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   7254篇
  免费   429篇
  国内免费   31篇
耳鼻咽喉   81篇
儿科学   123篇
妇产科学   88篇
基础医学   900篇
口腔科学   214篇
临床医学   480篇
内科学   1784篇
皮肤病学   214篇
神经病学   507篇
特种医学   613篇
外科学   1019篇
综合类   59篇
预防医学   273篇
眼科学   314篇
药学   457篇
中国医学   26篇
肿瘤学   562篇
  2023年   37篇
  2022年   75篇
  2021年   112篇
  2020年   75篇
  2019年   92篇
  2018年   129篇
  2017年   104篇
  2016年   142篇
  2015年   158篇
  2014年   167篇
  2013年   210篇
  2012年   293篇
  2011年   304篇
  2010年   209篇
  2009年   162篇
  2008年   284篇
  2007年   332篇
  2006年   316篇
  2005年   348篇
  2004年   276篇
  2003年   317篇
  2002年   329篇
  2001年   327篇
  2000年   316篇
  1999年   259篇
  1998年   85篇
  1997年   75篇
  1996年   51篇
  1995年   47篇
  1994年   56篇
  1993年   44篇
  1992年   192篇
  1991年   161篇
  1990年   143篇
  1989年   154篇
  1988年   131篇
  1987年   146篇
  1986年   141篇
  1985年   146篇
  1984年   100篇
  1983年   72篇
  1982年   40篇
  1979年   65篇
  1978年   39篇
  1977年   35篇
  1976年   34篇
  1975年   43篇
  1971年   38篇
  1970年   37篇
  1969年   40篇
排序方式: 共有7714条查询结果,搜索用时 15 毫秒
61.
The hepatic arteries of 122 patients were analysed on angiography to identify the left medial segment of the liver. Left medial arterial branches were classified into three types: type I arising from the left hepatic artery on the umbilical portion of the portal vein; type II arising from proximal portion of left hepatic artery before reaching the umbilical portion of the portal vein; type III arising from right hepatic artery. Incidence of each type is 37.2%, 35.8% and 27.0%, respectively. The artery frequently kinks at the right side of the umbilical portion of the portal vein and a total of incidence is 68% and that of each type is 23.5%, 89.8% and 100%, respectively. We call this characteristic kinking point of the left medial arterial branches, the "M-point".  相似文献   
62.
Malnutrition is a core symptom of the frailty cycle in older adults. The purpose of this study was to investigate whether dysphagia influences nutrition or frailty status in community-dwelling older adults. The study participants were 320 Japanese community-dwelling older adults aged ≥65 years. All participants completed a questionnaire survey that included items on age, sex, family structure, self-rated health, nutritional and frailty status, and swallowing function. Nutritional status was categorized as malnourished, at risk of malnutrition, and well-nourished based on the Mini Nutrition Assessment-Short Form. The participants were then classified into a malnutrition (malnourished/at risk) or a well-nourished group (well-nourished). Frailty was assessed using the Cardiovascular Health Study criteria. The participants were then divided into a frailty (frail/pre-frail) or a non-frailty group (robust). Dysphagia was screened using the 10-item Eating Assessment Tool. Multiple logistic regression analysis was conducted to determine whether dysphagia was associated with nutritional or frailty status. The results revealed that dysphagia influenced both nutrition (odds ratio [OR]: 4.0; 95% confidence interval [CI]: 1.9–8.2) and frailty status (OR: 2.3; 95% CI: 1.0–5.2); therefore, the swallowing function would be an important factor for community-dwelling older adults on frailty prevention programs.  相似文献   
63.
Lasers in Medical Science - After publication of this paper, the authors determined an error in Fig. 1.  相似文献   
64.
The relationships between increases in body mass index (BMI) and increases in hypertension were compared between non-drinkers with elevated serum gamma-glutamyl transpeptidase (gamma-GTP) levels (> or = 50 U/l) and those with normal levels, who comprised 10,952 men and 22,107 women aged 40-59 years recruited from an occupational health clinic. Hypertension was found in 16.1% and 13.5% of the men and women, and elevated serum g-GTP was found in 10.8% and 2.8% of the men and women, respectively. The prevalences of hypertension and elevated serum gamma-GTP levels were both increased with increased BMI. Hypertension was, however, shown to be 1.5 times more prevalent in the persons with elevated serum gamma-GTP levels than in those with normal levels in both sexes, even after adjusting for BMI by a multiple logistic analysis. It can be concluded that elevations of serum gamma-GTP, which are probably a reflection of fatty liver in the non-drinkers, are closely related to the development of hypertension associated with increased obesity.  相似文献   
65.
