全文获取类型
收费全文 | 1236篇 |
免费 | 133篇 |
国内免费 | 15篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 41篇 |
妇产科学 | 12篇 |
基础医学 | 174篇 |
口腔科学 | 19篇 |
临床医学 | 131篇 |
内科学 | 274篇 |
皮肤病学 | 10篇 |
神经病学 | 118篇 |
特种医学 | 150篇 |
外科学 | 83篇 |
综合类 | 69篇 |
预防医学 | 119篇 |
眼科学 | 13篇 |
药学 | 90篇 |
中国医学 | 2篇 |
肿瘤学 | 75篇 |
出版年
2023年 | 9篇 |
2022年 | 4篇 |
2021年 | 14篇 |
2020年 | 15篇 |
2019年 | 20篇 |
2018年 | 26篇 |
2017年 | 19篇 |
2016年 | 17篇 |
2015年 | 20篇 |
2014年 | 34篇 |
2013年 | 32篇 |
2012年 | 40篇 |
2011年 | 40篇 |
2010年 | 35篇 |
2009年 | 44篇 |
2008年 | 52篇 |
2007年 | 40篇 |
2006年 | 55篇 |
2005年 | 56篇 |
2004年 | 44篇 |
2003年 | 45篇 |
2002年 | 41篇 |
2001年 | 39篇 |
2000年 | 35篇 |
1999年 | 49篇 |
1998年 | 44篇 |
1997年 | 44篇 |
1996年 | 32篇 |
1995年 | 30篇 |
1994年 | 34篇 |
1993年 | 21篇 |
1992年 | 27篇 |
1991年 | 24篇 |
1990年 | 25篇 |
1989年 | 36篇 |
1988年 | 32篇 |
1987年 | 32篇 |
1986年 | 33篇 |
1985年 | 29篇 |
1984年 | 14篇 |
1983年 | 18篇 |
1982年 | 11篇 |
1981年 | 12篇 |
1980年 | 10篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1977年 | 8篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1968年 | 3篇 |
排序方式: 共有1384条查询结果,搜索用时 15 毫秒
81.
82.
Cancer and cardiac mortality among 15-year survivors of cancer diagnosed during childhood or adolescence. 总被引:2,自引:0,他引:2
PURPOSE: To evaluate the impact of cardiac disease and second malignant neoplasms on late mortality rate and to identify risk factors for late mortality among 15-year survivors of cancer diagnosed during childhood or adolescence. PATIENTS AND METHODS: Gender-specific all-cause and cause-specific (cardiac disease, cancer) standardized mortality ratios were calculated. Kaplan-Meier survival estimates and Cox regression analyses were performed to determine the relationship of several demographic and treatment variables to survival. RESULTS: Patients who survived for 15 years after diagnosis had excess subsequent all-cause, cancer (second malignant neoplasms only), and cardiac mortality rates. No decrease in the late mortality rate by treatment era (1960 to 1970, 1971 to 1984) was identified. Risk factors for males included disease recurrence during the first 15 years after diagnosis, treatment with doxorubicin, and the diagnosis of Hodgkin's disease. Those for females included treatment with radiation therapy, treatment with an alkylating agent, and disease recurrence during the first 15 years after diagnosis. Cox regression analysis demonstrated that only an initial duration of remission of less than 15 years (P <.01) and treatment with doxorubicin (P =.08) were significantly associated with shorter survival time for males. No variable was significantly associated with shorter survival time for females in Cox regression analysis. CONCLUSION: Fifteen-year survivors of childhood cancer have excess mortality. More effective treatments must be developed to reduce this excess risk. Fifteen-year relapse-free survivors did not have excess mortality. This group will require continued observation to determine whether excess mortality will become apparent as more events occur. 相似文献
83.
Posteroanterior (PA) and caudally angulated PA views were obtained in 20 patients undergoing routine coronary arteriography. Although the left main coronary artery (LMCA) was seen well on both views in all patients, the PA-caudal view improved depiction of the LMCA bifurcation in 15 (75%). In addition, the PA-caudal view markedly improved depiction of the circumflex artery, affording optimal depiction of this artery and its branches in 78%-89% of patients. Neither the PA nor the PA-caudal view allowed adequate depiction of the left anterior descending artery. Thus, the PA-caudal view should supplant the PA view in routine coronary arteriography. 相似文献
84.
