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   1287篇
  免费   100篇
  国内免费   4篇
耳鼻咽喉   2篇
儿科学   62篇
妇产科学   30篇
基础医学   193篇
口腔科学   13篇
临床医学   150篇
内科学   334篇
皮肤病学   20篇
神经病学   93篇
特种医学   29篇
外科学   115篇
综合类   7篇
预防医学   120篇
眼科学   16篇
药学   75篇
中国医学   1篇
肿瘤学   131篇
  2023年   16篇
  2022年   21篇
  2021年   40篇
  2020年   16篇
  2019年   40篇
  2018年   38篇
  2017年   28篇
  2016年   37篇
  2015年   36篇
  2014年   48篇
  2013年   67篇
  2012年   102篇
  2011年   116篇
  2010年   49篇
  2009年   48篇
  2008年   96篇
  2007年   79篇
  2006年   89篇
  2005年   85篇
  2004年   64篇
  2003年   61篇
  2002年   44篇
  2001年   12篇
  2000年   15篇
  1999年   20篇
  1998年   6篇
  1997年   14篇
  1996年   8篇
  1995年   9篇
  1994年   3篇
  1992年   8篇
  1991年   3篇
  1989年   6篇
  1988年   5篇
  1987年   2篇
  1985年   3篇
  1984年   2篇
  1983年   4篇
  1982年   3篇
  1981年   2篇
  1979年   3篇
  1978年   3篇
  1977年   4篇
  1976年   2篇
  1975年   3篇
  1974年   4篇
  1973年   2篇
  1972年   3篇
  1969年   4篇
  1968年   6篇
排序方式: 共有1391条查询结果,搜索用时 15 毫秒
991.
992.
The objective of this study was to determine the feasibility of developing and using a voice recognition computerized charting system to record dental clinical examination data. More specifically, the study was designed to analyze the time and error differential between the traditional examiner/recorder method (ASSISTANT) and computerized voice recognition method (VOICE). DMFS examinations were performed twice on 20 patients using the traditional ASSISTANT and the VOICE charting system. A statistically significant difference was found when comparing the mean ASSISTANT time of 2.69 min to the VOICE time of 3.72 min (P less than 0.001). No statistically significant difference was found when comparing the mean ASSISTANT recording errors of 0.1 to VOICE recording errors of 0.6 (P = 0.059). 90% of the patients indicated they felt comfortable with the dentist talking to a computer and only 5% of the sample indicated they opposed VOICE. Results from this pilot study indicate that a charting system utilizing voice recognition technology could be considered a viable alternative to traditional examiner/recorder methods of clinical charting.  相似文献   
993.
A simple and reliable procedure, based on DNA amplification and Hpa II mapping, is proposed for the identification of fetuses at risk for HPA-1a (PlA1) neonatal alloimmune thrombocytopenia which could cause life-threatening haemorrhage, even in early fetal life. This typing procedure for HPA-1 alleles should help in deciding, very early, the therapeutic management of the fetuses at risk.  相似文献   
994.
The maximal exercise ECG in asymptomatic men   总被引:8,自引:5,他引:3       下载免费PDF全文
Lead MC5 bipolar exercise ECG was obtained in 510 asymptomatic males, aged 40 to 65, utilizing the bicycle ergometer, with maximal stress in 71% of the subjects. “Ischemic changes” occurred in 61 subjects, the frequency increasing from 4% at age 40 to 45, to 20% at age 50 to 55, to 37% at age 61 to 65. Subjects having an ischemic type ECG change on exercise had more frequent minor resting ECG changes, more resting hypertension, and a greater incidence of high cholesterol values than subjects with a normal ECG response to exercise, but there was no difference in the incidence of obesity, low fitness, or high systolic blood pressure after exercise. Current evidence suggests that asymptomatic male subjects with an abnormal exercise ECG develop clinical coronary heart disease from 2.5 to over 30 times more frequently than those with a normal exercise ECG.  相似文献   
995.
