全文获取类型
收费全文 | 544篇 |
免费 | 40篇 |
专业分类
儿科学 | 31篇 |
妇产科学 | 10篇 |
基础医学 | 59篇 |
口腔科学 | 14篇 |
临床医学 | 70篇 |
内科学 | 113篇 |
皮肤病学 | 14篇 |
神经病学 | 13篇 |
特种医学 | 135篇 |
外科学 | 27篇 |
综合类 | 17篇 |
预防医学 | 19篇 |
眼科学 | 1篇 |
药学 | 35篇 |
肿瘤学 | 26篇 |
出版年
2022年 | 5篇 |
2021年 | 8篇 |
2019年 | 4篇 |
2018年 | 10篇 |
2016年 | 6篇 |
2015年 | 13篇 |
2014年 | 8篇 |
2013年 | 28篇 |
2012年 | 4篇 |
2011年 | 5篇 |
2010年 | 24篇 |
2009年 | 27篇 |
2007年 | 5篇 |
2006年 | 6篇 |
2005年 | 5篇 |
2004年 | 6篇 |
2001年 | 5篇 |
1999年 | 8篇 |
1998年 | 29篇 |
1997年 | 30篇 |
1996年 | 35篇 |
1995年 | 26篇 |
1994年 | 27篇 |
1993年 | 21篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 17篇 |
1988年 | 13篇 |
1987年 | 13篇 |
1986年 | 10篇 |
1985年 | 9篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 10篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 7篇 |
1977年 | 13篇 |
1976年 | 8篇 |
1975年 | 10篇 |
1958年 | 5篇 |
1957年 | 6篇 |
1956年 | 7篇 |
1955年 | 14篇 |
1954年 | 12篇 |
1949年 | 7篇 |
1948年 | 7篇 |
1947年 | 3篇 |
1946年 | 3篇 |
排序方式: 共有584条查询结果,搜索用时 31 毫秒
61.
62.
63.
JJ Korelitz ; AE Williams ; MP Busch ; TF Zuck ; HE Ownby ; LJ Matijas ; DJ Wright 《Transfusion》1994,34(10):870-876
BACKGROUND: Most blood centers utilize a confidential unit exclusion (CUE) process, intended to reduce the risk of transfusion-associated infectious diseases by allowing high-risk donors confidentially to exclude their blood from use for transfusion. The effectiveness of this method remains controversial. STUDY DESIGN AND METHODS: Confirmatory or supplemental test results for antibodies to human immunodeficiency virus, human T-lymphotropic virus type I, and hepatitis C virus, as well as hepatitis B surface antigen and syphilis and screening test results for antibodies to hepatitis B core (antigen) and alanine aminotransferase levels were obtained for approximately 1.8 million units donated during 1991 and 1992 at five blood centers within the United States. The prevalences of these infectious disease markers in units that the donors confidentially excluded (CUE+) and units that the donors did not exclude (CUE-) were calculated and examined within demographic subgroups. RESULTS: Units that were CUE+ were 8 to 41 times more likely to be seropositive for antibodies to human immunodeficiency virus and hepatitis C virus, hepatitis B surface antigen, and syphilis and three to four times more likely to react for antibody to hepatitis B core (antigen) or to have elevated alanine aminotransferase levels than units that were CUE- (p < 0.001). The positive predictive value of CUE (the percentage of CUE+ units that were confirmed seropositive for any marker) was 3.5 percent, and the sensitivity of CUE (the percentage of confirmed-seropositive units that were CUE+) was 2.3 percent. CONCLUSION: The current CUE process has low sensitivity and apparently low positive predictive value, and in many cases, it appeared that donors misunderstood it. Yet, CUE was not a “random process,” as CUE+ units were more likely to be seropositive for any infectious disease marker than CUE- units. This suggests that efforts to improve the CUE system may be warranted. As risk factors for transfusion-transmitted infection become more difficult to identify by history-based screening, however, such efforts may have limited effect. 相似文献
64.
Total radical trapping antioxidant potential (TRAP) and exercise 总被引:1,自引:0,他引:1
Sharpe PC; Duly EB; MacAuley D; McCrum EE; Mulholland C; Stott G; Boreham CA; Kennedy G; Evans AE; Trinick TR 《QJM : monthly journal of the Association of Physicians》1996,89(3):223-228
The relationship between physical activity, physical fitness and total
radical trapping antioxidant potential (TRAP) was examined in the Northern
Ireland Health and Activity Survey. This was a cross-sectional population
study (n = 1600) using a two-stage probability sample of the population.
TRAP was calculated using the sum of the individual serum antioxidant
concentrations (urate, protein thiols, ascorbate, alpha tocopherol and
bilirubin) multiplied by their respective stoichiometric values. Physical
fitness was determined by estimation of VO2max by extrapolation from
submaximal oxygen uptake, and physical activity was recorded by
computer-assisted interview. Mean serum TRAP concentrations were
significantly higher in males (653 +/- 8.2 mumol/l, mean +/- SEM) compared
to females (564 +/- 8.0 mumol/l) (p < 0.0001). Both male and female
smokers had significantly lower TRAP values than non-smokers (males p <
0.0001, females p = 0.02). In females, there was a positive relationship of
TRAP with age (p < 0.001) and body mass index (p < 0.001) but a
negative relationship with physical fitness (p < 0.05). The known
beneficial effects of exercise and activity do not appear to be directly
mediated through increased antioxidant status.
