首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2124篇
  免费   164篇
  国内免费   24篇
耳鼻咽喉   30篇
儿科学   45篇
妇产科学   6篇
基础医学   258篇
口腔科学   53篇
临床医学   169篇
内科学   511篇
皮肤病学   68篇
神经病学   253篇
特种医学   102篇
外科学   402篇
综合类   12篇
预防医学   46篇
眼科学   26篇
药学   114篇
中国医学   1篇
肿瘤学   216篇
  2023年   52篇
  2022年   89篇
  2021年   144篇
  2020年   61篇
  2019年   103篇
  2018年   90篇
  2017年   80篇
  2016年   81篇
  2015年   113篇
  2014年   123篇
  2013年   111篇
  2012年   170篇
  2011年   169篇
  2010年   104篇
  2009年   84篇
  2008年   120篇
  2007年   115篇
  2006年   95篇
  2005年   78篇
  2004年   73篇
  2003年   78篇
  2002年   62篇
  2001年   7篇
  2000年   7篇
  1999年   8篇
  1998年   14篇
  1997年   8篇
  1996年   8篇
  1995年   5篇
  1994年   4篇
  1993年   6篇
  1992年   8篇
  1991年   4篇
  1990年   4篇
  1989年   4篇
  1987年   8篇
  1986年   2篇
  1985年   1篇
  1983年   2篇
  1982年   4篇
  1981年   2篇
  1980年   1篇
  1979年   1篇
  1977年   1篇
  1975年   1篇
  1974年   1篇
  1973年   1篇
  1967年   1篇
  1965年   1篇
  1963年   1篇
排序方式: 共有2312条查询结果,搜索用时 15 毫秒
61.
Noonan syndrome (NS) is an autosomal dominant disorder characterized by facial anomalies, short stature, chest deformity, congenital heart diseases, and other comorbidities. The challenges faced during anesthetic management of patients with NS could be due to congenital heart diseases, hemostatic disorders, and airway anomalies. Here we describe dental treatment under general anesthesia performed for a 28-year-old man with NS. He had characteristic features of NS along with mild pulmonary valve stenosis. Dental treatment under general anesthesia was performed successfully on 13 occasions with nasotracheal intubation under curve-tipped suction catheter guidance or insertion of a reinforced laryngeal mask airway. This case suggests that for patients with NS, who might present several challenges, dental anesthesiologists should consider the extent of the patient''s disorders to enable them to perform dental treatment safely under general anesthesia.Key Words: Repeated general anesthesia, Noonan syndromeNoonan syndrome (NS) is an autosomal dominant disorder and was first reported by Noonan and Ehmke.1 The primary features of this multisystem disorder include hypertelorism, low-set ears, down-slanting eyes, a webbed neck, congenital heart diseases, short stature, chest deformity, and intellectual impairment.2,3 NS affects males and females equally and has an estimated incidence of 1 in 1000 to 1 in 2500 live births.2,4The challenges faced during anesthetic management of patients with NS could be due to congenital heart diseases, hemostatic disorders, and airway anomalies.58 The present report describes repeated administration of general anesthesia performed by adopting nasotracheal intubation or reinforced laryngeal mask airway insertion for a patient with NS at the time of dental treatment in our hospital.  相似文献   
62.
63.
Legg‐Calvé‐Perthes disease (LCPD) is a childhood hip disorder of ischemic osteonecrosis of the femoral head. Hip joint synovitis is a common feature of LCPD, but the nature and pathophysiology of the synovitis remain unknown. The purpose of this study was to determine the chronicity of the synovitis and the inflammatory cytokines present in the synovial fluid at an active stage of LCPD. Serial MRI was performed on 28 patients. T2‐weighted and gadolinium‐enhanced MR images were used to assess synovial effusion and synovial enhancement (hyperemia) over time. A multiple‐cytokine assay was used to determine the levels of 27 inflammatory cytokines and related factors present in the synovial fluid from 13 patients. MRI analysis showed fold increases of 5.0 ± 3.3 and 3.1 ± 2.1 in the synovial fluid volume in the affected hip compared to the unaffected hip at the initial and the last follow‐up MRI, respectively. The mean duration between the initial and the last MRI was 17.7 ± 8.3 months. The volume of enhanced synovium on the contrast MRI was increased 16.5 ± 8.5 fold and 6.3 ± 5.6 fold in the affected hip compared to the unaffected hip at the initial MRI and the last follow‐up MRI, respectively. In the synovial fluid of the affected hips, IL‐6 protein levels were significantly increased (LCPD: 509 ± 519 pg/mL, non‐LCPD: 19 ± 22 pg/mL; p = 0.0005) on the multi‐cytokine assay. Interestingly, IL‐1β and TNF‐α levels were not elevated. In the active stage of LCPD, chronic hip synovitis and significant elevation of IL‐6 are produced in the synovial fluid. Further studies are warranted to investigate the role of IL‐6 on the pathophysiology of synovitis in LCPD and how it affects bone healing. © 2015 American Society for Bone and Mineral Research  相似文献   
64.
65.
66.
67.
BACKGROUND & AIMS: Percutaneous radiofrequency ablation is a recently introduced treatment for hepatocellular carcinoma, whereas ethanol injection is now a standard therapy. We compared their long-term outcomes. METHODS: Two hundred thirty-two patients with hepatocellular carcinoma who had 3 or fewer lesions, each 3 cm or less in diameter, and liver function of Child-Pugh class A or B were entered onto a randomized controlled trial. The primary end point was survival, and the secondary end points were overall recurrence and local tumor progression. RESULTS: One hundred eighteen patients were assigned to radiofrequency ablation and 114 to ethanol injection. The number of treatment sessions was smaller (2.1 times vs 6.4 times, respectively, P < .0001) and the length of hospitalization was shorter (10.8 days vs 26.1 days, respectively, P < .0001) in radiofrequency ablation than in ethanol injection. Four-year survival rate was 74% (95% CI: 65%-84%) in radiofrequency ablation and 57% (95% CI: 45%-71%) in ethanol injection. Radiofrequency ablation had a 46% smaller risk of death (adjusted relative risk, 0.54 [95% CI: 0.33-0.89], P = .02), a 43% smaller risk of overall recurrence (adjusted relative risk 0.57 [95% CI: 0.41-0.80], P = .0009), and an 88% smaller risk of local tumor progression (relative risk, 0.12 [95% CI: 0.03-0.55], P = .006) than ethanol injection. The incidence of adverse events was not different between the 2 therapies. CONCLUSIONS: Judging from higher survival but similar adverse events, radiofrequency ablation is superior to ethanol injection for small hepatocellular carcinoma.  相似文献   
