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   10718篇
  免费   576篇
  国内免费   56篇
耳鼻咽喉   137篇
儿科学   272篇
妇产科学   217篇
基础医学   1603篇
口腔科学   347篇
临床医学   1059篇
内科学   2164篇
皮肤病学   176篇
神经病学   1204篇
特种医学   178篇
外科学   939篇
综合类   38篇
一般理论   5篇
预防医学   1151篇
眼科学   105篇
药学   919篇
中国医学   57篇
肿瘤学   779篇
  2024年   9篇
  2023年   85篇
  2022年   202篇
  2021年   421篇
  2020年   260篇
  2019年   357篇
  2018年   382篇
  2017年   274篇
  2016年   271篇
  2015年   328篇
  2014年   494篇
  2013年   598篇
  2012年   925篇
  2011年   974篇
  2010年   485篇
  2009年   441篇
  2008年   695篇
  2007年   744篇
  2006年   617篇
  2005年   608篇
  2004年   562篇
  2003年   480篇
  2002年   443篇
  2001年   49篇
  2000年   32篇
  1999年   54篇
  1998年   87篇
  1997年   73篇
  1996年   48篇
  1995年   47篇
  1994年   47篇
  1993年   38篇
  1992年   25篇
  1991年   21篇
  1990年   19篇
  1989年   12篇
  1988年   13篇
  1987年   9篇
  1986年   7篇
  1985年   12篇
  1984年   13篇
  1983年   10篇
  1982年   19篇
  1981年   11篇
  1980年   10篇
  1979年   8篇
  1978年   6篇
  1977年   3篇
  1976年   6篇
  1974年   3篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Lasers in Medical Science - Acne vulgaris is the most recurring skin condition in the world, causing great harm to the physical and psychological well-being of many patients. Antimicrobial...  相似文献   
82.
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   
83.
84.
Highly effective CFTR modulator drug therapy is increasingly available to those with cystic fibrosis. Multiple observational research studies are now being conducted to better understand the impacts of this important therapeutic milestone on long-term outcomes, patient care needs, and future research priorities. PROMISE is a large, multi-disciplinary academic study focused on the broad impacts of starting elexacaftor/tezacaftor/ivacaftor in the US population age 6 years and older. The many areas of investigation and rationale for each are discussed by organ systems, along with recognition of remaining important questions that will not be addressed by this study alone. Knowledge gained through this and multiple complementary studies around the world will help to understand important health outcomes, clinical care priorities, and research needs for a large majority of people treated with these or similarly effective medications targeting the primary cellular impairment in cystic fibrosis.  相似文献   
85.

Syphilis among men who have sex with men (MSM) has increased greatly in the past twenty years in the U.S. Geographically explicit ecological momentary assessment (GEMA), in which behaviors are geotagged and contextualized in time and space, may contribute to a greater understanding of transmission risk. The objective was to determine the acceptability and feasibility of GEMA for assessing HIV and syphilis transmission risk behaviors among a sample of MSM. Participants responded to a brief survey five times a day for two weeks. Feasibility was measured by participant recruitment, enrollment, prompts received and answered, geotagged prompts, and technical interference with data collection. Acceptability was measured by ratings of enjoyment and willingness for future participation. Summaries of five behavioral measures from the brief survey were calculated. Among the 83 participants contacted, 67.5% (56) expressed interest, 98% (55) were scheduled, and 81.8% (45) were enrolled. Participants answered 78.3% (2,277) of prompts received and 87.7% (1,998) of answered prompts were geotagged. Overall, 70.5% (31) enjoyed participating and 91.1% (41) were willing to participate in the future. Among prompts answered, missingness was low for five behavioral measures (range 0.2% (4) to 0.7% (16)). Feasibility and acceptability were high and missingness was low on behavioral measures in this MSM study population. Most participants reported that they would participate again. Future work should focus on whether GEMA improves our understanding of syphilis and HIV transmission risk.

  相似文献   
86.
Myofibroma (MF) is a benign mesenchymal myofibroblast-derived tumor, which occurs most frequently in children, and rarely affects the maxilla. We reported a case of an aggressive intraosseous lesion found in the maxilla of a 9-year-old female child. Intraorally, the swelling extended from tooth 12 to 16, causing displacement of teeth 13, 14, and 15. Computed tomography revealed a large osteolytic lesion causing thinning and cortical erosion. Microscopically, the lesion showed a proliferation of spindle-shaped cells, with elongated nuclei and eosinophilic cytoplasm, arranged in interlaced fascicles. The immunohistochemical analysis revealed cytoplasmic positivity for α-SMA and HHF-35, and negativity for desmin, laminin, S-100, β-catenin, and CD34. Ki-67 was positive in 8% of tumor cells. The diagnosis was MF. Herein, we describe an additional case of central MF arising in the maxilla, including clinical, imaging, microscopical, and immunohistochemical features, as well as a review of the literature.  相似文献   
87.
Zika virus, influenza, and Ebola have called attention to the ways in which infectious disease outbreaks can severely – and at times uniquely – affect the health interests of pregnant women and their offspring. These examples also highlight the critical need to proactively consider pregnant women and their offspring in vaccine research and response efforts to combat emerging and re-emerging infectious diseases. Historically, pregnant women and their offspring have been largely excluded from research agendas and investment strategies for vaccines against epidemic threats, which in turn can lead to exclusion from future vaccine campaigns amidst outbreaks. This state of affairs is profoundly unjust to pregnant women and their offspring, and deeply problematic from the standpoint of public health. To ensure that the needs of pregnant women and their offspring are fairly addressed, new approaches to public health preparedness, vaccine research and development, and vaccine delivery are required. This Guidance offers 22 concrete recommendations that provide a roadmap for the ethically responsible, socially just, and respectful inclusion of the interests of pregnant women in the development and deployment of vaccines against emerging pathogens. The Guidance was developed by the Pregnancy Research Ethics for Vaccines, Epidemics, and New Technologies (PREVENT) Working Group – a multidisciplinary, international team of 17 experts specializing in bioethics, maternal immunization, maternal-fetal medicine, obstetrics, pediatrics, philosophy, public health, and vaccine research and policy – in consultation with a variety of external experts and stakeholders.  相似文献   
88.
89.
90.
Based on the hypothesis that free radicals play a general role in the neurodegenerative process in motor neuron disease, we tested selegiline in a group of patients affected by amyotrophic lateral sclerosis (ALS) to examine whether it might modify the progression of the disease. Patients were admitted if they were 25–80 years old and had a confirmed diagnosis of ALS with symptoms lasting no longer than 24 months. Patients with familial ALS, pure progressive bulbar palsy, primary lateral sclerosis or progressive muscle atrophy were excluded; a total of 111 patients were recruited. Fifty-three patients were randomly assigned to receive the drug (selegiline 10 mg/day orally for 6 months) and the remaining 58 were considered ALS controls. Mortality was similar in the two groups (4 and 5 patients respectively), though the difference was not statistically significant. Among the survivors, mean MRC and Norris disability scores and forced vital capacity were fairly similar in the two groups at all times and no statistically significant difference between treated and untreated patients was found. The results did not change when the data were related to age, duration and characteristics of onset of the disease. The rate of progression was significantly more rapid in patients with bulbar symptoms in both groups. Our data do not show any significant effect of selegiline in modifying the progression of ALS.  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