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   13950篇
  免费   655篇
  国内免费   119篇
耳鼻咽喉   95篇
儿科学   276篇
妇产科学   408篇
基础医学   1720篇
口腔科学   354篇
临床医学   958篇
内科学   3959篇
皮肤病学   217篇
神经病学   1312篇
特种医学   583篇
外科学   2095篇
综合类   34篇
一般理论   1篇
预防医学   500篇
眼科学   155篇
药学   694篇
中国医学   23篇
肿瘤学   1340篇
  2024年   12篇
  2023年   89篇
  2022年   201篇
  2021年   410篇
  2020年   207篇
  2019年   298篇
  2018年   390篇
  2017年   289篇
  2016年   323篇
  2015年   361篇
  2014年   551篇
  2013年   701篇
  2012年   971篇
  2011年   990篇
  2010年   642篇
  2009年   582篇
  2008年   1000篇
  2007年   998篇
  2006年   906篇
  2005年   951篇
  2004年   848篇
  2003年   780篇
  2002年   695篇
  2001年   79篇
  2000年   69篇
  1999年   99篇
  1998年   147篇
  1997年   108篇
  1996年   128篇
  1995年   85篇
  1994年   98篇
  1993年   79篇
  1992年   65篇
  1991年   54篇
  1990年   51篇
  1989年   43篇
  1988年   31篇
  1987年   20篇
  1986年   34篇
  1985年   31篇
  1984年   30篇
  1983年   23篇
  1982年   32篇
  1981年   33篇
  1980年   31篇
  1979年   20篇
  1976年   10篇
  1975年   8篇
  1974年   8篇
  1964年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Helicobacter pylori (HP) infection is a common and persistent disorder acting as a major cofactor for the development of upper gastrointestinal diseases and several extraintestinal disorders including osteoporosis. However, no prospective study assessed the effects of HP on bone health and fracture risk. We performed a HP screening in a population-based cohort of 1149 adults followed prospectively for up to 11 years. The presence of HP infection was assessed by serologic testing for serum antibodies to HP and the cytotoxin associated gene-A (CagA). The prevalence of HP infection did not differ among individuals with normal bone mineral density (BMD), osteoporosis, and osteopenia. However, HP infection by CagA-positive strains was significantly increased in osteoporotic (30%) and osteopenic (26%) patients respect to subjects with normal BMD (21%). Moreover, anti-CagA antibody levels were significantly and negatively associated with lumbar and femoral BMD. Consistent with these associations, patients affected by CagA-positive strains had a more than fivefold increased risk to sustain a clinical vertebral fracture (HR 5.27; 95% CI, 2.23–12.63; p < .0001) and a double risk to sustain a nonvertebral incident fracture (HR 2.09; 95% CI, 1.27–2.46; p < .005). Reduced estrogen and ghrelin levels, together with an impaired bone turnover balance after the meal were also observed in carriers of CagA-positive HP infection. HP infection by strains expressing CagA may be considered a risk factor for osteoporosis and fractures. Further studies are required to clarify in more detail the underlying pathogenetic mechanisms of this association. © 2020 American Society for Bone and Mineral Research (ASBMR).  相似文献   
82.
83.
84.
BackgroundIn severe cases of ankle and subtalar arthritis, arthrodesis of the subtalar joint is performed in combination with ankle arthroplasty. In these special cases gait analysis reveals real motion at the replaced tibiotalar joint.MethodsTwenty-three patients affected by ankle and subtalar arthritis, treated either with a 3-component or a 2-component prosthesis in combination with subtalar arthrodesis, were clinically evaluated preoperatively and at a minimum of 1-year follow-up. Gait analysis was performed postoperatively using a multi-segment foot protocol. Foot kinematics were compared to corresponding data from a healthy control group.ResultsClinical scores significantly improved from preoperative to follow-up. The clinically measured passive ankle dorsiflexion/plantarflexion significantly improved at the follow-up. Patients’ normalized walking speed and stride length were significantly lower than those in control. With exception of the ankle frontal-plane motion, sagittal-plane mobility of foot joints was about 50% than that in healthy joints.ConclusionsImprovement in clinical scores was found for both prostheses. Normal spatio-temporal parameters were not restored. In these patients, fusion of the subtalar joint appeared to be compensated by larger frontal-plane motion at the tibiotalar joint.Level of evidenceLevel III- retrospective comparative study.The study was approved by the local Ethics Committee as protocol MAT (protocol registration at clinicaltrials.gov NCT03356951).  相似文献   
85.
