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   3103篇
  免费   146篇
  国内免费   42篇
耳鼻咽喉   24篇
儿科学   45篇
妇产科学   19篇
基础医学   428篇
口腔科学   76篇
临床医学   196篇
内科学   789篇
皮肤病学   23篇
神经病学   293篇
特种医学   96篇
外科学   610篇
综合类   15篇
预防医学   64篇
眼科学   26篇
药学   259篇
中国医学   8篇
肿瘤学   320篇
  2023年   12篇
  2022年   39篇
  2021年   59篇
  2020年   38篇
  2019年   33篇
  2018年   48篇
  2017年   30篇
  2016年   63篇
  2015年   61篇
  2014年   63篇
  2013年   107篇
  2012年   167篇
  2011年   172篇
  2010年   98篇
  2009年   115篇
  2008年   152篇
  2007年   168篇
  2006年   176篇
  2005年   176篇
  2004年   193篇
  2003年   196篇
  2002年   178篇
  2001年   82篇
  2000年   56篇
  1999年   81篇
  1998年   42篇
  1997年   44篇
  1996年   41篇
  1995年   34篇
  1994年   37篇
  1993年   26篇
  1992年   54篇
  1991年   56篇
  1990年   54篇
  1989年   37篇
  1988年   34篇
  1987年   44篇
  1986年   31篇
  1985年   25篇
  1984年   32篇
  1983年   22篇
  1982年   12篇
  1981年   8篇
  1980年   11篇
  1979年   10篇
  1978年   8篇
  1976年   7篇
  1974年   9篇
  1971年   7篇
  1969年   6篇
排序方式: 共有3291条查询结果,搜索用时 15 毫秒
991.
992.
A 58-year-old woman underwent coronary angiography because of chest pain on exertion. Her three coronary arteries arose from separate ostia in the right sinus of Valsalva. The left anterior descending coronary artery coursed between the great vessels, and the circumflex coronary artery coursed anterior to the pulmonary artery. Angiographic and clinical data of this rare anomaly are described.  相似文献   
993.
Summary Cultured human lymphoblastoid B lymphocytes were surface-labelled with iodine125 and solubilized in 1% Triton X-100 in the presence of protease inhibitors. After purification of labelled glycoproteins by elution from immobilized wheat germ leetin with 0.3 mol/l N-acetyl-D-glucosamine, insulin receptors were quantitatively immunoprecipitated using IgG receptor auto-antibodies. The overall recovery of labelled glycoprotein was 0.02–0.04%; analysis by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and autoradiography under reducing conditions revealed two major bands with molecular weights of 126,000 and 90,000, and a minor band of 67,000 daltons. The mobilities of both major receptor subunits were increased after treatment with neuraminidase. When lymphocyte receptor binding was down-regulated before surface labelling, there was a concomitant decrease in the recovery of both the 126,000 and 90,000 subunits. These data indicate that down-regulation of binding probably involves degradation of the receptor molecule.  相似文献   
994.
A 67-year-old woman had been examined due to abnormalities on electrocardiography (ECG) at a medical checkup three years previously. When a negative T-wave was seen in leads I, aVL, and V1 to V4, but the abnormal findings were improved at consultation. Echocardiography revealed apical hypertrophy and hypertrophic nonobstructive cardiomyopathy was diagnosed. She felt chest discomfort in September, 2003 and an ECG showed a negative T-wave in leads I, II, III aVL, aVF and V2 to V6 and an elongation of QT interval Left ventriculography revealed myocardial hypertrophy at the left ventricular apex and left ventriclar wall motion was normal. Coronary angiography did not show any significant luminal narrowing. I-123 metaiodobenzyl-guanitidine scintigraphy showed marked perfusion defects at the left ventricular apex. After five months, ECG showed an improvement of the QT interval and a decrease in the negative T-wave. We considered that the repeated changes of ECG were caused by Takotsubo-type cardiomyopathy.  相似文献   
995.
Aims/hypothesis. The cumulative effects of several thrifty factors could contribute to the pathogenesis of Type II (non-insulin-dependent) diabetes mellitus. We screened the human UCP1 gene (UCP1) for polymorphisms associated with susceptibility to Type II diabetes. Methods. By using PCR and single-strand conformation polymorphism analysis, UCP1 were screened for mutations in 25 Type II diabetic subjects and 25 healthy control subjects. The allele frequencies of the detected polymorphisms were determined by PCR and restriction fragment length polymorphism analysis in 320 diabetic subjects and 250 control subjects. Results. An A→C transition in the 5' untranslated region (UTR) of exon 1 (112 bp upstream of the translation initiation codon) and a Met229→Leu variant were detected. The allele frequencies for the C variant and for the Leu229 variant were higher in the Type II diabetic group than in the control group (p = 0.017 and p = 0.038, respectively). These polymorphisms were in linkage disequilibrium (p < 0.00001). Luciferase assay showed that the former variant in the 5' UTR may affect the promoter activity of UCP1. Conclusion/interpretation. Both the A→C polymorphism and the Met229→Leu polymorphism of UCP1 are in linkage disequilibrium and could be one of the diabetes associated single nucleotide polymorphisms (SNPs). [Diabetologia (2001) 44: 373–376] Received: 24 August 2000 and in revised form: 17 November 2000  相似文献   
996.
We report a case of branchial cleft-like cysts (intrathyroidal lymphoepithelial cysts) associated with Hashimoto's thyroiditis. Palpation did not detect any nodules. Multiple cystic lesions were detected in the lateral side of the thyroid bilateral lobes by imagings of an I-123 scintigram, Tl-201 scintigram, sonography, and computerized tomography. Sonography displayed multiple cysts with strong echogenic spots in the cystic fluid. Repeated fine needle aspiration biopsies of the cysts consistently revealed only normal lymphocytes. Although these lesions could not be given diagnosis, subtotal thyroidectomy leaving the intact isthmus was performed. Microscopic findings revealed multiple branchial cleft-like cysts lined by flattened epithelial cells. Surrounding the epithelial lining were dense lymphoid follicles with large, reactive germinal centers. The remaining thyroid parenchyma showed Hashimoto's thyroiditis. Multiple branchial cleft-like cysts should be considered when sonographic examination reveals multiple cysts in the lateral side of the bilateral lobes, and fine needle aspiration biopsy displays only normal lymphocytes. To our knowledge, this is the first case of branchial cleft-like cysts associated with Hashimoto's thyroiditis reported in Japan.  相似文献   
997.
998.
Various cases of myelodysplastic syndrome (MDS) with diverse immunological disorders have been reported by many investigators. In this case report, we present a 70-year-old woman who had been diagnosed as having MDS and liver cirrhosis (LC) type C for 20 months, and who finally developed autoimmune phenomena against autologous blood cells. She was admitted to our hospital in order to evaluate her advanced anemia, thrombocytopenia and fatigue. The laboratory data at admission were as follows: hemoglobin 5.3 g/dl, red blood cell count 109 x 10(4)/microliter, white blood cell count 1,760/microliter, platelet count 4.3 x 10(4)/microliter and reticulocyte count 1.3%. The direct Coombs test was positive. In addition, anti-platelet antibody was positive, using the MPHA method. With these results, Evans syndrome secondary to MDS or LC was diagnosed. The mechanisms for the development of immunological disorders in patients with MDS or LC have not been fully elucidated. To our knowledge, this patient is one of the rare cases with MDS and Evans syndrome reported in the literature. During the generation process of autoantibodies, the role of HCV antigen in the pathogenesis of Evans syndrome was of interest in this patient.  相似文献   
999.

