全文获取类型
收费全文 | 12187篇 |
免费 | 1027篇 |
国内免费 | 30篇 |
专业分类
耳鼻咽喉 | 139篇 |
儿科学 | 526篇 |
妇产科学 | 329篇 |
基础医学 | 1636篇 |
口腔科学 | 143篇 |
临床医学 | 1962篇 |
内科学 | 2241篇 |
皮肤病学 | 157篇 |
神经病学 | 1222篇 |
特种医学 | 203篇 |
外国民族医学 | 2篇 |
外科学 | 929篇 |
综合类 | 153篇 |
一般理论 | 18篇 |
预防医学 | 1899篇 |
眼科学 | 182篇 |
药学 | 624篇 |
中国医学 | 16篇 |
肿瘤学 | 863篇 |
出版年
2024年 | 26篇 |
2023年 | 159篇 |
2022年 | 204篇 |
2021年 | 377篇 |
2020年 | 283篇 |
2019年 | 433篇 |
2018年 | 437篇 |
2017年 | 379篇 |
2016年 | 341篇 |
2015年 | 387篇 |
2014年 | 491篇 |
2013年 | 726篇 |
2012年 | 982篇 |
2011年 | 977篇 |
2010年 | 542篇 |
2009年 | 454篇 |
2008年 | 768篇 |
2007年 | 827篇 |
2006年 | 746篇 |
2005年 | 652篇 |
2004年 | 630篇 |
2003年 | 576篇 |
2002年 | 542篇 |
2001年 | 92篇 |
2000年 | 56篇 |
1999年 | 64篇 |
1998年 | 110篇 |
1997年 | 76篇 |
1996年 | 75篇 |
1995年 | 62篇 |
1994年 | 60篇 |
1993年 | 41篇 |
1992年 | 36篇 |
1991年 | 44篇 |
1990年 | 24篇 |
1989年 | 36篇 |
1988年 | 30篇 |
1987年 | 31篇 |
1986年 | 24篇 |
1985年 | 22篇 |
1984年 | 29篇 |
1983年 | 20篇 |
1982年 | 28篇 |
1981年 | 24篇 |
1980年 | 31篇 |
1979年 | 13篇 |
1978年 | 12篇 |
1977年 | 16篇 |
1976年 | 22篇 |
1974年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Summary Replication of a CELO large plaque (LP) mutant and that of its wild type small plaque (SP) parent was studied in the chorioallantoic membrane (CAM) and in the amnion of 11-day-old embryos. Although both strains produced essentially the same amount of virus in the tissue fluids, they differed in their rates of replication. Replication of the SP parent was maximal in the CAM 24 to 48 hours before that of the LP mutant. Whereas inclusions were observed in SP inoculated CAM 48 hours PI and were present during the course of study; LP inclusions were rare at 72 hours PI and thereafter; LP inclusions were seen at 72 hours PI. Fewer SP than LP particles were required to produce inclusions. No inclusions were seen in sections of the trachea and liver removed at 96 hours PI from embryos inoculated via the amniotic sac with LP and SP virus.Contribution 1466 of the Rhode Island Agriculture Experimental Station. 相似文献
42.
Antibiotic prescribing and admissions with major suppurative complications of respiratory tract infections: a data linkage study. 下载免费PDF全文
Paul Little Louise Watson Stephen Morgan Ian Williamson 《The British journal of general practice》2002,52(476):187-90,193
BACKGROUND: Systematic reviews of antibiotic treatment of common acute respiratory tract infections (RTIs) suggest modest symptomatic benefit, but provide limited evidence that prescribing prevents complications. AIM: To assess the relationship between penicillin prescribing (the most commonly used group of antibiotics for RTIs) and hospital admission with complications. DESIGN OF STUDY: Data linkage study. SETTING: Ninety-six health authorities of England for the year 1997-1998. METHOD: Hospital admissions related to RTIs were linked with prescribing analysis and cost (PACT) data. RESULTS: There was close correlation between items of penicillin use and total antibiotic use (r = 0.96). After controlling for SMR, age, sex, and Townsend score, a one-unit increase in penicillin use (items dispensed per capita) was associated with a reduction in annual incidence per 10,000 of admissions for quinsy (-3.55 admissions, 95% confidence interval [CI] = -6.85 to -0.26), and mastoiditis (square root of incidence of admissions = -1.05, 95% CI = -1.82 to -0.27). This does not represent lower referral thresholds among higher prescribers as higher prescribing was associated with more admissions for tonsillectomy and overall admissions. Increasing prescribing by 2000 items of penicillin for a practice of 10,000 patients could possibly prevent one admission for either mastoiditis or quinsy. CONCLUSION: Higher antibiotic prescribing is associated with significantly fewer admissions with major complications. However, the overall size of the effect is modest and it is difficult to advocate an overall increase in prescribing to prevent complications. Future research should concentrate on finding better methods of targeting antibiotics to individuals at risk of poor outcome. 相似文献
43.
