全文获取类型
收费全文 | 1742篇 |
免费 | 300篇 |
国内免费 | 39篇 |
专业分类
耳鼻咽喉 | 13篇 |
儿科学 | 105篇 |
妇产科学 | 19篇 |
基础医学 | 105篇 |
口腔科学 | 27篇 |
临床医学 | 287篇 |
内科学 | 580篇 |
皮肤病学 | 60篇 |
神经病学 | 182篇 |
特种医学 | 282篇 |
外科学 | 190篇 |
综合类 | 31篇 |
预防医学 | 60篇 |
眼科学 | 16篇 |
药学 | 64篇 |
中国医学 | 1篇 |
肿瘤学 | 59篇 |
出版年
2024年 | 9篇 |
2023年 | 52篇 |
2022年 | 13篇 |
2021年 | 28篇 |
2020年 | 90篇 |
2019年 | 12篇 |
2018年 | 89篇 |
2017年 | 69篇 |
2016年 | 69篇 |
2015年 | 60篇 |
2014年 | 94篇 |
2013年 | 111篇 |
2012年 | 50篇 |
2011年 | 38篇 |
2010年 | 78篇 |
2009年 | 112篇 |
2008年 | 41篇 |
2007年 | 46篇 |
2006年 | 49篇 |
2005年 | 29篇 |
2004年 | 17篇 |
2003年 | 11篇 |
2002年 | 15篇 |
2001年 | 31篇 |
2000年 | 16篇 |
1999年 | 28篇 |
1998年 | 80篇 |
1997年 | 96篇 |
1996年 | 78篇 |
1995年 | 69篇 |
1994年 | 51篇 |
1993年 | 54篇 |
1992年 | 28篇 |
1991年 | 14篇 |
1990年 | 26篇 |
1989年 | 54篇 |
1988年 | 44篇 |
1987年 | 29篇 |
1986年 | 22篇 |
1985年 | 22篇 |
1984年 | 17篇 |
1983年 | 9篇 |
1982年 | 14篇 |
1981年 | 14篇 |
1980年 | 14篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1976年 | 10篇 |
1975年 | 8篇 |
1971年 | 8篇 |
排序方式: 共有2081条查询结果,搜索用时 15 毫秒
151.
MD Pavlovi DM Karadagli LO Kandolf P Mijukovi 《Journal of the European Academy of Dermatology and Venereology》2001,15(1):54-58
Three cases of persistent erythema multiforme, two of unknown aetiology and one precipitated by influenza are reported. Lesions were widespread, mostly atypical in appearance and regressed in response to immunosuppressants (systemic steroids and/or azathioprine) or, in one case, to dapsone. One patient developed erythroderma responding eventually to etretinate. Histology in all patients was consistent with the mixed, epidermodermal pattern of erythema multiforme. There were no significant laboratory abnormalities nor marked symptomatology apart from itching. The persistent form appears to belong to the spectrum of erythema multiforme being heterogeneous with respect to inducing stimuli, including viral antigens, neoplastic or inflammatory disease or unknown causes. Whenever it is possible, treatment should be adjusted depending on the causative agent. 相似文献
152.
Vinita J. Acharya MD Jayant N. Acharya MD DM Charles H. Tegeler MD Pearse Morris MD Dana Meads RVT Cormac A. O''Donovan MD 《Journal of neuroimaging》2002,12(2):153-157
BACKGROUND: Electroencephalography (EEG) is traditionally used to assess the duration of hemispheric anesthetization and to monitor return of function in the anesthetized hemisphere during the intracarotid amobarbital procedure (IAP), but EEG changes are not consistently seen. The authors evaluated the role of continuous transcranial Doppler (TCD) monitoring as an alternative to EEG. METHODS: The authors performed both continuous TCD monitoring and EEG during the IAP in 10 patients with medically intractable partial epilepsy. Mean velocities were monitored continuously in both middle cerebral arteries (MCAs), and changes in MCA velocities on continuous TCD monitoring were time locked with the EEG changes. RESULTS: The average mean MCA velocities were within normal limits bilaterally (50-85 cm/s) in all patients at baseline. Mean MCA velocites increased in all patients to 95-115 cm/s at the start of the test when the patients were asked to raise their hands and start counting. After injection of sodium amobarbital, mean MCA velocities in all patients dropped dramatically on the ipsilateral side to values of 12-39 cm/s and returned to the baseline average value when the hemiparesis recovered. In 8 patients, the duration of delta activity on EEG coincided with the time interval during which the mean MCA velocities were low on TCD monitoring. In 2 patients, despite the presence of hemiparesis clinically and a drop in mean MCA velocities on the ipsilateral side on continuous TCD monitoring, EEG remained normal on the ipsilateral side. CONCLUSIONS: Continuous TCD monitoring may be a more sensitive method than EEG in determining the duration of hemispheric anesthetization during IAP. Because the items for assessment of memory are presented during the period of hemispheric anesthetization, TCD may be useful in more precisely defining the time window for memory testing. 相似文献
153.
