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   919810篇
  免费   75622篇
  国内免费   5826篇
耳鼻咽喉   13302篇
儿科学   25375篇
妇产科学   26086篇
基础医学   131481篇
口腔科学   26405篇
临床医学   82864篇
内科学   173412篇
皮肤病学   17625篇
神经病学   73497篇
特种医学   37383篇
外国民族医学   223篇
外科学   141960篇
综合类   32573篇
现状与发展   21篇
一般理论   266篇
预防医学   70769篇
眼科学   22131篇
药学   70766篇
  62篇
中国医学   4581篇
肿瘤学   50476篇
  2021年   8061篇
  2018年   9464篇
  2016年   8348篇
  2015年   10329篇
  2014年   14347篇
  2013年   19467篇
  2012年   26966篇
  2011年   28535篇
  2010年   16716篇
  2009年   15223篇
  2008年   25543篇
  2007年   27624篇
  2006年   27484篇
  2005年   27136篇
  2004年   25705篇
  2003年   24771篇
  2002年   23610篇
  2001年   36902篇
  2000年   37645篇
  1999年   32211篇
  1998年   10123篇
  1997年   9402篇
  1996年   9130篇
  1995年   8608篇
  1994年   8218篇
  1992年   27038篇
  1991年   26435篇
  1990年   25913篇
  1989年   24919篇
  1988年   23479篇
  1987年   23080篇
  1986年   21935篇
  1985年   21251篇
  1984年   16493篇
  1983年   14081篇
  1982年   8900篇
  1981年   8249篇
  1979年   16814篇
  1978年   12148篇
  1977年   10203篇
  1976年   9345篇
  1975年   10181篇
  1974年   12681篇
  1973年   12163篇
  1972年   11563篇
  1971年   10708篇
  1970年   10230篇
  1969年   9926篇
  1968年   8918篇
  1967年   8242篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
Computed tomography of the brain in the Smith-Lemli-Opitz syndrome   总被引:1,自引:0,他引:1  
Computed tomographic (CT) scans of the brain in a child with Smith-Lemli-Opitz syndrome revealed enlargement of the ventricular system, hypoplasia of the cerebellum, and abnormal thickening of the gray matter, consistent with pachygyria. These findings have been previously noted in autopsies performed on patients with this disorder. We conclude that CT scanning is a valuable tool in the evaluation of children suspected of having the Smith-Lemli-Opitz syndrome.  相似文献   
103.
In 1985, we initiated a prospective clinical trial to evaluate the risk of recurrence for superficial bladder cancer. Up to now, 41 patients subjected to TUR have subsequently been monitored by immunocytology with a monoclonal antibody (mab 486 p) recently developed in our laboratory. Of these patients, 15 (36.6%) remained marker-negative and received no prophylactic therapy. There was only one recurrence (6.7%) in this subset of patients, whereas 10 out of 26 (38.5%) marker-positive patients have so far developed recurrent malignancies. In all cases, the conversion of immunocytological characteristics preceded visible recurrence by 2-5 months. These preliminary results indicate that immunocytology might make it possible to identify patients at low risk of recurrence more accurately than has so far been feasible with standard cytology or flow-cytometry.  相似文献   
104.
105.
Biological oxidation of 2,4-diamino-6-substituted pyrimidines have been studied using hepatic microsomes from various mammalian species. The nature of the enzyme(s) involved in the oxidation has been elucidated using various enzyme inhibitors and inducing agents. The 3-N-oxides were formed with 6-piperidino-, 6-diethylamino-, 6-methyl-, and 6-chloro-substituted 2,4-diaminopyrimidines: no evidence of 1-N-oxide formation was obtained. With the 6-hydroxy-, 6-amino-, and unsubstituted 2,4-diaminopyrimidines and melamine, no N-oxidative metabolite was detected. The differences in N-oxide formation was discussed in terms of the effect of substituents on tautomerism and electron distribution. The N-oxygenation was mediated via a cytochrome P450 dependent system.  相似文献   
106.
Positron emission tomography (PET) with fluorodeoxyglucose (FDG), magnetic resonance imaging (MRI), and CT were carried out in a patient with Alzheimer's disease 16 months before he died. At autopsy, the gross appearance of the brain correlated with MRI and CT, which showed some regional atrophy. These were much less revealing than PET, which correlated with microscopic findings of neuronal loss and proliferation of glia. In areas of moderately impaired local cerebral metabolic rate of glucose, as revealed by reduced FDG uptake, there was some gliosis, primarily around the numerous senile plaques. In areas of severe metabolic impairment, there was a profound loss of neurons, extensive gliosis, and a diminished appearance of plaques. PET-FDG is a better measure of the severity of Alzheimer's disease than MRI or CT, because it reflects the degree of neuronal pathology.  相似文献   
107.
108.
Neutropenic enterocolitis in adults with acute leukemia   总被引:2,自引:0,他引:2  
Neutropenic enterocolitis has been previously described only by case reports and literature reviews. Of 499 adults with acute leukemia seen over a 23-year period (1962 to 1985), 13 cases (2.6%) of neutropenic enterocolitis have been reported. Eleven of these 13 patients were profoundly neutropenic (mean white blood cell count, 472/cu mm) and developed abdominal symptoms during either initial induction or relapse of acute leukemia. Histologic confirmation was available in ten cases, five cases after surgical resection and five cases at autopsy after nonoperative management. Three patients with isolated ileocecal inflammation without infarction at the time of surgery were successfully managed without resection. Five patients treated with surgery died four to 64 weeks postoperatively (mean survival, 21.6 weeks) of nonsurgical complications of leukemia. Three patients were still alive, one patient 42 months after right hemicolectomy and two patients five months after exploration only. All five patients managed medically died an average of 1.4 days (range, zero to four days) after the onset of abdominal pain. Survival in patients with acute leukemia who develop neutropenic enterocolitis is determined by early recognition and appropriate surgical exploration that can be expected to yield an acceptable operative mortality.  相似文献   
109.
Clinical experience of phototherapy for non-haemolytic hyperbilirubinaemia in 3999 infants in Kandang Kerbau Hospital, Singapore, is documented. Phototherapy was most effective in extremely preterm infants with very low birth weight (gestation less than or equal to 32 weeks, birth weight less than or equal to 1500 g) and least effective in full term infants with very low birth weight (gestation greater than or equal to 37 weeks, birth weight less than or equal to 1500 g) and large preterm infants (gestation less than 37 weeks, birth weight greater than 2270 g). Overall, phototherapy was effective in almost all the infants, with a failure rate of only 2.00/1000 infants. No characteristic features common to all the failures could be detected. The bilirubin rebound was usually mild; repeat phototherapy was required in only 30 infants (7.50/1000), with the response to the second exposure comparable to that to the first. No infant required a third exposure. All the infants tolerated phototherapy well, none developing any illness that could be attributed to the treatment. This clinical experience shows that phototherapy for the treatment of nonhaemolytic hyperbilirubinaemia is effective and safe.  相似文献   
110.
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