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   8281篇
  免费   515篇
  国内免费   29篇
耳鼻咽喉   150篇
儿科学   248篇
妇产科学   189篇
基础医学   1363篇
口腔科学   177篇
临床医学   823篇
内科学   1525篇
皮肤病学   153篇
神经病学   823篇
特种医学   390篇
外科学   1213篇
综合类   36篇
一般理论   2篇
预防医学   482篇
眼科学   253篇
药学   504篇
中国医学   15篇
肿瘤学   479篇
  2023年   56篇
  2022年   100篇
  2021年   210篇
  2020年   112篇
  2019年   171篇
  2018年   201篇
  2017年   169篇
  2016年   223篇
  2015年   260篇
  2014年   322篇
  2013年   372篇
  2012年   589篇
  2011年   546篇
  2010年   348篇
  2009年   304篇
  2008年   444篇
  2007年   473篇
  2006年   500篇
  2005年   433篇
  2004年   390篇
  2003年   348篇
  2002年   316篇
  2001年   173篇
  2000年   134篇
  1999年   135篇
  1998年   93篇
  1997年   62篇
  1996年   35篇
  1995年   39篇
  1994年   33篇
  1993年   32篇
  1992年   84篇
  1991年   65篇
  1990年   86篇
  1989年   67篇
  1988年   56篇
  1987年   54篇
  1986年   48篇
  1985年   70篇
  1984年   40篇
  1983年   40篇
  1982年   48篇
  1979年   43篇
  1977年   26篇
  1975年   32篇
  1974年   32篇
  1973年   35篇
  1972年   32篇
  1971年   25篇
  1968年   25篇
排序方式: 共有8825条查询结果,搜索用时 15 毫秒
1.
2.
Microglia, the innate immune cells of the CNS, perform critical inflammatory and noninflammatory functions that maintain normal neural function. For example, microglia clear misfolded proteins, elaborate trophic factors, and regulate and terminate toxic inflammation. In Alzheimer’s disease (AD), however, beneficial microglial functions become impaired, accelerating synaptic and neuronal loss. Better understanding of the molecular mechanisms that contribute to microglial dysfunction is an important objective for identifying potential strategies to delay progression to AD. The inflammatory cyclooxygenase/prostaglandin E2 (COX/PGE2) pathway has been implicated in preclinical AD development, both in human epidemiology studies and in transgenic rodent models of AD. Here, we evaluated murine models that recapitulate microglial responses to Aβ peptides and determined that microglia-specific deletion of the gene encoding the PGE2 receptor EP2 restores microglial chemotaxis and Aβ clearance, suppresses toxic inflammation, increases cytoprotective insulin-like growth factor 1 (IGF1) signaling, and prevents synaptic injury and memory deficits. Our findings indicate that EP2 signaling suppresses beneficial microglia functions that falter during AD development and suggest that inhibition of the COX/PGE2/EP2 immune pathway has potential as a strategy to restore healthy microglial function and prevent progression to AD.  相似文献   
3.
The results of a controlled randomized and prospective clinical study including 113 patients from March 1987 until August 1988 showed that prophylactic drainage in elective resection for cancer of the colon was not necessary. 60 patients received a drain, 53 patients were not drained. The drain turned out to be ineffective even concerning its expected function of draining intraabdominal fluid: its diagnostic and therapeutic value failed in clinical practice. The rate of surgical complications--i.e. anastomotic leakage, impaired wound healing and relaparotomy--was significantly higher in the drained group. In elective colon resection the use of a drain as a routine procedure cannot be recommended.  相似文献   
4.

Hintergrund:  

Die nosokomiale Pneumonie gehört zu den häufigsten nosokomialen Infektionen und ist die häufigste auf der Intensivstation. Die nosokomiale Pneumonie ist mit einer signifikanten Mortalität und Morbidität assoziiert, und ihr Auftreten verschlechtert die Prognose des Patienten deutlich. Nach der Definition der DRGs auch im deutschen Krankenhaussystem ist die nosokomiale Pneumonie überwiegend Sache des Krankenhauses und kann somit nicht nur das Ergebnis der Patientenbehandlung, sondern auch das finanzielle Ergebnis des Krankenhauses beeinträchtigen.  相似文献   
5.
