全文获取类型
收费全文 | 11093篇 |
免费 | 617篇 |
国内免费 | 110篇 |
专业分类
耳鼻咽喉 | 184篇 |
儿科学 | 158篇 |
妇产科学 | 239篇 |
基础医学 | 1714篇 |
口腔科学 | 239篇 |
临床医学 | 873篇 |
内科学 | 1964篇 |
皮肤病学 | 563篇 |
神经病学 | 667篇 |
特种医学 | 708篇 |
外科学 | 1804篇 |
综合类 | 56篇 |
一般理论 | 1篇 |
预防医学 | 606篇 |
眼科学 | 188篇 |
药学 | 933篇 |
中国医学 | 157篇 |
肿瘤学 | 766篇 |
出版年
2023年 | 57篇 |
2022年 | 231篇 |
2021年 | 352篇 |
2020年 | 176篇 |
2019年 | 275篇 |
2018年 | 297篇 |
2017年 | 213篇 |
2016年 | 349篇 |
2015年 | 487篇 |
2014年 | 585篇 |
2013年 | 677篇 |
2012年 | 975篇 |
2011年 | 951篇 |
2010年 | 587篇 |
2009年 | 452篇 |
2008年 | 654篇 |
2007年 | 604篇 |
2006年 | 552篇 |
2005年 | 555篇 |
2004年 | 425篇 |
2003年 | 372篇 |
2002年 | 331篇 |
2001年 | 214篇 |
2000年 | 224篇 |
1999年 | 178篇 |
1998年 | 78篇 |
1997年 | 56篇 |
1996年 | 55篇 |
1995年 | 38篇 |
1994年 | 32篇 |
1993年 | 28篇 |
1992年 | 57篇 |
1991年 | 52篇 |
1990年 | 51篇 |
1989年 | 38篇 |
1988年 | 46篇 |
1987年 | 38篇 |
1986年 | 45篇 |
1985年 | 48篇 |
1984年 | 38篇 |
1983年 | 48篇 |
1981年 | 18篇 |
1980年 | 16篇 |
1979年 | 29篇 |
1978年 | 28篇 |
1977年 | 22篇 |
1976年 | 20篇 |
1975年 | 15篇 |
1974年 | 17篇 |
1973年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Increase in signal intensities on T1-weighted magnetic resonance images in asymptomatic manganese-exposed workers 总被引:6,自引:0,他引:6
Kim Y Kim KS Yang JS Park IJ Kim E Jin Y Kwon KR Chang KH Kim JW Park SH Lim HS Cheong HK Shin YC Park J Moon Y 《Neurotoxicology》1999,20(6):901-907
OBJECTIVES: To clarify the clinical significance of increased signal intensities on T1 weighted magnetic resonance imaging (MRI) we performed a large-scale epidemiological study on asymptomatic manganese (Mn)-exposed workers with its focus on MRI. METHODS: We randomly selected 121 male workers out of a total of 750 workers including Mn-exposed, non-exposed manual, and non-exposed clerical workers in the factories. We studied environmental and biological monitoring, neurological examination, and MRI. RESULTS: The proportion of workers with increased signal intensities among the exposed, the non-exposed manual workers, and the non-exposed clerical workers was 46.1%, 18.8%, and 0%, respectively. Especially, 73.5% of the welders showed increased signal intensities. In no subject, were clinical signs of manganism observed. The pallidal index correlated with blood Mn concentration. CONCLUSION: Increase in signal intensities on the T1-weighted image reflect recent exposure to Mn, but not necessarily manganism. At which increase of signal intensity, the progression of manganism from Mn exposure occurs, remains to be solved. 相似文献
62.
Michaels AJ Michaels CE Zimmerman MA Smith JS Moon CH Peterson C 《The Journal of trauma》1999,47(5):867-873
OBJECTIVE: Posttraumatic Stress Disorder (PTSD) impairs outcome from injury. We present a path analysis of factors related to the development of PTSD in injured adults. METHODS: A prospective cohort of 250 patients without severe neurotrauma was evaluated by interview during admission and by mailed self-report 6 months later. Data were gathered from the trauma registry (age, injury mechanism, and Injury Severity Score), social history (gender, income, education, and social support), and survey instruments. Baseline assessment used the Michigan Critical Events Perception Scale (peritraumatic dissociation and subjective threat to life), the Life Experience Survey (stressful exposure history), and the SF36 (general and mental health). PTSD at 6 months was identified with the civilian Mississippi Scale for PTSD. Data are listed as mean +/- SEM or percent (%). Path analysis was conducted by linear regression and significant (p<0.05) variables are shown. Factors are listed with the standardized beta. A negative beta suggests a protective effect. RESULTS: The 176 patients (72%) who completed the 6-month follow-up were 37.7+/-0.88 years old; 75% were men; and blunt (70%), penetrating (13.5%), and burn (16.4%) mechanisms caused the injuries. Assault was involved in 14.5% of the cases. Average income was $44,300+/-2,700/yr, education was 13.0+/-0.15 years, and Injury Severity Score was 13.9+/-0.50. A total of 42.3% of the patients developed PTSD. The 39.7% of the variance in PTSD explained by the model was due to intentional injury (beta = 0.27), male gender (beta = -0.21), age (beta = -0.20), peritraumatic dissociation (beta = 0.174), baseline mental health (beta = -0.21), and prior life-threatening illness (beta = -0.29). Peritraumatic dissociation was due to the patient's sense of threat to life (beta = -0.47), and threat was related to Injury Severity Score (beta = 0.2), assault(beta = 0.14), education (beta = -0.15), and age (beta = -0.19). Baseline SF36 mental health was related to social support (beta = 0.27) and income (beta = 0.21). Income was contingent on education (beta = 0.21). CONCLUSION: PTSD occurred in 42.3% of injured adults 6 months after trauma and was related to assault, dissociation, female gender, youth, poor mental health, and prior illness. By modeling PTSD, we may learn more of the etiology, risk stratification, and potentials for the treatment of this common and important morbidity of injury. 相似文献
63.
