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   9039篇
  免费   916篇
  国内免费   27篇
耳鼻咽喉   60篇
儿科学   300篇
妇产科学   186篇
基础医学   1172篇
口腔科学   139篇
临床医学   990篇
内科学   1957篇
皮肤病学   65篇
神经病学   751篇
特种医学   374篇
外国民族医学   5篇
外科学   1225篇
综合类   269篇
现状与发展   1篇
一般理论   15篇
预防医学   1054篇
眼科学   224篇
药学   822篇
中国医学   2篇
肿瘤学   371篇
  2022年   58篇
  2021年   135篇
  2020年   87篇
  2019年   156篇
  2018年   163篇
  2017年   131篇
  2016年   147篇
  2015年   160篇
  2014年   224篇
  2013年   308篇
  2012年   453篇
  2011年   482篇
  2010年   239篇
  2009年   224篇
  2008年   451篇
  2007年   496篇
  2006年   441篇
  2005年   465篇
  2004年   446篇
  2003年   376篇
  2002年   378篇
  2001年   277篇
  2000年   279篇
  1999年   216篇
  1998年   107篇
  1997年   124篇
  1996年   104篇
  1995年   68篇
  1994年   87篇
  1993年   87篇
  1992年   174篇
  1991年   166篇
  1990年   153篇
  1989年   142篇
  1988年   124篇
  1987年   140篇
  1986年   105篇
  1985年   117篇
  1984年   92篇
  1983年   91篇
  1982年   78篇
  1981年   62篇
  1980年   69篇
  1979年   118篇
  1978年   71篇
  1977年   68篇
  1974年   64篇
  1973年   62篇
  1972年   57篇
  1968年   64篇
排序方式: 共有9982条查询结果,搜索用时 15 毫秒
101.
Diabetes mellitus associated with cystic fibrosis   总被引:4,自引:0,他引:4  
The prevalence of overt diabetes mellitus and carbohydrate intolerance was studied in 448 patients with cystic fibrosis (CF). Insulin-dependent diabetes (IDDM) developed in 7.6% of patients (13 male and 21 female). Survival was significantly lower (P less than 0.01) in the IDDM-CF group, with fewer than 25% surviving to age 30 years, whereas nearly 60% of the nondiabetic CF population reached this age. A significant deterioration in CF clinical status, based on NIH score, became apparent 2 years before onset of overt IDDM (P less than 0.05 at 2 years prior, P less than 0.01 at IDDM diagnosis). Total glycosylated hemoglobin (HbA1) was significantly (P less than 0.001) higher for the total CF population (7.3% +/- 1.2%) than for the general non-CF population (6.5% +/- 0.7%), and in the IDDM-CF group (P less than 0.05) compared with normoglycemic CF control patients. Female patients had a higher mean HbA1 after 12 years of age than their male counterparts did (P less than 0.02). HBA1 did not predict the development of IDDM, but there was a weak inverse relationship between HbA1 and both NIH clinical score (r = -0.41, P less than 0.02) and standard pulmonary function tests (forced vital capacity, r = -0.25, P less than 0.01) in the general CF population. Therefore, impaired carbohydrate tolerance in CF is associated with progressive clinical deterioration.  相似文献   
102.
Elliott JP 《Clinics in perinatology》2007,34(4):599-609, vii
Preterm labor (PTL) in a multiple gestation occurs frequently and is a common reason for preterm delivery (PTD). Management strategies for multiple gestations must be directed at early detection of PTL and effective strategies to delay or prevent PTD. Unlike singleton gestation where identification of patients at risk for PTL is often difficult, every multiple gestation is at risk for PTL, so all patients can be managed as being at risk. Although PTL is a significant cause of PTD, one must recognize that there are other reasons for delivery in multiple gestations. Clinicians must treat the whole patient and extend the pregnancy to the most advanced gestational age possible that is consistent with the best outcome.  相似文献   
103.
104.
1. Streptococcal proteinase is derived from an inactive precursor found in culture filtrates of proteinase-producing streptococci. 2. The precursor can be converted into the proteinase by low concentrations of trypsin but not by chymotrypsin. 3. In cultures grown in suitable media the conversion of precursor to proteinase is effected autocatalytically. This reaction occurs under reducing conditions and is initiated by active proteinase present in low concentrations with the precursor. 4. The autocatalytic reaction is suppressed or retarded by conditions which decrease the activity of the proteinase, e.g. by growing cultures at 22°C. instead of at 37°C. or by growing them under markedly aerobic conditions. It is also retarded in the presence of casein.  相似文献   
105.
