全文获取类型
收费全文 | 236457篇 |
免费 | 13384篇 |
国内免费 | 6882篇 |
专业分类
耳鼻咽喉 | 3531篇 |
儿科学 | 8548篇 |
妇产科学 | 3410篇 |
基础医学 | 17064篇 |
口腔科学 | 5270篇 |
临床医学 | 27985篇 |
内科学 | 40412篇 |
皮肤病学 | 3173篇 |
神经病学 | 11200篇 |
特种医学 | 12632篇 |
外国民族医学 | 35篇 |
外科学 | 40056篇 |
综合类 | 22281篇 |
现状与发展 | 27篇 |
预防医学 | 15161篇 |
眼科学 | 4928篇 |
药学 | 24184篇 |
115篇 | |
中国医学 | 4597篇 |
肿瘤学 | 12114篇 |
出版年
2023年 | 2312篇 |
2022年 | 4099篇 |
2021年 | 9685篇 |
2020年 | 6022篇 |
2019年 | 11814篇 |
2018年 | 6405篇 |
2017年 | 5554篇 |
2016年 | 7506篇 |
2015年 | 10305篇 |
2014年 | 18853篇 |
2013年 | 16449篇 |
2012年 | 19770篇 |
2011年 | 16839篇 |
2010年 | 15470篇 |
2009年 | 14958篇 |
2008年 | 13498篇 |
2007年 | 13562篇 |
2006年 | 11508篇 |
2005年 | 7826篇 |
2004年 | 4065篇 |
2003年 | 3568篇 |
2002年 | 2928篇 |
2001年 | 2279篇 |
2000年 | 1957篇 |
1999年 | 1234篇 |
1998年 | 1627篇 |
1997年 | 1474篇 |
1996年 | 1247篇 |
1995年 | 1293篇 |
1994年 | 1231篇 |
1993年 | 950篇 |
1992年 | 1174篇 |
1991年 | 1038篇 |
1990年 | 1067篇 |
1989年 | 1047篇 |
1988年 | 978篇 |
1987年 | 855篇 |
1986年 | 693篇 |
1985年 | 1620篇 |
1984年 | 1765篇 |
1983年 | 1273篇 |
1982年 | 1374篇 |
1981年 | 1344篇 |
1980年 | 1154篇 |
1979年 | 991篇 |
1978年 | 761篇 |
1977年 | 764篇 |
1976年 | 667篇 |
1974年 | 455篇 |
1973年 | 436篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
《Journal of Cardiovascular Computed Tomography》2021,15(6):492-498
BackgroundCompared with invasive fractional flow reserve (FFR), coronary CT angiography (cCTA) is limited in detecting hemodynamically relevant lesions. cCTA-based FFR (CT-FFR) is an approach to overcome this insufficiency by use of computational fluid dynamics. Applying recent innovations in computer science, a machine learning (ML) method for CT-FFR derivation was introduced and showed improved diagnostic performance compared to cCTA alone. We sought to investigate the influence of stenosis location in the coronary artery system on the performance of ML-CT-FFR in a large, multicenter cohort.MethodsThree hundred and thirty patients (75.2% male, median age 63 years) with 502 coronary artery stenoses were included in this substudy of the MACHINE (Machine Learning Based CT Angiography Derived FFR: A Multi-Center Registry) registry. Correlation of ML-CT-FFR with the invasive reference standard FFR was assessed and pooled diagnostic performance of ML-CT-FFR and cCTA was determined separately for the following stenosis locations: RCA, LAD, LCX, proximal, middle, and distal vessel segments.ResultsML-CT-FFR correlated well with invasive FFR across the different stenosis locations. Per-lesion analysis revealed improved diagnostic accuracy of ML-CT-FFR compared with conventional cCTA for stenoses in the RCA (71.8% [95% confidence interval, 63.0%–79.5%] vs. 54.8% [45.7%–63.8%]), LAD (79.3 [73.9–84.0] vs. 59.6 [53.5–65.6]), LCX (84.1 [76.0–90.3] vs. 63.7 [54.1–72.6]), proximal (81.5 [74.6–87.1] vs. 63.8 [55.9–71.2]), middle (81.2 [75.7–85.9] vs. 59.4 [53.0–65.6]) and distal stenosis location (67.4 [57.0–76.6] vs. 51.6 [41.1–62.0]).ConclusionIn a multicenter cohort with high disease prevalence, ML-CT-FFR offered improved diagnostic performance over cCTA for detecting hemodynamically relevant stenoses regardless of their location. 相似文献
72.
