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   1396篇
  免费   62篇
  国内免费   19篇
耳鼻咽喉   9篇
儿科学   79篇
妇产科学   12篇
基础医学   172篇
口腔科学   50篇
临床医学   109篇
内科学   262篇
皮肤病学   34篇
神经病学   63篇
特种医学   125篇
外科学   156篇
综合类   121篇
预防医学   74篇
眼科学   32篇
药学   129篇
中国医学   6篇
肿瘤学   44篇
  2023年   5篇
  2022年   13篇
  2021年   31篇
  2020年   9篇
  2019年   16篇
  2018年   27篇
  2017年   25篇
  2016年   25篇
  2015年   34篇
  2014年   52篇
  2013年   53篇
  2012年   91篇
  2011年   63篇
  2010年   72篇
  2009年   57篇
  2008年   82篇
  2007年   74篇
  2006年   57篇
  2005年   56篇
  2004年   42篇
  2003年   41篇
  2002年   56篇
  2001年   23篇
  2000年   13篇
  1999年   24篇
  1998年   55篇
  1997年   44篇
  1996年   34篇
  1995年   24篇
  1994年   30篇
  1993年   28篇
  1992年   13篇
  1991年   10篇
  1990年   10篇
  1989年   16篇
  1988年   15篇
  1987年   28篇
  1986年   11篇
  1985年   14篇
  1984年   7篇
  1983年   10篇
  1982年   16篇
  1981年   9篇
  1980年   7篇
  1978年   12篇
  1977年   6篇
  1976年   10篇
  1975年   5篇
  1974年   3篇
  1963年   4篇
排序方式: 共有1477条查询结果,搜索用时 15 毫秒
101.
Mark  AS; Hricak  H 《Radiology》1987,162(2):311-314
To assess the safety of magnetic resonance (MR) imaging in women who have an intrauterine contraceptive device (IUD) in place, in vitro and in vivo studies were performed at both 0.35 and 1.5 T. Two commonly used IUDs were tested, one all of plastic, the other with a coil of copper wire on it. Specifically, the study assessed possible motion of the IUD in the magnetic field, potential of the IUD to heat up during two spin-echo imaging sequences commonly used in MR imaging of the pelvis (2,000/30 and 60 [repetition time, msec/echo time, msec], and 500/30), and the appearance on MR images of the IUD devices. A retrospective review of MR images of the pelvis in six women who had an IUD in place was also performed. Results show that an IUD does not move under the influence of the magnetic field, does not heat during spin-echo sequences commonly used for pelvic imaging, and does not produce artifacts in vitro or in vivo. Patients with either type of IUD can be safely imaged with MR, and MR images of the pelvis are not degraded by the presence of an IUD.  相似文献   
102.
Lymphoceles: imaging characteristics and percutaneous management   总被引:3,自引:0,他引:3  
Twenty-five patients who had lymphoceles underwent sectional imaging and interventional radiologic procedures. Viewed using sonography, lymphoceles were hypoechoic to anechoic, occasionally with internal septa and debris. Low numbers (occasionally negative values) were observed using computed tomography (CT); these numbers strongly suggest the diagnosis of lymphocele. Calcification was observed on CT images of one patient. Diagnostic aspiration revealed tan to yellow fluid containing many lymphocytes; pathognomonic fat globules were observed in four cases. Malignant cells were found in two collections, an unusual occurrence. Therapeutic needle aspiration and short-term catheter drainage were usually unsuccessful (only one of five patients [20%] was cured). Long-term (1-5-week) catheter drainage cured 11 of 14 patients (78.6%). Sclerosing agents may have been beneficial for lymphocele obliteration in three of four patients. For most patients, lymphoceles may be diagnosed and treated successfully using radiologic means.  相似文献   
103.
The Concorde trial compared immediate (Imm) with deferred (Def) AZT monotherapy in asymptomatic HIV-positive participants. Haematological and immunological markers and weight were measured throughout, and correlated with clinical endpoints. Markers associated with disease progression (CD4 lymphocyte count and percentage, platelets, p24 antigen and beta 2 microglobulin favoured Imm: those associated with toxicity (haemoglobin, neutrophils and white cell count) favoured Def. CD8 and total lymphocyte count did not differ significantly between groups. In multivariate analysis, the combination of baseline CD4, p24 antigen and beta 2m was the best baseline predictor of disease. Including change in CD4 and beta 2m at 12 weeks, or changes over follow- up in these markers significantly improved the fit. Markers were also incorporated into the definition of 'clinical' endpoints. Hazard ratio estimates from end-points that included CD4 < 50 and CD4 < 25 were closest to those for AIDS or death alone, but added very few extra events. Use of other landmark CD4 counts (100 or greater) or relative decreases in counts (25% or more) increased the number of events, but overestimated the effect of immediate AZT. Although AZT had a beneficial effect on the surrogate markers of efficacy evaluated, these changes did not predict clinical outcome, nor could the markers be usefully incorporated into an endpoint definition.   相似文献   
104.
105.
106.
