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   277840篇
  免费   17705篇
  国内免费   8656篇
耳鼻咽喉   2874篇
儿科学   8777篇
妇产科学   3167篇
基础医学   18836篇
口腔科学   4541篇
临床医学   31914篇
内科学   46149篇
皮肤病学   4031篇
神经病学   12908篇
特种医学   12724篇
外国民族医学   28篇
外科学   34485篇
综合类   26850篇
现状与发展   30篇
一般理论   3篇
预防医学   18007篇
眼科学   4968篇
药学   51935篇
  104篇
中国医学   7299篇
肿瘤学   14571篇
  2023年   2782篇
  2022年   6350篇
  2021年   12079篇
  2020年   7223篇
  2019年   13130篇
  2018年   7802篇
  2017年   7290篇
  2016年   9068篇
  2015年   11892篇
  2014年   21356篇
  2013年   21812篇
  2012年   22559篇
  2011年   19494篇
  2010年   17498篇
  2009年   16689篇
  2008年   15121篇
  2007年   15174篇
  2006年   12944篇
  2005年   9025篇
  2004年   5248篇
  2003年   4646篇
  2002年   3668篇
  2001年   3138篇
  2000年   2676篇
  1999年   1882篇
  1998年   2258篇
  1997年   2079篇
  1996年   1704篇
  1995年   1697篇
  1994年   1591篇
  1993年   1257篇
  1992年   1545篇
  1991年   1347篇
  1990年   1314篇
  1989年   1235篇
  1988年   1165篇
  1987年   1046篇
  1986年   841篇
  1985年   1759篇
  1984年   1874篇
  1983年   1364篇
  1982年   1432篇
  1981年   1397篇
  1980年   1192篇
  1979年   1030篇
  1978年   818篇
  1977年   802篇
  1976年   705篇
  1975年   474篇
  1974年   487篇
排序方式: 共有10000条查询结果,搜索用时 359 毫秒
131.
血吸虫病是一种严重危害人类健康、影响社会经济发展的重大传染病,为全球公共卫生负担和危害最严重的被忽视的热带病之一。吡喹酮是20世纪70年代研制出的一种高效、低毒、价廉的广谱抗蠕虫口服药,为世界卫生组织(WHO)推荐的抗血吸虫的首选药物。吡喹酮在血吸虫病流行区现场大规模反复使用已超过40年,血吸虫是否会对吡喹酮产生抗药性引起国际社会极大担忧,为学术界关注的热点科学问题。针对血吸虫病防治中这一重大需求,自1996年起, 在国家科技支撑计划、国家自然科学基金、江苏省自然科学基金等项目基金资助下,我们在血吸虫病流行区现场和实验室,对血吸虫在吡喹酮药物的压力是否会产生抗药性、抗性虫株的生物学特性、抗性的检测、吡喹酮抗性的交叉抗药性及抗药性的预防和控制等科学问题进行较为系统的研究,本文就其研究及其意义作一概述。  相似文献   
132.
Syphilis is a sexually transmitted disease caused by Treponema pallidum. Syphilitic aortitis might coexist in a dysfunctional aortic valve, but the etiology remains unclear, because microbiological diagnosis is difficult. A 62-year-old man with low-grade fever was diagnosed with aortitis and infective endocarditis, due to Treponema pallidum infection, using polymerase chain reaction analysis. This case suggests that syphilis might cause infective endocarditis.  相似文献   
133.
BackgroundConsiderable progress has been made in therapeutic options for multiple myeloma (MM). Understanding the current landscape of MM treatment options and associated outcomes in the real world is important in providing key insights into clinical and knowledge gaps which could be targeted for further optimization.MethodsThe Canadian Myeloma Research Group Database (CMRG-DB) is a prospectively maintained disease-specific database with >7000 patients. The objective of this study was to describe the trends in the treatment landscape and outcomes including early mortality, time to next treatment, and overall survival (OS) in each line of treatment stratified by autologous stem cell transplant (ASCT) receipt among newly-diagnosed MM patients in Canada between 2007 and 2018.ResultsA total of 5154 patients were identified among which 3030 patients (58.8%) received an upfront ASCT and 2124 (41.2%) did not. At diagnosis, the median age was 64 years and 58.6% were males. Bortezomib and lenalidomide were most frequently used (>50%) in first and second-line treatment respectively among both the ASCT and non-ASCT cohort. The median OS was 122.0 months (95% Cl 115.0-135.0 months) and 54.3 months (95% CI 50.8-58.8 months) for the ASCT and non-ASCT cohort respectively with an incremental decrease in OS in each subsequent line of treatment.ConclusionWe present the largest study to date in the Canadian landscape showing the characteristics, therapy usage, and outcomes among MM patients. This information will be critical in benchmarking current outcomes and provide key insight into areas of unmet needs and gaps for improvement of MM patients nationally.  相似文献   
134.
