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   8959篇
  免费   585篇
  国内免费   123篇
耳鼻咽喉   121篇
儿科学   157篇
妇产科学   175篇
基础医学   1171篇
口腔科学   118篇
临床医学   649篇
内科学   2218篇
皮肤病学   483篇
神经病学   512篇
特种医学   480篇
外科学   1123篇
综合类   170篇
一般理论   4篇
预防医学   394篇
眼科学   280篇
药学   967篇
中国医学   115篇
肿瘤学   530篇
  2023年   51篇
  2022年   127篇
  2021年   188篇
  2020年   111篇
  2019年   169篇
  2018年   222篇
  2017年   166篇
  2016年   251篇
  2015年   364篇
  2014年   424篇
  2013年   486篇
  2012年   694篇
  2011年   704篇
  2010年   536篇
  2009年   503篇
  2008年   520篇
  2007年   475篇
  2006年   473篇
  2005年   400篇
  2004年   315篇
  2003年   269篇
  2002年   267篇
  2001年   94篇
  2000年   83篇
  1999年   106篇
  1998年   113篇
  1997年   122篇
  1996年   136篇
  1995年   88篇
  1994年   82篇
  1993年   84篇
  1992年   71篇
  1991年   50篇
  1990年   59篇
  1989年   49篇
  1988年   42篇
  1987年   39篇
  1986年   35篇
  1985年   26篇
  1984年   24篇
  1983年   27篇
  1978年   26篇
  1977年   18篇
  1959年   23篇
  1958年   63篇
  1957年   61篇
  1956年   59篇
  1955年   52篇
  1954年   43篇
  1949年   26篇
排序方式: 共有9667条查询结果,搜索用时 15 毫秒
1.
Metformin, a drug for type 2 diabetes mellitus, has shown therapeutic effects for various cancers. However, it had no beneficial effects on the survival rate of human malignant mesothelioma (HMM) patients. The present study was performed to elucidate the underlying mechanism of metformin resistance in HMM cells. Glucose‐starved HMM cells had enhanced resistance to metformin, demonstrated by decreased apoptosis and autophagy and increased cell survival. These cells showed abnormalities in mitochondria, such as decreased ATP synthesis, morphological elongation, altered mitochondrial permeability transition pore and hyperpolarization of mitochondrial membrane potential (MMP). Intriguingly, Mdr1 was significantly upregulated in mitochondria but not in cell membrane. The upregulated mitochondrial Mdr1 was reversed by treatment with carbonyl cyanide m‐chlorophenyl hydrazone, an MMP depolarization inducer. Furthermore, apoptosis and autophagy were increased in multidrug resistance protein 1 knockout HMM cells cultured under glucose starvation with metformin treatment. The data suggest that mitochondrial Mdr1 plays a critical role in the chemoresistance to metformin in HMM cells, which could be a potential target for improving its therapeutic efficacy.  相似文献   
2.
3.
4.
Cytogenetic abnormalities are observed in approximately two‐thirds of patients with acute myeloid leukemia (AML). Chromosome rearrangements are associated with specific subtypes of AML and associated prognosis. We report a patient with AML, M2, who was primarily refractory to standard induction chemotherapy with idarubicin and cytarabine. Flow cytometry of a bone marrow aspirate showed aberrant expression of B‐cell markers including CD19. Cytogenetic studies disclosed a translocation between 5q35 and 11q13. Fluorescence in situ hybridization analyses demonstrated that neither the NSD1 nor MLL genes were involved in this case. Further study is required to define conclusively the genes involved and their contribution to pathogenesis in this case.  相似文献   
5.
Most ureteral tumors are transitional cell neoplasms. Neuroendocrine tumors of the genitourinary tract are extremely rare. To our knowledge, only one ureteral carcinoid tumor has been reported before. We report a second case of ureteral carcinoid tumor found in a 70-year-old female.  相似文献   
6.
Abstract  Gastrointestinal stromal tumor (GIST) is a recently described mesenchymal tumor that can develop in any portion of the gastrointestinal tract. The occurrence of a GIST in the urinary tract is rare, but GIST can present as tumor of the urinary tract or invade the urinary tract. This is the first reported case of GIST in the ileal neobladder, which presented as a submucosal tumor. The patient underwent an open exploration and partial resection of the neobladder pouch.  相似文献   
7.
The effect of haemodilution without volume expansion (isovolemic haemodilution) was assessed with respect to blood flow and oxygen transport across stenotic lesions of progressive severity in the dog carotid artery. As the mean haematocrit (Hct) was reduced from 40 +/- 1% (+/- SEM) to 32 +/- 0% (p less than 0.001), reductions in vascular resistance were significant across the 90% (p less than 0.001) and 95% (p less than 0.0003) relative carotid stenoses. Isovolemic haemodilution reduced fresh blood viscosity significantly by 27 +/- 3% (p less than 0.001) and 42 +/- 4% (p less than 0.001) at the low shear rates of 10 sec-1 and 1 sec-1 which are typical of low-flow states. Following a 20% reduction in Hct 30 to 35% increase (p less 0.001) in carotid blood flow occurred at non-critical degrees of stenosis while a mean 83% increase (p less than 0.001) occurred at the highly critical 95% relative stenosis. Oxygen transport after a 22% decrease in blood haemoglobin was significantly increased by 28% (p less than 0.01) at the 95% relative stenosis level. These data provide a physiologic rationale for the beneficial effects of haemodilution in acute cerebral ischaemia, cerebral vasospasm and cerebral revascularization or carotid endarterectomy.  相似文献   
8.
9.
The Australian government established the Council on Overseas Professional Qualifications (COPQ) in 1969. In response to approaches by the occupational therapy profession, an Expert Panel in Occupational Therapy was established in 1979 in order to develop a screening examination to be used in assessing the competency of overseas trained occupational therapists. This paper describes the development of the COPQ examination for all overseas qualified occupational therapists wishing to work in Australia; the experience of candidates since its inception in 1983; and the problems associated with achieving recognition of the COPQ examination throughout Australia given the lack of uniform recognition procedures in the various States and Territories. The need for a consistent national approach to the policy of recognition and employment of overseas trained occupational therapists is addressed, with stress placed on the need for all employer groups, in both the public and the private sectors, to cooperate with COPQ's assessment procedures.  相似文献   
10.
Summary. Twenty artificial periapical lesions confined to cancellous bone were prepared at the apices of first and second mandibular molars of human cadavers. The lesions emphasized removal of the lamina dura and preparation of a 'halo' lesion surrounding the root apex, plus the addition of a simulated sclerotic border. Radiographs taken before and after creation of the lesions were scored by three examiners for detectable lesions Cross-sections of the lesions were assessed for the extent of bone destruction. Periapical lesions confined to cancellous bone were detected in 80 per cent of cases, and the presence of a sclerotic border tended to enhance visualization, although not in all cases. Intentional cortical involvement also improved detection of lesions. The anatomical features of the periapical area appear to promote the visualization of lesions which might not be detected in other locations.  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