全文获取类型
收费全文 | 22695篇 |
免费 | 1678篇 |
国内免费 | 89篇 |
专业分类
耳鼻咽喉 | 153篇 |
儿科学 | 770篇 |
妇产科学 | 523篇 |
基础医学 | 3305篇 |
口腔科学 | 328篇 |
临床医学 | 2776篇 |
内科学 | 4997篇 |
皮肤病学 | 480篇 |
神经病学 | 2396篇 |
特种医学 | 386篇 |
外科学 | 2007篇 |
综合类 | 128篇 |
一般理论 | 28篇 |
预防医学 | 2528篇 |
眼科学 | 246篇 |
药学 | 1530篇 |
中国医学 | 43篇 |
肿瘤学 | 1838篇 |
出版年
2024年 | 20篇 |
2023年 | 215篇 |
2022年 | 387篇 |
2021年 | 763篇 |
2020年 | 509篇 |
2019年 | 759篇 |
2018年 | 783篇 |
2017年 | 576篇 |
2016年 | 651篇 |
2015年 | 713篇 |
2014年 | 909篇 |
2013年 | 1189篇 |
2012年 | 1937篇 |
2011年 | 1943篇 |
2010年 | 1036篇 |
2009年 | 872篇 |
2008年 | 1512篇 |
2007年 | 1564篇 |
2006年 | 1539篇 |
2005年 | 1425篇 |
2004年 | 1314篇 |
2003年 | 1162篇 |
2002年 | 1018篇 |
2001年 | 137篇 |
2000年 | 86篇 |
1999年 | 148篇 |
1998年 | 191篇 |
1997年 | 136篇 |
1996年 | 133篇 |
1995年 | 121篇 |
1994年 | 82篇 |
1993年 | 86篇 |
1992年 | 44篇 |
1991年 | 44篇 |
1990年 | 42篇 |
1989年 | 48篇 |
1988年 | 33篇 |
1987年 | 24篇 |
1986年 | 32篇 |
1985年 | 26篇 |
1984年 | 39篇 |
1983年 | 26篇 |
1982年 | 24篇 |
1981年 | 25篇 |
1980年 | 19篇 |
1979年 | 12篇 |
1978年 | 14篇 |
1976年 | 16篇 |
1973年 | 13篇 |
1971年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
61.
Joseph V. Hajnal Ralph Myers Angela Oatridge Jane E. Schwieso Ian R. Young Graeme M. Bydder 《Magnetic resonance in medicine》1994,31(3):283-291
To assess the effect of stimulus correlated motion on the appearance of functional magnetic resonance images, conventional visual and motor protocols were each performed by four normal volunteers and an image co-registration technique was used to retrospectively monitor subject motion. In three studies synthetic data sets were constructed from single baseline images using the positional information obtained from the co-registration procedure. Cumulative difference images were then created from both the synthetic and functional image sets. Stimulus correlated motion was detected in all eight studies and the synthetic cumulative difference images showed striking similarities to the equivalent functional images in each case. 相似文献
62.
Chih-Hung Chien Tzong-Yang Tu Shu-Feng Chien Angela Chung-I Li Mei-Jan Yang An-Suey Shiao Yi-Fen Wang 《台湾医志》2006,105(10):832-838
BACKGROUND/PURPOSE: In the geriatric population, the reliability of pure-tone threshold (PTT) is sometimes poorer than that in young adults because of various reasons. This study assessed the relationship between Mandarin speech reception thresholds (SRTs) and PTTs in the aged and developed SRT as a measure for corroborating PTT. METHODS: This prospective study enrolled 46 consecutive subjects over 60 years of age. The results of SRT and PTT were collected from one ear randomly selected from each subject. Simple linear and multiple regressions were used to determine the correlation and linear regression coefficients between SRTs and PTTs at various frequencies. RESULTS: In the simple regression analysis, the correlation coefficient was highest at 1000 Hz (r = 0.949) and 500 Hz (r = 0.922), followed by 250 Hz (r = 0.850) and 2000 Hz (r = 0.792). In the multiple regression model with SRT as the dependent variable and PTTs as predictor variables, the resultant multiple correlation coefficient R was 0.967, while R2 was 0.936. In this model, PTTs at the frequencies of 500 Hz and 1000 Hz contributed significantly to the variance in SRTs with p values of 0.029 and < 0.001, respectively. These results demonstrated that the Mandarin SRT is strongly associated with PTTs at the frequencies of 500 Hz and 1000 Hz. CONCLUSION: This study established the agreement between Mandarin SRTs and PTTs in the low tone area of speech frequencies in the geriatric population. In clinical settings, SRT test can be rapidly and easily performed and is relatively inexpensive. It is a vital indicator of the accuracy of PTT measurement. 相似文献
63.