《Diagnostic and interventional imaging》2021,102(10):641-648
PurposeTo evaluate the potential differences in non-target embolization and vessel microsphere filling of a reflux-control microcatheter (RCM) compared to a standard end-hole microcatheter (SEHM) in a swine model.Materials and methodsRadiopaque microspheres were injected with both RCM and SEHM (2.4-Fr and 2.7-Fr) in the kidneys of a preclinical swine model. Transarterial renal embolization procedures with RCM or SEHM were performed in both kidneys of 14 pigs. Renal arteries were selectively embolized with an automated injection protocol of radio-opaque microspheres. Ex-vivo X-ray microtomography images of the kidneys were utilized to evaluate the embolization by quantification of the deposition of injected microspheres in the target vs. the non-target area of injection. X-ray microtomography images were blindly analyzed by five interventional radiologists. The degree of vessel filling and the non-target embolization were quantified using a scale from 1 to 5 for each parameter. An analysis of variance was used to compare the paired scores.ResultsTotal volumes of radio-opaque microspheres injected were similar for RCM (11.5 ± 3.6 [SD] mL; range: 6–17 mL) and SEHM (10.6 ± 5.2 [SD] mL; range: 4–19 mL) (P = 0.38). The voxels enhanced ratio in the target (T) vs. non-target (NT) areas was greater with RCM (T = 98.3% vs. NT = 1.7%) than with SEHM (T = 89% vs. NT = 11%) but the difference was not significant (P = 0.30). The total score blindly given by the five interventional radiologists was significantly different between RCM (12.3 ± 2.1 [SD]; range: 6–15) and the standard catheter (11.3 ± 2.5 [SD]; range: 4–15) (P = 0.0073), with a significant decrease of non-target embolization for RCM (3.8 ± 1.3 [SD]; range: 3.5–4.2) compared to SEHM (3.2 ± 1.5 [SD]; range: 2.9–3.5) (P = 0.014).ConclusionIn an animal model, RCM microcatheters reduce the risk of non-target embolization from 11% to 1.7%, increasing the delivery of microspheres of 98% to the target vessels, compared to SEHM microcatheters. 相似文献
73.
P. Van Camp L. Verstraete B. Van Loon J. Scheerlinck E. Nout 《International journal of oral and maxillofacial surgery》2021,50(5):643-648
This study was undertaken to evaluate the infection rate following orthognathic surgery and to identify possible risk factors. A retrospective study was conducted. Patients undergoing orthognathic surgery from August 1, 2017 to July 31, 2018 were included. The outcome variable was surgical site infection (SSI). All data were analysed with respect to demographics and procedure specifications. A total of 137 patients (mean age 28.5 ± 12.69 years) were included in this study, of whom 20 (14.6%) developed a SSI. The only risk factor identified was the type of surgery: those undergoing mandibular osteotomies (in bilateral sagittal split osteotomy (BSSO) or bimaxillary osteotomies) were far more likely to develop infections. Third molar teeth were removed during orthognathic surgery in 28.5% of the procedures, and a genioplasty was performed in 10.9%. Removal of osteosynthesis material because of infectious reasons was necessary in 10.2% of patients, with a strong association to previous SSI. In conclusion, this study showed an infection rate of 14.6% with no link to any demographic risk factor. Neither the simultaneous removal of third molar teeth nor genioplasty was found to be a risk factor for SSI. For literature comparison purposes, there is a clear need for the international guidelines defining SSI to be used. 相似文献
74.
75.
J.T. Deferm F. Baan R. Schreurs R. Willaert T. Maal G. Meijer 《International journal of oral and maxillofacial surgery》2021,50(1):38-42
Monitoring vascular perfusion of transferred tissue is essential in reconstructive surgery to recognize early flap failure. The aim of this study was to evaluate the ability of a digital surface scanner to detect vascular perfusion disorders through the monitoring of skin colour changes. A total of 160 surface scans of the forearm skin were performed with a TRIOS 3D scanner. Vascular compromise was simulated at different time-points by intermittent occlusion of the blood supply to the forearm skin (first the arterial blood supply and then the venous blood supply). Skin colour changes were examined according to the hue, saturation, and value colour scale. Colour differences were analysed with a paired t-test. Significant differences were observed between the colour of the normal skin and that of the vascular compromised skin (P < 0.01). The surface scanner could distinguish between arterial occlusion and venous congestion (P < 0.01). A digital surface scan is an objective, non-invasive tool to detect early vascular perfusion disorders of the skin. 相似文献
76.
