全文获取类型
收费全文 | 3900篇 |
免费 | 238篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 54篇 |
儿科学 | 100篇 |
妇产科学 | 32篇 |
基础医学 | 523篇 |
口腔科学 | 68篇 |
临床医学 | 475篇 |
内科学 | 697篇 |
皮肤病学 | 30篇 |
神经病学 | 393篇 |
特种医学 | 140篇 |
外科学 | 535篇 |
综合类 | 42篇 |
一般理论 | 4篇 |
预防医学 | 483篇 |
眼科学 | 53篇 |
药学 | 307篇 |
中国医学 | 4篇 |
肿瘤学 | 206篇 |
出版年
2023年 | 21篇 |
2022年 | 33篇 |
2021年 | 77篇 |
2020年 | 61篇 |
2019年 | 75篇 |
2018年 | 73篇 |
2017年 | 56篇 |
2016年 | 83篇 |
2015年 | 95篇 |
2014年 | 154篇 |
2013年 | 187篇 |
2012年 | 284篇 |
2011年 | 299篇 |
2010年 | 150篇 |
2009年 | 148篇 |
2008年 | 238篇 |
2007年 | 314篇 |
2006年 | 266篇 |
2005年 | 244篇 |
2004年 | 229篇 |
2003年 | 232篇 |
2002年 | 186篇 |
2001年 | 44篇 |
2000年 | 31篇 |
1999年 | 29篇 |
1998年 | 48篇 |
1997年 | 36篇 |
1996年 | 40篇 |
1995年 | 34篇 |
1994年 | 17篇 |
1993年 | 25篇 |
1992年 | 30篇 |
1991年 | 16篇 |
1990年 | 16篇 |
1989年 | 15篇 |
1988年 | 22篇 |
1987年 | 23篇 |
1986年 | 18篇 |
1985年 | 29篇 |
1984年 | 23篇 |
1983年 | 13篇 |
1982年 | 14篇 |
1981年 | 14篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1977年 | 8篇 |
1976年 | 8篇 |
1974年 | 10篇 |
1973年 | 7篇 |
1972年 | 11篇 |
排序方式: 共有4146条查询结果,搜索用时 15 毫秒
21.
Martin RA Grange DK Zehnbauer B Debaun MR 《American journal of medical genetics. Part A》2005,(2):129-131
We performed LIT1 and H19 methylation studies on 27 children with isolated hemihyperplasia (IH). Eight children (29.6%) had a defect in methylation of one or both of these alleles, supporting our hypothesis that these epigenetic changes can result in a phenotype distinct from typical Beckwith-Wiedemann syndrome. 相似文献
22.
A monoclonal antibody (Mab D12A4) was used to follow the genesis and fate of rhoptries from early first-generation merogony
through second-generation merozoites of the rat coccidium Eimeria nieschulzi. The epitope recognized by Mab D12A4 belongs to a 22-kDa protein which can be localized first in developing meronts 25 h post-infection.
Early rhoptries appear as distinct granules in the cytoplasm of developing meronts and elongate into mature organelles before
merozoite release. The 22-kDa protein is found in the parasitophorous vacuole after host cell invasion. Western blotting and
immunofluorescence showed that the 22-kDa rhoptry protein is expressed in schizonts and merozoites but not in sporozoites.
Received: 9 August 1997 / Accepted: 14 October 1997 相似文献
23.
Intranasal vaccination induces protective immunity against intranasal infection with virulent Francisella tularensis biovar A 下载免费PDF全文
The inhalation of Francisella tularensis biovar A causes pneumonic tularemia associated with high morbidity and mortality rates in humans. Exposure to F. tularensis usually occurs by accident, but there is increasing awareness that F. tularensis may be deliberately released in an act of bioterrorism or war. The development of a vaccine against pneumonic tularemia has been limited by a lack of information regarding the mechanisms required to protect against this disease. Vaccine models for F. tularensis in inbred mice would facilitate investigations of the protective mechanisms and significantly enhance vaccine development. Intranasal vaccination with the attenuated live vaccine strain (LVS) of F. tularensis reproducibly protected BALB/c mice, but not C57BL/6 mice, against intranasal and subcutaneous challenges with a virulent clinical isolate of F. tularensis biovar A (NMFTA1). The resistance of LVS-vaccinated BALB/c mice to intranasal NMFTA1 challenge was increased 100-fold by boosting with live NMFTA1 but not with LVS. The protective response was specific for F. tularensis and required both CD4 and CD8 T cells. The vaccinated mice appeared outwardly healthy for more than 2 months after NMFTA1 challenge, even though NMFTA1 was recovered from more than half of the vaccinated mice. These results show that intranasal vaccination induces immunity that protects BALB/c mice from intranasal infection by F. tularensis biovar A. 相似文献
24.
Treiber FA Turner JR Davis H Strong WB 《International journal of behavioral medicine》1997,4(4):278-291
Two hundred forty-six children (96 Whites, of whom 51 were mates; 150 African- Americans, of whom 69 were males) with a familial
history of essential hypertension (EH) were re-evaluated 5 years after an initial evaluation. During the initial visit, anthropometric,
demographic, and resting cardiovascular (CV) parameters (designated initial baseline levels) were assessed. These CV parameters
(systolic and diastolic blood pressure [BP], heart rate, cardiac output index [CI], and total peripheral resistance index
[TPRI]) were also measured during postural challenge, a video game challenge, and a cold pressor task. At follow-up, resting
CV parameters were again evaluated, and designated as follow-up resting levels. Moderate temporal stability (r range = .43-.56) was observed for all resting CV parameters. Mean stress responses for each CV parameter for all 3 stressors
during the initial visit were positively related to the respective CV follow-up resting level. BP stress responses to postural
change and video game challenge were found to be significant independent predictors of future resting BP after controlling
for standard EH risk factors. Follow-up resting CI was not predicted by any stress responses, whereas follow-up resting TPRI
was predicted by TPRI responses to the video game after controlling for standard EH risk Factors. These results contrast with
those from an earlier 1-year follow-up. where stress responses for neither CI nor TPRI predicted follow-up resting levels.
