全文获取类型
收费全文 | 22694篇 |
免费 | 1672篇 |
国内免费 | 62篇 |
专业分类
耳鼻咽喉 | 225篇 |
儿科学 | 889篇 |
妇产科学 | 771篇 |
基础医学 | 2912篇 |
口腔科学 | 235篇 |
临床医学 | 2925篇 |
内科学 | 3910篇 |
皮肤病学 | 514篇 |
神经病学 | 2249篇 |
特种医学 | 455篇 |
外科学 | 2308篇 |
综合类 | 239篇 |
一般理论 | 36篇 |
预防医学 | 3238篇 |
眼科学 | 297篇 |
药学 | 1477篇 |
中国医学 | 21篇 |
肿瘤学 | 1727篇 |
出版年
2024年 | 32篇 |
2023年 | 284篇 |
2022年 | 357篇 |
2021年 | 788篇 |
2020年 | 483篇 |
2019年 | 807篇 |
2018年 | 828篇 |
2017年 | 619篇 |
2016年 | 645篇 |
2015年 | 682篇 |
2014年 | 934篇 |
2013年 | 1346篇 |
2012年 | 2047篇 |
2011年 | 2177篇 |
2010年 | 1119篇 |
2009年 | 1000篇 |
2008年 | 1586篇 |
2007年 | 1683篇 |
2006年 | 1516篇 |
2005年 | 1324篇 |
2004年 | 1161篇 |
2003年 | 1033篇 |
2002年 | 918篇 |
2001年 | 114篇 |
2000年 | 61篇 |
1999年 | 88篇 |
1998年 | 154篇 |
1997年 | 86篇 |
1996年 | 70篇 |
1995年 | 74篇 |
1994年 | 54篇 |
1993年 | 38篇 |
1992年 | 28篇 |
1991年 | 25篇 |
1990年 | 21篇 |
1989年 | 17篇 |
1988年 | 24篇 |
1987年 | 22篇 |
1986年 | 27篇 |
1985年 | 16篇 |
1984年 | 16篇 |
1983年 | 14篇 |
1982年 | 17篇 |
1981年 | 11篇 |
1980年 | 9篇 |
1979年 | 10篇 |
1976年 | 5篇 |
1974年 | 8篇 |
1973年 | 7篇 |
1931年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
91.
Susceptible strains of mice that are naturally or experimentally infected with murine intestinal helicobacter species develop hepatic inflammatory lesions that have previously been described as chronic active hepatitis. The inflammatory infiltrates in some models of chronic autoimmunity or inflammation resemble tertiary lymphoid organs hypothesized to arise by a process termed lymphoid organ neogenesis. To determine whether hepatic inflammation caused by infection with helicobacter could give rise to tertiary lymphoid organs, we used fluorescence-activated cell sorting, immunohistochemistry, and in situ hybridization techniques to identify specific components characteristic of lymphoid organs in liver tissue sections and liver cell suspensions from helicobacter-infected mice. Small venules (high endothelial venules [HEVs]) in inflammatory lesions in Helicobacter species-infected livers were positive for peripheral node addressin. Mucosal addressin cell adhesion molecule also stained HEVs and cells with a staining pattern consistent with scattered stromal cells. The chemokines SLC (CCL 21) and BLC (CXCL13) were present, as were B220-positive B cells and T cells. The latter included a na?ve (CD45lo-CD62Lhi) population. These findings suggest that helicobacter-induced chronic active hepatitis arises through the process of lymphoid organ neogenesis. 相似文献
92.
The role of histone acetylation in SMN gene expression 总被引:7,自引:0,他引:7
Kernochan LE Russo ML Woodling NS Huynh TN Avila AM Fischbeck KH Sumner CJ 《Human molecular genetics》2005,14(9):1171-1182
93.
Prabhakar V Grinstaff MW Alarcon J Knors C Solan AK Niklason LE 《Journal of biomedical materials research. Part A》2003,67(1):303-311
Techniques have been developed to culture bovine or porcine vascular cells on polyglycolic acid (PGA) scaffolds to form engineered vessels. Previously, it was shown that smooth muscle cells (SMCs) that were in close proximity to PGA remnants after 8 weeks of culture had lower expression of SMC markers of differentiation and were more mitotic compared with SMCs that were distant from polymer residuals. Modifications of PGA were explored as a means to minimize residual polymer fragments after culture. To hasten degradation, polymer was treated with heat, NaOH, or gamma-irradiation. Differential scanning calorimetry, mass and tensile strength degradation, and inherent viscosity were used to assess polymer characteristics. When polymer was maintained in aqueous conditions, tensile strength of treated PGA degraded to zero within 3 weeks for each treatment. Engineered vessel constructs cultured on NaOH and gamma-treated polymer displayed smooth muscle alpha-actin throughout the vessel wall. Scaffold treatment impacted graft morphology, cellular differentiation, and mechanical integrity. 相似文献
94.
