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   23213篇
  免费   1863篇
  国内免费   51篇
耳鼻咽喉   118篇
儿科学   869篇
妇产科学   726篇
基础医学   3176篇
口腔科学   352篇
临床医学   3187篇
内科学   4156篇
皮肤病学   316篇
神经病学   2757篇
特种医学   421篇
外国民族医学   1篇
外科学   2056篇
综合类   285篇
一般理论   48篇
预防医学   3083篇
眼科学   410篇
药学   1551篇
中国医学   30篇
肿瘤学   1585篇
  2023年   195篇
  2022年   214篇
  2021年   517篇
  2020年   369篇
  2019年   570篇
  2018年   629篇
  2017年   488篇
  2016年   492篇
  2015年   569篇
  2014年   830篇
  2013年   1201篇
  2012年   1675篇
  2011年   1745篇
  2010年   934篇
  2009年   891篇
  2008年   1425篇
  2007年   1577篇
  2006年   1586篇
  2005年   1463篇
  2004年   1442篇
  2003年   1331篇
  2002年   1228篇
  2001年   234篇
  2000年   192篇
  1999年   208篇
  1998年   250篇
  1997年   207篇
  1996年   160篇
  1995年   149篇
  1994年   118篇
  1993年   140篇
  1992年   110篇
  1991年   109篇
  1990年   89篇
  1989年   89篇
  1988年   68篇
  1987年   75篇
  1986年   54篇
  1985年   70篇
  1984年   66篇
  1983年   83篇
  1982年   85篇
  1981年   69篇
  1980年   78篇
  1979年   54篇
  1978年   46篇
  1977年   47篇
  1976年   52篇
  1974年   50篇
  1973年   63篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
The first case of AIDS patient in the northern part of Thailand was reported in 1987 (Vithayasai et al., 1996), marking the outbreak of an epidemic. In our experience, the neurological involvement in AIDS patients seems to have changed in pattern and incidence during the last 8 years. We have conducted a retrospective study to review the incidence of AIDS-defining diseases in the patients admitted to Chiang Mai University Hospital, Thailand during the period September 2001 to August 2002. There were 155 AIDS patients admitted during this specified period, 118 of which were male and 37 female, aged between 16 and 60. The incidence of neurological complications was 50.3 per 100 person-years, in which central nervous system involvement account for 46.5 per 100 person-years and peripheral nervous system involvement account for 3.8 per 100 person-years. The incidence of cryptococcal meningitis appeared to be decreasing since 1994 whereas the incidence of cerebral toxoplasmosis appeared to be increasing. The incidence of cryptococcal meningitis, cerebral toxoplasmosis and cytomegalovirus (CMV) infection was 18.0, 14.8 and 7.0 per 100 person-years, respectively. Other common non-neurological AIDS-defining illnesses in northern Thailand include pulmonary tuberculosis (15.4 per 100 person-years), extra-pulmonary tuberculosis (9.6 per 100 person-years), and disseminated penicilliosis (12.2 per 100 person-years). In this way and summarizing, in northern Thailand, the three most common neurological involvements before the era of highly active anti-retroviral therapy are cryptococcal meningitis, cerebral toxoplasmosis and CMV infection. The incidence of cryptococcal meningitis appeared to be decreasing whereas the incidence of cerebral toxoplasmosis seemed to be increasing.  相似文献   
82.
BACKGROUND CONTEXT: Although crystal deposition in cartilage and synovial fluid has received much attention, crystal formation and the role that crystal deposits play are virtually unexplored in the intervertebral disc. In articular cartilage matrix, crystal deposits are associated with altered extracellular matrix (ECM) and cell phenotypic features, but crystal deposition in the human intervertebral disc has received much less attention. PURPOSE: To determine the incidence of crystal deposits in the annulus and to evaluate associated disc cell and ECM features. STUDY DESIGN/SETTING: Human intervertebral disc annulus tissue was obtained in a prospective study of the presence of crystals in the disc ECM. Human Subjects Institutional Review Board approved experimental studies. PATIENT SAMPLE: Two hundred eight sequential disc specimens were submitted from surgical disc procedures performed on individuals with herniated discs, degenerative disc disease, or recurrent disc herniation. During this same time period, three disc specimens were received from nonsurgical donors and added to the study population. OUTCOME MEASURES: Histologic features with special attention to crystal deposition. METHODS: Specimens were processed undecalcified and examined for the histologic presence of crystal deposits and ECM features around the crystals. RESULTS: The proportion of specimens containing crystals was determined to be 14.7%; crystals displayed varying sizes, morphology, and polarized light birefringence features. Pyrophosphate crystals were most common, but oxalate-like crystals were also present. ECM in crystal regions showed previously recognized alterations. CONCLUSIONS: This study shows that the incidence of crystal deposits in discs is approximately 15% and is thus a relatively common occurrence. These data are important because masses of crystals not only disrupt disc ECM but may also accelerate preexisting degenerative changes via an elevation in matrix metalloproteinases (as previously recognized in cartilage). Because failure of the structural integrity of the disc can result in annular tears and subsequent disc herniation, the mechanisms of crystal formation and the relationship between crystals and disc degeneration merit further investigations.  相似文献   
83.
Parkin mutations account for the majority of familial and sporadic early onset Parkinson's disease (EOPD) cases with a known genetic association. More than 100 mutations have been described in the Parkin gene that includes homozygous, compound heterozygous, and single heterozygous mutations. We have designed a Parkin mutation genotyping array (gene chip) that includes published Parkin sequence variants and allows their simultaneous detection. The chip was validated by screening 85 PD cases and 47 controls previously tested for Parkin mutations. Similar genotyping microarrays have been developed for other genetically heterogeneous diseases including age-related macular degeneration. Here, we show the utility of a genotyping array for Parkinson's disease by analysis of 60 subjects from the Genetic Epidemiology of Parkinson Disease (GEPD) study that includes 15 early-onset PD case probands and 45 relatives.  相似文献   
84.