BackgroundAlthough there are robust data about the pathophysiology and prognostic implications of left ventricular (LV) systolic dysfunction in patients with acquired heart disease, similar prognostic data about LV systolic dysfunction are sparse in the tetralogy of Fallot (TOF) population. The purpose of this study was to perform a meta-analysis of all studies that assessed the relationship between LV ejection fraction (LVEF) and cardiovascular adverse events (CAEs) defined as death, aborted sudden death, or sustained ventricular tachycardia.MethodsWe used random-effects models to calculate hazard ratios (HRs) and 95% confidence intervals (CIs).ResultsOf the 1,809 citations, 7 studies with 2,854 patients (age 28 ± 4 years) were included. During 5.6 ± 3.4 years' follow-up, there were 82 deaths, 17 aborted sudden cardiac deaths, and 56 sustained ventricular tachycardia events. Overall, CAEs occurred in 5.1% (144 patients). As a continuous variable, LVEF was a predictor of CAE (HR 1.29, 95% CI, 1.09-1.53, P = 0.001) per 5% decrease in LVEF. Similarly, LVEF < 40% was also a predictor of CAE (HR 3.22, 95% CI, 2.16-4.80, P < 0.001).ConclusionsLV systolic dysfunction was an independent predictor of CAE, and we observed a 30% increase in the risk of CAE for every 5% decrease in LVEF, and a 3-fold increase in the risk of CAE in patients with LVEF <40% compared with other patients. These findings underscore the importance of incorporating LV systolic function in clinical risk stratification of patients with TOF and the need to explore new treatment options to address this problem.  相似文献   
135.
Understanding why persons with human immunodeficiency virus (HIV) have accelerated atherosclerosis and its sequelae, including coronary artery disease (CAD) and myocardial infarction, is necessary to provide appropriate care to a large and aging population with HIV. In this review, we delineate the diverse pathophysiologies underlying HIV-associated CAD and discuss how these are implicated in the clinical manifestations of CAD among persons with HIV. Several factors contribute to HIV-associated CAD, with chronic inflammation and immune activation likely representing the primary drivers. Increased monocyte activation, inflammation, and hyperlipidemia present in chronic HIV infection also mirror the pathophysiology of plaque rupture. Furthermore, mechanisms central to plaque erosion, such as activation of toll-like receptor 2 and formation of neutrophil extracellular traps, are also abundant in HIV. In addition to inflammation and immune activation in general, persons with HIV have a higher prevalence than uninfected persons of traditional cardiovascular risk factors, including dyslipidemia, hypertension, insulin resistance, and tobacco use. Antiretroviral therapies, although clearly necessary for HIV treatment and survival, have had varied effects on CAD, but newer generation regimens have reduced cardiovascular toxicities. From a clinical standpoint, this mix of risk factors is implicated in earlier CAD among persons with HIV than uninfected persons; whether the distribution and underlying plaque content of CAD for persons with HIV differs considerably from uninfected persons has not been definitively studied. Furthermore, the role of cardiovascular risk estimators in HIV remains unclear, as does the role of traditional and emerging therapies; no trials of CAD therapies powered to detect clinical events have been completed among persons with HIV.  相似文献   
136.
137.
It is hypothesized that persons who use drugs (PWUD) in Vietnam who are also HIV-positive may face additional challenges in psychosocial outcomes, and these challenges may extend to their family members. In this study, we examined depressive symptoms, stigma, social support, and caregiver burden of HIV-positive PWUD and their family members, compared to the outcomes of HIV-negative PWUD and their family members. Baseline, 3-month, and 6-month assessment data were gathered from 83 PWUD and 83 family members recruited from four communes in Phú Th? Province, Vietnam. For PWUD, although we observed a general decline in overall stigma over time for both groups, HIV-positive PWUD consistently reported significantly higher overall stigma for all three periods. Depressive symptoms among family members in both groups declined over time; however, family members of HIV-positive PWUD reported higher depressive symptoms across all three periods. In addition, family members of HIV-positive PWUD reported lower levels of tangible support across all three periods. Caregiver burden among family members of HIV-positive PWUD increased significantly over time, whereas the reported burden among family members of HIV-negative PWUD remained relatively unchanged. The findings highlight the need for future interventions for PWUD and family members, with targeted and culturally specific strategies to focus on the importance of addressing additional stigma experienced by PWUD who are HIV-positive. Such challenges may have direct negative impact on their family members' depressive symptoms, tangible support, and caregiver burden.  相似文献   
138.
