全文获取类型
收费全文 | 686篇 |
免费 | 33篇 |
国内免费 | 16篇 |
专业分类
耳鼻咽喉 | 8篇 |
儿科学 | 19篇 |
妇产科学 | 3篇 |
基础医学 | 60篇 |
口腔科学 | 5篇 |
临床医学 | 67篇 |
内科学 | 145篇 |
皮肤病学 | 10篇 |
神经病学 | 74篇 |
特种医学 | 112篇 |
外科学 | 60篇 |
综合类 | 13篇 |
预防医学 | 36篇 |
眼科学 | 2篇 |
药学 | 98篇 |
肿瘤学 | 23篇 |
出版年
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 8篇 |
2016年 | 7篇 |
2015年 | 13篇 |
2014年 | 14篇 |
2013年 | 15篇 |
2012年 | 20篇 |
2011年 | 25篇 |
2010年 | 13篇 |
2009年 | 13篇 |
2008年 | 18篇 |
2007年 | 36篇 |
2006年 | 19篇 |
2005年 | 22篇 |
2004年 | 21篇 |
2003年 | 24篇 |
2002年 | 21篇 |
2001年 | 19篇 |
2000年 | 21篇 |
1999年 | 13篇 |
1998年 | 15篇 |
1997年 | 22篇 |
1996年 | 24篇 |
1995年 | 28篇 |
1994年 | 16篇 |
1993年 | 17篇 |
1992年 | 9篇 |
1991年 | 10篇 |
1990年 | 15篇 |
1989年 | 25篇 |
1988年 | 21篇 |
1987年 | 15篇 |
1986年 | 10篇 |
1985年 | 12篇 |
1984年 | 8篇 |
1983年 | 11篇 |
1982年 | 12篇 |
1981年 | 11篇 |
1979年 | 9篇 |
1978年 | 8篇 |
1977年 | 5篇 |
1976年 | 12篇 |
1975年 | 10篇 |
1974年 | 6篇 |
1971年 | 4篇 |
1970年 | 5篇 |
1969年 | 7篇 |
排序方式: 共有735条查询结果,搜索用时 299 毫秒
71.
72.
Flexible tantalum stents implanted in aortas and iliac arteries: effects in normal canines 总被引:2,自引:0,他引:2
Barth KH; Virmani R; Strecker EP; Savin MA; Lindisch D; Matsumoto AH; Teitelbaum GP 《Radiology》1990,175(1):91-96
Vascular endoprostheses made of knitted tantalum wire and expanded over angioplasty balloons were placed into aortas or iliac arteries of 14 normal dogs. Twelve stents were placed into the infrarenal abdominal aorta and two stents in the left common iliac arteries by the left carotid artery approach. To firmly expand the stent against the vascular wall, nominal stent sizes 0.5-1.0 mm larger than the measured arterial diameter were required. Arteriography performed at specified follow-up intervals showed no evidence of thrombi or emboli; all side branches (lumbar arteries) covered by the stents remained patent. Vascular diameter decreased minimally at 8 and 26 weeks, associated with histopathologic evidence of neointimal buildup. This buildup was highest at 8 weeks (mean, 313 microns) and was slightly less at 26 weeks (mean, 223 microns). Almost complete coverage by endothelium was seen as early as 3 weeks. It is concluded that the flexible tantalum wire stents are well tolerated by the arterial wall and become quickly endothelialized. No excessive neointimal buildup was observed during the 6-month study. 相似文献
73.
