全文获取类型
收费全文 | 3766篇 |
免费 | 235篇 |
国内免费 | 92篇 |
学科分类
医药卫生 | 4093篇 |
出版年
2021年 | 31篇 |
2020年 | 36篇 |
2019年 | 59篇 |
2018年 | 75篇 |
2017年 | 49篇 |
2016年 | 57篇 |
2015年 | 80篇 |
2014年 | 104篇 |
2013年 | 123篇 |
2012年 | 148篇 |
2011年 | 144篇 |
2010年 | 165篇 |
2009年 | 143篇 |
2008年 | 133篇 |
2007年 | 168篇 |
2006年 | 125篇 |
2005年 | 144篇 |
2004年 | 109篇 |
2003年 | 96篇 |
2002年 | 100篇 |
2001年 | 107篇 |
2000年 | 69篇 |
1999年 | 72篇 |
1998年 | 139篇 |
1997年 | 166篇 |
1996年 | 140篇 |
1995年 | 116篇 |
1994年 | 123篇 |
1993年 | 103篇 |
1992年 | 53篇 |
1991年 | 68篇 |
1990年 | 64篇 |
1989年 | 82篇 |
1988年 | 77篇 |
1987年 | 75篇 |
1986年 | 74篇 |
1985年 | 61篇 |
1984年 | 49篇 |
1983年 | 34篇 |
1982年 | 27篇 |
1981年 | 36篇 |
1980年 | 31篇 |
1979年 | 20篇 |
1978年 | 30篇 |
1977年 | 28篇 |
1976年 | 33篇 |
1975年 | 22篇 |
1974年 | 12篇 |
1971年 | 12篇 |
1968年 | 13篇 |
排序方式: 共有4093条查询结果,搜索用时 15 毫秒
1.
Tarik D. Madni Paul A. Nakonezny Evan Barrios Jonathan B. Imran Audra T. Clark Luis Taveras Holly B. Cunningham Alana Christie Alexander L. Eastman Christian T. Minshall Stephen Luk Joseph P. Minei Herb A. Phelan Michael W. Cripps 《American journal of surgery》2019,217(1):90-97
Background
The Parkland Grading Scale for Cholecystitis (PGS) was developed as an intraoperative grading scale to stratify gallbladder (GB) disease severity during laparoscopic cholecystectomy (LC). We aimed to prospectively validate this scale as a measure of LC outcomes.Methods
Eleven surgeons took pictures of and prospectively graded the initial view of 317?GBs using PGS while performing LC (LIVE) between 9/2016 and 3/2017. Three independent surgeon raters retrospectively graded these saved GB images (STORED). The Intraclass Correlation Coefficient (ICC) statistic assessed rater reliability. Fisher's Exact, Jonckheere-Terpstra, or ANOVA tested association between peri-operative data and gallbladder grade.Results
ICC between LIVE and STORED PGS grades demonstrated excellent reliability (ICC?=?0.8210). Diagnosis of acute cholecystitis, difficulty of surgery, incidence of partial and open cholecystectomy rates, pre-op WBC, length of operation, and bile leak rates all significantly increased with increasing grade.Conclusions
PGS is a highly reliable, simple, operative based scale that can accurately predict outcomes after LC.Table of contents summary
The Parkland Grading Scale for Cholecystitis was found to be a reliable and accurate predictor of laparoscopic cholecystectomy outcomes. Diagnosis of acute cholecystitis, surgical difficulty, incidence of partial and open cholecystectomy rates, pre-op WBC, operation length, and bile leak rates all significantly increased with increasing grade. 相似文献2.
Myles T. Taffel Lyndon Luk Justin M. Ream Andrew B. Rosenkrantz 《Journal l'Association canadienne des radiologistes》2019,70(4):416-423
PurposeTo evaluate whole-lesion 3D-histogram apparent diffusion coefficient (ADC) metrics for assessment of pancreatic malignancy.MethodsForty-two pancreatic malignancies (36 pancreatic adenocarcinoma [PDAC], 6 pancreatic neuroendocrine [PanNET]) underwent abdominal magnetic resonance imaging (MRI) with diffusion-weighted imaging before endoscopic ultrasound biopsy or surgical resection. Two radiologists independently placed 3D volumes of interest to derive whole-lesion histogram ADC metrics. Mann-Whitney tests and receiver operating characteristic analyses were used to assess metrics’ diagnostic performance for lesion histology, T-stage, N-stage, and grade.ResultsWhole-lesion ADC histogram metrics lower in PDACs than PanNETs for both readers (P ≤ .026) were mean ADC (area under the curve [AUC] = 0.787-0.792), mean of the bottom 10th percentile (mean0-10) (AUC = 0.787-0.880), mean of the 10th-25th percentile (mean10-25) (AUC = 0.884-0.917) and mean of the 25th-50th percentile (mean25-50) (AUC = 0.829-0.829). For mean10-25 (metric with highest AUC for identifying PDAC), for reader 1 a threshold > 0.94 × 10?3 mm2/s achieved sensitivity 94% and specificity 83%, and for reader 2 a threshold > 0.82 achieved sensitivity 97% and specificity 67%. Metrics lower in nodal status ≥ N1 than N0 for both readers (P ≤ .043) were mean0-10 (AUC = 0.789-0.822) and mean10-25 (AUC = 0.800-0.822). For mean10-25 (metric with highest AUC for identifying N0), for reader 1 a threshold <1.17 achieved sensitivity 87% and specificity 67%, and for reader 2 a threshold <1.04 achieved sensitivity 87% and specificity 83%. No metric was associated with T-stage (P > .195) or grade (P > .215).ConclusionVolumetric ADC histogram metrics may serve as non-invasive biomarkers of pancreatic malignancy. Mean10-25 outperformed standard mean for lesion histology and nodal status, supporting the role of histogram analysis. 相似文献
3.
