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   3775篇
  免费   259篇
  国内免费   21篇
耳鼻咽喉   62篇
儿科学   131篇
妇产科学   140篇
基础医学   412篇
口腔科学   105篇
临床医学   349篇
内科学   747篇
皮肤病学   120篇
神经病学   165篇
特种医学   170篇
外国民族医学   8篇
外科学   461篇
综合类   79篇
预防医学   349篇
眼科学   108篇
药学   395篇
中国医学   14篇
肿瘤学   240篇
  2023年   50篇
  2022年   157篇
  2021年   242篇
  2020年   138篇
  2019年   158篇
  2018年   221篇
  2017年   148篇
  2016年   133篇
  2015年   135篇
  2014年   168篇
  2013年   247篇
  2012年   301篇
  2011年   273篇
  2010年   189篇
  2009年   127篇
  2008年   154篇
  2007年   133篇
  2006年   137篇
  2005年   140篇
  2004年   124篇
  2003年   106篇
  2002年   81篇
  2001年   56篇
  2000年   50篇
  1999年   53篇
  1998年   15篇
  1997年   15篇
  1996年   16篇
  1995年   10篇
  1994年   7篇
  1993年   6篇
  1992年   12篇
  1991年   26篇
  1990年   22篇
  1989年   25篇
  1988年   14篇
  1987年   9篇
  1986年   21篇
  1985年   23篇
  1984年   10篇
  1983年   11篇
  1982年   8篇
  1980年   8篇
  1979年   10篇
  1978年   18篇
  1976年   5篇
  1975年   8篇
  1973年   5篇
  1971年   4篇
  1965年   5篇
排序方式: 共有4055条查询结果,搜索用时 15 毫秒
101.
BACKGROUND: Many members of the human kallikrein gene family are differentially expressed in cancer and a few have potential as diagnostic/prognostic markers. KLK14 is a newly discovered human kallikrein gene that is mainly expressed in the central nervous system and endocrine tissues. Since KLK14 was found to be regulated by steroid hormones in prostate cancer cell lines, we hypothesized that it will be differentially expressed in prostate cancer tissues compared to their normal counterparts. METHODS: Matched prostate tissue samples from the cancerous and non-cancerous parts of the same prostates were obtained from 100 patients who underwent radical prostatectomy. Quantitative analysis of KLK14 expression levels were performed by real-time RT-PCR using SYBR Green I dye on the LightCycler trade mark system. Associations with clinico-pathological parameters were analyzed. RESULTS: KLK14 overexpression in the cancerous compared to non-cancerous tissue was found in 74% of patients (P < 0.001). Mean level of expression was 154 arbitrary units (Au) in cancerous tissues and 14.2 Au in the non-cancerous tissues. The ratio of the cancerous to non-cancerous KLK14 expression values was higher in patients with late stage (stage III) compared to stage II (P = 0.002), and in grade 3 compared to grade 1/2 tumors (P = 0.001). A statistically significant increase was also observed in patients with higher in Gleason score (>6) compared to Gleason score = 6 tumors (P = 0.027). No correlation was found between KLK14 tissue expression levels and serum prostate-specific antigen. CONCLUSIONS: KLK14 expression is significantly higher in cancerous compared to non-cancerous prostatic tissue. The up-regulation of the KLK14 gene in advanced and more aggressive tumors may indicate a possible role for the hK14 protein in tumor spread and opens the possibility of hK14 being a candidate new marker for prostate cancer diagnosis and prognosis.  相似文献   
102.

Background

Diagnosis of appendicitis is still clinically challenging where resources are limited. The purpose of this study was to develop and externally validate Ramathibodi Appendicitis Score (RAMA-AS) in aiding diagnosis of appendicitis.

Methods

A two-phase cross-sectional study (i.e., derivation and validation) was conducted at Ramathibodi Hospital (for derivation) and at Thammasat University Hospital and Chaiyaphum Hospital (for validation). Patients with abdominal pain and suspected of having appendicitis were enrolled. Multiple logistic regression was applied to develop a parsimonious model. Calibration and discrimination performances were assessed. In addition, our RAMA-AS was compared with Alvarado’s score performances using ROC curve analysis.

Results

The RAMA-AS consisted of three domains with seven predictors including symptoms (i.e., progression of pain, aggravation of pain, and migration of pain), signs (i.e., fever and rebound tenderness), and laboratory tests (i.e., white blood cell count (WBC) and neutrophil). The model fitted well with data, and it performed better discrimination than the Alvarado score with C-statistics of 0.842 (95% CI 0.804, 0.881) versus 0.760 (0.710, 0.810). Internal validation by bootstrap yielded Sommer’s D of 0.686 (0.608, 0.763) and C-statistics of 0.848 (0.846, 0.849). The C-statistics of two external validations were 0.853 (0.791, 0.915) and 0.813 (0.736, 0.892) with fair calibrations.

