全文获取类型
收费全文 | 1091篇 |
免费 | 81篇 |
国内免费 | 63篇 |
专业分类
耳鼻咽喉 | 6篇 |
儿科学 | 48篇 |
妇产科学 | 13篇 |
基础医学 | 116篇 |
口腔科学 | 32篇 |
临床医学 | 103篇 |
内科学 | 252篇 |
皮肤病学 | 27篇 |
神经病学 | 26篇 |
特种医学 | 257篇 |
外科学 | 51篇 |
综合类 | 61篇 |
预防医学 | 83篇 |
眼科学 | 7篇 |
药学 | 125篇 |
肿瘤学 | 28篇 |
出版年
2021年 | 12篇 |
2020年 | 8篇 |
2019年 | 4篇 |
2018年 | 10篇 |
2017年 | 11篇 |
2016年 | 18篇 |
2015年 | 21篇 |
2014年 | 24篇 |
2013年 | 24篇 |
2012年 | 18篇 |
2011年 | 19篇 |
2010年 | 30篇 |
2009年 | 33篇 |
2008年 | 24篇 |
2007年 | 53篇 |
2006年 | 27篇 |
2005年 | 43篇 |
2004年 | 22篇 |
2003年 | 25篇 |
2002年 | 17篇 |
2001年 | 31篇 |
2000年 | 23篇 |
1999年 | 28篇 |
1998年 | 56篇 |
1997年 | 67篇 |
1996年 | 57篇 |
1995年 | 58篇 |
1994年 | 35篇 |
1993年 | 43篇 |
1992年 | 15篇 |
1991年 | 22篇 |
1990年 | 23篇 |
1989年 | 48篇 |
1988年 | 38篇 |
1987年 | 35篇 |
1986年 | 17篇 |
1985年 | 26篇 |
1984年 | 12篇 |
1983年 | 7篇 |
1982年 | 15篇 |
1981年 | 18篇 |
1980年 | 19篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1977年 | 14篇 |
1976年 | 12篇 |
1975年 | 11篇 |
1974年 | 5篇 |
1973年 | 6篇 |
1969年 | 4篇 |
排序方式: 共有1235条查询结果,搜索用时 15 毫秒
81.
J Punnose MD DM TM Yahya MD JS Premchandran MD HF Ahmed FRCP 《International journal of clinical practice》1997,51(7):468-470
We describe two type 2 diabetic patients with unilateral emphysematous pyelonephritis who responded to medical treatment alone. Escherichia coli was isolated in both patients. The presence of gas was confirmed early by ultrasound and CT scan of abdomen. Following treatment, good functional recovery was demonstrable in the affected kidneys by isotope renogram. We stress the need for early diagnosis of this condition and aggressive treatment with broad spectrum antibiotics. 相似文献
82.
83.
A multilaboratory study was conducted to develop a system for standardizing alanine aminotransferase (ALT) acceptability criteria ("cutoffs") for donated blood. Without standardized cutoffs, each laboratory must develop its own cutoff, and this may not make optimal use of ALT testing to reduce transmission of non-A, non-B hepatitis (NANB). Defining an ALT acceptability criterion in absolute terms is necessary because relative cutoffs based on local donor populations may be affected by the prevalence of NANB in each community. This study involved 16 laboratories using 23 different analytic systems. The ALT results of the analysis of a plasma reference sample could be used to translate mathematically a single, absolute cutoff to units applicable to each analytic system. The distribution of ALT results in 1.4 million donations from across the country was established; basing the cutoff on this sample avoids the problems inherent in using a local donor base to establish a cutoff. We propose the implementation of a system to standardize ALT acceptability criteria to an activity level defined by analysis of a nationwide donor sample. 相似文献
84.
CJ Chantry JS Cervia MD Hughes C Alvero J Hodge P Borum J Moye Jr. for the PACTG Team 《HIV medicine》2010,11(9):573-583
Objectives
The aim of the study was to describe growth and body composition changes in HIV‐positive children after they had initiated or changed antiretroviral therapy (ART) and to correlate these with viral, immune and treatment parameters.Methods
Ninety‐seven prepubertal HIV‐positive children were observed over 48 weeks upon beginning or changing ART. Anthropometry and bioelectrical impedance analysis results were compared with results from the National Health and Nutrition Examination Survey 1999–2002 (NHANES) to generate z‐scores and with results for HIV‐exposed, uninfected children from the Women and Infants Transmission Study (WITS). Multivariate analysis was used to evaluate associations between growth and body composition and disease parameters.Results
All baseline lean and fat mass measures were below those of controls from NHANES. Weight, height and fat free mass (FFM) index (FFM/height2) z‐scores increased over time (P=0.004, 0.037 and 0.027, respectively) and the waist:height ratio z‐score decreased (P=0.045), but body mass index and per cent body fat z‐scores did not change. Measures did not increase more than in uninfected WITS controls. In multivariate analysis, baseline height, mid‐thigh circumference and FFM z‐scores related to CD4 percentage (P=0.029, P=0.008 and 0.020, respectively) and change in FFM and FFM index z‐scores to CD4 percentage increase (P=0.010 and 0.011, respectively). Compared with WITS controls, baseline differences in height and mid‐thigh muscle circumference were also associated with CD4 percentage. Case–control differences in change in both subscapular skinfold (SSF) thickness and the SSF:triceps skinfold ratio were inversely associated with viral suppression. No measures related to ART class(es) at baseline or over time.Conclusions
In these HIV‐positive children, beginning or changing ART was associated with improved growth and lean body mass (LBM), as indicated by FFM index. Height and LBM related to CD4 percentage at baseline and over time. Altered fat distribution and greater central adiposity were associated with detectable virus but not ART class(es) received. 相似文献85.
