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   48371篇
  免费   3922篇
  国内免费   116篇
耳鼻咽喉   378篇
儿科学   1926篇
妇产科学   1304篇
基础医学   6879篇
口腔科学   986篇
临床医学   6616篇
内科学   9452篇
皮肤病学   905篇
神经病学   4897篇
特种医学   1164篇
外科学   4297篇
综合类   453篇
一般理论   62篇
预防医学   5869篇
眼科学   705篇
药学   2710篇
  2篇
中国医学   55篇
肿瘤学   3749篇
  2024年   138篇
  2023年   469篇
  2022年   614篇
  2021年   1326篇
  2020年   1005篇
  2019年   1428篇
  2018年   1562篇
  2017年   1222篇
  2016年   1348篇
  2015年   1421篇
  2014年   1808篇
  2013年   2668篇
  2012年   3702篇
  2011年   3833篇
  2010年   2105篇
  2009年   1864篇
  2008年   3090篇
  2007年   3187篇
  2006年   3129篇
  2005年   2956篇
  2004年   2858篇
  2003年   2634篇
  2002年   2358篇
  2001年   412篇
  2000年   293篇
  1999年   345篇
  1998年   529篇
  1997年   404篇
  1996年   362篇
  1995年   350篇
  1994年   278篇
  1993年   278篇
  1992年   213篇
  1991年   183篇
  1990年   169篇
  1989年   118篇
  1988年   145篇
  1987年   104篇
  1986年   113篇
  1985年   114篇
  1984年   111篇
  1983年   113篇
  1982年   137篇
  1981年   125篇
  1980年   108篇
  1979年   64篇
  1978年   68篇
  1977年   49篇
  1976年   47篇
  1972年   36篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
OBJECTIVE: We sought to investigate the prevalence of Candida carriage and the relationships between salivary flow rates and oral Candida load in patients with Sj?gren's syndrome (SS). METHODS: The oral Candida load of patients with SS was evaluated by culturing oral rinse (swish and spit) samples. Culture, Gram stain, and wet-mount test results were reported. RESULTS: One hundred three patients (96 women) met European criteria for SS (91 with primary SS and 12 with secondary SS). The mean age (95% confidence interval) was 55 years (range, 51-57 years). Oral rinse cultures were positive in 77% of subjects. The total stimulated salivary flow rate was inversely correlated with oral Candida load (r = -0.47; P 相似文献   
42.
The 22q11.2 deletion syndrome is characterized by wide phenotypic variability, frequently involving characteristic craniofacial features, cardiac malformations, and learning difficulties. Skeletal anomalies are also common and include an obtuse angle of the cranial base, retrognathia, and cervical spine abnormalities. Despite these anomalies, sleep-disturbed breathing is not reported frequently in patients with 22q11.2 deletion syndrome. We describe a patient with an obstructive sleep disturbance that was successfully treated with a tonsillectomy followed by mandibular distraction osteogenesis. She also had central sleep apnea, initially attributed to spinal cord impingement from cervical instability. Posterior cervical fusion was associated with a decrease in the number of central apneic events.  相似文献   
43.
OBJECTIVE: To describe a novel set of scaphocephaly severity indices (SSIs) for predicting and quantifying head- and skull-shape deformity in children diagnosed with isolated sagittal synostosis (ISS) and compare their sensitivity and specificity with those of the traditional cranial index (CI). METHODS: Computed tomography head scans were obtained from 60 patients diagnosed with ISS and 41 age-matched control patients. Volumetric reformations of the skull and overlying skin were used to trace two-dimensional planes defined in terms of skull-base plane and internal or surface landmarks. For each patient, novel SSIs were computed as the ratio of head width and length as measured on each of these planes. A traditional CI was also calculated and a receiver operating characteristic curve analysis was applied to compare the sensitivity and specificity of the proposed indices with those of CI. RESULTS: Although the CI is a sensitive measure of scaphocephaly, it is not specific and therefore not a suitable predictor of ISS in many practical applications. The SSI-A provides a specificity of 95% at a sensitivity level of 98%, in contrast with the 68% of CI. On average, the sensitivity and specificity of all proposed indices are superior to those of CI. CONCLUSIONS: Measurements of cranial width and length derived from planes that are defined in terms of internal or surface landmarks and skull-base plane produce SSIs that outperform traditional CI measurements.  相似文献   
44.
Primary care providers' involvement with and perceptions of the epidemic of early childhood caries could be related to attitudes and knowledge of the disease as well as to differences in discipline-based recommendations. A cross-sectional survey of demographics, opinions on infant oral health care visits and importance of infant oral health care, knowledge of tooth eruption, and knowledge of health care guidelines of the American Academy of Pediatrics (AAP) and American Academy of Pediatric Dentistry (AAPD) was administered by several methods to first- and fourth-year dental and medical students at two University of Illinois campuses. Some expected variations were found among dental and medical students pertaining to perceptions and knowledge of infant oral health. Higher proportions of dental students responded correctly or considered the issues very important. However, Rockford medicine students were more likely to know when children should be weaned, yet less likely to agree with recommendations for time of first dental visit. Furthermore, fourth-year dental students were less likely than first-year dental students to give the recommended answer for age of first dental visit. Variances of opinions and basic knowledge of infant oral health of dental and medical students showed inconsistencies with desired outcomes of educational and clinical experiences. Further research is needed to understand the role of experience and other factors to effectively educate primary care providers in this area.  相似文献   
45.