64.
Marko Simunovic Eddy Rempel Marc-Erick Thériault Angela Coates Timothy Whelan Eric Holowaty Bernard Langer Mark Levine 《Canadian journal of surgery》2006,49(4):251-258
BACKGROUND: There is a lack of information from Canadian hospitals on the role of hospital characteristics such as procedure volume and teaching status on the survival of patients who undergo major cancer resection. Therefore, we chose to study these relationships using data from patients treated in Ontario hospitals. METHODS: We used the Ontario Cancer Registry from calendar years 1990-2000 to obtain data on patients who underwent surgery for breast, colon, lung or esophageal cancer or who underwent major liver surgery related to a cancer diagnosis between 1990 and 1995 in order to assess the influence of volume of procedures and teaching status of hospitals on in-hospital death rate and long-term survival. For each disease site and before observing patient outcomes data, volume cut-off points were selected to create volume groups with similar numbers of patients. Teaching hospitals were those directly affiliated with a medical school. Logistic regression and proportional hazards models were used to consider the clustering of data at the hospital level and to assess operative death and long-term survival. We also used 4 measures to gauge the degree of procedure regionalization across the province including (1) the number of hospitals performing a procedure; (2) the percentage of patients treated in teaching hospitals; (3) the percentage of rural patients treated in higher volume procedure hospitals; and (4) median distances travelled by patients to receive care. RESULTS: The number of patients in our cohorts who underwent resection of the breast, colon, lung, esophagus or liver was 14 346, 8398, 2698, 629 and 362, respectively. Surgery in a high-volume versus a low-volume hospital did not have a statistically significant influence on the odds of operative death for patients who underwent colon, liver, lung or esophageal cancer resection. The risk of long-term death was increased in low-volume versus high-volume hospitals for patients who underwent resection of the breast (hazard ratio [HR] 1.2, 95% confidence interval [95% CI] 1.0-1.4, p < 0.05), lung (HR 1.3, 95% CI 1.1-1.6, p < 0.01) and liver (HR 1.7, 95% CI 1.0-2.7, p = 0.04). There were no significant differences in the odds of operative (in-hospital) death or risk of long-term death among patients treated in teaching compared with nonteaching hospitals. There was more regionalization of liver, lung and esophageal operations versus breast and colon operations. CONCLUSIONS: Increased hospital procedure volume correlated with improved longterm survival for patients in Ontario who underwent some, but not all, cancer resections, whereas hospital teaching status had no significant impact on patient outcomes. Across the province, further regionalization of care may help improve the quality of some cancer procedures. 相似文献
65.