Molecular determinants of cetuximab efficacy.   总被引:17,自引:0,他引:17  
PURPOSE: To investigate whether mRNA expression levels of cyclin D1 (CCND1), cyclooxygenase 2 (Cox-2), epidermal growth factor receptor (EGFR), interleukin 8 (IL-8), and vascular endothelial growth factor (VEGF), all members of the EGFR signaling pathway, are associated with clinical outcome in patients with EGFR-expressing metastatic colorectal cancer (CRC) treated with cetuximab. PATIENTS AND METHODS: Thirty-nine patients with metastatic CRC, refractory to both irinotecan and oxaliplatin, were enrolled on IMCL-0144 and treated with single-agent cetuximab. The intratumoral mRNA levels of CCND1, Cox-2, EGFR, IL-8, and VEGF were assessed from paraffin-embedded tissue samples using laser-capture microdissection and quantitative real-time polymerase chain reaction. RESULTS: There were 21 women and 18 men with a median age of 64 years (range, 35 to 83 years). Higher gene expression levels of VEGF were associated with resistance to cetuximab (P = .038; Kruskal-Wallis test). The combination of low gene expression levels of Cox-2, EGFR, and IL-8 was significantly associated with overall survival (13.5 v 2.3 months; P = .028; log-rank test). Both findings were independent of skin toxicity that was itself significantly correlated to survival. Patients with a lower mRNA amount of EGFR had a longer overall survival compared with patients that had a higher mRNA amount (7.3 v 2.2 months; P = .09; log-rank test). Patients with lower expression of Cox-2 had a significantly higher rate of grade 2 to 3 skin reactions under cetuximab treatment. CONCLUSION: This pilot study suggests that gene expression levels of Cox-2, EGFR, IL-8, and VEGF in patients with metastatic CRC may be useful markers of clinical outcome in single-agent cetuximab treatment.  相似文献   
6.
Background and aims Since the introduction of endovascular aortic aneurysm repair (EVAR) for aortic aneurysms, the number of juxtarenal aortic aneurysms (JRA) has been growing steadily due to selection bias (neck morphology for EVAR). This case-match study compares the perioperative outcome and midterm results of suprarenally clamped JRA with infrarenal aortic aneurysms (AAA). Methods From 1997 to 2004, patients who received open surgery with suprarenal clamping for JRA were included in the study and compared to matched patients with infrarenal clamping (AAA). Measurements analyzed were the in-hospital mortality and morbidity. Midterm results were obtained through clinical investigation and magnetic resonance angiography imaging. Results Thirty-five patients (mean age, 68.4 years; 30 male and 5 female) received suprarenal cross-clamping for JRA. The overall in-hospital mortality for JRA and for the controls (AAA) with elective aortic repair was 4.5% (6.1% JRA; 3% AAA, p = 0.058). The morbidity of JRA was elevated according to the rate of pulmonary complications (p = 0.021) and the need for re-operation (p = 0.019). The mean follow-up time was 2.3 years (range, 8–96 months). At follow-up, 28 patients (80%) from the JRA group and 29 patients from the AAA group (82.9%) were alive. Conclusion Open aortic surgery for JRA with the need for suprarenal cross-clamping shows a slightly elevated in-hospital mortality rate without statistical significance and equal midterm mortality results in comparison with infrarenally clamped aortic aneurysms.  相似文献   
7.
8.
Anemia has a high prevalence in patients with cancer. Its frequency and severity depend on tumor type, tumor stage, duration of disease, and treatment status. The etiology of cancer-related anemia is multifactorial and includes myelotoxicity of treatment, bone marrow infiltration, impaired erythropoietin production, blood loss, and the anemia of chronic disease. Anemia affects health-related quality of life (QOL) and may impact on tolerance or even outcome of anticancer therapy. Despite its high prevalence and impact on QOL, anemia is often under-recognized and under-treated. Treatment should correct etiologic factors, whenever possible. Symptomatic treatments are red blood cell transfusions and administration of erythropoietic growth factors. Transfusions result in rapid improvement of anemia-related symptoms but are usually only given to patients with moderate to severe anemia. Administration of epoetins (epoetin alfa, epoetin beta) or darbepoetin alfa increases hemoglobin levels, reduces the need for blood transfusions, and improves QOL in patients with cancer-related anemia. Trials determining the exact association of anemia with both response to chemo(radio)therapy and survival are ongoing. Physicians should be aware of the clinical relevance of and treatment options for anemia in cancer patients.  相似文献   
9.
10.
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