全文获取类型
收费全文 | 8082篇 |
免费 | 517篇 |
国内免费 | 7篇 |
专业分类
耳鼻咽喉 | 33篇 |
儿科学 | 239篇 |
妇产科学 | 162篇 |
基础医学 | 990篇 |
口腔科学 | 87篇 |
临床医学 | 990篇 |
内科学 | 1508篇 |
皮肤病学 | 64篇 |
神经病学 | 801篇 |
特种医学 | 266篇 |
外科学 | 915篇 |
综合类 | 430篇 |
一般理论 | 5篇 |
预防医学 | 986篇 |
眼科学 | 68篇 |
药学 | 498篇 |
中国医学 | 7篇 |
肿瘤学 | 557篇 |
出版年
2023年 | 67篇 |
2022年 | 91篇 |
2021年 | 197篇 |
2020年 | 129篇 |
2019年 | 199篇 |
2018年 | 232篇 |
2017年 | 158篇 |
2016年 | 174篇 |
2015年 | 207篇 |
2014年 | 326篇 |
2013年 | 409篇 |
2012年 | 578篇 |
2011年 | 682篇 |
2010年 | 327篇 |
2009年 | 292篇 |
2008年 | 597篇 |
2007年 | 565篇 |
2006年 | 527篇 |
2005年 | 489篇 |
2004年 | 466篇 |
2003年 | 385篇 |
2002年 | 368篇 |
2001年 | 111篇 |
2000年 | 90篇 |
1999年 | 103篇 |
1998年 | 91篇 |
1997年 | 70篇 |
1996年 | 60篇 |
1995年 | 55篇 |
1994年 | 34篇 |
1993年 | 23篇 |
1992年 | 47篇 |
1991年 | 34篇 |
1990年 | 36篇 |
1989年 | 31篇 |
1988年 | 33篇 |
1987年 | 26篇 |
1986年 | 22篇 |
1985年 | 31篇 |
1984年 | 26篇 |
1983年 | 17篇 |
1982年 | 13篇 |
1981年 | 14篇 |
1980年 | 18篇 |
1979年 | 10篇 |
1977年 | 13篇 |
1976年 | 14篇 |
1974年 | 11篇 |
1972年 | 9篇 |
1966年 | 9篇 |
排序方式: 共有8606条查询结果,搜索用时 15 毫秒
71.
72.
Transplanted neural stem cells survive,differentiate, and improve neurological motor function after experimental traumatic brain injury 总被引:45,自引:0,他引:45
Riess P Zhang C Saatman KE Laurer HL Longhi LG Raghupathi R Lenzlinger PM Lifshitz J Boockvar J Neugebauer E Snyder EY McIntosh TK 《Neurosurgery》2002,51(4):1043-52; discussion 1052-4
OBJECTIVE: Using the neural stem cell (NSC) clone C17.2, we evaluated the ability of transplanted murine NSCs to attenuate cognitive and neurological motor deficits after traumatic brain injury. METHODS: Nonimmunosuppressed C57BL/6 mice (n = 65) were anesthetized and subjected to lateral controlled cortical impact brain injury (n = 52) or surgery without injury (sham operation group, n = 13). At 3 days postinjury, all brain-injured animals were reanesthetized and randomized to receive stereotactic injection of NSCs or control cells (human embryonic kidney cells) into the cortex-hippocampus interface in either the ipsilateral or the contralateral hemisphere. One group of animals (n = 7) was killed at either 1 or 3 weeks postinjury to assess NSC survival in the acute posttraumatic period. Motor function was evaluated at weekly intervals for 12 weeks in the remaining animals, and cognitive (i.e., learning) deficits were assessed at 3 and 12 weeks after transplantation. RESULTS: Brain-injured animals that received either ipsilateral or contralateral NSC transplants showed significantly improved motor function in selected tests as compared with human embryonic kidney cell-transplanted animals during the 12-week observation period. Cognitive dysfunction was unaffected by transplantation at either 3 or 12 weeks postinjury. Histological analyses showed that NSCs survive for as long as 13 weeks after transplantation and were detected in the hippocampus and/or cortical areas adjacent to the injury cavity. At 13 weeks, the NSCs transplanted ipsilateral to the impact site expressed neuronal (NeuN) or astrocytic (glial fibrillary acidic protein) markers but not markers of oligodendrocytes (2'3'cyclic nucleotide 3'-phosphodiesterase), whereas the contralaterally transplanted NSCs expressed neuronal but not glial markers (double-labeled immunofluorescence and confocal microscopy). CONCLUSION: These data suggest that transplanted NSCs can survive in the traumatically injured brain, differentiate into neurons and/or glia, and attenuate motor dysfunction after traumatic brain injury. 相似文献
73.
