全文获取类型
收费全文 | 1087篇 |
免费 | 48篇 |
国内免费 | 147篇 |
专业分类
儿科学 | 68篇 |
妇产科学 | 5篇 |
基础医学 | 68篇 |
口腔科学 | 21篇 |
临床医学 | 164篇 |
内科学 | 284篇 |
皮肤病学 | 29篇 |
神经病学 | 18篇 |
特种医学 | 310篇 |
外科学 | 57篇 |
综合类 | 26篇 |
预防医学 | 55篇 |
眼科学 | 13篇 |
药学 | 112篇 |
1篇 | |
肿瘤学 | 51篇 |
出版年
2023年 | 5篇 |
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 9篇 |
2018年 | 18篇 |
2017年 | 9篇 |
2016年 | 10篇 |
2015年 | 16篇 |
2014年 | 16篇 |
2013年 | 39篇 |
2012年 | 15篇 |
2011年 | 17篇 |
2010年 | 32篇 |
2009年 | 42篇 |
2008年 | 23篇 |
2007年 | 110篇 |
2006年 | 23篇 |
2005年 | 37篇 |
2004年 | 16篇 |
2003年 | 3篇 |
2002年 | 21篇 |
2001年 | 27篇 |
2000年 | 14篇 |
1999年 | 21篇 |
1998年 | 80篇 |
1997年 | 79篇 |
1996年 | 71篇 |
1995年 | 65篇 |
1994年 | 43篇 |
1993年 | 53篇 |
1992年 | 8篇 |
1991年 | 20篇 |
1990年 | 13篇 |
1989年 | 51篇 |
1988年 | 32篇 |
1987年 | 32篇 |
1986年 | 25篇 |
1985年 | 25篇 |
1984年 | 19篇 |
1983年 | 12篇 |
1982年 | 27篇 |
1981年 | 14篇 |
1980年 | 14篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 16篇 |
1976年 | 28篇 |
1975年 | 13篇 |
排序方式: 共有1282条查询结果,搜索用时 0 毫秒
991.
Aims: To determine the prevalence of diabetes mellitus and its possible causes and to assess its control in a high secure hospital. Methods: A cross sectional survey and a prospective cohort study were conducted. The cross sectional survey included 408 patients admitted under the Mental Health Act, and the prospective study included 22 patients with known diabetes followed up for 24 months. The outcome measures evaluated were drug treatment, status of microvascular and macrovascular complications, glycated haemoglobin, and body mass index. Results: In the cross sectional survey, 35 out of 408 patients (8.6%; 95% confidence interval 5.9% to 11.3%) had known diabetes, and all of these had type 2 diabetes. Obesity, cigarette smoking, schizophrenia, and antipsychotic drug use were frequent, and weight gain was common after hospital admission. Glycaemic control was variable, and, although a majority of patients were above recommended treatment targets, control remained stable over the follow up period. Conclusions: Type 2 diabetes was common in this hospital. Both its prevalence and the suboptimal glycaemic control in some patients probably relate to sedentary life, dietary factors, smoking, and perhaps widespread use of antipsychotic drugs. However, regular multidisciplinary input enabled most patients to maintain relatively stable glycaemic control, with good control of blood pressure and lipids, at levels similar to those seen in community and hospital diabetic clinics. Further modification of lifestyle risk factors is probably needed to reduce the prevalence and impact of diabetes in this patient group. 相似文献
992.
Pinkney AE Harshbarger JC May EB Melancon MJ 《Archives of environmental contamination and toxicology》2004,46(4):492-501
Brown bullheads (Ameiurus nebulosus) were collected from 2 locations near Baltimore, Maryland, Back River and Furnace Creek, and 1 (reference) location, Tuckahoe River, to compare the prevalence of tumors (liver and skin) and visible skin lesions (fin erosion and abnormal barbels). Cytochrome P450 activity measured as ethoxyresorufin-O-deethylase, biliary PAH-like fluorescent metabolites, and fillet contaminant concentrations were determined as indicators of exposure in a randomly selected subset of the fish. There were no significant differences in liver tumor prevalence: Back River = 8% (4/50), Furnace Creek = 0% (0/50), and Tuckahoe River = 2.6% (1/39; p = 0.20, extension of Fishers exact test). Skin tumor prevalence was as follows: Furnace Creek = 12% (6/50), Back River = 8% (4/50), and Tuckahoe River = 0% (0/39; p = 0.063). In the Back River fish, there was a 40% (20/50) prevalence of fin erosion and a 28% (14/50) prevalence of abnormal (shortened, clubbed, or missing) barbels. Fin erosion was not observed in the other collections, and only 10% (5/50) of the Furnace Creek fish had abnormal barbels (p < 0.001 for both lesions). There were statistically significant differences in mean EROD activity, with levels in Furnace Creek and Back River fish approximately twice that found in Tuckahoe River fish. There were also significant differences in mean benzo(a)pyrene-like bile metabolite concentrations: the lowest mean was in the Tuckahoe River fish, 8 times higher in Furnace Creek fish, and 13 times higher in Back River fish. Of the 3 groups, the Back River bullheads appear to be most adversely affected by contaminant exposure because they had the highest prevalence of liver tumors, fin erosion, and abnormal barbels. 相似文献
993.