With hindsight, the main weakness behind the ineffective response to the coronavirus disease 2019 (COVID-19) pandemic in some countries has been the failure to understand, and take account of, the multilayered systemic interdependencies that spread the effects of the pandemic across social, technological, economic and health-care dimensions. For example, to respond to the COVID-19 pandemic, all people were required to rapidly adjust to social distancing and travel restrictions. Such a complex behavioural response entails adaptation to achieve a full recovery from the systemic shock. To capitalize on the positive effects of disruption to the status quo, much more complex socioeconomic modelling needs to be considered when designing and evaluating possible public health interventions that have major behavioural implications. We provide a simple example of how this reasoning may highlight generally unacknowledged connections and interdependencies and guide the construction of scenarios that can inform policy decisions to enhance the resilience of society and tackle existing societal challenges.  相似文献   
86.
This study identifies gaps in universal health coverage in the European Union, using a questionnaire sent to the Health Systems and Policy Monitor network of the European Observatory on Health Systems and Policies. The questionnaire was based on a conceptual framework with four access dimensions: population coverage, service coverage, cost coverage, and service access. With respect to population coverage, groups often excluded from statutory coverage include asylum seekers and irregular residents. Some countries exclude certain social-professional groups (e.g. civil servants) from statutory coverage but cover these groups under alternative schemes. In terms of service coverage, excluded or restricted services include optical treatments, dental care, physiotherapy, reproductive health services, and psychotherapy. Early access to new and expensive pharmaceuticals is a concern, especially for rare diseases and cancers. As to cost coverage, some countries introduced protective measures for vulnerable patients in the form of exemptions or ceilings from user chargers, especially for deprived groups or patients with accumulation of out-of-pocket spending. For service access, common issues are low perceived quality and long waiting times, which are exacerbated for rural residents who also face barriers from physical distance. Some groups may lack physical or mental ability to properly formulate their request for care. Currently, available indicators fail to capture the underlying causes of gaps in coverage and access.  相似文献   
87.
Nine patients undergoing regular dialytic treatment for more than 60 months showed clinical and radiologic features of a noninfective and destructive spondyloarthropathy. The cervical spine was most affected (100%), followed by the dorsal (three patients, 33.3%) and the lumbar spine (two patients, 22.2%). Typically, radiographs and CT scans revealed narrowing of intervertebral spaces, with destruction or sclerosis of the subchondral bone of the vertebral plate.Autopsy was performed on three patients; histologic study demonstrated the presence of large amyloid deposits containing 2-microglobulin ( 2-m) in the discs and peridiscal ligaments.A radiographic follow-up of the cervical spine was performed in seven patients after a period of 12 months and showed that the bone destruction in DSA is very rapid and progressive. The lower biocompatibility of the cuprophan membranes of dialyzers is probably the factor most responsible for hyperproduction of 2-m and subsequently osteoarticular deposition of a new type of amyloidosis.  相似文献   
88.
A young woman with a thyroid papillary carcinoma behaving as an autonomously hyperfunctioning nodule is described. Only 17 similar patients have been seen in the past 25 years. It is emphasized that hyperthyroidism does not exclude malignant disease in hot nodules. This possibility suggests that all thyroid nodules, either cold or hot, require careful management. Therefore, in at risk cases, surgery could be the most useful treatment.  相似文献   
89.
Between 1953 and 1989 eighty cases of non-traumatic brain abscess were treated in our department. We have re-examined the clinical and neuroradiological features of this pathological process and present our therapeutic approach and results. We believe that the optimal treatment for brain abscess consists of surgical removal.The prognosis for these lesions has undergone a marked improvement over the last two decades in response to neuroradiological, microbiological and surgical advances. The most influential prognostic factor seems to be preoperative clinical status.  相似文献   
90.
Summary The interaction of locally perfused cholecystokinin-8 (sulphated) with systemically administered apomorphine was studied on the release of dopamine and its metabolites using microdialysis in the neostriatum of the halothane-anaesthetized male rat. Dialysate levels of dopamine, 3,4-dihydroxyphenylacetic acid and homovanillic acid were assayed by high performance liquid chromatography in combination with electrochemical detection. Perfusion with cholecystokinin-8 (100 M but not 1 M or 10 nM) increased the dialysate levels of dopamine without affecting those of DOPAC or HVA. At low concentrations (1 M and 10 nM but not 1 nM), cholecystokinin-8 counteracted the inhibitory effect of apomorphine (0.05 mg/kg, s. c.) on dopamine release. This counteraction was antagonized by perfusion with the cholecystokinin-8 antagonist proglumide (3 M). At this concentration, proglumide perfused alone was without effect on basal or apomorphine-reduced levels of dopamine. The results indicate a facilitatory effect of cholecystokinin-8 on dopamine release in rat neostriatum only at high concentrations. At lower concentrations, cholecystokinin-8 appears to modulate dopamine release by an inhibitory effect on dopamine autoreceptors possibly involving an intramembrane interaction between presynaptic cholecystokinin-8 receptors and dopamine autoreceptors. Send offprint requests to K. Fuxe at the above address  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