全文获取类型
收费全文 | 46626篇 |
免费 | 4165篇 |
国内免费 | 71篇 |
专业分类
耳鼻咽喉 | 525篇 |
儿科学 | 1360篇 |
妇产科学 | 1073篇 |
基础医学 | 6008篇 |
口腔科学 | 1085篇 |
临床医学 | 5398篇 |
内科学 | 8808篇 |
皮肤病学 | 698篇 |
神经病学 | 4911篇 |
特种医学 | 2212篇 |
外国民族医学 | 4篇 |
外科学 | 6357篇 |
综合类 | 768篇 |
一般理论 | 34篇 |
预防医学 | 4410篇 |
眼科学 | 1179篇 |
药学 | 3152篇 |
2篇 | |
中国医学 | 53篇 |
肿瘤学 | 2825篇 |
出版年
2021年 | 587篇 |
2019年 | 556篇 |
2018年 | 653篇 |
2017年 | 558篇 |
2016年 | 561篇 |
2015年 | 657篇 |
2014年 | 882篇 |
2013年 | 1398篇 |
2012年 | 1936篇 |
2011年 | 2051篇 |
2010年 | 1164篇 |
2009年 | 1032篇 |
2008年 | 1833篇 |
2007年 | 2061篇 |
2006年 | 1950篇 |
2005年 | 1839篇 |
2004年 | 1798篇 |
2003年 | 1678篇 |
2002年 | 1710篇 |
2001年 | 1535篇 |
2000年 | 1559篇 |
1999年 | 1377篇 |
1998年 | 581篇 |
1997年 | 564篇 |
1996年 | 545篇 |
1995年 | 496篇 |
1994年 | 432篇 |
1993年 | 385篇 |
1992年 | 1171篇 |
1991年 | 1175篇 |
1990年 | 1108篇 |
1989年 | 1123篇 |
1988年 | 938篇 |
1987年 | 1055篇 |
1986年 | 979篇 |
1985年 | 988篇 |
1984年 | 766篇 |
1983年 | 626篇 |
1982年 | 404篇 |
1981年 | 374篇 |
1980年 | 380篇 |
1979年 | 702篇 |
1978年 | 526篇 |
1977年 | 456篇 |
1976年 | 466篇 |
1975年 | 400篇 |
1974年 | 520篇 |
1973年 | 455篇 |
1972年 | 383篇 |
1971年 | 363篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Joseph F Malouf Manfredi Ballo Heidi M Connolly David O Hodge Regina M Herges Charles J Mullany Fletcher A Miller 《Journal of the American Society of Echocardiography》2005,18(3):252-256
The purpose of this study was to provide, in a large number of patients, comprehensive Doppler echocardiographic assessment of normal St Jude Medical mitral valve prosthesis function using Doppler-derived hemodynamic variables, including the mitral valve prosthesis-to-left ventricular outflow tract time-velocity integral ratio and prosthesis performance index. The pressure half-time was less than 130 milliseconds in all patients, and all but one patient had either a peak early mitral diastolic velocity of 2 m/s or less or a mitral valve prosthesis-to-left ventricular outflow tract time-velocity integral ratio of less than 2.2. There was a significant (P < .001) negative correlation between the prosthesis performance index and prosthesis size. This negative correlation suggests that there is more efficient use of the in vitro geometric orifice area with smaller prostheses. 相似文献
32.
R H Miller M S Linet M L Van Natta L D McCaffrey R L Humphrey 《Archives of internal medicine》1987,147(9):1614-1617
Serum protein electrophoresis (SPEP) data obtained at diagnosis were available for 98 of 342 patients with chronic lymphocytic leukemia (CLL) identified in a population-based case-control epidemiologic study. Patients tested with SPEP at diagnosis were significantly younger, more likely to have lymphadenopathy, and more likely to have had their conditions diagnosed at a university hospital than those not tested. Four categories of electrophoretic patterns were identified: normal (N = 56), hypogammaglobulinemia (N = 28), hypergammaglobulinemia (N = 11), and monoclonal gammopathy (N = 3). A higher proportion of those with hypergammaglobulinemia were black, and patients with hypergammaglobulinemia and monoclonal gammopathy were more likely to die within the first year following diagnosis than patients in the other SPEP groups. No association was found, however, between SPEP pattern and a clinical staging classification for CLL. These findings suggest that SPEP may be a useful adjunct in categorizing possible subtypes of CLL and developing future clinical staging classifications. 相似文献
33.
Influence of Genetic Variation in the C-Reactive Protein Gene on the Inflammatory Response During and After Acute Coronary Ischemia 总被引:4,自引:0,他引:4
J. Suk Danik D. I. Chasman C. P. Cannon D. T. Miller R. Y. L. Zee P. Kozlowski D. J. Kwiatkowski P. M. Ridker 《Annals of human genetics》2006,70(6):705-716
The aim of this research was to assess whether common genetic variants within the C-reactive protein gene ( CRP ) are related to the degree of acute rise in plasma C-reactive protein (CRP) levels following an acute coronary syndrome (ACS). While polymorphisms within CRP are associated with basal CRP levels in healthy men and women, less is known about the relationship of such genetic variants and the degree of CRP rise during and after acute ischemia. Plasma CRP is associated with increased rates of recurrent coronary events. We evaluated seven common genetic variants within CRP and assessed their relationship to the degree of rise in CRP levels immediately following an acute coronary syndrome in 1827 European American patients. Variants in the putative promoter region, −757T > C and −286C > T > A, were associated with the highest CRP elevations after ACS. Patients with two copies of the A allele of SNP −286C > T > A had median CRP values of 76.6 mg/L, compared to 11.1 mg/L in patients with no copies of the rare variant (p-value <0.0001), post ACS. The lowest CRP values were found for patients with minor alleles of the exonic 1059G > C and the 3'untranslated region 1846G > A SNPs. For example, patients homozygous for the minor allele of 1059G > C had 71% lower median CRP values than those homozygous for the major allele [3.5 vs 12.0 mg/L, p < 0.0001]. These trends persisted in the chronic stable phase after ischemia had resolved, and after adjustment for infarct size by peak creatinine kinase levels and clinical status by Killip class. Assessment of CRP genetic variants identified patients with higher and lower CRP elevation after acute coronary syndrome. 相似文献
34.
