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   137篇
  免费   11篇
儿科学   18篇
妇产科学   1篇
基础医学   24篇
口腔科学   19篇
临床医学   22篇
内科学   19篇
皮肤病学   1篇
神经病学   9篇
特种医学   7篇
外科学   6篇
综合类   5篇
预防医学   7篇
眼科学   2篇
药学   3篇
肿瘤学   5篇
  2022年   1篇
  2021年   7篇
  2020年   6篇
  2019年   1篇
  2018年   2篇
  2016年   4篇
  2015年   4篇
  2014年   3篇
  2013年   4篇
  2012年   1篇
  2010年   3篇
  2009年   1篇
  2008年   5篇
  2007年   7篇
  2006年   2篇
  2005年   6篇
  2004年   2篇
  2003年   3篇
  2002年   2篇
  2001年   1篇
  1999年   3篇
  1998年   4篇
  1997年   9篇
  1996年   8篇
  1995年   3篇
  1994年   4篇
  1993年   2篇
  1992年   1篇
  1991年   3篇
  1990年   2篇
  1989年   4篇
  1988年   6篇
  1987年   2篇
  1986年   2篇
  1985年   4篇
  1984年   2篇
  1983年   1篇
  1982年   2篇
  1981年   1篇
  1980年   6篇
  1978年   1篇
  1975年   1篇
  1974年   1篇
  1973年   2篇
  1972年   2篇
  1971年   2篇
  1967年   1篇
  1966年   2篇
  1963年   1篇
  1953年   1篇
排序方式: 共有148条查询结果,搜索用时 15 毫秒
31.
The association between dummy use and sudden infant death syndrome (SIDS) was investigated in 485 deaths due to SIDS in the postneonatal age group and compared with 1800 control infants. Parental interviews were completed in 87% of subjects. The prevalence of dummy use in New Zealand is low and varies within New Zealand. Dummy use in the two week period before death was less in cases of SIDS than in the last two weeks for controls (odds ratio (OR) 0.76, 95% confidence interval (CI) 0.57 to 1.02). Use of a dummy in the last sleep for cases of SIDS or in the nominated sleep for controls was significantly less in cases than controls (OR 0.44, 95% CI 0.26 to 0.73). The OR changed very little after controlling for a wide range of potential confounders. It is concluded that dummy use may protect against SIDS, but this observation needs to be repeated before dummies can be recommended for this purpose. If dummy sucking is protective then it is one of several factors that may explain the higher mortality from SIDS in New Zealand than in other countries, and may also explain in part the regional variation within New Zealand.  相似文献   
32.
The primary objective of this study was to assess the expression of MIB‐1 (Ki‐67) in tumour tissues from 808 patients with epithelial ovarian tumours. The second was to evaluate, whether MIB‐1 (Ki‐67) tissue expression levels correlate with clinicopathological parameters and prognosis of the disease. Using tissue arrays (TA), we analysed the MIB‐1 (Ki‐67) expression levels in tissues from 202 women with borderline ovarian tumours (BOT) (177 stage I, 5 stage II, 19 stage III, 1 stage IV) and 606 ovarian cancer (OC) patients (177 stage I, 64 stage II, 311 stage III, 54 stage IV). Using a 10% cut‐off level for MIB‐1 (Ki‐67) overexpression, 12% of the BOTs and 51% of the OCs were positive for MIB‐1 (Ki‐67) expression. The frequency of MIB‐1 (Ki‐67) expression‐positive OC increased with increasing FIGO stage (p = 0.003), increasing histological grade (p ≤ 0.0001), and a significantly different distribution of MIB‐1 (Ki‐67) positive and negative tumours were found in adenocarcinoma NOS, serous adenocarcinomas, mucinous adenocarcinomas, endometrioid adenocarcinomas, non‐epithelial and clear‐cell carcinomas (p = 0.016). Univariate Kaplan–Meier survival analysis performed on all OC cases showed a significant shorter disease specific survival in patients with positive MIB‐1 (Ki‐67) expression in the tumour tissue (p ≤ 0.0001). In a Cox survival analysis including 606 FIGO stages I to IV OC cases, FIGO stage (II vs I: HR = 3.00, 95% CI: 1.81–4.99, III–I: HR = 6.41, 95% CI: 3.90–10.50, IV vs I: HR = 12.69, 95% CI: 7.21–22); age at diagnosis pr.10 years (HR = 1.27, 95% CI: 1.15–1.40), residual tumour after surgery (HR = 1.95, 95% CI: 1.40–2.73) and MIB‐1 (Ki‐67) expression (HR = 1.31, 95% CI: 1.08–1.60) had a significant independent impact on survival. Histological grade (p = 0.14) and histological tumour type (p = 0.35) had no significant independent impact on survival. In conclusion, our results predict that an increased level of MIB‐1 (Ki‐67) expression in tumour tissue, points to a less favourable outcome for OC patients.  相似文献   
33.
