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   3095798篇
  免费   230284篇
  国内免费   5494篇
耳鼻咽喉   44810篇
儿科学   103044篇
妇产科学   88821篇
基础医学   444153篇
口腔科学   90089篇
临床医学   270335篇
内科学   596924篇
皮肤病学   66407篇
神经病学   247109篇
特种医学   121772篇
外国民族医学   1060篇
外科学   473864篇
综合类   72318篇
现状与发展   4篇
一般理论   1018篇
预防医学   237991篇
眼科学   73198篇
药学   231899篇
  5篇
中国医学   5842篇
肿瘤学   160913篇
  2018年   29503篇
  2016年   25365篇
  2015年   29248篇
  2014年   40831篇
  2013年   62623篇
  2012年   84820篇
  2011年   90400篇
  2010年   53650篇
  2009年   50908篇
  2008年   86461篇
  2007年   92382篇
  2006年   93752篇
  2005年   91384篇
  2004年   89013篇
  2003年   85547篇
  2002年   84130篇
  2001年   137100篇
  2000年   141289篇
  1999年   120309篇
  1998年   34478篇
  1997年   31055篇
  1996年   30946篇
  1995年   29498篇
  1994年   27807篇
  1993年   26260篇
  1992年   98193篇
  1991年   95846篇
  1990年   94146篇
  1989年   91236篇
  1988年   84978篇
  1987年   83836篇
  1986年   80027篇
  1985年   76809篇
  1984年   57851篇
  1983年   49940篇
  1982年   29794篇
  1981年   26383篇
  1979年   55295篇
  1978年   38861篇
  1977年   32971篇
  1976年   31272篇
  1975年   33847篇
  1974年   40786篇
  1973年   39299篇
  1972年   36942篇
  1971年   34521篇
  1970年   32258篇
  1969年   30427篇
  1968年   28467篇
  1967年   25629篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
102.
Summary:  The immune system is capable of recognizing and eliminating an enormous array of pathogens due to the extremely diverse antigen receptor repertoire of T and B lymphocytes. However, the development of lymphocytes bearing receptors with unique specificities requires the generation of programmed double strand breaks (DSBs) coupled with bursts of proliferation, rendering lymphocytes susceptible to mutations contributing to oncogenic transformation. Consequently, mechanisms responsible for monitoring global genomic integrity must be activated during lymphocyte development to limit the oncogenic potential of antigen receptor locus recombination. Mutations in ATM (ataxia-telangiectasia mutated), a kinase that coordinates DSB monitoring and the response to DNA damage, result in impaired T-cell development and predispose to T-cell leukemia. Here, we review recent evidence providing insight into the mechanisms by which ATM promotes normal lymphocyte development and protects from neoplastic transformation.  相似文献   
103.
Comment     
  相似文献   
104.
105.
OBJECTIVE: To evaluate the prenatal distribution, associated conditions and outcome of the different types of right aortic arch (RAA) detected in fetal life. METHODS: This was a retrospective review of all cases of RAA detected prenatally between 1998 and 2005 in two tertiary referral centers. RESULTS: In the study period 71 cases of RAA were detected; 26 (37%) had RAA with aberrant left subclavian artery, 23 (32%) had RAA with mirror-image branching, 20 (28%) had RAA of unknown type and two (3%) had double aortic arch. While 20/26 cases with RAA and aberrant left subclavian artery were isolated findings, all 23 cases with RAA and mirror-image branching were associated with cardiac defects, namely tetralogy of Fallot (43%) or pulmonary atresia with ventricular septal defect (22%). Of the 20 cases with RAA, 19 of unknown type were associated with heterotaxy syndromes and had additional cardiac malformations and ambiguities of the situs. The two cases with DAA were isolated findings. Seven cases in our series (10%) had a microdeletion 22q11 and these were significantly associated with extracardiac malformations. The outcome in our series depended solely on the associated cardiac and extracardiac malformations, with the exception of one infant with isolated DAA, in whom a surgical correction was warranted. CONCLUSIONS: RAA detected in fetal life is associated frequently with other cardiac/non-cardiac malformations, heterotaxy syndromes and microdeletions 22q11. The associated conditions vary depending on the branching type of the brachiocephalic vessels and the presence of extracardiac malformations.  相似文献   
106.
107.
108.
BACKGROUND CONTEXT: Substantial variation exists regarding the use of sedation before interventional spine techniques. Patient preference should play an important role in decision making regarding the need for sedation. However, little is known about patients' anxiety levels before spinal injections and their perceptions about the necessity of sedation. PURPOSE: To determine patient perception for need for sedation before epidural steroid injections and zygapophyseal joint injections. STUDY DESIGN/SETTING: Survey of consecutive spinal injection patients in an outpatient spine center. PATIENT SAMPLE: 500 consecutive lumbar, thoracic, and cervical patients receiving spinal injections. OUTCOME MEASURES: A 12-item questionnaire assessing patients' perceived anxiety before to a spinal injection. METHODS: Subjects were given the questionnaire after their spinal injection. Percentages requesting sedation for a first and potential second procedure were assessed. Additionally, anxiety level and pain rating, location of injection, age, sex, and other medication use were analyzed to determine the effect on the request for sedation. RESULTS: 17% of patients questioned requested sedation before an injection, and 28% would request sedation if they were to have a second injection. CONCLUSIONS: Routine sedation before diagnostic and therapeutic injections is not necessary as the majority of patients would not request sedation before the procedure when given the option. However, in some patients sedation is indicated, and all patients would benefit from educational material on sedation before the injection.  相似文献   
109.
110.
AIMS: To report clinical outcomes of a large series of cases with advanced thyroid cancer. STUDY DESIGN: Three hundred and eighty-five patients at the UICC stages III and IV were selected for the study with thyroid cancer. RESULTS: Papillary carcinoma and sclerosing carcinoma have better survival than the Hürthle cell and insular types. Lymphatic metastasis does not appear to worsen the prognosis. All the tumour forms offer the chance of long survival. CONCLUSIONS: Surgical treatment is the primary treatment of thyroid carcinoma. The combined treatments of surgery, metabolic beam therapy, suppressive hormone therapy, radiotherapy and chemotherapy cure a high percentage of patients with the tumour at an advanced stage.  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