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   1533篇
  免费   178篇
  国内免费   28篇
耳鼻咽喉   6篇
儿科学   150篇
妇产科学   27篇
基础医学   201篇
口腔科学   90篇
临床医学   157篇
内科学   284篇
皮肤病学   50篇
神经病学   46篇
特种医学   173篇
外科学   234篇
综合类   38篇
预防医学   95篇
眼科学   40篇
药学   53篇
中国医学   2篇
肿瘤学   93篇
  2023年   14篇
  2022年   10篇
  2021年   13篇
  2020年   14篇
  2019年   7篇
  2018年   44篇
  2017年   46篇
  2016年   41篇
  2015年   60篇
  2014年   76篇
  2013年   107篇
  2012年   46篇
  2011年   29篇
  2010年   78篇
  2009年   91篇
  2008年   28篇
  2007年   48篇
  2006年   48篇
  2005年   25篇
  2004年   28篇
  2003年   13篇
  2002年   19篇
  2001年   15篇
  2000年   9篇
  1999年   24篇
  1998年   101篇
  1997年   86篇
  1996年   99篇
  1995年   64篇
  1994年   74篇
  1993年   39篇
  1992年   14篇
  1991年   21篇
  1990年   13篇
  1989年   31篇
  1988年   29篇
  1987年   28篇
  1986年   26篇
  1985年   24篇
  1984年   12篇
  1983年   9篇
  1982年   20篇
  1981年   15篇
  1980年   16篇
  1977年   9篇
  1976年   13篇
  1975年   9篇
  1956年   8篇
  1955年   6篇
  1954年   7篇
排序方式: 共有1739条查询结果,搜索用时 156 毫秒
371.
372.
Herpes simplex virus type 1 and type 2 cause a wide range of illnesses ranging from minor cold sores to severe necrotising encephalitis or disseminated systemic infections seen in immunocompromised patients including neonates. Following primary infection, the virus is not eradicated from the body but is latent in sensory nerve ganglia where it can reactivate and cause recurrent disease. Aciclovir is the most studied and used antiviral agent with activity against herpes simplex virus infections. In most situations the use of aciclovir shortens the duration of clinical illness and viral shedding and reduces morbidity and mortality. All life- or sight-threatening infections should be managed in an inpatient hospital setting with intravenous therapy. The use of oral aciclovir is recommended in patients with non-life-threatening illness who may still have significant symptoms.  相似文献   
373.
Children with the long QT syndrome (LQTS) are prone to life threatening ventricular arrhythmias. These arrhythmias may result in syncope and seizures that are often attributed incorrectly to a seizure disorder or to common fainting. The untreated mortality for symptomatic children with the LQTS is high but is improved significantly with therapy. Paediatricians should be aware of the presentations of the syndrome. Recommendations for screening for the syndrome are given.  相似文献   
374.
Cerebral fractional oxygen extraction (FOE) was monitored in 30 children, using near infrared spectroscopy during cardiopulmonary bypass, to investigate the effect of hypothermia and circulatory arrest. One group of children (n = 15) underwent profound hypothermia with total circulatory arrest (n = 8) or continuous flow (n = 7). Another group (n = 15), of whom only one had circulatory arrest, underwent mild (n = 6) or moderate (n = 9) hypothermia. The mean FOE (SD) before bypass was 0.35 (0.12) and this correlated negatively with the preoperative arterial oxygen content (r = -0.58). Between the stage of cooling on bypass and cold bypass there was a reduction in FOE in all groups. Between cold bypass and rewarming there was an increase in FOE only in the groups with continuous flow. In the circulatory arrest group, the FOE remained low during rewarming and was significantly lower than that of the continuous flow group. No patients died and none had neurological abnormalities postoperatively. Apparent changes in oxidised cytochrome oxidase concentration were also monitored using near infrared spectroscopy. There was a fall in cytochrome aa3 on starting cardiopulmonary bypass, but there were no significant differences in the changes in cytochrome aa3 between any stage in any of the patient groups. Using this non-invasive technique, cooling was shown to reduce cerebral FOE. During rewarming on bypass there was an increase in cerebral FOE only in patients who had had continuous flow bypass. In contrast, the cerebral FOE in those with circulatory arrest remained constant after arrest and during the duration of the study. This may have implications for the timing of hypoxic brain injury.  相似文献   
375.