The purpose of this retrospective study is to define current indications and results of Hartmann's procedure (H). From 1978 to 1989, 86 H were performed, 52 (60%) as emergency surgery. Indications were: colo-rectal cancer (37): 15 complicated and 22 as an elective procedure, diverticular disease acute or complicated (24), ischemic colitis (10), volvulus of the pelvic colon (5), inflammatory bowel disease (4), colonic perforation (3), traumatic hematoma of the sigmoid mesocolon (1). Fourteen patients died after operation (mean age: 79). There was no death after elective H for cancer. Post-operative complications were numerous: pulmonary (25%), abdominal would sepsis or disruption (21%), rectal strump leakage (14%), the later being harmless due to the associated Mickulicz drainage. Seven patients were reoperated on for necrosis of the colonic stoma. Mean initial hospital stay was 31 days. Restoration of the gastrointestinal continuity was done in 27 cases (37% of the surviving patients, 76% of the diverticular diseases). The authors conclude that for complicated diverticular disease H procedure improves survival without preferable continuity. For cancer, H procedure is permanently compromising gastrointestinal in the elderly to hazardous low anastomosis, and to palliative abdomino-perineal resection.  相似文献   
996.
An epidemiologic survey of JCA was carried out in two regions of France, the western part of Paris and Brittany, differing in terms of geological background and demography. The prevalence was 0.77 and 0.100% and the incidence 0.019 and 0.013%, respectively. The type of onset, the course of the disease, the immunological data and the degree of final disability were similar in both regions. These data were compared to other studies and the factors of possible discrepancy analysed.  相似文献   
997.
Bovine serum albumin (BSA) bound to colloid gold particles (BSA-gold; 20 nm diameter) and injected into preimmunized mice was found at ultrastructural level in different locations of the lymph nodes. It was detected particularly in the secondary lysosomes of macrophages and between the cytoplasmic processes of the follicular dendritic cells. Between these processes the gold particles were isolated or grouped in clusters; they were in close contact with cell membranes or embedded in dense material. Colloidal gold injected alone was not retained on these cells. The presence of anti-BSA antibodies in the serum was necessary for trapping of BSA-gold particles on follicular dendritic cells. Injections of BSA alone after BSA-gold had been administered to preimmunized mice eliminated most of the BSA-gold from the dendritic processes. BSA-gold is thus trapped in the form of immune complexes which behave characteristically. BSA-gold is thus a suitable marker for antigen localization. Being small and electron dense it permits more precise location than radioactive markers.  相似文献   
998.
In this study, we report the exact localization and substitutional characterization of a B-cell epitope domain at the N-terminus of the preS2 region of the hepatitis B surface antigen. A set of deletion variants containing preS2 sequences of different length was generated on the basis of frCP as a carrier. It was found after Western blot analysis that three monoclonal antibodies (MAbs) (2-11B1, 3-11C2, HB.OT10) recognized the linear preS2 sequence within the amino acid (aa) stretch 3-WNSTTFHQTLQDP-13. The importance of each aa residue of the epitope was proved by comparison of antibody binding to alanine-substituted peptides in both free-peptide and Pepscan variants.  相似文献   
999.
1000.
The few previous studies of hypospadias and smoking have suggested either no association or a reduced risk. This study, which uses data from the National Birth Defects Prevention Study, a multi-state, population-based case-control study, includes data on males born with severe hypospadias (i.e. the urethra opens at the penile shaft, scrotum or perineum) from 1997 to 2000. Non-malformed, liveborn male controls were selected randomly from birth certificates or from birth hospitals. Maternal interviews were completed by telephone with 453 case mothers and 1267 control mothers. Maternal smoking was not associated with hypospadias risk. For example, during the third month of pregnancy, smoking < 0.5 pack/day had an odds ratio (OR) of 1.1 [95% CI 0.6, 1.9]; 0.5 pack/day, 0.6 [0.4, 1.1]; and > or = 1 pack/day, 0.8 [0.4, 1.6]. Exposure to any secondhand smoke at home during the third month of pregnancy showed an OR of 0.6 [95% CI 0.4, 1.0], and exposure at work or school, an OR of 0.7 [0.5, 1.1]. Similar risks were observed for other months during the periconceptional period, and adjustment for several potential confounders did not substantially alter results. This analysis does not confirm a recent report suggesting that maternal smoking is associated with a reduced risk of having offspring with hypospadias.  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