Conclusion

RAMA-AS should be a useful tool for aiding diagnosis of appendicitis with good calibration and discrimination performances.
  相似文献   
103.

Introduction

Despite its minimally invasive approach, laparoscopic surgery can cause considerable pain. Regional analgesic techniques such as the rectus sheath block (RSB) offer improved pain management following elective umbilical hernia repair in the pediatric population. This effect has not been examined in laparoscopic single-incision surgery in children. We sought to compare the efficacy of bilateral ultrasound-guided RSB versus local anesthetic infiltration (LAI) in providing postoperative pain relief in pediatric single-incision transumbilical laparoscopic assisted appendectomy (TULA) with same-day discharge.

Methods

We retrospectively reviewed 275 children, ages 4 to 17 years old, who underwent TULA for uncomplicated appendicitis in a single institution from August 2014 to July 2015. We compared those that received preincision bilateral RSB (n = 136) with those who received LAI (n = 139). The primary outcome was narcotic administration. Secondary outcomes included initial and mean scores, time from anesthesia induction to release, operative time, time to rescue dose of analgesic in the PACU and time to PACU discharge.

Results

Total narcotic administration was significantly reduced in patients that underwent preincision RSB compared to those that received conventional LAI, with a mean of 0.112 mg/kg of morphine versus 0.290 mg/kg morphine (p < 0.0001). Patients undergoing RSB reported lower initial (0.38 vs. 2.38; p < 0.0001) and mean pain scores (1.26 vs. 1.77; p < 0.015). Time to rescue analgesia was prolonged in patients undergoing RSB compared to LAI (58.93 min vs. 41.56 min; p = 0.047).

Conclusion

Preincision RSB for TULA in uncomplicated appendicitis in children is associated with decreased opioid consumption and lower pain scores compared with LAI. As the addition of this procedure only added 6.67 min to time under anesthesia, we feel that it is a viable option for postoperative pain control in pediatric single-incision laparoscopic surgery.

