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   3270篇
  免费   214篇
  国内免费   33篇
耳鼻咽喉   20篇
儿科学   100篇
妇产科学   41篇
基础医学   365篇
口腔科学   32篇
临床医学   207篇
内科学   1142篇
皮肤病学   65篇
神经病学   125篇
特种医学   74篇
外科学   592篇
综合类   14篇
预防医学   89篇
眼科学   28篇
药学   220篇
中国医学   2篇
肿瘤学   401篇
  2024年   5篇
  2023年   50篇
  2022年   63篇
  2021年   129篇
  2020年   59篇
  2019年   81篇
  2018年   114篇
  2017年   94篇
  2016年   102篇
  2015年   127篇
  2014年   143篇
  2013年   163篇
  2012年   267篇
  2011年   288篇
  2010年   156篇
  2009年   150篇
  2008年   213篇
  2007年   200篇
  2006年   175篇
  2005年   192篇
  2004年   166篇
  2003年   146篇
  2002年   132篇
  2001年   27篇
  2000年   15篇
  1999年   23篇
  1998年   29篇
  1997年   21篇
  1996年   20篇
  1995年   21篇
  1994年   24篇
  1993年   13篇
  1992年   10篇
  1991年   13篇
  1990年   9篇
  1989年   6篇
  1988年   7篇
  1987年   7篇
  1986年   5篇
  1985年   5篇
  1984年   10篇
  1982年   3篇
  1981年   6篇
  1980年   3篇
  1978年   6篇
  1977年   7篇
  1973年   2篇
  1969年   2篇
  1968年   2篇
  1962年   1篇
排序方式: 共有3517条查询结果,搜索用时 0 毫秒
41.
A 66-year-old woman admitted with dyspnea on exertion had atrial fibrillation and left ventricular dysfunction. Echocardiography revealed an atrial septal defect (ASD) and a soft, easily deformable thrombus in the dilated left atrium. The atrial mass suddenly disappeared on the 10th day after admission, and contrast-enhanced chest computed tomography and pulmonary blood flow scintigraphy showed that the thrombus had detached from the left atrium, floated into the right atrium through the ASD and caused pulmonary embolism. This is the first documented case of a left atrial thrombus causing pulmonary embolism by passing through an ASD. When an ASD is present, it is important to consider not only paradoxical thromboembolism (from the right to the left atrium), but also pulmonary embolism caused by thromboembolism from the left to the right atrium.  相似文献   
42.
BackgroundRadial artery access has been shown to reduce mortality and bleeding events, especially in patients with acute coronary syndromes. Despite this, interventional cardiologists experienced in femoral artery access still prefer that route for percutaneous coronary intervention. Little is known regarding the merits of each vascular access in patients stratified by their risk of bleeding.MethodsPatients from the Global Leaders trial were dichotomized into low or high risk of bleeding by the median of the PRECISE-DAPT score. Clinical outcomes were compared at 30 days.ResultsIn the overall population, there were no statistical differences between radial and femoral access in the rate of the primary end point, a composite of all-cause mortality, or new Q-wave myocardial infarction (MI) (hazard ratio [HR] 0.70, 95% confidence interval [CI] 0.42-1.15). Radial access was associated with a significantly lower rate of the secondary safety end point, Bleeding Academic Research Consortium (BARC) 3 or 5 bleeding (HR 0.55, 95% CI 0.36-0.84). Compared by bleeding risk strata, in the high bleeding score population, the primary (HR 0.47, 95% CI 0.26-0.85; P = 0.012; Pinteraction = 0.019) and secondary safety (HR 0.57, 95% CI 0.35-0.95; P = 0.030; Pinteraction = 0.631) end points favoured radial access. In the low bleeding score population, however, the differences in the primary and secondary safety end points between radial and femoral artery access were no longer statistically significant.ConclusionsOur findings suggest that the outcomes of mortality or new Q-wave MI and BARC 3 or 5 bleeding favour radial access in patients with a high, but not those with a low, risk of bleeding. Because this was not a primary analysis, it should be considered hypothesis generating.  相似文献   
43.
Epstein-Barr virus (EBV)-associated gastric cancer (EBVaGC) cells originate from a single-cell clone infected with EBV. However, more than 95% of patients with gastric cancer have a history of Helicobacter pylori (H. pylori) infection, and H. pylori is a major causative agent of gastric cancer. Therefore, it has long been argued that H. pylori infection may affect the development of EBVaGC, a subtype of gastric cancer. Atrophic gastrointestinal inflammation, a symptom of H. pylori infection, is observed in the gastric mucosa of EBVaGC. Therefore, it remains unclear whether H. pylori infection is a cofactor for gastric carcinogenesis caused by EBV infection or whether H. pylori and EBV infections act independently on gastric cancer formation. It has been reported that EBV infection assists in the onco-genesis of gastric cancer caused by H. pylori infection. In contrast, several studies have reported that H. pylori infection accelerates tumorigenesis initiated by EBV infection. By reviewing both clinical epidemiological and experimental data, we reorganized the role of H. pylori and EBV infections in gastric cancer formation.  相似文献   
44.
Herein, we report the successful performance of a laparoscopy-assisted spleen-preserving distal pancreatectomy with conservation of the splenic artery and vein for a patient with pancreatic cystadenoma, as a minimally invasive procedure with the preservation of function. The laparoscopy-assisted distal pancreatectomy procedure involved detaching the spleen and the distal pancreas from the retroperitoneum by a hand-assisted procedure, removing them from the peritoneal cavity through a small incision, and detaching the distal pancreas by ligating and transecting the short gastric artery and vein and the branches of the splenic artery and vein, while the spleen and main splenic artery and vein were preserved under direct view. The pancreatic parenchyma was transected with a stapling device (TL-30), and continuous suturing was added to the resected margin. The patient’s postoperative course was uneventful; the patient started to eat and walk on postoperative day 2 and was discharged on day 8. It is considered that the combination of hand-assisted and laparoscopy-assisted distal pancreatectomy, with conservation of the splenic artery and vein, is a minimally invasive and clinically useful technique for treating tumors of cystic disease of the pancreas with low-grade malignant potential, or benign solitary neuroendocrine tumors.  相似文献   
45.

