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   3208526篇
  免费   233028篇
  国内免费   7146篇
耳鼻咽喉   43839篇
儿科学   104396篇
妇产科学   86938篇
基础医学   469933篇
口腔科学   89515篇
临床医学   299319篇
内科学   613805篇
皮肤病学   68628篇
神经病学   258205篇
特种医学   118298篇
外国民族医学   810篇
外科学   470410篇
综合类   69730篇
现状与发展   13篇
一般理论   1224篇
预防医学   261556篇
眼科学   74143篇
药学   238264篇
  16篇
中国医学   6827篇
肿瘤学   172831篇
  2021年   25812篇
  2019年   26711篇
  2018年   37039篇
  2017年   27935篇
  2016年   30916篇
  2015年   35076篇
  2014年   49127篇
  2013年   74967篇
  2012年   102803篇
  2011年   109546篇
  2010年   64790篇
  2009年   60568篇
  2008年   101939篇
  2007年   108404篇
  2006年   109257篇
  2005年   105784篇
  2004年   101016篇
  2003年   96901篇
  2002年   93706篇
  2001年   142440篇
  2000年   146401篇
  1999年   123255篇
  1998年   36550篇
  1997年   32163篇
  1996年   32169篇
  1995年   30426篇
  1994年   28252篇
  1993年   26575篇
  1992年   96762篇
  1991年   94936篇
  1990年   92381篇
  1989年   88559篇
  1988年   81718篇
  1987年   80151篇
  1986年   75681篇
  1985年   72541篇
  1984年   54223篇
  1983年   46342篇
  1982年   27757篇
  1979年   49984篇
  1978年   35720篇
  1977年   29573篇
  1976年   28577篇
  1975年   30254篇
  1974年   36534篇
  1973年   35208篇
  1972年   32854篇
  1971年   30979篇
  1970年   28699篇
  1969年   26906篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
Primary chemotherapy administered to breast cancer patientsis the best model to identify baseline features able to predictwhich patients may be most likely to benefit or not from a cytotoxicregimen. In the March issue of Annals of Oncology two papersevaluated the predictive role of immunohistochemical p53 expressionon  相似文献   
83.
84.
85.
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   
86.
87.
Cutaneous plasmacytosis is a rare disorder characterized by a benign proliferation of mature plasma cells that appears as multiple dark-brown to purplish skin lesions, often associated with polyclonal hypergammaglobulinaemia. We present the case of a 55-year-old Caucasian man who suffered from a cutaneous plasmacytosis associated with two different carcinomas. Cutaneous plasmacytosis seems to be a reactive process because most cases reported are not associated with any apparent underlying disease. Nevertheless, because few reported cases were associated with malignancies, screening of additional neoplasms would be justified.  相似文献   
88.
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   
89.
Patients with multiple system atrophy (MSA) present large changes in blood pressure (BP) due to autonomic disturbances. We analyzed how this change may influence dynamic cerebral autoregulation (DCA). Simultaneous recordings of arterial BP (Finapres) and middle cerebral artery (MCA) blood flow velocity (BFV) (transcranial Doppler) were performed in 10 patients with MSA (61 +/- 12 yr of age) and 12 healthy volunteers (61 +/- 11 yr of age): cerebral BFV response to oscillations in mean BP was studied in the supine position by cross-spectral analysis of mean BP and mean MCA BFV. The DCA was also studied during the decrease in BP the first seconds when standing up from a sitting position by the assessment of the cerebrovascular resistance index (CR; mean BP/mean MCA BFV ratio). The MCA BFV/BP cross-spectral analysis showed a phase for the mid-frequency band (0.07-0.2 Hz) significantly larger in MSA, suggesting more active autoregulation in response to larger changes in BP. Changes in CR reflecting the rate of autoregulation, when standing did not differ between the two groups. These data suggest that dynamic cerebral autoregulation is preserved in MSA.  相似文献   
90.
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