It appears that, as children get older. TPRI stress responses play a stronger role in vasoconstrictive function.
This research was supported by National Institutes of Health Grant HL41781. 相似文献
25.
We conducted a two-part study of age and latent inhibition in the rat. In the first part of the study, rats given odor-shock pairings at 23 or 75 days of age exhibited a potentiated startle response in the presence of the odor the following day. This effect did not occur in rats trained at 16 or 20 days of age. Odor pre-exposure on the day prior to conditioning markedly reduced the odor potentiation of startle effect in 23- and 75-day-old rats but had no effect in 16 and 20-day-olds. In the second part of the study, rats were pre-exposed to the odor at 16 or 20 days of age and then conditioned at 23 days of age. When tested the day after conditioning, these pre-exposed rats exhibited a disruption in the odor potentiation of startle effect. We compare our results with other studies of latent inhibition, and with recent studies on whether conditioned responses are appropriate to the animal's age at training or their age at test. 相似文献
26.
This paper describes a methodology to assess health/medical informatics graduate-level education curricula. The authors used the Certified Professional in Healthcare Information Management Systems (CPHIMS) exam objectives published by the Healthcare Information and Management Systems Society (HIMSS) as the basis for their assessment. The authors compared the 69 CPHIMS exam objectives against four health/medical informatics program course objectives as stated in the selected program's online graduate catalog. Results showed that the two programs with management as a focus addressed the majority (67 and 59%) of the CPHIMS objectives within core and elective courses combined. Overall, the other two programs addressed closer to a third of the CPHIMS objectives (36 and 32%). This methodology could prove to be useful in assisting students interested in graduate-level training programs with a tool by which to measure the congruence of the curricula of different programs with the mission of the programs and with their own professional interests. 相似文献
27.
Improved characterization of Theileria parva isolates using the polymerase chain reaction and oligonucleotide probes 总被引:2,自引:0,他引:2
B Allsopp M Carrington H Baylis S Sohal T Dolan K Iams 《Molecular and biochemical parasitology》1989,35(2):137-147
Theileria parva DNA was purified from piroplasms isolated from cattle infected with 5 different East African isolates of the parasite, including the East Coast fever reference stock T. p. parva Muguga. Total cellular DNA was prepared from T. parva schizont-infected bovine lymphoblastoid cell cultures (11 isolates). Two probes, previously isolated from T. p. parva Muguga repetitive genomic DNA, were hybridized to restriction digests; closely similar restriction fragment length polymorphism (RFLP) patterns were produced, and no two isolates had the same RFLP pattern. The DNA sequences of probe PMB3, two further copies of the repeated sequence from T. p. parva Muguga, and homologous regions from T. p. parva Kiambu 4 and T. p. lawrencei 3081, were determined. Oligonucleotides were synthesized corresponding to two conserved sections flanking a region which varied between isolates. These oligonucleotides were used as primers in the polymerase chain reaction to amplify the variable region. Further oligonucleotides corresponding to sequences in this variable region were able to distinguish between isolates and no sample hybridized to both oligonucleotides. This is the first unequivocal plus/minus discrimination between groups of isolates to be achieved for T. parva. 相似文献
28.
Rick Galli Linda Merrick Michel Friesenhahn Rainer Ziermann 《Journal of clinical virology》2005,34(4):245-252
BACKGROUND: Plasma human immunodeficiency virus type 1 (HIV-1) RNA level is an important parameter for patient management, yet viral load assays from different manufacturers are not standardized. OBJECTIVES AND STUDY DESIGN: In this study, we evaluated the concordance between test results obtained for 1,000 plasma specimens collected from HIV-1-infected individuals measured with the VERSANT HIV-1 RNA 3.0 assay (bDNA) and the COBAS AMPLICOR HIV-1 MONITOR 1.5 test (PCR). We compared viral load values obtained by each of these assays throughout their dynamic ranges, with particular focus on samples with low viral load (i.e. 50-250 copies/mL), and calculated the estimated distribution of distinct plasma viral load levels for the entire study population modeled from the data observed in the study. RESULTS: We found that these two assays show excellent agreement, with a correlation (R(2)) of 0.957 and a slope of 1.004. The mean difference in viral load values between the two assays was less than 0.10-log(10) throughout the dynamic range and 98.2% of all samples had bDNA and PCR results within 0.5-log(10) of each other, a difference that is within the range considered to be a minimal change in plasma viremia. Moreover, the two assays show very similar results across all assay ranges tested. The estimated prevalence of samples with results <50 copies/mL, 50-250 copies/mL, and 250-500,000 copies/mL were 41.6%, 7.7%, and 49.7%, respectively, by the bDNA assay, and 42.4%, 6.9%, and 50.7%, respectively, by the PCR assay. CONCLUSION: Based on our findings from 1,000 clinical specimens, we do not see the need to re-establish a baseline value or apply a conversion factor when switching from one assay to the other. Since the majority of our patient population likely is infected with subtype B virus, it is unclear if our findings will apply to other patient populations with a greater incidence of infection with non-B subtypes. 相似文献
29.
30.