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   3842篇
  免费   194篇
  国内免费   32篇
耳鼻咽喉   15篇
儿科学   105篇
妇产科学   30篇
基础医学   443篇
口腔科学   77篇
临床医学   314篇
内科学   1057篇
皮肤病学   56篇
神经病学   257篇
特种医学   113篇
外科学   810篇
综合类   23篇
预防医学   78篇
眼科学   14篇
药学   272篇
中国医学   30篇
肿瘤学   374篇
  2023年   25篇
  2022年   46篇
  2021年   94篇
  2020年   67篇
  2019年   72篇
  2018年   88篇
  2017年   67篇
  2016年   62篇
  2015年   72篇
  2014年   107篇
  2013年   122篇
  2012年   223篇
  2011年   227篇
  2010年   108篇
  2009年   96篇
  2008年   208篇
  2007年   184篇
  2006年   191篇
  2005年   230篇
  2004年   208篇
  2003年   179篇
  2002年   185篇
  2001年   72篇
  2000年   88篇
  1999年   85篇
  1998年   67篇
  1997年   51篇
  1996年   41篇
  1995年   43篇
  1994年   35篇
  1993年   35篇
  1992年   62篇
  1991年   59篇
  1990年   61篇
  1989年   54篇
  1988年   45篇
  1987年   48篇
  1986年   37篇
  1985年   42篇
  1984年   32篇
  1983年   32篇
  1982年   17篇
  1981年   12篇
  1979年   19篇
  1978年   20篇
  1977年   19篇
  1974年   14篇
  1973年   13篇
  1971年   16篇
  1970年   19篇
排序方式: 共有4068条查询结果,搜索用时 15 毫秒
991.
 We present a case of cardiac sarcoidosis with advanced atrioventricular (AV) block in a 45-year-old female patient. Although endomyocardial biopsy and other diagnostic findings were inconclusive, gastrocnemial muscle biopsy indicated a definitive diagnosis of sarcoidosis. Whole-body gallium-67 scintigraphy was useful to confirm the suspicion of the presence of sarcoidosis. Thereafter, magnetic resonance imaging (MRI) was successful in detecting the space-occupying lesion in the skeletal muscle, leading to a positive diagnosis of sarcoidosis. It is concluded that the presence of myocardial disease, such as cardiac sarcoidosis, should be considered when advanced AV block is encountered. Even if endomyocardial biopsy and other conventional diagnostic approaches are inconclusive, the possibility of cardiac involvement in sarcoidosis cannot be denied. This case report stresses the importance of more advanced diagnostic approaches, such as whole-body gallium scanning and MRI, in clarifying the etiology of AV block. Establishing the diagnosis of cardiac sarcoidosis is important in determining whether or not to begin effective long-term treatment with corticosteroids. Received: February 2, 2002 / Accepted: October 12, 2002 Correspondence to M. Sekiguchi  相似文献   
992.
The purpose of this study was to investigate the clinical significance of the reverse redistribution (RR) phenomenon on technetium-99m ((99m)Tc)-tetrofosmin myocardial single photon emission computed tomography (SPECT) performed at rest. Twenty-five patients underwent myocardial SPECT 3 weeks after the onset of acute myocardial infarction. Myocardial images were acquired at 40 min (early) and 4 h (delayed) after the injection of 740 MBq of (99m)Tc-tetrofosmin. The regional myocardial uptake of the tracer in 26 segments of the left ventricular (LV) wall was visually scored from 0 (no activity) to 3 (normal activity), and then the RR was defined as a decrease of more than 1 point in the activity score on the delayed image compared with that on the early image. Regions with an activity score of 3 on both the early and delayed images were defined as normal, and those with a score of 0 or 1 on the early image were considered to have a fixed defect. The regional myocardial (99m)Tc-tetrofosmin uptake and washout rate were also quantitatively assessed in each region. In addition, exercise stress electrocardiograph-gated SPECT with (99m)Tc-tetrofosmin was performed within 1 week of the rest study, and the percent count increase (%CI) during myocardial contraction in each corresponding region was studied. RR was observed in 18 of the 25 patients. The regional washout rate of (99m)Tc-tetrofosmin was significantly higher in the RR regions (45.0+/-3.8%) than in either the normal regions (36.4+/-4.1%, p<0.001) or in those with a fixed defect (39.7+/-3.9%, p<0.001). The %CI in the RR regions (10.4+/-10.4%) was significantly less than that in the normal regions (23.5+/-10.1%, p<0.001); however, no significant difference was found between the RR regions and those with a fixed defect (8.0+/-7.2%). In patients with acute myocardial infarction, the regions showing the RR phenomenon on (99m)Tc-tetrofosmin SPECT have severely impaired LV wall contraction after exercise.  相似文献   
