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   171788篇
  免费   16859篇
  国内免费   7657篇
耳鼻咽喉   2342篇
儿科学   3857篇
妇产科学   2233篇
基础医学   30410篇
口腔科学   5437篇
临床医学   13725篇
内科学   22940篇
皮肤病学   4494篇
神经病学   9356篇
特种医学   3793篇
外国民族医学   120篇
外科学   15412篇
综合类   27025篇
现状与发展   48篇
预防医学   4949篇
眼科学   3552篇
药学   13277篇
  41篇
中国医学   5672篇
肿瘤学   27621篇
  2024年   139篇
  2023年   2392篇
  2022年   3086篇
  2021年   5980篇
  2020年   5753篇
  2019年   5521篇
  2018年   5671篇
  2017年   6073篇
  2016年   6402篇
  2015年   7205篇
  2014年   10602篇
  2013年   11562篇
  2012年   9965篇
  2011年   11155篇
  2010年   9183篇
  2009年   8787篇
  2008年   9210篇
  2007年   9463篇
  2006年   8587篇
  2005年   7854篇
  2004年   6962篇
  2003年   6031篇
  2002年   4966篇
  2001年   4247篇
  2000年   3492篇
  1999年   3040篇
  1998年   2502篇
  1997年   2422篇
  1996年   2087篇
  1995年   2121篇
  1994年   1865篇
  1993年   1554篇
  1992年   1262篇
  1991年   1196篇
  1990年   926篇
  1989年   867篇
  1988年   809篇
  1987年   646篇
  1986年   601篇
  1985年   786篇
  1984年   704篇
  1983年   491篇
  1982年   523篇
  1981年   411篇
  1980年   346篇
  1979年   257篇
  1978年   184篇
  1977年   138篇
  1976年   103篇
  1975年   41篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
91.
ObjectivesThe reduction of postoperative acute kidney injury in patients undergoing cardiopulmonary bypass surgery using an oxygen delivery-guided perfusion strategy (oxygen delivery strategy) for cardiopulmonary bypass management compared with a fixed flow perfusion (conventional strategy) remains controversial. The purpose of this study was to determine whether a oxygen delivery strategy would reduce the incidence of postoperative acute kidney injury in patients undergoing cardiopulmonary bypass surgery.MethodsWe randomly enrolled 300 patients undergoing cardiopulmonary bypass surgery. Patients were randomly assigned to a oxygen delivery strategy (maintaining a oxygen delivery index value >300 mL/min/m2 through pump flow adjustments during cardiopulmonary bypass) or a conventional strategy (a target pump flow was determined on the basis of the body surface area). The primary end point was the development of acute kidney injury. Secondary end points were the red blood cell transfusion rate and number of red blood cell units, intubation time, postoperative length of stay in the intensive care unit and the hospital, predischarge estimated glomerular filtration rate, and hospital mortality.ResultsAcute kidney injury occurred in 20 patients (14.6%) receiving the oxygen delivery strategy and in 42 patients (30.4%) receiving the conventional strategy (relative risk, 0.48; 95% confidence interval, 0.30-0.77; P = .002). The secondary end points were not significantly different between strategies. In a prespecified subgroup analysis of patients who had nadir hematocrit less than 23% or body surface area less than 1.40 m2, the oxygen delivery strategy seemed to be superior to the conventional strategy and the existence of quantitative interactions was suggested.ConclusionsAn oxygen delivery strategy for cardiopulmonary bypass management was superior to a conventional strategy with respect to preventing the development of acute kidney injury.  相似文献   
92.
目的:研究胸段食管鳞癌术后复发模式,为术后放疗靶区勾画提供参考。方法:回顾分析我院2012年7月至2017年5月收治术后复发的81例胸段食管鳞癌患者的临床资料,参照AJCC第八版食管癌分期,将第1-8M站定义为上中纵隔淋巴结区,8Lo、9、15站定义为下纵隔淋巴结区,16-20站定义为上腹部淋巴结区。标记患者的复发部位,并分析局部复发、区域复发和远处转移的模式。结果:中位复发时间为12个月(2~103个月)。6例(7.4%)患者发生单纯局部复发,64例(79.0%)患者发生区域复发,11例(13.6%)患者发生远处转移。区域淋巴结复发中最高危的复发区域为上中纵隔淋巴引流区,此区域包含了82.8%的复发淋巴结,其次为上腹部淋巴结引流区(13.6%)。11例患者发生上腹部淋巴结复发,其中10(90.9%)例为胸下段,7例(63.6%)患者术后分期≥Ⅲ_(b)期。结论:胸段食管鳞癌术后复发模式以区域淋巴结复发为主,上中纵隔淋巴引流区为最高危复发区域,术后放疗靶区应重点包含。对于术后分期较晚的胸下段食管鳞癌,上腹部淋巴结引流区可能需要涵盖在放疗靶区内。吻合口、瘤床和下纵隔复发风险低,可不必常规涵盖在放疗靶区内。  相似文献   
93.