Appendicitis in children: low-dose CT with a phantom-based simulation technique--initial observations 总被引:2,自引:0,他引:2
Fefferman NR Bomsztyk E Yim AM Rivera R Amodio JB Pinkney LP Strubel NA Noz ME Rusinek H 《Radiology》2005,237(2):641-646
PURPOSE: To retrospectively determine the accuracy of low-dose (20-mAs) computed tomography (CT) in the diagnosis of acute appendicitis in children by using a technique that enables the simulation of human CT scans acquired at a lower tube current given the image acquired at a standard dose. MATERIALS AND METHODS: Institutional review board approval was obtained, informed consent was not required, and the study was HIPAA compliant. The authors reviewed 100 standard-dose pediatric abdominal-pelvic CT scans (50 positive and 50 negative scans) obtained in 100 patients and corresponding simulated low-dose (20-mAs) scans. The standard-dose scans were obtained for evaluation in patients suspected of having appendicitis. Scans were reviewed in randomized order by four experienced pediatric radiologists. The patients with positive findings included 21 girls (mean age, 9.2 years) and 29 boys (mean age, 8.4 years). The patients with negative findings included 28 girls (mean age, 9.2 years) and 22 boys (mean age, 8.4 years). Simulation was achieved by adding noise patterns from repeated 20-mAs scans of a pediatric pelvis phantom to the original scans obtained with a standard tube current. Observers recorded their confidence in the diagnosis of appendicitis by using a six-point scale. Dose-related changes were analyzed with generalized estimating equations and the nonparametric sign test. RESULTS: There was a statistically significant (P < .001, sign test) decrease in both sensitivity and accuracy with a lower tube current, from 91.5% with the original tube current to 77% with the lower tube current. A low dose was the only statistically significant (P < .001) risk factor for a false-negative result. The specificity was unchanged at 94% for both the images obtained with the original tube current and the simulated low-dose images. The overall accuracy decreased from 92% with the original dose to 86% with the low dose. CONCLUSION: Preliminary findings indicate that it is feasible to optimize the CT dose used to evaluate appendicitis in children by using phantom-based computer simulations. 相似文献
994.
995.
Petrella JR Shah LM Harris KM Friedman AH George TM Sampson JH Pekala JS Voyvodic JT 《中国神经肿瘤杂志》2006,4(2):133-133
Purpose: To prospectively evaluate the effect of preoperative functional magnetic resonance (MR) imaging localization of language and motor areas on therapeutic decision making in patients with potentially resectable brain tumors. Materials and Methods: The Institutional Review Board approved this HIPAA-compliant study, and each patient gave written informed consent. Thirty-nine consecutive patients (19 male, 20 female; mean age, 42.2 years) referred for functional MR imaging for possible tumor resection were prospectively evaluated. A preoperative diagnosis of brain tumor was made in all patients. 相似文献
996.
Selective suprapubic urine aspiration was performed in 905 of 12 942 consecutive live-born infants and showed the presence of infection in 64 (0-5%). A majority (84%) of the infected infants were males. Radiological abnormalities were detected in 35 (55%). Because of this high incidence of abnormalities, which when diagnosed might alter management, it is suggested that radiological investigations be performed in newborn infants with proven urinary infection. 相似文献
997.
Mascha de Kok Caroline NA Frotscher Trudy van der Weijden Alfons GH Kessels Carmen D Dirksen Cornelis JH van de Velde Jan A Roukema Antoine VRJ Bell Fred W van der Ent Maarten F von Meyenfeldt 《BMC cancer》2007,7(1):117
Background
Whereas ultra-short stay (day care or 24 hour hospitalisation) following breast cancer surgery was introduced in the US and Canada in the 1990s, it is not yet common practice in Europe. This paper describes the design of the MaDO study, which involves the implementation of ultra short stay admission for patients after breast cancer surgery, and evaluates whether the targets of the implementation strategy are reached. The ultra short stay programme and the applied implementation strategy will be evaluated from the economic perspective. 相似文献998.
