全文获取类型
收费全文 | 2352906篇 |
免费 | 171377篇 |
国内免费 | 3340篇 |
专业分类
耳鼻咽喉 | 32070篇 |
儿科学 | 75999篇 |
妇产科学 | 62723篇 |
基础医学 | 348534篇 |
口腔科学 | 63652篇 |
临床医学 | 211558篇 |
内科学 | 457937篇 |
皮肤病学 | 51814篇 |
神经病学 | 185409篇 |
特种医学 | 88037篇 |
外国民族医学 | 489篇 |
外科学 | 354130篇 |
综合类 | 47727篇 |
现状与发展 | 12篇 |
一般理论 | 851篇 |
预防医学 | 182891篇 |
眼科学 | 54382篇 |
药学 | 175396篇 |
11篇 | |
中国医学 | 4588篇 |
肿瘤学 | 129413篇 |
出版年
2021年 | 19064篇 |
2019年 | 19591篇 |
2018年 | 27125篇 |
2017年 | 20405篇 |
2016年 | 22807篇 |
2015年 | 25724篇 |
2014年 | 36183篇 |
2013年 | 54054篇 |
2012年 | 74811篇 |
2011年 | 79604篇 |
2010年 | 47164篇 |
2009年 | 44644篇 |
2008年 | 74712篇 |
2007年 | 79592篇 |
2006年 | 80401篇 |
2005年 | 77917篇 |
2004年 | 74494篇 |
2003年 | 71779篇 |
2002年 | 69423篇 |
2001年 | 108786篇 |
2000年 | 111482篇 |
1999年 | 93534篇 |
1998年 | 27004篇 |
1997年 | 23676篇 |
1996年 | 24066篇 |
1995年 | 22725篇 |
1994年 | 20908篇 |
1993年 | 19727篇 |
1992年 | 72036篇 |
1991年 | 70107篇 |
1990年 | 68413篇 |
1989年 | 65690篇 |
1988年 | 60334篇 |
1987年 | 59151篇 |
1986年 | 55250篇 |
1985年 | 53041篇 |
1984年 | 39340篇 |
1983年 | 33417篇 |
1982年 | 19879篇 |
1979年 | 35893篇 |
1978年 | 25683篇 |
1977年 | 21257篇 |
1976年 | 20362篇 |
1975年 | 21835篇 |
1974年 | 26166篇 |
1973年 | 24832篇 |
1972年 | 23217篇 |
1971年 | 22062篇 |
1970年 | 20277篇 |
1969年 | 19337篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Cerebrovascular and metabolic perturbations in delayed heavy charged particle radiation injury 总被引:5,自引:0,他引:5
E H Lo K A Frankel R L Delapaz A Poljak K H Woodruff K M Brennan M H Phillips P E Valk G K Steinberg J I Fabrikant 《Brain research》1989,504(1):168-172
Focal heavy charged particle irradiation of the rabbit brain created defined lesions which were observable by nuclear magnetic resonance (NMR) and positron emission tomography (PET) imaging techniques. The lesions appeared approximately 9-11 months after left partial hemibrain irradiation with 30 Gy (230 MeV/u helium ions), and were restricted to the white matter tracts and deep perithalamic and thalamic regions. 82Rubidium PET and Gadolinium DTPA enhanced NMR imaging were used to detect blood-brain barrier perturbations. 18Fluordeoxyglucose PET studies demonstrated widespread decreases in cerebral glucose uptake in the cortex and thalamus of the irradiated hemisphere. NMR and PET imaging results correlated well with histological findings. Rabbits irradiated with 15 Gy did not demonstrate any abnormalities in the brain with sequential NMR scans through 14 months post-irradiation. 相似文献
992.
993.
Sixty chronic alcoholic patients, aged 35.6 +/- 0.7 years and an average alcoholic history of 9.3 +/- 0.5 years were examined. Atrial fibrillation was detected at 24 h ECG monitoring in 2 (3.45%) patients, and paroxysms of atrial fibrillation or flutter were detected by intracardiac electrophysiologic investigation in 6 (22.2%). Fourteen (44.8%) patients with alcoholic heart damage demonstrated atrial vulnerability, indicative of a predisposition to atrial fibrillation even at earlier stages of alcoholic heart damage. 相似文献
994.
995.
996.
This article examines the distribution of positive blood alcohol levels (BALs) among emergency room patients and the relationship between intoxication and other variables. Approximately one-quarter of the 640 subjects had positive blood alcohol levels and 16.3% had BAL readings above 0.10%, the legal limit for operating a motor vehicle in most states. Chi-square tests and logistic regression analysis indicated a significant relationship between employment status, gender, educational attainment, age and BAL. There were no significant racial differences. Analysis of the role of the presenting problem with BAL revealed that being involved in an accident was significantly predictive of a high BAL in a multivariate context. However, patients presenting with psychiatric problems had overall higher levels of intoxication than other patients. These findings have major implications for public policy formulation vis-à-vis public health delivery. 相似文献
997.
Using a 31P-NMR spectroscopy, we monitored the metabolic kinetics of energy organophosphate compound in rat lens during the process of generating galactose cataract. The most remarkable metabolic change in the earlier phase of galactose cataract formation was found in alpha-glycerophosphate. This increased significantly, as compared to controls, since the day 3 of giving feed containing 25% galactose. The high level lasted for up to three weeks, decrease followed by a gradual decrease and subsequently a significant decrease at five weeks. Adenosine triphosphate (ATP) showed a significant decrease in the galactose group compared to the controls from two weeks after beginning of the experiment and the decrease continued. Inorganic orthophosphate increased gradually in the galactose group as compared to the controls, the increase being of significance at one week reading a maximum at two weeks followed by a subsegment decrease. Our basic study suggests that 31P-NMR spectroscopy is a useful technique in lens of the metabolic kinetics, to noninvasively determine the pathophysiology of galactose cataract, which has been studied biochemically and histologically. 相似文献
998.
The epidemiology of viral hepatitis in US Navy enlisted personnel was reviewed for the years 1975-1984. Hospital discharge summaries of all active duty enlisted personnel admitted to a US Navy treatment facility were used for the study. From 1975 to 1984, total first hospitalizations for viral hepatitis declined from 128 per 100,000 personnel (95% confidence interval (Cl) 118-139) to 56 per 100,000 personnel (95% Cl 50-63). The highest incidence of acute viral hepatitis (115 per 100,000 personnel) was found in the youngest age groups aged 24 years and less. Risk factors for acute hepatitis included a previous hospitalization with either drug abuse (relative risk = 363) or a sexually transmitted disease (relative risk = 25) listed among the discharge diagnoses. Having a medical job classification was also associated with an increased risk of acute hepatitis. The steep decline in the incidence of viral hepatitis during this 10-year period may have been due to decreasing drug abuse in the US Navy. Immunization of high-risk groups in the US Navy with hepatitis B vaccine could be an effective policy for the prevention of acute viral hepatitis. 相似文献
999.
1000.