L-3,4-dihydroxyphenylalanine (levodopa) lowers central nervous system S-adenosylmethionine concentrations in humans. 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Journal of neurology, neurosurgery, and psychiatry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
To determine whether levodopa reduces the levels of S-adenosylmethionine in the human central nervous system, cerebrospinal fluid (CSF) concentrations of S-adenosylmethionine, methionine, 3-methoxytyrosine, levodopa and 5-methyltetrahydrofolate were measured in six children with dopamine deficiency before and after treatment. In four, the lack of dopamine was secondary to a reduction in concentration of levodopa and these were treated with levodopa together with a peripheral dopa-decarboxylase inhibitor. In the other two, levodopa in the central nervous system naturally accumulated due to a congenital deficiency of aromatic-L-amino acid decarboxylase and these were treated with pyridoxine (which in this condition lowers central levodopa concentrations). Raising levodopa concentrations in the central nervous system caused a fall in CSF S-adenosyl-methionine concentration and a rise in CSF 3-methoxytyrosine concentration. No change was observed in CSF methionine concentration and in all patients CSF 5-methyltetrahydrofolate concentration was normal. With one exclusion there was a linear relationship between CSF S-adenosylmethionine and 3-methoxytyrosine concentrations. This is the first demonstration of such effects in humans and the implications upon levodopa therapy are discussed. 相似文献
85.
Harry Hyland Kerr 《American journal of surgery》1935,28(2):364-369
Eight cases of retinitis pigmentosa have been operated on with no results in 5, and improvement in 3.The 5 cases were all in advanced stages of the disease and did not respond to surgical treatment.The 3 cases of moderate visual impairment all improved following sympathectomy.It is, therefore, suggested that superior cervical sympathectomy gives the only chance for improvement in retinitis pigmentosa, provided the pathological process has not advanced so far as to reduce vision below one tenth normal, and the macula has not been encroached upon materially. The criteria for operation should be the ophthalmoscopic findings. Those cases in which the pigment migration is limited to the periphery of the fundus are the most satisfactory for surgical treatment.We believe that operation is definitely contraindicated in cases in which central vision is reduced to less than 10 per cent of normal, and where the fields occupy a circle less than the 10 ° radius. 相似文献
86.
PL.RM. Palaniappan Selvi Sabhanayakam N. Krishnakumar M. Vadivelu 《Food and chemical toxicology》2008,46(7):2440-2444
Catla catla fingerlings were reared in freshwater and exposed to 15.5 ppm concentration of lead for 60 days. The morphological changes on the gill of the C. catla fingerlings due to lead intoxication and the effect of DMSA (meso 2,3-dimercaptosuccinic acid) on the affected tissues were observed using Scanning Electron Microscope. It has been found that the lead treated gill tissues showed certain marked changes, such as cell hypertrophy, alteration in the lamellar surfaces, epithelial hyperplasia and the fusion of adjacent lamellae. The antidote DMSA treatment reduces the toxic effects and helps the recovery of gill tissue and its return to the level of the control/normal. 相似文献
87.
In vitro antiviral activity of dammar resin triterpenoids 总被引:3,自引:0,他引:3
B L Poehland B K Carté T A Francis L J Hyland H S Allaudeen N Troupe 《Journal of natural products》1987,50(4):706-713
Nine triterpenes with antiviral activity against Herpes simplex virus types I and II in vitro were isolated from dammar resin. Each compound caused a significant reduction in viral cytopathic effect when Vero cells were exposed continuously to 1-10 micrograms/ml of compound for 48 h after viral challenge. The triterpenes were identified as dammaradienol [1], dammarenediol-II [2], hydroxydammarenone-I [3], ursonic acid [5], hydroxyhopanone [11], dammarenolic acid [15], shoreic acid [16], eichlerianic acid [17], and a novel compound, hydroxyoleanonic lactone [7], on the basis of their chromatographic, spectroscopic, and physical properties. 相似文献
88.
Perceived treatment difficulty and therapeutic alliance on an adolescent psychiatric hospital unit 总被引:1,自引:0,他引:1
D B Colson C Cornsweet T Murphy F O'Malley P S Hyland M McParland L Coyne 《The American journal of orthopsychiatry》1991,61(2):221-229
On an 8-bed adolescent psychiatric unit, 69 patients were rated over the course of more than one year [corrected]. A set of rating scales was used to determine the relationships of treatment and therapeutic alliance difficulties with staff ratings of patient qualities, family issues, and treatment outcome. Findings underscore the clinical relevance of treatment difficulty and therapeutic alliance in conceptualizing the therapeutic action of the hospital treatment. 相似文献
89.
90.
The effect of intravenous injections or infusions of the opioid receptor antagonist naloxone on the secretion of luteinizing hormone (LH) was studied in 18 spayed cats anaesthetized with Althesin. Effective injections significantly increased the LH concentration of plasma samples (taken every 10-15 min and measured by radio-immunoassay) to a peak 20-30 min after injection. The concentration thereafter declined exponentially (ke = 0.42), and, in 4/8 trials rose again significantly and declined again without further injection. The threshold dose was between 0.4 and 0.5 mg/kg. There did not appear to be a dose dependence of the effect above threshold. Infusion of naloxone at levels up to 5 mg/kg/h was effective in producing a pulsatile release of LH and repeated injections of threshold doses (0.5 mg/kg) could produce a maintained plateau and pulsatile release at frequencies comparable to pulse frequencies in vivo. 相似文献