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   34947篇
  免费   1638篇
  国内免费   259篇
耳鼻咽喉   337篇
儿科学   630篇
妇产科学   387篇
基础医学   4353篇
口腔科学   639篇
临床医学   2111篇
内科学   9042篇
皮肤病学   1459篇
神经病学   2955篇
特种医学   1475篇
外科学   5762篇
综合类   164篇
预防医学   844篇
眼科学   525篇
药学   2461篇
中国医学   67篇
肿瘤学   3633篇
  2023年   201篇
  2022年   440篇
  2021年   793篇
  2020年   407篇
  2019年   530篇
  2018年   765篇
  2017年   604篇
  2016年   719篇
  2015年   765篇
  2014年   945篇
  2013年   1154篇
  2012年   1821篇
  2011年   2044篇
  2010年   1223篇
  2009年   1042篇
  2008年   1858篇
  2007年   1974篇
  2006年   1969篇
  2005年   1960篇
  2004年   2003篇
  2003年   1865篇
  2002年   1818篇
  2001年   761篇
  2000年   778篇
  1999年   793篇
  1998年   497篇
  1997年   371篇
  1996年   312篇
  1995年   308篇
  1994年   259篇
  1993年   238篇
  1992年   527篇
  1991年   485篇
  1990年   467篇
  1989年   497篇
  1988年   450篇
  1987年   412篇
  1986年   368篇
  1985年   333篇
  1984年   221篇
  1983年   198篇
  1982年   113篇
  1981年   108篇
  1980年   87篇
  1979年   181篇
  1978年   108篇
  1977年   108篇
  1975年   86篇
  1973年   92篇
  1972年   94篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Surgery Today - We introduced a superior approach and a unique technique to retract the stomach, called the “stomach roll-up technique”, to standardize laparoscopic distal...  相似文献   
992.
An automated assay of plasma prekallikrein is described. Prekallikrein was converted to kallikrein with Pseudomonas aeruginosa elastase, and the hydrolytic activity of kallikrein to H-D-Pro-Phe-Arg-paranitroanilide subsequently measured.

The conversion was complete within 8 minutes and the amidolytic activity remained stable at least another 10 min at 37 ° C. This method worked in plasma deficient in Hageman factor (blood coagulation factor XII). Using anti-prekallikrein antibody and plasma deficient in prekallikrein, the amidolytic activity generated in normal plasma was identified as due to kallikrein. With plasma samples, the coefficients of variation (CV) for multiple measurements within run (n = 10) and between run (n = 10) were as low as 5.0% and 6.6%, respectively, and the minimum measurable concentration of prekallikrein in plasma was 10% of the normal level.  相似文献   

993.
Humic acid (HA), a group of high‐molecular weight organic compounds characterized by an ability to bind heavy metals, is normally found in natural water. Although the impairment of vascular endothelial cells in the presence of humic substances has been reported to be involved in some diseases, the mechanisms responsible for this involvement remain unclear. In this study, we examined the cytotoxicity of HA obtained from peatland in Central Kalimantan, Indonesia, to human vascular endothelial cells, as well as the mechanisms behind these effects. It was found that 50 mg/L HA showed cytotoxicity, which we considered to be mediated by apoptosis through the mitochondrial pathway because of an increase in the expression of caspases 6 and 9 in response to HA administration. In addition, this cytotoxicity was enhanced when cells in this experimental system were exposed to oxidative stress, while it was decreased by the addition of vitamin C. Thus, we conclude that the apoptosis induced by HA depends upon oxidative stress. Furthermore, an iron chelator, DFO, showed a tendency to decrease HA‐induced cytotoxicity, suggesting that iron may potentially mediate HA‐induced oxidative stress. In conclusion, long‐term consumption of HA‐rich water obtained from our study area may cause damage to endothelial cells and subsequent chronic health problems. © 2012 Wiley Periodicals, Inc. Environ Toxicol 29: 916–925, 2014.  相似文献   
994.

Purpose

Femoroacetabular impingement is a new disease concept for hip disorders in young adults suggested as a major cause of primary hip osteoarthritis in Western countries. However, significant controversy exists regarding the prevalence and contribution of impingement deformities to osteoarthritis in Japan, owing to the higher prevalence of developmental dysplasia of the hip. Therefore, the aims of this study were to: (1) determine the prevalence of structural abnormalities associated with hip disorders in patients undergoing total hip replacement and (2) analyse the contribution of impingement deformities to osteoarthritis.

Methods

We analysed 250 patients from two different medical centres who underwent primary total hip replacement except those which were due to femoral head necrosis, posttraumatic osteoarthritis and systemic inflammatory disease. The average patient age at surgery was 64 years (range, 40–89 years), with 35 men and 215 women.