The Impella 5.0, a percutaneously inserted left ventricular assist device, has been used to support patients who have severe heart failure or who are undergoing high-risk percutaneous coronary intervention. We report our surgical placement of the Impella 5.0, through a graft sewn to the aorta, to unload the left ventricle of a 59-year-old man who was undergoing venoarterial extracorporeal membrane oxygenation for postcardiotomy shock. The patient underwent successful placement of a long-term left ventricular assist device before his discharge from the hospital. The versatility of the Impella 5.0 is exemplified in this patient who was successfully bridged to long-term support.  相似文献   
139.
摘要 目的 验证丹参二萜醌类活性成分对胰腺癌和多发性骨髓瘤的抑制效应,阐明其诱导胰腺癌和多发性骨髓瘤凋亡的作用机制。方法 胰腺癌细胞AsPC-1、BxPC-3用含10% gibco胎牛血清的RPMI1640培养液培养,按隐丹参酮组(30μM)、丹参新酮组(15μM)、去氢丹参新酮组(15μM)分别加药处理。cell-counting-kit-8(CCK8)法检测细胞存活率;AnnexinⅤ-FITC/PI流式细胞术检测细胞凋亡;Western Blot检测相关PKC同工酶磷酸化水平;对AsPC-1和BxPC-3细胞进行siRNA转染,Western Blot检测相关PKC同工酶磷酸化水平。结果 隐丹参酮组AsPC-1、BxPC-3细胞存活率分别为40.1%±5.0%、36.2%±5.4%;丹参新酮组AsPC-1、BxPC-3细胞存活率分别为52.1%±5.1%、47.2%±5.7%;去氢丹参新组AsPC-1、BxPC-3细胞存活率分别为46.1%±5.0%、42.2%±5.4%(P<0.01)。流式细胞术结果显示:AsPC-1组内空白对照组、隐丹参酮组、丹参新酮组、去氢丹参新酮组细胞的凋亡率分别为4.71%、30.10%、52.26%、42.30%;BxPC-3组内空白对照组、隐丹参酮组、丹参新酮组、去氢丹参新酮组细胞的凋亡率分别为5.10%、30.66%、33.76%、51.76%(P<0.01)。Western Blot检测显示隐丹参酮组、丹参新酮组、去氢丹参新酮组较空白对照组,胰腺癌AsPC-1、BxPC-3细胞p-PKD/PKCμ ser916、p-PKCδ thr505、p-PKD/PKCμ ser744/748的水平降低。Western Blot检测显示,siRNA沉默胰腺癌AsPC-1、BxPC-3细胞PKCδ,胰腺癌AsPC-1、BxPC-3细胞PKD/PKCμ ser744/748的磷酸化水平下调。结论 隐丹参酮、丹参新酮、去氢丹参新酮通过抑制PKCδthr505的磷酸化水平,继而PKD1μser744/748磷酸化水平下调,从而显著促进胰腺癌AsPC-1和BxPC-3细胞凋亡发生。  相似文献   
140.
Myelofibrosis (MF) is a BCR-ABL1 myeloproliferative neoplasm that arises from hematopoietic stem and progenitor cells frequently harboring a somatic driver mutation in 1 of 3 genes: JAK2, CALR, or MPL. The pathologic features of this hematologic malignancy include myeloproliferation, diffuse bone marrow fibrosis, and overactivation of the JAK-STAT pathway, resulting in enhanced inflammatory cytokine release. The common clinical manifestations of MF include systemic symptoms, abnormal peripheral blood count levels, and splenomegaly. However, it has become increasingly appreciated that significant clinical heterogeneity exists among patients with MF. Two distinct MF clinical phenotypes include the myeloproliferative and myelodepletive phenotype, with peripheral blood counts being the main discerning feature. Patients with the myeloproliferative phenotype will present with elevated peripheral blood counts and often experience significant constitutional symptoms and progressive splenomegaly. In contrast, patients with the myelodepletive phenotype will have low peripheral blood counts and will frequently require transfusion support. Current frontline therapies for MF, include ruxolitinib and fedratinib, which can exacerbate cytopenias and thereby pose an impediment to effective treatment of the myelodepletive patient. The present review discusses the clinical and prognostic implications of the myelodepletive phenotype and the therapeutic options and limitations for this subset of patients, representing an unmet clinical need.  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