相似文献
65.
66.
67.
MATTHIAS W. KÖNIG MD † ANNA M. VARUGHESE MD MPH † KATHLEEN A. BRENNEN CRNA SEAN BARCLAY CRNA T. MICHAEL SHACKLEFORD DO † PAUL J. SAMUELS MD † KRISTIN GORMAN BS JILLIAN ELLIS BA YU WANG MS ‡ TODD G. NICK PHD †‡ 《Paediatric anaesthesia》2009,19(8):748-755
Background: Pediatric dental procedures are increasingly performed under general anesthesia because of the inability to cooperate, situational anxiety, or other behavioral problems. Volatile anesthetics have been associated with emergence delirium in children, whereas the use of propofol for anesthetic maintenance has been shown to reduce the incidence of emergence delirium after other types of surgeries. The aim of this study is to compare a sevoflurane-based anesthetic with a propofol-based technique as it relates to the incidence of emergence delirium and the quality of recovery after pediatric dental surgery, in patients who present with risk factors for perioperative behavioral issues.
Methods: We prospectively collected data of 179 pediatric patients scheduled for ambulatory dental surgery using a double-blind and randomized trial design. Subjects were anesthetized following standardized protocols for either a sevoflurane- or a propofol-based technique. The incidence of emergency delirium, as measured by the Pediatric Anesthesia Emergence Delirium score, was the primary outcome. Secondary outcomes included the incidence of postoperative nausea and vomiting (PONV), number of nursing interventions in the recovery room, time to discharge readiness, and parental satisfaction.
Results: We found no difference in the incidence of emergence delirium after both types of anesthesia. However, use of sevoflurane significantly increased both the risk of PONV and the number of postoperative nursing interventions. Discharge criteria were met about 10 min earlier in patients anesthetized with sevoflurane. Parental satisfaction was equally high with both anesthesia regimens.
Conclusions: A propofol-based anesthetic technique did not lead to a lower incidence of emergence delirium after dental surgery in children but did result in significantly less PONV and fewer postoperative nursing interventions. 相似文献
Methods: We prospectively collected data of 179 pediatric patients scheduled for ambulatory dental surgery using a double-blind and randomized trial design. Subjects were anesthetized following standardized protocols for either a sevoflurane- or a propofol-based technique. The incidence of emergency delirium, as measured by the Pediatric Anesthesia Emergence Delirium score, was the primary outcome. Secondary outcomes included the incidence of postoperative nausea and vomiting (PONV), number of nursing interventions in the recovery room, time to discharge readiness, and parental satisfaction.
Results: We found no difference in the incidence of emergence delirium after both types of anesthesia. However, use of sevoflurane significantly increased both the risk of PONV and the number of postoperative nursing interventions. Discharge criteria were met about 10 min earlier in patients anesthetized with sevoflurane. Parental satisfaction was equally high with both anesthesia regimens.
Conclusions: A propofol-based anesthetic technique did not lead to a lower incidence of emergence delirium after dental surgery in children but did result in significantly less PONV and fewer postoperative nursing interventions. 相似文献
68.
A Choppin I Irwin L Lach MG McDonald AE Rettie L Shao C Becker MP Palme X Paliard S Bowersox DM Dennis P Druzgala 《British journal of pharmacology》2009,158(6):1536-1547
Background and purpose:
Tecarfarin (ATI-5923) is a novel vitamin K epoxide reductase inhibitor that is metabolized by esterase (mainly human carboxylesterase 2) to a single major metabolite, ATI-5900, in rats, dogs and humans. Tecarfarin is not significantly metabolized by CYP450 enzymes. The objective of this study was to test and compare the efficacy of tecarfarin with that of warfarin, when administered either intravenously or once a day orally, to produce stable anticoagulation in beagle dogs.Experimental approach:
Effects on coagulation were assessed by measuring the activity levels of Factor VII and Factor X and thromboplastin-induced coagulation times, reported as prothrombin time (PT).Key results:
Continuous intravenous infusions and oral administration of tecarfarin and warfarin caused a dose-dependent decrease in activity of Factor VII and Factor X, and associated increase in PT. Intravenous fresh frozen canine plasma or subcutaneous vitamin K1 treatment reversed the anticoagulant effects of orally administered tecarfarin. Consistent with the inhibitory effects of amiodarone on CYP2C9, co-administration of amiodarone significantly increased the anticoagulation effect of warfarin and plasma warfarin concentrations. In contrast, amiodarone had no effect on the anticoagulation induced by tecarfarin or tecarfarin plasma concentrations in this model.Conclusions and implications:
Overall, the data presented herein indicate that tecarfarin, via a vitamin K-dependent mechanism, causes changes in key parameters of haemostasis in beagle dogs that are consistent with effective anticoagulation. Compared to warfarin it has a decreased potential to interact metabolically with drugs that inhibit CYP450 enzymes and, therefore, may offer an improved safety profile for patients. 相似文献69.
Christine AE Schutgens Merel Schuring Toon AJ Voorham Alex Burdorf 《BMC public health》2009,9(1):197-11
Background
The relationship between poor health and unemployment is well established. Health promotion among unemployed persons may improve their health. The aims of this study were to investigate characteristics of non-participants and drop-outs in a multidisciplinary health promotion programme for long-term unemployed persons with health complaints, to evaluate changes in physical health among participants, and to investigate determinants of improvement in physical health. 相似文献70.