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   4037篇
  免费   226篇
  国内免费   18篇
耳鼻咽喉   59篇
儿科学   129篇
妇产科学   71篇
基础医学   582篇
口腔科学   87篇
临床医学   270篇
内科学   1014篇
皮肤病学   96篇
神经病学   295篇
特种医学   134篇
外科学   441篇
综合类   11篇
预防医学   194篇
眼科学   117篇
药学   308篇
中国医学   17篇
肿瘤学   456篇
  2023年   21篇
  2022年   14篇
  2021年   116篇
  2020年   69篇
  2019年   60篇
  2018年   91篇
  2017年   61篇
  2016年   86篇
  2015年   81篇
  2014年   142篇
  2013年   136篇
  2012年   233篇
  2011年   278篇
  2010年   162篇
  2009年   118篇
  2008年   247篇
  2007年   253篇
  2006年   255篇
  2005年   255篇
  2004年   254篇
  2003年   196篇
  2002年   186篇
  2001年   77篇
  2000年   67篇
  1999年   74篇
  1998年   45篇
  1997年   37篇
  1996年   34篇
  1995年   38篇
  1994年   32篇
  1993年   35篇
  1992年   49篇
  1991年   51篇
  1990年   50篇
  1989年   34篇
  1988年   41篇
  1987年   30篇
  1986年   33篇
  1985年   31篇
  1984年   22篇
  1983年   20篇
  1982年   13篇
  1980年   13篇
  1979年   17篇
  1978年   11篇
  1973年   11篇
  1969年   11篇
  1968年   10篇
  1967年   10篇
  1966年   11篇
排序方式: 共有4281条查询结果,搜索用时 78 毫秒
1.
2.
BACKGROUND: Psychotic symptoms in Alzheimer disease (AD+P) identify a heritable phenotype associated with more rapid cognitive decline. The authors have proposed that AD+P is itself a composite of a misidentification and a paranoid subtype with increased cognitive impairment restricted to the misidentification type. Most prior studies of the clinical correlates of AD+P have been limited, however, by the inclusion of prevalent cases. METHODS: Subjects with possible or probable AD or mild cognitive impairment (MCI) without psychosis at study entry were assessed at the time of initial presentation and then annually. Psychotic symptoms were assessed using the CERAD Behavioral Rating Scale. Survival analyses used Cox proportional hazard models with time-dependent covariates to examine the predictors of psychosis onset. RESULTS: A total of 288 subjects completed at least one follow-up examination. Mean duration of follow-up was 22.1 months. The incidence of psychosis was 0.19 per person-year. Cognitive impairment was associated with onset of psychosis, largely as a result of its association with onset of the misidentification, but not the paranoid, subtype. Including psychotropic medication use in the model revealed an association of antidepressant use with the onset of psychosis. This latter association appeared to arise from an underlying association between depression and the risk of psychosis onset rather than from antidepressant treatment. CONCLUSION: These findings are consistent with the hypothesis that the misidentification and the paranoid subtypes each define a more biologically homogeneous group than AD+P as a whole. Further exploration of the relationship between depressive symptoms and psychosis in patients with AD is warranted.  相似文献   
3.
Although there are effective antibacterial agents against plague, newer antibacterial agents have been developed which show more potent activity against other bacterial organisms, but have not been tested againstYersinia pestis. A strain ofYersinia pestis was selected (no. 22; National Institute of Infectious Diseases, Tokyo, Japan) that caused a systemic infection in mice.Y. pestis no. 22 was intraperitoneally inoculated into DDY-strain mice, and 13 oral or 6 injectable antibacterial drugs given to the infected mice at varying doses 1 and 24 hours after infection. Levofloxacin, sparfloxacin and ofloxacin were the most effective oral agents against the infection, and prulifloxacin and pazufloxacin were also effective but to a lesser extent. Also, gentamicin and arbekacin were the most potent injectable antibacterial agents againstY. pestis. These results suggest that there are several new drugs, both oral and injectable, which exert excellent in vivo antibacterial activity against a mouse infection model and may be useful for the clinical treatment of plague.  相似文献   
4.
5.
6.
7.
OBJECTIVE: To evaluate a proposed technique for the 3-dimensional (3D) detection of hemangiomas, including vascular malformation and their feeding arteries, in the head and neck. The new technique combines phase-contrast magnetic resonance angiography (PCMRA) without contrast medium and 3D fast asymmetric spin-echo (FASE) sequences. METHODS: The technique was applied to 3 patients having hemangiomas in the head and neck region. In 1 patient the image obtained with the proposed technique was compared to that obtained by standard contrast angiography. RESULTS: In all 3 patients, the 3D presence of the hemangiomas and the feeding arteries were well defined in images created by the proposed technique. Additionally, the characterization of the hemangioma's 3D structure and distribution of the feeding arteries coincided with those observed using contrast angiography in the case for which contrast angiography was also performed. CONCLUSIONS: Preliminary experience shows that the proposed technique combining 3D-FASE and 3D-PCMRA is useful to visualize both the 3D structure of hemangiomas and to identify the 3D distribution of the feeding arteries without using contrast medium.  相似文献   
8.
9.
A rare case of malignant peritoneal mesothelioma in a 49-year-old Japanese woman is presented. The tumor was limited to the peritoneum, and was cytologically and histologically identified as being composed of two components, epithelial and non-epithelial forms. The transition in her CA-125 level suggested that this tumor had good prospects of developing into a malignant mesothelioma. The good prognosis of the patient is considered to be attributed to detecting this tumor in its early stage and to aggressive chemotherapy.  相似文献   
10.
Serum lipid and apolipoprotein concentrations were measured in 37 male survivors of cerebral infarction (CI) and in 30 healthy controls. Both groups had similar total cholesterol levels, but the HDL-cholesterol level was significantly lower and the serum triglyceride level was significantly higher in the CI patients than in the controls. The ApoB level was significantly higher in the CI patients but there was no significant difference between the 2 groups in the levels of the other apolipoproteins (ApoA-I, A-II, C-II, C-III, and E). The HDL-cholesterol/ApoA-I ratio was significantly lower in the CI patients. Both the VLDL-triglyceride and VLDL-cholesterol levels were higher in the CI patients but the VLDL-cholesterol especially its cholesterol ester level was conspicuously high. A population of VLDL particles that bound to heparin on heparin-Sepharose columns was increased in the CI patients. We suggest that cholesterol ester is excessively transferred from HDL to VLDL during the disturbed catabolism of VLDL in CI patients.  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