WH Belloso LC Orellana B Grinsztejn JS Madero A La Rosa VG Veloso J Sanchez R Ismerio Moreira B Crabtree‐Ramirez O Garcia Messina MB Lasala J Peinado MH Losso 《HIV medicine》2010,11(9):554-564
Objective
Acquired immune deficiency appears to be associated with serious non‐AIDS (SNA)‐defining conditions such as cardiovascular disease, liver and renal insufficiency and non‐AIDS‐related malignancies. We analysed the incidence of, and factors associated with, several SNA events in the LATINA retrospective cohort.Materials and methods
Cases of SNA events were recorded among cohort patients. Three controls were selected for each case from cohort members at risk. Conditional logistic models were fitted to estimate the effect of traditional risk factors as well as HIV‐associated factors on non‐AIDS‐defining conditions.Results
Among 6007 patients in follow‐up, 130 had an SNA event (0.86 events/100 person‐years of follow‐up) and were defined as cases (40 with cardiovascular events, 54 with serious liver failure, 35 with non‐AIDS‐defining malignancies and two with renal insufficiency). Risk factors such as diabetes, hepatitis B and C virus coinfections and alcohol abuse showed an association with events, as expected. The last recorded CD4 T‐cell count prior to index date (P=0.0056, with an average difference of more than 100 cells/μL) and area under the CD4 cell curve in the year previous to index date (P=0.0081) were significantly lower in cases than in controls. CD4 cell count at index date was significantly associated with the outcome after adjusting for risk factors.Conclusions
The incidence and type of SNA events found in this Latin American cohort are similar to those reported in other regions. We found a significant association between immune deficiency and the risk of SNA events, even in patients under antiretroviral treatment. 相似文献86.
87.
A. Y. Chu J. Coresh D. E. Arking J. S. Pankow G. F. Tomaselli A. Chakravarti W. S. Post P. H. Spooner E. Boerwinkle W. H. L. Kao 《Diabetologia》2010,53(3):510-516
Aims/hypothesis
To validate the reported association between rs10494366 in NOS1AP (the gene encoding nitric oxide synthase-1 adaptor protein) and the incidence of type 2 diabetes in calcium channel blocker (CCB) users and to identify additional NOS1AP variants associated with type 2 diabetes risk. 相似文献88.
89.
James F Pankow Karen H Watanabe Patricia L Toccalino Wentai Luo Donald F Austin 《Cancer epidemiology, biomarkers & prevention》2007,16(3):584-592
Toxicant deliveries (by machine smoking) are compiled and associated cancer risks are calculated for 13 carcinogens from 26 brands of conventional cigarettes categorized as "regular" (R), "light" (Lt), or "ultralight" (ULt), and for a reference cigarette. Eight "potentially reduced exposure product" (PREP) cigarettes are also considered. Because agency-to-agency differences exist in the cancer slope factor (CSF) values adopted for some carcinogens, two CSF sets were used in the calculations: set I [U.S. Environmental Protection Agency (EPA)-accepted values plus California EPA-accepted values as needed to fill data gaps] and set II (vice versa). The potential effects of human smoking patterns on cigarette deliveries are considered. Acetaldehyde, 1,3-butadiene, and acrylonitrile are associated with the largest calculated cancer risks for all 26 brands of conventional cigarettes. The calculated risks are proportional to the smoking dose z (pack-years). Using CSF set I and z = 1 pack-year (7,300 cigarettes), the calculated brand-average incremental lifetime cancer risk ILCR(1)(acetaldehyde) values are R, 6 x 10(-5); Lt, 5 x 10(-5); and ULt, 3 x 10(-5) (cf. typical U.S. EPA risk benchmark of 10(-6)). These values are similar, especially given the tendency of smokers to "compensate" when smoking Lt and ULt cigarettes. ILCR(1)(subSigma-lung) is the brand-average per pack-year subtotal risk for the measured human lung carcinogens. Using CSF set I, the ILCR(1)(subSigma-lung) values for R, Lt, and ULt cigarettes account for 相似文献
90.
Alastair JS Webb Amy Lawson Linxin Li Sara Mazzucco Peter M Rothwell for the Oxford Vascular Study Phenotyped Cohort 《Journal of cerebral blood flow and metabolism》2021,41(6):1463
Cerebral arterial pulsatility is strongly associated with cerebral small vessel disease and lacunar stroke yet its dependence on central versus local haemodynamic processes is unclear. In a population-based study of patients on best medical managment, 4–6 weeks after a TIA or non-disabling stroke, arterial stiffness and aortic systolic, diastolic and pulse pressures were measured (Sphygmocor). Middle cerebral artery peak and trough flow velocities and Gosling’s pulsatility index were measured by transcranial ultrasound. In 981 participants, aortic and cerebral pulsatility rose strongly with age in both sexes, but aortic diastolic pressure fell more with age in men whilst cerebral trough velocity fell more in women. There was no significant association between aortic systolic or diastolic blood pressure with cerebral peak or trough flow velocity but aortic pulse pressure explained 37% of the variance in cerebral arterial pulsatility, before adjustment, whilst 49% of the variance was explained by aortic pulse pressure, arterial stiffness, age, gender and cardiovascular risk factors. Furthermore, arterial stiffness partially mediated the relationship between aortic and cerebral pulsatility. Overall, absolute aortic pressures and cerebral blood flow velocity were poorly correlated but aortic and cerebral pulsatility were strongly related, suggesting a key role for transmission of aortic pulsatility to the brain. 相似文献