Prof Robert Beaglehole DSc Prof Shah Ebrahim DM Prof Srinath Reddy MD Janet Voûte MA Prof Steve Leeder MD 《Lancet》2008,370(9605):2152-2157
Chronic (non-communicable) diseases—principally cardiovascular diseases, cancer, chronic respiratory diseases, and diabetes—are leading causes of death and disability but are surprisingly neglected elements of the global-health agenda. They are underappreciated as development issues and underestimated as diseases with profound economic effects. Achievement of the global goal for prevention and control of chronic diseases would avert 36 million deaths by 2015 and would have major economic benefits. The main challenge for achievement of the global goal is to show that it can be reached in a cost-effective manner with existing interventions. This series of papers in The Lancet provides evidence that this goal is not only possible but also realistic with a small set of interventions directed towards whole populations and individuals who are at high risk. The total yearly cost of the interventions in 23 low-income and middle-income countries is about US$5·8 billion (as of 2005). In this final paper in the Series we call for a serious and sustained worldwide effort to prevent and control chronic diseases in the context of a general strengthening of health systems. Urgent action is needed by WHO, the World Bank, regional banks and development agencies, foundations, national governments, civil society, non-governmental organisations, the private sector including the pharmaceutical industry, and academics. We have established the Chronic Disease Action Group to encourage, support, and monitor action on the implementation of evidence-based efforts to promote global, regional, and national action to prevent and control chronic diseases. 相似文献
154.
The recent Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC) reiterated long-standing recommendations that Stage 1 hypertension (BP ≥ 140/90 mm Hg) without comorbidity should be treated initially with diuretics (DI) or beta blockers (BB). Yet market research suggests that many physicians prefer to use other drug classes, such as calcium channel blockers and ACE inhibitors.
OBJECTIVES: To explore the determinants of therapeutic choice in hypertension.
METHODS: We surveyed by mail a stratified random sample of 10,000 U.S. cardiologists, internists, and family/general practitioners. Physicians were queried about their practice environment and their knowledge, attitudes, and practices regarding antihypertensive therapy, including their choice of drugs to treat patients with specified clinical profiles. The probability that physicians would follow JNC guidelines Stage 1 hypertension was analyzed using multiple logistic regression with stepwise backward elimination to select variable with p < 0.001.
RESULTS: Completed surveys were received from 1,023 physicians. 86.7% prescribe drug therapy for Stage 1 hypertension, and 19.5% (22.5% of drug prescribers) limit their choices to DI and BB. Guideline conformity was higher among physicians who: practice in academic medical centrers; are older; are general practitioners (versus general internists); have smaller caseloads; have fewer hypertensive patients; have higher proportions of HMO, Medicaid, and uninsured patients; and experience more formulary restrictions. Cardiologists and family practitioners were less likely than internists to follow guidelines.
CONCLUSION: JNC guidelines are better accepted by academic physicians, older physicians who have more expenence using DI and BB, physicians with smaller caseloads and hence more time for follow-up and therapy adjustment, and physicians who face drug reimbursement constraints. 相似文献
OBJECTIVES: To explore the determinants of therapeutic choice in hypertension.
METHODS: We surveyed by mail a stratified random sample of 10,000 U.S. cardiologists, internists, and family/general practitioners. Physicians were queried about their practice environment and their knowledge, attitudes, and practices regarding antihypertensive therapy, including their choice of drugs to treat patients with specified clinical profiles. The probability that physicians would follow JNC guidelines Stage 1 hypertension was analyzed using multiple logistic regression with stepwise backward elimination to select variable with p < 0.001.
