全文获取类型
收费全文 | 1432篇 |
免费 | 144篇 |
国内免费 | 19篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 56篇 |
妇产科学 | 21篇 |
基础医学 | 335篇 |
口腔科学 | 12篇 |
临床医学 | 125篇 |
内科学 | 362篇 |
皮肤病学 | 21篇 |
神经病学 | 49篇 |
特种医学 | 151篇 |
外国民族医学 | 1篇 |
外科学 | 98篇 |
综合类 | 67篇 |
预防医学 | 96篇 |
眼科学 | 13篇 |
药学 | 71篇 |
中国医学 | 3篇 |
肿瘤学 | 113篇 |
出版年
2021年 | 15篇 |
2019年 | 13篇 |
2018年 | 23篇 |
2015年 | 17篇 |
2014年 | 21篇 |
2013年 | 33篇 |
2012年 | 45篇 |
2011年 | 52篇 |
2010年 | 32篇 |
2009年 | 44篇 |
2008年 | 40篇 |
2007年 | 54篇 |
2006年 | 43篇 |
2005年 | 36篇 |
2004年 | 38篇 |
2003年 | 33篇 |
2002年 | 41篇 |
2001年 | 51篇 |
2000年 | 34篇 |
1999年 | 40篇 |
1998年 | 41篇 |
1997年 | 44篇 |
1996年 | 34篇 |
1995年 | 22篇 |
1994年 | 22篇 |
1993年 | 23篇 |
1992年 | 20篇 |
1991年 | 19篇 |
1990年 | 26篇 |
1989年 | 37篇 |
1988年 | 42篇 |
1987年 | 34篇 |
1986年 | 30篇 |
1985年 | 27篇 |
1984年 | 23篇 |
1983年 | 25篇 |
1982年 | 18篇 |
1981年 | 14篇 |
1980年 | 25篇 |
1979年 | 20篇 |
1978年 | 16篇 |
1977年 | 15篇 |
1976年 | 15篇 |
1975年 | 16篇 |
1974年 | 15篇 |
1972年 | 11篇 |
1927年 | 22篇 |
1926年 | 26篇 |
1925年 | 40篇 |
1924年 | 30篇 |
排序方式: 共有1595条查询结果,搜索用时 15 毫秒
1.
The human visual system is amenable to a number of adaptive processes; one such process, or collection of processes, is the adaptation to blur. Blur adaptation can be observed as an improvement in vision under degraded conditions, and these changes occur relatively rapidly following exposure to blur. The potential important future directions of this research area and the clinical implications of blur adaptation are discussed. 相似文献
2.
Maria C. Chammas Andre C. Oliveira Mario J. D´Ávilla Pedro H. Moraes Marcelo Straus Takahashi 《Ultrasound in medicine & biology》2019,45(1):50-55
We prospectively evaluated the effectiveness of contrast-enhanced ultrasonography (CEUS) for differentiation of benign versus malignant portal vein thrombosis (PVT). We studied a total of 43 patients with chronic liver disease, hepatocellular carcinoma-suggestive nodules and confirmed PVT, in whom the nature of the PVT was confirmed by follow-up imaging (US, computed tomography and/or magnetic resonance imaging) performed up to 6 mo after CEUS. PVT was assessed by US, Doppler US and CEUS with respect to vessel wall disruption and/or invasion, color Doppler vascularization, pulsed Doppler vascularization pattern and CEUS enhancement and vascularization pattern, and thrombi were classified as benign or malignant based on these findings. Follow-up studies revealed malignant PVT in 22 of the 43 patients (51%) and benign PVT in 21 patients (49%). CEUS findings were consistent with follow-up studies in 41 of the 43 patients (95%), with κ?=?0.903 (p < 0.0001), sensitivity?=?91% and specificity?=?100%, indicating that CEUS can be confidently used to differentiate benign from malignant portal vein thrombosis in the setting of chronic liver disease. 相似文献
3.
Noninvasive Intracranial Cerebral Flow Velocity Evaluation in the Emergency Department by Emergency Physicians 总被引:2,自引:0,他引:2
Michael Shafé MD Michael Blaivas MD RDMS Edmond Hooker MD Leigh Straus BS 《Academic emergency medicine》2004,11(7):774-777
Transcranial Doppler (TCD) is an accepted modality for the evaluation of cerebral blood flow velocities. OBJECTIVES: The purpose of this study was to test the feasibility of bedside TCD measurement in the emergency department (ED) with critically ill, intubated patients. METHODS: A prospective convenience sample of patients presenting to a university hospital over a two-month period underwent TCD evaluation of the middle cerebral artery. Intubated patients with head trauma and any patient requiring tracheal intubation were eligible. A 2-MHz Doppler probe was positioned over the temporal bone to acquire blood flow velocities. An emergency medicine resident and research assistant obtained measurements. Continuous TCD tracings were recorded on a video cassette recorder tape for quality assurance review and data collection. Vital signs and therapeutic interventions were also recorded. Flow velocities were measured in cm/s; the peak Resistance Index (RI) was calculated for each patient. RESULTS: A total of 30 patients were enrolled in the study. Adequate tracings were obtained in 25 patients (83%) without a disruption of resuscitation. Tracings could not be obtained in five patients; they were listed as TCD failures. However, in two of these patients, adequate flow velocity tracings were obtained after resuscitation. Four patients were evaluated during tracheal intubation. One patient was monitored successfully during cardiopulmonary resuscitation. The median time required for data acquisition was 1.9 minutes. The mean highest RI for those who expired was 0.84. For those who survived, the mean highest RI was 0.52. The difference of 0.32 was statistically significant (p = 0.04). CONCLUSIONS: Noninvasive blood flow velocity monitoring of the middle cerebral artery using TCD is feasible in the ED when performed at the bedside on intubated patients with traumatic brain injury and others during tracheal intubation and resuscitation. 相似文献
4.