A 6-year-old girl with post-hepatitic severe aplastic anaemia was referred to our hospital. Haematological examination showed a haemoglobin level of 5.2 g/dl, platelet count of 8,000/l, and white blood cell count of 130/l with 17% neutrophils. She was treated with recombinant human granulocytecolony stimulating factor (15 g/kg/day i.v.) and cyclosporin A (6 mg/kg/day p.o.). The absolute neutrophil count gradually increased, but Hb and platelets were not improved. The intravenous administration of recombinant human erythropoietin (100 U/kg three times a week) was started, and the reticulocyte count reached 20000/l on day 12. The platelets increased to 81000/l after 16 months of combined administration of recombinant human granulocyte-colony stimulating factor, recombinant human erythropoietin and cyclosporin A. After 20 months of combined administration, the haematological results were: Hb, 13.1 g/dl; platelets 80000/l: WBC, 9500/l with 40% neutrophils. After recombinant human granulocyte-colony stimulating factor treatment, the myeloid elements of the bone marrow and the number of granulocyte-macrophage colony forming units increased. Bone marrow erythropoiesis and erythroid colonies also increased after recombinant human erythropoietin administration. The clinical course suggested a beneficial effect of haemopoietic growth factors and cyclosporin A in post-hepatitic aplastic anaemia.  相似文献   
66.
In order to elucidate the cause of body weight loss in the early stage of tumor progression, morphological changes of striated muscle were investigated in rabbits every 10 days after VX2 carcinoma implantation. The lean body mass started to decrease in the tumor-bearing rabbits 10 days after implantation, and body fat ratio showed a significant decrease from 30 days, different from the starved rabbits, whose lean body mass and body fat ratio started to decrease from 10 days. Morphological hallmarks of apoptosis in muscle cells were detected in tumor-bearing animals prior to the tumor growth but not in starved animals. These findings suggest that muscle cell apoptosis may be responsible for the body weight loss in the early tumor-bearing.  相似文献   
67.
OBJECTIVE: The purpose of this study is to show and analyze the CT appearance of pseudolesions of the liver caused by rib compression and to discuss the possible mechanism on the basis of findings of incremental dynamic CT, CT during arterial portography, and CT hepatic arteriography. CONCLUSION: Focal compression of the liver caused by curved ribs can cause transient focal diminishment of portal venous perfusion without significantly altering hepatic arterial perfusion. Such diminishment may be observed as low-density areas on the early phase of incremental dynamic CT.  相似文献   
68.
OBJECTIVES: To establish the source of metallic artifacts on postoperative MRI of the temporomandibular joint after arthroplasty. METHODS: An experiment was carried out to evaluate MR artifacts which were thought to have been caused by minute metallic particles deposited at surgery. Four types of cutting instruments were used to cut an extracted tooth: a diamond bur attached to a dental air turbine handpiece, a steel bur and bone bur attached to a dental micromotor handpiece and a bone file. The tooth fragments were collected in plastic centrifuge tubes in water. These samples were evaluated with six MR sequences. RESULTS: MR artifacts were clearly demonstrated in samples using the bone bur and the bone file but not the diamond and steel burs. CONCLUSIONS: The artifacts seen on postoperative MRI were derived from minute metal particles from the bone bur or file used for condylar arthroplasty. Metal artifacts should be considered when interpreting postoperative MR images.  相似文献   
69.
We present two cases of hepatic angiomyolipoma in which the size and internal composition of the tumor changed during the course of follow-up study. The tissue elements composing the tumor are thought to grow or regress independently during the disease's clinical course. Radiologists should be aware that hepatic angiomyolipoma can change in size and internal composition during its natural course.  相似文献   
70.
We attempted to determine whether cytoplasmic fat in clear cell renal cell carcinoma (RCC) can be identified by chemical shift gradient-echo magnetic resonance imaging (CSI). CSI was performed for 22 clear cell RCCs and 30 other renal tumors (including 16 non-clear cell RCCs), all of which were surgically proven. Signal reduction in out-of-phase images of these tumors was retrospectively evaluated and compared. The signal loss ratio (SLR) was defined and calculated. Fat staining of specimens from 16 tumors was performed and correlated with SLR. SLR was significantly higher in clear cell RCCs than in non-clear cell RCCs (P < 0.001). There was a significant correlation between degree of fat staining positivity of the specimens and SLR (P < 0.01). When signal reduction in out-of-phase images suggested the diagnosis of clear cell RCC, correct diagnosis of this entity was made in resected renal tumors with sensitivity, specificity, and accuracy of 82%, 90%, and 87%, respectively. CSI can demonstrate cytoplasmic fat in clear cell RCCs, which helps to differentiate this entity from other RCCs.  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