Chondromalacia patellae: assessment with MR imaging 总被引:10,自引:0,他引:10
Yulish BS; Montanez J; Goodfellow DB; Bryan PJ; Mulopulos GP; Modic MT 《Radiology》1987,164(3):763-766
Magnetic resonance (MR) images of the posterior patellar hyaline articular cartilage were obtained in 23 subjects to determine if MR imaging could accurately demonstrate the patellar cartilage. Arthroscopy was used as the standard of reference. Three subjects were asymptomatic volunteers. In the remaining 20 who had patellofemoral pain, arthroscopy was performed before MR imaging in seven and afterward in 12; one did not undergo arthroscopy. MR imaging showed focal areas of swelling of the patellar cartilage, focal hypointensity, surface irregularity, areas of thinning, and areas of cartilage loss with exposure of subchondral bone. The surgical findings agreed with those from MR images in all seven patients who underwent arthroscopy before MR imaging and in ten of the 12 who underwent surgery afterward. MR imaging is an accurate means of examining the posterior patellar cartilage and should be considered as an alternative to diagnostic arthroscopy when chondromalacia patellae is suspected. 相似文献
74.
Kominski G Andersen R Bastani R Gould R Hackman C Huang D Jarvik L Maxwell A Moye J Olsen E Rohrbaugh R Rosansky J Taylor S Van Stone W 《Medical care》2001,39(5):500-512
BACKGROUND: The Unified Psychogeriatric Biopsychosocial Evaluation and Treatment (UPBEAT) program provides individualized interdisciplinary mental health treatment and care coordination to elderly veterans whose comorbid depression, anxiety, or alcohol abuse may result in overuse of inpatient services and underuse of outpatient services. OBJECTIVES: To determine whether proactive screening of hospitalized patients can identify unrecognized comorbid psychiatric conditions and whether comprehensive assessment and psychogeriatric intervention can improve care while reducing inpatient use. DESIGN: Randomized trial. SUBJECTS: Veterans aged 60 and older hospitalized for nonpsychiatric medical or surgical treatment in 9 VA sites (UPBEAT, 814; usual care, 873). MEASURES: The Mental Health Inventory (MHI) anxiety and depression subscales, the Alcohol Use Disorder Identification Test (AUDIT) scores, RAND 36-Item Health Survey Short Form (SF-36), inpatient days and costs, ambulatory care clinic stops and costs, and mortality and readmission rates. RESULTS: Mental health and general health status scores improved equally from baseline to 12-month follow-up in both groups. UPBEAT increased outpatient costs by $1,171 (P <0.001) per patient, but lowered inpatient costs by $3,027 (P = 0.017), for an overall savings of $1,856 (P = 0.156). Inpatient savings were attributable to fewer bed days of care (3.30 days; P = 0.016) rather than fewer admissions. Patients with 1 or more pre-enrollment and postenrollment hospitalizations had the greatest overall savings ($6,015; P = 0.069). CONCLUSIONS: UPBEAT appears to accelerate the transition from inpatient to outpatient care for acute nonpsychiatric admissions. Care coordination and increased access to ambulatory psychiatric services produces similar improvement in mental health and general health status as usual care. 相似文献
75.
