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   1919篇
  免费   107篇
  国内免费   14篇
耳鼻咽喉   26篇
儿科学   127篇
妇产科学   128篇
基础医学   203篇
口腔科学   126篇
临床医学   127篇
内科学   301篇
皮肤病学   41篇
神经病学   133篇
特种医学   60篇
外科学   311篇
综合类   36篇
预防医学   56篇
眼科学   135篇
药学   68篇
中国医学   6篇
肿瘤学   156篇
  2023年   16篇
  2022年   20篇
  2021年   52篇
  2020年   33篇
  2019年   29篇
  2018年   56篇
  2017年   30篇
  2016年   61篇
  2015年   77篇
  2014年   89篇
  2013年   125篇
  2012年   173篇
  2011年   144篇
  2010年   81篇
  2009年   80篇
  2008年   154篇
  2007年   148篇
  2006年   141篇
  2005年   140篇
  2004年   111篇
  2003年   88篇
  2002年   83篇
  2001年   26篇
  2000年   14篇
  1999年   14篇
  1998年   11篇
  1997年   2篇
  1996年   6篇
  1995年   2篇
  1994年   2篇
  1993年   2篇
  1992年   3篇
  1991年   5篇
  1990年   6篇
  1989年   2篇
  1988年   1篇
  1986年   2篇
  1985年   2篇
  1983年   2篇
  1980年   1篇
  1979年   2篇
  1975年   1篇
  1971年   1篇
  1970年   1篇
  1967年   1篇
排序方式: 共有2040条查询结果,搜索用时 8 毫秒
1.
A survey of 2576 children aged two to nine years was carried out in Dhaka, Bangladesh, as part of a collaborative study to test the validity of a questionnaire (the Ten Questions) for screening severe childhood disabilities in community settings. Approximately 7% of the children were positive on the screen and this rate was slightly higher in boys than girls. The sensitivity, specificity and negative predictive value of the Ten Questions were perfect or nearly perfect for severe and moderate (serious) disabilities. The positive predictive value was only 22% for serious disabilities, but 70% of children classified as false positives were found to have mild disabilities or other conditions (such as ear infections) for which early detection and treatment could be beneficial. No major age or gender differences in the validity of the questionnaire were apparent, but this finding needs additional study and confirmation with studies based on larger samples. In general, the results indicate that the Ten Questions is a valid tool for screening serious disabilities in children and can potentially improve the efficiency of health services by reducing the number of children requiring attention from professionals. Future studies using the Ten Questions should foster greater attention to the dimensions of childhood disability as a public health problem in the less developed world.  相似文献   
2.
Over a five-year period, 197 hysterectomies were performed at King Khalid University Hospital (KKUH). Indications for the procedures vary from menstrual disorders and symptomatic fibroids to ovarian malignancy. The most common indication was found to be menorrhagia. Among multiple pre-operative indications, only the first listed major indication for hysterectomy was chosen. There were 145 abdominal and 52 vaginal hysterectomies and all were elective gynaecological procedures, majority of which were performed on women in their fourth and fifth decades of life. Verification of pre-operative diagnosis, when correlated with pathological findings, showed that some of the indications for the procedure deserve a more critical reappraisal. Since hysterectomy carries substantial economic and medical consequences, indications for undertaking the procedure deserve more careful scrutiny given the surgical and nonsurgical options that are currently available. There may be a need, therefore, to assess the appropriateness or otherwise of the use of hysterectomy in many of the patients in future.  相似文献   
3.
4.
5.
A 58-year-old postmenopausal woman with primary ovarian serous carcinoma presented with the syndrome of inappropriate antidiuresis (SIAD). Preoperative workup showed serum sodium level of 110 mEq/liter and antidiuretic hormone level of 3.3 pg/ml. The serum and urine osmolarity were 239 and 371, respectively. Antidiuretic hormone was demonstrated in tumor cells by immunohistochemistry. To the best of the authors’ knowledge, this represents the first case of SIAD due to primary ovarian tumor.  相似文献   
6.
7.
