全文获取类型
收费全文 | 4343篇 |
免费 | 216篇 |
国内免费 | 29篇 |
专业分类
耳鼻咽喉 | 52篇 |
儿科学 | 102篇 |
妇产科学 | 142篇 |
基础医学 | 480篇 |
口腔科学 | 126篇 |
临床医学 | 302篇 |
内科学 | 870篇 |
皮肤病学 | 65篇 |
神经病学 | 413篇 |
特种医学 | 196篇 |
外科学 | 760篇 |
综合类 | 19篇 |
一般理论 | 1篇 |
预防医学 | 408篇 |
眼科学 | 78篇 |
药学 | 286篇 |
中国医学 | 2篇 |
肿瘤学 | 286篇 |
出版年
2023年 | 19篇 |
2022年 | 73篇 |
2021年 | 120篇 |
2020年 | 61篇 |
2019年 | 84篇 |
2018年 | 93篇 |
2017年 | 81篇 |
2016年 | 129篇 |
2015年 | 138篇 |
2014年 | 156篇 |
2013年 | 230篇 |
2012年 | 349篇 |
2011年 | 340篇 |
2010年 | 183篇 |
2009年 | 181篇 |
2008年 | 289篇 |
2007年 | 258篇 |
2006年 | 262篇 |
2005年 | 228篇 |
2004年 | 219篇 |
2003年 | 156篇 |
2002年 | 177篇 |
2001年 | 40篇 |
2000年 | 65篇 |
1999年 | 53篇 |
1998年 | 22篇 |
1997年 | 27篇 |
1996年 | 28篇 |
1995年 | 35篇 |
1994年 | 25篇 |
1993年 | 20篇 |
1992年 | 42篇 |
1991年 | 38篇 |
1990年 | 46篇 |
1989年 | 39篇 |
1988年 | 32篇 |
1987年 | 24篇 |
1986年 | 21篇 |
1985年 | 21篇 |
1984年 | 17篇 |
1983年 | 12篇 |
1982年 | 11篇 |
1981年 | 11篇 |
1980年 | 15篇 |
1979年 | 13篇 |
1978年 | 16篇 |
1977年 | 9篇 |
1975年 | 8篇 |
1974年 | 7篇 |
1973年 | 8篇 |
排序方式: 共有4588条查询结果,搜索用时 31 毫秒
1.
2.
Anna C. Rienmüller Sandro M. Krieg Franziska A. Schmidt Elias L. Meyer Bernhard Meyer 《The spine journal》2019,19(1):113-120
Background Context
The concept of dynamic stabilization (DS) of the lumbar spine for treatment of degenerative instability has been introduced almost two decades ago. Dynamic stabilization follows the principle of controlling movement in the coronal plane by providing load transfer of the spinal segment without fusion and, at the same time, reducing side effects such as adjacent segment disease (ASD). So far, only little is known about revision rates after DS due to ASD and screw loosening (SL).Purpose
The present study aimed to evaluate the longitudinal revision rates following dynamic pedicle screw stabilization in the lumbar spine and to determine specific risk factors predictive for ASD, SL, and overall reoperation in a large cohort with considerable follow-up.Design
We carried out a post hoc analysis of a prospectively collected database in a level I spine center.Patients Example
The patient sample comprised 283 (151 female/132 male) consecutive patients suffering from painful degenerative lumbar segmental instability with or without spinal stenosis who underwent DS of the lumbar spine (Ulrich Cosmic, Ulrich Medical, Ulm, Germany) between January 2008 and December 2011.Outcome Measures
Longitudinal reoperation rate and risk factors predictive for revision surgery were evaluated.Methods
We analyzed the longitudinal reoperation rate due to ASD and SL and overall reoperation. Risk factors such as age, gender, body mass index, lumbar lordosis (LL), number of segments, and number of previous surgeries were taken into account. Regular and mixed model logistic regressions were performed to determine risk factors for revision surgery on a patient and on a screw level.Results
The mean age was 65.7±10.2 years (range 31–88). One hundred thirty-two patients were stabilized in 1 segment, 134 in 2 segments, 15 in 3 segments, and 2 patients in 4 segments. Reoperation rate for ASD and SL after 1 year was 7.4 %, after 2 years was 15.0%, and after a mean follow-up of 51.4±15 months was 22.6%. Reasons for revision were SL in 19 cases (6.6%), ASD in 39 cases (13.7%), SL and ASD in 6 cases, hematoma in 2 cases (0.7%), cerebrospinal fluid fistulae in 3 cases (1.1%), infection in 6 cases (2.1%), and implant failure in 1 case (0.4%). The patients' age, the number of stabilized segments, and the number of previous surgeries and postoperative LL had a significant influence on the probability for revision surgery.Conclusions
Reoperation rates after DS of the lumbar spine are comparable with rigid fixations. The younger the patient and the more segments are involved, the lower the LL and the more previous surgeries were found, the higher was the risk of revision. Risk of revision was almost twice as high in men compared with women. We therefore conclude that for clear clinical indication and careful evaluation of preoperative imaging data, DS using the Cosmic system seems to be a possible option. The presented data will help to further tailor indication and patient selection. 相似文献3.