Bangsberg DR Bronstone A Chesney MA Hecht FM 《Journal of acquired immune deficiency syndromes (1999)》2002,31(Z3):S107-S111
Adherence to HIV antiretroviral therapy is closely associated with viral load suppression, progression to AIDS, and death in HIV-infected people. There is, however, no standardized approach to adherence assessment in routine clinical practice, and several studies suggest that providers rarely estimate adherence better than chance. Computer-assisted self-interview technology is an efficient means to identify HIV antiretroviral regimen errors and monitor adherence in order to maximize the benefits of therapy. 相似文献
95.
Wheat streak mosaic virus is a Tritimovirus, a member of the Potyviridae family, which includes the very large Potyvirus genus. We have examined wheat streak mosaic virus by electron microscopy and fiber diffraction from partially oriented sols, and analyzed the results to estimate the symmetry and structural parameters of the viral helix. The virions have an apparent radius of 63 +/- 5 A. The viral helix has a pitch of 33.4 A +/- 0.6 A. There appear to be 6.9 subunits per turn of the helix, although we cannot completely eliminate values of 5.9 or 7.9 for this parameter. 相似文献
96.
Pomés A Helm RM Bannon GA Burks AW Tsay A Chapman MD 《The Journal of allergy and clinical immunology》2003,111(3):640-645
BACKGROUND: Peanut allergy is an important health problem in the United States, affecting approximately 0.6% of children. Inadvertent exposure to peanut is a risk factor for life-threatening food-induced anaphylaxis. OBJECTIVE: The purpose of this investigation was to develop an immunoassay for a major peanut allergen, Ara h 1, to detect peanut allergen in foods so that the risk of inadvertent exposure can be reduced. METHODS: A specific 2-site monoclonal antibody-based ELISA was developed to measure Ara h 1 in foods. The sensitivity of the assay was 30 ng/mL. Ara h 1 was measured in foods (n = 83) with or without peanut and in experiments to optimize allergen yield and to determine peanut contamination in spiked foods. RESULTS: Ara h 1 levels in food products ranged from less than 0.1 microg/g to 500 microg/g. Ara h 1 measured in ng/mL was transformed to microg/g for food products. Peanut butter contained the highest amounts of Ara h 1. Peanut extracts contained from 0.5 to 15 mg Ara h 1/g of peanut depending on the extraction conditions. Optimal extraction of Ara h 1 was obtained by using phosphate buffer with 1 mol/L NaCl and Tween at 60 degrees C. Ara h 1 was not always detected in presence of chocolate under the extraction conditions tested. Spiking experiments showed that the assay could detect approximately 0.1% Ara h 1 contamination of food with ground peanut. There was an excellent correlation between Ara h 1 levels and peanut content measured by using a commercial polyclonal antibody-based ELISA (r = 93, n = 31, P <.001). CONCLUSION: A new sensitive and specific monoclonal antibody-based ELISA was used to monitor Ara h 1 content in food products. This assay should be useful for monitoring peanut contamination in the food manufacturing and processing industry and in developing thresholds for sensitization or allergic reaction in persons with peanut allergy. 相似文献
97.
98.
Morse MA Garst J Osada T Khan S Hobeika A Clay TM Valente N Shreeniwas R Sutton MA Delcayre A Hsu DH Le Pecq JB Lyerly HK 《Journal of translational medicine》2005,3(1):9-8
BACKGROUND: There is a continued need to develop more effective cancer immunotherapy strategies. Exosomes, cell-derived lipid vesicles that express high levels of a narrow spectrum of cell proteins represent a novel platform for delivering high levels of antigen in conjunction with costimulatory molecules. We performed this study to test the safety, feasibility and efficacy of autologous dendritic cell (DC)-derived exosomes (DEX) loaded with the MAGE tumor antigens in patients with non-small cell lung cancer (NSCLC). METHODS: This Phase I study enrolled HLA A2+ patients with pre-treated Stage IIIb (N = 4) and IV (N = 9) NSCLC with tumor expression of MAGE-A3 or A4. Patients underwent leukapheresis to generate DC from which DEX were produced and loaded with MAGE-A3, -A4, -A10, and MAGE-3DPO4 peptides. Patients received 4 doses of DEX at weekly intervals. RESULTS: Thirteen patients were enrolled and 9 completed therapy. Three formulations of DEX were evaluated; all were well tolerated with only grade 1-2 adverse events related to the use of DEX (injection site reactions (N = 8), flu like illness (N = 1), and peripheral arm pain (N = 1)). The time from the first dose of DEX until disease progression was 30 to 429+ days. Three patients had disease progression before the first DEX dose. Survival of patients after the first DEX dose was 52-665+ days. DTH reactivity against MAGE peptides was detected in 3/9 patients. Immune responses were detected in patients as follows: MAGE-specific T cell responses in 1/3, increased NK lytic activity in 2/4. CONCLUSION: Production of the DEX vaccine was feasible and DEX therapy was well tolerated in patients with advanced NSCLC. Some patients experienced long term stability of disease and activation of immune effectors. 相似文献
99.