Prevention Science - The current study tested and identified risk and protective pathways from alcohol expectancies to weekday and weekend consumption to problematic consequences. Adult alcohol... 相似文献
4.
5.
Sorokina E. G. Semenova Zh. B. Averianova N. S. Karaseva O. V. Arsenieva E. N. Luk’yanov V. I. Reutov V. P. Asanov A. Yu. Roshal L. M. Pinelis V. G. 《Neuroscience and behavioral physiology》2021,51(1):28-35
Neuroscience and Behavioral Physiology - Objective. To compare the genotypes at the apolipoprotein E (APOE) gene with outcomes and level of neural markers in children with severe traumatic brain... 相似文献
6.
Indra Neal Kar Denise L. Haynie Jeremy W. Luk Bruce G. Simons-Morton 《Substance use & misuse》2018,53(12):1984-1996
Background: Taxation and other policy measures have been implemented across the United States to curb the accessibility of substance use, especially among youth. While the inverse relationship between price and youth consumption is well known, available research on youth earned income and substance use is sparser, particularly among emerging adults. Objectives: We examined the association between emerging adult past-year personal income and 30-day substance use. Methods: We analyzed data from Wave 5 (n = 2,202) of the NEXT Generation Health Study, an annual survey study administered to a nationally representative sample of emerging adults in the U.S. Wave 5 (mean age = 20.28 years, SE = 0.02 years) was administered during the 2013–2014 academic year. After grouping participants into five levels of self-reported, pre-tax personal income, we used binomial logistic regression to examine the association between personal income and cigarette smoking, marijuana use, alcohol use, and heavy episodic drinking (HED). Results: In unadjusted models, those at certain levels of higher past-year income were more likely to smoke cigarettes, consume alcohol, or engage in HED at least once in the past 30 days. Several associations remained significant after controlling for covariates. Most associations were no longer significant after including perceived peer norms as additional covariates. Personal income was not associated with 30-day marijuana use in unadjusted or adjusted models. Conclusions/Importance: Higher earned income may provide emerging adults greater economic access to cigarettes and alcohol, but the association might be partly attenuated by social factors, particularly perceived peer norms. 相似文献
7.
Gian Luca Negri Bruno M Grande Alberto Delaidelli Amal El-Naggar Dawn Cochrane Ching C Lau Timothy J Triche Richard A Moore Steven JM Jones Alexandre Montpetit Marco A Marra David Malkin Ryan D Morin Poul H Sorensen 《The Journal of pathology》2019,249(3):319-331
Despite being the most common childhood bone tumor, the genomic characterization of osteosarcoma remains incomplete. In particular, very few osteosarcoma metastases have been sequenced to date, critical to better understand mechanisms of progression and evolution in this tumor. We performed an integrated whole genome and exome sequencing analysis of paired primary and metastatic pediatric osteosarcoma specimens to identify recurrent genomic alterations. Sequencing of 13 osteosarcoma patients including 13 primary, 10 metastatic, and 3 locally recurring tumors revealed a highly heterogeneous mutational landscape, including cases of hypermutation and microsatellite instability positivity, but with virtually no recurrent alterations except for mutations involving the tumor suppressor genes RB1 and TP53. At the germline level, we detected alterations in multiple cancer related genes in the majority of the cohort, including those potentially disrupting DNA damage response pathways. Metastases retained only a minimal number of short variants from their corresponding primary tumors, while copy number alterations showed higher conservation. One recurrently amplified gene, KDR, was highly expressed in advanced cases and associated with poor prognosis. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. 相似文献
8.
Šárka Rusá Arnošt Komárek Emmanuel Lesaffre Luk Bruyneel 《Statistics in medicine》2018,37(10):1650-1670
Although increasingly complex models have been proposed in mediation literature, there is no model nor software that incorporates the multiple possible generalizations of the simple mediation model jointly. We propose a flexible moderated mediation model allowing for (1) a hierarchical structure of clustered data, (2) more and possibly correlated mediators, and (3) an ordinal outcome. The motivating data set is obtained from a European study in nursing research. Patients' willingness to recommend their treating hospital was recorded in an ordinal way. The research question is whether such recommendation directly depends on system‐level features in the organization of nursing care, or whether these associations are mediated by 2 measurements of nursing care left undone and possibly moderated by nurse education. We have developed a Bayesian approach and accompanying program that takes all the above generalizations into account. 相似文献
9.
10.
Tse ET Cheng LY Luk HW Chu FC Chai J Chow TW 《The International journal of prosthodontics》2006,19(4):371-372
This study aimed to compare the retentive forces of cast cobalt-chromium (Co-Cr) and commercially pure titanium (cpTi) clasps. A clasp assembly comprising a pair of symmetrical clasps was made to fit the opposite halves of a hardened stainless-steel sphere. This twin clasp was designed to counterbalance the tipping forces when the clasp assembly was drawn from the sphere. A total of 120 clasp assemblies were fabricated in cast Co-Cr and cpTi and placed at undercut depths of 0.25 mm, 0.50 mm, and 0.75 mm (n = 20 for each). For Co-Cr clasps, the retentive forces at these undercuts depths were 2.34 +/- 0.23 N, 4.65 +/- 0.35 N, and 7.56 +/- 0.50 N, respectively. The corresponding retentive forces for cpTi clasps were 1.24 +/- 0.13 N, 2.34 +/- 0.23 N, and 3.70 +/- 0.27 N. The retentive force of cpTi clasps was approximately half that of Co-Cr clasps for the same undercut depth. 相似文献