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   27654篇
  免费   3200篇
  国内免费   625篇
耳鼻咽喉   435篇
儿科学   748篇
妇产科学   370篇
基础医学   1811篇
口腔科学   1723篇
临床医学   1490篇
内科学   4047篇
皮肤病学   293篇
神经病学   885篇
特种医学   775篇
外国民族医学   18篇
外科学   8375篇
综合类   2317篇
预防医学   1051篇
眼科学   407篇
药学   744篇
  8篇
中国医学   247篇
肿瘤学   5735篇
  2024年   5篇
  2023年   715篇
  2022年   685篇
  2021年   1283篇
  2020年   1510篇
  2019年   1500篇
  2018年   1437篇
  2017年   1341篇
  2016年   1221篇
  2015年   1315篇
  2014年   1983篇
  2013年   2017篇
  2012年   1407篇
  2011年   1555篇
  2010年   1136篇
  2009年   1217篇
  2008年   1359篇
  2007年   1209篇
  2006年   1090篇
  2005年   1002篇
  2004年   920篇
  2003年   796篇
  2002年   646篇
  2001年   545篇
  2000年   444篇
  1999年   400篇
  1998年   345篇
  1997年   298篇
  1996年   236篇
  1995年   217篇
  1994年   216篇
  1993年   153篇
  1992年   164篇
  1991年   147篇
  1990年   121篇
  1989年   109篇
  1988年   99篇
  1987年   79篇
  1986年   81篇
  1985年   77篇
  1984年   67篇
  1983年   49篇
  1982年   56篇
  1981年   46篇
  1980年   49篇
  1979年   38篇
  1978年   32篇
  1977年   19篇
  1976年   19篇
  1975年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Objective: Nucleolar organizer regions (NORs) are DNA coils that transcribe to ribosomal RNA. The NOR-associated protein, termed argyrophilic NOR (AgNOR), was visible within the nucleus by staining with silver nitrate examination via the light microscope. AgNOR counting is a proliferation marker and may help in the diagnosis and prognosis of various neoplastic lesions. Aneuploidy (abnormal DNA content) can predict the progression, survival and prognosis of the tumors. The aim of this study was to evaluate the role of AgNORs, DNA ploidy status, and total S-phase fraction (TSPF) as prognostic parameters in malignant salivary gland tumors (MSGTs). Methods: The current study is a retrospective study on a cohort of MSGTs (N=47), to assess AgNORs using Silver Nitrate stain, DNA index (DI), and TSPF using flow cytometry (FCM). Data including tumor size and site, lymphovascular invasion (LVI), lymph node metastasis (LNM) were collected. Results: The AgNORs count was statistically significant with MSGT type. DI was found to have a significant association with tumor site, tumor size and MSGT type. In addition, TSPF was found to be significantly associated with LVI. A moderate positive correlation was noted between AgNORs count and TSPF. LNM, tumor site, high AgNORs and low DI were all associated with short disease-free survival (DFS) and poor overall survival (OS). Conclusion: The present study revealed that high AgNORs count, DNA aneuploidy and TSPF had a poor influence on MSGTs prognosis.  相似文献   
2.
BackgroundDespite high rate of cure in acute promyelocytic leukemia (APL) in clinical trials, outcomes in real-world practice are dismal. We utilized National Cancer Database (NCDB) to explore utilization of multiagent therapy in APL and identify any disparities in treatment in real-world practices.Patients and MethodsNCDB categorizes use of systemic chemotherapy into single agent versus multiagent therapy. Some patients received hormonal therapy, immunotherapy, and unknown therapy; details of these treatments could not be ascertained. We therefore used multiple logistic regression analysis to evaluate effects