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   10124篇
  免费   587篇
  国内免费   179篇
耳鼻咽喉   163篇
儿科学   112篇
妇产科学   116篇
基础医学   1579篇
口腔科学   228篇
临床医学   776篇
内科学   2066篇
皮肤病学   374篇
神经病学   627篇
特种医学   540篇
外科学   1496篇
综合类   52篇
一般理论   3篇
预防医学   393篇
眼科学   211篇
药学   920篇
  2篇
中国医学   143篇
肿瘤学   1089篇
  2024年   30篇
  2023年   99篇
  2022年   238篇
  2021年   423篇
  2020年   161篇
  2019年   272篇
  2018年   304篇
  2017年   235篇
  2016年   385篇
  2015年   472篇
  2014年   547篇
  2013年   563篇
  2012年   891篇
  2011年   800篇
  2010年   493篇
  2009年   400篇
  2008年   580篇
  2007年   580篇
  2006年   487篇
  2005年   479篇
  2004年   380篇
  2003年   323篇
  2002年   249篇
  2001年   264篇
  2000年   227篇
  1999年   161篇
  1998年   94篇
  1997年   65篇
  1996年   54篇
  1995年   69篇
  1994年   59篇
  1993年   43篇
  1992年   81篇
  1991年   60篇
  1990年   50篇
  1989年   44篇
  1988年   45篇
  1987年   34篇
  1986年   29篇
  1985年   24篇
  1984年   9篇
  1983年   10篇
  1981年   6篇
  1980年   7篇
  1979年   8篇
  1978年   7篇
  1977年   6篇
  1976年   9篇
  1973年   6篇
  1968年   6篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
23.
24.
Wu  Zhen-Yu  Han  Hyun Ho  Kim  Hee Jeong  Lee  Jong Won  Chung  Il Yong  Kim  Jisun  Lee  Sae Byul  Son  Byung-Ho  Eom  Jin Sup  Jung  Jae Ho  Kim  Sung- Bae  Gong  Gyungyub  Kim  Hak Hee  Ahn  Sei -Hyun  Ko  BeomSeok 《Breast cancer research and treatment》2021,187(2):417-425
Breast Cancer Research and Treatment - We compared oncologic outcomes between breast cancer patients who underwent immediate implant-based breast reconstruction (IBBR) and those who underwent...  相似文献   
25.
26.
Objective:To evaluate the three-dimensional (3D) perioral soft tissue changes after orthodontic treatment in patients with dentoalveolar protrusion using structured light–based scanners.Materials and Methods:Forty-four Korean adults (19 men and 25 women, 21.4 ± 3.4 years) with dentoalveolar protrusion treated by extraction of all four first premolars and then en masse retraction with maximum anchorage were evaluated. Lateral cephalograms and 3D facial scans were obtained before treatment (T1) and immediately after debonding (T2). Superimposition was performed, and 27 perioral landmarks were identified. The 3D changes in the landmarks and ratio of movement of the soft tissue relative to the horizontal incisal tip were evaluated. A paired t-test and one-way analysis of variance were performed.Results:The upper incisors were retracted 5.76 mm and the lower incisors were retracted 4.62 mm (P < .001). The upper lip moved inferoposteriorly, and the lower lip moved superoposteriorly. In the lower lip, upward movement was greater than backward movement (P < .001). The most prominent changes appeared at the greatest bulge area. The relative ratios were 42%–53% in the upper lip area and 22%–82% in the lower lip area. The lip corners moved superoposteriorly (P < .001). Subnasale moved downward (P < .05) and posteriorly (P < .001), while the landmarks under the nostrils moved upward and posteriorly (P < .001).Conclusion:Facial scans from white structured light scanners efficiently evaluated 3D perioral soft tissue in dentoalveolar protrusion patients. Backward movement and significant vertical movement of the lip were observed. The nasal and lip angle areas showed considerable changes.  相似文献   
27.
AIMS: We have previously reported that lower doses of hormone therapy (L-HT) and tibolone have different effects on markers of cardiovascular disease when compared with conventional doses of HT. The objective was to compare the effects of L-HT and tibolone on lipid profile, vasodilation, and factors associated with inflammation and haemostasis. METHODS AND RESULTS: Forty-one women received a combination of micronized progesterone 100 mg with conjugated equine estrogen 0.3 mg vs. tibolone 2.5 mg alone daily in random order during 2 months with 2 months washout period. When compared with L-HT, tibolone significantly reduced total cholesterol (P<0.001), triglyceride (P<0.001), HDL cholesterol (P<0.001) levels, and triglyceride/HDL cholesterol ratios (P=0.004) except total cholesterol/HDL cholesterol ratios. Tibolone improved flow-mediated response to hyperaemia from baseline values (P<0.001) by a similar magnitude to L-HT. L-HT and tibolone did not increase high-sensitivity C-reactive protein relative to baseline values. L-HT reduced antithrombin III from baseline values (P=0.037), compared with tibolone showing no changes. However, there was no difference between either. In contrast, tibolone increased pro-thrombin fragment 1+2 (F1+2) from baseline values (P=0.002), compared with L-HT showing no changes. Tibolone significantly reduced plasma plasminogen activator inhibitor type 1 (PAI-1) antigen levels from baseline values (P=0.004), compared with L-HT showing no changes. The effects of L-HT and tibolone on F1+2 and PAI-1 were significantly different (P=0.045 and P=0.008, respectively). CONCLUSION: Both tibolone and L-HT improved flow-mediated response by a similar magnitude and did not significantly increase high-sensitivity C-reactive protein. However, tibolone significantly reduced PAI-1, but increased F1+2 more than L-HT.  相似文献   
28.
目的:间充质干细胞具有强大的增殖能力和多向分化潜能,文章对其主要的来源途径予以综述。资料来源:应用计算机检索Medline1991-01/2006-01期间的相关文章,检索词为“mesenchyma stem cells,origin,research progress”,并限定文章语言种类为English。同时计算机检索中国期刊全文数据库1998-01/2006-10期间的相关文章,检索词为“间充质干细胞,来源,研究进展”,并限定文章语言种类为中文。资料选择:对资料进行初审,并查看每篇文献后的引文。纳入标准:①间充质干细胞的起源。②间充质干细胞研究进展、干细胞的分离及鉴定。排除标准:重复研究、个案报告或Meta分析类文章。资料提炼:共收集到96篇相关文献,40篇文献符合纳入标准,排除的56篇文献为内容陈旧或重复。符合纳入标准的40篇文献中,分别涉及骨髓、肌肉、脐血、胎盘、外周血、脂肪组织、血管及其他来源的间充质干细胞。资料综合:间充质干细胞是属于中胚层的一类多能干细胞,具有强大的增殖能力和多向分化潜能,动物模型试验和临床应用研究也取得了一定的效果。间充质干细胞来源广泛,易于获得,临床上为神经损伤及其他系统的损伤修复提供了更为广泛的途径。结论:间充质干细胞主要来源于骨髓、肌肉、脐血、外周血、胎盘等组织,具有广阔的应用前景。  相似文献   
29.