In the United States, renal cell carcinoma (RCC) incidence and the prevalence of obesity, an established risk factor for RCC, have been increasing for several decades. RCC is more common among older individuals. We sought to quantify the contribution of excess adiposity to the rising incidence of RCC among individuals 60 years or older. National Institutes of Health-American Association of Retired Persons Diet and Health Study data (n = 453 859 participants, enrolled in 1995-1996, age at enrollment 50-71 years) were used to estimate multivariable-adjusted hazard ratios (HRs) for RCC across body mass index categories and HRs associated with smoking. Population attributable fractions (PAFs) were calculated using estimated HRs and annual overweight/obesity prevalence from the National Health Interview Survey (1985-2008). PAF estimates were combined with RCC incidence from Surveillance, Epidemiology and End Results-13 to calculate annual percent changes in RCC incidence attributable (and unrelated) to overweight/obesity. We found that between 1995 and 2018, among individuals aged 60 years and older, PAF for overweight/obesity increased from 18% to 29% for all RCCs. In comparison, the PAF for smoking declined from 12% to 9%. RCC incidence increased 1.8% per year (95% confidence interval [CI] 1.5%-2.1%) overall, while RCC incidence attributable to overweight/obesity increased 3.8% per year (95%CI 3.5%-4.2%) and RCC incidence unrelated to overweight/obesity increased 1.2% per year (95% CI 0.9%-1.4%). In conclusion, overweight/obesity appears to have contributed importantly to the rising incidence of RCC in the United States since the mid-1990s. Public health interventions focused on reducing overweight and obesity could help substantially in curbing this trend.  相似文献   
94.
95.
目的对玻切二期术后低视力人群采取特殊的护理策略,来平复病人的负面情绪,提高治疗满意度。方法对2019年11月6日至2020年11月6日在我院接受玻璃体切割二次手术的96名低视力患者进行特殊护理干预,然后进行回顾性分析。结果在结合实际病情分析采取的特殊护理策略干预下,病人术后情绪稳定,未出现不良投诉事件,满意度较高。结论对玻切二期术后低视力人群采取特殊的护理干预策略十分必要。  相似文献   
96.
97.
Cutaneous histiocytoses constitute a heterogeneous group of diseases characterised by the cutaneous accumulation of cells with the cytological and phenotypic features of macrophages or dendritic cells. The clinical spectrum ranges from self-resolving, skin-limited conditions to severe, multiorgan disease with a high morbidity rate. Until recently, cutaneous histiocytoses were classified according to the immunophenotype of the pathological cells, with differentiation between Langerhans cell histiocytosis (LCH) [CD1a+, CD207 (langerin)+] and non-Langerhans cell histiocytosis (CD68+, CD163+, CD1a?, CD207?). Over the last 12 years, a number of new pathophysiological findings (in particular, molecular pathology results) regarding histiocytoses have contributed to a new classification based on molecular alterations, as well as on clinical and imaging characteristics and the phenotype. The most frequent entities in children are juvenile xanthogranuloma and LCH.  相似文献   
98.
99.
The cryopreservation process of stem cells potentially cause the loss of CD34+ cells. The aim of this study is to evaluate association of patient, graft and technical characteristics with post cryopreserved CD34+ cells viability among lymphoproliferative disease namely multiple myeloma (MM) and lymphoma patients at Hospital Universiti Sains Malaysia (USM). This retrospective study was conducted in the Transplant Unit. A search of the hospital data (2008–2018) to identify 132 patients for both MM and lymphoma who underwent autologous peripheral blood haematopoietic stem cells (APBSC) mobilisation, and were successfully harvested and cryopreserved. Selected patients’ profile as well as selected parameters of stem cell mobilization and cryopreservation were obtained from laboratory information system (LIS), record unit and the Transplant Unit. Multiple logistic regression (MLR) was used to find significant associated factors and P < 0.05 was considered significant. The mean age of the patients was 39 years old with almost equal gender distribution and majority were lymphoma patients, 96 (72.7%) while 36 (27.3%) were multiple myeloma (MM) patients. The significant influencing factors of post-cryopreserved CD34+ cells viability were pre-cryopreserved CD34+ cell viability, total nucleated cells (TNC), and anti-platelet and antibiotics usage. Patients who are not on anti-platelet and have higher pre-cryopreserved CD34+ cells viability have higher chance for good post-cryopreserved CD34+ cells viability. While, those patients with higher TNC and on antibiotics have lower chance for good post cryopreserved CD34+ cells viability. This study showed patients who are not on anti-platelet and antibiotics will have higher probability of achieving good post cryopreserved CD34+ cells viability. The APBSC products with higher pre-cryopreserved CD34+ cells viability and lower TNC will achieve better post-cryopreserved CD34+ cells viability. The addition of extra plasma to the APBSC products is recommended to reduce the TNC.  相似文献   
100.
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