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   32727篇
  免费   2480篇
  国内免费   133篇
耳鼻咽喉   446篇
儿科学   788篇
妇产科学   743篇
基础医学   4272篇
口腔科学   1348篇
临床医学   2767篇
内科学   8032篇
皮肤病学   722篇
神经病学   2809篇
特种医学   967篇
外科学   5149篇
综合类   211篇
一般理论   13篇
预防医学   2247篇
眼科学   818篇
药学   1764篇
  1篇
中国医学   84篇
肿瘤学   2159篇
  2023年   183篇
  2022年   378篇
  2021年   1003篇
  2020年   587篇
  2019年   948篇
  2018年   1177篇
  2017年   746篇
  2016年   833篇
  2015年   986篇
  2014年   1299篇
  2013年   1583篇
  2012年   2527篇
  2011年   2543篇
  2010年   1444篇
  2009年   1270篇
  2008年   1997篇
  2007年   2144篇
  2006年   1904篇
  2005年   1759篇
  2004年   1510篇
  2003年   1314篇
  2002年   1195篇
  2001年   451篇
  2000年   402篇
  1999年   477篇
  1998年   291篇
  1997年   254篇
  1996年   208篇
  1995年   221篇
  1994年   201篇
  1993年   195篇
  1992年   314篇
  1991年   265篇
  1990年   220篇
  1989年   245篇
  1988年   213篇
  1987年   185篇
  1986年   199篇
  1985年   186篇
  1984年   162篇
  1983年   135篇
  1982年   108篇
  1981年   114篇
  1980年   67篇
  1979年   104篇
  1978年   87篇
  1977年   66篇
  1976年   69篇
  1975年   68篇
  1973年   76篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
In an effort to evaluate whether differences exist in the hypothalamic-pituitary-thyroid axis of depressed children, a thyrotropin releasing hormone (TRH) stimulation test was administered to 55 prepubertal subjects who were divided into three groups matched for age and sex: a depressed group (endogenous N = 15, nonendogenous N = 15), a psychiatric nondepressed control group (N = 16), and a normal control group (N = 9). Each subject was tested at two dosages of TRH, 2 micrograms/kg and 7 micrograms/kg. Increasing age and female sex were positively correlated with a greater thyroid stimulating hormone (TSH) response. TSH response to TRH was examined with subjects reclassified by severe suicidal ideation, severe aggression, and parental history of alcoholism. Results of this study are contrasted with the adult psychiatric literature.  相似文献   
52.
Between 4/1986 to 1/1989, 74 orthotopic liver transplantation were performed in 62 patients (62 first liver transplants, 10 as second graft and two as a third graft); 57 in adults and 17 in children. The main indication for the operation was liver cirrhosis (61.4%) (the most frequent etiology was alcoholic cirrhosis, 28.5%). Six cirrhotic patients had a hepatocarcinoma (9.6%). Two received a liver and kidney transplant due to terminal renal insufficiency and hemodialysis. The most frequent indication in children was biliary atresia (33.3%). Six patients had a fulminal liver failure (9.6%). AB0 blood group compatibility was identical in 87.5%, compatible in six and incompatible in three patients. Total orthotopic liver transplantation was performed in 67 patients, and size-reduced liver was indicated in 7 patients. Extracorporeal veno-venous bypass was used in adults but never in children. In 93.1% of the transplants a single hepatic artery was anastomosed to the recipient and in 6.9% a double anastomosis was performed. In 62.5% of the patients a end-to-end choledocho-choledochostomy was performed and in 34.8% hepatico-jejunostomy was indicated. Three months postoperative mortality rate was 12.9%. Arterial stenosis and thrombosis were the most frequent complication.  相似文献   
53.
