全文获取类型
收费全文 | 2987篇 |
免费 | 184篇 |
国内免费 | 1篇 |
专业分类
耳鼻咽喉 | 39篇 |
儿科学 | 80篇 |
妇产科学 | 76篇 |
基础医学 | 428篇 |
口腔科学 | 183篇 |
临床医学 | 250篇 |
内科学 | 467篇 |
皮肤病学 | 36篇 |
神经病学 | 265篇 |
特种医学 | 163篇 |
外科学 | 367篇 |
综合类 | 21篇 |
预防医学 | 367篇 |
眼科学 | 22篇 |
药学 | 248篇 |
1篇 | |
肿瘤学 | 159篇 |
出版年
2021年 | 29篇 |
2020年 | 24篇 |
2019年 | 40篇 |
2018年 | 44篇 |
2017年 | 43篇 |
2016年 | 39篇 |
2015年 | 43篇 |
2014年 | 76篇 |
2013年 | 129篇 |
2012年 | 165篇 |
2011年 | 179篇 |
2010年 | 80篇 |
2009年 | 88篇 |
2008年 | 164篇 |
2007年 | 150篇 |
2006年 | 149篇 |
2005年 | 160篇 |
2004年 | 133篇 |
2003年 | 130篇 |
2002年 | 125篇 |
2001年 | 73篇 |
2000年 | 55篇 |
1999年 | 61篇 |
1998年 | 33篇 |
1997年 | 37篇 |
1996年 | 24篇 |
1995年 | 21篇 |
1993年 | 21篇 |
1992年 | 50篇 |
1991年 | 43篇 |
1990年 | 34篇 |
1989年 | 53篇 |
1988年 | 44篇 |
1987年 | 41篇 |
1986年 | 42篇 |
1985年 | 33篇 |
1984年 | 31篇 |
1983年 | 34篇 |
1982年 | 24篇 |
1981年 | 19篇 |
1979年 | 27篇 |
1978年 | 22篇 |
1976年 | 27篇 |
1975年 | 21篇 |
1973年 | 27篇 |
1972年 | 25篇 |
1971年 | 26篇 |
1970年 | 27篇 |
1969年 | 18篇 |
1968年 | 24篇 |
排序方式: 共有3172条查询结果,搜索用时 15 毫秒
101.
Kenton L. Morgan Ian G. Handel Vincent N. Tanya Saidou M. Hamman Charles Nfon Ingrid E. Bergman Viviana Malirat Karl J. Sorensen Barend M. de C. Bronsvoort 《Emerging infectious diseases》2014,20(12):2048-2054
Herdsman-reported disease prevalence is widely used in veterinary epidemiologic studies, especially for diseases with visible external lesions; however, the accuracy of such reports is rarely validated. Thus, we used latent class analysis in a Bayesian framework to compare sensitivity and specificity of herdsman reporting with virus neutralization testing and use of 3 nonstructural protein ELISAs for estimates of foot-and-mouth disease (FMD) prevalence on the Adamawa plateau of Cameroon in 2000. Herdsman-reported estimates in this FMD-endemic area were comparable to those obtained from serologic testing. To harness to this cost-effective resource of monitoring emerging infectious diseases, we suggest that estimates of the sensitivity and specificity of herdsmen reporting should be done in parallel with serologic surveys of other animal diseases. 相似文献
102.
103.
104.
Kirsten Avlund PhD DrMedSc Kirsten Schultz-Larsen MD PhD Ulla Krustrup DDS PhD Niels Christiansen DDS PhD Poul Holm-Pedersen DDS DrOdont 《Journal of the American Geriatrics Society》2009,57(7):1206-1212
OBJECTIVES: To analyze whether inflammatory processes in the periodontium in early old age are related to subsequent mortality during 21 years of follow-up in a nondisabled 70-year-old population.
SETTING: Community-based population in Copenhagen.
DESIGN: The study was based on the Glostrup Aging Study of the 1914 population, with baseline in 1984 when the participants were 70 years old and follow-up 21 years later.
PARTICIPANTS: Three hundred thirty-five dentate men and women participated in the clinical oral health examination.
MEASUREMENTS: Severe periodontal inflammation was measured for all teeth present as the number of teeth with inflammation and periodontal pockets 6 mm deep or more. Mortality data were obtained from the Danish Death Register at 21-year follow-up. The Cox proportional hazards regression model was used. Covariates were measured at baseline and included number of teeth, caries, sex, education, income, hypertension, diabetes mellitus, osteoarthritis, arteriostenosis, myocardial infarction, comorbidity, fatigue, and ability to brush teeth.
