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   325800篇
  免费   29197篇
  国内免费   22938篇
耳鼻咽喉   2998篇
儿科学   3454篇
妇产科学   4952篇
基础医学   40126篇
口腔科学   5525篇
临床医学   45425篇
内科学   49987篇
皮肤病学   3101篇
神经病学   18413篇
特种医学   12036篇
外国民族医学   213篇
外科学   33417篇
综合类   50079篇
现状与发展   76篇
一般理论   23篇
预防医学   19784篇
眼科学   9598篇
药学   32910篇
  334篇
中国医学   17481篇
肿瘤学   28003篇
  2024年   1002篇
  2023年   5029篇
  2022年   13077篇
  2021年   16447篇
  2020年   12068篇
  2019年   10937篇
  2018年   11443篇
  2017年   9942篇
  2016年   9377篇
  2015年   14379篇
  2014年   17838篇
  2013年   15393篇
  2012年   22883篇
  2011年   25886篇
  2010年   15959篇
  2009年   12290篇
  2008年   17074篇
  2007年   17081篇
  2006年   17147篇
  2005年   16849篇
  2004年   10782篇
  2003年   9911篇
  2002年   8566篇
  2001年   7567篇
  2000年   8339篇
  1999年   9053篇
  1998年   5498篇
  1997年   5524篇
  1996年   4347篇
  1995年   3936篇
  1994年   3224篇
  1993年   2104篇
  1992年   2839篇
  1991年   2430篇
  1990年   2128篇
  1989年   1878篇
  1988年   1568篇
  1987年   1358篇
  1986年   1114篇
  1985年   918篇
  1984年   533篇
  1983年   379篇
  1982年   246篇
  1981年   241篇
  1980年   191篇
  1979年   222篇
  1978年   87篇
  1977年   93篇
  1974年   105篇
  1973年   90篇
排序方式: 共有10000条查询结果,搜索用时 6 毫秒
991.
We compared analgesia to the T4 dermatomal level with analgesia to the T7 level with and without prophylactic intramuscular administration of ephedrine 25 mg to determine the adequacy and side effects of such analgesia for caesarean section. Unmedicated patients were prehydrated (727 ± 303 ml of saline solution) and kept in a left lateral tilt position. Sufficient three per cent chloroprocaine was given to obtain analgesia to the T7 (T6-T8) dermatomal level (455 ± 128 mg) or to the T4 (T3-T5) dermatomal level (758 ± 168 mg). Patients who received analgesia to the higher level required less narcotic than those who received analgesia to the lower level (21 per cent versus 48 per cent) (p < 0.05). The incidence of hypotension in patients with analgesia at the T4 level was 21 per cent for those receiving ephedrine and 64 per cent for those who did not receive ephedrine (p < 0.05). Intramuscular administration of ephedrine 25 mg was not associated with increased plasma levels of norepinephrine, epinephrine or dopamine. There was no difference in Apgar score, behavioural test scores, neonatal acid-base status or oxygenation in children of mothers in the different groups. We conclude that a T4 dermatomal level of analgesia, combined with intramuscular administration of ephedrine 25 mg, provides more maternal comfort than a T7 level of analgesia does, with or without ephedrine, and is without significant maternal or foetal side effects.  相似文献   
992.
本文从中药黄藤的根及根茎中分得三种季铵生物碱,化学及光谱数据证明,一为掌叶防己碱(巴马汀),二为药根碱,三系伪非洲防己胺碱。后者为国内首次得到的一种天然伪原小檗碱型生物碱。  相似文献   
993.
994.
OBJECTIVE: This study longitudinally described rates of posttraumatic stress disorder (PTSD) in two groups with different levels of severity of exposure to an earthquake in North China. The effects of diagnostic criteria on the frequency of detected PTSD were also examined. METHOD: Subjects were randomly sampled in two villages at different distances from the earthquake epicenter. A total of 181 and 157 subjects were assessed at 3 months and 9 months after the earthquake, respectively, for PTSD by using both DSM-IV and DSM-III-R criteria. The brief version of the World Health Organization Quality of Life Assessment and three subscales of the SCL-90-R were also administered at both assessment points. RESULTS: The village with a higher level of initial exposure to the earthquake and a higher level of postearthquake support had a lower frequency of PTSD than the village with a lower level of initial exposure and less postearthquake support. The rate of onset of DSM-IV PTSD within 9 months for the two villages was 19.8% and 30.3%, respectively. In both villages, the rate of onset of earthquake-related PTSD within 9 months was 24.2% by using DSM-IV criteria and 41.4% by using DSM-III-R criteria. The introduction in DSM-IV of a criterion requiring clinically significant distress or impairment in functioning for a diagnosis of PTSD was a major contributor to the lower rate of DSM-IV PTSD. CONCLUSIONS: PTSD may be as prevalent and persistent in disaster victims in China as in those elsewhere. Prompt and effective postdisaster intervention could mitigate the impact of initial exposure and reduce the probability of PTSD occurrence. Caution should be used in comparing rates of postdisaster PTSD identified by using different diagnostic criteria.  相似文献   
995.
