全文获取类型
收费全文 | 936472篇 |
免费 | 68033篇 |
国内免费 | 1349篇 |
专业分类
耳鼻咽喉 | 13027篇 |
儿科学 | 24464篇 |
妇产科学 | 23401篇 |
基础医学 | 133762篇 |
口腔科学 | 28337篇 |
临床医学 | 81146篇 |
内科学 | 184162篇 |
皮肤病学 | 19311篇 |
神经病学 | 72610篇 |
特种医学 | 37096篇 |
外国民族医学 | 79篇 |
外科学 | 152781篇 |
综合类 | 18139篇 |
现状与发展 | 1篇 |
一般理论 | 237篇 |
预防医学 | 62357篇 |
眼科学 | 21506篇 |
药学 | 72929篇 |
3篇 | |
中国医学 | 2165篇 |
肿瘤学 | 58341篇 |
出版年
2018年 | 9053篇 |
2017年 | 7106篇 |
2016年 | 7825篇 |
2015年 | 8943篇 |
2014年 | 12118篇 |
2013年 | 17688篇 |
2012年 | 24335篇 |
2011年 | 25290篇 |
2010年 | 14962篇 |
2009年 | 14395篇 |
2008年 | 24845篇 |
2007年 | 25952篇 |
2006年 | 26760篇 |
2005年 | 25678篇 |
2004年 | 24835篇 |
2003年 | 23864篇 |
2002年 | 23385篇 |
2001年 | 54911篇 |
2000年 | 56718篇 |
1999年 | 47153篇 |
1998年 | 10803篇 |
1997年 | 9534篇 |
1996年 | 9644篇 |
1995年 | 8973篇 |
1994年 | 8330篇 |
1993年 | 7632篇 |
1992年 | 35598篇 |
1991年 | 34049篇 |
1990年 | 32869篇 |
1989年 | 31985篇 |
1988年 | 29101篇 |
1987年 | 28364篇 |
1986年 | 26385篇 |
1985年 | 25268篇 |
1984年 | 17918篇 |
1983年 | 15213篇 |
1982年 | 7838篇 |
1981年 | 6818篇 |
1979年 | 15846篇 |
1978年 | 10647篇 |
1977年 | 9098篇 |
1976年 | 7914篇 |
1975年 | 8678篇 |
1974年 | 10514篇 |
1973年 | 9910篇 |
1972年 | 9406篇 |
1971年 | 8882篇 |
1970年 | 8456篇 |
1969年 | 7948篇 |
1968年 | 7238篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Hung-Fat Tse Sukumaran Thambar Yok-Lam Kwong Philip Rowlings Greg Bellamy Jane McCrohon Paul Thomas Bruce Bastian John K F Chan Gladys Lo Chi-Lai Ho Wing-Sze Chan Raymond Y Kwong Anthony Parker Thomas H Hauser Jenny Chan Daniel Y T Fong Chu-Pak Lau 《European heart journal》2007,28(24):2998-3005
AIMS: Experimental studies have demonstrated that bone marrow (BM) cells can induce angiogenesis in ischaemic myocardium. Recently, several non-randomized pilot studies have also suggested that direct BM cells implantation appears to be feasible and safe in patients with severe coronary artery diseases (CAD). METHODS AND RESULTS: We performed a randomized, blinded, and placebo-controlled trial in 28 CAD patients. After BM harvesting, we assigned patients to receive low dose (1 x 10(6) cells/0.1 mL, n = 9), high dose (2 x 10(6) cells/0.1 mL, n = 10) autologous BM cells or control (0.1 mL autologous plasma/injection, n = 9) catheter-based direct endomyocardial injection as guided by electromechanical mapping. Our primary endpoint was the increase in exercise treadmill time and our secondary endpoints were changes in Canadian Cardiovascular Society (CCS) and New York Heart Association (NYHA) class, and myocardial perfusion and left ventricular ejection fraction (LVEF) assessed by single-photon emission computed tomography and magnetic resonance imaging, respectively. A total 422 injections (mean 14.6 +/- 0.7 per patient) were successfully performed at 41 targeted ischaemic regions without any acute complication. Baseline exercise treadmill time was 439 +/- 182 s in controls and 393 +/- 136 s in BM-treated patients, and changed after 6 months to 383 +/- 223s and 464 +/- 196 s [BM treatment effect +0.43 log seconds (+53%), 95% CI 0.11-0.74, P = 0.014]. Compared with placebo injection, BM implantation was associated with a significant increase in LVEF (BM treatment effect +5.4%, 95% CI 0.4-10.3, P = 0.044) and a lower NYHA class (odds ratio for treatment effect 0.12, 95% CI 0.02-0.73, P = 0.021) after 6 months, but CCS reduced similarly in both groups. We observed no acute or long-term complications, including ventricular arrhythmia, myocardial damage, or development of intramyocardial tumour or calcification associated with BM implantation. CONCLUSION: Direct endomyocardial implantation of autologous BM cells significantly improved exercise time, LVEF, and NYHA functional class in patients with severe CAD who failed conventional therapy. 相似文献
992.
993.