We investigated the in vitro activity of caspofungin compared to amphotericin B, fluconazole, and itraconazole against clinical strains of Candida spp. (n =239). Antifungal susceptibility tests were done in accordance with NCCLS M27-A2 microdilution method and the results were read after 24 and 48 h. In general, 24 h MIC readings were similar to those at 48 h for most isolates and all antifungal agents. Caspofungin was active against all species tested. Caspofungin MICs of Candida parapsilosis were slightly higher than those for other Candida spp. Caspofungin MIC (microg/ml) ranges at 24 h for C. albicans, C. glabrata, C tropicalis, C. parapsilosis, C kefyr, C krusei, C. lusitaniae, C. norvegensis, C. guilliermondii and C. lipolytica were 0.06-2, 0.125-2, 0.125-2, 1-4, 0.125-2, 1-2, 0.5-2, 0.5-1, 0.5-2 and 1-2, respectively. Eagle (paradoxical) effect was observed in 31 and 8% of the isolates at highest concentrations of caspofungin and itraconazole, respectively. The activity of caspofungin against fluconazole- and/or itraconazole-resistant isolates was similar to that detected for the susceptible ones. We conclude that caspofungin appears as a promising antifungal agent with enhanced activity against Candida, including the azole-resistant strains.  相似文献   
8.
Genotypic analysis was performed on 48 Mycobacterium tuberculosis complex strains collected from a hospital in Dhaka city. Deletion analysis showed that the isolates were all M. tuberculosis; 13 of them were found to be of the "ancestral" type, while 35 were of the "modern" type, indicating that both endemic (ancestral type) and epidemic (modern type) strains cause tuberculosis in Bangladesh. Genotyping based on the spoligotype and variable-number tandem repeats (VNTR) of mycobacterial interspersed repetitive units (MIRU) was also done. A total of 34 strains (71%) were grouped by spoligotyping into nine different clusters; the largest comprised 15 isolates of the Beijing genotype, whereas the remaining eight clusters consisted of two to five isolates. MIRU-VNTR typing detected 32 different patterns among 44 tested strains, and the 15 Beijing strains were further discriminated by MIRU-VNTR typing (7 distinct patterns for the 15 isolates). These results indicate that MIRU-VNTR typing, along with spoligotyping and deletion analysis, can be used effectively for molecular epidemiological studies to determine ongoing transmission clusters; to our knowledge, this is the first report about the type of strains prevailing in Bangladesh.  相似文献   
9.
Matrix metalloproteinases (MMPs) with collagenolytic and gelatinolytic activities are up-regulated in basal cell carcinoma. In the present study we demonstrate that the major collagenolytic enzyme detected is MMP-1 (interstitial collagenase) while gelatinolytic enzymes include both MMP-2 (72-kDa gelatinase A) and MMP-9 (92-kDa gelatinase B). Significant fractions of all three enzymes are present as active forms. In spite of the fact that high levels of gelatinolytic enzymes are present, the major fragmentation products resulting from digestion of intact type I collagen are the 1/4 and 3/4 fragments (products of MMP-1-mediated digestion). Thus, it appears that the gelatinolytic enzymes are not capable of degrading the collagen fragments as rapidly as they are produced. Since previous studies have demonstrated that interaction of interstitial fibroblasts with high molecular weight fragments of type I collagen leads to increased MMP production, the present results suggest a mechanism underlying altered function of stromal elements in the connective tissue adjacent to the growing neoplasm.  相似文献   
10.
Widal test in diagnosis of typhoid fever in Turkey   总被引:4,自引:0,他引:4  
We studied the value of the Widal tube agglutination test for the diagnosis of typhoid fever. The subjects were all adults >18 years of age and were divided into four groups: (i) 317 healthy blood donor controls, (ii) 31 bacteriologically confirmed patients with Salmonella enterica serotype Typhi, (iii) 21 patients with a clinical diagnosis of typhoid fever, and (iv) 41 febrile nontyphoid patients. Blood donor controls were screened with a slide agglutination test for the Salmonella enterica serotype Typhi O and H antigens, and positives were then tested with the Widal test. Acute- and convalescent-phase sera from patients in groups 2, 3, and 4 were obtained 7 to 10 days apart and tested by the Widal test. Using a cutoff of >or = 1/200 for the O antigen test performed on acute-phase serum gave a sensitivity of 52% and a specificity of 88% with a positive predictive value (PPV) of 76% and a negative predictive value (NPV) of 71%. This increased to 90% sensitivity and specificity with a PPV of 88% and an NPV of 93% when the convalescent-phase serum was tested. We concluded that O and H agglutinin titers of > or = 1/200 are of diagnostic significance. The Widal test is easy, inexpensive, and relatively noninvasive. It can be of diagnostic value when blood cultures are not available or practical. The results must be interpreted cautiously because of the low sensitivity of the test. The Widal test done on convalescent-phase serum gave more-reliable results with higher specificity and sensitivity.  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