目的:了解丹参酮ⅡA对神经祖细胞系C17.2的保护作用,探讨其可能的作用机制。方法:本实验于2005年起在广州血液中心器官移植配型中心实验室进行。C17.2祖细胞系由澳大利亚新南威尔士大学解剖教研室David Walsh博士惠赠。将C17.2细胞以1×109L-1的密度接种,用含10%胎牛血清IMDM,37℃、体积分数为0.05CO2、饱和湿度的CO2培养箱培养,接近融合的C17.2细胞用含0.1mmol/LEDTA的胰酶室温消化,按1∶3的比例传代。C17.2细胞以5×107L-1的密度接种于96孔板或25cm2的培养瓶中,用含10%胎牛血清IMDM培养过夜后,加入含4g/L AAPH(水溶性偶氮引发剂2,2'-偶氮二(2-脒基丙烷)二盐酸盐)无血清的IMDM培养基培养建立神经细胞凋亡模型。C17.2细胞以5×103/孔的密度接种于96孔板中,用含10%胎牛血清IMDM培养过夜后,加入含4g/LAAPH无血清的IMDM培养基培养。对照组不加入丹参酮ⅡA,实验组分别加入0.02,0.05,0.1,0.2mg/L丹参酮ⅡA培养8h,噻唑蓝法检测细胞活性:细胞活性的相对值=(实验组吸光度值/对照组吸光度值)×100%,流式细胞仪检测细胞凋亡。结果:①AAPH处理8h后,C17.2细胞被过氧化损害,大多数细胞失去正常的形态,细胞呈圆形,脱落。加入丹参酮ⅡA后,细胞形态基本保持正常,少数细胞呈圆形。②C17.2细胞在IMDM的培养液中,细胞数量是含4g/L AAPH无血清的IMDM培养基条件下的2.5~3倍。浓度为0.02,0.05,0.1mg/L的丹参酮ⅡA对C17.2细胞有保护作用,质量浓度大于0.2mg/L丹参酮ⅡA对C17.2细胞保护作用降低。③AAPH作用前大部分C17.2细胞的线粒体完整,有少量的早期凋亡细胞和凋亡细胞,AAPH作用后凋亡细胞总数、凋亡细胞明显增加。丹参酮ⅡA处理组可以明显减少早期凋亡细胞。结论:在体外丹参酮ⅡA对神经细胞具有抗凋亡的作用,可以保护神经细胞。 相似文献
76.
Host and environmental effects on plasma apolipoprotein B 总被引:2,自引:0,他引:2
Gail Pairitz Jarvik Ellen Wijsman Ruth E. Little John J. Albers Arno G. Motulsky John D. Brunzell 《International Journal of Clinical & Laboratory Research》1993,23(1-4):215-220
Summary In this study, levels of apo B in an unselected sample of 487 middle-aged Caucasian spouses of patients and spouses of the
patients’ relatives are described. In males, apo B levels increased with age until the 7th decade, then declined; apo B levels
in females, which were lower than in males, increased linearly with age across the entire life-span. Height and weight, smoking,
and presence of noninsulin-dependent diabetes mellitus significantly influenced age- and gender-adjusted apo B levels in this
sample, whereas use of alcohol, diuretics, β-blockers, or insulin did not. Age, gender, height, weight, smoking, and noninsulin-dependent
diabetes mellitus account for 21% of the total variation in apo B levels in this sample. 相似文献
77.
78.
Geyer M Howell-Jones R Cunningham R McNulty C;Health Protection Agency GP Microbiology Laboratory Use Group 《British journal of biomedical science》2011,68(4):174-180
Otitis externa is a ubiquitous inflammatory disease; although it arises most commonly from an infection, there is no consensus in the UK for the reporting of ear swab culture results. This study aims to review current microbiology laboratory reporting of ear swab specimens to primary care and reach an evidence-based consensus for a reporting policy. Fifty consecutive ear swab reports were reviewed from each of 12 laboratories in the South West region to determine and discuss reporting practice. The Health Protection Agency (HPA) GP Microbiology Laboratory Use Group reviewed the underlying evidence and worked towards a consensus of expert microbiology opinion for laboratory reporting of ear swab results using a modified version of the Delphi technique. A total of 487 reports from primary care were reviewed (54% female; 46% male). Cultures most commonly yielded Pseudomonas species (36%), Staphylococcus species (21%), Streptococcus species (15%) and fungi (11%). Five reporting policies were agreed: Policy 1: Common pathogens such as group A beta-haemolytic streptococci, Streptococcus pneumoniae, Staphylococcus aureus - Always reported by name with antibiotic susceptibilities. Policy 2: Pseudomonas species - Always reported, but antibiotic susceptibilities only reported in severe disease. Policy 3: Aspergillus, Candida, coliforms and Proteus species, as well as non-group A streptococci and anaerobes - Only reported if moderate numbers of colonies and it is the predominant organism present; if appropriate report antibiotic susceptibilities. Policy 4: Coagulase-negative staphylococci, diphtheroids and enterococci - Not reported by name; generic terms used and antibiotic susceptibilities not reported. Policy 5: When antibiotic susceptibilities reported these must include susceptibility to a topical antibiotic. It is suggested that laboratories should consider adopting this evidence-based reporting consensus for ear swab culture results from primary care patients with otitis externa. 相似文献
79.