Clinical significance of respiratory bronchiolitis on open lung
biopsy and its relationship to smoking related interstitial lung
disease 下载免费PDF全文
BACKGROUND: Respiratory bronchiolitis-associated interstitial lung disease (RBILD) is a rare form of interstitial lung disease which may present in similar fashion to other types of chronic interstitial pneumonia. The purpose of this study was to undertake a clinicopathological review of 10 patients with RBILD and to examine the clinical and imaging data related to its histopathological pattern, in particular the relationship of RBILD to smoking. METHODS: Thirteen out of 168 retrospectively reviewed patients, from whom biopsy specimens were taken for suspected diffuse lung disease, were identified with a histopathological pattern of RBILD. Three cases were rejected as follow up data were unavailable. The 10 remaining cases constituted the study group and both clinical and imaging data were collected from patients' notes and referring physicians. RESULTS: Histopathologically, four cases of RBILD overlapped with the pattern of desquamative interstitial pneumonitis (DIP) and nine also had microscopic evidence of centrilobular emphysema. Nine patients were smokers, ranging from 3 to 80 pack years. The one non-smoker had an occupational exposure to the fumes of solder flux. The sex distribution was equal with an age range of 32-65 years. Two patients were clubbed. Lung function tests showed both restrictive and obstructive patterns together with severe reductions in carbon monoxide transfer factor in seven patients. Chest radiographs showed reticular or reticulonodular infiltrates in five patients and a ground glass pattern in two. CT scans were consistent with either DIP or RBILD in six of eight patients. Although seven patients remained stable or improved, either with or without treatment, three patients deteriorated. CONCLUSIONS: This study adds weight to the hypothesis that smoking can cause clinically significant interstitial lung disease, with deterioration in pulmonary function despite treatment. Given the overlapping histopathological patterns of RBILD and DIP and their strong association with smoking, the term "smoking related interstitial lung disease" is suggested for those patients who are smokers. 相似文献
64.
65.
66.
Theoretically, Medicare provides one standard benefit package to all enrollees. But because of State-level variations in populations, service supply, and local practice patterns, national policy changes may have unequal impacts on access and service utilization. Across-the-board policy changes may create hardships in one area while appropriately discouraging use in another area. In this article, the authors describe State-level variations in Medicare enrollees, their insurance coverage, 1995 Medicare and beneficiary spending patterns in aggregate, per capita, and by service, and certain spending patterns for dually eligible beneficiaries. These data are useful for considering the State-level effects of payment reform. 相似文献
67.
Lim YH Leem MJ Shin DH Chang HB Hong SW Moon EY Lee DK Yoon SJ Woo WS 《Archives of pharmacal research》1999,22(2):208-212
Activity-guided fractionation of the roots of Anthriscus sylvestris resulted in the isolation and characterization of five cytotoxic compounds, deoxypodophyllotoxin (1), falcarindiol (2), and angeloyl podophyllotoxin (5) from the hexane soluble fraction and morelensin (3), bursehernin (4) from the chloroform soluble fraction. It is the first report of the occurrence of compound 5 in nature. 相似文献
68.
DW2282,(S)-(+)-4-phenyl-1-[1-(4-aminobenzoyl)-indoline-5-sulfonyl] -4,5-dihydro-2-imidazolone hydrochloride, is a new anticancer agent which is thought to exhibit a characteristic mechanism of action in the inhibition of tumor growth. In this study, we estimated the toxicities of DW2282 in mice. When mice were orally dosed for five consecutive days at the dosages of 50, 100 and 150 mg/kg, DW2282 did not induce methemoglobinemia and hypoglycemia at any of these doses. However, increased ALT and AST values were observed in the 150 mg/kg dosing group, and white blood cells (WBC) were significantly decreased at all doses. However, the changes in WBC count, ALT and AST immediately reversed after the cessation of drug administration. In addition, we found that DW2282 did not cause an increase in hemolysis in human blood. Taken together, these data suggested that DW2282 may have a relatively low level of toxicity, and that there may be a quick recovery from any toxicity it does produce. 相似文献
69.
Aliphatic esters of protocatechuic acid (PA,1), vanillic acid (VA,9) and gallic acid (GA,18) were prepared and their anti-thrombotic effects were evaluated in the mouse model of thrombosis. The aliphatic groups included methyl, ethyl,n-propyl,i-propyl,n-butyl,i-butyl,n-amyl and cyclohexyl.n-Amyl ester of PA (7), i-propyl and cyclohexyl esters of VA (13 and17 respectively) and ethyl ester of GA (20) treatment significantly lowered the death rate and increased the recovery from paralysis due to the thrombotic challenge. From the limited analogs available, it was tentatively concluded that the structural conformation, where carboxy oxygen (=O or-O?) of the carboxyl group (COOH) at C1 and the oxygen function at C3 (either OH or OCH3) are closely situated, is favorable for the esters of PA, VA and GA to be more antithrombotic. 相似文献
70.