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   241篇
  免费   12篇
妇产科学   2篇
基础医学   35篇
口腔科学   5篇
临床医学   11篇
内科学   66篇
皮肤病学   1篇
神经病学   22篇
特种医学   9篇
外科学   67篇
综合类   2篇
一般理论   1篇
预防医学   11篇
眼科学   3篇
药学   10篇
中国医学   2篇
肿瘤学   6篇
  2022年   1篇
  2021年   6篇
  2020年   1篇
  2019年   5篇
  2018年   4篇
  2017年   7篇
  2016年   2篇
  2015年   5篇
  2014年   8篇
  2013年   10篇
  2012年   24篇
  2011年   22篇
  2010年   13篇
  2009年   10篇
  2008年   15篇
  2007年   15篇
  2006年   17篇
  2005年   21篇
  2004年   12篇
  2003年   8篇
  2002年   19篇
  2001年   3篇
  2000年   1篇
  1999年   2篇
  1998年   3篇
  1997年   2篇
  1996年   1篇
  1995年   2篇
  1994年   2篇
  1993年   1篇
  1992年   1篇
  1987年   2篇
  1986年   1篇
  1985年   2篇
  1984年   2篇
  1983年   2篇
  1982年   1篇
排序方式: 共有253条查询结果,搜索用时 15 毫秒
1.
Serum ALP may be a good indicator of Paget's disease in epidemiologic studies. Subjects with raised and normal ALP from a population cohort were matched (1 in 6, total 548), and radiographs were taken. ALP was an excellent marker of the disease (RR, 10.9), but the majority of those affected had normal ALP. INTRODUCTION: Evidence from radiographic surveys of limited skeletal sites has shown that Paget's disease of bone (PDB) is common in the elderly and has a distinct geographic variation. There is no information, however, about the relation of serum alkaline phosphatase (ALP) activity, a marker of the disease, and its prevalence in the population. MATERIALS AND METHODS: We analyzed data from a well-defined Dutch population cohort (the Rotterdam study) with the following specific aims: (1) to assess the relationship between serum ALP activity and prevalence of radiographically diagnosed PDB, (2) to estimate the overall prevalence of the disease in the Netherlands, and (3) to assess the appearance of the disease with time. Using a nested case-control design, subjects with an increased serum ALP and normal serum liver enzymes were matched for gender and age (1 to 6) with subjects with normal serum ALP activity. Radiographs of the thoracic and lumbar spine, pelvis, proximal femurs, knees, wrists, and hands were taken. RESULTS AND CONCLUSIONS: PDB was diagnosed in 20.5% of subjects with elevated serum ALP activity and in 2.3% in those with normal serum ALP activity, increasing with age in both groups. The relative risk (RR) for PDB in the presence of raised serum ALP activity was 10.9 (95% CI, 4.8, 24.9). The estimated prevalence of PDB in the population was 3.6%, and the large majority (about 86%) had normal serum ALP activity, contrasting findings in bone clinics where the opposite is the case. Finally, in subjects with normal and raised serum ALP activity but no PDB at baseline, radiographs taken 6-9 years later showed no evidence of the disease. This study demonstrated that serum ALP activity is a sensitive marker of PDB in men and women >55 years of age, but the majority of those affected have normal serum ALP activity.  相似文献   
2.
Spatial-temporal regulation of bone morphogenetic protein (BMP) and Wnt activity is essential for normal cardiovascular development, and altered activity of these growth factors causes maldevelopment of the cardiac outflow tract and great arteries. In the present study, we show that SOST, a Dan family member reported to antagonize BMP and Wnt activity, is expressed within the medial vessel wall of the great arteries containing smooth muscle cells. The ascending aorta, aortic arch, brachiocephalic artery, common carotids, and pulmonary trunk were all associated with SOST expressing smooth muscle cells, while the heart itself, including the valves, and more distal arteries, that is, pulmonary arteries, subclavian arteries, and descending aorta, were negative. SOST was expressed from embryonic day 15.5 up to the neonatal period. SOST expression, however, did not correspond with inhibition of Smad-dependent BMP activity or beta-catenin-dependent Wnt activity in the great arteries. Activity of both signaling pathways was already down-regulated before induction of SOST expression.  相似文献   
3.
Bisphosphonates are very effective treatments of postmenopausal osteoporosis. They suppress bone turnover, increase bone mineral density (BMD), and maintain or improve structural and material properties of bone, thereby decreasing the risk of fractures. All patients selected for treatment according to current international guidelines can benefit from bisphosphonate therapy independently of their prevalent rate of bone turnover. Long-term extensions (up to 10 years) of pivotal clinical trials with daily bisphosphonate administration showed sustained efficacy with no evidence of adverse effects on bone metabolism and skeletal fragility. Recent studies focus on the resolution of the effects of bisphosphonates on bone metabolism and fracture risk following cessation of long-term treatment. Such studies may help to formulate treatment recommendations according to the risk of the individual patient.  相似文献   
4.
