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   3217187篇
  免费   240997篇
  国内免费   8170篇
耳鼻咽喉   43696篇
儿科学   104452篇
妇产科学   87198篇
基础医学   462035篇
口腔科学   89443篇
临床医学   292687篇
内科学   629678篇
皮肤病学   73385篇
神经病学   257551篇
特种医学   124063篇
外国民族医学   743篇
外科学   488302篇
综合类   70596篇
现状与发展   14篇
一般理论   1167篇
预防医学   257170篇
眼科学   73461篇
药学   235394篇
  15篇
中国医学   5971篇
肿瘤学   169333篇
  2018年   35051篇
  2017年   26739篇
  2016年   30741篇
  2015年   34572篇
  2014年   48666篇
  2013年   73521篇
  2012年   97244篇
  2011年   103931篇
  2010年   62876篇
  2009年   60043篇
  2008年   97270篇
  2007年   103790篇
  2006年   105155篇
  2005年   102002篇
  2004年   97326篇
  2003年   94185篇
  2002年   90875篇
  2001年   146410篇
  2000年   150262篇
  1999年   126689篇
  1998年   38030篇
  1997年   33515篇
  1996年   34243篇
  1995年   33248篇
  1994年   30741篇
  1993年   28932篇
  1992年   100962篇
  1991年   98526篇
  1990年   95841篇
  1989年   92023篇
  1988年   84923篇
  1987年   83379篇
  1986年   78505篇
  1985年   75497篇
  1984年   56886篇
  1983年   48321篇
  1982年   29341篇
  1981年   26424篇
  1979年   52195篇
  1978年   37564篇
  1977年   31354篇
  1976年   29695篇
  1975年   31623篇
  1974年   37747篇
  1973年   35908篇
  1972年   33766篇
  1971年   31649篇
  1970年   29010篇
  1969年   27625篇
  1968年   25454篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
A microfluorometric method was used to determine the nuclear DNA content in the nasopharyngeal carcinomas (NPC) of 25 patients treated before 1983. Eleven patients are still alive with no evidence of disease (NED), while the rest died of their disease (DOD). All of the patients received a cycle of radiotherapy, while some also received chemotherapy or neck dissections. The neoplastic cells studied were taken from the original biopsy blocks, deparaffinized, isolated by enzymatic treatment and mechanical fragmentation, and then Feulgen-stained. The cytofluorometric measurement was carried out by a microphotometer equipped for fluorescence excitation and connected to a computer. This method allowed us to construct a histogram of the DNA content in the neoplastic cells. Different neoplastic classes were identified and represent the heteroclonality of the tumor, which can be expressed by the heteroclonality index (HCT). From the collected data it appears that the NED patients all had a low HTC (less than 1) and only 7 of the DOD patients had low HTCs (less than 1). Six of the DOD patients with a low HTC were in advanced stages of their tumor at the time of diagnosis, while the remaining patient did not complete his treatment. Our results show that the DNA analysis of the NPC cell population may offer a useful tool in predicting the biological behavior of this tumor and also improving its treatment.  相似文献   
992.
Nonsyndromal autosomal recessive profound childhood deafness will affect about one in 4000 children in western Europe. A nonsyndromal autosomal recessive type of profound childhood deafness was thought to be the cause of deafness in at least eight and probably 12 children from a large family with various consanguineous matings and other family interrelations. Audiograms of all affected deaf children showed a profound childhood deafness with only a very slight variation. Audiometric examinations, such as pure-tone audiometry, high-frequency audiometry, stapedial reflexes, and Bekesy audiometry, of ten obligate or presumed carriers did not show any significant findings that would allow identification of carriers of this autosomal recessive gene. Families like this one seem to be very rare. Large clinically well-studied families like this one are indispensable for gene linkage studies of nonsyndromal autosomal recessive types of profound childhood deafness. Such studies should make it possible to trace the origin of these types of childhood deafness at an early age. In consequence, carrier detection should also become available.  相似文献   
993.
After ingesting or inhaling laundry detergent powder, eight children required hospital admission. The predominant symptoms were stridor, drooling, and respiratory distress. All but one patient underwent endoscopy of the airways and the esophagus, five children were admitted to the intensive care unit, and four children required endotracheal intubation. Laundry detergent ingestions are generally considered to have minor consequences, and there exists a paucity of literature on the subject. Evidence of significant morbidity incurred because of ingestion or inhalation of sodium carbonate-containing laundry detergent powder is presented, together with a review of the existing literature.  相似文献   
994.
995.
996.
Twenty two patients (age range: 1 month to 11 years) were treated for congenital diaphragmatic defects (excluding hiatus hernia) in the six year period 1983-8. Presenting features were failure to thrive (n = 7), abdominal pain and vomiting (n = 4), chronic respiratory symptoms (n = 3), and inability to wean from ventilatory support (n = 3). The defect was an incidental finding in five patients. Operative repair was performed with no mortality or serious postoperative morbidity. Dramatic improvement occurred in 15 of the 17 symptomatic patients. Awareness of the differential diagnosis should avoid delay in diagnosis or inappropriate treatment. Surgical correction is strongly recommended in all cases.  相似文献   
997.
998.
999.
The incidence and mortality of acute epiglottitis were retrospectively analysed covering a 12-year period, 1975-1987. The diagnosis was made by the laryngoscopic findings in 95% of patients. Based on 902 hospitalized patients, a mean annual incidence of 4.9 cases per 100,000 children and adults was found. Although adult patients predominated (60%), the incidence was far higher in children, 13.8 per 100,000 compared with 3.9 per 100,000 in adults. Two peaks in incidence were identified, one for the youngest children, and the second for young adults (15-29 years). Over the years the incidence varied little in adults, but decreased significantly in children over the last 6 years studied. The data presented indicate acute epiglottitis to be a more frequent disorder than previously believed but with less risk of a fatal outcome. The mortality rate was below 1% in children and adults and the annual incidence of death from acute epiglottitis was estimated at 0.5 cases per million. The primary admission of these patients to ENT units seems to be the single factor having the most powerful impact on mortality.  相似文献   
1000.
Tumor material from 91 patients with squamous cell carcinoma of the head and neck was transplanted subcutaneously in athymic nude mice. In the first (man to mouse) passage, the calculated mean probability of tumor take in a single mouse was 11%. The probability of growth in the first passage was significantly better for moderately and poorly differentiated tumors than for well-differentiated tumors. Also, the implantation of lymph node material resulted in a significantly better tumor take rate than material taken from a primary tumor. Transplantability was not dependent on the following characteristics: localization, T or N stage of the tumor, or the sex of the patients. Once growth was established, all variables studied had no influence on the probability of growth in the subsequent mouse passages. A relationship between tumor growth in nude mice and patient prognosis could not be found. When transplanting head and neck squamous cell carcinoma in nude mice, it has to be recognized that some tumor characteristics will influence the success of tumor growth.  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