全文获取类型
收费全文 | 951篇 |
免费 | 61篇 |
国内免费 | 5篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 43篇 |
妇产科学 | 12篇 |
基础医学 | 110篇 |
口腔科学 | 17篇 |
临床医学 | 128篇 |
内科学 | 172篇 |
皮肤病学 | 35篇 |
神经病学 | 32篇 |
特种医学 | 130篇 |
外科学 | 56篇 |
综合类 | 39篇 |
预防医学 | 93篇 |
眼科学 | 4篇 |
药学 | 89篇 |
1篇 | |
肿瘤学 | 53篇 |
出版年
2023年 | 5篇 |
2022年 | 4篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 8篇 |
2018年 | 14篇 |
2017年 | 7篇 |
2016年 | 11篇 |
2015年 | 23篇 |
2014年 | 16篇 |
2013年 | 27篇 |
2012年 | 30篇 |
2011年 | 40篇 |
2010年 | 32篇 |
2009年 | 41篇 |
2008年 | 24篇 |
2007年 | 41篇 |
2006年 | 22篇 |
2005年 | 33篇 |
2004年 | 36篇 |
2003年 | 13篇 |
2002年 | 26篇 |
2001年 | 15篇 |
2000年 | 8篇 |
1999年 | 18篇 |
1998年 | 43篇 |
1997年 | 49篇 |
1996年 | 44篇 |
1995年 | 24篇 |
1994年 | 34篇 |
1993年 | 25篇 |
1992年 | 13篇 |
1991年 | 18篇 |
1990年 | 18篇 |
1989年 | 28篇 |
1988年 | 29篇 |
1987年 | 14篇 |
1986年 | 16篇 |
1985年 | 13篇 |
1984年 | 19篇 |
1983年 | 16篇 |
1982年 | 17篇 |
1981年 | 17篇 |
1980年 | 12篇 |
1979年 | 4篇 |
1978年 | 8篇 |
1976年 | 8篇 |
1975年 | 6篇 |
1974年 | 4篇 |
1972年 | 5篇 |
排序方式: 共有1017条查询结果,搜索用时 0 毫秒
21.
Irina Maljkovic Berry Melanie C. Melendrez Simon Pollett Katherine Figueroa Darunee Buddhari Chonticha Klungthong Ananda Nisalak Michael Panciera Butsaya Thaisomboonsuk Tao Li Tyghe G. Vallard Louis Macareo In-Kyu Yoon Stephen J. Thomas Timothy Endy Richard G. Jarman 《Emerging infectious diseases》2021,27(6):1637
Dengue control approaches are best informed by granular spatial epidemiology of these viruses, yet reconstruction of inter- and intra-household transmissions is limited when analyzing case count, serologic, or genomic consensus sequence data. To determine viral spread on a finer spatial scale, we extended phylogenomic discrete trait analyses to reconstructions of house-to-house transmissions within a prospective cluster study in Kamphaeng Phet, Thailand. For additional resolution and transmission confirmation, we mapped dengue intra-host single nucleotide variants on the taxa of these time-scaled phylogenies. This approach confirmed 19 household transmissions and revealed that dengue disperses an average of 70 m per day between households in these communities. We describe an evolutionary biology framework for the resolution of dengue transmissions that cannot be differentiated based on epidemiologic and consensus genome data alone. This framework can be used as a public health tool to inform control approaches and enable precise tracing of dengue transmissions. 相似文献
22.
Benjamin P. Haynes Michael Jarman Mitchell Dowsett Anshumala Mehta Per E. Lønning Leslie J. Griggs Alison Jones Trevor Powles Rob Stein R. Charles Coombes 《Cancer chemotherapy and pharmacology》1991,27(5):367-372
Summary The pyridylglutarimide 3-ethyl-3-(4-pyridyl)-piperidine-2,6-dione (PyG) is a novel inhibitor of aromatase that was shown to cause effective suppression of plasma oestradiol levels in postmenopausal patients. In four patients receiving oral doses of PyG (500 mg) twice daily for 3–4 days, oestradiol levels fell to 31.1%±6.3% of baseline values within 48 h and remained suppressed during treatment. Of a further six patients who received oral PyG (1 g) as a single dose, five had quantifiable oestradiol levels. Oestradiol suppression was sustained for 36 h and recovery correlated with a fall of PyG concentrations below a threshold value of ca. 2 g/ml. The pharmacokinetics of PyG were non-linear and, when fitted to the integrated Michaelis-Menten equation, yielded good parameter estimates forC
o (21.7±1.82 g/ml),K
m (2.66±0.68 g/ml) and Vmax (0.86±0.06 g ml–1 h–1). On subsequent repeated dosing with PyG, both theK
m (4.31±0.48 g/ml) and the Vmax (1.83±0.13 g ml–1 h–1) values increased and recovery from oestradiol suppression was more rapid, indicating that PyG induces its own metabolism.Abbreviations PyG
3-ethyl-3-(4-pyridyl)piperidine-2,6-dione
- AG
aminoglutethimide
- CSCC
cholesterol side-chain cleavage
- HPLC
high-performance liquid chromatography
- AUC
area under the concentration versus time curve
This study was supported in part by grants to the Institute of Cancer Research (Royal Cancer Hospital) from the Cancer Research Campaign and Medical Research Council 相似文献
23.
