全文获取类型
收费全文 | 7390篇 |
免费 | 663篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 54篇 |
儿科学 | 196篇 |
妇产科学 | 105篇 |
基础医学 | 875篇 |
口腔科学 | 155篇 |
临床医学 | 816篇 |
内科学 | 1503篇 |
皮肤病学 | 96篇 |
神经病学 | 439篇 |
特种医学 | 413篇 |
外科学 | 1020篇 |
综合类 | 148篇 |
一般理论 | 1篇 |
预防医学 | 856篇 |
眼科学 | 95篇 |
药学 | 595篇 |
中国医学 | 4篇 |
肿瘤学 | 692篇 |
出版年
2023年 | 49篇 |
2021年 | 106篇 |
2020年 | 73篇 |
2019年 | 104篇 |
2018年 | 134篇 |
2017年 | 103篇 |
2016年 | 126篇 |
2015年 | 113篇 |
2014年 | 176篇 |
2013年 | 256篇 |
2012年 | 357篇 |
2011年 | 338篇 |
2010年 | 210篇 |
2009年 | 179篇 |
2008年 | 322篇 |
2007年 | 358篇 |
2006年 | 321篇 |
2005年 | 287篇 |
2004年 | 292篇 |
2003年 | 265篇 |
2002年 | 269篇 |
2001年 | 260篇 |
2000年 | 281篇 |
1999年 | 202篇 |
1998年 | 102篇 |
1997年 | 82篇 |
1996年 | 70篇 |
1995年 | 93篇 |
1994年 | 85篇 |
1993年 | 82篇 |
1992年 | 185篇 |
1991年 | 163篇 |
1990年 | 153篇 |
1989年 | 142篇 |
1988年 | 182篇 |
1987年 | 148篇 |
1986年 | 112篇 |
1985年 | 136篇 |
1984年 | 98篇 |
1983年 | 96篇 |
1982年 | 62篇 |
1981年 | 50篇 |
1979年 | 93篇 |
1978年 | 68篇 |
1977年 | 46篇 |
1976年 | 50篇 |
1974年 | 55篇 |
1973年 | 62篇 |
1971年 | 42篇 |
1970年 | 43篇 |
排序方式: 共有8063条查询结果,搜索用时 15 毫秒
91.
Comparative genomic hybridization provides new insights into the molecular taxonomy of the Saccharomyces sensu stricto complex 下载免费PDF全文
Edwards-Ingram LC Gent ME Hoyle DC Hayes A Stateva LI Oliver SG 《Genome research》2004,14(6):1043-1051
The science of taxonomy is constantly improving as new techniques are developed. Current practice is to construct phylogenetic trees based on the analysis of the DNA sequence of single genes, or parts of single genes. However, this approach has recently been brought into question as several tree topologies may be produced for the same clade when the sequences for various different genes are used. The availability of complete genome sequences for several organisms has seen the adoption of microarray technology to construct molecular phylogenies of bacteria, based on all of the genes. Similar techniques have been used to reveal the relationships between different strains of the yeast Saccharomyces cerevisiae. We have exploited microarray technology to construct a molecular phylogeny for the Saccharomyces sensu stricto complex of yeast species, which is based on all of the protein-encoding genes revealed by the complete genome sequence of the paradigmatic species, S. cerevisiae. We also analyze different strains of S. cerevisiae itself, as well as the putative species S. boulardii. We show that in addition to the phylogeny produced, we can identify and analyze individual ORF traits and interpret the results to give a detailed explanation of evolutionary events underlying the phylogeny. 相似文献
92.
Biolistic (biological ballistic) and protoplast-mediated procedures were compared as methods for transforming strains of Gliocladium virens and Trichoderma harzianum. For biolistic transformation, conidia were bombarded using a helium-driven biolistic device to accelerate M5 tungsten particles coated with plasmid or genomic DNA. DNA from either source contained a bacterial hygromycin B resistance gene (hygB) as a dominant selectable marker. The same sources of DNA were also used to transform protoplasts using a standard polyethylene glycol-CaCl2 protoplast fusion protocol. Hygromycin B-resistant (HygBR) transformants were recovered from all strains, methods, and DNA sources except for genomic DNA used with the protoplast method. The biolistic procedure was technically simpler, and increased transformation frequency and genetic stability in the progeny as compared with the protoplast-mediated transformation. Southern analysis of homokaryotic HygBR progenies showed that the transforming sequences were integrated into the genome of the recipient strains, and apparently were methylated. This is the first study presenting detailed results on biolistic transformation of a filamentous fungus. 相似文献
93.
