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   2222054篇
  免费   167861篇
  国内免费   26570篇
耳鼻咽喉   27517篇
儿科学   65582篇
妇产科学   51478篇
基础医学   283367篇
口腔科学   60028篇
临床医学   206368篇
内科学   393907篇
皮肤病学   46600篇
神经病学   149136篇
特种医学   82476篇
外国民族医学   243篇
外科学   304959篇
综合类   152977篇
现状与发展   97篇
一般理论   553篇
预防医学   187751篇
眼科学   48456篇
药学   183829篇
  663篇
中国医学   47152篇
肿瘤学   123346篇
  2022年   18526篇
  2021年   30913篇
  2020年   23604篇
  2019年   23108篇
  2018年   31652篇
  2017年   28890篇
  2016年   27387篇
  2015年   37341篇
  2014年   49328篇
  2013年   68242篇
  2012年   97743篇
  2011年   103482篇
  2010年   72809篇
  2009年   65116篇
  2008年   90591篇
  2007年   93120篇
  2006年   89509篇
  2005年   80522篇
  2004年   71986篇
  2003年   66055篇
  2002年   61123篇
  2001年   103515篇
  2000年   103697篇
  1999年   82090篇
  1998年   20746篇
  1997年   17988篇
  1996年   18086篇
  1995年   17351篇
  1994年   15864篇
  1993年   14453篇
  1992年   59231篇
  1991年   56925篇
  1990年   54599篇
  1989年   52154篇
  1988年   47485篇
  1987年   46256篇
  1986年   43591篇
  1985年   41251篇
  1984年   30228篇
  1983年   25698篇
  1982年   14343篇
  1979年   26573篇
  1978年   18256篇
  1977年   15569篇
  1976年   14495篇
  1975年   15313篇
  1974年   18607篇
  1973年   17935篇
  1972年   16637篇
  1971年   15400篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
目的 用患者样本分析葡萄糖氧化酶-氧电极法(简称电极法)和己糖激酶(HK)法测定血清葡萄糖(GLU)时的偏倚。方法 依据美国临床实验室标准化委员舍(NCCLS)EP9—A文件,每天取患者样本8份,分别用两种方法测定血清葡萄糖含量,共测定5d,记录检验结果,去除离群点,计算线性方程和相关系数,并进行偏倚估计。结果 在进行患者葡萄糖测定时,电极法(Y)和HK法(X)测定结果的回归方程为:Y=0.9857X 0.08967,r^2=0.9992;电极法和HK法测定结果的预期相对偏倚在GLU=15mmo1/L时为0.80%,GLU=9mmo1/L时为0.44%,GLU=6mmo1/L时为0.00%,GLU=3mmo1/L时为1.67%。结论 电极法和HK法测定血清葡萄糖时,测定结果在低浓度时偏倚较大,在中、高浓度时偏倚较小,两法间有良好的相关性。  相似文献   
92.
93.
We previously reported poorer survival among non-Hispanic blacks and Hispanics with idiopathic pulmonary fibrosis (IPF) compared to non-Hispanic whites at our center. In the current study, we hypothesized that these disparities would exist in a nationwide cohort of wait-listed patients with IPF. We performed a retrospective cohort study of 2635 patients with IPF listed for lung transplantation between 1995 and 2003 at 94 transplant centers in the United States. The age-adjusted mortality rate was higher among non-Hispanic blacks [hazard ratio (HR) = 1.24, 95% confidence interval (CI) 1.06-1.45, p = 0.009] and Hispanics (HR = 1.29, 95% CI 1.06-1.56, p = 0.01) compared to non-Hispanic whites. These findings persisted after adjustment for transplantation, medical comorbidities and socioeconomic status. Worse lung function at the time of listing appeared to explain some of these differences (HR for non-Hispanic blacks after adjustment for forced vital capacity percent predicted = 1.16, 95% CI 0.98-1.36, p = 0.09; HR for Hispanics = 1.21, 95% CI 0.99-1.48, p = 0.056). In summary, black and Hispanic patients with IPF have worse survival than whites after listing for lung transplant.  相似文献   
94.
目的:窦道是通达组织深部的盲管性创道,时发时愈,迁延日久.是临床工作者常见的问题,治疗十分困难;为探索窦道的新的治疗途径,开展了微波治疗窦道的临床研究.方法:微波组:采用微波热机局部照射 外科常规换药治疗;根据病变部位分别选择直径为10cm或16cm的辐射器,辐射器距窦道口距离为3cm~5cm,隔1d或隔2d治疗1次,每次30 min,10次为1个疗程,微波治疗功率为70W,治疗结束观察治疗效果.对照组:按外科常规换药治疗.结果:微波组痊愈率98%,好转率2%,总有效率100%;对照组痊愈率37.5%,有效率37.5%,无效率25%,总有效率75%;结论:微波治疗窦道不愈患者具有简单、安全、方便、疗效独特等优点.  相似文献   
95.
