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   8972篇
  免费   406篇
  国内免费   96篇
耳鼻咽喉   87篇
儿科学   191篇
妇产科学   401篇
基础医学   756篇
口腔科学   64篇
临床医学   702篇
内科学   2883篇
皮肤病学   148篇
神经病学   446篇
特种医学   163篇
外科学   990篇
综合类   478篇
现状与发展   1篇
预防医学   1119篇
眼科学   113篇
药学   683篇
  2篇
中国医学   70篇
肿瘤学   177篇
  2023年   179篇
  2022年   322篇
  2021年   303篇
  2020年   310篇
  2019年   847篇
  2018年   900篇
  2017年   273篇
  2016年   161篇
  2015年   167篇
  2014年   561篇
  2013年   492篇
  2012年   495篇
  2011年   500篇
  2010年   336篇
  2009年   330篇
  2008年   333篇
  2007年   319篇
  2006年   277篇
  2005年   299篇
  2004年   265篇
  2003年   197篇
  2002年   117篇
  2001年   96篇
  2000年   55篇
  1999年   92篇
  1998年   54篇
  1997年   72篇
  1996年   65篇
  1995年   51篇
  1994年   63篇
  1993年   56篇
  1992年   53篇
  1991年   47篇
  1990年   33篇
  1989年   58篇
  1988年   59篇
  1987年   56篇
  1986年   55篇
  1985年   59篇
  1984年   70篇
  1983年   57篇
  1982年   48篇
  1981年   58篇
  1980年   41篇
  1979年   31篇
  1978年   28篇
  1977年   21篇
  1976年   20篇
  1974年   26篇
  1973年   18篇
排序方式: 共有9474条查询结果,搜索用时 32 毫秒
981.
BackgroundOxidative stress increases oxidizability of apolipoprotein-B containing lipoproteins and decreases paraoxonase (PON) activity in hemodialysis (HD) patients and plays an important part in the development of atherosclerotic cardiovascular diseases. In HD patients, plasma ascorbic acid (AA) levels are decreased either due to the loss by hemodialysis membranes or due to malnutrition and contribute to the imbalance of antioxidant defense mechanisms. We hypothesized that long-term ascorbic acid (AA) supplementation recovers oxidizability of lipoproteins in HD patients by reinforcing PON activity.MethodsTwenty-nine adult patients were treated with 100 mg and 500 mg AA at the end of each HD session thrice a week for two consecutive 16 weeks-periods, respectively. Blood samples were obtained before the first HD session and prior to the first HD sessions following the 100 mg AA-supplemented and the 500 mg AA-supplemented periods.ResultsPON activities were significantly increased after 100 mg (p < 0.05) and 500 mg AA (p < 0.001) supplementation periods compared to the basal level. Apo-B lipoprotein oxidizability (Δ-MDA) was significantly decreased after 500 mg AA supplementation compared to both basal (p < 0.05) and 100 mg AA supplementation periods (p < 0.05). Plasma AA concentrations were negatively correlated with Δ-MDA levels (R = −0.327; p < 0.01).ConclusionOur results suggest that long-term parenteral 500 mg AA supplementation improves PON activity alleviating apo B-containing lipoproteins oxidizability in HD patients.  相似文献   
982.
IntroductionThe pandemic caused by SARS-CoV-2 has drastically changed the global health landscape. Our objective was to verify if, after the start of the pandemic, there was an increase in in-hospital mortality in patients admitted to a Gastroenterology Service of a 3rd level hospital.Material and methodsThe 1039 admissions registered at the Virgen de la Victoria University Hospital in Malaga (Spain) were retrospectively analysed in the period between 1 December 2019 and 30 November 2020 (12 months), which were divided into 4 quarters (pre-wave, first wave, inter-wave and second wave) and mortality and other variables (globally and by disease group) were analysed.ResultsNo statistically significant differences were observed in terms of overall in-hospital mortality in the different periods. (p 0.23). The greatest burden of disease corresponded to biliopancreatic group and, within them, acute pancreatitis (p 0.04), followed by non-variceal gastrointestinal bleeding. In the second semester, mortality increased in the biliopancreatic group (p 0.01). Patients admitted for gastrointestinal bleeding took longer to request care after the start of the pandemic, especially in the second wave (p 0.03). The same was observed in admissions due to tumours, with the time elapsed until the emergency visit more than double in the second semester, with a consequent increase in mortality (p 0.00).ConclusionsThe global in-hospital mortality in a Gastroenterology Service in a 3rd level hospital has not increased with the onset of the SARS-CoV-2 pandemic, however, a higher in-hospital mortality has been recorded in biliopancreatic diseases and digestive tumours diagnosed on an in-patient basis between June and November 2020.  相似文献   
983.
ObjectivesAlthough the association between genetic factors, such as RNF213 mutations, and moyamoya disease (MMD) has been well investigated, environmental factors are largely undetermined. Thus, we aimed to examine whether viral infection increases the risk of MMD.Materials and MethodsTo eliminate the effect of presence or absence of the RNF213 p.R4810K mutation, the entire study population was positive for this mutation. We collected whole blood from 111 patients with MMD (45 familial and 66 sporadic cases) and 67 healthy volunteers, and we measured the immunoglobulin G titer of 11 viruses (cytomegalovirus, varicella-zoster virus, measles virus, rubella virus, herpes simplex virus, mumps virus, Epstein–Barr virus, human parvovirus B19, human herpesvirus 6 [HHV6], human herpesvirus 8, and John Cunningham virus) that were presumed to be associated with vasculopathy using the enzyme-linked immunosorbent assay. Positivity for past viral infection was determined by cut-off values obtained from previous reports and the manufacturer's instructions, and the positive rate was compared between cases and age- and sex-matched controls. We performed familial case-specific and sporadic case-specific analyses, as well as a case–control analysis.ResultsThere was no significant difference in the positive rate between the case group and the control group in any of the analyses. A significant difference was only observed in the combined case–control analysis for HHV6 (p = 0.046), but the viral antibody-positive rate in control individuals was higher than in MMD cases.ConclusionsOur cross-sectional study suggest that the investigated 11 viruses including HHV6 are unlikely to have an impact on MMD development.  相似文献   
984.
