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   3660篇
  免费   211篇
  国内免费   9篇
耳鼻咽喉   10篇
儿科学   174篇
妇产科学   55篇
基础医学   591篇
口腔科学   164篇
临床医学   267篇
内科学   637篇
皮肤病学   58篇
神经病学   329篇
特种医学   343篇
外科学   514篇
综合类   34篇
一般理论   2篇
预防医学   218篇
眼科学   78篇
药学   265篇
  1篇
中国医学   1篇
肿瘤学   139篇
  2021年   36篇
  2020年   23篇
  2019年   45篇
  2018年   46篇
  2017年   46篇
  2016年   41篇
  2015年   52篇
  2014年   69篇
  2013年   76篇
  2012年   139篇
  2011年   136篇
  2010年   103篇
  2009年   96篇
  2008年   113篇
  2007年   134篇
  2006年   116篇
  2005年   117篇
  2004年   121篇
  2003年   117篇
  2002年   110篇
  2001年   103篇
  2000年   109篇
  1999年   105篇
  1998年   85篇
  1997年   96篇
  1996年   73篇
  1995年   71篇
  1994年   73篇
  1993年   64篇
  1992年   71篇
  1991年   59篇
  1990年   53篇
  1989年   76篇
  1988年   104篇
  1987年   94篇
  1986年   81篇
  1985年   86篇
  1984年   52篇
  1983年   54篇
  1982年   50篇
  1981年   44篇
  1980年   39篇
  1979年   37篇
  1978年   41篇
  1977年   34篇
  1975年   35篇
  1974年   23篇
  1973年   22篇
  1972年   26篇
  1969年   32篇
排序方式: 共有3880条查询结果,搜索用时 31 毫秒
11.
12.
13.
14.
Introduction and background A 3-year-old Bosnian girl with a large symptomatic brainstem and multiple supratentorial cavernous angiomas, who underwent neurosurgical treatment, is presented. As multiple cavernomas are more common in familial cases, genetic analyses and neuroradiological imaging were performed in the patient and her parents to see whether there was any evidence for inheritance. This information is important for genetic counseling and provision of medical care for at-risk relatives. Currently, no recommendation is available on how to manage these cases.Results Genetic analyses demonstrated a novel CCM1 frameshift mutation (c.1683_1684insA; p.V562SfsX6) in the child and the asymptomatic 27-year-old mother. Sensitive gradient-echo magnetic resonance imaging of the mother revealed multiple supratentorial lesions, whereas analogous imaging of the father showed no pathological findings.Conclusion This case exemplifies that seemingly sporadic cases with multiple lesions might well be hereditary and that presymptomatic genetic testing of family members may identify relatives for whom clinical and neuroradiological monitoring is indicated.  相似文献   
15.
Hodgkin disease: CT of the thymus   总被引:2,自引:0,他引:2  
Heron  CW; Husband  JE; Williams  MP 《Radiology》1988,167(3):647-651
The computed tomography (CT) scans in two groups of patients with Hodgkin disease were reviewed to determine the frequency of thymic enlargement. In 50 CT scans from 50 patients with evidence of thoracic disease on CT scans who were examined for primary staging, the thymus was enlarged in 15 of 50 (30%). Fifty CT scans were obtained from 44 patients at the time of 50 separate episodes of known or suspected relapse. Relapse occurred in the mediastinum in 12 episodes, lung parenchyma in five, and both sites in one. Thymic enlargement thought to be due to involvement by disease was present in seven of 18 (38%). Mediastinal disease was associated with thymic enlargement in all but one patient in whom a thymic cyst developed after radiation therapy. Differentiation of thymic enlargement from enlarged superior mediastinal lymph nodes was easily made in all but two patients. Thymic enlargement in the absence of lymph node enlargement may indicate a different disease, since isolated Hodgkin disease of the thymus is uncommon. Primary thymic tumor should be considered initially, whereas after treatment, rebound hyperplasia of the thymus may be the cause of enlargement.  相似文献   
16.
The ageing phenomenon exhibited by the ascomycetous fungus Podospora anserina can be either delayed or induced by either different carbon sources or effectors. As these effects seem to have analogy to catabolite-repression of respiratory genes, experiments concerning respiratory functions have been carried out. Ageing is parallelled by switching from cytochrome c-oxidase-mediated respiration to alternative, cyanide-resistant respiration for reasons still unknown. The latter is always accompanied by appearance of the phenol oxidizing enzyme laccase (EC 1.10.3.2), which seems to act as an alternative oxidase. The existence of a second, non-mitochondrially encoded respiratory pathway relieves the selective pressure on mitochondria leading to disintegrated, non-functional mtDNA and thereby whole mitochondria which accumulate in the hyphal cells. Mutants lacking cytochrome c-oxidase aa3 or laccase have stable mitochondrial populations and live eternally.  相似文献   
17.
Solitary bronchioloalveolar carcinoma: CT criteria   总被引:14,自引:0,他引:14  
The computed tomographic (CT) scans of 30 patients with solitary bronchioloalveolar carcinoma were reviewed. Common features at CT included the peripheral or subpleural location of a pulmonary mass (25 cases), pseudocavitation (18 cases), heterogeneous attenuation (17 cases), irregular margins forming a star pattern (22 cases), and pleural tags (21 cases). Using these CT criteria, four independent observers attempted to identify cases of bronchioloalveolar carcinoma from a larger sample of lung cancers and benign lesions by categorizing a series of test cases into four probability categories. Although the bronchioloalveolar carcinomas were correctly ranked in the two highest probability categories 75% of the time (in 45 of 60 cases), there was considerable overlap with other lung lesions, particularly with adenocarcinoma and large cell undifferentiated carcinoma. However, even though the typical features of bronchioloalveolar carcinoma are not invariable or highly specific, they are characteristic enough to suggest the diagnosis.  相似文献   
18.
In spite of a reduced rate of new occurrence, gastric cancer is still one of the most common causes of cancer related mortality. Crucial to the value of systemic therapy are the 50% of patients who already have metastasizing or locally advanced stages at first diagnosis which are not surgically curable. In comparison to merely supportive therapy, controlled studies have shown the unmistakable value of chemotherapy. Recently, cisplatin and infused 5-fluorouracil (5-FU) based combination treatments have become the therapeutic standard. The internationally best studied scheme is the “ECF” combination. The taxane and irinotecan group has limited value as monotherapy and is used in combination studies, as are oral fluoropyrimidine and oxaliplatin, with other substances. With the introduction of numerous, new, effective cytostatics, a whole series of combinations are being tested. The main aims of these studies are, on the one hand, lowered toxicity or ease of use with equivalent effectiveness, and on the other hand, higher effectiveness without significantly increased toxicity.  相似文献   
19.
20.
Fifteen partial parotid salivary gland resection specimens interpreted as benign lymphoepithelial lesion (BLL) were accessioned by our surgical pathology service between January 1983 and December 1986. Twelve of the specimens were removed from 11 prison inmates referred to our hospital, a patient subgroup constituting the source of only 2% of surgical pathology specimens in general. All prison inmates with BLL had a history of intravenous drug use, had developed unexplained lymphadenopathy concurrently with the parotid gland enlargement, and had suspected human immunodeficiency virus (HIV) infection (serologically confirmed in two). Histopathologic features of the parotid gland specimens included atypical follicular hyperplasia and follicular involution, resembling lymph node changes of HIV infection. The clinical and pathologic findings in these cases suggest an association between HIV infection and BLL, and support a previously proposed mechanism for the development of BLL through progressive enlargement of intraparotid lymph nodes.  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