全文获取类型
收费全文 | 2590660篇 |
免费 | 216527篇 |
国内免费 | 18117篇 |
专业分类
耳鼻咽喉 | 36250篇 |
儿科学 | 75508篇 |
妇产科学 | 67261篇 |
基础医学 | 359708篇 |
口腔科学 | 71265篇 |
临床医学 | 244355篇 |
内科学 | 503381篇 |
皮肤病学 | 50383篇 |
神经病学 | 212727篇 |
特种医学 | 103654篇 |
外国民族医学 | 982篇 |
外科学 | 384021篇 |
综合类 | 89283篇 |
现状与发展 | 49篇 |
一般理论 | 1019篇 |
预防医学 | 204512篇 |
眼科学 | 61647篇 |
药学 | 199725篇 |
168篇 | |
中国医学 | 15061篇 |
肿瘤学 | 144345篇 |
出版年
2021年 | 27075篇 |
2019年 | 24340篇 |
2018年 | 31662篇 |
2017年 | 25326篇 |
2016年 | 26767篇 |
2015年 | 32776篇 |
2014年 | 45451篇 |
2013年 | 61885篇 |
2012年 | 85027篇 |
2011年 | 90192篇 |
2010年 | 53502篇 |
2009年 | 49573篇 |
2008年 | 80377篇 |
2007年 | 84812篇 |
2006年 | 85355篇 |
2005年 | 83613篇 |
2004年 | 77183篇 |
2003年 | 73983篇 |
2002年 | 72269篇 |
2001年 | 116641篇 |
2000年 | 120961篇 |
1999年 | 103382篇 |
1998年 | 31145篇 |
1997年 | 28927篇 |
1996年 | 28005篇 |
1995年 | 27000篇 |
1994年 | 25223篇 |
1993年 | 22932篇 |
1992年 | 81046篇 |
1991年 | 77860篇 |
1990年 | 74806篇 |
1989年 | 71893篇 |
1988年 | 66755篇 |
1987年 | 65653篇 |
1986年 | 62009篇 |
1985年 | 58911篇 |
1984年 | 44549篇 |
1983年 | 37918篇 |
1982年 | 23031篇 |
1979年 | 41478篇 |
1978年 | 29082篇 |
1977年 | 24410篇 |
1976年 | 22896篇 |
1975年 | 24022篇 |
1974年 | 29718篇 |
1973年 | 28110篇 |
1972年 | 26276篇 |
1971年 | 24200篇 |
1970年 | 22797篇 |
1969年 | 21113篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
981.
982.
糖耐量试验对评价肝癌患者肝脏储备功能的价值 总被引:5,自引:0,他引:5
绝大多数肝细胞性肝癌患者合并肝硬变,为预测其对肝切除的耐受性,给正确选择切肝患者提供依据,作者对62例切肝者和49例未切肝者手术前后的糖耐量试验(OGTT)和肝组织病理学进行了对比研究。结果:术前OGTT曲地P型者切肝后恢复顺利;L型者对肝切的耐受性差,术后易发生肝功能衰竭等并发症,其肝硬化和蔼多为CⅢ或CⅣ级,曲线形态界于P和L型之间的I型患者29例用肝门区域血管阻断法切肝,并在阻断血管前使用预 相似文献
983.
J Grogan B H Nowicki T A Schmidt V M Haughton 《AJNR. American journal of neuroradiology》1997,18(7):1325
PURPOSETo study the relationship of lumbar facet joint tropism to degeneration of the cartilage and subcortical bone in the facet joints and the effect of tropism in intervertebral disk degeneration.METHODSThe orientation of 104 cadaveric lumbar facet joints with respect to sagittal plane was measured on CT scans, and the joints were classified as having no tropism, mild tropism, or severe tropism. On MR images, the severity of cartilage degeneration and bony sclerosis was measured. The correlation between tropism and degeneration was calculated, as was the relationship among age, spinal level, and degeneration.RESULTSWe identified four spinal levels with severe tropism, six with moderate tropism, and 94 without tropism. Cartilage degeneration was not significantly more severe in the joints with tropism than in the joints without. Sclerosis was slightly greater in the joints with tropism than in the joints without it. Sclerosis and cartilage degeneration were significantly related to age and spinal level.CONCLUSIONAge, spinal level, and overall facet joint angle are more important factors in facet joint degeneration than is tropism. 相似文献
984.
985.
Cytologic evaluation of the CSF is often difficult when trying to distinguish between truly neoplastic and reactive cells. Several non-neoplastic conditions may be associated with atypical cells in the CSF, a fact the clinician has to consider to avoid inadequate aggressive theraphies. We report here three patients with infectious meningitis (due to Herpes zoster virus in two, and neuroborreliosis in one) and cytologically atypical cerebrospinal fluid lymphocytes. Further characterization showed that the pleocyrosis in these patients was of reactive origin. Cytomorphology is frequently insufficient and histochemical, immuncytochemical and cellular genome analysis techniques may help differentiate atypical reactive cells from neoplastic cells. 相似文献
986.
987.
为探讨钙调素在慢性缺氧性肺动脉高压发病中的作用,将40只Wistar大鼠随机分为四组,I组为正常对照组,不接受任何处理。Ⅱ、Ⅲ、Ⅳ组为实验组,分别间断缺氧1、2、3周,而后采用火焰原子吸收分光光度法及磷酸二酯酶法测定四组大鼠肺组织Ca^2+含量及CaM活性。 相似文献
988.