996.
Objective: The symptoms of depression experienced by women during the postnatal period may have profound effects on the lifelong health of both the mother and the child. In this randomized controlled study, we systematically evaluated the effects of weekly supportive group meetings for women with postnatal distress. Methods: Sixty postnatally distressed women were randomly assigned to support (n=30) and control (n=30) groups. Women assigned to the support group participated in four supportive group sessions that comprised discussions concerning transition to motherhood, postnatal stress management, communication skills, and life planning. Results: Subjects who attended the support sessions had significantly decreased scores on the Beck Depression Inventory (BDI) and the Perceived Stress Scale (PSS), and significantly increased scores on the Interpersonal Support Evaluation List (ISEL) as evaluated at the end of the fourth weekly session. In contrast, no significant changes were observed in the control group during this period. Conclusion: This is the first controlled study to provide evidence that participation in support groups for postnatally distressed women provides quantifiable psychosocial benefits.  相似文献   
997.
BACKGROUND AND PURPOSE: Since the FDA approved tissue plasminogen activator (tPA) in 1996 for acute ischemic stroke, few data have been obtained during the postmarketing phase, and applicability in rural hospitals does not exist. We attempt to examine the safety and outcome of intravenous tPA for acute ischemic stroke in the OSF Stroke Network. METHODS: Fifty-seven consecutive patients treated with tPA were examined from June 1996 through December 1998. Admission and discharge National Institute of Health Stroke Scales (NIHSS), modified Rankin Scales (MRS), and discharge disposition, as well as intracerebral hemorrhage and mortality rates, were compared. RESULTS: Of 20 network hospitals, 12 had the experience of administering tPA. No statistically significant differences in the variables recorded were observed for patients treated at the community hospitals versus those who received tPA at the tertiary medical center. In 35% of patients, tPA was initiated by an emergency room or primary care physician in consultation with an OSF neurologist. At discharge, 47% of the patients had minimal or no disability (MRS, 0 to 1), 44% had an NIHSS score of 0 or 1, 54% went home, 25% were transferred to in-patient rehabilitation, 12% went to a nursing or skilled-care facility, and 9% died. Intracerebral hemorrhage rate was 9%; 5% were symptomatic. CONCLUSIONS: tPA can be administered safely with good outcome at community and rural hospitals. The OSF Stroke Network can serve as a model to assist small community hospitals to set up stroke programs and deliver up-to-date, acute stroke therapies.  相似文献   
998.
999.
Researchers from Japan, China and Singapore have initiated a collaborative project, with the aim of comparing adolescent quality of life (QOL) internationally. This study presents the primary results of the investigation conducted in Beijing, China, and Kobe, Japan. The 70-item Quality of Life Questionnaire for Adolescents (QOLQA) was developed and evaluated in Japan and China. In total, 1114 Japanese and 613 Chinese junior high school students, aged 12-15 years, completed the questionnaire. Chinese students scored significantly higher than the Japanese students in overall QOL scores and in most domains. For both groups, subjects had highest score in the independence domain and lowest in psychological domain. In terms of overall QOL score, Chinese male students ranked first, followed by Chinese girls, Japanese boys, and Japanese girls. In the Japanese group, a continuing decrease of QOL scores with age was observed without exception, but no such tendency was present in their Chinese counterparts. No parallel relationship was observed between the higher level of economic development and better quality of life. The results also suggest that mental health promotion should be a priority in improving overall quality of life of adolescents both in Japan and China.  相似文献   
1000.
Liu HM  Huang YC  Wang YH  Tu YK 《Neuroradiology》2000,42(10):766-770
We report the effectiveness of low-concentration n-butyl-2-cyanoacrylate (NBCA)-Lipiodol-tungsten mixture (10–15 %) in the management of patients with aggressive or recurrent complex cavernous dural arteriovenous fistulae (CSDAVF). We treated five patients with complex CSDAVF with a low concentration of an NBCA-Lipiodol-tungsten mixture after catheterisation of the feeding arteries arising from the external carotid artery. Three had a recurrent CSDAVF after transarterial particulate embolisation. Three refused transvenous treatment or could not be treated in this way; two patients had also feeding dural branches of the internal carotid artery. All patients had complete resolution of symptoms and signs within a month of the procedure. No definite neurological complication was found during follow-up ranging from 12 to 36 months. Transarterial embolisation with low-concentration cyanoacrylate appears to be an effective alternative management of aggressive or recurrent CSDAVF. Received: 8 November 1999/Accepted: 2 March 2000  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