Background

Although basement membrane was traditionally considered an inert barrier that tumour cells had to cross before invasion into the surrounding stroma, recent studies suggest that basement membrane components are not only degraded during tumour progression, but also newly synthesised at the invasive front.

Objective

This study aimed at evaluating (1) the expression of basement membrane proteins in human oral carcinogenesis and (2) the role that epithelial-mesenchymal interactions play on it, by using an in vitro oral cancer progression model.

Material and methods

In vitro three-dimensional (3D) organotypic cultures of normal, early neoplastic and neoplastic human oral mucosa were developed by growing primary normal human oral keratinocytes, dysplastic human oral keratinocytes (DOK cell line), and neoplastic human oral keratinocytes (PE/CA-PJ15 cell line) on type I collagen biomatrices, with or without primary fibroblasts isolated from normal human oral mucosa. The cultured tissues were immunohistochemically assessed for the expression of the major basement membrane proteins laminin-332, type IV collagen, and fibronectin.

Results

Expression of laminin-332, type IV collagen, and fibronectin was gradually more pronounced in neoplastic models when compared to normal mucosa models, and, with the exception of laminin-332, it was further enhanced by presence of fibroblasts. Deposition of type IV collagen at the epithelium-biomatrix interface occurred only in presence of fibroblasts, as well as the extracellular matrix deposition of fibronectin.

