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   12524篇
  免费   768篇
  国内免费   289篇
耳鼻咽喉   1483篇
儿科学   265篇
妇产科学   146篇
基础医学   772篇
口腔科学   163篇
临床医学   2600篇
内科学   1110篇
皮肤病学   83篇
神经病学   346篇
特种医学   1900篇
外科学   623篇
综合类   1309篇
现状与发展   2篇
一般理论   4篇
预防医学   1159篇
眼科学   531篇
药学   698篇
  9篇
中国医学   155篇
肿瘤学   223篇
  2024年   12篇
  2023年   150篇
  2022年   211篇
  2021年   523篇
  2020年   447篇
  2019年   430篇
  2018年   451篇
  2017年   402篇
  2016年   501篇
  2015年   447篇
  2014年   881篇
  2013年   899篇
  2012年   694篇
  2011年   707篇
  2010年   654篇
  2009年   645篇
  2008年   633篇
  2007年   677篇
  2006年   613篇
  2005年   471篇
  2004年   374篇
  2003年   345篇
  2002年   248篇
  2001年   279篇
  2000年   200篇
  1999年   198篇
  1998年   149篇
  1997年   146篇
  1996年   123篇
  1995年   106篇
  1994年   142篇
  1993年   83篇
  1992年   83篇
  1991年   59篇
  1990年   69篇
  1989年   48篇
  1988年   48篇
  1987年   32篇
  1986年   43篇
  1985年   63篇
  1984年   73篇
  1983年   40篇
  1982年   56篇
  1981年   25篇
  1980年   19篇
  1979年   23篇
  1978年   23篇
  1977年   11篇
  1976年   9篇
  1975年   7篇
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
21.
Objective: To investigate the ability of contrast enhancement patterns of contrast-enhanced ultrasound in differentiating benign and malignant soft tissue tumours.  相似文献   
22.
The availability of human papillomavirus (HPV) vaccines and screening tests has raised the possibility of globally eliminating cervical cancer, which is caused by HPV. Cervical cancer is a very common malignancy worldwide, especially among deprived women. High vaccination coverage is key to the containment and eventual elimination of the infection. Public HPV vaccination programmes in Italy and Denmark were swiftly established and are among the most successful worldwide. Still, in both countries, it has been challenging to achieve and maintain the recommended coverage of > 80% in girls. In a well‐studied Italian region, vaccination coverage in girls at age 15 years (World Health Organization''s gold standard) reached 76% in 2015 but decreased to 69% in 2018, likely due to work overload in public immunization centres. In Denmark, doubts about safety and efficacy of the HPV vaccine generated a decline in coverage among girls age 12–17, from 80% in 2013 down to 37% in 2015, when remedial actions made it rise again. Insights from these two countries are shared to illustrate the importance of monitoring coverage in a digital vaccine registry and promptly reacting to misinformation about vaccination.

Abbreviations

CC
cervical cancer
FVG
Friuli Venezia Giulia
HICs
high‐income countries
HPV
human papillomavirus
LMICs
middle‐income countries
WHO
World Health Organization
  相似文献   
23.
Transforaminal injections are sometimes used for the diagnosis and treatment of painful conditions in the lumbar and to a lesser degree in the cervical spine. The technique is most often used when investigating/treating radiculopathy caused by degenerative disease. But how selective are the nerve root blocks? What possible structures other than the intended nerve root are affected from such injections? This study was undertaken in order to try to answer these questions, as no study focusing on the possible spread from the transforaminal selective nerve root blocks in the cervical spine has been performed earlier. In three groups of patients, each group including three patients, we injected three different volumes (0.6, 1.1 and 1.7 ml) with a transforaminal technique in the cervical spine. In all the injections, a small amount of contrast media was added. The spread of the injections were then investigated using multi-slice computed tomography with reconstructions. The imaging revealed a possible effect on other nerve roots than the intended ones when a larger volume was used for the root blocks. The spread was related to the injected volume as well as to local anatomy (size of foraminal area). In this study, only 0.6-ml injections could be accepted for being selective enough for diagnostic investigations.  相似文献   
24.
Enhanced and non-enhanced computed tomography (CT) brain scans were performed within 72 h of surgery on 21 children in whom brain tumors had been resected totally or subtotally, and scans were repeated at varying intervals thereafter. Biopsies of the resection margins were performed in 12 patients at the end of the surgical procedure. The immediate CT scan showed enhancement in the resection margin in 13 of the 21 patients and in 9 of the 13, the enhancement disappeared on follow-up scans. There was discordance between the results of immediate CT scan examination and the biopsies of the resection margins in 7 of the 12 cases. The advantages and disadvantages of an immediate postoperative scan versus a more delayed CT scan are discussed.  相似文献   
25.
Summary In 1981 generalized anaphylaxis was registered on 166 occasions in Dutch general and academic hospitals. Clinical details of 120 of those patients revealed that in 107 anaphylaxis was either probable (n=90) or possible (n=17), whereas in 13 cases some other reaction than anaphylaxis had occurred. The series of confirmed cases contained 46 men and 61 women, with mean ages of 47 y and 48 y, respectively.There was a complete recovery in 102 patients and two patients died. Hypotension was present in 79 cases (74%), dyspnoea in 34 cases (32%) and a skin reaction, mainly urticaria, erythema or angioedema, was mentioned in 62 cases (58%). Most cases of anaphylaxis were drug-induced (76%), the main causes being the analgesic glafenine and contrast media. Glafenine was mentioned as the cause in 36% of all admissions for drug-induced anaphylaxis. Only 3.7% of cases had been reported to the voluntary reporting scheme of the Netherlands Centre for Monitoring of Adverse Reactions to Drugs.On the basis of reimbursement data, the risk of developing severe anaphylaxis to glafenine was estimated at 11.7–19.3-fold relative to indomethacin, and 13.4–20.2-fold relative to oral penicillins.  相似文献   
26.