RESULTS: Completed surveys were received from 1,023 physicians. 86.7% prescribe drug therapy for Stage 1 hypertension, and 19.5% (22.5% of drug prescribers) limit their choices to DI and BB. Guideline conformity was higher among physicians who: practice in academic medical centrers; are older; are general practitioners (versus general internists); have smaller caseloads; have fewer hypertensive patients; have higher proportions of HMO, Medicaid, and uninsured patients; and experience more formulary restrictions. Cardiologists and family practitioners were less likely than internists to follow guidelines.
CONCLUSION: JNC guidelines are better accepted by academic physicians, older physicians who have more expenence using DI and BB, physicians with smaller caseloads and hence more time for follow-up and therapy adjustment, and physicians who face drug reimbursement constraints. 相似文献
155.
Ductal carcinoma in situ: atypical mammographic appearances 总被引:5,自引:0,他引:5
156.
157.
Two point mutations in homology domain II of the house fly Vssc1 voltage-sensitive sodium channel α subunit, M918T and L1014F, are associated with resistance to pyrethroid insecticides and reduce the pyrethroid sensitivity of Vssc1 sodium channels expressed in Xenopus laevis oocytes. To assess the impact of these residues as determinants of pyrethroid sensitivity in another sequence context, we mutated the corresponding positions of the rat pyrethroid-sensitive, TTX-resistant peripheral nerve sodium channel (rNav1.8; also called SNS or PN3) and determined the sensitivity of native and mutated channels expressed in Xenopus oocytes to the pyrethroid insecticide cismethrin. The rNav1.8 channel, like other vertebrate sodium channel isoforms, contains a conserved isoleucine residue at sequence position 780 that aligns with the conserved methionine at position 918 of Vssc1 and other insect sodium channels. Channels mutated to contain methionine at position 780 (I780M) exhibited enhanced sensitivity to cismethrin and larger decay constants for pyrethroid-modified channel states. In contrast, the mutation corresponding to M918T in the Vssc1 channel (I780T) profoundly decreased the cismethrin sensitivity of expressed channels. Insertion of the mutation corresponding to L1014F (L879F in rNav1.8) reduced the cismethrin sensitivity of channels having either isoleucine or methionine at position 780, whereas channels containing the I780T/L879F double mutation were insensitive to this insecticide. Mutations at Ile780 and Leu879 also modified the voltage dependence of rNav1.8 channels, but these effects were not related to changes in pyrethroid sensitivity. These results confirm the importance of residues in homology domain II as fundamental determinants of the pyrethroid sensitivity of sodium channels. 相似文献
158.
The effect of a graded exercise protocol on phosphorus-31 magnetic resonance (MR) spectroscopy of calf skeletal muscle in nine healthy (control) subjects and 16 patients with symptomatic peripheral arterial occlusive disease (PAOD) was assessed. Ankle-brachial pressure indexes were obtained in all 16 patients, and 10 patients underwent peripheral arteriography. Temporal profiles of pH and the inorganic phosphorus (Pi) index were calculated from the spectra. A Pi-index recovery rate constant was calculated for each subject. Arteriograms were graded by calculating the runoff resistance in the limb of interest. The pH profiles during exercise did not differ significantly between the PAOD patients and control subjects. The Pi-index recovery rate constant in the PAOD patients was significantly (P less than .01) smaller than in the control subjects. There was no significant correlation between recovery rate and the ankle-brachial pressure indexes, but there was a strong negative correlation between recovery rates and angiographic resistance grades, with smaller recovery rate constants in patients with increased arterial resistance. It is concluded that P-31 MR spectroscopy shows promise as a direct measure of tissue perfusion. 相似文献
159.
160.
In a 5-year period, 92 patients with biliary obstruction proximal to the pancreatic segment were evaluated with computed tomography (CT). Seventy-three were judged to have technically optimal studies. Observations of the level of obstruction were compared with data from 50 percutaneous transhepatic cholangiograms; CT data enabled the level of obstruction to be correctly predicted in 46. CT enabled correct prediction of the distribution of obstructing lesions in all 18 patients with intrahepatic obstruction. Forty-four of the 73 patients had pathologic examination of the porta hepatitis. CT findings of obstructing mass and lesser omental nodes resulted in correct prediction of malignancy in 25 (92%) of 27 patients; the absence of such findings enabled correct prediction of benign disease in 13 (77%) of 17 individuals. CT is most valuable as a noninvasive means of planning surgical or radiologic drainage procedures in patients with biliary obstruction. 相似文献