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   16398篇
  免费   845篇
  国内免费   136篇
耳鼻咽喉   116篇
儿科学   433篇
妇产科学   284篇
基础医学   1760篇
口腔科学   140篇
临床医学   2848篇
内科学   1221篇
皮肤病学   147篇
神经病学   4249篇
特种医学   168篇
外科学   734篇
综合类   1670篇
一般理论   1篇
预防医学   1355篇
眼科学   70篇
药学   1512篇
  4篇
中国医学   497篇
肿瘤学   170篇
  2024年   46篇
  2023年   332篇
  2022年   625篇
  2021年   852篇
  2020年   744篇
  2019年   720篇
  2018年   674篇
  2017年   585篇
  2016年   601篇
  2015年   489篇
  2014年   1160篇
  2013年   1331篇
  2012年   1062篇
  2011年   1329篇
  2010年   920篇
  2009年   843篇
  2008年   905篇
  2007年   736篇
  2006年   551篇
  2005年   425篇
  2004年   352篇
  2003年   316篇
  2002年   232篇
  2001年   201篇
  2000年   139篇
  1999年   114篇
  1998年   99篇
  1997年   93篇
  1996年   74篇
  1995年   74篇
  1994年   64篇
  1993年   44篇
  1992年   46篇
  1991年   36篇
  1990年   38篇
  1989年   27篇
  1988年   31篇
  1987年   31篇
  1986年   22篇
  1985年   70篇
  1984年   60篇
  1982年   28篇
  1981年   29篇
  1980年   23篇
  1979年   36篇
  1978年   28篇
  1977年   28篇
  1976年   18篇
  1975年   18篇
  1974年   20篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
OBJECTIVES: To evaluate fine motor (FM) and gross motor (GM) function shortly after school entry in children with a preschool diagnosis of developmental language impairment (DLI). STUDY DESIGN: A cohort of children (n = 70) diagnosed at pre-school age with DLI was reevaluated in elementary school. Language, cognitive, and motor outcomes were assessed through the use of the Battelle Developmental Inventory (BDI). Language was further assessed through the use of the Vineland Adaptive Behavior Scale, Peabody Picture Vocabulary, and Expressive One Word Picture Vocabulary Tests. Performance below -1.5 SD of the normative mean on any test was considered to represent impairment. RESULTS: Forty-three children (mean age, 7.4 +/- 0.7 years) underwent reassessment at a mean of 3.8 +/- 0.7 years after initial preschool assessment. Mean scores for BDI motor domains (FM, 78.3 +/- 11.4; GM, 84.9 +/- 13.3) fell below normative values. Twenty-two children (52%) had motor impairment (FM, 17 of 42; GM, 15 of 42); 35 of 43 (81%) continued to have language impairment. BDI communication raw scores correlated most strongly with FM (rho = 0.73, P < .001) and GM (rho = 0.58, P = .003) raw scores but showed only moderate correlations with cognitive raw scores (rho = 0.41, P = .05). CONCLUSIONS: Impaired motor function is an important comorbidity in DLI. Factors critical to motor performance may also contribute to language deficits in DLI.  相似文献   
992.
In the present study, we have investigated the effects and interaction of CCK and GABAergic systems in the dorsal hippocampus of rats using the elevated plus-maze test of anxiety. Bilateral injection of different doses of CCK(8s) (0.01, 0.05 and 0.1 microg/rat) into the dorsal hippocampus (intra-CA1) decreased percentage of open arm time (%OAT) and open arm entries (%OAE) that are representative of anxiogenic-like behavior. The bilateral injection of three doses of LY225910, a selective CCK2 receptor antagonist (0.01, 0.1 and 0.5 microg/rat) produced significant anxiolytic behavior. Although muscimol (GABA(A+)) (0.1, 0.5 and 1 microg/rat, intra-CA1) produced dose dependent increase in %OAT and a slight increase in %OAE, bicuculline (GABA(A-)), (1, 2 and 4 microg/rat, intra-CA1) failed to change the anxiety profile. Both muscimol (0.1 microg/rat) and bicuculline (1 microg/rat), when co-administered with LY225910, reversed the effect of latter drug on anxiety but when co-administered with CCK8s (0.05 microg/rat) showed no effect on anxiety profile. In conclusion, it seems that both CCK and GABAergic systems not only play a part in the modulation of anxiety in the dorsal hippocampus of rats but also have demonstrated a complex interaction as well.  相似文献   
993.
Evidence from event-related potential (ERP) studies indicates abnormal error processing and attentional allocation in "trait"-anxious individuals. However, few studies have been conducted that evaluate relevant ERP components during the induction of an anxious state (i.e., fear). In the present study, ERPs were measured in 16 undergraduates during control and fear induction conditions to examine the effects of fear on error processing and attentional allocation. Despite comparable performance in both experimental conditions, the ERP data indicated reductions in attentional allocation and error salience during fear induction. Fear did not appear to directly alter early error processing, as indicated by the error-related negativity, however. The implication of these results for understanding how trait and state anxiety may affect error processing and attentional allocation are discussed.  相似文献   
994.