Retrospective comparative study

LEVEL III EVIDENCE.  相似文献   
104.
INTRODUCTION: Acetaminophen (paracetamol) overdose (AOD) has recently emerged as the leading cause of acute liver failure (ALF) in the United States, with an incidence approaching that seen in the United Kingdom. We describe a new way to treat AOD ALF patients fulfilling King's College criteria for "super-urgent" liver transplantation. METHODS: Beginning in June 1998, we have been piloting a clinical program of subtotal hepatectomy and auxiliary orthotopic liver transplantation (ALT) for AOD ALF. Our technique is based on the following principles: (1) subtotal hepatectomy; (2) auxiliary transplantation of a whole liver graft; (3) gradual withdrawal of immunosuppression after recovery. Results were compared with patients who had undergone an orthotopic liver transplantation (OLT) for AOD ALF in the same period. Quality of life comparisons were made using the SF36 questionnaire. RESULTS: Thirteen patients underwent this procedure between June 1998 and March 2005. Median survival is 68 months (range, 0-102 m). Actual survival data show that 9 of 13 patients are alive (69%) compared with 7 of 13 OLT patients (54%). One ALT patient required a retransplantation with an OLT due to hepatic vein thrombosis, and immunosuppression is therefore maintained. The other 8 surviving ALT patients are off immunosuppression. These 8 ALT patients have normal liver function and have a better quality of life compared with the 7 surviving OLT patients. CONCLUSION: Our results with this new technique are encouraging: 69% actual survival, no long-term immunosuppression requirement, and improved quality of life in the 62% successful cases.  相似文献   
105.
106.
107.
Electrospinning (ES) has become a straightforward and customizable drug delivery technique for fabricating drug-loaded nanofibers (NFs) using various biodegradable and non-biodegradable polymers. One of NF’s pros is to provide a controlled drug release through managing the NF structure by changing the spinneret type and nature of the used polymer. Electrospun NFs are employed as implants in several applications including, cancer therapy, microbial infections, and regenerative medicine. These implants facilitate a unique local delivery of chemotherapy because of their high loading capability, wide surface area, and cost-effectiveness. Multi-drug combination, magnetic, thermal, and gene therapies are promising strategies for improving chemotherapeutic efficiency. In addition, implants are recognized as an effective antimicrobial drug delivery system overriding drawbacks of traditional antibiotic administration routes such as their bioavailability and dosage levels. Recently, a sophisticated strategy has emerged for wound healing by producing biomimetic nanofibrous materials with clinically relevant properties and desirable loading capability with regenerative agents. Electrospun NFs have proposed unique solutions, including pelvic organ prolapse treatment, viable alternatives to surgical operations, and dental tissue regeneration. Conventional ES setups include difficult-assembled mega-sized equipment producing bulky matrices with inadequate stability and storage. Lately, there has become an increasing need for portable ES devices using completely available off-shelf materials to yield highly-efficient NFs for dressing wounds and rapid hemostasis. This review covers recent updates on electrospun NFs in nanomedicine applications. ES of biopolymers and drugs is discussed regarding their current scope and future outlook.  相似文献   
108.
109.
Background: Large atrial septal defects (ASDs) in children cause increased volume overload of the right side of the heart which in turn lead to impairment of left ventricular (LV) performance. Aim: The aim of this study was to evaluate immediate LV rotational deformation changes in children with large ASDs post-device closure and removal of right ventricle (RV) volume overload. Patients and Methods: Twenty children who underwent transcatheter closure (TCC) of large secundum ASDs were included in the study. LV rotational deformation was assessed pre- and 24 hours post-device closure using speckle tracking imaging (STI). Results: 55% were females with mean age 6.1 ± 3.5 years. LV peak basal clockwise rotation improved significantly (−6.9 ± 2.6° before vs −10.3 ± 4.1° after TCC, P = .005), and time to peak clockwise rotation (345.1 ± 124.7 milliseconds (ms) before vs 282.2 ± 82.9 ms after closure, P = .02). There was no significant difference in apical rotational parameters including peak counterclockwise rotation (P > .05 for both). LV twist (11.3 ± 3.8° before vs 17.5 ± 7.1° after closure, P = .001) and torsion (2.1 ± 0.7°/cm before vs 3.1 ± 1.2°/cm after closure, P = .01) were significantly improved, mainly as the result of improvement of LV basal rotation. LV revealed a significant increase in LV end-diastolic volumes (P = .02) 24 hour after TCC with no significant change (P > .05) in end-systolic volumes after closure. Conclusion: Increased peak LV twisting and torsion were attributed to the improved peak systolic clockwise basal rotation after TCC of large ASDs in children.  相似文献   
110.
The evolution of non-invasive hemoglobin measuring technology would save time and improve transfusion practice. The validity of pulse co-oximetry hemoglobin (SpHb) measurement in the perioperative setting was previously evaluated; however, the accuracy of SpHb in different volume statuses as well as in different perfusion states was not well investigated. The aim of this work is to evaluate the accuracy and trending of SpHb in comparison to laboratory hemoglobin (Lab-Hb) during acute bleeding and after resuscitation. Seventy patients scheduled for major orthopedic procedures with anticipated major blood loss were included. Radical-7 device was used for continuous assessment of SpHb, volume status [via pleth variability index (PVI)] and perfusion status [via perfusion index (PI)]. Lab-Hb and SpHb were measured at three time-points, a baseline reading, after major bleeding, and after resuscitation. Samples were divided into fluid-responsive and fluid non-responsive samples, and were also divided into high-PI and low-PI samples. Accuracy of SpHb was determined using Bland–Altman analysis. Trending of SpHb was evaluated using polar plot analysis. We obtained 210 time-matched readings. Fluid non-responsive samples were 106 (50.5%) whereas fluid responsive samples were 104 (49.5%). Excellent correlation was reported between Lab-Hb and SpHb (r?=?0.938). Excellent accuracy with moderate levels of agreement was also reported between both measures among all samples, fluid non-responsive samples, fluid-responsive samples, high-PI samples, and low-PI samples [Mean bias (limits of agreement): 0.01 (??1.33 and 1.34) g/dL, ??0.08 (??1.27 and 1.11) g/dL, 0.09 (??1.36 and 1.54) g/dL, 0.01 (??1.34 to 1.31) g/dL, and 0.04 (??1.31 to 1.39) g/dL respectively]. Polar plot analysis showed good trending ability for SpHb as a follow up monitor. In conclusion, SpHb showed excellent correlation with Lab-Hb in fluid responders, fluid non-responders, low-PI, and high PI states. Despite a favorable mean bias of 0.01 g/dL for SpHb, the relatively wide levels of agreement (??1.3 to 1.3 g/dL) might limit its accuracy. SpHb showed good performance as a trend monitor.  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