OBJECTIVE: This study aimed at comparing three-dimensional (3-D) reconstruction with two-dimensional coronary angiograms with respect to anatomical parameters that might affect plaque formation and rupture. METHODS: Sixty patients with stable left anterior descending (LAD) lesions and 60 patients with an anteroseptal myocardial infarction and recanalized LAD were studied. RESULTS: Conventional angiography significantly underestimated the distance of the stenosis from the ostium of the LAD, 29.4+/-14.5 versus 35.3+/-18.5 mm, P<0.001. Vessel curvature at the site of the lesion was overestimated by conventional angiography compared with 3-D reconstruction, 147.6+/-30.6 degrees versus 162.3+/-11.2 degrees , P<0.001, as was axial bending of the LAD owing to ventricular contraction (17.8+/-7.78 degrees vs. 8.9+/-8.9 degrees , P<0.001). No agreement was observed between two-dimensional and 3-D analysis for either curvature on lesion or axial bending assessment, with intraclass correlation coefficient values 0.155 (-0.009, 0.315) and -0.022 (-0.183, 0.174), respectively. No significant agreement was found between the two methods in the detection of on-stenosis bifurcations (1.7%, kappa=0.086, P=0.349). CONCLUSION: Conventional coronary angiography cannot provide accurate estimates of anatomical parameters, such as distance of a coronary stenosis from the ostium of the vessel, coronary artery curvature at the site of stenosis, axial deformity and bending because of ventricular contraction, and classification of bifurcations. Reconstruction of the coronary tree in 3-D space is necessary for such estimations.  相似文献   
5.
Abstract. The development of pre-erythrocytic Plasmodium vivax vaccines is hindered by the lack of in vitro culture systems or experimental rodent models. To help bypass these roadblocks, we exploited the fact that naturally exposed Fy- individuals who lack the Duffy blood antigen (Fy) receptor are less likely to develop blood-stage infections; therefore, they preferentially develop immune responses to pre-erythrocytic-stage parasites, whereas Fy+ individuals experience both liver- and blood-stage infections and develop immune responses to both pre-erythrocytic and erythrocytic parasites. We screened 60 endemic sera from P. vivax-exposed Fy+ or Fy- donors against a protein microarray containing 91 P. vivax proteins with P. falciparum orthologs that were up-regulated in sporozoites. Antibodies against 10 P. vivax antigens were identified in sera from P. vivax-exposed individuals but not unexposed controls. This technology has promising implications in the discovery of potential vaccine candidates against P. vivax malaria.  相似文献   
6.
7.
BACKGROUND: Comparisons between segmental ostial disconnection of the pulmonary veins (PV) and circumferential ablation have produced conflicting results in patients with paroxysmal atrial fibrillation (AF). The aim of this study was to evaluate a staged ablation procedure, every step of which was assessed by means of AF inducibility. METHODS: Twenty-two patients with paroxysmal AF were subjected to three ablation stages during one session: (1) circumferential ablation around the PV ostia, (2) segmental ostial PV isolation, and (3) ablation of areas within the circumferential lines with fractionated electrograms or voltage >0.2 mV as well as linear ablation at the mitral isthmus and the left atrial roof. Endpoint of the procedure was noninducibility of AF at any stage. RESULTS: Average radiofrequency energy delivery, fluoroscopy, and procedure times were 43 +/- 11 minutes, 40 +/- 11 minutes, and 3.8 +/- 0.5 hours, respectively. At 6-months follow-up, four patients experienced recurrence of AF (18%), whereas two additional patients (9%) had left atrial arrhythmias not registered before the procedure. Ninety-five percent of the patients who did not have inducible AF (regardless of the stage of ablation at which noninducibility was achieved) were free of recurrent AF, as opposed to none of the patients in whom AF was inducible at the end of the procedure (log-rank test, P < 0.001). CONCLUSIONS: A staged ablation procedure combing circumferential and ostial PV ablation with AF noninducibilty as endpoint may result in high success rates without the need of prolonged ablation sessions in certain patients with paroxysmal atrial fibrillation.  相似文献   
8.
An open-porous protein sponge with mixed wettability is presented made entirely from whey proteins and with promising applications in biomedicine, pharmaceutical, and food industry. The fabrication relies on an additive-free, clean and scalable process consisting of foaming followed by controlled microwave-convection drying. Volumetric heating throughout the matrix induced by microwaves causes fast expansion and elongation of the foam bubbles, retards crust formation and promotes early protein denaturation. These effects counteract collapse and shrinkage typically encountered in convection drying of foams. The interplay of high protein content, tailored gas incorporation and controlled drying result in a dried structure with dual-scale porosity composed of open macroscopic elongated foam bubbles and microscopic pores in the surrounding solid lamellae induced by water evaporation. Due to the insolubility and mixed wettability of the denatured protein network, polar and non-polar liquids are rapidly absorbed into the interconnected capillary system of the sponge without disintegrating. While non-watery liquids penetrate the pores by capillary suction, water diffuses also into the stiff protein matrix, inducing swelling and softening. Consequently, the water-filled soft sponge can be emptied by compression and re-absorbs any wetting liquid into the free capillary space.  相似文献   
9.
10.
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