Emergency physicians and sexual involvement with patients: an Ontario survey 总被引:2,自引:1,他引:1
下载免费PDF全文
![点击此处可从《Canadian Medical Association journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
OBJECTIVE: To describe Ontario emergency physicians' knowledge of colleagues' sexual involvement with patients and former patients, their own personal experience of such involvement, and their attitudes toward postvisit relationships. DESIGN: Mailed survey. SETTING: Ontario. PARTICIPANTS: Emergency physicians practising in Ontario. RESULTS: Of 974 eligible mailed surveys, 599 (61.5%) were returned. Of these respondents, 52 (8.7%) reported being aware of a colleague in emergency practice who had been sexually involved with a patient or former patient. When describing their own behaviour, 37 respondents (6.2%) reported sexual involvement with a former patient. However, of this group, only 9 (25.0%) had met the patient in an emergency department. Thus, of the total number of respondents, only 1.5% (9/599) reported sexual involvement arising out of an emergency department visit. Most respondents (82.4%) agreed that it is inappropriate behaviour to ask a patient for a date after an emergency assessment and before the patient's departure, and 66.4% felt that it is inappropriate to contact the patient after discharge. However, only 10.6% believed it to be unacceptable to request a social meeting after encountering a patient previously cared for in the emergency department in a nonprofessional setting. Most respondents (96.5%) did not believe that sexual involvement could ever be therapeutic for the patient. However, only 66% felt that it was always an abuse of power and 62.4% supported zero tolerance of all sexual involvement between physicians and patients. CONCLUSIONS: Vague regulatory guidelines currently in place have failed to dispel confusion regarding what is acceptable social behaviour for physicians providing emergency care. Our results support the need for clarification, and suggest a basis for guidelines that would be acceptable to the emergency medical community: that an emergency visit should not form the basis for the initiation of personal or sexual relationships, yet neither should it preclude their development in nonmedical settings. 相似文献
989.
The effect of outdoor fungal spore concentrations on daily asthma severity. 总被引:10,自引:2,他引:8
下载免费PDF全文
![点击此处可从《Environmental health perspectives》网站下载免费的PDF全文](/ch/ext_images/free.gif)
R J Delfino R S Zeiger J M Seltzer D H Street R M Matteucci P R Anderson P Koutrakis 《Environmental health perspectives》1997,105(6):622-635
The relationship between day-to-day changes in asthma severity and combined exposures to community air pollutants and aeroallergens remains to be clearly defined. We examined the effects of outdoor air pollutants, fungi, and pollen on asthma. Twenty-two asthmatics ages 9-46 years were followed for 8 weeks (9 May-3 July 1994) in a semirural Southern California community around the air inversion base elevation (1,200 ft). Daily diary responses included asthma symptom severity (6 levels), morning and evening peak expiratory flow rates (PEFR), and as-needed beta-agonist inhaler use. Exposures included 24-hr outdoor concentrations of fungi, pollen, and particulate matter with a diameter < 10 microns (PM10; maximum = 51 micrograms/m3) and 12-hour day-time personal ozone (O3) measurements (90th percentile = 38 ppb). Random effects longitudinal regression models controlled for autocorrelation and weather. Higher temperatures were strongly protective, probably due to air conditioning use and diminished indoor allergens during hot, dry periods. Controlling for weather, total fungal spore concentrations were associated with all outcomes: per minimum to 90th percentile increase of nearly 4,000 spores/m3, asthma symptom scores increased 0.36 (95% CI, 0.16-0.56), inhaler use increased 0.33 puffs (95% CI, -0.02-0.69), and evening PEFR decreased 12.1 l/min (95% CI, -1.8-22.3). These associations were greatly enhanced by examining certain fungal types (e.g., Alternaria, basidiospores, and hyphal fragments) and stratifying on 16 asthmatics allergic to tested deuteromycete fungi. There were no significant associations to low levels of pollen or O3, but inhaler use was associated with PM10 (0.15 inhaler puffs/10 micrograms/m3; p < 0.02). These findings suggest that exposure to fungal spores can adversely effect the daily respiratory status of some asthmatics. 相似文献
990.
L-丙酰肉碱对再灌注心肌损伤的保护及体外抗自由基作用 总被引:1,自引:0,他引:1
目的:观察L-丙酰肉碱对缺血再灌注心肌的保护作用,并探讨其机理。方法:采用大鼠在体心脏冠状动脉前降支阻断5min造成缺血再灌注模型,持续心电监护,观察心律失常与心功能指标;应用电子顺磁共振观察L-丙酰肉碱对Fenton体系及二甲基亚砜(DMSO)碱性有氧体系产生自由基的作用。结果:L-丙酰肉碱静脉给药明显减少再灌注时室性心动过速、室性纤维颤动的发生(P<0.05),促进再灌注后左室收缩压、左室压最大上升速率、左室压最大下降速率、心力环面积的恢复,与对照组相比,各参数均明显增高(P<0.05);静脉注射L-丙酰肉碱100mmol/L时促进Fenton体系OH的产生,而500mmol/L时产生明显抑制作用,L-丙酰肉碱明显抑制DMSO碱性有氧体系OS的产生。结论:L-丙酰肉碱明显减少再灌注心律失常的发生,促进再灌注后心功能的恢复。推测它对自由基的作用可能是再灌注损伤保护机理之一。 相似文献