John P Norvell Andres T Blei Borko D Jovanovic Josh Levitsky 《Liver transplantation》2007,13(10):1428-1434
Hepatitis is a rare complication of herpes simplex virus (HSV), often leading to acute liver failure (ALF), liver transplantation (LT), and/or death. Our aim was to identify variables associated with either survival or progression (death/LT), based on an analysis of cases in the literature and our institution. A total of 137 cases (132 literature, 5 institutional) of HSV hepatitis were identified. The main features at clinical presentation were fever (98%), coagulopathy (84%), and encephalopathy (80%). Rash was seen in less than half of patients. Most cases (58%) were first diagnosed at autopsy and the diagnosis was suspected clinically prior to tissue confirmation in only 23%. Overall, 74% of cases progressed to death or LT, with 51% in acyclovir-treated patients as compared to 88% in the untreated subjects (P=0.03). Variables on presentation associated with death or need for LT compared to spontaneous survival: male gender, age>40 yr, immunocompromised state, ALT>5,000 U/L, platelet count<75x10(3)/L, coagulopathy, encephalopathy, and absence of antiviral therapy. In conclusion, HSV hepatitis has a high mortality and is often clinically unsuspected. Patients who are male, older, immunocompromised, and/or presenting with significant liver dysfunction are more likely to progress to death and should thus be evaluated for LT early. Based on the frequent delay in HSV diagnosis, low risk-benefit ratio, and significantly improved outcomes, empiric acyclovir therapy for patients presenting with ALF of unknown etiology is recommended until HSV hepatitis is excluded. 相似文献
994.
J.D. Schold T.R. Srinivas G. Guerra A.I. Reed R.J. Johnson I.D. Weiner R. Oberbauer J.S. Harman A.W. Hemming H.U. Meier-Kriesche 《American journal of transplantation》2007,7(3):550-559
Research suggests that end-stage renal disease patients with elevated body mass index (BMI) have superior outcomes on dialysis. In contrast, low and high BMI patients represent the highest risk cohorts for kidney transplant recipients. The important question remains concerning how to manage transplant candidates given the potentially incommensurate impact of BMI by treatment modality. We conducted a retrospective analysis of waitlisted and transplanted patients in the United States from 1990 to 2003. We constructed Cox models to evaluate the effect of BMI on mortality of waitlisted candidates and identified risk factors for rapid weight change. We then assessed the impact of weight change during waitlisting on transplant outcomes. Decline in BMI on the waiting list was not protective for posttransplant mortality or graft loss across BMI strata. Substantial weight loss pretransplantation was associated with rapid gain posttransplantation. The highest risk for death was among listed patients with low BMI (13-20 kg/m(2), adjusted hazard ratio = 1.47, p < 0.01). Approximately one-third of candidates had a change in BMI category prior to transplantation. While observed declines in BMI may be volitional or markers of disease processes, there is no evidence that candidates have improved transplant outcomes attributable to weight loss. Prospective trials are needed to evaluate the efficacy of weight loss protocols for candidates of kidney transplantation. 相似文献
995.
T Alp Ikizler 《Journal of renal nutrition》2007,17(1):13-16
Insulin deficiency is known to be associated with a state of increased muscle protein breakdown; this process is mediated by the ubiquitin-proteasome pathway. Convincing in vitro data are further supported by extensive studies in humans with insulin deprivation and are further substantiated by reversal of muscle protein breakdown with insulin treatment. In patients with end-stage renal disease (ESRD) and diabetes mellitus (DM), muscle protein breakdown is enhanced in both acute and chronic conditions. Recent data also point to the potential protein catabolic effects of insulin resistance combined with insulin deficiency. Because ESRD is associated with a state of insulin resistance, uremic muscle wasting may also be mediated by this pathway. 相似文献
996.
997.
G. S. Sayuk T. L. Leet M. A. Schnitzler P. H. Hayashi 《American journal of transplantation》2007,7(1):151-160
Deceased donor factors associated with poor graft outcome are well known, but how often these factors lead to livers left untransplanted is poorly defined. A nested, case-control study was conducted using the United Network for Organ Sharing (UNOS) database from 1987 to 2005. Only those donating >/=1 solid organ were included. Primary outcome was livers not transplanted (LNT, cases) versus transplanted (LT, controls). Primary variables for multivariate analysis were donor age and obesity. Covariates included donation after cardiac death (DCD), cerebral vascular accident death, viral serologies, cancer, ALT and bilirubin. There were 23 373 (26%) LNT's from 91 362 donors who donated at least one organ. Percent LNT fell over time (1987-1990: 48%; 1991-1995: 29%; 1996-2000: 21%; 2000-2005: 16%; p < 0.01). Increased age (odds ratio: 4.2, 95% confidence interval 3.6-4.9, p < 0.01) and obesity (2.1, 1.9-2.3, p < 0.01) were significantly associated with LNT across all time periods. Other significant factors included DCD and elevated ALT. For 2001-2005, population attributable risk indicate that age >40, abnormal ALT and obesity account for 32.6%, 25.3% and 9.2% of untransplanted livers, respectively. Use of expanded criteria livers has pushed LNT lower in spite of an aging and heavier donor population. Nevertheless, age and obesity still account for a significant portion of untransplanted livers. 相似文献
998.