993.
994.
Cardiopulmonary late toxicity is of concern in concurrent chemoradiotherapy (CCRT) for esophageal cancer. The aim of this study was to examine the benefit of proton beam therapy (PBT) using clinical data and adaptive dose–volume histogram (DVH) analysis. The subjects were 44 patients with esophageal cancer who underwent definitive CCRT using X-rays (n = 19) or protons (n = 25). Experimental recalculation using protons was performed for the patient actually treated with X-rays, and vice versa. Target coverage and dose constraints of normal tissues were conserved. Lung V5–V20, mean lung dose (MLD), and heart V30–V50 were compared for risk organ doses between experimental plans and actual treatment plans. Potential toxicity was estimated using protons in patients actually treated with X-rays, and vice versa. Pulmonary events of Grade ≥2 occurred in 8/44 cases (18%), and cardiac events were seen in 11 cases (25%). Risk organ doses in patients with events of Grade ≥2 were significantly higher than for those with events of Grade ≤1. Risk organ doses were lower in proton plans compared with X-ray plans. All patients suffering toxicity who were treated with X-rays (n = 13) had reduced predicted doses in lung and heart using protons, while doses in all patients treated with protons (n = 24) with toxicity of Grade ≤1 had worsened predicted toxicity with X-rays. Analysis of normal tissue complication probability showed a potential reduction in toxicity by using proton beams. Irradiation dose, volume and adverse effects on the heart and lung can be reduced using protons. Thus, PBT is a promising treatment modality for the management of esophageal cancer.  相似文献   
995.
This multicenter prospective study ( Japanese Radiation Oncology Study Group: JROSG 05-5) aimed to evaluate the effectiveness of postoperative radiotherapy (PORT) in patients with ductal carcinoma in situ (DCIS) with an involved surgical margin or close margin widths of ≤1 mm or less. PORT consisted of whole-breast irradiation (50 Gy in 25 fractions) followed by boost irradiation (10 Gy in 5 fractions). Eligibility criteria were as follows: (i) DCIS without an invasive carcinoma component, (ii) age between 20 and 80 years old, (iii) involved margin or close margin widths of ≤1 mm, (iv) refusal of re-resection, (v) performance status of 0–2, and (vi) written informed consent. The primary endpoint was ipsilateral breast tumor recurrence (IBTR), and secondary endpoints were overall survival (OS), relapse-free survival (RFS), recurrence patterns, and adverse events. A total of 37 patients from 12 institutions were enrolled from January 2007 to May 2009. The median follow-up time was 62 months (range, 28–85 months). The median pathological tumor size was 2.5 cm (range, 0.3–8.5 cm). Of the 37 patients, 21 had involved margins, and 16 had close margins. The 5-year IBTR, OS and RFS rates were 6% (95% confidence interval [CI]: 2–21), 97% (95% CI: 83–99) and 91% (95% CI: 77–97), respectively. Two patients developed local recurrence at the original site after 39 and 58 months. No severe adverse events were found. Our study suggests that this PORT regimen could be a treatment option for patients with DCIS with involved margin or close margin who don''t desire re-resection.  相似文献   
996.