Intrarater and interrater reliability of assessment of lumbar multifidus muscle thickness using rehabilitative ultrasound imaging 总被引:1,自引:0,他引:1
Wallwork TL Hides JA Stanton WR 《The Journal of orthopaedic and sports physical therapy》2007,37(10):608-612
STUDY DESIGN: Within-session intrarater and interrater reliability study. OBJECTIVE: To establish the intrarater and interrater reliability of thickness measurements of the multifidus muscle in a parasagittal plane, conducted by an experienced ultrasound operator and a novice assessor. BACKGROUND: There is considerable evidence for the important role of the multifidus muscle in segmental stabilization of the lumbar spine. The cross-sectional area of the multifidus muscle has been assessed in healthy subjects and patients with low back pain using real-time ultrasound imaging. However, few studies have measured the thickness of the multifidus muscle using a parasagittal view. METHODS AND MEASURES: The thickness of the multifidus muscle was measured at rest, using real-time ultrasound imaging, in 10 subjects without a history of low back pain, at the levels of the L2-3 and L4-5 zygapophyseal joints. The measure was carried out 3 times at each level by 2 assessors (1 experienced, 1 novice). Intrarater (model 3) and interrater (model 2) reliability was assessed by calculation of an F statistic (analysis of variance), the intraclass correlation coefficient (ICC), and the standard error of measurement (SEM). RESULTS: On the basis of an average of 3 trials, the 2 operators showed very high interrater agreement on the measurement of thicknesses at the L2-3 level (ICC2,3 = 0.96; 95% CI: 0.84 to 0.99) and the L4-5 vertebral level (ICC2,3 = 0.97; 95% CI: 0.87 to 0.99), with no systematic differences in muscle size across operators (P > .05). Interrater reliability was relatively lower for the L2-3 level (ICC2,1 = 0.85; 95% CI: 0.51 to 0.96) than the L4-5 level (ICC2,1 = 0.87; 95% CI: 0.52 to 0.97) when a single trial per rater was used, but these values still indicated a high level of agreement. In addition, the novice and experienced operator produced reliable intrarater measurements at L2-3 (ICC3,1 = 0.89; 95% CI: 0.72 to 0.97 and 0.94; 95% CI: 0.86 to 0.99) and at L4-5 (ICC3,1 = 0.88; 95% CI: 0.68 to 0.97 and 0.95; 95% CI: 0.86 to 0.99), with no systematic differences in muscle size across trials (P > .05). The consistently low SEM values also indicate low measurement error. CONCLUSION: A novice and an experienced assessor were both able to reliably perform this measure at rest for 2 vertebral levels using real-time ultrasound imaging. An average of 3 trials produced higher interrater reliability scores, though using a single trial per rater was also reliable. 相似文献
74.
75.
Perioperative cardiac arrests in children between 1988 and 2005 at a tertiary referral center: a study of 92,881 patients 总被引:2,自引:0,他引:2
Flick RP Sprung J Harrison TE Gleich SJ Schroeder DR Hanson AC Buenvenida SL Warner DO 《Anesthesiology》2007,106(2):226-37; quiz 413-4
BACKGROUND: The objective of this study was to determine the incidence and outcome of perioperative cardiac arrest (CA) in children younger than 18 yr undergoing anesthesia for noncardiac and cardiac procedures at a tertiary care center. METHODS: After institutional review board approval (Mayo Clinic, Rochester, Minnesota), all patients younger than 18 yr who had perioperative CA between November 1, 1988, and June 30, 2005, were identified. Perioperative CA was defined as a need for cardiopulmonary resuscitation or death during anesthesia care. A cardiac procedure was defined as a surgical procedure involving the heart or great vessels requiring an incision. RESULTS: A total of 92,881 anesthetics were administered during the study period, of which 4,242 (5%) were for the repair of congenital heart malformations. The incidence of perioperative CA during noncardiac procedures was 2.9 per 10,000, and the incidence during cardiac procedures was 127 per 10,000. The incidence of perioperative CA attributable to anesthesia was 0.65 per 10,000 anesthetics, representing 7.5% of the 80 perioperative CAs. Both CA incidence and mortality were highest among neonates (0-30 days of life) undergoing cardiac procedures (incidence: 435 per 10,000; mortality: 389 per 10,000). Regardless of procedure type, most patients who experienced perioperative CA (88%) had congenital heart disease. CONCLUSION: The majority of perioperative CAs were caused by factors not attributed to anesthesia, in distinction to some recent reports. The incidence of perioperative CA is many-fold higher in children undergoing cardiac procedures, suggesting that definition of case mix is necessary to accurately interpret epidemiologic studies of perioperative CA in children. 相似文献
76.