Experimental Chagas'' disease: kinetics of lymphocyte responses and immunological control of the transition from acute to chronic Trypanosoma cruzi infection. 总被引:8,自引:3,他引:8 下载免费PDF全文
The responses of spleen cells from mice infected with Trypanosoma cruzi to stimulation with T (concanavalin A and phytohemagglutinin) or B (lipopolysaccharide) cell-specific mitogens were monitored during the acute, transition, and chronic states of the disease. A marked reduction in the responses of infected mouse cells with respect to those of uninfected animals was observed during the acute stage, regardless of whether or not the infective dose was lethal. Reduced or absent responses were recorded with suboptimal, optimal, and supraoptimal concentrations of the mitogens. Normal levels of responsiveness to concanavalin A, phytohemagglutinin, and lipopolysaccharide were observed during the chronic stage of the disease. The trend of return to normal responses was initiated around day 40 after infection with 25 parasites. At this time, a marked decline in parasitemia levels, cessation of mortality, and disappearance of visible signs of disease began to be observed defining the transition stage that precedes establishment of chronicity. T cell levels of the spleen were markedly reduced during the acute period and returned during the chronic phase. Instead, absolute levels of B cells were significantly increased during the acute period but also normalize in the chronic phase. Immunosuppression of chronically infected mice with cyclophosphamide led to a temporary return to acute infection-type conditions, even in animals with undetectable levels of parasitemia before treatment. These results suggest that reduced T cell responses during acute experimental Chagas' disease might in part to be due to depletion of the T cell compartment. Decreased B cell responses in the presence of significant numbers of B lymphocytes implies a suppressive phenomenon, B cell alteration, or a combination of both possibilities. Recrudescence of the disease after immunosuppression with cyclophosphamide suggests that immunological mechanisms play an important role, not only in the gain of control over T. cruzi infected by the host but also in the maintenance of the chronic status. 相似文献
94.
S G Siris A Rifkin G T Reardon J Endicott D H Pereira R Hayes E Casey 《The American journal of psychiatry》1984,141(10):1254-1257
The authors evaluated 20 patients, diagnosed by Research Diagnostic Criteria after 1 week of hospitalization as having schizophrenia, weekly throughout their hospitalization. Four patients developed syndromes of depression after resolution of their psychoses: three manifesting a "minor" and one a "major" postpsychotic depressive syndrome. Four other patients went on to develop syndromes equivalent to major depression at a time when they were still actively psychotic, and their cross-sectional diagnoses were therefore changed to schizoaffective disorder, depressed type. The authors discuss the implications of these findings for diagnosis. 相似文献
95.
María Jesús Fernández Aceñero MD PhD Cristina Díaz del Arco CDdA MD Carme Dinarés CD MD PhD Tania Labiano TL MD Eva Tejerina ET MD PhD Mª José Bernabé MJ B MD Elena Forcen EF MD Melchor Saiz-Pardo MSP MD Pablo Pérez PP MD Maria D. Lozano MDL MD PhD 《Diagnostic cytopathology》2023,51(1):26-35
Lung carcinoma remains one of the most frequent and aggressive human neoplasms. Fortunately, in the last decades, the increasing knowledge of the molecular mechanisms leading to cancer development has allowed the use of targeted therapies with improvement of prognosis in many patients. Clinical management has also changed after the introduction of endobronchialultrasonographic bronchoscopy that allows a conservative staging of lung tumors, avoiding the need of mediastinoscopy for lymph node staging. Lung pathologists and cytopathologists are facing the challenge of giving the more comprehensive prognostic and predictive information with ever smaller tissue or cytological samples. The aim of this review is to summarize the molecular testing for non-small cell lung carcinoma and how pathologists can contribute to the patient's outcome with a conscious management of biological samples. 相似文献
96.
97.
Sarah Duncan-Park Claire Dunphy Jacqueline Becker Christine D’Urso Rachel Annunziato Joshua Blatter Carol Conrad Samuel B. Goldfarb Don Hayes Jr. Ernestina Melicoff Marc Schecter Gary Visner Brian Armstrong Hyunsook Chin Karen Kesler Nikki M. Williams Jonah N. Odim Stuart C. Sweet Lara Danziger-Isakov Eyal Shemesh 《American journal of transplantation》2021,21(9):3112-3122
Remote interventions are increasingly used in transplant medicine but have rarely been rigorously evaluated. We investigated a remote intervention targeting immunosuppressant management in pediatric lung transplant recipients. Patients were recruited from a larger multisite trial if they had a Medication Level Variability Index (MLVI) ≥2.0, indicating worrisome tacrolimus level fluctuation. The manualized intervention included three weekly phone calls and regular follow-up calls. A comparison group included patients who met enrollment criteria after the subprotocol ended. Outcomes were defined before the intent-to-treat analysis. Feasibility was defined as ≥50% of participants completing the weekly calls. MLVI was compared pre- and 180 days postenrollment and between intervention and comparison groups. Of 18 eligible patients, 15 enrolled. Seven additional patients served as the comparison. Seventy-five percent of participants completed ≥3 weekly calls; average time on protocol was 257.7 days. Average intervention group MLVI was significantly lower (indicating improved blood level stability) at 180 days postenrollment (2.9 ± 1.29) compared with pre-enrollment (4.6 ± 2.10), p = .02. At 180 days, MLVI decreased by 1.6 points in the intervention group but increased by 0.6 in the comparison group (p = .054). Participants successfully engaged in a long-term remote intervention, and their medication blood levels stabilized. NCT02266888. 相似文献
98.