Background

Pteridines are metabolites of tetrahydrobiopterin, which serves as co-enzyme of nitric oxide synthase. We sought to investigate the usefulness of pteridines as biomarkers for childhood asthma control.

Methods

We conducted a single-center prospective cohort study involving 168 asthmatic children aged 4–17 years who visited the periodical asthma checkup program. Serum neopterin and biopterin levels were measured as pteridines at each visit along with measurement of FeNO, respiratory function tests, nasal eosinophil test, blood eosinophil count, and IgE level. We calculated coefficients for relation between pteridines and asthma control, which was assessed by questionnaires (JPAC: Japanese Pediatric Asthma Control Program).

Results

A total of 168 participants aged 10.3 ± 3.39 years (mean ± SD) with asthma were recruited. The participants in this study contained 58 patients (34.5%) of complete-controlled based on JPAC, 132 patients (76.0%) of well-controlled group based on GINA. FeNO and serum neopterin level did not correlate with following period's JPAC scores. In contrast, serum biopterin level significantly correlated with following period's JPAC total score (Coefficients 0.398; 95% CI 0.164 to 0.632; p value 0.001) and frequency of wheezing during exercise (Coefficients 0.272; 95% CI 0.217 to 0.328; p value < 0.001).

Conclusions

We found serum biopterin effected the following period's control status of asthmatic children, thus monitoring biopterin level will be a useful for management of asthma to adjust treatment.  相似文献   
1000.
BACKGROUND: Aortic regurgitation (AR) causes left ventricular (LV) volume overload, leading to progressive LV dilatation and dysfunction. In the present study it was examined whether blockade of angiotensin II type 1 receptor (AT1) could improve survival in cases of chronic severe AR. METHODS AND RESULTS: AR was induced by puncturing the aortic valves of wild-type (WT) and AT1a knockout (KO) mice. Mice that survived for 4 weeks after the operation were deemed to be a model of chronic severe AR and were followed up for 50 weeks (WT, n=29; KO, n=31). Baseline measurements made 4 weeks after surgery showed similar LV cavity and function in both genotypes. These conditions progressively worsened in both genotypes, but 16 weeks after baseline, KO mice showed significantly less LV dilatation, hypertrophy and interstitial fibrosis than WT mice. Cardiac mRNA expression of B-type natriuretic peptide and type I collagen was lower in KO than WT mice. The 50-week mortality rate was significantly lower among KO (45.2%) than WT (86.2%) mice, and postmortem findings indicated that the lower mortality was attributable to a lower incidence of congestive heart failure. CONCLUSIONS: In cases of chronic severe AR, blockade of AT1 attenuates the progression of LV dilatation, hypertrophy and fibrosis, thereby mitigating heart failure and improving long-term survival.  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