Background

The Ras-like GTPases, RalA and RalB are members of the Ras superfamily of small GTPases. Aberrant activation of Ral is a major cause of human tumorigenesis induced by oncogenic Ras. Serum anti-RalA antibodies are induced in esophageal carcinoma patients. However, detailed comparisons of their pathological characteristics are unavailable, and conventional serum markers have not been well evaluated.

Methods

Serum samples of 171 patients with esophageal squamous cell carcinoma and 73 healthy individuals were analyzed using specifically developed ELISA system for serum anti-RalA antibodies. A cut-off optical density value was fixed at 0.255 (the control mean + 2 SD). Clinicopathological characteristics and positive rates of conventional tumor markers were evaluated for seropositive patients.

Results

Overall positive rate for serum anti-RalA antibodies was 18 %, which gradually increased with the tumor stages. Although the positive rate for serum anti-RalA antibodies was comparable with that of carcinoembryonic antigen (24 %) and CYFRA21-1 (21 %), it was lower than the rate for serum p53 antibodies (31 %) and squamous cell carcinoma antigen (37 %). Although serum anti-RalA antibodies were not associated with other serum markers, it was inversely associated with serum p53 antibodies. No clear association was observed between serum anti-RalA antibodies and RalA immunoreactivity.

Conclusions

Presence of serum anti-RalA antibodies is associated with tumor stages, but not with conventional tumor markers. Serum anti-RalA antibodies may be candidate serum markers in combination with other serum markers for esophageal squamous cell carcinoma.
  相似文献   
46.
Enteroscopy   总被引:4,自引:0,他引:4  
Wireless capsule endoscopy and double-balloon endoscopy are new methods of enteroscopy that have been introduced in recent years. Wireless capsule endoscopy is an epoch-making examination method that makes possible an endoscopic imaging examination of the entire small intestine without discomfort and without confining patients to a medical facility. Although it is expected to be useful as an initial examination for finding diseases of the small intestine, it cannot be used for biopsy or treatment. One risk associated with the capsule endoscopy technique is entrapment by strictures. Double-balloon endoscopy is based on a new insertion technique in which two balloons, one at the distal end of the endoscope and the other at the distal end of an overtube, are operated in combination, and the endoscope is inserted while simultaneously shortening the intestine. It can be inserted through either the mouth or the anus, allowing the observation of the entire gastrointestinal tract. It features excellent maneuverability even in the distal small intestine, and enables back-and-forth observation, biopsy, and endoscopic treatment at any given site. These two new enteroscopy techniques are expected to lead to innovations in how diseases of the small intestine are approached.  相似文献   
47.
We report an autopsy case of acute pancreatitis with a high serum IgG4 concentration complicated by systemic amyloid A amyloidosis and rheumatoid arthritis (RA). The patient was a 42-year-old Japanese female with a 22-year history of rheumatoid arthritis. She was diagnosed with myasthenia gravis when she was 31-year old. At the onset of pancreatitis, the patient was anti-nudear antibody-positive, and had high serum gamma globulin and IgG4 levels. Dexamethasone and conventional therapy induced clinical remission and significantly decreased the serum IgG4 and gamma globulin. However, despite the decreased disease parameters, the patient developed a bleeding pseudocyst and died of cardiac failure. In the autopsy examination, it was determined that pancreatitis was probably caused by ischemia due to vascular obstruction caused by amyloid deposition in the pancreas. Even though acute pancreatitis is a rare complication in RA patients, we speculate that an autoimmune pancreatitis-related mechanism and ischemia due to vascular obstruction by amyloid deposition might be attributable to a single source that leads to acute pancreatitis in our particular case.  相似文献   