35.
Donald L. Miller M.D. 《Cardiovascular and interventional radiology》1987,10(2):111-113
Ivalon (polyvinyl alcohol) is a commonly used embolic agent, generally considered to be permanent. In a patient with the carcinoid
syndrome, embolization of hepatic metastases with Ivalon failed to produce permanent occlusion, and recurrent tumor was supplied
by many of the same small arteries identified on the original arteriogram. Occasionally, Ivalon may have only a temporary
occlusive effect. A possible explanation for this phenomenon is proposed. 相似文献
36.
We describe five new cases of autosomal recessive distal dystrophy (Miyoshi myopathy) and emphasize the distinctive clinical and laboratory features of this unusual muscular dystrophy. Symptoms began at age 15 to 25, the gastrocnemius muscles were selectively involved, and creatine kinase was elevated more than 10 times normal. The EMG showed abundant brief motor units with numerous fibrillations. Dystrophic features without vacuoles were best seen in the biceps femoris muscle. Asymptomatic creatine kinase elevation was present years prior to the development of weakness. The disorder appears to be inherited in an autosomal recessive pattern. Miyoshi myopathy can be distinguished from other distal muscular dystrophies. We propose a new classification for the distal muscular dystrophies. 相似文献
37.
D. M. Reid I. Mackay S. Wilkinson C. Miller D. G. Schuette J. Compston C. Cooper E. Duncan N. Galwey R. Keen B. Langdahl A. McLellan H. Pols A. Uitterlinden J. O’Riordan J. A. H. Wass S. H. Ralston S. T. Bennett 《Osteoporosis international》2006,17(1):125-132
Osteoporosis is a common disease with a strong genetic component characterized by reduced bone mass and an increased risk of fragility fractures. Bone mineral density (BMD) is the most important determinant of osteoporotic fracture risk, but the genes responsible for BMD regulation and fracture are incompletely defined. To enable multi-center studies to examine the genetic influences on BMD there is a requirement to standardize measurements across different manufacturers of bone densitometers, different versions of machines and different normative ranges. This paper describes a method developed to allow near-identical subjects with low age-adjusted BMD (based on Z-scores) to be recruited in 17 centers using 27 different densitometers. Cross-calibration was based on measurements using a European spine phantom circulated to all centers and measured ten times on each individual machine. From theses values an individual exponential curve, based on nominal versus observed BMD, was derived for each machine. As expected, there were large and significant variations in nominal BMD values, not only between scanners from different manufacturers but also between different versions of scanners from the same manufacturer. Hologic scanners tended to underestimate the nominal BMD, while Lunar scanners overestimated the value. Norland scanners gave mixed values over estimating BMD at the lower nominal value (0.5 g/cm2) while underestimating the value at the higher value (1.5 g/cm2). The validity of the exponential equations was tested using hip and spine measurements on 991 non-proband women from a familial osteoporosis study (FAMOS). After cross-calibration there was a considerable reduction in variation between machines. This observation, coupled with the absence of a similar reduction in variation attributable to a linear regression on age, demonstrated the validity of the cross-calibration approach. Use of the cross-calibration curves along with a standard normative range (in the case of this study, the Hologic normative range) allowed age-specific Z-scores to be used as an inclusion criterion in this genetic study, a method that will be useful for other trials where age-specific BMD inclusion criteria are required. 相似文献
38.
Brain and spinal cord hemorrhage in long-term survivors of malignant pediatric brain tumors: a possible late effect of therapy 总被引:1,自引:0,他引:1
Three children with malignant primary CNS tumors treated with craniospinal radiotherapy developed intraparenchymal hemorrhages a median of 5 years following therapy in sites distant from the primary tumor. Radical surgical procedures disclosed fresh and old hematoma, gliosis, and necrosis in all 3 patients and an aggregation of abnormal microscopic blood vessels in two. No tumor was found. All 3 patients remain in long-term (greater than 10 years) continuous remission. 相似文献
39.
40.
Lumbar spondylolysis and spondylolisthesis in college football players. A prospective study 总被引:5,自引:0,他引:5
A prospective study was done on Indiana University freshman football players to determine if the incidence of lumbar spondylolysis and spondylolisthesis followed the pattern of previous studies. Using x-ray film evaluation, 145 freshman players were followed through their careers from 1978 to 1983. As in previous studies, a higher percentage (15.2%) of the defect was found than exists in the general population. However, only 2.4% of these players developed the problem in college, a much lower figure than previously found. Affected team members played a variety of positions. In addition to spondylolysis, some other problems, such as spina bifida occulta, were found. Theories on the cause of spondylolysis and spondylolisthesis are reviewed, and preventive suggestions such as more careful training and weight lifting are presented. 相似文献