RESULTS: The analyses showed that severe periodontal inflammation in at least three teeth at age 70 was marginally related to mortality during 21-year follow-up (crude hazard ratio (HR)=1.17, 95% confidence interval (CI)=0.91–1.78). The estimate increased slightly when adjusted for sex, income, fatigue, and smoking (adjusted HR=1.37, 95% CI=0.97–1.92). The estimates were attenuated when adjusted for the specific diseases, especially arteriostenosis and osteoarthritis.
CONCLUSION: Inflammation in the periodontium in early old age tends to be associated with mortality in older age. 相似文献
SETTING: Community-based population in Copenhagen.
DESIGN: The study was based on the Glostrup Aging Study of the 1914 population, with baseline in 1984 when the participants were 70 years old and follow-up 21 years later.
PARTICIPANTS: Three hundred thirty-five dentate men and women participated in the clinical oral health examination.
MEASUREMENTS: Severe periodontal inflammation was measured for all teeth present as the number of teeth with inflammation and periodontal pockets 6 mm deep or more. Mortality data were obtained from the Danish Death Register at 21-year follow-up. The Cox proportional hazards regression model was used. Covariates were measured at baseline and included number of teeth, caries, sex, education, income, hypertension, diabetes mellitus, osteoarthritis, arteriostenosis, myocardial infarction, comorbidity, fatigue, and ability to brush teeth.
RESULTS: The analyses showed that severe periodontal inflammation in at least three teeth at age 70 was marginally related to mortality during 21-year follow-up (crude hazard ratio (HR)=1.17, 95% confidence interval (CI)=0.91–1.78). The estimate increased slightly when adjusted for sex, income, fatigue, and smoking (adjusted HR=1.37, 95% CI=0.97–1.92). The estimates were attenuated when adjusted for the specific diseases, especially arteriostenosis and osteoarthritis.
CONCLUSION: Inflammation in the periodontium in early old age tends to be associated with mortality in older age. 相似文献
105.
Die diffusionsgewichtete Magnetresonanz Tomografie (DWI) stellt ein neues Verfahren dar, welches die Bildgebung von der einfachen Darstellung der Neuroanatomie um das Feld der funktionalen und physiologischen Prozesse erweitert. Im Gegensatz zur konventionellen MRT mi?t die DWI einen vollkommen anderen physiologischen Parameter. Der Bildkontrast h?ngt von Unterschieden in der Mikrobewegung (Diffusion) der Wassermoleküle im Hirngewebe ab. Daher kann die DWI pathologische Prozesse aufzeichnen, wo konventionelle T1- und T2-gewichtete MR Bilder unauff?llig bleiben. In der klinischen Routine hat sich die DWI bei der Diagnostik des akuten Schlaganfalls und des Traumas bew?hrt. durch die M?glichkeiten zwischen L?sionen mit zytotoxischem Oedem (verminderte Diffusion) und L?sionen mit vasogenem Oedem (vermehrte Diffusion) zu unterscheiden. Cerebrale Verletzungen k?nnen so früher nachgewiesen werden. Die Messung der Diffusion in verschiedenen Raumrichtungen erlaubt es eine Vielzahl funktionaler Karten zu erstellen. Die am h?ufigsten verwendeten Karten sind die des apparent diffusion coefficients (ADC) und der isotropen Diffusion. Zus?tzlich k?nnen Karten über anisotrope Diffusion berechnet werden. Diese sollen Auskunft über die Integrit?t und Lokalisation von Nervenbahnen geben. Diese funktional-anatomische Information wird wahrscheinlich in der Fühdiagnostik von prim?ren und sekund?ren Gewebeverletzungen unterschiedlicher Ursachen eine immer wichtigere Rolle spielen und k?nnte bestehende und zukünftige neuroprotektive Behandlungen leiten und validieren. 相似文献
106.
3-monochloropropane-1,2-diol (3-MCPD) is a member of a group of chemicals known as chloropropanols. It is found in many foods and food ingredients as a result of food processing. 3-MCPD is regarded as a rat carcinogen known to induce Leydig-cell and mammary gland tumours in males and kidney tumours in both genders. The aim of our study was to clarify the possible involvement of genotoxic mechanisms in 3-MCPD induced carcinogenicity at the target organ level. For that purpose, we evaluated DNA damages in selected target (kidneys and testes) and non-target (blood leukocytes, liver and bone marrow) male rat organs by the in vivo alkaline single cell gel electrophoresis (comet) assay, 3 and 24 h after 3-MCPD oral administration to Sprague-Dawley and Fisher 344 adult rats. 3-MCPD may be metabolised to a genotoxic intermediate, glycidol, whereas the predominant urinary metabolite in rats following 3-MCPD administration is beta-chlorolactic acid. Therefore, we also studied the DNA damaging effects of 3-MCPD and its metabolites, glycidol and beta-chlorolactic acid, in the in vitro comet assay on CHO cells. Our results show the absence of genotoxic potential of 3-MCPD in vivo in the target as well as in the non-target organs. Glycidol, the epoxide metabolite, induced DNA damages in CHO cells. beta-Chlorolactic acid, the main metabolite of 3-MCPD in rats, was shown to be devoid of DNA-damaging effects in vitro in mammalian cells. 相似文献
107.