We describe the simple adaptation of a standard fluorescent microscope for illumination using a 'Royal Blue' Luxeon light emitting diode (LED) and demonstrate that this form of illumination is suitable for the detection of auramine O stained Mycobacterium spp. The low cost, low power consumption, safety and reliability of LEDs makes them attractive alternatives to mercury vapour lamps.  相似文献   
96.
97.
98.
CONTEXT: Although the nonmedical use of stimulant drugs such as cocaine and methamphetamine is increasingly common in many rural areas of the United States, little is known about the health beliefs of people who use these drugs. PURPOSE: This research describes illicit stimulant drug users' views on health and health-related concepts that may affect their utilization of health care services. METHODS: A respondent-driven sampling plan was used to recruit 249 not-in-treatment, nonmedical stimulant drug users who were residing in 3 rural counties in west central Ohio. A structured questionnaire administered by trained interviewers was used to collect information on a range of topics, including current drug use, self-reported health status, perceived need for substance abuse treatment, and beliefs about health and health services. FINDINGS: Participants reported using a wide variety of drugs nonmedically, some by injection. Alcohol and marijuana were the most commonly used drugs in the 30 days prior to the interview. Powder cocaine was used by 72.3% of the sample, crack by 68.3%, and methamphetamine by 29.7%. Fair or poor health status was reported by 41.3% of the participants. Only 20.9% of the sample felt they needed drug abuse treatment. Less than one third of the sample reported that they would feel comfortable talking to a physician about their drug use, and 65.1% said they preferred taking care of their problems without getting professional help. CONCLUSIONS: Stimulant drug users in rural Ohio are involved with a range of substances and hold health beliefs that may impede health services utilization.  相似文献   
99.
PURPOSE: In children with locally advanced or recurrent malignant tumours, prognosis can be improved by regional deep hyperthermia (RHT) in combination with platin-based chemotherapy. However, because of the increasing number of patients that achieve long-time remission with this therapy, it is necessary to evaluate long-term sequelae of thermochemotherapy. During the years 1993-2004 one has observed avascular osteonecrosis (AON) of the femoral head after RHT in seven children with pelvic germ cell tumours or rhabdomyosarcomas. METHODS: Although AON may develop in patients with malignancies treated with chemo- or radiotherapy alone, RHT might nevertheless contribute to the occurrence of AON. In order to determine potential risk factors for AON after RHT, this study analysed the relationship of AON to the patient's age, medical history and treatment parameters such as thermal dose equivalent and power output. RESULTS AND CONCLUSIONS: In the present study AON was associated with young age as well as intensity of hyperthermia indicated by high power levels that exceed 20 W per kg body weight and/or application of eight or more heat sessions as well as additional radiotherapy. Based on this observation, it was assumed that an optimized three dimensional thermal field modelling may be helpful to avoid hazardous temperatures in the femoral heads during RHT treatment and to reduce AON of the femoral heads.  相似文献   
100.
OBJECTIVE: To assess the effect of glucose control on the rate of growth of fetuses in women with pregestational diabetes mellitus (Types 1 and 2). METHODS: All pregestational diabetic women booked at Mater Mothers' Hospital, Brisbane, Australia, between 1 January 1994 and 31 December 2002, were included. Pregnancies with congenital fetal anomalies, multiple pregnancies, and pregnancies terminated prior to 20 weeks' gestation were excluded. Dating scans were performed before 14 weeks' gestation and serial scans were performed at 18, 24, 28, 32 and 36 weeks. Fetal parameters, including biparietal diameter, femur length and abdominal circumference, were recorded. The daily growth rates for biparietal diameter, femur length, and fetal abdominal area were calculated and compared with those in a low-risk (non-diabetic) population. The growth rates in fetuses of women with satisfactory diabetic control (HbA1c < 6.5%) and unsatisfactory control (HbA1c > or = 6.5%) in the three trimesters were compared. RESULTS: A total of 174 diabetic pregnancies were included and a total of 997 ultrasound scans were performed. The growth rates for fetuses of mothers with diabetes mellitus were significantly higher than for those in the low-risk population. The z-scores for biparietal diameter, femur length, and fetal abdominal area were 0.18, 0.59 and 1.44, respectively. Fetuses of diabetic mothers with high HbA1c in the first trimester had significantly greater fetal abdominal area growth rate than those with normal HbA1c (fetal abdominal area z-score of 1.7 vs. 0.75, P = 0.009). Although the fetal abdominal area z-scores in fetuses of diabetic mothers with high HbA1c in the second or third trimesters were also higher than those with normal HbA1c levels, the differences did not reach statistical significance. Maternal obesity did not influence the fetal growth rate. CONCLUSION: The rate of growth of fetuses of diabetic mothers differs from that of the normal population. Growth acceleration persists until the late third trimester. Moreover, periconceptional glucose control appears to have a significant effect on accelerated growth of the fetal abdominal area.  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