The aim of the present study was to investigate the role of EEG mapping as an objective and quantitative measure of vigilance in untreated and modafinil–treated narcoleptics, and compare it with the conventional neurophysiological method of the Multiple Sleep Latency Test (MSLT) and the subjective Epworth Sleepiness Scale (ESS). In 16 drug–free narcoleptics and 16 normal controls a baseline 3–min vigilance–controlled EEG (V–EEG) and a 4–min resting EEG (R–EEG) were recorded during midmorning hours. Thereafter, in a double–blind, placebo–controlled crossover design, patients were treated with a 3–week fixed titration of modafinil (200, 300, 400 mg) and placebo. EEG–mapping, MSLT and ESS measures were obtained before and at the end of the third week of therapy. Statistical overall analysis by means of the omnibus significance test demonstrated significant EEG differences between untreated patients and controls in the resting condition only (R–EEG). Subsequent univariate analysis revealed an increase in absolute and relative theta power, a decrease in alpha–2 and beta power as well as a slowing of the dominant frequency and the centroids of the alpha, beta and total power spectrum and thus objectified a vigilance decrement in narcolepsy. Modafinil 400 mg/d significantly improved vigilance as compared with placebo (p 0.01), inducing changes opposite to the aforementioned baseline differences (key–lock principle). The MSLT and the ESS also improved under modafinil as compared with placebo, but changes were less consistent. Spearman rank correlations revealed the highest correlations between EEG mapping and the ESS, followed by those between EEG mapping and the MSLT, while the lowest correlation was found between the MSLT and the ESS. In conclusion, EEG mapping is a valuable instrument for measuring vigilance decrements in narcolepsy and their improvement under psychostimulant treatment.  相似文献   
995.
The present study was conducted to investigate the difference in the characteristics of daytime sleepiness between narcolepsy and essential hypersomnia and to identify the relationship between the Epworth Sleepiness Scale (ESS) and the Multiple Sleep Latency Test (MSLT) in patients with these two disorders. Subjects consisted of 34 patients with essential hypersomnia (32.4 +/- 11.0 years old), 52 patients with narcolepsy (29.0 +/- 13.8 years old), and 45 control subjects (33.3 +/- 6.6 years old). The subjects completed the ESS and underwent MSLT following a regular sleep-wake schedule for over 2 weeks. The ESS scores were pathologically high and mean sleep latency on MSLT was short, not only in narcolepsy but also in essential hypersomnia. With respect to sleep latencies on each MSLT session, both essential hypersomnia and control subjects had the smallest value at 14:00, while narcolepsy lacked any statistical change at this time period. The correlation between ESS and mean sleep latency on MSLT was higher in essential hypersomnia than in narcolepsy, and the correlation was strongest for the session performed at 14:00. Based on the ESS and MSLT results, the severity of excessive daytime sleepiness was significantly milder in essential hypersomnia compared with that in narcolepsy. The results also indicate that diurnal variation of sleepiness was maintained, and the correlation between subjective and objective sleepiness was relatively maintained in essential hypersomnia compared to narcolepsy. It is suggested that the mild disease severity of essential hypersomnia contributed to the formation of these characteristics.  相似文献   
996.
Anxiety and depression of patients with digestive cancer   总被引:5,自引:0,他引:5  
This study sought to characterize the psychological status of digestive cancer patients, and to investigate the relationship between psychological characteristics and clinical factors. Subjects were 85 inpatients scheduled to undergo surgery for digestive cancer and 26 control patients. The Japanese versions of Hospital Anxiety and Depression Scale (HADS) and Zung's Self Rating Depression Scale (SDS) were administered for all subjects before surgery, before discharge, and 6 months after discharge. Changes in HADS and SDS scores across the three examination days for three groups of subjects (advanced-phase, early phase, and control groups) were compared. The mean scores of anxiety and depression were significantly higher in the advanced-phase group than in the other two groups. Examination day showed a significant effect on depression; depression increased from before surgery to before discharge, and did not return to the preoperative level at 6 months after discharge, but no significant effect on anxiety. As for the relationship between psychological trends and clinical factors, anxiety in the 'middle age' and 'chemotherapy' groups was more severe than in the 'elderly' and 'no chemotherapy' groups. Depression in the 'medical treatment equipment', 'chemotherapy', and 'long-term hospitalization' groups was more severe than in the 'no equipment', 'no chemotherapy', and 'standard-term hospitalization' groups. These results suggest that we should pay careful attention to cancer patients undergoing surgery, especially young patients who are constantly at risk of anxiety, and assess their depression taking into account their disease and treatment conditions, especially after the time when their discharge is determined.  相似文献   
997.
