全文获取类型
收费全文 | 3374篇 |
免费 | 346篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 17篇 |
儿科学 | 131篇 |
妇产科学 | 145篇 |
基础医学 | 392篇 |
口腔科学 | 23篇 |
临床医学 | 459篇 |
内科学 | 508篇 |
皮肤病学 | 190篇 |
神经病学 | 247篇 |
特种医学 | 96篇 |
外科学 | 647篇 |
综合类 | 78篇 |
一般理论 | 1篇 |
预防医学 | 365篇 |
眼科学 | 35篇 |
药学 | 248篇 |
中国医学 | 11篇 |
肿瘤学 | 130篇 |
出版年
2023年 | 18篇 |
2022年 | 19篇 |
2021年 | 58篇 |
2020年 | 32篇 |
2019年 | 53篇 |
2018年 | 65篇 |
2017年 | 70篇 |
2016年 | 55篇 |
2015年 | 65篇 |
2014年 | 96篇 |
2013年 | 121篇 |
2012年 | 178篇 |
2011年 | 191篇 |
2010年 | 97篇 |
2009年 | 93篇 |
2008年 | 160篇 |
2007年 | 189篇 |
2006年 | 161篇 |
2005年 | 191篇 |
2004年 | 163篇 |
2003年 | 142篇 |
2002年 | 136篇 |
2001年 | 113篇 |
2000年 | 100篇 |
1999年 | 113篇 |
1998年 | 50篇 |
1997年 | 40篇 |
1996年 | 26篇 |
1995年 | 40篇 |
1994年 | 32篇 |
1993年 | 30篇 |
1992年 | 76篇 |
1991年 | 79篇 |
1990年 | 62篇 |
1989年 | 60篇 |
1988年 | 34篇 |
1987年 | 55篇 |
1986年 | 45篇 |
1985年 | 52篇 |
1984年 | 35篇 |
1983年 | 31篇 |
1982年 | 20篇 |
1979年 | 20篇 |
1978年 | 18篇 |
1976年 | 25篇 |
1975年 | 15篇 |
1974年 | 26篇 |
1973年 | 19篇 |
1972年 | 16篇 |
1970年 | 15篇 |
排序方式: 共有3723条查询结果,搜索用时 15 毫秒
11.
12.
Russell S. Kirby 《分娩》2004,31(2):148-151
Commentary on: Zhang J, Yancey MK, Henderson CE. U.S. national trends in labor induction, 1989–1998. J Reprod Med 2002;47:120–124. MacDorman MF, Mathews TJ, Martin JA, Malloy MH. Trends and characteristics of induced labour in the United States, 1989–98. Paediatr Perinat Epidemiol 2002;16:263–273. Kozak LJ, Weeks JD. U.S. trends in obstetric procedures, 1990–2000. Birth 2002;29:157–161. Abstract: Three recent studies examined the national trend in labor induction in the United States. All show a doubling in the rate of induction during the 1990s, although vital statistics data show a consistently higher trend than that obtained from national hospital discharge data. Neither data source adequately documents the full range of indications for induction, its timing, hospital staffing considerations, and other factors that may play a role. Although rates of induction of labor may be leveling off, despite a lack of scientific evidence for its widespread use, rates are likely to remain at current levels for the next few years. 相似文献
13.
The University Hospital Nurse Extender Model using patient care technicians is a long-term strategy to maintain quality patient care. The authors present an overview and conceptual framework of the model. In future papers in this four-part series, the authors will discuss the implementation and evaluation of the model and describe six lessons learned during the implementation process. This information will be useful to any nursing administrator planning to implement a change in the way patient care is delivered. 相似文献
14.
15.
This study was designed to examine serum lipid profile and blood pressure in relation to age and sexual maturity. Written informed consent to participate was obtained from 42% of the eligible population of two Devon communities. The blood pressure of 343 boys and 336 girls, aged 11-16 years, was recorded and sufficient blood for analysis was obtained from 320 boys and 301 girls. Of these, sexual maturity of 221 boys and 209 girls was visually assessed using the indices developed by Tanner. In girls there was a significant (p less than 0.05) correlation between age and serum triglyceride level (r = 0.16) and in boys both serum cholesterol and HDL-cholesterol were significantly (p less than 0.01) and negatively correlated with age (r = -0.25 and -0.18 respectively). Girls had significantly higher (p less than 0.05) levels of HDL-cholesterol than boys but neither sex demonstrated significant changes (p greater than 0.05) in serum lipids or lipoproteins with sexual maturity. No significant differences (p greater than 0.05) were detected between the mean diastolic blood pressures of boys and girls but older boys had significantly higher (p less than 0.05) systolic blood pressures than similarly aged girls. Age was positively and significantly correlated (p less than 0.01) with blood pressure in both boys (systolic, r = 0.49; diastolic, r = 0.30) and girls (systolic, r = 0.28; diastolic, r = 0.29). More mature children were demonstrated to have both higher systolic and diastolic blood pressures than less mature children (p less than 0.05) but when allowance was made for school year group through analysis of co-variance the relationship for diastolic blood pressure in boys no longer remained significant. Blood pressures observed in this study do not raise general cause for concern but the data indicate that unfavourable serum lipid and lipoprotein profiles are common. 相似文献
16.