PURPOSE: Elective cosmetic surgery is expanding in the UK in both the public and private sectors. Because resources are constrained, many cosmetic procedures are being excluded within the National Health Service. If guidelines on who can receive such surgery are to be evidence-based, information is needed about the level of dysfunction in patients referred for elective surgery and whether this is related to their degree of physical abnormality. METHOD: Consecutive patients referred to a regional plastic surgery and burns unit for assessment for elective cosmetic surgery completed standardised measures of physical and psychosocial dysfunction, and indicated their perception of the degree of their abnormality and their preoccupation with it. We distinguished between patients referred for physical reasons or appearance reasons only, and compared levels of physical and psychosocial dysfunction in each with published values for community and clinical samples. Surgeons indicated patients' degree of objective abnormality, and we identified the relationship of dysfunction with perceived and objective abnormality and preoccupation. RESULTS: Whether patients sought surgery for physical or appearance reasons, physical function was normal. Those seeking surgery for appearance reasons only had moderate psychosocial dysfunction, but were not as impaired as clinical groups with psychological problems. Patients seeking the correction of minor skin lesions for purely appearance reasons reported excellent physical and psychosocial function. Level of function was related (negatively) to patients' preoccupation with abnormality rather than to their perceived or objective abnormality. CONCLUSIONS: In general, patients referred for elective cosmetic surgery did not present with significant levels of dysfunction. Moreover, levels of functioning were related to preoccupation rather than to objective abnormality. Therefore, for most patients, whether surgical treatment is generally appropriate is questionable. Future guidelines must seek to identify the small minority who do have a clinical need for surgery.  相似文献   
85.
BACKGROUND: Linkage studies by us and others have confirmed that chromosome 1q23.3 is a susceptibility locus for schizophrenia. Based on this information, several research groups have published evidence that markers within both the RGS4 and CAPON genes, which are 700 kb apart, independently showed allelic association with schizophrenia. Tests of allelic association with both of these genes in our case control sample were negative. Therefore, we carried out further fine mapping between the RGS4 and CAPON genes. METHODS: Twenty-nine SNP and microsatellite markers in the 1q23.3 region were genotyped in the United Kingdom based sample of 450 cases and 450 supernormal control subjects. RESULTS: We detected positive allelic association after the eighth marker was genotyped and found that three microsatellite markers (p = .011, p = .014, p = .049) and two SNPs (p = .004, p = .043) localized in the 700 kb region between the RGS4 and CAPON genes, within the UHMK1 gene, were associated with schizophrenia. Tests of significance for marker rs10494370 remained significant following Bonferroni correction (alpha = .006) for multiple tests. Tests of haplotypic association were also significant for UHMK1 (p = .009) using empirical permutation tests, which make it unnecessary to further correct for both multiple alleles and multiple markers. CONCLUSIONS: These results provide preliminary evidence that the UHMK1 gene increases susceptibility to schizophrenia. Further confirmation in adequately powered samples is needed. UHMK1 is a serine threonine kinase nuclear protein and is highly expressed in regions of the brain implicated in schizophrenia.  相似文献   
86.
87.
Changes in the design of hospital wards have usually been determined by architects and members of the nursing and medical professions, the views and preferences of patients have seldom been sought directly The Hospital Anxiety and Depression scale and the Disturbance Due to Hospital Noise questionnaire were administered to 64 female patients on bay and Nightingale wards together with a questionnaire designed for this study Perceptions of social and physical factors of ward design were examined, and their relationship to psychological well-being and sleep patterns The results show that the bay ward seemed to offer a more favourable environment for patients but some of the disadvantages of bay wards are balanced by better staffing levels and better and more modern facilities Visibility to nurses was lower on the bay ward The Nightingale ward was perceived as significantly noisier than the bay ward and noise levels were significantly correlated to anxiety scores Paradoxically the increase in noise levels appeared to improve the perceived level of privacy on the Nightingale ward Seventy-five per cent of patients were found to prefer the bay ward design, and since neither design appears to have major disadvantages their continued introduction should be encouraged However, recommendations are made concerning the optimizing of patients' well-being within the bay ward setting  相似文献   
88.
89.
EMG responses in the external anal sphincter (EAS), the rectus abdominis muscle (RA), and the anterior tibial muscle (TA) were recorded following single magnetic transcranial cortical stimulations (TCCS) in seven healthy volunteers. The responses in the EAS differed from the responses in the other muscles. They had comparatively long durations ranging from 1 to 2 seconds, no inhibitory periods were observed, and there was no tendency for habituation to occur following a limited number of stimuli. The responses recorded in the EAS were used as test responses in order to evaluate the excitability changes in the EAS motoneurons occurring during bladder filling. Cystometries with filling rates of 15, 50 and 200 ml/min were done. During these cystometries TCCS were applied repeatedly, with constant strength, after each 50 ml of filling up to bladder capacity. The responses following TCCS changed in a highly reproducible way during bladder filling. After 100–200 ml of filling, the responses had longer latencies, diminished sizes, and shorter durations. When the filling reached a level 50–150 ml below capacity, the responses in most subjects again became greater and the latencies shorter. The changes were believed to be physiological. It was concluded that the EAS motoneurons are under both inhibitory and facilitatory influence during bladder filling in intact healthy humans. Facilitatory influences are often observed when the bladder is filled close to capacity. At lower bladder volumes the observed influence is always inhibitory. A decrease in the EMG activity of the EAS during filling cystometry should consequently not be regarded as a pathological response.  相似文献   
90.
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