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   2506篇
  免费   165篇
  国内免费   13篇
耳鼻咽喉   27篇
儿科学   162篇
妇产科学   68篇
基础医学   383篇
口腔科学   40篇
临床医学   195篇
内科学   465篇
皮肤病学   96篇
神经病学   150篇
特种医学   42篇
外科学   232篇
综合类   24篇
预防医学   179篇
眼科学   76篇
药学   203篇
中国医学   21篇
肿瘤学   321篇
  2023年   17篇
  2022年   27篇
  2021年   74篇
  2020年   59篇
  2019年   81篇
  2018年   98篇
  2017年   67篇
  2016年   81篇
  2015年   95篇
  2014年   123篇
  2013年   150篇
  2012年   213篇
  2011年   218篇
  2010年   128篇
  2009年   104篇
  2008年   163篇
  2007年   116篇
  2006年   136篇
  2005年   134篇
  2004年   121篇
  2003年   105篇
  2002年   83篇
  2001年   45篇
  2000年   33篇
  1999年   30篇
  1998年   16篇
  1997年   12篇
  1996年   14篇
  1995年   9篇
  1994年   10篇
  1993年   8篇
  1992年   13篇
  1991年   13篇
  1990年   9篇
  1989年   10篇
  1988年   3篇
  1987年   4篇
  1986年   7篇
  1985年   4篇
  1984年   4篇
  1983年   5篇
  1982年   3篇
  1979年   3篇
  1976年   2篇
  1975年   3篇
  1974年   2篇
  1972年   5篇
  1970年   2篇
  1966年   2篇
  1954年   2篇
排序方式: 共有2684条查询结果,搜索用时 15 毫秒
61.
62.
Objective

To assess any potential association between Helicobacter pylori and oral squamous cell carcinoma/oral potentially malignant disorders.

Materials and methods

Data mining was done using PubMed, Cochrane Library, and SCOPUS databases. The search included articles published up to May 2019. Newcastle-Ottawa scale was used to score the quality of the included articles. Data including the type of study, the sample population, the type of oral lesion, and the resulting statistical data were extracted.

Results

Out of 131 screened articles, only 15 articles fulfilled the eligibility criteria. Among the 15 studies, 9 focused on oral squamous cell carcinoma and 6 focused on oral potentially malignant disorders. Eight out of the 9 oral squamous cell carcinoma studies were included in the meta-analysis. Forest plot was generated using the odds ratio and confidence intervals calculated for each of the included studies. Due to the lack of sufficient studies, the meta-analysis was not performed for oral potentially malignant disorders.

Conclusion

Due to the contradictory results of the included studies, it was not possible to make any conclusive statement on the potential association of H. pylori with oral squamous cell carcinoma. The variations in the methodology, especially the differences in the sensitivity/specificity of the diagnostic modalities could be the cause for differential results.

Clinical relevance

Although the association of H. pylori with oral squamous cell carcinoma could not be confirmed, it is vital to reduce the excess oral microbial load, especially in patients exhibiting oral mucosal changes with no history of associated risk factors.

