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   1004篇
  免费   79篇
  国内免费   16篇
耳鼻咽喉   5篇
儿科学   62篇
妇产科学   14篇
基础医学   147篇
口腔科学   34篇
临床医学   132篇
内科学   226篇
皮肤病学   34篇
神经病学   40篇
特种医学   138篇
外科学   65篇
综合类   41篇
预防医学   76篇
眼科学   6篇
药学   45篇
中国医学   2篇
肿瘤学   32篇
  2023年   7篇
  2022年   9篇
  2021年   20篇
  2020年   17篇
  2019年   22篇
  2018年   18篇
  2017年   23篇
  2016年   24篇
  2015年   27篇
  2014年   34篇
  2013年   43篇
  2012年   28篇
  2011年   30篇
  2010年   58篇
  2009年   47篇
  2008年   30篇
  2007年   43篇
  2006年   29篇
  2005年   28篇
  2004年   16篇
  2003年   19篇
  2002年   17篇
  2001年   12篇
  2000年   15篇
  1999年   16篇
  1998年   51篇
  1997年   39篇
  1996年   37篇
  1995年   26篇
  1994年   35篇
  1993年   29篇
  1992年   16篇
  1991年   16篇
  1990年   8篇
  1989年   25篇
  1988年   23篇
  1987年   18篇
  1986年   12篇
  1985年   11篇
  1984年   8篇
  1983年   13篇
  1982年   13篇
  1981年   10篇
  1980年   16篇
  1978年   5篇
  1977年   14篇
  1976年   9篇
  1975年   7篇
  1970年   4篇
  1956年   3篇
排序方式: 共有1099条查询结果,搜索用时 15 毫秒
81.
Original Gianturco expandable stents and their modifications were used to create an experimental intrahepatic portacaval anastomosis (EIPCA) in 30 young domestic swine without portal hypertension. The study focused on the design of a suitable stent, the technique of its application, and the evaluation of short-term patency of the EIPCA. A stent with a 2.5-cm-long body and wire skirts on both ends was most suitable for EIPCA creation. Well-positioned stents shunted most of the portal blood in the inferior vena cava circulation and remained patent for 4-6 weeks. Ingrowth of liver parenchyma and abundant proliferation of the intima and connective tissue inside the stent lumen in these rapidly growing animals gradually decreased EIPCA patency, and thrombus formation with diminished blood flow closed them completely.  相似文献   
82.
Transient synovitis of the hip in children: role of US   总被引:7,自引:0,他引:7  
Transient synovitis of the hip remains a common diagnostic problem for the clinician. The physical signs are not pathognomonic of the condition, and the classic technical examinations are of little help. Therefore, the authors retrospectively studied the value of hip arthrosonography in 46 children with clinical symptoms suggesting pathologic hip conditions. In 20 of the 21 patients with a final diagnosis of transient synovitis, articular effusion was detected on ultrasound (US). Conventional radiography showed an increased medial joint space in only eight of these patients. Increased echogenicity of the articular fluid was found in both transient synovitis and septic arthritis. The high sensitivity of US in detecting intraarticular fluid was demonstrated by cadaver studies.  相似文献   
83.
Wilms  GE; Baert  AL; Staessen  JA; Amery  AK 《Radiology》1986,160(3):713-715
The ability of diagnostic intravenous digital subtraction angiography (IVDSA) to demonstrate the degree of renal artery stenosis was compared with that of intraarterial angiography in 45 patients with 92 arteries. Stenotic lesions on both IVDSA and intraarterial studies were classified as normal (0% stenosis), minor (less than 50%), low grade (50%-80%), and high grade (80%-99%). There was agreement about the degree of stenosis in 90% of the cases. IVDSA grading was correct in 94% of atheromatous lesions and in 56% of the fibromuscular dysplastic lesions. In the high-grade atheromatous lesions, the degree of stenosis was slightly overestimated on IVDSA studies in 22.5% of the cases. In fibromuscular dysplasia, stenosis was underestimated in 33% of the cases.  相似文献   
84.
Occult fractures of the proximal femur: MR imaging   总被引:9,自引:0,他引:9  
Deutsch  AL; Mink  JH; Waxman  AD 《Radiology》1989,170(1):113
  相似文献   
85.
B-lymphocytes obtained from patients with either rheumatic feveror rheumatic heart disease and from normal subjects were reactedwith serum obtained from rabbits immunized with streptococcalcell wall antigen. The presence of cytotoxicity was sought usingan inverted phase microscope after differential uptake of eosindye. The serum was found to be significantly more cytotoxicto HLA-DR4 containing cells of both patients and normals comparedwith DR4 negative cells (P<0. 0001). KEY WORDS: Streptococcal cell wall antigen, Antiserum, Cytotoxicity  相似文献   
86.
OBJECTIVE: To elicit from individuals in a population their current weight and height, weight goals, and weight control strategies to aid in design of effective interventions to prevent and treat obesity. SUBJECTS AND METHODS: By random digit dial telephone survey, 1224 adult residents of Olmsted County, Minnesota, were contacted between February 28 and May 5, 2000. They self-reported weights and weight goals and described physical characteristics associated with their desire to lose weight. RESULTS: Among the 1224 respondents, 65.6% of men and 47.9% of women reported that they were overweight (body mass index [BMI], 25.0-29.9 kg/m2) or obese (BMI, > or =30.0 kg/m2). Only 0.4% of men and 3.7% of women reported that they were underweight (BMI, <18.5 kg/m2). Of the respondents 72.6% of men and 85.1% of women reported that they were either trying to lose or not gain weight. The average weight loss goal for individuals trying to lose weight was 23.4 pounds for men and 28.0 pounds for women. Only one third of individuals trying to lose weight and one fifth of individuals trying not to gain weight reported using the recommended approach of combining energy restriction with at least 150 minutes of exercise per week. CONCLUSIONS: The prevalence of overweight and obesity in the population and the underutilization of combining both restricting energy intake and exercising at least 150 minutes per week for weight control is high. Like the majority of people in the United States, the majority of people in Olmsted County desire to control their weight. The community has responded with plans to help residents meet their goals, although efficacy and outcomes remain to be determined.  相似文献   
87.
88.
Because DXA is a projection technique, anterior–posterior (AP) measurements of the spine include the posterior elements and the vertebral body. This may be a disadvantage because the posterior elements likely contribute little to vertebral fracture resistance. This study used QCT to quantify the impact of the posterior elements in DXA AP spine measures. We examined 574 subjects (294 females and 280 males), age 6–25 yr, with DXA and QCT. QCT measures were calculated for the cancellous bone region and for the vertebral body including and excluding the posterior elements. DXA data were analyzed for the entire L3 vertebra and for a 10‐mm slice corresponding to the QCT scan region. BMC and BMD were determined and compared using Pearson's correlation. The posterior elements accounted for 51.4 ± 4.2% of the total BMC, with a significant difference between males (49.9 ± 4.0%) and females (52.8 ± 3.9%, p < 0.001). This percentage increased with age in younger subjects of both sexes (p < 0.001) but was relatively consistent after age 17 for males and 16 for females (p > 0.10). DXA areal BMD and QCT volumetric BMD correlated strongly for the whole vertebra including the posterior elements (R = 0.83), with BMC measures showing a stronger relationship (R = 0.93). Relationships were weaker when excluding the posterior elements. We conclude that DXA BMC provides a measure of bone that is most consistent with QCT and that the contribution of the posterior elements is consistent in young subjects after sexual maturity.  相似文献   
89.

