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   34314篇
  免费   3262篇
  国内免费   62篇
耳鼻咽喉   230篇
儿科学   1140篇
妇产科学   1062篇
基础医学   5024篇
口腔科学   629篇
临床医学   4304篇
内科学   6892篇
皮肤病学   531篇
神经病学   3276篇
特种医学   849篇
外科学   3937篇
综合类   647篇
一般理论   42篇
预防医学   3832篇
眼科学   407篇
药学   2704篇
中国医学   49篇
肿瘤学   2083篇
  2023年   284篇
  2022年   333篇
  2021年   824篇
  2020年   536篇
  2019年   901篇
  2018年   936篇
  2017年   635篇
  2016年   720篇
  2015年   781篇
  2014年   989篇
  2013年   1472篇
  2012年   2168篇
  2011年   2194篇
  2010年   1145篇
  2009年   1060篇
  2008年   1662篇
  2007年   1866篇
  2006年   1787篇
  2005年   1585篇
  2004年   1518篇
  2003年   1427篇
  2002年   1341篇
  2001年   780篇
  2000年   747篇
  1999年   704篇
  1998年   338篇
  1997年   336篇
  1996年   269篇
  1995年   278篇
  1994年   203篇
  1993年   220篇
  1992年   549篇
  1991年   523篇
  1990年   460篇
  1989年   544篇
  1988年   442篇
  1987年   408篇
  1986年   447篇
  1985年   359篇
  1984年   318篇
  1983年   337篇
  1982年   192篇
  1981年   191篇
  1979年   252篇
  1978年   195篇
  1977年   186篇
  1976年   174篇
  1974年   162篇
  1973年   184篇
  1971年   165篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Intratumor heterogeneity is a main cause of the dismal prognosis of glioblastoma (GBM). Yet, there remains a lack of a uniform assessment of the degree of heterogeneity. With a multiscale approach, we addressed the hypothesis that intratumor heterogeneity exists on different levels comprising traditional regional analyses, but also innovative methods including computer-assisted analysis of tumor morphology combined with epigenomic data. With this aim, 157 biopsies of 37 patients with therapy-naive IDH-wildtype GBM were analyzed regarding the intratumor variance of protein expression of glial marker GFAP, microglia marker Iba1 and proliferation marker Mib1. Hematoxylin and eosin stained slides were evaluated for tumor vascularization. For the estimation of pixel intensity and nuclear profiling, automated analysis was used. Additionally, DNA methylation profiling was conducted separately for the single biopsies. Scoring systems were established to integrate several parameters into one score for the four examined modalities of heterogeneity (regional, cellular, pixel-level and epigenomic). As a result, we could show that heterogeneity was detected in all four modalities. Furthermore, for the regional, cellular and epigenomic level, we confirmed the results of earlier studies stating that a higher degree of heterogeneity is associated with poorer overall survival. To integrate all modalities into one score, we designed a predictor of longer survival, which showed a highly significant separation regarding the OS. In conclusion, multiscale intratumor heterogeneity exists in glioblastoma and its degree has an impact on overall survival. In future studies, the implementation of a broadly feasible heterogeneity index should be considered.  相似文献   
2.
3.
4.

Objective

The “Centre Hospitalier Francois Dunan” is located on an isolated island and ensures patients care in hemodialysis thanks to telemedicine support. Many research studies have demonstrated the importance of hemodialysis fluids composition to reduce morbidity in patients on chronic hemodialysis. The aim of this study was to identify the risks inherent in the production of dialysis fluids in a particular context, in order to set up an improvement action plan to improve risk control on the production of dialysis fluids.

Methods

The risk analysis was conducted with the FMECA methodology (Failure Mode, Effects and Criticality Analysis) by a multi professional work group. Three types of risk have been reviewed: technical risks that may impact the production of hemodialysis fluids, health risks linked with chemical composition and health risks due to microbiological contamination of hemodialysis fluids.

Results

The work group, in close cooperation with the expert staff of the dialysis center providing telemedicine assistance, has developed an action plan in order to improve the control of the main risks brought to light by the risk analysis.

Conclusion

The exhaustive analysis of the risks and their prioritisation have permitted to establish a relevant action plan in this improving quality of dialysis fluids approach. The risk control of dialysis fluids is necessary for the security of dialysis sessions for patients, even more when these sessions are realized by telemedicine in Saint-Pierre-et-Miquelon.  相似文献   
5.
6.
7.
ABSTRACT

Objective

To investigate primary care physician clinical practice patterns, barriers, and education surrounding pediatric physical activity (PA), and to compare practice patterns by discipline.  相似文献   
8.

Objective

To systematically review literature on uptake and timeliness of diphtheria-tetanus-pertussis, measles-mumps-rubella, and/or polio-containing vaccines in infants who were born preterm, with a low birth weight, and/or with chronic health conditions that were diagnosed within the first 6?months of life.

Methods

Using a standardized search strategy developed by a medical librarian, records were extracted from MEDLINE, Embase, Database of Abstracts of Reviews of Effects, and CINAHL up to May 8, 2018.

Results

Out of the 1997 records that were screened, we identified 21 studies that met inclusion criteria. Eleven studies assessed vaccine coverage and/or timeliness in preterm infants, 6 in low birth weight infants, and 7 in children with chronic health conditions. Estimates of coverage in these populations were highly variable, ranging from 40% to 100% across the vaccines and population groups.

Conclusions

There is a lack of studies reporting coverage and timeliness of routine immunizations in special populations of children.

Policy implications

Our review suggests a need for improved surveillance of immunization status in special populations of infants, as well as a need for standardization of reporting practices.  相似文献   
9.

Background

Bone mineral density (BMD) has been found to improve after parathyroidectomy (PTX) in patients with primary hyperparathyroidism. There are few data on the effect of PTX on BMD in normocalcemic and normohormonal primary hyperparathyroidism.

Methods

A retrospective analysis of 92 primary hyperparathyroidism patients who underwent PTX between 2004 and 2012 with pre- and post-PTX dual-energy x-ray absorptiometry was performed. Within-person changes in BMD pre- and post-PTX were analyzed using log linear mixed models, stratified by biochemical status.

Results

Bone mineral density increased post-PTX in the whole cohort at the lumbar spine (+2.5%), femoral neck (+2.1%), and total hip (+1.9%) and decreased at the one-third radius (–0.9%). On comparison of BMD changes by profile, BMD increased in those with the typical profile at the lumbar spine (3.2%), femoral neck (2.9%), and total hip (2.9%) but declined at the one-third radius (–1.5%). In contrast, BMD improved only at the femoral neck (4.3%) in the normohormonal group and did not change at any site in the normocalcemic group. The typical group had a greater increase in BMD over time at the femoral neck and total hip compared with normocalcemic patients.

Conclusion

Our results indicate that the skeletal benefit of PTX was attenuated in normocalcemic and normohormonal patients, suggesting that skeletal changes after PTX may depend on biochemical profile.  相似文献   
10.
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