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   28442篇
  免费   2043篇
  国内免费   487篇
耳鼻咽喉   573篇
儿科学   396篇
妇产科学   494篇
基础医学   4608篇
口腔科学   432篇
临床医学   2243篇
内科学   6040篇
皮肤病学   1046篇
神经病学   2134篇
特种医学   1844篇
外科学   3829篇
综合类   135篇
一般理论   6篇
预防医学   956篇
眼科学   752篇
药学   2587篇
中国医学   373篇
肿瘤学   2524篇
  2023年   130篇
  2022年   107篇
  2021年   803篇
  2020年   547篇
  2019年   765篇
  2018年   894篇
  2017年   769篇
  2016年   1172篇
  2015年   1617篇
  2014年   1808篇
  2013年   1991篇
  2012年   2882篇
  2011年   2750篇
  2010年   1748篇
  2009年   1402篇
  2008年   1860篇
  2007年   1690篇
  2006年   1484篇
  2005年   1328篇
  2004年   1068篇
  2003年   956篇
  2002年   848篇
  2001年   376篇
  2000年   375篇
  1999年   265篇
  1998年   128篇
  1997年   120篇
  1996年   75篇
  1995年   58篇
  1994年   48篇
  1993年   56篇
  1992年   69篇
  1991年   94篇
  1990年   52篇
  1989年   67篇
  1988年   69篇
  1987年   57篇
  1986年   42篇
  1985年   39篇
  1984年   25篇
  1983年   29篇
  1982年   22篇
  1981年   19篇
  1980年   23篇
  1979年   31篇
  1978年   29篇
  1977年   35篇
  1975年   17篇
  1974年   16篇
  1972年   16篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
3.
4.
PurposeTumor size and lymph node metastasis are important factors that contribute to the progression of breast cancer. We aimed to analyze the relationship between tumor size and lymph node metastasis molecular subtype and examine the effects of nodal metastasis on overall survival (OS).MethodsWe retrospectively reviewed the data of 16,552 patients who underwent breast surgery in Samsung Medical Center between 2000 and 2015. Information on tumor size (largest diameter of the invasive component), number of positive lymph nodes, and molecular subtype were obtained. We constructed a linear regression model to evaluate the relationship between tumor size and lymph node metastasis. To determine the effect of nodal metastasis on OS, we performed a Cox proportional regression analysis with Np/T (number of metastatic lymph nodes [n]/tumor size [cm]).ResultsThis study included 12,007 patients with a median follow-up of 62 months. The linear regression coefficients were 1.043 for luminal A, 1.024 for luminal B, 0.656 for HER2, and 0.435 for triple-negative breast cancer (TNBC) subtypes. No significant difference was observed in the coefficients between the luminal A and B subtypes (p = 0.797), while all other coefficients showed significant difference. After adjusting for other risk factors, the hazard ratio (HR) of Np/T for each subtype was significant for OS: luminal A (HR, 1.134; 95% confidence interval [CI], 1.097–1.171; p < 0.001), luminal B (HR, 1.049; 95% CI, 1.013–1.086; p = 0.007), HER2 (HR, 1.069; 95% CI, 1.014–1.126; p = 0.013), and TNBC (HR, 1.038; 95% CI, 1.01–1.067; p = 0.008).ConclusionThe incidence of lymph node metastasis differed according to molecular subtype. Luminal types have higher incidence of nodal metastasis than HER2 and TNBC. The HR of Np/T was highest in luminal A subtypes and lowest in TNBC subtypes.  相似文献   
5.
Zygomatic implant treatment is widely applied for severe maxillary atrophy to help rehabilitate the maxillary dentition. This retrospective study was performed to evaluate the actual radiographic bone–implant contact (rBIC) lengths of zygomatic implants. The records of 28 patients who underwent zygomatic implant surgery and subsequent follow-up examinations between August 2013 and September 2018 in the Department of Oral and Maxillofacial Surgery, Taipei Tzu Chi Hospital were reviewed. The surgeries were performed by a single surgeon using the same treatment protocol. All patients had a computed tomography scan at 1 year after the surgery. Using three-dimensional imaging software, an investigator measured the rBIC lengths of 66 implants and documented their clinical status. The implant survival rate was 100%. The mean rBIC length was significantly longer in male patients than in female patients (20.80 ± 5.88 mm versus 17.79 ± 6.34 mm; P = 0.028). The mean rBIC length of double zygomatic implants was significantly longer when compared to that of single implants (21.11 ± 6.23 mm versus 17.75 ± 5.85 mm; P = 0.027). This article is novel in reporting the exact rBIC lengths of zygomatic implants in a clinical setting. The results showed that zygomatic implants are a viable treatment modality for full-mouth rehabilitation.  相似文献   
6.
Erythema induratum of Bazin (EIB) is a form of tuberculid resulting from hypersensitivity to tuberculosis antigen. EIB occurs most commonly in middle‐aged women and is not typically seen in children. Here, we present a rare case of EIB, presenting as a chronic nodular panniculitis, in a 10‐year‐old Korean boy.  相似文献   
7.