Purpose:

To determine whether peritumoral hypointensity seen on hepatobiliary phase images of preoperative gadoxetate disodium‐enhanced magnetic resonance imaging (EOB‐MRI) is useful for predicting microvascular invasion of hepatocellular carcinoma (HCC).

Materials and Methods:

This study was approved by the Institutional Review Board. In all, 104 HCC masses in 104 patients who had undergone EOB‐MRI and liver surgery within 1 month after EOB‐MRI were evaluated. Two radiologists independently recorded the presence of a peritumoral hypointensity on hepatobiliary phase. Interobserver agreement was assessed and consensus records were used. Tumor size was measured. A chi‐square test and independent t‐test were used for univariate analysis. Multiple logistic regression was performed to determine factors for predicting microvascular invasion. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of peritumoral hypointensity were calculated.

Results:

Sixty HCCs had microvascular invasion and 44 did not. Interobserver agreement in determining peritumoral hypointensity was excellent (κ = 0.83). By univariate analysis, peritumoral hypointensity and tumor size were significant for predicting microvascular invasion of HCC. On multiple logistic regression analysis, only peritumoral hypointensity was significant in predicting microvascular invasion of HCC (P = 0.013). The sensitivity, specificity, PPV, and NPV of peritumoral hypointensity were 38.3%, 93.2%, 88.5%, and 52.6%, respectively.

Conclusion:

Peritumoral hypointensity on the hepatobiliary phase of EOB‐MRI is not sensitive but has high specificity for predicting microvascular invasion of HCC. J. Magn. Reson. Imaging 2012;35:629‐634. © 2011 Wiley Periodicals, Inc.  相似文献   
30.
Cho YM  Park KS  Jung HS  Jeon HJ  Ahn C  Ha J  Kim SJ  Rhee BD  Kim SY  Lee HK 《Diabetes care》2003,26(4):1123-1128
OBJECTIVE: The incidence of posttransplantation diabetes mellitus (PTDM) has been reported to vary according to different study populations or different definitions. In this study, using American Diabetes Association criteria, the incidence and clinical characteristics of PTDM in Korean renal allograft recipients undergoing tacrolimus-based immunosuppression were examined. RESEARCH DESIGN AND METHODS: A total of 21 patients taking tacrolimus as primary immunosuppressant were recruited and tested with a serial 75-g oral glucose tolerance test at 0, 1, 3, and 6 months after renal transplantation. RESULTS: The cumulative incidence of PTDM was 52.4% at 1 month and 57.1% at 3 and 6 months. The baseline characteristics of the PTDM group were old age (especially >40 years), a high BMI, a high fasting glucose level, a high plasma insulin level, and increased insulin resistance. Among these parameters, old age was the only independent risk factor. The insulin secretory capacity in the PTDM group was maximally suppressed 3 months after transplantation. Thereafter, it was gradually restored along with dose reduction of tacrolimus. CONCLUSIONS: Routine screening for PTDM is necessary in patients over 40 years of age who are undergoing a relatively higher dose tacrolimus therapy during the early course of postrenal transplantation.  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