Short-chain alkyl esters of L-dopa were administered to rats and mice via oral and rectal routes. Plasma L-dopa esters and L-dopa were determined in the systemic and portal circulation by HPLC. A comparison of isopropyl, butyl, and 4-hydroxybutyl esters of L-dopa demonstrated significantly higher levels of the esters in both systemic and portal blood samples following rectal administration than following oral administration. In most cases, oral administration resulted in nondetectable (<0.01 µg/ml) levels of the esters in plasma. Correspondingly, the plasma levels of L-dopa itself were consistently higher following rectal administration. At very high oral doses (500 mg L-dopa equivalents/kg body weight), systemic plasma levels of the butyl ester could be detected (1.25 µg/ml at 10 min), which might indicate saturation of the esterase activity of the small intestine. These studies indicate that the systemic availability of L-dopa from short-chain alkyl esters of L-dopa may be best optimized by rectal administration, which avoids the relatively high esterase activity characteristic of the small intestine.  相似文献   
54.
55.
We report on 7 patients (6 M, 1 F) with Coffin-Lowry syndrome who have a sensorineural hearing deficit in addition to developmental delay and characteristic facial changes. One of the patients also had a history of premature exfoliation of primary teeth. These are previously unappreciated clinical signs that may aid in the early diagnosis of Coffin-Lowry syndrome. Early diagnosis and recognition of a hearing deficit in the patient can lead to the use of hearing aids to help the patient achieve his or her full potential. These “;new”; clinical manifestations expand the phenotype of Coffin-Lowry syndrome and constitute an additional indication of pleiotropy. © 1993 Wiley-Liss, Inc.  相似文献   
56.
The results of the multiple regression and correlation analysis between perinatal mortality and social and health care variables in Spanish provinces between 1975 and 1979 are presented. Although the perinatal mortality rates of Spanish provinces correlate significantly with a series of socioeconomic variables (family income available per capita, percentage of active population in primary sector, educational level of women at childbearing age) and health care variables (active obstetricians per 1000 live births and active pediatricians per 1000 live births), the multiple correlation and regression analysis has shown that the most important variable is the family income available per capita: 44% of the variability of perinatal mortality in Spanish provinces can be accounted for by this factor. By regression analysis, it is also possible to predict a decrease of 0.065 points in perinatal mortality for every additional 1000 pesetas in the family income available per capita.  相似文献   
57.
58.
A total of 186 blood samples from 24 HIV-1 seropositive hemophiliac patients, monitored every four months for 29 months, were investigated for the presence of viral antigen in plasma. In addition, peripheral blood mononuclear cells (PBMC) were cultured for HIV-1, using normal PBMC as a target for replication. Antigenemia was detected in 51 % of the patients and from PBMC in 87.5 % of the patients. The incidence of HIV isolation in asymptomatic patients (42.8 %) was similar to that found in symptomatic patients (51.4 %). Patients with opportunistic infections had a higher incidence of lymphocytic viremia (p<0.05). Plasma viremia was closely associated (p<0.05) with low CD4+ counts and infection progression. The persistence of antigenemia was also a marker of a poor clinical course. In treated patients, plasma viremia was the marker that better correlated with the clinical course, and it did not appear during the first nine months of therapy. Zidovudine doses of >500 mg/day significantly lowered the appearance of antigenemia and lymphocytic viremia (p<0.05).  相似文献   
59.
Access to food and the amount consumed were investigated within a group of 45 children aged 33 to 60 months, among whom growth stunting was common. Children were observed throughout 1 day; all foods offered and consumed were weighed, and food-related behaviors noted. Children ate frequently, at least 2 meals and an average of 7.4 +/- 2.6 snacks daily. Children had access to 2029 +/- 575 kcal (8493 +/- 2407 kJ) yet only consumed 1528 +/- 343 kcal (6396 +/- 1436 kJ) daily; thus food availability was not restricting intake. A higher proportion of snacks than meals (85 per cent vs. 71 per cent) was consumed. Children requested foods frequently (x = 9.2 +/- 4.3) and 76 per cent of requests were fulfilled. Neither amount of accessible food nor amount consumed differed by age, gender, or socioeconomic status. The importance of the child's role in determining food intake, and of snacking to overall food consumption, was demonstrated.  相似文献   
60.
In every Radiation Oncology Department there is a group of patients referred for curative radiotherapy and within this group of patients there is a subset of patients who present the most difficult of treatment scenarios, maximum tumor dose and minimum spinal cord dose. The case to be presented involved the use of a head and neck five field technique of which three fields were treated isocentrically with the remaining two fields being electron boosts. It is from these patients that we extend to the maximum our planning capabilities.  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