Background and purpose:

Statins and fibrates can produce mild to life-threatening skeletal muscle damage. Resting chloride channel conductance (gCl), carried by the ClC-1 channel, is reduced in muscles of rats chronically treated with fluvastatin, atorvastatin or fenofibrate, along with increased resting cytosolic calcium in statin-treated rats. A high gCl, controlled by the Ca2+-dependent protein kinase C (PKC), maintains sarcolemma electrical stability and its reduction alters muscle function. Here, we investigated how statins and fenofibrate impaired gCl.

Experimental approach:

In rats treated with fluvastatin, atorvastatin or fenofibrate, we examined the involvement of PKC in gCl reduction by the two intracellular microelectrodes technique and ClC-1 mRNA level by quantitative real time-polymerase chain reaction. Direct drug effects were tested by patch clamp analysis on human ClC-1 channels expressed in human embryonic kidney (HEK) 293 cells.

Key results:

Chelerythrine, a PKC inhibitor, applied in vitro on muscle dissected from atorvastatin-treated rats fully restored gCl, suggesting the involvement of this enzyme in statin action. Chelerythrine partially restored gCl in muscles from fluvastatin-treated rats but not in those from fenofibrate-treated rats, implying additional mechanisms for gCl impairment. Accordingly, a decrease of ClC-1 channel mRNA was found in both fluvastatin-and fenofibrate-treated rat muscles. Fenofibric acid, the in vivo metabolite of fenofibrate, but not fluvastatin, rapidly reduced chloride currents in HEK 293 cells.

Conclusions and implications:

Our data suggest multiple mechanisms underlie the effect of statins and fenofibrate on ClC-1 channel conductance. While statins promote Ca2+-mediated PKC activation, fenofibrate directly inhibits ClC-1 channels and both fluvastatin and fenofibrate impair expression of mRNA for ClC-1.  相似文献   
90.
Bioresorbable scaffolds (BRS) have been advocated as the fourth revolution in interventional cardiology medical devices with promising technology to improve the treatment of coronary artery disease with an event-free future. We describe the first reported use and early collapse of the Magmaris® Resorbable Magnesium Scaffold (RMS) stent (BIOTRONIK AG, Switzerland) to relieve left pulmonary artery severe stenosis in a newborn after the Norwood procedure. The stent collapse was detected 2 weeks after implantation and urgently treated with a balloon-expandable stent. This complication raises the alarm about the need to keep implanted RMS under scrutiny. The possibility of faster scaffold resorption in small babies or lack of sufficient radial force of RMS to resist acute vessel recoil has led to ineffective relief of branch pulmonary artery stenosis and failure to enable a safe short-term bridge to Stage II palliation.  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