Jenny E Westin Linda Vercammen Elissa M Strome Christine Konradi M Angela Cenci 《Neuropsychopharmacology》2007,62(7):800-810
BACKGROUND: We examined the activation pattern of extracellular signal-regulated kinase 1 and 2 (ERK1/2) and its dependence on D1 versus D2 dopamine receptors in hemiparkinsonian rats treated with 3,4-dihydroxyphenyl-L-alanine (L-DOPA). METHODS: 6-Hydroxydopamine-lesioned rats were treated acutely or chronically with L-DOPA in combination with antagonists for D1 or D2 receptors. Development of dyskinesia was monitored in animals receiving chronic drug treatment. Phosphorylation of ERK1/2, mitogen- and stress-activated protein kinase-1 (MSK-1), and the levels of FosB/DeltaFosB expression were examined immunohistochemically. RESULTS: L-DOPA treatment caused phosphorylation of ERK1/2 in the dopamine-denervated striatum after acute and chronic administration. Similar levels were observed in matrix and striosomes, and in enkephalin-positive and dynorphin-positive neurons. The severity of dyskinesia was positively correlated with phospho-ERK1/2 levels. Phosphorylation of ERK1/2 and MSK-1 was dose-dependently blocked by SCH23390, but not by raclopride. SCH23390 also inhibited the development of dyskinesia and the induction of FosB/DeltaFosB. CONCLUSIONS: L-DOPA produces pronounced activation of ERK1/2 signaling in the dopamine-denervated striatum through a D1-receptor-dependent mechanism. This effect is associated with the development of dyskinesia. Phosphorylated ERK1/2 is localized to both dynorphinergic and enkephalinergic striatal neurons, suggesting a general role of ERK1/2 as a plasticity molecule during L-DOPA treatment. 相似文献
66.
Treatment of an infected total hip replacement with the PROSTALAC system: Part 1: Infection resolution
下载免费PDF全文
![点击此处可从《Canadian journal of surgery》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Angela Scharfenberger Marcia Clark Guy Lavoie Greg O''''Connor Edward Masson Lauren Beaupre 《Canadian journal of surgery》2007,50(1):24-28
INTRODUCTION: Infection after total hip replacement (THR) is a serious medical complication with significant negative ramifications for both the patient and the health care system. The prosthesis of antibiotic-loaded acrylic cement (PROSTALAC) was designed to treat the joint infection while maintaining functional movement in the hip. METHODS: We identified 28 patients treated for infected THR with the PROSTALAC system, by retrospective chart review. Preoperative and intraoperative cultures were taken to identify the causative organism. After PROSTALAC insertion, patients underwent at least 6 weeks of intravenous (IV) antibiotics. Prior to undergoing posttreatment cultures, patients were required to be antibiotic-free for a minimum of 6 weeks, with normal laboratory values. We defined resolution infection as retention of a joint prosthesis for a minimum of 2 years. RESULTS: Infection was identified in 28 patients in either the joint aspirate or intraoperative cultures. Of these patients, 2 failed to clear infection, requiring repeat PROSTALAC insertion. Two additional patients had positive 48-hour cultures post-second stage, treated with additional IV antibiotics. Retention of the post-PROSTALAC prosthesis is 100% at 2 years. CONCLUSION: PROSTALAC has acceptable infection resolution outcomes and appears effective for treating infected THR. 相似文献
67.
Conventional follicle harvesting techniques for hair transplantation are limited by the available scalp donor hair. The development of an innovative technique of microsurgical single follicular unit extraction has made it possible to exploit body hair grafts for scalp transplantation. This case study reports on 18 months of follow-up on a patient with extensive scalp scarring who underwent a transplantation procedure using donor chest hair. The photographically documented results show a change in the length of the chest hair measuring an average of 4 cm at transplant to 15 cm by 18 months post-transplant. The transplanted chest grafts provided an excellent cosmetic result for hair replacement. 相似文献
68.
Kazumasa Fujitani Jaffer A. Ajani Christopher H. Crane Barry W. Feig Peter W. Pisters Nora Janjan Garrett L. Walsh Stephen G. Swisher Ara A. Vaporciyan David Rice Angela Welch Jackie Baker Josephine Faust Paul F. Mansfield MD 《Annals of surgical oncology》2007,14(4):1305-1311
Background Significant tumor downstaging has been achieved in patients with localized gastric or gastroesophageal adenocarcinoma by induction
chemotherapy and preoperative chemoradiotherapy (CTX–CTXRT). However, the influence of CTX–CTXRT on operative morbidity and
mortality has not yet been clarified. The aim of the present study was to document the frequency and nature of morbidity and
mortality after surgery combined with CTX–CTXRT, and identify factors predictive of postoperative complications in patients
with localized gastric or gastroesophageal adenocarcinoma.
