全文获取类型
收费全文 | 8257篇 |
免费 | 678篇 |
国内免费 | 36篇 |
专业分类
耳鼻咽喉 | 112篇 |
儿科学 | 308篇 |
妇产科学 | 319篇 |
基础医学 | 1058篇 |
口腔科学 | 260篇 |
临床医学 | 850篇 |
内科学 | 1484篇 |
皮肤病学 | 259篇 |
神经病学 | 722篇 |
特种医学 | 332篇 |
外科学 | 1100篇 |
综合类 | 219篇 |
一般理论 | 7篇 |
预防医学 | 760篇 |
眼科学 | 68篇 |
药学 | 554篇 |
中国医学 | 13篇 |
肿瘤学 | 546篇 |
出版年
2021年 | 113篇 |
2020年 | 63篇 |
2019年 | 102篇 |
2018年 | 116篇 |
2017年 | 88篇 |
2016年 | 91篇 |
2015年 | 134篇 |
2014年 | 178篇 |
2013年 | 283篇 |
2012年 | 345篇 |
2011年 | 355篇 |
2010年 | 205篇 |
2009年 | 183篇 |
2008年 | 319篇 |
2007年 | 365篇 |
2006年 | 321篇 |
2005年 | 339篇 |
2004年 | 324篇 |
2003年 | 336篇 |
2002年 | 301篇 |
2001年 | 283篇 |
2000年 | 302篇 |
1999年 | 244篇 |
1998年 | 92篇 |
1997年 | 72篇 |
1996年 | 81篇 |
1995年 | 77篇 |
1994年 | 75篇 |
1993年 | 58篇 |
1992年 | 187篇 |
1991年 | 209篇 |
1990年 | 199篇 |
1989年 | 175篇 |
1988年 | 178篇 |
1987年 | 196篇 |
1986年 | 189篇 |
1985年 | 165篇 |
1984年 | 146篇 |
1983年 | 113篇 |
1982年 | 77篇 |
1981年 | 79篇 |
1980年 | 68篇 |
1979年 | 106篇 |
1978年 | 78篇 |
1977年 | 59篇 |
1976年 | 64篇 |
1974年 | 78篇 |
1973年 | 91篇 |
1972年 | 74篇 |
1970年 | 78篇 |
排序方式: 共有8971条查询结果,搜索用时 15 毫秒
51.
Conway F. Saylor PhD Cynthia Cupit Swenson Ph.D. Paige Powell Ph.D. 《Child psychiatry and human development》1992,22(3):139-149
This article reports highlights from over 200 parents' observations of their preschoolers' play and verbalizations in the year following Hurricane Hugo. Commonly reported activities included reenactment and discussion of the event in multiple mediums, personification of Hugo, and expression of fears related to storms. Precocious concern for others, insight, and vocabulary were also noted. In these intact, relatively high functioning families, parents seemed able to facilitate their youngsters' adjustment without outside intervention.Portions of this report were presented in earlier form at the 1991 Society for Research in Child Development meeting in Seattle, Washington. 相似文献
52.
53.
54.
55.
R Whitley A Arvin C Prober S Burchett L Corey D Powell S Plotkin S Starr C Alford J Connor 《The New England journal of medicine》1991,324(7):444-449
BACKGROUND. Despite the use of vidarabine, herpes simplex virus (HSV) infection in neonates continues to be a disease of high morbidity and mortality. We undertook a controlled trial comparing vidarabine with acyclovir for the treatment of neonatal HSV infection. METHODS. Babies less than one month of age with virologically confirmed HSV infection were randomly and blindly assigned to receive either intravenous vidarabine (30 mg per kilogram of body weight per day; n = 95) or acyclovir (30 mg per kilogram per day; n = 107) for 10 days. Actuarial rates of mortality and morbidity among the survivors after one year were compared overall and according to the extent of the disease at entry into the study (infection confined to the skin, eyes, or mouth; encephalitis; or disseminated disease). RESULTS. After adjustment for differences between groups in the extent of disease, there was no difference between vidarabine and acyclovir in either morbidity (P = 0.83) or mortality (P = 0.27). None of the 85 babies with disease confined to the skin, eyes, or mouth died. Of the 31 babies in this group who were treated with vidarabine and followed for a year, 88 percent (22 of 25) were judged to be developing normally after one year, as compared with 98 percent (45 of 46) of the 54 treated with acyclovir (95 percent confidence interval for the difference, -4 to 24). For the 71 babies with encephalitis, mortality was 14 percent with vidarabine (5 of 36) and with acyclovir (5 of 35); of the survivors, 43 percent (13 of 30) and 29 percent (8 of 28), respectively, were developing normally after one year (95 percent confidence interval for the difference, -11 to 39). For the 46 babies with disseminated disease, mortality was 50 percent (14 of 28) with vidarabine and 61 percent (11 of 18) with acyclovir (95 percent confidence interval for the difference, -20 to 40); of the survivors, 58 percent (7 of 12) and 60 percent (3 of 5), respectively, were judged to be developing normally after one year (95 percent confidence interval for the difference, -40 to 50). Both medications were without serious toxic effects. CONCLUSIONS. In this multicenter, randomized, blinded study there were no differences in outcome between vidarabine and acyclovir in the treatment of neonatal HSV infection. The study lacked statistical power to determine whether there were sizable differences within the subgroups of those with localized HSV, encephalitis, or disseminated disease. 相似文献
56.