of covariates on the probability of multiagent therapy use in 6678 patients.ResultsCompared to patients >60 years, patients aged 0 to 18 years (hazard ratio[HR] 3.2, 95% confidence interval [CI] 1.8-5.5, P< .0001), 19 to 40 years (HR 1.6, 95% CI 1.03-2.54, P= .03), and 41 to 60 years (HR 1.6, 95% CI 1.3-1.9, P< .0001) were more likely to receive multiagent therapy. Patients with Charlson comorbidity index (CCI) of 0 (HR 1.6, 95% CI 1.2-2.3, P= .001) and CCI of 1 (HR 1.4, 95% CI 1.0-1.9, P= .04) had a higher likelihood of receiving multiagent therapy than patients with CCI ≥ 3. Patients treated at academic cancer centers, compared to those treated at community cancer center (HR 0.5, 95% CI 0.3-0.7, P= .001), comprehensive community cancer center (HR 0.7, 95% CI 0.6-0.8, P< .0001), and integrated network cancer center (HR 0.8, 95% CI 0.6-0.9, P= .02) were more likely to be treated with multiagent therapy. Compared to the patients with private insurance, those with Medicaid had increased likelihood (HR 1.2, 95% CI 1.0-1.4, P= .04) whereas uninsured patients had a lower likelihood of receiving multiagent therapy (HR 0.6, 95% CI 0.5-0.8, P= .0005).ConclusionTo our knowledge, this study is the first and the largest scale analysis of treatment practices in APL in real-world practices. Our findings highlight significant disparities in treatment of APL based on age, insurance, and health-system factors.  相似文献   
3.
4.
BackgroundCurrently, the potential benefits of additional resection after positive proximal intraoperative frozen sections (IFS) in perihilar cholangiocarcinoma (pCCA) on residual disease and oncological outcome remain uncertain. Therefore, the aim of this study is to investigate the number of R0 resections after additional resection of a positive proximal IFS and the influence of additional resections on overall survival (OS) in patients with pCCA.Materials and methodsA retrospective, multicenter, matched case-control study was performed, including patients undergoing resection for pCCA between 2000 and 2019 at three tertiary centers. Primary outcome was the number of achieved ‘additional’ R0 resections. Secondary outcomes were OS, recurrence, severe morbidity and mortality.ResultsForty-four out of 328 patients undergoing resection for pCCA had a positive proximal IFS. An additional resection was performed in 35 out of 44 (79.5%) patients, which was negative in 24 (68.6%) patients. Nevertheless, seven out of these 24 patients were eventually classified as R1 resection due to other positive resection margins. Therefore, 17 (48.6%) patients could be classified as “true” R0 resection after additional resection. Ninety-day mortality after R1 resections was high (25%) and strongly influenced OS. After correction for 90-day mortality, median OS after negative additional resection was 33 months (95%CI:29.5–36.5) compared to 30 months (95%CI:24.4–35.6) after initial R1 (P = 0.875) and 46 months (95%CI:32.7–59.3) after initial R0 (P = 0.348).ConclusionThere were only 17 patients (out of a total of 328 patients) that potentially benefitted from routine IFS. Additional resection for a positive IFS leading to R0 resection was not associated with improved long-term survival.  相似文献   
5.