According to the current nutritional recommendations issued by professional diabetes and nutrition associations, diabetic patients should keep to a diet consisting of 45–60% carbohydrates, 10–20% protein, and not more than 35% fat. However, not all of these nutritional recommendations are evidence based. For example, current studies show that the intake of insoluble roughage may be underrepresented. It is also possible that diabetic patients could benefit from keeping to the lower end of the recommended range for carbohydrates (45%) and the upper end of the range advised for protein (20%). 相似文献
4.
3D FEA of cemented steel, glass and carbon posts in a maxillary incisor. 总被引:12,自引:0,他引:12
Alessandro Lanza Raffaella Aversa Sandro Rengo Davide Apicella Antonio Apicella 《Dental materials》2005,21(8):709-715
OBJECTIVES: A comparative study on the stress distribution in the dentine and cement layer of an endodontically treated maxillary incisor has been carried out by using Finite Element Analysis (FEA). The role of post and cement rigidity on reliability of endodontic restorations is discussed. METHODS: A 3D FEM model (13,272 elements and 15,152 nodes) of a central maxillary incisor is presented. A chewing static force of 10 N was applied at 125 degree angle with the tooth longitudinal axis at the palatal surface of the crown. Steel, carbon and glass fiber posts have been considered. The differences in occlusal load transfer ability when steel, carbon and glass posts, fixed to root canal using luting cements of different elastic moduli (7.0 and 18.7 GPa) are discussed. RESULTS AND SIGNIFICANCE: The more stiff systems (steel and carbon posts) have been evaluated to work against the natural function of the tooth. Maximum Von Mises equivalent stress values ranging from 7.5 (steel) to 5.4 and 3.6 MPa (respectively, for carbon posts fixed with high and low cement moduli) and to 2.2 MPa (either for glass posts fixed with high and low cement moduli) have been observed under a static masticatory load of 10 N. A very stiff post works against the natural function of the tooth creating zones of tension and shear both in the dentine and at the interfaces of the luting cement and the post. Stresses in static loading do not reach material (dentine and cement) failure limits, however, they significantly differ leading to different abilities of the restored systems to sustain fatigue loading. The influence of the cement layer elasticity in redistributing the stresses has been observed to be less relevant as the post flexibility is increased. 相似文献
5.
P K Kohl 《Zeitschrift für Hautkrankheiten》1989,64(5):403-405
Modern identification of Neisseria gonorrhoeae may be either accomplished by direct detection of gonococcal antigen, i.e. without microbiological culturing, or, following culturing, by rapid culture confirmation. The direct detection of gonococcal antigen in an enzyme immuno-assay (Gonozyme) shows reduced specifity especially with mixed microbial flora, and decreased sensitivity with small numbers of organisms. Culture confirmation may be achieved by a rapid sugar degradation test (API----quadFERM+), by specific enzyme detection using chromogenic substrates (Gonochek II), or by demonstration of protein I specific for Neisseria gonorrhoeae by means of monoclonal antibodies (Mikrotrak, Phadebact monoclonal GC, Gonogen II). Detection of protein I is highly sensitive and specific in both the tests of immunofluorescence and coagglutination. 相似文献
6.
Dozent Dr. med. habil. Hans Kohl 《Journal of molecular medicine (Berlin, Germany)》1940,19(8):181-182
Ohne Zusammenfassung 相似文献
7.
