全文获取类型
收费全文 | 4995篇 |
免费 | 423篇 |
国内免费 | 39篇 |
专业分类
耳鼻咽喉 | 114篇 |
儿科学 | 176篇 |
妇产科学 | 96篇 |
基础医学 | 649篇 |
口腔科学 | 109篇 |
临床医学 | 496篇 |
内科学 | 931篇 |
皮肤病学 | 64篇 |
神经病学 | 400篇 |
特种医学 | 212篇 |
外国民族医学 | 1篇 |
外科学 | 816篇 |
综合类 | 183篇 |
一般理论 | 2篇 |
预防医学 | 423篇 |
眼科学 | 54篇 |
药学 | 500篇 |
肿瘤学 | 231篇 |
出版年
2021年 | 61篇 |
2020年 | 41篇 |
2019年 | 67篇 |
2018年 | 90篇 |
2017年 | 71篇 |
2016年 | 97篇 |
2015年 | 95篇 |
2014年 | 144篇 |
2013年 | 178篇 |
2012年 | 267篇 |
2011年 | 259篇 |
2010年 | 156篇 |
2009年 | 167篇 |
2008年 | 250篇 |
2007年 | 276篇 |
2006年 | 239篇 |
2005年 | 219篇 |
2004年 | 181篇 |
2003年 | 157篇 |
2002年 | 176篇 |
2001年 | 151篇 |
2000年 | 168篇 |
1999年 | 123篇 |
1998年 | 72篇 |
1997年 | 63篇 |
1996年 | 72篇 |
1995年 | 54篇 |
1994年 | 34篇 |
1993年 | 46篇 |
1992年 | 99篇 |
1991年 | 84篇 |
1990年 | 70篇 |
1989年 | 93篇 |
1988年 | 73篇 |
1987年 | 106篇 |
1986年 | 81篇 |
1985年 | 78篇 |
1984年 | 53篇 |
1983年 | 50篇 |
1982年 | 36篇 |
1981年 | 33篇 |
1980年 | 40篇 |
1979年 | 51篇 |
1978年 | 47篇 |
1977年 | 38篇 |
1975年 | 43篇 |
1974年 | 39篇 |
1973年 | 36篇 |
1972年 | 32篇 |
1970年 | 37篇 |
排序方式: 共有5457条查询结果,搜索用时 15 毫秒
81.
Angiotension-converting enzyme gene I/D polymorphism in patients with angina and normal coronary arteriograms 总被引:3,自引:0,他引:3
Vázquez-Rey E Montgomery HE Arroyo-Espliguero R Brown S Kaski JC 《International journal of cardiology》2005,98(2):339-340
A polymorphism of the human angiotensin-converting enzyme (ACE) gene has been identified in which the insertion (I) rather than the deletion (D) variant is associated with lower circulating and tissue ACE activity. ACE I allele is associated with resistance and endurance performance. Skeletal muscle metabolic efficiency is reduced in patients with heart failure and is improved by ACE inhibition. Profound muscle fatigue is a predominant and debilitating symptom in a proportion or patients with angina and normal coronary arteriograms (ANCA), and we postulated that the gene D allele might be associated with the presence of fatigue in ANCA patients. We studied 33 consecutive patients with typical ANCA who completed a validated fatigue questionnaire, and found an excess of the D allele frequency in patients with the highest fatigue scores compared to those with the lowest (64% vs. 36%; p=0.027). 相似文献
82.
To establish whether pressure-volume areas (PVAs) calculated using the maximum time-varying elastance (Emax) have a relation with myocardial oxygen consumption (MVO2) that improves on other indexes of myocardial oxygen demand, we studied nine dogs of either sex weighing 19-39 kg, which were instrumented with a micromanometer left ventricular (LV) catheter and a Wilton-Webster coronary sinus flow catheter and had red blood cells tagged with technetium-99m for radionuclide angiography. Hemodynamics, coronary sinus flow determinations, and radionuclide angiograms were obtained under control conditions and during three to five steady-state loading conditions (mean +/- SD, 5.6 +/- 0.7). Isochronal pressure-volume data points from each pressure-volume loop were subjected to linear regression analysis to calculate Emax. The Emax relations, diastolic curves, and systolic portions of each pressure-volume loop were used to obtain calibrated PVAs. The Emax PVA (mm Hg.ml.beat-1.100 g-1) and MVO2 (ml O2.beat-1.100 g-1) values correlated in each animal (r = 0.77 to 0.99). Their slopes averaged (3.48 +/- 1.68) x 10(-5) ml O2.mm Hg-1.ml-1, and their y-axis intercepts averaged 0.07 +/- 0.04 ml O2.beat-1.100 g-1. When the MVO2 relations were compared with Emax PVA, LV systolic pressure-rate product, LV stroke work, and a modification of the LV pressure-work index, the Emax PVA, LV systolic pressure-rate product, and LV pressure-work index had similar relations with MVO2, whereas LV stroke work was a weaker index of MVO2 (p less than 0.05 versus Emax PVA). This occurred because the Emax PVA:MVO2 slopes and y-axis intercepts differed in each dog, which was due to differences in basal LV contractility. The Emax PVA:MVO2 slopes correlated with Emax (r = 0.73, p less than 0.05), and the y-axis intercepts were also weakly related to Emax (r = 0.48, p = 0.19). We conclude that the Emax PVAs calculated using data acquisition techniques that are clinically applicable have relations with MVO2 that in general do not improve on other indexes of myocardial oxygen demand in this animal preparation. 相似文献
83.