BACKGROUND Helicobacter pylori(H.pylori)infection is known to prevent the occurrence of gastroesophageal reflux disease(GERD)by inducing gastric mucosal atrophy.However,little is known about the relationship between atrophic gastritis(AG)and GERD.AIM To confirm the inverse correlation between AG and the occurrence and severity of GERD.METHODS Individuals receiving health checkups who underwent upper gastrointestinal endoscopy at Seoul National University Healthcare System Gangnam Center were included.The grade of reflux esophagitis was evaluated according to the Los Angeles classification.Endoscopic AG(EAG)was categorized into six grades.Serologic AG(SAG)was defined as pepsinogen I≤70 ng/m L and pepsinogen I/II ratio≤3.0.The association between the extent of EAG and SAG and the occurrence and severity of GERD was evaluated using multivariate logistic regression analysis.RESULTS In total,4684 individuals with GERD were compared with 21901 healthy controls.In multivariate logistic regression analysis,advanced age,male sex,body mass index>23 kg/m2,presence of metabolic syndrome,current smoking,and alcohol consumption were associated with an increased risk of GERD.Seropositivity for H.pylori immunoglobulin G antibodies was associated with a decreased risk of GERD.There was an inverse correlation between the extent of EAG and occurrence of GERD:Odds ratio(OR),1.01[95%confidence interval(CI):0.90-1.14]in C1,0.87(0.78-0.97)in C2,0.71(0.62-0.80)in C3,0.52(0.44-0.61)in O1,0.37(0.29-0.48)in O2,and 0.28(0.18-0.43)in O3.Additionally,the extent of EAG showed an inverse correlation with the severity of GERD.The presence of SAG was correlated with a reduced risk of GERD(OR=0.49,95%CI:0.28-0.87,P=0.014).CONCLUSION The extent of EAG and SAG exhibited strong inverse relationships with the occurrence and severity of GERD.AG followed by H.pylori infection may be independently protect against GERD.  相似文献   
8.
The predictive role of noninvasive liver fibrosis scores on liver-related mortality in patients with chronic hepatitis B below 40 years of age remains unclarified. We examined the association of liver fibrosis scores with liver-related mortality in young (<40 years) and older adults with hepatitis B virus (HBV) infection. A cohort study was performed in 21,360 HBsAg-positive Korean adults without liver cirrhosis or liver cancer at baseline who were followed up for up to 18 years. The liver fibrosis scores were determined using the fibrosis-4 score (FIB-4) and aspartate transaminase to platelet ratio index (APRI). Patients’ vital status and cause of death were ascertained through the National Death Records. During a median follow-up of 10.2 years, 283 liver-related deaths were identified (liver-related mortality, 127.4/105 person-years). The liver fibrosis scores were significantly associated with increased risks of liver-related mortality; this association did not differ by age group (<40 vs. ≥40 years). The multivariable-adjusted hazard ratios with 95% confidence intervals for liver-related mortality comparing intermediate and high to low FIB-4 scores were 4.23 (1.99–9.00), and 15.16 (5.18–44.38), respectively, among individuals under 40, and 4.46 (3.03–6.56) and 22.47 (15.11–33.41), respectively, among older individuals. These associations were similar in analyses using APRI. In this cohort of HBsAg-positive individuals, the liver fibrosis scores were associated with increased risks of liver-related mortality in young and older adults. The liver fibrosis scores have a role in predicting liver mortality, even in young adults with HBV.  相似文献   
9.
10.
The prevalence of head and neck squamous cell carcinoma (HNSCC) has continued to rise for decades. However, drug resistance to chemotherapeutics and relapse, mediated by cancer stem cells (CSCs), remains a significant impediment in clinical oncology to achieve successful treatment. Therefore, we focused on analyzing CSCs in HNSCC and demonstrated the effect of melatonin (Mel) and verteporfin (VP) on SCC-25 cells. HNSCC CSCs were enriched in the reactive oxygen species-low state and in sphere-forming cultures. Combination treatment with Mel and VP decreased HNSCC viability and increased apoptosis without causing significant damage to normal cells. Sphere-forming ability and stem cell population were reduced by co-treatment with Mel and VP, while mitochondrial ROS level was increased by the treatment. Furthermore, the expression of mitophagy markers, parkin and PINK1, was significantly decreased in the co-treated cells. Mel and VP induced mitochondrial depolarization and inhibited mitochondrial function. Parkin/TOM20 was localized near the nucleus and formed clusters of mitochondria in the cells after treatment. Moreover, Mel and VP downregulated the expression of markers involved in epithelial-mesenchymal transition and metastasis. The migration capacity of cells was significantly decreased by co-treatment with Mel and VP, accompanied by the down-regulation of MMP-2 and MMP-9 expression. Taken together, these results indicate that co-treatment with Mel and VP induces mitochondrial dysfunction, resulting in the apoptosis of CSCs. Mel and VP could thus be further investigated as potential therapies for HNSCC through their action on CSCs.  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