5.
Hausegger KA; Cragg AH; Lammer J; Lafer M; Fluckiger F; Klein GE; Sternthal MH; Pilger E 《Radiology》1994,190(1):199
6.
Serum ionic fluoride levels in haemodialysis and continuous ambulatory peritoneal dialysis patients 总被引:1,自引:1,他引:0
al-Wakeel JS; Mitwalli AH; Huraib S; al-Mohaya S; Abu-Aisha H; Chaudhary AR; al-Majed SA; Memon N 《Nephrology, dialysis, transplantation》1997,12(7):1420-1424
High serum fluoride (F-) in patients with chronic renal failure (CRF) and
end-stage renal disease (ESRD) is associated with risk of renal
osteodystrophy and other bone changes. This study was done to determine F-
in normal healthy controls and patients with ESRD on haemodialysis (HD) or
peritoneal dialysis (PD). Seventeen healthy controls (12 males, 5 females)
and 39 ESRD patients on dialysis (17 males, 22 females) were recruited in
the study in a community with 47.4 +/- 3.28 microM/l (range 44-51 microM/l)
of F- content in drinking water. Control subjects showed a mean serum F-
concentration of 1.08 +/- 0.350 microM/l. Males in control group showed
slightly higher F- levels (1.15 +/- 0.334, range 0.55-1.9 microM/l) than
females (0.92 +/- 0.370, range 0.6-1.5 microM/l). Mean serum F-
concentration did not correlate significantly with age and sex among
control subjects, whereas such correlation was observed in patients with
ESRD on dialysis. Mean serum F- concentration was significantly higher in
patients on dialysis (2.67 +/- 1.09, range 0.8-5.2 microM/l) than normal
controls. When grouped according to sex, the mean serum F- concentration in
males (3.05 +/- 1.04, range 1.8-5.2 microM/l) was significantly higher than
females (2.38 +/- 1.08, range 0.8-5.2 microM/l). When patients were grouped
according to age, it was observed that F- concentration was significantly
higher in patients with age groups 21-70 (2.86 +/- 1.05) than those with
age group 13-20 years (1.42 +/- 0.531). Thus F- concentration correlated
with age and sex, being higher in males and above 20 years. Despite
appreciable clearance of F- (39-90%) across the peritoneum, patients on
CAPD showed higher serum F- concentration than those on HD (3.1 +/- 1.97 vs
2.5 +/- 1.137 microM/l). Of the total 39 patients on dialysis 39% had their
serum F- concentration above 3.0 microM/l, posing the risk of renal
osteodystrophy.
相似文献
7.
Patterns of gene expression and sites of latency in human nerve ganglia are different for varicella-zoster and herpes simplex viruses. 总被引:28,自引:2,他引:26
8.
Focal liver lesions: characterization with triphasic spiral CT 总被引:15,自引:1,他引:14
9.
Frank Baker Ph.D. David Jodrey Ph.D. James Intagliata Ph.D. Harry Straus Ph.D. 《Community mental health journal》1993,29(4):321-331
A cohort of 729 chronically mentally ill patients receiving community support services (CSS) were followed over a nine-month period. Receiving needed community support services was shown to predict change in client functioning as measured by the Global Assessment Scale (GAS) even after the initial values on the GAS, as well as demographic, psychiatric, residential and medication maintenance variables were considered. Adequacy of social support from family, friends and others also contributed to predicting change in global functioning of the CSS patients.Johns Hopkins UniversityPresented at the American Psychological Association Annual Meeting, Washington, D.C., August 16, 1992. 相似文献
10.
Acyclovir suppression of frequently recurring genital herpes. Efficacy and diminishing need during successive years of treatment 总被引:3,自引:0,他引:3
S E Straus K D Croen M H Sawyer A G Freifeld J M Felser J K Dale H A Smith C Hallahan S N Lehrman 《JAMA》1988,260(15):2227-2230
Forty-seven patients with frequently recurring genital herpes participated in one or more of five sequential trials of oral suppressive therapy with 200 mg of acyclovir three times daily from four to 12 months' duration. The prolonged use of acyclovir was extremely well tolerated, and treatment efficacy was sustained through successive studies. Recurrences in eight patients with repeated treatment "failures" were more effectively suppressed with higher doses of acyclovir. All patients experienced recurrent infections after the treatments were completed; however, the mean time to recurrence following each treatment period became progressively longer, and resumption of suppressive therapy was no longer warranted for ten patients. These data indicate the efficacy and safety of chronic suppressive therapy with acyclovir and the value of interrupting prolonged treatment to assess its further need. 相似文献