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   6010篇
  免费   394篇
  国内免费   126篇
耳鼻咽喉   99篇
儿科学   128篇
妇产科学   64篇
基础医学   934篇
口腔科学   151篇
临床医学   588篇
内科学   1260篇
皮肤病学   130篇
神经病学   464篇
特种医学   485篇
外科学   769篇
综合类   112篇
预防医学   269篇
眼科学   60篇
药学   503篇
中国医学   79篇
肿瘤学   435篇
  2024年   3篇
  2023年   41篇
  2022年   125篇
  2021年   263篇
  2020年   128篇
  2019年   129篇
  2018年   168篇
  2017年   162篇
  2016年   228篇
  2015年   362篇
  2014年   406篇
  2013年   447篇
  2012年   585篇
  2011年   554篇
  2010年   320篇
  2009年   301篇
  2008年   348篇
  2007年   344篇
  2006年   261篇
  2005年   176篇
  2004年   127篇
  2003年   105篇
  2002年   92篇
  2001年   101篇
  2000年   78篇
  1999年   57篇
  1998年   101篇
  1997年   70篇
  1996年   66篇
  1995年   57篇
  1994年   49篇
  1993年   49篇
  1992年   22篇
  1991年   7篇
  1990年   17篇
  1989年   22篇
  1988年   25篇
  1987年   16篇
  1986年   21篇
  1985年   17篇
  1984年   9篇
  1983年   12篇
  1982年   9篇
  1981年   4篇
  1980年   8篇
  1979年   4篇
  1978年   6篇
  1977年   6篇
  1976年   12篇
  1975年   9篇
排序方式: 共有6530条查询结果,搜索用时 15 毫秒
981.

Purpose

Dexamethasone has a high therapeutic index when used to prevent chemotherapy-induced nausea and vomiting. However, the chronic use of glucocorticoids has been associated with suppression of the hypothalamic–pituitary–adrenal axis. Therefore, the authors designed this pilot study to assess the incidence of adrenal insufficiency after dexamethasone therapy as an antiemetic in cancer patients receiving chemotherapy.

Methods

The rapid adrenocorticotropic hormone (ACTH) stimulation test was performed in 103 cancer patients, who had been treated with high-dose dexamethasone as an antiemetic for more than 3 months. When response to the rapid ACTH stimulation test was abnormal, the patient received corticosteroid replacement by prednisolone 7.5 mg daily for 1–2 weeks and after prednisolone replacement, changes in symptoms associated with adrenal insufficiency were investigated using a visual analog scale.

Results

Forty-five of the 103 patients (43.7%) showed a suppressed adrenal response to the rapid ACTH stimulation test, and the incidence of adrenal suppression was found to be significantly affected by megestrol acetate use (P?=?0.035). Thirty-three patients with a suppressed adrenal function achieved an improvement in quality of life after prednisolone replacement, as determined using a self-report questionnaire (22.9?±?14.7 to 14.8?±?11.0, P?<?0.001).

Conclusions

We suggest that suppression of adrenal response is common after antiemetic dexamethasone therapy in cancer patients receiving chemotherapy.  相似文献   
982.
983.
Jeon YJ  Myung SK  Lee EH  Kim Y  Chang YJ  Ju W  Cho HJ  Seo HG  Huh BY 《Nutrition and cancer》2011,63(8):1196-1207
This meta-analysis aimed to investigate the effects of beta-carotene supplements alone on cancer prevention as reported by randomized controlled trials (RCTs). We searched PubMed, EMBASE, and CENTRAL. Among the 848 articles searched, 6 randomized controlled trials, including 40,544 total participants, 20,290 in beta-carotene supplement groups, and 20,254 in placebo groups, were included in the final analysis. In a meta-analysis of 6 RCTs, beta-carotene supplements had no preventive effect on either cancer incidence [relative risk (RR) = 1.08, 95% confidence interval (CI) = 0.99-1.18] or cancer mortality (RR = 1.00, 95% CI = 0.87-1.15). Similar findings were observed in both primary prevention trials and secondary prevention trials. Subgroup analyses by various factors revealed no preventive effect of beta-carotene supplementation on cancer prevention and that it significantly increased the risk of urothelial cancer, especially bladder cancer (RR = 1.52, 95% CI = 1.03-2.24) and marginally increased the risk of cancer among current smokers (RR = 1.07, 95% CI = 0.99-1.17). The current meta-analysis of RCTs indicated that there is no clinical evidence to support the overall primary or secondary preventive effect of beta-carotene supplements on cancer. The potential effects, either beneficial or harmful, of beta-carotene supplementation on cancer should not be overemphasized.  相似文献   
984.
985.
986.