Background

Soccer is a high-intensity sport with a high injury rate. Among youth soccer players, lower extremity pain is a major problem that could be associated with trunk function. This study investigated the association between lower extremity pain and trunk pain among youth soccer players.

Methods

A cross-sectional study involving youth soccer players participating in the Miyagi Amateur Sports Association was conducted using a self-reported questionnaire. A multiple logistic regression analysis was used to examine the association between trunk pain and lower extremity pain. Covariates were sex, age, body mass index, height increase, number of days of training per week, practice time per day on weekdays or weekends, competition levels, frequency of participation in games, and previous injuries.

Results

The final study population comprised 1139 youth soccer players (age, 6–15 years; male, 94.2%). Lower extremity pain with concomitant trunk pain occurred in 61.8% (42/68). Trunk pain was significantly associated with lower extremity pain (adjusted odds ratio [OR], 6.82; 95% confidence interval [CI], 3.99–11.67). Back pain and hip pain were significantly associated with knee pain (adjusted OR [95% CI]: 7.63 [3.70–15.76] and 3.84 [1.89–7.83], respectively), ankle pain (adjusted OR [95% CI]: 9.03 [4.42–18.44] and 5.43 [2.77–10.62], respectively), and both knee and ankle pain (adjusted OR [95% CI]: 13.67 [6.01–31.09] and 5.98 [2.56–13.97], respectively).

Conclusions

Trunk pain was associated with lower extremity pain among youth soccer players. Clinicians and coaches should consider comorbidities while treating those players.
  相似文献   
997.
Background: Studies on patients with hepatitis C virus (HCV) of genotype 1b have suggested that amino acids (aa) 70 and/or 91 of the HCV core protein affect the outcome of interferon (IFN)‐α and ribavirin (RBV) therapy, although there are no clear supporting data in vitro. Aims: This study was designed to determine the differences among the antiviral activities of HCV core proteins with various substitutions at aa70 and/or aa91. Methods: The retroviral vectors expressing the HCV core proteins with substitutions of arginine/leucine, arginine/methionine, glutamine/leucine or glutamine/methionine at aa70/aa91 were transiently transfected or stably transducted into an immortalized hepatocyte line (PH5CH8), hepatoma cell lines and an HCV‐RNA replicating cell line (sOR) to evaluate antiviral responses to IFN‐α or IFN‐α/RBV. Sequence analysis was performed using genome‐length HCV‐RNA replicating cells (OR6 and AH1) to evaluate HCV core mutations during IFN‐α treatment. Results: The promoter activity levels of IFN‐stimulated genes in the transiently transfected cells or the mRNA levels of 2′‐5′‐oligoadenylate synthetase in the stably transducted PH5CH8 cells were not associated with the HCV core aa70 and/or aa91 substitutions during IFN‐α treatment. Antiviral responses to IFN‐α or IFN‐α/RBV treatment were enhanced in sOR cells stably transducted with the HCV core, although there were no differences in antiviral responses among the cells expressing different core types. Sequence analysis showed no aa mutations after IFN‐α treatment. Conclusions: Antiviral activities were enhanced by HCV core transduction, but they were not associated with the HCV core aa70 and/or aa91 substitutions by in vitro analysis.  相似文献   
998.
Performing angiography in the prone position is a difficult technique; however it is useful in some emergency situation. We experienced a 60 years old male who was performed lipema excision on his back in his family doctor's clinic. Since massive arterial bleeding could not be controlled with manual astriction, he transferred to our hospital in prone position with hemodynamic instability. Operating field was not kept because of massive bleeding; therefore surgical treatment was impossible. We planed emergency arterial embolization (AE) in prone position. Hence we chose the left radial artery for vascular access. The left subclavicle arteriography showed many major and minor feeding arteries from left subclavicular and axillary arteries and a massive extravasation of the contrast medium. Three major feeding arteries were performed AE with gelatin sponge and steel coils, After AE, massive bleeding was controlled. He could discharge from our hospital on the 5th hospital day without any complication. Arterial embolization for lifethreatening bleeding from subcutaneous hypervascular tumor in the prone position is first report to our knowledge, and it is extremely rare. However we thought that this technique is useful for patients who could not turn in the supine position, e.g. massive bleeding during renal biopsy and penetrating trauma from back.  相似文献   
999.
1000.
The kidney develops through reciprocal interactions between two precursor tissues: the metanephric mesenchyme and the ureteric bud. We previously demonstrated that the zinc finger protein Sall1 is essential for ureteric bud attraction toward the mesenchyme. Here, we show that Kif26b, a kinesin family gene, is a downstream target of Sall1 and that disruption of this gene causes kidney agenesis because of impaired ureteric bud attraction. In the Kif26b-null metanephros, compact adhesion between mesenchymal cells adjacent to the ureteric buds and the polarized distribution of integrin α8 were impaired, resulting in failed maintenance of Gdnf, a critical ureteric bud attractant. Overexpression of Kif26b in vitro caused increased cell adhesion through interactions with nonmuscle myosin. Thus, Kif26b is essential for kidney development because it regulates the adhesion of mesenchymal cells in contact with ureteric buds.  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