Pinkney AE Harshbarger JC May EB Melancon MJ 《Environmental toxicology and chemistry / SETAC》2001,20(6):1196-1205
Associations between contaminant exposure and liver and skin tumor prevalence were evaluated in brown bullheads (Ameiurus nebulosus) from the tidal Potomac River, USA, watershed. Thirty bullheads (> or = age 3) were collected from Quantico embayment, near a Superfund site that released organochlorine contaminants; Neabsco Creek, a tributary with petroleum inputs from runoff and marinas; and Anacostia River (spring and fall), an urban tributary designated as a Chesapeake Bay region of concern, that was contaminated with polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and organochlorine pesticides. Fish were collected from the Tuckahoe River, as a reference. Cytochrome P450 activity, bile PAH metabolites, and muscle organochlorine pesticide and PCB concentrations were measured in randomly selected individuals and sediment contaminants were analyzed. We found statistically significant differences in liver tumor prevalences: Anacostia (spring), 50%; Anacostia (fall), 60%; Neabsco, 17%; Quantico, 7%; and Tuckahoe, 10%. Skin tumor prevalences were significantly different: Anacostia (spring), 37%; Anacostia (fall), 10%; Neabsco, 3%; Quantico, 3%; and Tuckahoe, 0%. Tumor prevalence in Anacostia bullheads warrants concern and was similar to those at highly contaminated sites in the Great Lakes. Evidence was found of higher PAH exposure in Anacostia fish but a cause-effect linkage could not be established. Fish tumor surveys, with histopathologic examination of internal and external organs, are recommended for monitoring the status of regions of concern. 相似文献
999.
K Kj?ller JK McLaughlin S Friis WJ Blot L Mellemkjaer C H?gsted JF Winther JH Olsen 《Pediatrics》1998,102(5):1112-1115
OBJECTIVE: To examine the occurrence of esophageal disorders, connective tissue diseases, and congenital malformations in children of mothers with breast implants. METHODS: Nationwide register-based follow-up study of all offspring born during 1977 to 1992 to a cohort of 1135 women with breast implants for cosmetic reasons and to a comparison cohort of 7071 women who underwent breast reduction surgery. Cause-specific hospi-talization rates among offspring, relative to those of the general population, were calculated from the Danish National Registry of Patients. RESULTS: Among the 939 children of mothers with breast implants, higher rates of esophageal disorders were observed, but the excess was similar for those born before versus after the implant surgery. Higher than expected hospitalization rates for these conditions were also observed among 3906 children of women who underwent breast reduction surgery. No significant increases in connective tissue diseases or congenital malformations were observed in either the breast implant or breast reduction cohorts. CONCLUSIONS: This first epidemiologic cohort study provides no evidence that silicone breast implants affect risks of esophageal or other disorders in children of the implantees. Rather, the observed risk pattern suggests that a lower threshold exists among both groups of women who have undergone cosmetic breast surgery in seeking professional medical care for problems normally solved outside the hospital. 相似文献
1000.
BJ Smit JH Kok LS de Vries AG van Wassenaer FW Dekker BW Ongerboer de Visser 《Pediatrics》1998,101(5):865-869
OBJECTIVE: To study the effect of L-thyroxine supplementation on neurologic maturation in very preterm infants with transient hypothyroxinemia. DESIGN: Randomized, double-blind, placebo-controlled, L-thyroxine supplementation trial. SETTING: Level III neonatal intensive care unit. SUBJECTS: A total of 200 infants <30 weeks' gestational age. INTERVENTION: Subjects were randomly assigned to receive L-thyroxine (8 microg/kg birth weight per day) or a placebo during the first 6 weeks of life. METHODS: Median nerve somatosensory evoked potentials were recorded, measuring cortical N1 peak latency at 2 weeks of age, at term, and at 6 months (corrected) age. RESULTS: Cortical N1 peak latency was not decreased significantly in the L-thyroxine group compared with the placebo group throughout the study period. CONCLUSION: L-Thyroxine supplementation during the first 6 weeks of life did not decrease cortical N1 peak latency in infants of <30 weeks' gestational age. 相似文献