BACKGROUND: Visual motion processing is compromised in schizophrenia, as shown in deficient velocity discrimination. Processing of motion signals comprises progressive stages along the geniculate-striate-extrastriate-cortex pathway. Based on neurophysiologic and brain lesion studies, a velocity discrimination deficit can implicate early-stage motion processing if it is contrast-dependent or late-stage motion processing if it is contrast-independent. METHODS: To determine which stage underlies the deficient velocity discrimination in schizophrenia, we examined the effects of visual contrast on velocity discrimination. We measured velocity discrimination thresholds in schizophrenia patients (n = 34) and normal control subjects (n = 17) at both low and high contrasts, using each subject's contrast detection threshold to equate contrast levels. RESULTS: Schizophrenia patients showed poor velocity discrimination that improved little with high contrast, whereas normal control subjects showed enhanced velocity discrimination with increased contrast. CONCLUSIONS: The finding that the velocity discrimination deficit in schizophrenia is independent of contrast modulation implicates the later, rather than the earlier, stages of motion processing, which is mediated in the extrastriate cortex.  相似文献   
27.
目的:探讨高分辨率CT(HRCT)诊断慢性中耳炎的的价值。方法:回顾分析56例(耳)慢性化脓性中耳炎,比较术前HRCT检查与手术所见。结果:胆脂瘤型中耳炎30例HRCT表现为鼓室或(及)鼓窦内团块软组织影和骨质改变,包括听骨移位、破坏,盾板破坏及中耳腔扩大,有的伴有乙状窦、天盖,水平半规管破坏;骨疡型中耳炎21例HRCT表现多呈斑片状、条索状或网状软组织影,部分可见液平面,听骨移位及破坏较轻;单纯型中耳炎HRCT表现大多无异常。HRCT所见与手术结果基本相符,符合率为96.4%。结论:HRCT有助于慢性化脓性中耳炎的诊断分型。  相似文献   
28.
MR成像是监测多发性硬化(MS)病情及其演变、评价疗效的重要手段,实验性自身免疫性脑脊髓炎(EAE)是公认的研究人类多发性硬化的动物模型。常规MR扫描仅能分析MS和EAE炎症反应的继发性改变。巨噬细胞是MS和EAE炎症反应中重要的效应细胞,超微超顺磁性氧化铁(USPIO)粒子能被巨噬细胞摄取,MR成像能显示MS和EAE病灶内吞噬了USPIO的巨噬细胞,分析其炎症反应自身的信息,是动态观察巨噬细胞浸润过程、进一步探索MS免疫病理机制的有效手段。本文综述超微超顺磁性对比剂的特性及其MR成像在EAE和MS病理机制方面的研究进展,评价其发展前景。  相似文献   
29.
Purpose. To estimate disease activity in patients with systemic sclerosis using contrast-enhanced MRI of the skin. Material and Methods. In a pre-study, sequences of a low-field (0.2 T) scanner (Artoscan, Esaote, Genova, Italy) were optimized for detection of intravenous contrast (0.1 mmol/l Gd-DTPA) in six patients with the autoimmune disease systemic scleroderma. Based on the results of the pre-study, 17 patients with scleroderma (7 sclerotic/10 active inflammatory disease) were scanned using gradient-spoiled 3D GRE sequences (FA 90 °, TR 100 ms, TE 18 ms), which had been established as most sensitive for intravenous contrast. Contrast enhancement of the skin was determined quantitatively by contrast-to-noise ratios (CNR), comparing post- to pre-contrast and dynamic scans (for 6 min, 1 acquisition/min). Patients in the chronic state with sclerodactylia and active inflammation of the hands were considered separately and compared to a control group (n = 10) matched according to age. Results. CNR increase after intravenous contrast was significantly higher in patients with active disease (86 ± 16 % increase) than sclerosing disease (29 ± 3 %, p < 0.05) and the control group (4 ± 2 %, p < 0.05). The dynamic examination showed a significantly slower decrease after the peak rise in the first minute in patients with active disease (CNR 15.4 ± 0.7 to 14.2 ± 1.4) than in those with chronic disease (14.1 ± 0.5 to 11.3 ± 0.9, p < 0.05). Discussion. Capillary leakage is the most likely explanation for the increased enhancement in patients with active scleroderma. Using sequences optimized for contrast detection, disease activity in the course of scleroderma and response to therapy can be determined by MRI in the future.   相似文献   
30.
Non-ionic contrast media (CM) are proven to be significantly safer than the high osmolar ionic contrast media (HOCM). Nevertheless deaths are reported after administration of non-ionic agents. The aim of the study was to investigate the rate of adverse reactions to non-ionic CM with special regard to high-risk patients and the effects of premedication with H1-and H2-receptor antagonists.In a prospective study conducted over about 2 years 12 995 examinations with intravenous or intra-arterial non-ionic CM were evaluated. Premedication with H1-and H2-antagonists was used in 1276 high-risk patients with known adverse reaction to CM, history of allergy or severe cardiac or pulmonary disease. 229 patients received no premedication inspite of known risk factors. In total, there were 143 (1.10%) adverse reactions (mild in 0.58%, moderate in 0.41% and severe in 0.05%). In high-risk patients there were adverse reactions in 4.37% without and in 1.57% with premedication. There were no severe adverse reactions in the high-risk patients after premedication. The age of the patient, CM dosage and CM concentration were not shown to be risk factors in the present study. In conclusion, the additional premedication with H1- and H2-antagonists could be an effective agent to reduce the risk of mild and moderate adverse reactions and to avoid severe adverse reactions in high-risk patients. Correspondence to: U. Fink  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