E S C Korf E C W van Straaten F-E de Leeuw W M van der Flier F Barkhof L Pantoni A M Basile D Inzitari T Erkinjuntti L-O Wahlund E Rostrup R Schmidt F Fazekas P Scheltens 《Diabetic medicine》2007,24(2):166-171
HYPOTHESIS: Based on recent findings on the association between vascular risk factors and hippocampal atrophy, we hypothesized that hypertension and diabetes mellitus (DM) are associated with medial temporal lobe atrophy (MTA) in subjects without disability, independent of the severity of white matter hyperintensities. METHODS: In the Leukoaraiosis And DISability in the elderly (LADIS) study, we investigated the relationships between DM, hypertension, blood pressure and MTA in 582 subjects, stratified by white matter hyperintensity severity, using multinomial logistic regression. MTA was visually scored for the left and right medial temporal lobe (score 0-4), and meaned. RESULTS: Mean age was 73.5 years (sd 5.1), 54% was female. Of the subjects, 15% had DM, and 70% had a history of hypertension. The likelihood of having MTA score 3 was significantly higher in subjects with DM (OR 2.9; 95% CI: 1.1-7.8) compared with an MTA score of 0 (no atrophy). The odds ratio for MTA score 2 was not significantly increased (OR 1.8; CI: 0.9-4). Systolic and diastolic blood pressure and a history of hypertension were not associated with MTA. There was no interaction between DM and hypertension. Stratification on white matter hyperintensities (WMH) did not alter the associations. CONCLUSION: Our study strengthens the observation that MTA is associated with DM, independently of the amount of small vessel disease as reflected by WMH. 相似文献
999.
S Cupisti R Dittrich H Binder N Kajaia I Hoffmann T Maltaris M W Beckmann A Mueller 《Experimental and clinical endocrinology & diabetes》2007,115(6):380-386
There is growing evidence that obesity in women lead to a more severe form of hyperandrogenism and other endocrine abnormalities which may have some health implications later in life. Obese females are at higher risk for metabolic syndrome due to severe hyperandrogenemia. Calculated values for free testosterone are equivalent to those obtained by equilibrium dialysis, which is one of the reference measurement procedures (RMP) for estimation of free testosterone and may be capable of replacing values estimated using RMP's. For adult women correlations of body mass index (BMI) with calculated free (cFT) and bioavailable testosterone (cBT) are still rare, while these data are reported for peripubertal and adolescent girls. In this study we aimed to investigate the association between BMI and different androgen parameters (including calculated free and bioavailable testosterone, free androgen index, and sex hormone-binding globulin [SHBG]) in adult women with Hirsutism and with PCOS. In hirsute women with BMI > or = 25 kg/m2 measured total testosterone (TT) was significantly higher, SHBG was significantly lower and the calculated androgen parameter (FAI, cFT and cBT) were significantly higher compared to women with BMI < 25 kg/m2. In PCOS women with BMI > or = 25 kg/m2 TT was significantly higher, SHBG was significantly lower and the calculated androgen parameter (FAI, cFT and cBT) were also significantly higher compared to women with BMI < 25 kg/m2. In both the Hirsutism and PCOS-group there was a positive correlation between BMI and TT, cFT, and cBT, while BMI was negatively correlated with SHBG. In summary, in adult women with Hirsutism and PCOS obesity is associated with increased levels of TT and decreased levels of SHBG resulting in significant elevated calculated free and bioavailable testosterone levels. Obesity might lead to a more severe form of hyperandrogenism with elevated calculated free and bioavailable testosterone in the study population. 相似文献
1000.
Y Imamura K Yanagihara Y Fukuda Y Kaneko M Seki K Izumikawa Y Miyazaki Y Hirakata T Sawa J P Wiener-Kronish S Kohno 《The European respiratory journal》2007,29(5):965-968
Pseudomonas aeruginosa is one of the most important pathogens in patients with chronic airway conditions, such as cystic fibrosis and diffuse panbronchiolitis. Type III secretion system-mediated virulence factors contribute to the lung damage in chronic P. aeruginosa infection. The effects of the anti-PcrV immunoglobulin (Ig)G, which blocks the type III secretion system, were evaluated in a mouse model of chronic P. aeruginosa infection. On bacteriological examination, anti-PcrV IgG showed no bactericidal effects. On bronchoalveolar lavage fluid (BALF) analysis, total cell number and neutrophil ratios in the anti-PcrV IgG-treated groups were lower than those in the control group. In addition, macrophage inflammatory protein-2, tumour necrosis factor-alpha, and interleukin-beta concentrations in BALF were lower in the anti-PcrV IgG-treated groups when compared with controls. Plasma anti-PcrV IgG titre was elevated after administration of anti-PcrV IgG. Although plasma titre decreased gradually, a significant concentration was maintained during the experimental period. These data suggest that anti-PcrV immunoglobulin G reduces the inflammatory reaction caused by chronic Pseudomonas aeruginosa respiratory infection and may be useful in treating respiratory diseases. 相似文献