H. Chen R. Bi Z. Hu J. Chen N. Jiang G. Wu Y. Li E. Luo S. Zhu 《International journal of oral and maxillofacial surgery》2021,50(5):635-642
The selection and implementation of a plan for maxillary surgery is of the utmost importance in achieving the desired outcome for the patient undergoing two-jaw orthognathic surgery. Some splint-based and splintless methods, accompanied by computer-assisted techniques, are helpful in improving surgical plan implementation. However, randomized controlled trials focused on this procedure are lacking. This study included 61 patients who underwent bimaxillary surgeries. The patients were randomly assigned to a conventional resin occlusal splint (CROS) group, a digital occlusal splint (DOS) group, or a digital templates (DT) group, in a 1:1:1 ratio. The mean linear distance between the planned and actual postoperative positions of eight selected points on the surfaces of the maxillary teeth was selected as the outcome measure. The distance was significantly smaller in the DT group (1.17 ± 0.66 mm) when compared to both the CROS group (2.55 ± 0.95 mm, P < 0.05) and DOS group (2.15 ± 1.12 mm, P < 0.05). However, the difference between the CROS group and DOS group was not statistically significant. These findings indicate that using digital templates results in the best performance in transferring the surgical plan to the operation environment as compared to the other two types of splints. This suggests that the application of digital templates could provide a reliable treatment option. 相似文献
77.
78.
目的探讨不同手术方法治疗复杂胫骨平台骨折临床疗效。方法选择2016年1月—2018年12月84例复杂胫骨平台骨折患者,随机分组。单侧锁定钢板内固定组选择单侧锁定钢板内固定手术,双侧切口双侧解剖钢板内固定组选择双侧切口双侧解剖钢板内固定。分析手术操作时间、手术失血、平均住院天数以及复杂胫骨平台骨折愈合时间;治疗前后患者视觉模拟评分和Rasmussen膝关节功能评分;膝关节僵硬发生率。结果双侧切口双侧解剖钢板内固定组视觉模拟评分和Rasmussen膝关节功能评分、手术操作时间、手术失血、平均住院天数以及复杂胫骨平台骨折愈合时间、膝关节僵硬发生率和单侧锁定钢板内固定组比较有优势,P<0.05。结论复杂胫骨平台骨折患者实施双侧切口双侧解剖钢板内固定可获得较好效果。 相似文献
79.
《Vaccine》2021,39(33):4742-4750
Allogeneic hematopoietic stem cell transplantation (alloHSCT) results in a loss of humoral immunity and subsequent risk for severe infections. Thus, re-vaccination is required but may fail due to incomplete immune reconstitution. We retrospectively analyzed predictors of immune response to primary vaccination applied according to the EBMT (European Blood and Marrow Transplantation Group) recommendations. Serologic response to vaccination against diphtheria (D), tetanus (T), Bordetella pertussis (aP) and Haemophilus influenzae (Hib) (administrated as combined DTaP-Hib-IPV vaccination) was studied in 84 alloHSCT patients transplanted between 2008 and 2015 (age at alloHSCT: 18.6–70.6 years). All patients with a relapse-free survival of ≥9 months, at least 3 consecutive vaccinations and absence of intravenous immunoglobulin administration within 3 months before and after vaccination met the primary inclusion criteria. Additionally, immunological response to a pneumococcal conjugate vaccine was analyzed in a subgroup of 67 patients. Patients’ characteristics at the time of first vaccination were recorded. Responses were measured as vaccine-specific antibody titers. Regarding DTaP-Hib-IPV vaccination, 89.3% (n = 75) of all patients achieved protective titers to at least 3 of the 4 vaccine components and were thus considered responders. 10.7% (n = 9) of the patients were classified as non-responders with positive immune response to less than 3 components. Highest response was observed for Hib (97.4%), tetanus (95.2%) and pneumococcal vaccination (83.6%) while only 68.3% responded to vaccination against Bordetella pertussis. Significant risk factors for failure of vaccination response included low B cell counts (p < 0.001; cut-off: 0.05 B cells/nl) and low IgG levels (p = 0.026; mean IgG of responders 816 mg/dl vs. 475 mg/dl of non-responders). Further, a trend was observed that prior cGvHD impairs vaccination response as 88.9% of the non-responders but only 54.7% of the responders had prior cGvHD (p = 0.073). The results demonstrate, that the currently proposed vaccination strategy leads to seroprotection in the majority of alloHSCT patients. 相似文献
80.