A M Bolinger K Y Young J G Gambertoglio C J Newth G Zureikat M Powell P Leung M B Affrime S Symchowicz J E Patrick 《The Journal of allergy and clinical immunology》1989,83(1):123-126
A study was conducted in 12 healthy, nonsmoking male volunteers to examine the effect of food intake on the absorption profile of albuterol repeat-action tablets. This randomized crossover study consisted of two phases separated by a 1-week washout period. All subjects fasted 10 hours preceding drug administration. Each subject received two 4 mg albuterol repeat-action tablets with and without a high fat content breakfast. Plasma albuterol concentrations were determined by a gas chromatographic/mass spectrophotometric assay. Relative bioavailability was assessed by comparing areas under the plasma-albuterol concentration time curves as well as peak concentrations and time to peak concentration. No significant differences were noted between the two treatment phases in the area under the curve or peak plasma concentrations. The areas under the curve were 100 and 105 hr.ng/ml when the drug was administered with and without food, respectively. The corresponding peak plasma concentration values were 9.4 and 10.4 ng/ml, respectively. The only significant difference observed was in the maximum time to reach peak plasma concentrations, which was delayed by about 1 hour when the drug was administered with food. Therefore, food has minimal effect on the absorption of albuterol from repeat-action tablets. 相似文献
57.
Wang H Lee JK Moursi AM Anderson D Winnard P Powell H Lannutti J 《Journal of biomedical materials research. Part A》2004,68(1):61-70
Microstructural factors may play a role in the osseointegration of calcium phosphates. In this paper, direct microstructural interactions between crystalline calcium phosphates and the biological milieu are reported. Degradation via exposure to osteoblast culture closely resembles in vivo interactions with subcutaneous tissues in a bovine model at early time periods. That these interactions were common to both experiments constitutes one of the few known examples of in vitro-in vivo correspondence. Interestingly, the degradation of phase pure hydroxyapatite (HA) in vitro was more rapid than that of biphasic HA in vivo. In both cases, grain extraction/pullout was frequently observed. This suggests a connection to smaller-scale observations of epitaxial CHA nucleation and growth on pre-existing HA grains. A microstructure in which the grain boundary is dissolving/corroding can apparently be disassembled by forces transmitted through biological structures. These observations are distinct from those of simple non-biological solutions and prove that biological environments can interact with the material beneath the ceramic-cell/ceramic-tissue interface. Many often ignored microstructural factors-grain size, shape, grain boundary strength and the presence of impurity phases-may in fact control degradation. We also suggest that even relatively modest initial grain sizes will, in combination with the mild/absent foreign body response to calcium phosphates, result in lengthy in vivo particle resistence. 相似文献
58.
The effect of experimental iron-overload on splenic T cell function: analysis using cloning techniques. 下载免费PDF全文
M F Good D E Chapman L W Powell J W Halliday 《Clinical and experimental immunology》1987,68(2):375-383
The effect of iron-overload on cell-mediated immunity was examined in C57 mice. Two methods of iron-loading were used: (i) dietary carbonyl iron which produced iron-loading primarily of parenchymal cells or (ii) intraperitoneal administration of iron-dextran which produced iron-loading predominantly of Kupffer cells. Both methods of iron-loading resulted in a diminished capacity of spleen cells to generate an allo-specific cytotoxic response in the absence of exogenous interleukin 2 (IL-2). Exogenous IL-2, however, restored the ability of spleen cells from iron-loaded mice to generate allo-specific cytotoxicity in bulk culture. Clonal assays for the precursor cells of cytotoxic T lymphocytes (CTL-P), performed in the presence of added IL-2, demonstrated that iron-loaded mice contained normal numbers of CTL-P. However, cultures of spleen cells from carbonyl iron-loaded mice generated less IL-2 following Concanavalin A stimulation, apparently as a result of a reduction in the number of IL-2-secreting cells amongst the spleen cell population. This work presents further evidence that iron-overload is associated with defective immunoregulatory control. 相似文献
59.
Plasma C3 degradation products (C3d) were measured in 65 normal pregnancies and compared with those of non-pregnant women. No significant difference was detected between the two groups, although a difference had been previously reported. Plasma C3d estimations give an indication of complement activation and may be used as an indicator of disease activity in patients with systemic lupus erythematosus (SLE), irrespective of pregnancy. 相似文献
60.
Modulation of Whole-Cell Currents in Plasmodium Falciparum-Infected Human Red Blood Cells by Holding Potential and Serum 总被引:3,自引:0,他引:3
Henry M. Staines Trevor Powell J. Clive Ellory Stéphane Egée Franck Lapaix Gaëtan Decherf Serge L. Y. Thomas Christophe Duranton† Florian Lang† Stephan M. Huber† 《The Journal of physiology》2003,552(1):177-183
Recent electrophysiological studies have identified novel ion channel activity in the host plasma membrane of Plasmodium falciparum -infected human red blood cells (RBCs). However, conflicting data have been published with regard to the characteristics of induced channel activity measured in the whole-cell configuration of the patch-clamp technique. In an effort to establish the reasons for these discrepancies, we demonstrate here two factors that have been found to modulate whole-cell recordings in malaria-infected RBCs. Firstly, negative holding potentials reduced inward currents (i.e. at negative potentials), although this result was highly complex. Secondly, the addition of human serum increased outward currents (i.e. at positive potentials) by approximately 4-fold and inward currents by approximately 2-fold. These two effects may help to resolve the conflicting data in the literature, although further investigation is required to understand the underlying mechanisms and their physiological relevance in detail. 相似文献