J—WISC-R correlations for the regular students exceed those of the LD students in the greater majority of the cases. Rank ordering of the WISC-R subtests and the W-J clusters indicate, as might be expected, that the LD students fare the worst in the WISC-R academic subtests (Arithmetic, Information and Vocabulary) and in the W-J academic clusters. More research needs to be conducted with the W-J before it should be adopted for use in the placement of exceptional children.  相似文献   
1000.
As an example of the development of an early school psychology program in the Southwest, the beginning of Child Study and Consultation Service is described. The unique aspect of this program undoubtedly had to do with its relationship to a demonstration mental health center and a consultation program started in several elementary school districts in the area. Beginning with a consortium of five school districts, it was later expanded to include 16 school districts with a staff of 15 doctoral-level school psychologists. This account also describes the author's involvement with the Division of School Psychology and some of the major issues facing the division in the late 1950s and 1960s. An attempt is made to show how the author's educational and work experiences contributed to the philosophy, policies, and practices of school psychology.  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