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   22703篇
  免费   1821篇
  国内免费   78篇
耳鼻咽喉   326篇
儿科学   648篇
妇产科学   507篇
基础医学   3159篇
口腔科学   463篇
临床医学   2063篇
内科学   5315篇
皮肤病学   262篇
神经病学   2061篇
特种医学   674篇
外科学   3744篇
综合类   306篇
一般理论   16篇
预防医学   1791篇
眼科学   585篇
药学   1269篇
中国医学   40篇
肿瘤学   1373篇
  2023年   162篇
  2022年   284篇
  2021年   799篇
  2020年   424篇
  2019年   634篇
  2018年   768篇
  2017年   508篇
  2016年   521篇
  2015年   634篇
  2014年   826篇
  2013年   1088篇
  2012年   1593篇
  2011年   1629篇
  2010年   869篇
  2009年   758篇
  2008年   1333篇
  2007年   1313篇
  2006年   1294篇
  2005年   1217篇
  2004年   1111篇
  2003年   988篇
  2002年   979篇
  2001年   196篇
  2000年   182篇
  1999年   203篇
  1998年   196篇
  1997年   178篇
  1996年   153篇
  1995年   138篇
  1994年   125篇
  1993年   126篇
  1992年   131篇
  1991年   125篇
  1990年   132篇
  1989年   112篇
  1988年   127篇
  1987年   130篇
  1986年   98篇
  1985年   130篇
  1984年   117篇
  1983年   114篇
  1982年   141篇
  1981年   140篇
  1980年   170篇
  1979年   95篇
  1978年   91篇
  1977年   91篇
  1976年   96篇
  1975年   71篇
  1974年   87篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
3.
4.

Background Context

Low back pain (LBP) is a common complaint in clinical practice of multifactorial origin. Although obesity has been thought to contribute to LBP primarily by altering the distribution of mechanical loads on the spine, the additional contribution of obesity-related conditions such as diabetes mellitus (DM) to LBP has not been thoroughly examined.

Purpose

To determine if there is a relationship between DM and LBP that is independent of body mass index (BMI) in a large cohort of adult survey participants.

Study Design

Retrospective analysis of prospectively collected National Health and Nutrition Examination Survey (NHANES) data to characterize associations between LBP, DM, and BMI in adults subdivided into 6 subpopulations: normal weight (BMI 18.5–25), overweight (BMI 25–30), and obese (BMI >30) diabetics and nondiabetics. Diabetes was defined with glycohemoglobin A1c (HbA1c) 6.5%.

Patient Sample

11,756 participants from NHANES cohort.

Outcome Measures

Percentage of LBP reported.

Methods

LBP reported in the 1999-2004 miscellaneous pain NHANES questionnaire was the dependent variable examined. Covariates included HbA1c, BMI, age, and family income ratio to poverty as continuous variables as well as race, gender, and smoking as binary variables. Individuals were further subdivided by weight class and diabetes status. Regression and graphical analyses were performed on the study population as a whole and also on subpopulations.

Results

Increasing HbA1c did not increase the odds of reporting LBP in the full cohort. However, multivariate logistic regression of the 6 subpopulations revealed that the odds of LBP significantly increased with increasing HbA1c levels in normal weight diabetics. No other subpopulations reported significant relationships between LBP and HbA1c. LBP was also significantly associated with BMI for normal weight diabetics and also for obese subjects regardless of their DM status.

Conclusions

LBP is significantly related to DM status, but this relationship is complex and may interact with BMI. These results support the concept that LBP may be improved in normal weight diabetic subjects with improved glycemic control and weight loss, and that all obese LBP subjects may benefit from improved weight loss alone.  相似文献   
5.
6.
7.
8.
This work describes the synthesis and tumor affinity testing of 8-[123I]iodo-l-1,2,3,4-tetrahydro-7-hydroxyisoquinoline-3-carboxylic acid [ITIC(OH)], a cyclic non-naturally occurring amino acid as an imaging probe for prostate cancer. Parameters for labelling were optimized with regard to the amount of precursor, the temperature and time. Thereafter, ITIC(OH) was evaluated in terms of its uptake in primary human PC-3 and DU-145 prostate cancer cells, followed by analysis of the underlying mechanisms of the radioactivity accumulation in tumor cells. No-carrier-added ITIC(OH) was obtained in 80+/-15% radiochemical yield and >98% radiochemical purity by a one-step radioiodination, using IODO-GEN as oxidant. The total synthesis time was less than 30 min, and compatible with a clinical routine production. ITIC(OH) accumulated intensively in primary human prostate cancer cells. The radioactivity incorporation in tumor following a 10-min incubation at 37 degrees C/pH 7.4 varied from 35% to 58% of the total loaded activity per 10(6) tumor cells (355-540 cpm/1000 cells). Inhibition experiments revealed that ITIC(OH) was taken up into tumor by an active transport different from the common amino acid carrier systems, including the sodium-dependent system A and B+,0, and the sodium-independent L- and ASC-type transporter. In contrast, the cellular incorporation was dependent on the membrane potential and correlated with the activity of the mitochondria. In conclusion, the specific and high-level accumulation of ITIC(OH) in human prostate carcinoma cells, indicates that the new radiopharmaceutical is a good candidate for further in vivo investigations to ascertain its potential as an imaging probe for prostate cancer by SPET.  相似文献   
9.
10.
BACKGROUND: Posterior spinal procedures through tubular exposures have been described. However, tubes restrain visibility and require co-axial instrument manipulation, increasing difficulty and potentially compromising surgical results. An independent-blade retractor system overcomes the obstacles of working through a tube and has been used to perform minimally-disruptive decompression and instrumented tranforaminal lumbar interbody fusion (TLIF). PURPOSE: To evaluate the advantages to patient recovery and surgical efficacy of this technique. METHODS/RESULTS: Retrospective review of technique employing a minimally-disruptive approach to decompression and transforaminal lumber interbody fusion (TLIF). CONCLUSIONS: Minimally-disruptive decompression and instrumented TLIF can be performed in a safe and effective manner using an independent-blade retractor system. Relative to traditional-open techniques, surgical goals can be accomplished, but with the benefits of minimally-disruptive surgery.  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