Transfusion of leukoreduced blood products and risk of antibody‐mediated rejection of renal allografts 下载免费PDF全文
84.
Cold storage of platelets in platelet additive solution: an in vitro comparison of two Food and Drug Administration–approved collection and storage systems 下载免费PDF全文
85.
Atujuna Millicent Montgomery Elizabeth T. Hartmann Miriam Ndwayana Sheily Browne Erica N. Sindelo Siyaxolisa Bekker Linda-Gail Minnis Alexandra M. 《AIDS and behavior》2022,26(5):1618-1632
AIDS and Behavior - While pre-exposure prophylaxis (PrEP) is a key HIV prevention tool for adolescents and young adults (AYAs), its initiation and sustained use is shaped by AYAs’ unique... 相似文献
86.
Paolo Ventura Herbert L. Bonkovsky Laurent Gouya Paula Aguilera-Peir D. Montgomery Bissell Penelope E. Stein Manisha Balwani D. Karl E. Anderson Charles Parker David J. Kuter Susana Monroy Jeeyoung Oh Bruce Ritchie John J. Ko Zhaowei Hua Marianne T. Sweetser Eliane Sardh 《Liver international》2022,42(1):i-i
87.
G Guroff P Montgomery N Tolson M E Lewis D End 《Proceedings of the National Academy of Sciences of the United States of America》1980,77(8):4607-4609
Renin-free nerve growth factor causes the induction of ornithine decarboxylase (L-ornithine carboxy-lyase, EC 4.1.1.17) in superior cervical ganglia from neonatal rats but not in the brain of mature rats. Less pure preparations of nerve growth factor induce the enzyme in both brain and ganglia. The induction of ornithine decarboxylase in the central nervous system appears to be due to renin, not to nerve growth factor itself. 相似文献
88.
89.
Small-bowel bacterial overgrowth in elderly people: clinical significance and response to treatment.
Duodenal-jejunal bacterial overgrowth is increasingly recognized in old age but its clinical significance is poorly defined. In this study, 16 elderly subjects were selected on the basis of an abnormal lactulose breath hydrogen test from a series of 27 in whom there was some reason to suspect malabsorption. In 12 of these 16 cases, pentagastrin tests showed normal gastric acid secretion and in 12 cases the small bowel was radiologically normal. Nutritional assessment, anthropometric measurements, culture of small-bowel aspirates, 14C-triolein breath tests and blood xylose tests were performed before and after 4 to 6 months of cyclical antibiotic therapy. Initially all patients except two showed evidence of malabsorption. After antibiotic treatment alone, 13 patients gained in weight and body fat. There were significant rises in the mean levels of haemoglobin, serum protein and calcium. Blood xylose test levels increased in 14 cases, reaching normal in all except one, whereas 14C-triolein excretion also increased in 14 and reached normal in 12 out of 16 cases. The breath hydrogen test reverted to normal in all cases and bacterial overgrowth was eliminated in 10 out of 11. The mouth-to-caecum transit time was prolonged initially (mean 190 min) and was unaffected by therapy (mean 196 min). Malabsorption and undernutrition are significant features of small-bowel overgrowth in the elderly and can be specifically corrected by antibiotic treatment. The clinical effect can be equally severe in elderly patients with or without an anatomical defect of the small bowel.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
90.
A B Montgomery J M Luce J F Murray 《The American review of respiratory disease》1989,139(6):1548-1550
To determine the most sensitive early indicator of toxicity from exposure to O2, we measured respiratory clearance of 99mTc-diethylenetriamine pentaacetate (Tc-DTPA), pulmonary function, serum Factor VIII antigen, and plasma fibronectin values and monitored symptoms in six normal volunteers who breathed 21, 40, and 100% O2, administered in random order, for 17 h at least 1 wk apart. Twenty minutes after beginning O2, arterial PO2 differed among the three exposure groups. After exposure to the three concentrations of O2, there were no differences in Tc-DTPA clearance, vital capacity, FEV1/FVC, diffusing capacity, Factor VIII antigen, or fibronectin concentration. In contrast, all subjects complained of retrosternal pain during and after breathing 100% O2 (p less than 0.001). We conclude that with exposure to 100% O2, retrosternal pain, presumably from tracheal inflammation, occurs before detectable abnormalities of epithelial solute permeability (Tc-DTPA clearance), endothelial O2 injury (fibronectin concentration and Factor VIII), or pulmonary function. These findings indicate that symptoms are more sensitive than signs in detecting early O2 toxicity. 相似文献