Murray T Cooperman DR Thompson GH Ballock RT 《American journal of orthopedics (Belle Mead, N.J.)》2007,36(2):82-84
Although many studies have analyzed the success rates of closed reduction and spica casting for the treatment of developmental dysplasia of the hip (DDH) in children, the definition of success for this procedure is not standardized in the literature. We retrospectively reviewed our experience with closed reduction for treatment of DDH in 30 children (35 hips) over an 8-year period to determine the success rates of this procedure on the basis of how success is defined. In only 1 patient (2 hips, 6%) were the hips unable to be concentrically reduced with sufficient stability at the time of closed reduction. In 10 (30%) of the other 33 hips, the acetabulum failed to develop sufficiently after closed reduction, and a secondary surgery was required a mean of 22 months after cast removal. Four (12%) of the 33 hips developed radiographic evidence of avascular necrosis. Therefore, the success rate of closed reduction for DDH varies markedly depending on how success is defined. 相似文献
77.
Persistent systemic inflammatory response syndrome is predictive of nosocomial infection in trauma 总被引:5,自引:0,他引:5
Bochicchio GV Napolitano LM Joshi M Knorr K Tracy JK Ilahi O Scalea TM 《The Journal of trauma》2002,53(2):245-50; discussion 250-1
BACKGROUND: Admission systemic inflammatory response syndrome (SIRS) score has been previously reported to be an accurate predictor of infection and outcome in trauma. However, these data were limited to only one SIRS score at admission. A prior study in surgical intensive care unit (ICU) patients reported that the SIRS score on ICU day 2 declined after completion of resuscitation, and was a more accurate predictor of outcome. Our objective in this follow-up study was to prospectively evaluate the utility of daily SIRS scores in prediction of nosocomial infection and outcome in high-risk trauma patients. METHODS: Prospective data were collected on 702 consecutive trauma patients admitted over a 12-month period to the ICU. SIRS scores were calculated daily. Centers for Disease Control and Prevention guidelines were used for the diagnosis of infection. Multivariate linear regression was used for statistical analysis. RESULTS: Five hundred seventy-three (82%) patients sustained blunt injuries and 129 (18%) sustained penetrating injuries. The mean age was 43 +/- 21 years, with an overall mortality of 11.4%. Two hundred ninety (41.3%) of the study patients acquired a nosocomial infection (respiratory site most common), with an associated mortality rate of 12.4%. SIRS (defined as SIRS score >/= 2) on hospital days 3 through 7 was a significant predictor of nosocomial infection and hospital length of stay. Persistent SIRS to hospital day 7 was associated with a significant risk for increased mortality (relative risk, 4.7; 95% confidence interval, 1.41-12.87; p = 0.047). CONCLUSION: Persistent SIRS is predictive of nosocomial infection in trauma. Daily monitoring of SIRS scores is easily accomplished and should be considered in all high-risk trauma patients. Persistent SIRS in trauma should initiate early diagnostic interventions for determination of source of infection, and consideration of early empiric antimicrobial therapy. 相似文献
78.
Joachim H. Ix Mary L. Biggs Kenneth Mukamal Luc Djousse David Siscovick Russell Tracy Ronit Katz Joseph A. Delaney Paulo Chaves Dena E. Rifkin Jan M. Hughes-Austin Pranav S. Garimella Mark J. Sarnak Michael G. Shlipak Jorge R. Kizer 《Journal of the American Society of Nephrology : JASN》2015,26(10):2494-2503
Tubulointerstitial fibrosis is common with ageing and strongly prognostic for ESRD but is poorly captured by eGFR or urine albumin to creatinine ratio (ACR). Higher urine levels of procollagen type III N-terminal propeptide (PIIINP) mark the severity of tubulointerstitial fibrosis in biopsy studies, but the association of urine PIIINP with CKD progression is unknown. Among community-living persons aged ≥65 years, we measured PIIINP in spot urine specimens from the 1996 to 1997 Cardiovascular Health Study visit among individuals with CKD progression (30% decline in eGFR over 9 years, n=192) or incident ESRD (n=54) during follow-up, and in 958 randomly selected participants. We evaluated associations of urine PIIINP with CKD progression and incident ESRD. Associations of urine PIIINP with cardiovascular disease, heart failure, and death were evaluated as secondary end points. At baseline, mean age (±SD) was 78±5 years, mean eGFR was 63±18 ml/min per 1.73 m2, and median urine PIIINP was 2.6 (interquartile range, 1.4–4.2) μg/L. In a case-control study (192 participants, 231 controls), each doubling of urine PIIINP associated with 22% higher odds of CKD progression (adjusted odds ratio, 1.22; 95% confidence interval, 1.00 to 1.49). Higher urine PIIINP level was also associated with incident ESRD, but results were not significant in fully adjusted models. In a prospective study among the 958 randomly selected participants, higher urine PIIINP was significantly associated with death, but not with incident cardiovascular disease or heart failure. These data suggest higher urine PIIINP levels associate with CKD progression independently of eGFR and ACR in older individuals. 相似文献
79.