Methods A prospectively collected database on 71 consecutive patients who underwent CTX–CTXRT at M.D. Anderson Cancer Center between
January 1997 and August 2004 was reviewed. Postoperative morbidity and mortality were investigated, and risk factors for overall
complications were identified by multivariate logistic regression analysis.
Results Overall morbidity and mortality rates were 38.0% (27 patients) and 2.8% (2 patients), respectively. Age greater than 60 years
[relative risk 11.3 (95% confidence interval 2.50–50.6)] and body mass index (BMI) of 26 kg/m2 or above [relative risk 4.08 (95% confidence interval 1.08–15.4)] were significant risk factors for overall complications.
Conclusions CTX–CTXRT can be performed safely with an acceptable operative morbidity and a low operative mortality rate in patients with
gastric or gastroesophageal cancer, with careful consideration of added risk associated with age and obesity. 相似文献
69.
Alan J.A. McBride Gustavo M. Cerqueira Marc A. Suchard Angela N. Moreira Richard L. Zuerner Mitermayer G. Reis David A. Haake Albert I. Ko Odir A. Dellagostin 《Infection, genetics and evolution》2009,9(2):196-205
Recent serologic, immunoprotection, and pathogenesis studies identified the Lig proteins as key virulence determinants in interactions of leptospiral pathogens with the mammalian host. We examined the sequence variation and recombination patterns of ligA, ligB, and ligC among 10 pathogenic strains from five Leptospira species. All strains were found to have intact ligB genes and genetic drift accounting for most of the ligB genetic diversity observed. The ligA gene was found exclusively in L. interrogans and L. kirschneri strains, and was created from ligB by a two-step partial gene duplication process. The aminoterminal domain of LigB and the LigA paralog were essentially identical (98.5 ± 0.8% mean identity) in strains with both genes. Like ligB, ligC gene variation also followed phylogenetic patterns, suggesting an early gene duplication event. However, ligC is a pseudogene in several strains, suggesting that LigC is not essential for virulence. Two ligB genes and one ligC gene had mosaic compositions and evidence for recombination events between related Leptospira species was also found for some ligA genes. In conclusion, the results presented here indicate that Lig diversity has important ramifications for the selection of Lig polypeptides for use in diagnosis and as vaccine candidates. This sequence information will aid the identification of highly conserved regions within the Lig proteins and improve upon the performance characteristics of the Lig proteins in diagnostic assays and in subunit vaccine formulations with the potential to confer heterologous protection. 相似文献
70.
Angela Favaro Tatiana Zanetti Elena Tenconi Daniela Degortes Andrea Ronzan Angela Veronese Paolo Santonastaso 《Eating disorders》2004,13(1):61-70
To date, few studies have examined the personality characteristics and clinical predictors of impulsive behaviors in eating disorders (ED). The aim of this work was to study the prevalence of a wide range of impulsive behaviors in a sample of 554 ED subjects and to examine the predictors of these behaviors. Subjects were diagnosed according to DSM-IV criteria as having anorexia nervosa restricting type (ANR; n = 183), anorexia nervosa binge eating/purging type (ANBP; n = 65), bulimia nervosa purging type (BNP; n = 244), and bulimia nervosa nonpurging type (BNNP; n = 62). Nine different types of impulsive behaviors were assessed in these groups. About 55% of the whole sample reported at least one type of impulsive behavior, 35% more than one, and about 13% more than three. According to findings, impulsive and multi-impulsive subjects are characterized by the presence of purging behavior and by specific temperamental features such as high levels of novelty seeking and low persistence. The prediction of impulsive behavior is further improved by considering the presence of a history of childhood abuse, maternal psychiatric morbidity, and some specific psychological symptoms such as maturity fears, perfectionism, depression, and obsessive-compulsive symptoms. The presence of impulsive behavior appears to be associated with overall higher levels of psychiatric symptomatology and eating psychopathology, thus indicating that they are an important feature to be considered in the assessment and treatment of ED. 相似文献