Utian WH Janata JW Barbier S Rosen AS Mayer MH Taylor MB 《Menopause (New York, N.Y.)》2004,11(3):275-280
OBJECTIVE: The Utian Quality of Life Scale (UQOL) is a new questionnaire used to quantify patient perception of quality of life in postmenopausal women. The current study is the first to use the UQOL in ascertaining treatment effects on quality of life in postmenopausal women. DESIGN: This was a randomized, double-blind, placebo-controlled study of healthy postmenopausal women. Participants were randomized to raloxifene 60 mg/day or placebo. Participants completed the UQOL at baseline, at 3 months, and at the 6-month study endpoint. RESULTS: A total of 74 women (mean age, 55.6 years) were randomized. In the overall population, there were no significant changes from baseline to 6 months within or between treatment groups in any of the domains or total score, although raloxifene was associated with positive changes from baseline in the occupational (P = 0.093) and health (P = 0.055) domains. In women who completed the study, raloxifene was associated with a significant improvement from baseline in the occupational (P = 0.041) and health (P = 0.025) domains and in the total score (P = 0.044), whereas placebo had no effect. There were no statistically significant differences between raloxifene and placebo in any of the domains or total score. CONCLUSION: Although there were no treatment group differences, raloxifene was associated with an improvement from baseline in the occupational and health domains and in the overall score of the UQOL. Larger studies are needed using the UQOL as a primary endpoint to determine whether the positive effects of raloxifene on quality of life observed in this trial are real or a chance finding. 相似文献
100.
Amy H. Kim Paul M. Macev Ph.D. Mary A. Woo Pearl L. Yu Thomas G. Keens David Gozal Ronald M. Harper 《Somnologie - Schlafforschung und Schlafmedizin》2002,6(3):109-115
Summary Question of the Study Congenital central hypoventilation syndrome (CCHS) subjects exhibit diminished respiratory-related heart rate variation in addition to defining characteristics of CO2 insensitivity and reduced ventilatory drive during sleep. Loss of cardiovascular and breathing coupling may diminish blood pressure influences on breathing; such influences may be determined by evaluating cardiorespiratory responses to different pressor challenges.
Patients and Methods Ten children with CCHS and 10 age- and gender-matched controls were subjected to a forehead cold pressor challenge and to Valsalva maneuvers. Heart and respiratory rates and variability during 30-s baseline and 120-s challenge periods were assessed with scatterplot displays and by analysis of variance procedures.
Results Cold pressor challenges enhanced breathing efforts and increased respiratory-related heart rate variation in controls but not in CCHS patients, while lower frequency heart rate variability increased in both controls and CCHS subjects. Heart rate variation resulting from voluntary expiratory efforts was present but slightly reduced in CCHS. Respiratory and cardiac rate trends differed in control and CCHS cases.
Conclusions More-rapidly changing heart rate variation from spontaneous or reflexively-induced sources is diminished in CCHS but remains intact from voluntary expiratory efforts, as does slower variation. Loss of reflexive influences on breathing from blood pressure changes may attenuate a source of respiratory drive. 相似文献
Patients and Methods Ten children with CCHS and 10 age- and gender-matched controls were subjected to a forehead cold pressor challenge and to Valsalva maneuvers. Heart and respiratory rates and variability during 30-s baseline and 120-s challenge periods were assessed with scatterplot displays and by analysis of variance procedures.
Results Cold pressor challenges enhanced breathing efforts and increased respiratory-related heart rate variation in controls but not in CCHS patients, while lower frequency heart rate variability increased in both controls and CCHS subjects. Heart rate variation resulting from voluntary expiratory efforts was present but slightly reduced in CCHS. Respiratory and cardiac rate trends differed in control and CCHS cases.
Conclusions More-rapidly changing heart rate variation from spontaneous or reflexively-induced sources is diminished in CCHS but remains intact from voluntary expiratory efforts, as does slower variation. Loss of reflexive influences on breathing from blood pressure changes may attenuate a source of respiratory drive. 相似文献