D. Amat Prof. J. P. Camilleri G. Feldmann F. Bloch A. Duboust J. Bedrossian 《Virchows Archiv : an international journal of pathology》1981,391(2):153-163
Summary A prospective series of 45 liver biopsies taken from 22 renal transplant patients was investigated for the presence of hepatitis B antigen core (HBc) and surface (HBs) components by electron microscopy. At the time of each biopsy serum HBs Ag was sought by radioimmunoassay. Sections were taken for the detection of HBs Ag by immunofluorescence.In seropositive patients, intravesicular tubular structures resembling HBs Ag were found in 61% of biopsies while the intranuclear core HBc was present in 69%. No correlation could be made between the ultrastructural pattern of the viral components and the intensity of the histological liver damage. During the follow up, there was an accumulation of both HBs and HBc Ag even in a period as short as 1 year. The 9 liver specimens examined after three years of transplantation showed a marked accumulation of both antigens. Thus the expression of HB Ag at the hepatocellular level seems to correlate better with the duration of antigenaemia than with the histological pattern.Lastly, on matched semithin and ultrathin sections, the ground glass appearance of cytoplasm appeared to correlate with smooth endoplasmic reticulum distorsion, irrespective of the simultaneous presence or absence of intravesicular tubular structures. The sanded nuclei expressed a rare massive accumulation of core antigen. 相似文献
44.
Ussama M. Abdel-Motal Louise Berg Anders Rosn Marita Bengtsson Cristopher J. Thorpe Jan Kihlberg Jan Dahmn Gran Magnusson Karl-Anders Karlsson Mikael Jondal 《European journal of immunology》1996,26(3):544-551
Cytotoxic T cells (CTL) recognize target proteins as short peptides presented by major histocompatibility complex (MHC) class I restriction elements. However, there is also evidence for peptide-independent T cell receptor (TCR) recognition of target proteins and non-protein structures. How such T cell responses are generated is presently unclear. We generated carbohydrate (CHO)-specific, MHC-unrestricted CTL responses by coupling di- and trisaccharides to Kb- or Db-binding peptides for direct immunization in mice. Four peptides and three CHO have been analyzed with the CHO either in terminal or central positions on the carrier peptide. With two of these glycopeptides, with galabiose (Galα1-4Gal; Gal2) bound to a homocysteine (via an ethylene spacer arm) in position 4 or 6 in a vesicular stomatitis virus nucleoprotein-derived peptide (RGYVYQGL binding to Kb), CTL were generated which preferentially killed target cells treated with glycopeptide compared to those treated with the core peptide. Polyclonal CTL were also found to kill target cells expressing the same Gal2 epitope in a glycolipid. By fractionation of CTL, preliminary data indicate that glycopeptide-specific Kb-restricted CTL and unrestricted CHO-specific CTL belong to different T cell populations with regard to TCR expression. The results demonstrate that hapten-specific unrestricted CTL responses can be generated with MHC class I-binding carrier peptides. Different models that might explain the generation of such responses are discussed. 相似文献
45.
The University of Missouri-Kansas City (UMKC) School of Medicine is a public medical school that opened in 1971 in response to a need to train more physicians in Missouri. As a six-year, integrated, combined-degree program leading to the baccalaureate and medical degrees, the school offers an innovative, nontraditional approach to medical education. In the past 35 years, UMKC has graduated over 2,400 physicians who are successful according to outcomes measures used at other medical schools. With recent interest in reforming medical education to prepare physicians for a changing world, a review of alternative models may be especially instructive.UMKC's academic plan offers a blueprint for the curriculum plan and governance of the school. The plan is built on four hallmarks: (1) a combined baccalaureate/MD program, (2) early exposure to clinical medicine, (3) small-group learning through the docent system, and (4) a continuing ambulatory care clinic experience for four years.This article catalogs the results of this plan including student, faculty, and graduates' perceptions of and satisfaction with the school's educational approach, students' achievement on licensing examinations and in the residency match, graduates' performance in residency programs, and their subsequent career patterns. The authors also discuss lessons learned and adjustments made in response to local needs in the context of a changing environment in education, health care, and health care delivery while continually improving the school's nontraditional approach to medical education. These include changes in basic and clinical science instruction, student assessment, faculty development, and funding and governance. 相似文献
46.