Angelo M. Carella Sandro Nati Paolo Carlier Daniela Pierluigi Domenico Giordano Angela Congiu Gino Santini Daniele Scarpati Salvina Barra Renzo Corvo Vito Vitale Maria R. Raffo Raffaella Cerri Marco Risso Mauro Spriano Renato Vimercati Ester Pungolino Andrea Bacigalupo Eugenio Damasio 《Leukemia & lymphoma》1991,5(1):43-47
Forty consecutive adult patients under the age of 50 with acute non-lymphoblastic leukemia (ANLL) in first complete remission, underwent autologous bone marrow transplantation (ABMT) between March 1984 and April 1990. The conditioning regimen employed included cyclophosphamide and total body irradiation, followed by the administration of unpurged ABMT. The median time from diagnosis to transplant was 7 months (3-15 months), and the median time from complete remission to ABMT was 4 months (range 3-9 months). Twenty-two (51%) patients remain in complete remission 6-81 months (median 24 months) after ABMT.
The causes of death were, recurrent leukemia (11 patients), parenchymal toxicities such as acute respiratory distress syndrome and veno-occlusive disease (3 patients), hemorrhage (2 patients) and infection (2 patients). Eleven patients relapsed after 3-12 months (median 5 months). This study has produced survival data comparable to those of other institutions employing TBI for either allo or autotransplants. 相似文献
The causes of death were, recurrent leukemia (11 patients), parenchymal toxicities such as acute respiratory distress syndrome and veno-occlusive disease (3 patients), hemorrhage (2 patients) and infection (2 patients). Eleven patients relapsed after 3-12 months (median 5 months). This study has produced survival data comparable to those of other institutions employing TBI for either allo or autotransplants. 相似文献
8.
9.
Fetal transesophageal echocardiography: clinical introduction as a monitoring tool during cardiac intervention in a human fetus. 总被引:2,自引:0,他引:2
T Kohl A Müller K Tchatcheva S Achenbach U Gembruch 《Ultrasound in obstetrics & gynecology》2005,26(7):780-785
Because of insufficient imaging by maternal transabdominal fetal echocardiography (TAE) in a human fetus with aortic atresia, imperforate atrial septum and progressive cardiac failure, we assessed the feasibility of fetal transesophageal echocardiography (TEE) as a monitoring tool during fetal cardiac intervention at 24 + 6 weeks of gestation. Percutaneous fetoscopic intraesophageal deployment of the ultrasound catheter was achieved and did not result in any maternal or fetal complications. Fetal TEE permitted substantially clearer definition of fetal cardiac anatomy and intracardiac device manipulations than conventional maternal TAE. Despite the employment of various devices, no sufficiently large opening could be achieved within the atrial septum. Although the fetus tolerated the procedure remarkably well and satisfactory fetoplacental flow could be documented at the end of the procedure, the fetus died from progressive cardiac failure 3 days after the intervention. Fetoscopic TEE is feasible in the human fetus and permits substantially clearer definition of fetal cardiac anatomy and intracardiac manipulations than conventional maternal TAE. Based on the observation of spontaneous closure of multiple iatrogenic perforations of the atrial septum, specialized devices are required in order to improve the technical success rate of septoplasty methods and hence the survival odds of these high-risk patients. 相似文献
10.
Physical fitness and all-cause mortality. A prospective study of healthy men and women 总被引:45,自引:9,他引:36
We studied physical fitness and risk of all-cause and cause-specific mortality in 10,224 men and 3120 women who were given a preventive medical examination. Physical fitness was measured by a maximal treadmill exercise test. Average follow-up was slightly more than 8 years, for a total of 110,482 person-years of observation. There were 240 deaths in men and 43 deaths in women. Age-adjusted all-cause mortality rates declined across physical fitness quintiles from 64.0 per 10,000 person-years in the least-fit men to 18.6 per 10,000 person-years in the most-fit men (slope, -4.5). Corresponding values for women were 39.5 per 10,000 person-years to 8.5 per 10,000 person-years (slope, -5.5). These trends remained after statistical adjustment for age, smoking habit, cholesterol level, systolic blood pressure, fasting blood glucose level, parental history of coronary heart disease, and follow-up interval. Lower mortality rates in higher fitness categories also were seen for cardiovascular disease and cancer of combined sites. Attributable risk estimates for all-cause mortality indicated that low physical fitness was an important risk factor in both men and women. Higher levels of physical fitness appear to delay all-cause mortality primarily due to lowered rates of cardiovascular disease and cancer. 相似文献