OBJECTIVES: Estimate pregnancy, abortion, and birth rates for 1990 to 1995 for all teens, sexually experienced teens, and sexually active teens. DESISN: Retrospective analysis of national data on pregnancies, abortions, and births. Participants. US women aged 15 to 19 years. OUTCOME MEASURES: Annual pregnancy, abortion, and birth rates for 1990 to 1995 for women aged 15 to 19 years, with and without adjustments for sexual experience (ever had intercourse), and sexual activity (had intercourse within last 3 months). RESULTS: Approximately 40% of women aged 15 to 19 years were sexually active in 1995. Teen pregnancy rates were constant from 1990 to 1991. From 1991 to 1995, the annual pregnancy rate for women aged 15 to 19 years decreased by 13% to 83.6 per 1000. The percentage of teen pregnancies that ended in induced abortions decreased yearly; thus, the abortion rate decreased more than the birth rate (21% vs 9%). From 1988 to 1995, the proportion of sexually experienced teens decreased nonsignificantly. CONCLUSIONS: After a 9% rise from 1985 to 1990, teen pregnancy rates reached a turning point in 1991 and are now declining. Physicians should counsel their adolescent patients about responsible sexual behavior, including abstinence and proper use of regular and emergency contraception.  相似文献   
376.
Correction for gestational age continues to make a difference to the height SD score (SDS) to the age of seven years in very preterm babies. The height SDS for children born at 28 weeks' gestation increased by 0.25 SDS when postconceptual age was used instead of real age. Extrapolating from these results, the effect of correction would be an increase of approximately 0.32 SDS for a seven-year-old of 24 weeks' gestation. Unsatisfactory growth may be masked by a steady or increasing real age SDS in a few children. The risks of stopping using postconceptual age at two or three years include both false confidence in genuine cases of growth retardation and misinterpretation of a decrease in height SDS as evidence of growth retardation. As the number of very preterm babies who survive increases so does the importance of these observations.  相似文献   
377.
We performed a randomized study of hydroxyurea (HY) versus VP16 in advanced chronic myelomonocytic leukemia (CMML) patients with CMML (according to French-American-British group criteria) and either documented visceral involvement (excluding liver and spleen infiltration) or at least 2 of the following: (1) neutrophils > 16 x 10(9)/I (2) Hemoglobin < 10 g/dL (3) platelets < 100 x 10(9)/L (4) marrow blasts > 5% (5) spleen > 5 cm below costal margin were eligible for this trial. Initial dosage was 1 g/d for HY and 150 mg/week for VP16, orally (doubled in case of visceral involvement). Doses were scheduled to be escalated up to HY 4 g/d and VP16 600 mg/week in the absence of response, and finally adjusted to maintain white blood cells (WBCs) between 5 and 10 x 10(9)/L. Crossing over was scheduled only in case of life threatening visceral involvement or major progression. The major endpoint of the study was survival. The study was closed on first interim analysis that showed a superiority of HY over VP16, after inclusion of 105 pts (HY arm: 53, VP16 arm: 52). Results of the second interim analysis, performed 7 months later, are presented here. Median age was 71 (range 38 to 91), median WBC count 20.10(9)/L (range 10 to 187). Thirteen pts had visceral involvement (3 serous effusions, 8 cutaneous infiltrations, 1 kidney, 1 bone infiltrations). Initial characteristics were similar in the HY and VP16 groups. Median follow up was 11 months in both groups (range 1 to 43+). Response to treatment was seen in 60% of the pts in the HY group, versus 36%, respectively, in the VP16 group (P = .02). Time to response was significantly shorter in the HY group (2.1 v 3.5 months, in the VP16 group, P = .003) and response duration was significantly longer in the HY group (median 24 v 9 months, in the VP16 group, P = .0004). The response rate of patients with visceral involvement was 3 out of 7 in the VP16 arm versus 5 out of 6 in the HY group. Three of the 10 pts crossed over from HY to VP16 responded as compared to 6 pts of the 11 pts crossed over from VP16 to HY. HY yielded better response on leukocytosis (P = .002). The effect on splenomegaly platelets, on hemoglobin level and transfusion requirement was similar in the 2 treatment groups. A significantly higher incidence of alopecia was noted in the VP16 arm (20% v 3%, P = .03). Fourteen (27%) and 20 (38%) patients in the HY and the VP16 group respectively, progressed to acute myeloid leukemia (difference NS). Twenty five (53%) and 44 (83%) patients in the HY and the VP16 group, respectively, had died (P = .002). Median actuarial survival was 20 months in the HY arm, versus 9 months in the VP16 arm (P < 10(-4)). Main factors associated with poor survival were allocation to the VP16 arm, "unfavorable" karyotype (ie, monosomy 7 or complex abnormalities) and anemia. In the HY group, unfavorable karyotype (P = .006), and low hemoglobin level (P = .004) were significantly associated with low response rates. Prognostic factors for poor survival in the HY group were also unfavorable karyotype (P = .001), and low hemoglobin level (P < 10(-4). In conclusion, we found that HY gave higher response rates and better survival than VP16 in advanced CMML. However, even with HY responses were only partial and survival was generally poor. This stresses the need for new agents in the treatment of CMML, that will have to be compared with HY in future randomized studies.  相似文献   
378.
379.
380.
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