OBJECTIVES: To study the efficacy of otoacoustic emissions (OAEs) as a screening test for hearing impairment in children with acute bacterial meningitis. Hearing tests were performed before discharge from the hospital in an attempt to improve coverage and avoid delays in the diagnosis of postmeningitic hearing loss. METHODS: Children with bacterial meningitis were recruited from 21 centers. In the 48 hours before discharge from the hospital, all patients underwent a thorough audiologic assessment consisting of transient evoked OAEs, auditory brainstem responses (ABRs), otoscopy, and tympanometry. Hearing loss was defined as ABR threshold >/=30 dB. The results of OAE screening were compared with the gold standard of ABR threshold. RESULTS: Of 124 children recruited, we were able to perform both OAEs and ABRs on 110 children. Seven (6.3%) of the 110 children had ABR threshold >/=30 dB; 2 had sensorineural hearing loss and 5 had conductive hearing loss. At follow-up, hearing loss persisted in both cases of sensorineural hearing loss and no new cases were identified. All 7 children with hearing loss failed the OAE screening test. Ninety-four children with normal hearing thresholds passed the test, and 9 failed. Thus, the screening test had a sensitivity of 1.00 (95% confidence interval, 0.59 to 1.00), a specificity of 0.91 (0.85 to 0.97), a positive predictive value of 0. 44 (0.20 to 0.70), and a negative predictive value of 1.00 (0.96 to 1.00). CONCLUSIONS: OAE screening in children recovering from meningitis was found to be feasible and effective. The test was highly sensitive and reasonably specific. Inpatient OAE screening should allow early diagnosis of postmeningitic hearing loss and prompt auditory rehabilitation. 相似文献
24.
Iron-overload diseases frequently develop hepatocellular carcinoma. The
genotoxic mechanism whereby iron is involved in hepatocarcinogenesis might
involve an oxidative process via the intermediate production of reactive
oxygen species. This was presently investigated by examining kinetics of
formation and repair of DNA base lesions in primary rat hepatocyte cultures
supplemented with the iron chelate, ferric nitrilotriacetate Fe-NTA (10 and
100 microM). Seven DNA base oxidation products have been identified in DNA
extracts by gas chromatography- mass spectrometry, which showed a
predominance of oxidized-purines (8- oxo-guanine, xanthine, fapy-adenine,
2-oxo-adenine) above oxidized pyrimidines (5-OHMe-uracil, 5-OH-uracil,
5-OH-cytosine) in control cultures. All these DNA oxidation products
revealed a significant dose- dependent increase at 4 to 48 h after Fe-NTA
supplementation, among which fapy-adenine showed the highest increase and
5-OH-cytosine was the least prominent. Involvement of iron in this
oxidative process was established by a correlation between extent in DNA
oxidation and intracellular level of toxic low molecular weight iron. DNA
excision- repair activity was estimated by release of DNA oxidation
products in culture medium. All the seven DNA oxidation products were
detected in the medium of control cultures and showed basal repair
activity. This DNA repair activity was increased in a time- and
dose-dependent fashion with Fe-NTA. Oxidized-pyrimidines, among which was
5-OHMe-Uracil, were preferentially repaired, which explains the low levels
detected in oxidized DNA. Since oxidized bases substantially differed from
one another in terms of excision rates from cellular DNA, specific
excision- repair enzymes might be involved. Our findings, however,
demonstrate that even though DNA repair pathways were activated in
iron-loaded hepatocyte cultures, these processes were not stimulated enough
to prevent an accumulation of highly mutagenic DNA oxidative products in
genomic DNA. The resulting genotoxic effect of Fe-NTA might be relevant in
understanding the hepatocarcinogenic evolution of iron-overload diseases.
相似文献
25.
26.
27.
28.
29.
Benjamin R. Kipp PhD CT MP Fabiola Medeiros MD Michael B. Campion BS Tammy J. Distad CT Lisa M. Peterson CLSp Gary L. Keeney MD Kevin C. Halling MD PhD Amy C. Clayton MD 《Cancer cytopathology》2008,114(4):228-235
BACKGROUND.
Endometrial cytology sampling devices for direct uterine sampling have been shown in previous studies to be a reliable and relatively painless method for detecting endometrial lesions. The purpose of the current study was to determine the performance characteristics of endometrial cytology for the detection of malignancy and atypical hyperplasia using liquid‐based cytology specimens collected with the Tao brush sampler.METHODS.
Brushings of the endometrial cavity were obtained from 139 hysterectomy specimens before routine histopathologic evaluation. Cytology specimens were fixed in PreservCyt and processed using ThinPrep technology. Cytology diagnoses were classified as nondiagnostic, negative, atypical, or positive for malignancy. Histopathologic findings were used as the gold standard for determining the performance characteristics of cytology.RESULTS.
Histopathologic results from the 139 patients included 81 (58%) endometrial cancers, 7 (5%) complex hyperplasias with atypia, 2 (1%) complex hyperplasias without atypia, and 49 (35%) patients with benign histology. The number of specimens diagnosed cytologically as positive, atypical, negative, or nondiagnostic was 60 (43%), 40 (29%), 37 (27%), and 2 (1%) specimens, respectively. The overall sensitivity and specificity of cytology for detecting endometrial cancer and atypical hyperplasia were 95% and 66% when atypical cytology specimens were considered positive.CONCLUSIONS.
The results of the current study indicate that direct endometrial sampling by liquid‐based endometrial cytology collected with the Tao brush sampler produces specimens that contain cellular material that may be identified as endometrial cancer or atypical hyperplasia. Both atypical and positive cytology diagnoses are indicators for triage to more specific methods of diagnosis. Cancer (Cancer Cytopathol) 2008. © 2008 American Cancer Society 相似文献30.
Jens W. Levy Piyarat Suntarattiwong James M. Simmerman Richard G. Jarman Kara Johnson Sonja J. Olsen Tawee Chotpitayasunondh 《Influenza and other respiratory viruses》2014,8(1):13-16
Within a hand‐washing clinical trial, we evaluated factors associated with fomite contamination in households with an influenza‐infected child. Influenza virus RNA contamination was higher in households with low absolute humidity and in control households, suggesting that hand washing reduces surface contamination. 相似文献