Background:Pneumonia is a frequent diagnosis for patients admitted to Australian intensive care units (ICUs) for invasive ventilation. Physiotherapists in ICU provide interventions to enhance respiratory function and physical recovery.Objective:This retrospective cohort study aimed to describe physiotherapy management of adults with pneumonia who require invasive mechanical ventilation in a single Level 3 ICU in a quaternary teaching hospital.Methods:All adults admitted with a medical diagnosis of pneumonia requiring invasive mechanical ventilation over a two-year period were included. Demographic and clinical data, including APACHE II score, ventilator-free days (VFDs) to day 28, ICU length of stay (LOS), and type and frequency of physiotherapy episodes of care delivered in ICU, were collected from electronic medical records. Correlations between VFDs to day 28 and the frequency of physiotherapy interventions delivered per subject were examined using Spearman’s rho analysis.Results:From 208 records screened, 66 subjects with an ICU admission diagnosis of pneumonia, who required invasive mechanical ventilation, were included. Median (IQR) ICU LOS was 10 (5–17) days, and mortality rate was 15.2% (n=10). The cohort had a median of 20.5 (IQR 2–25) VFDs to day 28. Community-acquired pneumonia (66.7%, n=44) was the most frequent type of pneumonia diagnosis. There were 1110 episodes of physiotherapy care, with patients receiving a median of 13.5 (IQR 6.8–21.3) episodes during their ICU stay, with a median rate of 1.2 (IQR 1.0–1.6) episodes per day. Over 96.7% of patients with pneumonia received physiotherapy treatment during their ICU stay. Overall, physiotherapy treatments consisting only of respiratory techniques were most commonly provided (55.1%, n=612). Airway suctioning (92.4%, n=61), patient positioning (72.7%, n=48) or positioning advice to nurses (77.3%, n=51), and hyperinflation techniques (63.6%, n=42) were among the respiratory techniques most delivered.Conclusion:This study described the current intensive care physiotherapy management in a single center for adults with pneumonia who required invasive mechanical ventilation, demonstrating that respiratory physiotherapy interventions are often provided for this ICU patient cohort. Further research is warranted to determine the efficacy of respiratory physiotherapy interventions to justify their use for ICU patients with pneumonia receiving invasive mechanical ventilation.  相似文献   
106.
Gel chromatography with Dyematrex blue B gel and ion exchange chromatography with a methylcellulose cation exchange column have been used to isolate a toxin present in partially purified saline extracts of the dahlia sea anemone Tealia felina. Toxin activity was assessed by its histaminolytic activity. A ten-fold increase in activity per mg protein was achieved in these two steps. Final purification on a Sephacryl column yielded an apparently pure protein with a molecular weight of 7800. The amino acid composition of this compound was determined.  相似文献   
107.
OBJECT: Nitric oxide (NO) metabolism may influence vasospasm after subarachnoid hemorrhage (SAH). It has been demonstrated in recent studies that erythrocytes carry NO for release in vessels, whereas transfused erythrocytes may lack stored NO. Several converging lines of evidence also indicate that blood transfusion may exacerbate poor outcomes in some critically ill patients. In this study the authors hypothesized that patients with SAH who received red blood cell (RBC) transfusions were at greater risk for vasospasm and poor outcome. METHODS: The authors retrospectively reviewed a prospective observational database, including hospital records, computerized tomography (CT) scans, and pre- and postoperative four-vessel angiograms, in which the management methods used in 441 patients undergoing surgery for ruptured cerebral aneurysms were described. Two hundred seventy patients (61.2%) received an RBC transfusion during their hospital stay. After adjustment for Hunt and Hess grade, SAH grade on CT scans, delay between rupture and surgery, smoking status, and intraoperative aneurysm rupture, a worse outcome was more likely in patients who received intraoperative blood (odds ratio [OR] 2.44, confidence interval [CI] 1.32-4.52; 120 patients). Intraoperative RBC transfusion did not influence subsequent angiographically confirmed vasospasm (OR 0.92, CI 0.6-1.4). Worse outcome was observed in patients who received blood postoperatively (OR 1.81, CI 1.21-2.7), but not after adjustments were made for confounding variables (OR 1.48, CI 0.83-2.63). Angiographic vasospasm was observed in 217 patients and, after adjusting for confounding variables, was more frequent among patients who received postoperative RBC transfusion (OR 1.68, CI 1.02-2.75). Among patients in whom angiographically confirmed vasospasm developed there was a tendency to have received more blood than in those with no vasospasm; however, a clear dose-dependent response was not observed. CONCLUSIONS: Development of angiographically confirmed vasospasm after SAH is associated with postoperative RBC transfusion and worse outcome is associated with intraoperative RBC transfusion. Before blood is transfused, patients with SAH should be carefully assessed to determine if they are symptomatic because of anemia.  相似文献   
108.
109.
110.
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