Conclusions

These findings, obtained in a 3D in vitro model that closely mirrors the in vivo human oral cancer progression, show an enhanced basement membrane protein expression during human oral cancer progression that is dependent on the epithelial-mesenchymal environment, respectively the existence of fibroblasts.  相似文献   
46.
T-lymphocyte subsets in recurrent aphthous ulceration   总被引:10,自引:0,他引:10  
Peripheral T-lymphocyte subsets: T-helper (OKT4) and T-suppressor (OKT8) cells were studied quantitatively in 20 patients with recurrent aphthous ulceration (RAU) in ulcerative, as well as inactive, stages of the disease. The figures were compared with T-lymphocyte subsets from matched control donors with no history of RAU. The ratio of T-helper: T-suppressor cells was significantly lower in both stages in the patients compared with controls due to a significantly increased number of T-suppressor cells in RAU patients. The number of T-helper cells in the patients did not differ significantly in either stage compared with controls. The study support the hypothesis of recurrent aphthous ulceration being a disorder of immunodeficiency.  相似文献   
47.
The aim of the investigation was to collect information from specialized hospitals regarding dental care before and after organ transplantation or replacement of prosthetic joints. 50 transplantation centres and 100 orthopaedic hospitals in Germany were chosen. A questionnaire was used to elucidate the following aspects: Is a dental examination carried out preoperatively? When the patient is discharged, is he or she recommended to have antibiotic prophylaxis before dental treatment? If so, which antibiotic is recommended? The response rate was 56% (n = 28) for transplantation centres. 89% arranged a dental examination before the transplantation. 83% of those questioned recommend antibiotic prophylaxis before dental treatment: Amoxicillin was mentioned most frequently (36%). The response rate of the orthopaedic hospitals was 31% (n = 31). 3% of those questioned arranged a dental examination before insertion of an endoprothesis. 55% recommend antibiotic prophylaxis when dental treatment is to be carried out following the insertion of the endoprosthesis. Cephalosporine was most frequently mentioned (33%). It was not possible to identify a uniform recommendation regarding dental care before and after organ transplantation or replacement of prosthetic joints either for patients with an organ transplant or those having a prosthetic joint.  相似文献   
48.
BACKGROUND: The aim of this study was to evaluate the gingival blood flow of smokers and non-smokers with periodontal disease before and after surgical periodontal treatment. METHODS: Nine smokers and six non-smokers with at least two periodontal lesions were included in the study. Laser Doppler flowmetry was used to measure blood flow in two gingival sites and two skin sites. Two intrabony defects were treated surgically at the same time; enamel matrix derivative was applied at random to one of the sites, whereas the other site received a placebo gel. We measured resting gingival blood flow (GBF) and responses to cold pressor test (CPT) and to smoking and made continuous measurements of blood pressure (BP). Resting GBF levels of 26 young healthy subjects were used as a reference value. RESULTS: Resting GBF was significantly lower for the periodontitis patients compared to the reference subjects, regardless of smoking habits. GBF and gingival vascular conductance (VC) decreased significantly pre- and postoperatively in response to smoking. CPT evoked significant decreases in VC in smokers and non-smokers. Skin blood flow decreased significantly in response to CPT, more so in the non-smokers. BP was significantly higher in the non-smokers. CONCLUSIONS: Resting GBF of periodontitis patients was not lower in smokers than in non-smokers, but it was significantly lower than in the younger reference subjects. In contrast to our earlier findings in healthy subjects, smoking one cigarette may cause a decrease in GBF and VC in periodontitis patients. These observations suggested the existence of a dysfunction in the gingival vasculature in smokers and non-smokers with periodontitis.  相似文献   
49.
International Journal of Paediatric Dentistry 2011; 21: 289–298 Background. The impact of oral conditions on quality of life of adolescents has not been thoroughly investigated. Aim. The purpose of this study was to assess the reliability and validity of an Albanian version of the oral impact of daily performance (OIDP) questionnaire. Design. A total of 493 adolescents attending secondary public schools in Albania attended clinical examination and completed a questionnaire that included an Albanian version of the OIDP inventory. The psychometric properties of the OIDP were evaluated in terms of reliability and validity. Results. The validity and reliability of the Albanian version of OIDP were good. Cohen’s Kappa ranged from 0.72 to 0.79. In terms of internal consistency, Cronbach’s alpha was 0.77. Construct and criterion validity were demonstrated in that the OIDP frequency scores were statistically significant with global measures of self‐rated and self‐perceived oral health status variables and some of the clinical variables used in this study. A total 60.9% of participants reported having at least one oral impact. The most prevalent impact was difficulty in smiling, whereas difficulty in speaking was less prevalent impact. Conclusion. The Albanian version of OIDP seems to be a reliable and valid scale for use in an urban adolescent population.  相似文献   
50.
Treatment of peri-implant osseous defects represents a significant challenge for clinicians, and the need to evolve within predictable surgical procedures is important. This case report describes the surgical treatment and grafting with porous titanium granules (PTG) of one patient with a peri-implant osseous defect. The suggested thrombogenic properties of titanium are intriguing from the perspective of osseous reconstructive surgery. In an ongoing randomized clinical trial using PTG for treatment of peri-implant osseous defects, one patient with one test implant was excluded and scheduled for implant removal. The surgical therapy included open flap debridement with surface decontamination with 24% EDTA gel, grafting with PTG, and resubmersion of the implant. After 12 months of healing, the implant with surrounding tissues was excised en bloc and micro CT and histological analyses were performed. Analyses showed PTG in close contact with new bone and with bone growing both into the porosities of the graft material and onto the adjacent implant surface. Element analysis demonstrated calcium and phosphorus in the new tissue embedding the PTG and the implant. Int J Oral Maxillofac Implants 2011;26:e9-e14.  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