Background

Survival in cancer patients is associated with a multitude of biological, social, and psychological factors. Although it is well established that all these factors add to overall mortality, it is not well understood how the predictive power of these parameters changes in a comprehensive model and over time.

Methods

Patients who attended the authors’ outpatient clinic were invited to participate. The authors followed 5180 mixed cancer patients (51.1% female; mean age, 59.1 years [SD = 13.8]) for up to 16 years and analyzed biological (age, sex, cancer site, anemia), psychological (anxiety, depression), and social variables (marital status, education, employment status) potentially predicting overall survival in a Cox proportional hazards model.

Results

The median survival time for the entire sample was 4.3 years (95% confidence interval, 4.0–4.7). The overall survival probabilities for 1 and 10 years were 76.8% and 38.0%, respectively. Following an empirical approach, the authors split the time interval into five periods: acute, subacute, short-term, medium-term, and long-term. A complex pattern of variables predicted overall survival differently in the five periods. Biological parameters were important throughout most of the time, social parameters were either time-independent predictors or tended to be more important in the longer term. Of the psychological parameters, only depression was a significant predictor and lost its predictive power in the long-term.

Conclusions

The findings of this study allow the development of comprehensive patient-specific models of risk and resilience factors addressing biopsychosocial needs of cancer patients, paving the way for a personalized treatment plan that goes beyond biomedical cancer care.  相似文献   
6.
While Merkel cell carcinoma (MCC) of the head and neck is highly malignant, it remains poorly characterized due to its rarity. The purpose of this study was to examine prognostic factors for overall survival (OS) and disease-specific survival (DSS) in patients with MCC of the head and neck region. The Surveillance, Epidemiology and End Results registry was reviewed for patients diagnosed between 1984 and 2016 with histologically confirmed, primary MCC of the head and neck region. A total of 2818 patients met the inclusion criteria, with a median age at diagnosis of 77 years. At five and 10 years, respectively, the OS was 42.4% and 25.1% and the DSS was 67.9% and 64.1%. Multivariate Cox analysis indicated that predictors of decreased DSS included age at diagnosis ≥75 years, white race, increasing tumor spread, lymph node involvement and either the lip or the scalp/neck as a primary site. When adjusting for the aforementioned factors, tumor depth was not found to be a prognostic factor for DSS. We anticipate these results will help clinicians to counsel patients regarding expectations and potential prognosis.  相似文献   
7.
8.
目的:探讨中性粒细胞/淋巴细胞比值(neutrophil to lymphocyte ratio,NLR)和血小板/淋巴细胞比值(platelet to lymphocyte ratio,PLR)及其动态变化对非小细胞肺癌(non-small cell lung cancer,NSCLC)免疫治疗疗效和预后的影响。方法:回顾性分析2018年10月至2020年2月我院收治的所有接受过nivolumab治疗的NSCLC患者32例,收集免疫治疗前和2周期治疗后的NLR和PLR,应用Kaplan-Meier方法进行生存分析,单因素和Cox多因素分析NLR、PLR及其动态变化和各种临床特征与免疫治疗疗效和无进展生存期之间的关系。结果:两周期免疫治疗后,NLR2较NLR0显著下降,分别为(3.25±2.80)和(3.94±2.36)(P=0.034 9);PLR2同PLR0相比无显著变化,分别为(165.75±114.25)和(197.09±79.90)(P=0.122 0);单因素分析显示PFS与NLR0、NLR2、PLR0、PLR2、分期有关(P<0.05);多因素分析表明NLR0(P=0.011)、分期(P=0.029)是PFS的独立预测因素。结论:较高的NLR0与PLR0患者的PFS更短,NLR的动态变化与患者的免疫治疗疗效显著相关。因此,NLR与PLR是预测NSCLC免疫治疗疗效和预后的理想指标。  相似文献   
9.
目的 探讨CAD/CAM技术联合个性化预成型钛网及游离髂骨移植修复单侧下颌骨大型轮廓缺损的可行性及有效性。方法 选取四川大学华西口腔医院正颌及关节外科2015年11月—2019年12月的15例单侧下颌骨大型轮廓缺损的患者。采用基于逆向工程的计算机辅助设计/计算机辅助制作(CAD/CAM)技术,镜像重建患侧下颌骨轮廓并制作个性化预成型钛网,术中切取游离髂骨联合预制钛网经颌下植入于下颌骨缺损部位,其中2例患者同期行颏成形术矫正颏部偏斜。术后通过测量比较双侧下颌支及下颌体的长度及其三维角度评价下颌骨轮廓的对称性。结果 所有患者预后良好,对手术效果满意且无不良并发症,术后三维测量结果显示下颌骨轮廓对称性良好(P>0.05)。结论 利用CAD/CAM技术制作个性化预成型钛网联合髂骨移植修复单侧下颌骨大型轮廓缺损可行,效果良好。  相似文献   
10.

Background

Advanced low-grade ovarian carcinoma (LGOC) is difficult to treat. In several studies, high estrogen receptor (ER) protein expression was observed in patients with LGOC, which suggests that antihormonal therapy (AHT) is a treatment option. However, only a subgroup of patients respond to AHT, and this response cannot be adequately predicted by currently used immunohistochemistry (IHC). A possible explanation is that IHC only takes the ligand, but not the activity, of the whole signal transduction pathway (STP) into account. Therefore, in this study, the authors assessed whether functional STP activity can be an alternative tool to predict response to AHT in LGOC.

Methods

Tumor tissue samples were obtained from patients with primary or recurrent LGOC who subsequently received AHT. Histoscores of ER and progesterone receptor (PR) were determined. In addition, STP activity of the ER STP and of six other STPs known to play a role in ovarian cancer was assessed and compared with the STP activity of healthy postmenopausal fallopian tube epithelium.

Results

Patients who had normal ER STP activity had a progression-free survival (PFS) of 16.1 months. This was significantly shorter in patients who had low and very high ER STP activity, with a median PFS of 6.0 and 2.1 months, respectively (p < .001). Unlike ER histoscores, PR histoscores were strongly correlated to the ER STP activity and thus to PFS.

Conclusions

Aberrant low and very high functional ER STP activity and low PR histoscores in patients with LGOC indicate decreased response to AHT. ER IHC is not representative of functional ER STP activity and is not related to PFS.  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