Results

Radiographic abnormality related to developmental dysplasia of the hip was associated with the majority of osteoarthritic hips (62 %). Hips with femoroacetabular impingement deformities were present within the cases categorized as unknown etiology. Cam impingement deformity was present in 22 % of unknown aetiology cases when cases with reactive osteophytes were excluded from all cam deformity cases (pistol grip deformity and aspherical femoral heads).

Conclusions

The prevalence of femoroacetabular impingement within primary osteoarthritis cases and gender predominance of impingement deformities are relatively similar to those reported previously in Western populations. This finding indicates that femoroacetabular impingement deformities are associated with osteoarthritis in the Japanese population, although it has a lower frequency among all hip failure patients.  相似文献   
995.
The complex anatomy of the sacrum makes surgical fracture fixation challenging. We developed statistical models to investigate sacral anatomy with special regard to trans‐sacral implant fixation. We used computed tomographies of 20 intact adult pelves to establish 3D statistical models: a surface model of the sacrum and the trans‐sacral corridor S1, including principal component analysis (PCA), and an averaged gray value model of the sacrum given in Hounsfield Units. PCA demonstrated large variability in sacral anatomy markedly affecting the diameters of the trans‐sacral corridors. The configuration of the sacral alae and the vertical position of the auricular surfaces were important determinants of the trans‐sacral corridor dimension on level S1. The statistical model of trans‐sacral corridor S1 including the adjacent parts of the iliac bones showed main variation in length; however, the diameter was the main criterion for the surgically available corridor. The averaged gray value model revealed a distinct pattern of bone mass distribution with lower density particularly in the sacral alae. These advanced 3D statistical models provide a thorough anatomical understanding demonstrating the impact of sacral anatomy on positioning trans‐sacral implants. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:1543–1548, 2014.  相似文献   
996.
997.
998.

Background

The benefit of cytoreductive nephrectomy (CN) for overall survival (OS) is unclear in patients with synchronous metastatic renal cell carcinoma (mRCC) in the era of targeted therapy.

Objective

To determine OS benefit of CN compared with no CN in mRCC patients treated with targeted therapies.

Design, setting, and participants

Retrospective data from patients with synchronous mRCC (n = 1658) from the International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) were used to compare 982 mRCC patients who had a CN with 676 mRCC patients who did not.

Outcome measurements and statistical analysis

OS was compared and hazard ratios (HRs) adjusted for IMDC poor prognostic criteria.

Results and limitations

Patients who had CN had better IMDC prognostic profiles versus those without (favorable, intermediate, or poor in 9%, 63%, and 28% vs 1%, 45%, and 54%, respectively). The median OS of patients with CN versus without CN was 20.6 versus 9.5 mo (p < 0.0001). When adjusted for IMDC criteria to correct for imbalances, the HR of death was 0.60 (95% confidence interval, 0.52–0.69; p < 0.0001). Patients estimated to survive <12 mo may receive marginal benefit from CN. Patients who have four or more of the IMDC prognostic criteria did not benefit from CN. Data were collected retrospectively.

Conclusions

CN is beneficial in synchronous mRCC patients treated with targeted therapy, even after adjusting for prognostic factors. Patients with estimated survival times <12 mo or four or more IMDC prognostic factors may not benefit from CN. This information may aid in patient selection as we await results from randomized controlled trials.

Patient summary

We looked at the survival outcomes of metastatic renal cell carcinoma patients who did or did not have the primary tumor removed. We found that most patients benefited from tumor removal, except for those with four or more IMDC risk factors.  相似文献   
999.

Purpose

Recent studies have shown that the modified Glasgow Prognostic Score (mGPS), which is an inflammation-based prognostic score, is useful as a prognostic index for some cancer cases. The purpose of this study was to create a prognostic scoring system for patients with esophageal squamous cell carcinoma (ESCC) that was more independent and sensitive than the mGPS.

Methods

One hundred sixty-eight patients who had undergone esophagectomy for ESCC were included in the study. The new mGPS (NmGPS) was calculated based on the following cutoff values: CRP >0.75 mg/dL indicated NmGPS 1 or 2, depending on the absence or presence of hypoalbuminemia (<3.5 g/dL); and CRP ≤0.75 mg/dL indicated NmGPS 0. We also performed an analysis based on cutoff values of 0.5 and 0.25 mg/dL for CRP.

Results

Only the NmGPS with a cutoff CRP value of 0.5 mg/dL was able to divide into three independent patient groups in the survival curves. In the multivariate analyses, a NmGPS (CRP cutoff; 0.5 mg/dL) of 2 was a more significant independent prognostic factor (HR 4.437, 95 % CI 2.000–9.844, p = 0.0002) than a mGPS of 2 (HR 2.726, 95 % CI 1.021–7.112, p = 0.0449).

Conclusions

The new prognostic score NmGPS (CRP cutoff; 0.5 mg/dL) was more independent and sensitive than the mGPS for patients with ESCC.  相似文献   
1000.
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