Tracy Y Zhu James F Griffith Ling Qin Vivian WY Hung Tsz‐Ning Fong Sze‐Ki Au Xiao Lin Tang Anthony W Kwok Ping‐Chung Leung Edmund K Li Lai‐Shan Tam 《Journal of bone and mineral research》2013,28(4):794-806
The purpose of this work was to investigate the volumetric bone mineral density (vBMD), bone microstructure, and mechanical indices of the distal radius in female patients with rheumatoid arthritis (RA). We report a cross‐sectional study of 66 middle‐aged female RA patients and 66 age‐matched healthy females. Areal BMD (aBMD) of the hip, lumbar spine, and distal radius was measured by dual‐energy X‐ray absorptiometry (DXA). High‐resolution peripheral quantitative computed tomography (HR‐pQCT) was performed at the distal radius, yielding vBMD, bone microstructure, and mechanical indices. Cortical and trabecular vBMD were 3.5% and 10.7% lower, respectively, in RA patients than controls, despite comparable aBMD. Trabecular microstructural indices were –5.7% to –23.1% inferior, respectively, in RA patients compared to controls, with significant differences in trabecular bone volume fraction, separation, inhomogeneity, and structural model index. Cortical porosity volume and percentage were 128% and 93% higher, respectively, in RA patients, with stress being distributed more unevenly. Fourteen RA patients had exaggerated periosteal bone apposition primarily affecting the ulnovolar aspect of the distal radius. These particular patients were more likely to have chronic and severe disease and coexisting wrist deformity. The majority of the differences in density and microstructure between RA patients and controls did not depend on menstrual status. Recent exposure to glucocorticoids did not significantly affect bone density and microstructure. HR‐pQCT provides new insight into inflammation‐associated bone fragility in RA. It detects differences in vBMD, bone microstructure, and mechanical indices that are not captured by DXA. At the distal radius, deterioration in density and microstructure in RA patients involved both cortical and trabecular compartments. Excessive bone resorption appears to affect cortical more than trabecular bone at distal radius, particularly manifested as increased cortical porosity. Ulnovolar periosteal apposition of the distal radius is a feature of chronic, severe RA with wrist deformity. © 2013 American Society for Bone and Mineral Research. 相似文献
80.
HOCK LEONG EE MBBS MRCP CHEE LEOK GOH MBBS FRCP KHOO ES-Y. CHAN PHD POR ANG MBBS MRCP 《Dermatologic surgery》2006,32(1):34-40
BACKGROUND: Acquired bilateral nevus of Ota-like macules (Hori's nevus) is a common dyschromatosis among Asian women. Q-switched lasers have been used successfully as a treatment modality. OBJECTIVE: The purpose of this study was to compare the efficacy of using the Q-switched 532 nm neodymium:yttrium-aluminum-garnet (Nd:YAG) laser followed by the 1,064 nm laser versus the Q-switched 1,064 nm Nd:YAG laser alone in the treatment of Hori's nevus. METHODS: This is a prospective left-right comparative study. Ten women with bilateral Hori's nevus were recruited and treated with a combination of the Q-switched 532 and 1,064 nm Nd:YAG lasers on the right cheek and the Q-switched 1,064 nm Nd:YAG laser alone on the left cheek. Only one laser treatment session was performed. The degree of pigmentation was objectively recorded with a mexameter. Subjective assessment was made by both patients and two blinded, nontreating dermatologists. RESULTS: At 6 months, there was a statistically significant difference (p = .009) of 35.10 points using objective mexameter measurements between the two sides, favoring the side treated with a combination of 532 and 1,064 nm laser treatment. Subjective grading by the patients and blinded dermatologists also confirmed that combination therapy was more successful after one treatment. Although combination treatment had a higher incidence of mild postinflammatory changes, this disappeared within 2 months. CONCLUSIONS: Concurrent use of the Q-switched 532 nm Nd:YAG laser in combination with the 1,064 nm laser is more effective in pigment clearance than the Q-switched 1,064 nm Nd:YAG laser alone for Hori's nevi. 相似文献