Alejandro Azofeifa Diana Valencia Carmen J. Rodriguez Maritza Cruz Devin Hayes Edn Montaez-Bez Betzaida Tejada-Vera Joshua E. Villafae-Delgado Jessica J. Cabrera Miguel Valencia-Prado 《Public health reports (Washington, D.C. : 1974)》2021,136(3):354
ObjectivesUsing the Council of State and Territorial Epidemiologists (CSTE) classification guidelines, we characterized coronavirus disease 2019 (COVID-19)–associated confirmed and probable deaths in Puerto Rico during March–July 2020. We also estimated the total number of possible deaths due to COVID-19 in Puerto Rico during the same period.MethodsWe described data on COVID-19–associated mortality, in which the lower bound was the sum of confirmed and probable COVID-19 deaths and the upper bound was excess mortality, estimated as the difference between observed deaths and average expected deaths. We obtained data from the Puerto Rico Department of Health COVID-19 Mortality Surveillance System, the Centers for Disease Control and Prevention’s National Electronic Disease Surveillance System Base System, and the National Center for Health Statistics.ResultsDuring March–July 2020, 225 COVID-19–associated deaths were identified in Puerto Rico (119 confirmed deaths and 106 probable deaths). The median age of decedents was 73 (interquartile range, 59-83); 60 (26.7%) deaths occurred in the Metropolitana region, and 140 (62.2%) deaths occurred among men. Of the 225 decedents, 180 (83.6%) had been hospitalized and 93 (41.3%) had required mechanical ventilation. Influenza and pneumonia (48.0%), sepsis (28.9%), and respiratory failure (27.1%) were the most common conditions contributing to COVID-19 deaths based on death certificates. Based on excess mortality calculations, as many as 638 COVID-19–associated deaths could have occurred during the study period, up to 413 more COVID-19–associated deaths than originally reported.ConclusionsIncluding probable deaths per the CSTE guidelines and monitoring all-cause excess mortality can lead to a better estimation of COVID-19–associated deaths and serve as a model to enhance mortality surveillance in other US jurisdictions. 相似文献
99.
Lario Viljoen Virginia A. Bond Lindsey J. Reynolds Constance Mubekapi‐Musadaidzwa Dzunisani Baloyi Rhoda Ndubani Anne Stangl Janet Seeley Triantafyllos Pliakas Peter Bock Sarah Fidler Richard Hayes Helen Ayles James R. Hargreaves Graeme Hoddinott 《Sociology of health & illness》2021,43(1):167-185
Despite continued development of effective HIV treatment, expanded access to care and advances in prevention modalities, HIV‐related stigma persists. We examine how, in the context of a universal HIV‐testing and treatment trial in South Africa and Zambia, increased availability of HIV services influenced conceptualisations of HIV. Using qualitative data, we explore people’s stigma‐related experiences of living in ‘intervention’ and ‘control’ study communities. We conducted exploratory data analysis from a qualitative cohort of 150 households in 13 study communities, collected between 2016 and 2018. We found that increased availability of HIV‐testing services influenced conceptualisations of HIV as normative (non‐exceptional) and the visibility of people living with HIV (PLHIV) in household and community spaces impacted opportunities for stigma. There was a shift in community narratives towards individual responsibility to take up (assumingly) widely available service – for PLHIV to take care of their own health and to prevent onward transmission. Based on empirical data, we show that, despite a growing acceptance of HIV‐related testing services, anticipated stigma persists through the mechanism of shifting responsibilisation. To mitigate the responsibilisation of PLHIV, heath implementers need to adapt anti‐stigma messaging and especially focus on anticipated stigma. 相似文献
100.
Health departments everywhere are struggling to balance shrinking resources against increasing requests for services. According to the Institute of Medicine report, The Future of Public Health, one of the barriers to solving public health problems is "... disjointed decision-making without necessary data and knowledge ..." (p. 107). Leadership of the Middle Tennessee Region of the Tennessee Department of Health have addressed this issue by developing a practical, usable data base from which to consider the needs and resources of the region. 相似文献