Lipid targets can be difficult to attain in familial hypercholesterolaemia. To compare atorvastatin with simvastatin- fenofibrate and simvastatin-cholestyramine therapy, we studied 54 patients with familial hypercholesterolaemia over periods of 2-6 months on each therapeutic regimen. The atorvastatin regimen reduced total cholesterol by 41.2 +/- 11.2%, LDL by 45.6 +/- 15.5%, triglycerides by 33.8 +/- 24.8%, and increased HDL by 2.3 +/- 37.0%. Simvastatin- fenofibrate therapy achieved reductions of 33.9 +/- 8.5% in cholesterol, 42.0 +/- 12.2% in LDL, 34.7 +/- 38.3% for triglycerides, and a 25.4 +/- 55.1% increase in HDL. Simvastatin-cholestyramine gave a reduction of 31.3 +/- 11.8% in cholesterol, 36.0 +/- 14.4% in LDL, 13.7 +/- 36.3% in triglycerides, and a 1.1 +/- 30.3% rise in HDL. The atorvastatin regimen was marginally but not significantly better than simvastatin-fenofibrate in improving the LDL:HDL ratio, LDL:apoB and and apolipoprotein B:A1 ratios. Eleven patients (20.4%) had side- effects: two discontinued atorvastatin due to side-effects; two patients had rashes; six had myalgia and two had diarrhoea. Gastrointestinal side-effects were described in 16 (30.1%) patients on simvastatin-cholestyramine therapy and four cases of myalgia (11.2%) were seen with simvastatin-fenofibrate. In nine patients on atorvastatin (20.4%) a 30% or greater fall in HDL was observed, compared to five patients with resin therapy (9.2%) and two with fibrate therapy (5.5%). There were no significant differences in liver or muscle biochemistry between the regimens, but atorvastatin did raise transaminase and creatine kinase concentrations significantly compared to pre-treatment values (p = 0.001). Atorvastatin significantly improves the lipid profile in most patients compared with other regimens. It has a comparable incidence of side-effects to combination therapy regimens.   相似文献   
107.
The mouse monoclonal antibody M2A1 of IgG1 class, which is highly specific for blood group M antigen, was obtained and characterized by means of hemagglutination, enzyme-linked immunosorbent assay, immunoblotting, and inhibition assays. The use of modified M glycoprotein preparations for inhibition tests and of variant McN and Henshaw red cell membranes for immunoblotting showed that M2A1 recognized an epitope including the NH2-terminal serine and sialic acid residues of glycophorin A, whereas the fifth glycine residue was not involved. The reactivity of the antibody with M antigen was distinctly dependent on ionic strength and pH; the optimum was at pH 8 to 9. The alpha-amino group of terminal serine residue was not necessary for the reaction with M2A1 antibody, and the results obtained suggested that the positive charge of this group contributed to decreasing antigen-antibody reactions at pH below 8. The reaction of the antibody with blood group N antigen was not detectable in any of the assays used.  相似文献   
108.
This study was designed to examine the "true sensitivity" of a specific head-up tilt (HUT) testing protocol using clinical findings. The HUT protocol used 45 minutes at 60 degrees for the baseline portion and intermittent boluses of 2, 4, and 6 micrograms of isoproterenol in the second phase. Eighty-eight patients (40 men and 48 women; mean age of 33.8 +/- 16 years) with recurrent syncope and high pretest likelihood of neurally mediated syncope were included. The following were considerated as high pretest likelihood criteria: (1) at least two syncopal episodes; (2) no structural heart disease and normal baseline ECG; (3) age < 65 years; (4) a typical history of neurally mediated syncope, triggering factors plus premonitory signs; and (5) short duration of symptoms and fast recovery without neurological sequelae. Fifty-four patients (61%) had a positive tilt test (34/88 baseline [39%] and 20/50 with isoproterenol [40%]). The shorter time interval between the last syncopal episode and baseline HUT test was the only predictor for a positive response (P < 0.003). Conversely, this time interval was not predictor of positive responses during isoproterenol-tilt testing. In conclusion: (1) we claim a "sensitivity" for this combined protocol of 61%; and (2) our results indicate that patients with syncope of unknown origin must be tilted nearest as possible to the last syncope to increase the positive responses of HUT test.  相似文献   
109.
Laparoscopic cholecystectomy is the standard procedure for symptomatic gall stone disease. Situs inversus is a condition where the visceral anatomy is reversed. Laparoscopic cholecystectomy in a patient of situs inversus is a technically difficult procedure. Six patients of situs inversus underwent laparoscopic cholecystectomy from January 2003 to December 2009. In the first patient of situs inversus, we operated by placing the ports in mirror image fashion as that of standard laparoscopic cholecystectomy. However in next five patients we modified the technique by interchanging the epigastric and left mid clavicular line ports to overcome the problem of handedness. The procedure was successfully completed in all six patients. No intraoperative or postoperative complications occurred. The mean operating time was 65 mins (45–85 mins). Laparoscopic cholecystectomy is safe in patients of situs inversus. However, extreme care and skill is required to identify the reversed anatomy and to overcome the problem of handedness. Interchanging the epigastric and left mid clavicular line ports makes the procedure easier.  相似文献   
110.

Background  

Liver injury due to dengue viral infection is not uncommon. Acute liver injury is a severe complicating factor in dengue, predisposing to life-threatening hemorrhage, Disseminated Intravascular Coagulation (DIC) and encephalopathy. Therefore we sought to determine the frequency of hepatitis in dengue infection and to compare the outcome (length of stay, in hospital mortality, complications) between patients of Dengue who have mild/moderate (ALT 23-300 IU/L) v/s severe acute hepatitis (ALT > 300 IU/L).  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