17.
PURPOSE: Prostacyclin, a potent inhibitor of platelet function and vasodilator, has been used to treat peripheral vascular disease. The aim of this study was to monitor the thrombotic status of patients treated by infusion of a stable prostacyclin analogue, iloprost. PATIENTS AND METHODS: Thirteen patients with peripheral vascular disease underwent iloprost infusion for 3 days (8 hours each day) in a dose ranging from 0.5 to 2 ng/kg/minute. Variable parameters of thrombosis such as platelet reactivity (shear-induced hemostatic plug formation and thrombus formation on a collagen fiber), coagulation, and spontaneous thrombolysis (dislodgment of hemostatic plugs) were measured from non-anticoagulated blood samples by hemostatometry immediately before and 1 hour after the infusion and on the last day, 4 hours after initiation of the infusion. RESULTS: Analysis of data from all patients 1 hour after the infusion showed no changes in platelet reactivity and spontaneous thrombolysis, but coagulation was significantly enhanced. In four patients, significant platelet hyperreactivity was observed after the infusion. Four of the five patients tested while undergoing iloprost infusion showed an enhanced thrombotic reaction and markedly enhanced coagulation. Iloprost employed in vitro in a concentration that corresponds to the therapeutic peak blood level caused no inhibition of platelet function but significantly enhanced coagulation. The threshold in vitro iloprost concentration at which anti-platelet effect and increased spontaneous thrombolysis were observed was twice that of the therapeutic blood level. CONCLUSIONS: These findings challenge the view that antagonism of platelet function is an important factor of iloprost therapy. Furthermore, platelet hyperreactivity in some patients and markedly enhanced coagulation during and after infusion of iloprost in general, represent a risk of thromboembolism, especially as patients are already in a prethrombotic condition. 相似文献
18.
Tree sampling helped locate a subterranean flow of tritiated water from a low-level radioactive waste disposal site that had not been detected by well water monitoring alone. Deciduous trees growing in a natural forest on the hillsides downslope from the site were sampled for the presence of tritiated water in sap of maple trees and in leaf water extracted from oak and hickory trees. Elevated concentrations of 3H were detected in the leaf water extracted from several trees located 50 m downslope from the western boundary of the fenced exclusion zone. A 3-m-deep well drilled near these trees indicated that the source of tritiated water was a narrow zone of subterranean flow. 相似文献
19.
M A Brewster R S Kirby C R Feild C M Cunniff 《Public health reports (Washington, D.C. : 1974)》1992,107(3):290-296
Planning of service delivery systems for children with special health care needs would be enhanced by knowledge of numbers of cases anticipated in defined geographic areas. A method is described for predicting numbers of children who will likely have mental retardation sufficient to require special education services, based on the birth prevalence of birth defects and clinicians' estimates of the likelihood of mental retardation associated with each specific birth defect. This method is applied to the 1980-82 birth cohort of a 28-county area of south and central Arkansas, and it is compared with special education enrollment data for children ages 6 to 8 in academic year 1988-89. According to this estimate, children with birth defects may account for 32 to 56 percent of the cases of mental retardation among 6- to 8-year-olds reported by the public schools. 相似文献
20.
Daniel L. Rubin Karen L. Falk Malcolm J. Sperling Michael Ross Sanjay Saini Barry Rothman Frank Shellock Elias Zerhouni David Stark Eric K. Outwater Udo Schmiedl Louis C. Kirby Judith Chezmar Terry Coates Miles Chang Jeffery M. Silverman Neil Rofsky Keith Burnett Julie Engel Stuart W. Young 《Journal of magnetic resonance imaging : JMRI》1997,7(5):865-872
The purpose of this study was to assess the effectiveness and safety of Gadolite Oral Suspension as a gastrointestinal (GI) contrast agent for MRI in a phase II and two phase III multicenter clinical trials. Gadolite was administered to 306 patients with known or suspected abdominal and/or pelvic disease. MRI with T1- and T2-weighted sequences was performed before and after ingestion. Efficacy was evaluated by having two masked readers rate the certainty of their MR diagnosis (0 = uncertain, 1 = probable, 2 = definite) on randomly presented pre- and post-Gadolite Oral Suspension enhanced images. Principal investigators also evaluated the images and established the final diagnosis. Vital signs, clinical chemistries, and adverse events were documented. Blood and urine samples were analyzed for gadolinium content to determine whether Gadolite Oral Suspension was absorbed systemically. Certainty in MR diagnosis increased significantly (P < .001) for both blinded readers between pre- and post-Gadolite images (.49–1.18 for reader 1; .46–1.53 for reader 2). Sensitivity, specificity, and accuracy also increased for both masked readers. No gadolinium was detected in blood or urine samples. There were no serious adverse events and no apparent drug-related trends in mean vital signs or laboratory values. Gadolite is a highly effective, safe, and well tolerated contrast agent for clinical use with MRI. 相似文献