68.
Surfaces of ice are covered with thin liquid water layers, called quasi-liquid layers (QLLs), even below their melting point (0 °C), which govern a wide variety of phenomena in nature. We recently found that two types of QLL phases appear that exhibit different morphologies (droplets and thin layers) [Sazaki G. et al. (2012) Proc Natl Acad Sci USA 109(4):1052−1055]. However, revealing the thermodynamic stabilities of QLLs remains a longstanding elusive problem. Here we show that both types of QLLs are metastable phases that appear only if the water vapor pressure is higher than a certain critical supersaturation. We directly visualized the QLLs on ice crystal surfaces by advanced optical microscopy, which can detect 0.37-nm-thick elementary steps on ice crystal surfaces. At a certain fixed temperature, as the water vapor pressure decreased, thin-layer QLLs first disappeared, and then droplet QLLs vanished next, although elementary steps of ice crystals were still growing. These results clearly demonstrate that both types of QLLs are kinetically formed, not by the melting of ice surfaces, but by the deposition of supersaturated water vapor on ice surfaces. To our knowledge, this is the first experimental evidence that supersaturation of water vapor plays a crucially important role in the formation of QLLs.Ice is one of the most abundant materials on Earth, and its surfaces are covered with thin liquid water layers even below their melting point (0 °C) (14). Such thin liquid water layers are called “quasi-liquid layers” (QLLs). Because QLLs govern the surface properties of ice just below the melting point, it is well acknowledged that surface melting of ice governs a wide variety of phenomena, such as electrification of thunderclouds (4, 5), regelation (4, 6), frost heave (4, 7), conservation of foods, ice skating (1, 8), preparation of a snowman (1), and growth of ice crystals (2, 4). Therefore, it is essential to understand the surface melting of ice crystals at the molecular level.After Michael Faraday proposed the existence of QLLs in 1842 (1), many studies experimentally confirmed the formation of QLLs by various methods (
Measurement methodReferenceFirst author (experimental condition)
Proton channeling(24, 25)G (S)
Proton backscattering(26, 27)F (U)
Ellipsometry(23, 28)F (U), B (E)
X-ray diffraction(29)K (E)
Glancing-angle X-ray scattering(30, 31)D (U)
Quasi-elastic neutron scattering(32)M (E)
Photoelectron spectroscopy(33, 34)N (E), B (E)
NMR(35, 36)K (E), M (U)
Optical microscopy(37, 38)E (S), G (S)
Optical displacement sensor(39)K (U)
Infrared spectroscopy(40)S (S)
Sum-frequency vibrational spectroscopy(41, 42)W (E)
Atomic force microscopy(4346)B (S), D (U), S (U, E, S), P (E)
Open in a separate windowAll these studies showed a significant increase in the thickness of QLLs with increasing temperature, although such increase showed considerable variation depending on the measurement methods and researchers; there also exist many studies on QLLs by molecular dynamics and theoretical calculations, although such studies are not listed here; first author presents a first character of first author''s family name; in experimental condition, S, E, and U show supersaturated, equilibrium, and undersaturated conditions for ice crystals, respectively.Recently, we and Olympus Engineering Co., Ltd., have developed one such technique, namely, laser confocal microscopy combined with differential interference contrast microscopy (LCM-DIM) (9), which can directly visualize the 0.37-nm-thick elementary steps on ice crystal surfaces (10, 11). We found that two types of QLL phases with different morphologies appear (1214): Round liquid-like drops (α-QLLs) and thin liquid-like layers (β-QLLs) emerge, irrespective of the face indices of the ice surfaces. Until our recent studies were reported, it had been believed for many years that only one QLL phase appears in the conventional picture of surface melting (24). Hence, our results demonstrate that the conventional picture needs significant reexamination.However, it is still unclear how we can explain the generation of the two types of QLL phases. To approach this issue, we first focused our attention on the thermodynamic stabilities of the two types of QLLs. In this study, we examined a water vapor pressure range in which the two types of QLL phases appeared on ice basal faces when examined by LCM-DIM. As a result, we found that the two types of QLL phases are metastable phases that appear only when the water vapor pressure is higher than a certain critical supersaturation.  相似文献   
69.
Accurate and Easy Measurement of Sliding Distance of Intramedullary Nail in Trochanteric Fracture     
Nobuaki Chinzei  Takafumi Hiranaka  Takahiro Niikura  Takaaki Fujishiro  Shinya Hayashi  Noriyuki Kanzaki  Shingo Hashimoto  Yoshitada Sakai  Ryosuke Kuroda  Masahiro Kurosaka 《Clinics in Orthopedic Surgery》2015,7(2):152-157