Sorensen G Stoddard AM Youngstrom R Emmons K Barbeau E Khorasanizadeh F Levenstein C 《American journal of public health》2000,90(4):618-620
OBJECTIVES: This report describes local unions' positions on tobacco control initiatives and factors related to these positions. METHODS: A national random sample of local union leaders was surveyed by telephone. RESULTS: Forty-eight percent of local unions supported worksite smoking bans or restrictions, and only 8% opposed both a ban and a restriction. CONCLUSIONS: Support for tobacco control initiatives among local unions was higher than might be expected on the basis of previous evidence. Engaging unions in smoking policy formation is likely to contribute to the larger public health goal of reducing smoking and exposure to second-hand smoke among workers. 相似文献
108.
Camptothecins are DNA topoisomerase I-directed anti-tumour drugs with a novel mechanism of action. Topotecan (TPT), a hydrophilic derivative of camptothecin, is currently undergoing phase II clinical trials in small-cell lung cancer (SCLC). Human SCLC OC-NYH cells were made more than 6-fold resistant to topotecan by stepwise drug exposure and resistance was stable for 70 passages without drug. NYH/TPT cells had half the topoisomerase I level and activity of wild-type cells. However, no difference in camptothecin or topotecan inhibition of topoisomerase I-mediated DNA relaxation was found, indicating that the enzyme itself was unchanged in the resistant cell. In NYH/TPT cells, topoisomerase II alpha and beta levels were increased approximately 2-fold. Accordingly, the topoisomerase II-directed drug etoposide (VP-16) induced an increased number of DNA single-strand breaks in NYH/TPT cells. However, sensitivity to different topoisomerase II-targeting agents in NYH/TPT cells varied from increased to decreased, indicating a role for as yet unidentified factors acting on the pathway to cell death after topoisomerase II-induced DNA damage has occurred. Of 20 anti-cancer agents tested, only hydroxyurea showed marked collateral hypersensitivity in NYH/TPT cells. 相似文献
109.
W E Truog J C Jackson R J Badura G K Sorensen J H Murphy D E Woodrum 《American journal of diseases of children (1960)》1985,139(4):351-354
A review of all infants admitted to the two intensive care nurseries in Seattle from July 1, 1980, through Dec 31, 1981, was performed to evaluate the outcome of infants still requiring supplemental oxygen and/or mechanical ventilation at 1 month of age. Sixty-three infants were identified. Fifty-six infants survived to at least 2 years of age, including 11 of 13 in the subgroup of infants requiring 40% or more oxygen at 1 month of age. Eight (14%) of the 56 survivors have required prolonged rehospitalization for pneumonia or other respiratory illnesses in the first two years following birth. We conclude that the degree of gas exchange impairment assessed at 1 month of age does not predict ultimate outcome from neonatal chronic lung disease. 相似文献
110.
Sorensen Ilona Kryspin; Mortensen Alicja; Kristiansen Eva; van Kreijl Coen; Adamson Richard H.; Thorgeirsson Snorri S. 《Carcinogenesis》1996,17(10):2221-2227
The usefulness of transgenic Eµ-pim-1 mice over-expressingthe pim-1 oncogene in lymphoid tissues, as sensitive test organismswas studied in a short-term carcinogenicity study. The micewere fed standard diet Altromin 1314 supplemented either with0.03% 2-amino-1-methyl-6-phenylimidazo[4, 5-b]pyridine (PhIP)for 7 months or with 0.03% 2-amino-3-methylimidazo[4, 5-f] quinoline(IQ) for 6 months. PhIP and IQ are heterocyclic amines formedduring cooking of meat and fish and are mutagenic to bacteriaand cultured mammalian cells. PhIP is a potent mouse lymphomagen,while IQ is a liver carcinogen and also causes lung tumors andtumors of the forestomach in mice. We found that transgenicEµ-pim-1 mice are highly susceptible to PhIP induced lymphomagenesisbut do not respond to the IQ treatment. PhIP feeding of Eµ-pim-1mice not only increased the total number of T-cell lymphomasbut also decreased the latency time compared to either transgenicor wild-type controls. The effect was most pronounced in thetreated female Eµ-pim-1 mice, which showed a higher incidenceof PhIP induced T-cell lymphomas than transgenic males and astrongly reduced latency period after PhIP treatment comparedto non-transgenic mice. Our results suggest that the transgenicEµ-pim-1 mouse may be a useful model for short-term carcinogenicityscreening of potential genotoxic carcinogens having the lymphoidsystem as target tissue. The carcinogen IQ which does not havethe lymphoid system as a target was not recognized in this model. 相似文献