  相似文献   
63.
64.
The way students are taught and evaluated is changing, with greater emphasis on flexible, individualized, learner‐centered education, including the use of technology. The goal of assessment is also shifting from what students know to how they perform in practice settings. Developing educational materials for teaching in these ways is time‐consuming and can be expensive. The Portal of Geriatrics Online Education (POGOe) was developed to aid educators in meeting these needs and become quicker, better‐prepared teachers of geriatrics. POGOe contains more than 950 geriatrics educational materials that faculty at 45% of allopathic and 7% of osteopathic U.S. medical schools and the Centers for Geriatric Nursing Excellence have created. These materials include various instructional and assessment methodologies, including virtual and standardized patients, games, tutorials, case‐based teaching, self‐directed learning, and traditional lectures. Materials with common goals and resource types are available as selected educational series. Learner assessments comprise approximately 10% of the educational materials. POGOe also includes libraries of videos, images, and questions extracted from its educational materials to encourage educators to repurpose content components to create new resources and to align their teaching better with their learners' needs. Web‐Geriatric Education Modules, a peer‐reviewed online modular curriculum for medical students, is a prime example of this repurposing. The existence of a robust compendium of instructional and assessment materials allows educators to concentrate more on improving learner performance in practice and not simply on knowledge acquisition. It also makes it easier for nongeriatricians to teach the care of older adults in their respective disciplines.  相似文献   
65.
Molecular mechanisms contributing to the tumorigenesis of pancreatic endocrine tumors (PETs) are still not well understood. Allelic deletions at chromosome 22q12.3 were detected in about 30-60% of PETs, suggesting that inactivation of one or more tumor suppressor genes on this chromosomal arm is important for their pathogenesis. Because the putative tumor suppressor gene tissue inhibitor of metalloproteinase-3 (TIMP-3) has been located at 22q12.3, we undertook a genetic analysis of TIMP-3 to determine its role in the tumorigenesis of PETs. Single-strand conformational polymorphism analysis, methylation-specific PCR, RNA expression analysis, and immunohistochemistry of TIMP-3 were performed in 21 sporadic PETs. Thirteen of 21 PETs (62%) revealed TIMP-3 alterations, including promoter hypermethylation and homozygous deletion. The predominant TIMP-3 alteration was promoter hypermethylation, identified in 8 of 18 (44%) PETs. It was tumor-specific and corresponded to loss or strong reduction of TIMP-3 protein expression. Notably, 11 of 14 (79%) PETs with metastases had TIMP-3 alterations, compared with only 1 of 7 (14%) PETs without metastases (P < 0.02). These data suggest a possibly important role of TIMP-3 in the tumorigenesis of human PETs, especially in the development of metastases, which has to be further evaluated in large-scale studies.  相似文献   
66.
Anemia is a major health burden worldwide and affects approximately one‐third of world's population. It is not a diagnosis; it is a manifestation of an underlying pathophysiology leading to either decreased hemoglobin (Hb), hematocrit (Hct), or red blood cells (RBCs). Iron deficiency anemia is still the most common cause of anemia worldwide. The symptoms are usually due to the underlying compensatory responses to decrease in oxygen delivery to the tissues. Laboratory investigation should start with complete blood count (CBC), reticulocyte count (RC), and peripheral smear evaluation. Further testing depends on these indices, that is, iron parameters and hemoglobinopathies/thalassemia evaluation in microcytic hypochromic anemia, vitamin B12, and folic acid level in macrocytic anemia. Increased RC denotes adequate bone marrow response and points toward hemolytic process and vice versa. Anemia diagnosis can be complex and confusing for the practicing physician. This review tries to give a practical simplistic approach to the diagnosis, focusing mainly on the basic parameters, that is, CBC, RC, and peripheral smear etc. Moreover, we have also tried to provide an update on the pyruvate kinase deficiency, as there has been recent exciting development in the management of these patients.  相似文献   
67.
Depressive symptoms are associated with an increased risk of death, but most of this association remains unexplained. Our aim was to explore the contribution of sleep duration and disturbances to the association between depressive symptoms, all‐cause and cardiovascular disease mortality. A total of 5813 (4220 men and 1593 women) aged 50–74 years at baseline, participants of the British Whitehall II prospective cohort study, were included. Depressive symptoms, sleep duration and disturbances were assessed in 2003–04. Mortality was ascertained through linkage to the national mortality register until August 2012, with a mean follow‐up of 8.8 years. Depressive symptoms were associated with an increased risk of mortality from all causes [hazard ratio (HR) = 1.51; 95% confidence interval (CI): 1.16–1.97)] and cardiovascular diseases (HR = 1.63; 95% CI: 1.01–2.64) after adjustment for sociodemographic characteristics. Further adjustment for sleep duration and disturbances reduced the association between depressive symptoms and cardiovascular mortality by 21% (HR = 1.53; 95% CI: 0.91–2.57). Sleep seems to have a role, as a mediator or confounder, in explaining the association between depressive symptoms and cardiovascular mortality. These findings need replication in larger studies with longer follow‐up.  相似文献   
68.
69.
Autosomal-dominant idiopathic infantile nystagmus has been linked to 6p12 (OMIM 164100), 7p11.2 (OMIM 608345) and 13q31-q33 (OMIM 193003). PAX6 (11p13, OMIM 607108) mutations can also cause autosomal-dominant nystagmus, typically in association with aniridia or iris hypoplasia. We studied a large multigenerational white British family with autosomal-dominant nystagmus, normal irides and presenile cataracts. An SNP-based genome-wide analysis revealed a linkage to a 13.4-MB region on chromosome 11p13 with a maximum lod score of 2.93. A mutation analysis of the entire coding region and splice junctions of the PAX6 gene revealed a novel heterozygous missense mutation (c.227C>G) that segregated with the phenotype and is predicted to result in the amino-acid substitution of proline by arginine at codon 76 p.(P76R). The amino-acid variation p.(P76R) within the paired box domain is likely to destabilise the protein due to steric hindrance as a result of the introduction of a polar and larger amino acid. Eye movement recordings showed a significant intrafamilial variability of horizontal, vertical and torsional nystagmus. High-resolution in vivo imaging of the retina using optical coherence tomography (OCT) revealed features of foveal hypoplasia, including rudimentary foveal pit, incursion of inner retinal layers, short photoreceptor outer segments and optic nerve hypoplasia. Thus, this study presents a family that segregates a PAX6 mutation with nystagmus and foveal hypoplasia in the absence of iris abnormalities. Moreover, it is the first study showing detailed characteristics using eye movement recordings of autosomal-dominant nystagmus in a multigenerational family with a novel PAX6 mutation.  相似文献   
70.
We report the design‐synthesis of several nitrothiophene containing molecules as antituberculosis agents. The molecules were designed on the basis of previously reported nitrofuran molecules in our laboratory, and the α,β‐unsaturated linker was modified to cyclized linker in order to overcome the challenge of low solubility and possible toxicity. The stereo‐electronic properties such as HOMO, LUMO, and HOMO‐LUMO gap along with other properties such as aqueous solvation energies and QPLogS values were studied. The designed molecules were synthesized and tested for in vitro antituberculosis activity, and some molecules were found to be highly active comparable to standard drugs. Further, the aqueous solubility was determined using visual inspection method and the designed molecules were found to be more soluble than their chalcone counterparts. Cytotoxicity studies were performed and the molecules were found to be non‐cytotoxic. Electroanalytical studies proved nitro reduction as the mechanism of action for these molecules. Thus, this study provides potential nitrothiophene containing hits with improved solubility and reduced chances of toxicity.  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