Background

Right ventricular ejection fraction (RV-EF) has traditionally been used to measure and compare RV function serially over time, but may be a relatively insensitive marker of change in RV myocardial contractile function. We developed a cardiovascular magnetic resonance (CMR) tagging-based technique with a view to rapid and reproducible measurement of RV long axis function and applied it in patients with congenital heart disease.

Methods

We studied 84 patients: 56 with repaired Tetralogy of Fallot (rTOF); 28 with atrial septal defect (ASD): 13 with and 15 without pulmonary hypertension (RV pressure > 40 mmHG by echocardiography). For comparison, 20 healthy controls were studied. CMR acquisitions included an anatomically defined four chamber cine followed by a cine gradient echo-planar sequence in the same plane with a labelling pre-pulse giving a tag line across the basal myocardium. RV tag displacement was measured with automated registration and tracking of the tag line together with standard measurement of RV-EF.

Results

Mean RV displacement was higher in the control (26 ± 3 mm) than in rTOF (16 ± 4 mm) and ASD with pulmonary hypertension (18 ± 3 mm) groups, but lower than in the ASD group without (30 ± 4 mm), P < 0.001. The technique was reproducible with inter-study bias ± 95% limits of agreement of 0.7 ± 2.7 mm. While RV-EF was lower in rTOF than in controls (49 ± 9% versus 57 ± 6%, P < 0.001), it did not differ between either ASD group and controls.

Conclusions

Measurements of RV long axis displacement by CMR tagging showed more differences between the groups studied than did RV-EF, and was reproducible, quick and easy to apply. Further work is needed to assess its potential use for the detection of longitudinal changes in RV myocardial function.  相似文献   
987.

Background

Studies regarding the discrimination of non-neoplastic lesion, adenoma, and cancer of the stomach using magnifying endoscopy with flexible spectral imaging color enhancement system (FIME) in each different channel of that system have not yet been reported.

Aims

To ascertain the usefulness of FIME discriminating among the three kinds of gastric lesions.

Methods

When finding a lesion to be a possible neoplasm using conventional endoscopy, the examiner discriminated among the three kinds of gastric lesions by observing the pit pattern on the lesion using magnifying endoscopy with white light (WLME) and then recorded the image. The procedure was repeated three more times with FIME with channel 0, 2, and 4. The four recorded images per lesion were then given to four raters for discriminating among the three kinds of gastric lesions.

Results

The proportion of agreement and the degree of agreement between endoscopic and pathological diagnosis (AEP) by WLME were 0.85 and 0.76, respectively, and those by FIME were 0.91 and 0.86, respectively. All AEPs from discriminations with FIME was higher than that with WLME. AEPs from the discriminations with FIME with channel 4 were higher than those with FIME with channel 0 or 2. The degree of interobserver agreement among the results of the four raters was 0.42 for WLME and 0.50?C0.59 for FIME with each of the three different channels.

Conclusions

FICE is useful in discriminating among non-neoplastic lesions, adenoma, and cancer of the stomach, and channel 4 of the FICE is better than channel 0 and 2 for the discriminations.  相似文献   
988.
989.

Background

Siroliums-eluting stents (SES) and paclitaxel-eluting stents (PES) have been widely used for the treatment of coronary artery disease. We investigated 5-year clinical outcomes of patients treated with SES versus PES in a multicenter registry.

Methods

We used a propensity score matching method with 2:1 matching, including 512 patients treated with SES and 256 patients treated with PES from March 2003 to December 2004. The primary endpoint was major adverse cardiac events, which included all-cause death, myocardial infarction (MI), and target vessel revascularization (TVR).

Results

After matching, baseline characteristics were similar between the two groups. At 5 years, cumulative survival free of major adverse cardiac events, MI, and stent thrombosis did not differ between the two groups. Survival free of TVR at 5 years was higher in the SES group (88.4%) than the PES group (84.3%, Log-rank p = 0.016). In contrast to the trend toward more likely target lesion revascularization in the PES group during the first 2 years (hazard ratio 0.62, p = 0.057), target lesion revascularization tended to occur more frequently in the SES group from 2 to 5 years (hazard ratio 2.26, p = 0.099).

Conclusions

Long-term risk of TVR was slightly lower with SES, compared with PES, despite no significant difference in major adverse cardiac events. However, the SES group had more frequent target lesion reintervention 2 to 5 years after stent implantation, whereas reintervention in the PES group occurred mainly within the first 2 years. This may reflect the temporal difference in neointimal growth of the two stent types.  相似文献   
990.
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