Saam T Yuan C Chu B Takaya N Underhill H Cai J Tran N Polissar NL Neradilek B Jarvik GP Isaac C Garden GA Maravilla KR Hashimoto B Hatsukami TS 《Atherosclerosis》2007,194(2):e34-e42
The purpose of this in vivo MRI study was to quantify changes in atherosclerotic plaque morphology prospectively and to identify factors that may alter the rate of progression in plaque burden. Sixty-eight asymptomatic subjects with >or=50% stenosis, underwent serial carotid MRI examinations over an 18-month period. Clinical risk factors for atherosclerosis, and medications were documented prospectively. The wall and total vessel areas, matched across time-points, were measured from cross-sectional images. The normalized wall index (NWI=wall area/total vessel area), as a marker of disease severity, was documented at baseline and at 18 months. Multiple regression analysis was used to correlate risk factors and morphological features of the plaque with the rate of progression/regression. On average, the wall area increased by 2.2% per year (P=0.001). Multiple regression analysis demonstrated that statin therapy (P=0.01) and a normalized wall index >0.64 (P=0.001) were associated with a significantly reduced rate of progression in mean wall area. All other documented risk factors were not significantly associated with changes in wall area. Findings from this study suggest that increased normalized wall index and the use of statin therapy are associated with reduced rates of plaque progression amongst individuals with advanced, asymptomatic carotid atherosclerosis. 相似文献
80.
Memantine and HIV-associated cognitive impairment: a neuropsychological and proton magnetic resonance spectroscopy study 总被引:2,自引:0,他引:2
Schifitto G Navia BA Yiannoutsos CT Marra CM Chang L Ernst T Jarvik JG Miller EN Singer EJ Ellis RJ Kolson DL Simpson D Nath A Berger J Shriver SL Millar LL Colquhoun D Lenkinski R Gonzalez RG Lipton SA;Adult AIDS Clinical Trial Group 《AIDS (London, England)》2007,21(14):1877-1886
OBJECTIVE: To assess the safety and efficacy of memantine, an uncompetitive antagonist of the N-methyl-D-aspartate receptor as treatment of HIV-associated cognitive impairment. METHODS: This was a Phase II randomized, double-blind, placebo-controlled, multicenter trial within the Adult AIDS Clinical Trials Group. One-hundred and forty HIV-infected adults with mild to severe AIDS dementia complex receiving stable antiretroviral therapy were enrolled. Memantine was initiated at 10 mg daily escalated to 40 mg daily, or up to the maximum tolerated dose and continued for 16 weeks (primary evaluation visit) followed by a 4-week washout period and re-evaluation at week 20. Changes in cognitive performance were measured as percent change from baseline to week 16 in the average of eight neuropsychological test scores (NPZ-8). Brain metabolism was measured by magnetic resonance spectroscopy in a subgroup of subjects. RESULTS: Sixty-one percent of subjects in the memantine group and 85% in the placebo group reached the 40 mg dose while the reported adverse experiences between the two groups were similar. There were no significant improvements in neuropsychological performance over 16 weeks; however, memantine was associated with a significant increase at week 16 in the N-acetyl aspartate to creatine ratio, in the frontal white matter (P = 0.040) and parietal cortex (P = 0.023). CONCLUSIONS: Memantine was safe and tolerated by HIV-infected subjects with cognitive impairment. Although we observed no significant differences in cognitive performance, the magnetic resonance spectroscopy data suggest that memantine may ameliorate neuronal metabolism, an important step to stabilizing or preventing neuronal injury. These results underscore the need for longer studies to assess the full potential of neuroprotective agents. 相似文献