48.
49.
Purpose:We aimed to investigate the performance of high resolution-diffusion-weighted imaging (HR-DWI) using readout-segmented echo-planar imaging in visualizing malignant breast lesions and evaluating their extent, using pathology as a reference.Methods:This retrospective study included patients who underwent HR-DWI with surgically confirmed malignant breast lesions. Two radiologists blinded to the final diagnosis evaluated HR-DWI independently and identified the lesions, measuring their maximum diameters. Another radiologist confirmed if those lesions were identical to the pathology. The maximum diameters of the lesions between HR-DWI and pathology were compared, and their correlations were calculated using Spearman’s correlation coefficient. Apparent diffusion coefficient (ADC) values of the lesions were measured.Results:Ninety-five mass/64 non-mass lesions were pathologically confirmed in 104 females. Both radiologists detected the same 93 mass lesions (97.9%). Spearman’s correlation coefficient for mass lesions were 0.89 and 0.90 (P < 0.0001 and 0001) for the two radiologists, respectively. The size differences within 10 mm were 90.3% (84/93) and 94.6% (88/93) respectively. One radiologist detected 35 non-mass lesions (54.7%) and another radiologist detected 32 non-mass lesions (50.0%), of which 28 lesions were confirmed as identical. Spearman’s correlation coefficient for non-mass lesions were 0.59 and 0.22 (P = 0.0002 and 0.22), respectively. The mean ADC value of mass lesions and non-mass lesions were 0.80 and 0.89 × 10−3 mm2/s, respectively.Conclusion:Using HR-DWI, malignant mass lesions were depicted with excellent agreement with the pathological evaluation. Approximately half of the non-mass lesions could not be identified, suggesting a current limitation of HR-DWI.  相似文献   
50.
Asymptomatic dural arteriovenous fistulas (DAVFs) with cortical venous reflux (CVR) are now more commonly encountered. However, patients with an incidental onset may have a less aggressive clinical course. It is desirable to explore methods and indicators to predict the clinical outcomes. This study investigates whether the relative signal intensity (rSI) of the draining vessels on the time-of-flight magnetic resonance angiography is related to clinical behavior in patients with intracranial DAVFs. We retrospectively reviewed 36 intracranial DAVFs. The patients were categorized as those with either aggressive-presentation or non-aggressive-presentation (n = 16 and 20, respectively). The rSIs of the shunt points, affected sinuses, and veins with CVR were compared between the two groups. The two groups were not significantly different in terms of rSIs of the shunt points and affected sinuses (p = 0.37 and 0.41, respectively). However, a significant positive correlation was observed in the rSI of the veins with CVR between the aggressive and non-aggressive behavior groups (p < 0.0001). The rSI of the veins with CVR could serve as a reliable indicator of aggressive behavior in intracranial DAVFs, and its optimal cutoff value was 1.63 with high sensitivity and specificity for predicting aggressive behavior (area under the curve, 0.909).  相似文献   
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