Background

In daily clinical practice, it is essential to properly evaluate the postoperative sliding distance of various femoral head fixation devices (HFD) for trochanteric fractures. Although it is necessary to develop an accurate and reproducible method that is unaffected by inconsistent postoperative limb position on radiography, few studies have examined which method is optimal. Therefore, the purpose of this study is to prospectively compare the accuracy and reproducibility of our four original methods in the measurement of sliding distance of the HFD.

Methods

Radiographs of plastic simulated bone implanted with Japanese proximal femoral nail antirotation were taken in five limb postures: neutral, flexion, minute internal rotation, greater external rotation, and flexion with external rotation. Orthopedic surgeons performed five measurements of the sliding distance of the HFD in each of the flowing four methods: nail axis reference (NAR), modified NAR, inner edge reference, and nail tip reference. We also assessed two clinical cases by using these methods and evaluated the intraclass correlation coefficients.

Results

The measured values were consistent in the NAR method regardless of limb posture, with an even smaller error when using the modified NAR method. The standard deviation (SD) was high in the nail tip reference method and extremely low in the modified NAR method. In the two clinical cases, the SD was the lowest in the modified NAR method, similar to the results using plastic simulated bone. The intraclass correlation coefficients showed the highest value in the modified NAR method.

Conclusions

We conclude that the modified NAR method should be the most recommended based on its accuracy, reproducibility, and usefulness.  相似文献   
70.
Comparison of the Sliding and Femoral Head Rotation among Three Different Femoral Head Fixation Devices for Trochanteric Fractures     
Nobuaki Chinzei  Takafumi Hiranaka  Takahiro Niikura  Mitsuo Tsuji  Ryosuke Kuroda  Minoru Doita  Masahiro Kurosaka 《Clinics in Orthopedic Surgery》2015,7(3):291-297

Background

Recently, various femoral head fixation devices (HFDs) for trochanteric fractures have become available. However, there are some cases in which femoral head rotation with excessive sliding of the HFD is observed and it is often followed by cutout. The purpose of this study is to compare the ability of the three types of HFDs to prevent femoral head rotation.

Methods

Between July 2005 and December 2009, 206 patients aged over 60 years with trochanteric fractures who had undergone surgical treatment using a short femoral nail in our institution were enrolled into the study. We used the gamma 3 nail (GMN) as the screw-type HFD in 66 cases, the gliding nail (GLN) as a non-cylindrical blade in 76 cases, and the proximal femoral nail antirotation (PFNA) as a cylindrical blade in 64 cases. The sliding length of HFDs and the occurrence of femoral head rotation were evaluated by assessing radiographs as the main outcome, and the results were compared among these devices.

Results

A comparison of the degree of sliding in the GMN group showed that femoral head rotation was observed significantly more frequently in cases with rotation. Further, it appeared that femoral head rotation occurred more frequently in comminuted fractures. However, no significant differences between the sliding lengths of the different HFDs were observed among three groups. Femoral head rotation was observed in 15 cases of GMN (22.7%), 0 case of GLN, and 5 case of PFNA (7.8%). Significant differences with regard to the occurrence of femoral head rotation were observed among the three groups. Furthermore, significant differences were also observed between GLN and PFNA with respect to the occurrence of femoral head rotation.

Conclusions

The ability to stabilize femoral head appears to be greater with blade-type materials than with screw-type materials. Furthermore, we believe that a non-cylindrical blade is preferable to a cylindrical blade for the surgical treatment of comminuted, unstable trochanteric fractures in order to prevent femoral head rotation and cut-out.  相似文献   
[首页] « 上一页 [2] [3] [4] [5] [6] 7 [8] [9] [10] [11] [12] 下一页 » 末  页»
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号