A new variant of human growth hormone was recently found [Pavlu, B. & Gellerfors, P. (1993) Bioseparation 3, 257-265]. We report here the identification and the structural determination of this variant. The variant, which is formed during the expression of human growth hormone in Escherichia coli, was found to be more hydrophobic than rhGH as judged by its prolonged elution time by hydrophobic interaction chromatography. The rhGH hydrophobic variant (rhGH-HV) was isolated and subjected to trypsin digestion and RP-HPLC analysis, resulting in an altered retention time of one single tryptic peptide as compared to the corresponding fragment of rhGH. This tryptic peptide constitutes the C-terminus (aa 179-191) of hGH and contains one of the two disulfide bridges in hGH, viz. CySl82-Cys189. Amino acid sequences and composition analyses of the tryptic peptide from rhGH-HV (Tv18 + 19) and the corresponding tryptic peptide from rhGH (T18 + 19) were identical. Electrospray mass spectrometry (ES/MS) of Tv18 + 19 isolated from rhGH-HV revealed a monoisotopic mass increase of 32.7, as compared to T18 + 19 from rhGH. A synthetic T18 + 19 peptide having a trisulfide bridge between Cys182 and Cys189 showed identical fragments in ES/MS compared to Tv18 + 19 isolated from rhGH-HV, i.e. m/z 617.7 and 682.9. These fragments are formed through a unique cleavage in the trisulfide (Cysl82-SSS-Cys189) bridge not found in the corresponding T18 + 19 disulfide peptide. Furthermore, the synthetic Tv18 + 19 co-eluted in RP-HPLC with T18 + 19 isolated from rhGH-HV. Two-dimensional NMR spectroscopy of the synthetic T18 + 19 and Tv18 + 19 peptides were performed. Using these data all protons were assigned. The major chemical shift changes (δ§>0.05 ppm) observed were for the β-protons of Cys182 and Cys189 in Tv18 + 19 as compared to T18 + 19. CD spectroscopy data were also in agreement with the above results. Based on these physico-chemical data, rhGH-HV has been structurally defined as a trisulfide variant of rhGH. The receptor binding properties of rhGH-HV was studied by a biosensor device, BIAcoreTM. The binding capacity of rhGH-HV was similar to rhGH with a binding stoichiometry to the rhGHBP of 1:1.6 and 1:1.5, respectively, indicating that the trisulfide modification did not affect its receptor binding properties. © Munksgaard 1996.  相似文献   
34.
Complicated skin and skin structure infections (cSSSIs) and intra-abdominal infections (IAIs) are problematic due to decreasing therapeutic options available against multidrug-resistant pathogens common among these types of infections. A total of 2245 isolates from African and the Middle Eastern (AfME) countries were collected to determine in vitro activity for tigecycline and comparators during 2007–2012 as part of the Tigecycline Evaluation Surveillance Trial program. Tigecycline was launched in the AfME in 2007 and remains active against a wide range of targeted pathogens worldwide. Isolates were recovered from cSSSI (1990) and IAI (255) from 38 sites in 11 AfME countries. Staphylococcus aureus was the most common species from cSSSI (27.9%), and the methicillin-resistant S. aureus rate was 25%. Enterococcus spp. (7.1%) and Streptococcus agalactiae (2.9%) were other common Gram-positive pathogens represented. Enterobacter spp. (14.5%), Pseudomonas aeruginosa (13.9%), Escherichia coli (11.4%), Klebsiella spp. (10.9%), and Acinetobacter spp. (7.2 %) were the most common Gram-negative species collected. Tigecycline MIC90 values were 0.25 μg/mL against S. aureus. E. coli and Enterobacter spp. had tigecycline MIC90 values of 1 and 2 μg/mL, respectively. E. coli was the most frequently collected species from IAI (28.3%), followed by Klebsiella spp. (20.8%), Enterococcus spp. (11.8%), and Stenotrophomonas maltophilia (6.3%). Isolates collected from IAI had the following tigecycline MIC90 values: E. coli (1 μg/mL), Klebsiella spp. and other Enterobacteriaceae (2 μg/mL), Enterococcus spp. (0.25 μg/mL), and S. maltophilia (1 μg/mL). Tigecycline in vitro activity was observed against a broad spectrum of bacterial species, including strains resistant to other antimicrobial classes.  相似文献   
35.
36.
The utility of the Spanish WAIS-III was investigated by examining its reliability and validity among 100 Spanish-speaking participants. Results indicated that the internal consistency of the subtests was satisfactory, but inadequate for Letter Number Sequencing. Criterion validity was adequate. Convergent and discriminant validity results were generally similar to the North American normative sample. Paired sample t-tests suggested that the WAIS-III may underestimate ability when compared to the criterion measures that were utilized to assess validity. This study provides support for the use of the Spanish WAIS-III in urban Hispanic populations, but also suggests that caution be used when administering specific subtests, due to the nature of the Latin America alphabet and potential test bias.  相似文献   
37.
PURPOSE: To assess whether exposure to a 9.4 T static magnetic field during sodium imaging at 105.92 MHz affects human vital signs and cognitive function. MATERIALS AND METHODS: Measurements of human vital signs and cognitive ability made before and after exposure to a 9.4 T MR scanner and a mock scanner with no magnetic field are compared using a protocol approved by the U.S. Food and Drug Administration (FDA). RESULTS: Exposure to a 9.4 T static magnetic field during sodium imaging did not result in a statistically significant change in the vital signs or cognitive ability of healthy normal volunteers. CONCLUSION: Vital sign and cognitive ability measurements made before and after sodium imaging at 9.4 T suggest that performing human MRI at 105.92 MHz in a 9.4 T static magnetic field does not pose a health risk.  相似文献   
38.
39.
40.
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