It is still an open question as to whether functional asymmetries in the human newborn derive from a single lateralized system or multiple subsystems based on different neural mechanisms. In the present study, asymmetries in head turning were compared to those in leg movements during stepping and placing, with the latter also being related to differences in leg mass. The effects of an active versus an inactive state or condition were examined for all three behaviors. No overall lateral biases were found for head turning or for the first foot to move in stepping and placing, and there were no concordances among them; however, there was an asymmetry in that the left foot had a shorter onset latency when compared to the right foot for both stepping and placing. Findings are discussed in terms of what they imply about underlying neural systems that have a bearing on expressions of newborn laterality, and also with regard to the impact of methodological differences in this area of study. 相似文献
47.
Effects of dexamethasone and transient malnutrition on rabbits infected with aerosolized Mycobacterium tuberculosis CDC1551 下载免费PDF全文
Kesavan AK Mendez SE Hatem CL Lopez-Molina J Aird K Pitt ML Dannenberg AM Manabe YC 《Infection and immunity》2005,73(10):7056-7060
Malnutrition is common in the developing world, where tuberculosis is often endemic. Rabbits infected with aerosolized Mycobacterium tuberculosis that subsequently became inadvertently and transiently malnourished had compromised cell-mediated immunity comparable to that of the rabbits immunosuppressed with dexamethasone. They had significant leukopenia and reduced delayed-type hypersensitivity responses. Malnutrition dampened cell-mediated immunity and would interfere with diagnostic tests that rely on intact CD4 T-cell responses. 相似文献
48.
49.
Masquelier B Bhaskaran K Pillay D Gifford R Balestre E Jørgensen LB Pedersen C van der Hoek L Prins M Balotta C Longo B Kücherer C Poggensee G Ortiz M de Mendoza C Gill J Fleury H Porter K;CASCADE Collaboration 《Journal of acquired immune deficiency syndromes (1999)》2005,40(5):505-511
OBJECTIVES: To examine factors influencing the rate of transmitted drug resistance (TDR) among seroconverters, with particular emphasis on 3 widely used genotypic drug resistance algorithms. METHODS: The study used data from CASCADE (Concerted Action on Seroconversion to AIDS and Death in Europe), a collaboration of seroconverter cohorts in Europe and Canada. Genotypic resistance data were derived within 18 months of the last seronegative test or date of laboratory evidence of acute infection and before the initiation of antiretroviral therapy. The Stanford algorithm was used to analyze each individual's nucleotide sequence. A multivariate logistic model was used to assess independent relationships between the presence of TDR and exposure category, sex, age at seroconversion, and year of seroconversion. The paper also describes 3 alternative definitions of resistance: the Stanford algorithm, the key resistance mutations defined by the International AIDS Society, and the Agence Nationale de Recherches sur le Sida (ANRS) algorithm. RESULTS: Forty-five of 438 patients (10.3%) seroconverting between 1987 and 2003 were infected with a drug-resistant HIV-1 variant. Forty patients (9.1%) showed resistance mutations to only 1 class of antiretroviral drugs, 2 (0.5%) to 2 classes, and 3 (0.7%) to 3 classes of antiretroviral therapy. It was suggested that individuals seroconverting later in calendar time were more likely to have TDR (relative risk 3.89 and 95% CI: 0.84 to 18.02, and relative risk 4.69 and 95% CI: 1.03 to 21.31, for 1996-1999 and 2000-2003, respectively, compared with pre-1996; P trend = 0.08). This trend was apparent regardless of the definition of TDR used. The total estimated proportion of individuals with TDR varied between 10.3% and 15.5% according to which definition was used. CONCLUSIONS: Evidence was found for the rise of TDR over time. A specific definition of what constitutes TDR rather than a simple list of mutations is needed. 相似文献
50.
Iréne?LundEmail author Thomas?Lundeberg Louise?Sandberg Cecilia?Norrbrink?Budh Jan?Kowalski Elisabeth?Svensson 《BMC medical research methodology》2005,5(1):31