Fetal gastroschisis is the most common congenital malformation of the abdominal wall. This anomaly can be corrected by postnatal surgery, either through primary closure of the fascia or delayed closure by means of a silo technique. We present the case of a woman who attended her first prenatal visit in week 26 of pregnancy, with an ultrasonographic finding of fetal gastroschisis.  相似文献   
985.
This article summarizes the main developments reported during the year 2012 concerning ischemic heart disease, together with the most relevant innovations in the management of acute cardiac patients.  相似文献   
986.
Countries thrive on an economic foundation capable of facilitating the fulfillment of human potential in a society that does not renounce major achievements such as the welfare state. A necessary condition is that the “rules of the game”, formal and informal institutions, make what is socially desirable individually attractive. Improving health governance, including its dimension of controlling corruption, and helping Spain out of the current economic crisis are two sides of the same coin. Characterization of health system governance in Spain and analysis of the impact of this governance on health policy, management of healthcare organizations and clinical practice allows an ambitious and feasible agenda to be drawn up of the remaining tasks that health professionals -broadly defined- and social actors should undertake with the support of citizens.  相似文献   
987.
Hypertension is a major contributor to cardiovascular events, such as stroke and myocardial infarction, with accelerated sympathetic nerve activity implicated in its pathogenesis. However, hypertension in many patients is not adequately controlled, despite the availability of numerous medication classes. Novel procedure—as well as device-based strategies, such as percutaneous renal sympathetic nerve denervation therapy—have been developed to improve blood pressure in these refractory patients. Renal sympathetic denervation delivers not only a decrease in blood pressure levels but also renal as well as systemic sympathetic nerve activity. The reduction in blood pressure appears to be sustained over 3 years after the procedure, which implies no counterregulatory mechanism or re-innervation of afferent renal sympathetic nerve so far. Renal sympathetic denervation is expected to be a promising treatment for patients with hypertension, congestive heart failure, chronic kidney disease, and metabolic syndrome implicated in the pathogenesis of potentiated sympathetic nerve activity. This review will focus on the current devices and procedures, their outcomes and prospects in the treatment of hypertension.  相似文献   
988.
Over a century has passed since Ignaz P. Semmelweis demonstrated the association between hand hygiene and nosocomial infections, but this simple procedure is still not recognized by many healthcare workers as one of the most important measures to prevent cross-transmission of microorganisms. A relatively large amount of research has been done, in particular to try to understand why compliance remains so low, in order to implement successful promotion campaigns. This research has generated a fair amount of strong scientific data which are sometimes misunderstood and misused because of myths or certain beliefs. Observational or intervention studies have consistently shown a number of risk factors associated with non-compliance, such as high workload, professional category, or type of ward. Others are thought to be barriers to adequate compliance but have not yet been properly assessed. These include skin irritation due to hand hygiene agents, lack of knowledge of hand hygiene recommendations, or lack of institutional policy. Future interventions to promote hand hygiene will need to address these risk factors, and target the individual healthcare worker, as well as the group or institution if a significant degree of success is to be achieved.  相似文献   
989.
Evaluation of: Luna CM, Bruno DA, García-Morato J et al. Effect of linezolid compared with glycopeptides in methicillin-resistant Staphylococcus aureus severe pneumonia in piglets. Chest 135(6), 1564–1571 (2009).

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a major pathogen in nosocomial infections and accounts for a large proportion of nosocomial pneumonia. However, there are limited antibiotics available for the treatment of this serious and potentially lethal infection. Until recently, the only effective antibiotic was vancomycin, but the oxazolidinones, such as linezolid, have been shown to be a valuable addition to the arsenal of antimicrobial agents that can be used for MRSA pneumonia. Clinical trials have been conducted to compare vancomycin and linezolid head-to-head in pneumonia and, in post hoc subgroup analyses, showed that linezolid use was associated with improved survival. The ensuing debate over these results was dominated by two opinions; there were those who speculated on the mechanism by which linezolid achieved this benefit, namely attributing it to pharmacodynamics and pharmacokinetics, and others who criticized the methodology of the studies and questioned the validity of the results altogether. This study by Luna and colleagues was designed with several goals in mind. The first was to attempt to generate an animal model of MRSA pneumonia in piglets by duplicating techniques used in animal models of Gram-negative pneumonia. Then they studied the effect of three antibiotics (vancomycin, linezolid and teicoplanin) on outcomes in the same model, while simultaneously measuring antibiotic levels in the serum, bronchoalveolar lavage fluid and lung tissue, in an attempt to attribute differences in survival to pharmacological properties of the drugs used. Their results showed a survival benefit only for linezolid, despite the fact that all three antibiotics had levels above MIC in all the compartments sampled, leading them to speculate that linezolid may have improved outcomes by mechanisms not directly related to its antimicrobial actions.  相似文献   
990.
Retroperitoneal hemorrhage is a very rare event, especially during pregnancy, and is associated with high morbimortality for both the mother and fetus. The cause is usually traumatic, but these hemorrhages can occur spontaneously, which further hampers their diagnosis. Presenting symptoms are abdominal pain and maternal hypovolemic shock, with rapid fetal compromise. We present a case of maternal retroperitoneal hemorrhage, which occurred at week 35 of pregnancy due to spontaneous rupture of the left renal vein, although the first manifestation was placental abruption.  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