Obsessive-compulsive symptoms (OCS) have been observed in a substantial proportion of schizophrenic patients. In this study, the rate of occurrence of OCS and obsessive-compulsive disorder (OCD) in schizophrenic patients, and also the interrelationship between OCS and schizophrenic symptoms and depressive symptoms were assessed. A total of 100 subjects with a diagnosis of schizophrenia from the 4th edition of the Diagnostic and Statistical Manual (DSM-IV) were evaluated by the structured and clinical interview for axis-1 DSM-IV disorders-patient edition (SCID-P), the Positive and Negative Syndrome Scale (PANSS), Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), and the Calgary Depression Rating Scale for Schizophrenia. The prevalance of OCS in individuals meeting criteria for schizophrenia was 64%. A total of 30 of these patients (Y-BOCS total score > or =7) also met the DSM-IV criteria for OCD. The total score on Y-BOCS was significantly correlated with total score on PANSS, Positive-PANSS score, General-PANSS score and total score on Calgary Depression Rating Scale for Schizophrenia. OCS and OCD relatively frequent in schizophrenic patients and OCS are significantly correlated with the severity of psychosis, positive symptoms, and depressive symptoms in schizophrenic patients. These findings provide further evidence for the importance of OCS in schizophrenia.  相似文献   
998.
BACKGROUND AND AIMS: Hepatitis C virus (HCV) diagnosis causes significant psychological stress and anxiety. We thought it would be important to illustrate the anxiety caused by HCV diagnosis in patients from the developing world. METHODS: This study was conducted at the Shifa International Hospital, Islamabad, between February 2004 and April 2004. All patients who were recently diagnosed with HCV (those who tested positive to anti-HCV and HCV polymerase chain reaction) were given a questionnaire that compared stress due to HCV infection with four other variables, including death of a close family member, divorce, loss of source of income and move to another city. We also analyzed the anxiety level among these patients using the Beck Anxiety Inventory (BAI). RESULTS: We studied 98 patients and 100 healthy controls. Thirty-one (31.63%) patients who were diagnosed with HCV presented only with fatigue. Sixty-three (64.28%) patients admitted that diagnosis of HCV interfered with their daily life in some way. Among the newly diagnosed cases, 48 (48.97%) patients had moderate to severe anxiety (BAI Class B and C). Multi-logistic regression analysis showed that anxiety was related to HCV-related stress (P < 0.002) and self-perceived severity of disease (P < 0.001). HCV diagnosis was significantly more stressful than divorce (59.87 vs 70.95; P < 0.013), loss of source of income (50.52 vs 70.80; P < 0.001), and a move to another city (28.32 vs 70.80; P < 0.001). CONCLUSIONS: Diagnosis with HCV is reported to be more stressful than divorce, loss of source of income and a move to another city.  相似文献   
999.
OBJECTIVE: This study aims to investigate if a brief version (four items) of the Geriatric Depression Scale works equally well with mildly demented as with nondemented patients in young-old and old-old persons, and to compare its diagnostic performances with those of the 15- and the 30-item version of the scale. METHOD: Four hundred and forty-two older persons were given a GDS interview and received an independent psychiatric evaluation. Receiver operating characteristic curves were separately plotted for the young-old demented, old-old demented, young-old nondemented, and old-old nondemented. RESULTS: The four-item version yielded comparable performance to the 15- and the 30-item version of the GDS, regardless of age and dementia status. It is reasonably robust to the effects of age and mild dementia, whether alone or in combination. Nonetheless, among the old-old demented, only a third of those tested positive were actually positive, but this problem was not specific to the four-item version. CONCLUSIONS: The four-item version can be used in lieu of the longer versions to conserve clinical and research resources where appropriate, and a cutoff of 1/2 can be applied across the board. Little, if any, information is lost when this brief version is used instead of the longer ones.  相似文献   
1000.
The factor structure of the SF-36 in early pregnancy   总被引:1,自引:0,他引:1  
OBJECTIVE: The concept of Quality of Life (QoL) has emerged as an important psychological dimension within pregnancy. The current study sought to establish the psychometric properties of the Medical Outcomes Study Short Form 36 (SF-36) Version 2 in early pregnancy to evaluate the clinical appropriateness of using this measure with women in early pregnancy. METHODS: Exploratory and confirmatory factor analyses were conducted on self-report SF-36 data from 129 women during early pregnancy. Measures of anxiety and depression were also administered to determine the impact of psychiatric case classification on SF-36 subscale scores in this clinical group. RESULTS: The underlying factor structure of the SF-36 comprised a general third-order superordinate domain of health and two second-order factors of physical health and mental health. The SF-36 subscales were observed to be sensitive to the affective status of participants. CONCLUSION: The use of the SF-36 in early pregnancy as a clinical research tool comprising eight subscales is recommended. The relative merits of scoring the instrument as a two-subscale measure of physical health and mental health require further evaluation.  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