全文获取类型
收费全文 | 1418篇 |
免费 | 80篇 |
国内免费 | 12篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 95篇 |
妇产科学 | 12篇 |
基础医学 | 127篇 |
口腔科学 | 53篇 |
临床医学 | 182篇 |
内科学 | 273篇 |
皮肤病学 | 21篇 |
神经病学 | 40篇 |
特种医学 | 316篇 |
外科学 | 173篇 |
综合类 | 12篇 |
预防医学 | 67篇 |
眼科学 | 7篇 |
药学 | 60篇 |
肿瘤学 | 68篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 12篇 |
2020年 | 6篇 |
2019年 | 18篇 |
2018年 | 27篇 |
2017年 | 10篇 |
2016年 | 18篇 |
2015年 | 24篇 |
2014年 | 31篇 |
2013年 | 54篇 |
2012年 | 39篇 |
2011年 | 31篇 |
2010年 | 42篇 |
2009年 | 35篇 |
2008年 | 32篇 |
2007年 | 54篇 |
2006年 | 43篇 |
2005年 | 48篇 |
2004年 | 36篇 |
2003年 | 29篇 |
2002年 | 20篇 |
2001年 | 19篇 |
2000年 | 16篇 |
1999年 | 27篇 |
1998年 | 97篇 |
1997年 | 72篇 |
1996年 | 77篇 |
1995年 | 53篇 |
1994年 | 57篇 |
1993年 | 63篇 |
1992年 | 13篇 |
1991年 | 8篇 |
1990年 | 16篇 |
1989年 | 42篇 |
1988年 | 35篇 |
1987年 | 39篇 |
1986年 | 23篇 |
1985年 | 30篇 |
1984年 | 33篇 |
1983年 | 18篇 |
1982年 | 22篇 |
1981年 | 23篇 |
1980年 | 28篇 |
1979年 | 7篇 |
1978年 | 16篇 |
1977年 | 18篇 |
1976年 | 21篇 |
1975年 | 13篇 |
1930年 | 1篇 |
排序方式: 共有1510条查询结果,搜索用时 15 毫秒
101.
Schepers VP Visser-Meily AM Ketelaar M Lindeman E 《Archives of physical medicine and rehabilitation》2005,86(7):1472-1476
OBJECTIVE: To develop an easy-to-use prediction rule for social activity 1 year poststroke that can identify patients at risk for social inactivity. DESIGN: Inception cohort. SETTING: Rehabilitation center. PARTICIPANTS: Patients with a first-ever supratentorial stroke were selected in 4 Dutch rehabilitation centers. Data of 250 patients were available for analysis. Potential prognostic factors measured at admission were sex, age, marital status, prestroke employment status, educational level, type of stroke, hemisphere, motor impairment, trunk control, communication, and activities of daily living (ADL) dependency. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: Social activity measured by the Frenchay Activities Index (FAI) at 1 year poststroke. RESULTS: Multivariate backward linear regression analysis identified sex, age, marital status, motor impairment, communication, and ADL dependency as important predictors of the FAI score 1 year poststroke. An easy-to-use score chart was constructed that could identify patients at risk for social inactivity. The score chart proved to be well able to discriminate poor social functioning from moderate to good social functioning (area under the curve = .85). CONCLUSIONS: Identifying patients at risk enables health care professionals to focus on the social activity of this patient subgroup at an early stage in the care process. 相似文献
102.
Kim I Barnes AJ Oyler JM Schepers R Joseph RE Cone EJ Lafko D Moolchan ET Huestis MA 《Clinical chemistry》2002,48(9):1486-1496
BACKGROUND: The ease, noninvasiveness, and safety of oral fluid collection have increased the use of this alternative matrix for drugs-of-abuse testing; however, few controlled drug administration data are available to aid in the interpretation of oral fluid results. METHODS: Single oral codeine doses (60 and 120 mg/70 kg) were administered to 19 volunteers. Oral fluid and plasma were analyzed for free codeine, norcodeine, morphine, and normorphine by solid-phase extraction combined with gas chromatography-mass spectrometry (SPE/GC-MS). Physiologic and subjective effects were examined. RESULTS: Mean (SE) peak codeine concentrations were 214.2 +/- 27.6 and 474.3 +/- 77.0 micro g/L in plasma and 638.4 +/- 64.4 and 1599.3 +/- 241.0 micro g/L in oral fluid. The oral fluid-to-plasma ratio for codeine was relatively constant ( approximately 4) from 1 to 12 h. The mean half-life (t(1/2)) of codeine was 2.2 +/- 0.10 h in plasma and 2.2 +/- 0.16 h in oral fluid. Significant dose-related miosis and increases in sedation, psychotomimetic effect, and "high" occurred after the high dose. Mean codeine oral fluid detection time was 21 h with a 2.5 microg/L cutoff, longer than that of plasma (12-16 h). Detection times with the proposed Substance Abuse and Mental Health Services Administration cutoff (40 microg/L) were only 7 h. Norcodeine, but not morphine or normorphine, was quantified in both plasma and oral fluid. CONCLUSIONS: The disposition of codeine over time was similar in plasma and oral fluid, but because of high variability, oral fluid codeine concentrations did not reliably predict concurrent plasma concentrations. Oral fluid testing is a useful alternative matrix for monitoring codeine exposure with a detection window of 7-21 h for single doses, depending on cutoff concentrations. These controlled drug administration data should aid in the interpretation of oral fluid codeine results. 相似文献
103.
Two patients are described in whom clinically significant red blood cell alloantibodies could be demonstrated only by in vivo 51chromium (51Cr) survival studies. The first patient had experienced a severe delayed hemolytic transfusion reaction to four units of crossmatch compatible blood. Serial phenotype studies suggested the presence of a serologically undetectable anti-c (hr') antibody. 51Cr survival of c- positive red blood cells was one per cent at 24 hours, while survival of c-negative red blood cells was 80 per cent at 24 hours. The second patient had multiple red blood cell alloantibodies. An anti-c antibody was suspected but could not be convincingly demonstrated by in vitro techniques. 51Cr survival of c-positive red blood cells, however, was 57 per cent at 24 hours and 17 per cent at 48 hours. 51Chromium red blood cell survival studies should be considered whenever an unexplained hemolytic transfusion reaction occurs, or when an expected red blood cell alloantibody cannot be demonstrated by in vitro laboratory studies. 相似文献
104.
Transfusion-associated graft-versus-host disease (TA-GVHD) may occur whenever immunologically competent allogeneic lymphocytes are transfused to an immunocompromised recipient. Irradiation of blood components eliminates the risk of TA-GVHD but may damage the cellular elements in the transfused component, particularly if the cells are stored for prolonged periods in the irradiated state. To study the effect of irradiation on long-term storage of red cells, AS-1 red cells from eight normal subjects were prepared on two occasions. On one occasion, the units were stored as standard AS-1 red cells for 42 days at 4 degrees C; on the other, they were exposed to 3000 cGy radiation within 4 hours of collection and then were stored as AS-1 red cells for 42 days at 4 degrees C. The donations were at least 12 weeks apart. Irradiated units demonstrated significant elevations in poststorage plasma hemoglobin (Hb) (623 +/- 206 vs. 429 +/- 194 g/dL [6230 +/- 2060 vs. 4290 +/- 1940 g/L], p less than 0.02) and plasma potassium (78 +/- 4 vs. 43 +/- 9 mEq/L [78 +/- 4 vs. 43 +/- 9 mmol/L], p less than 0.01) and significant decreases in red cell ATP (1.9 +/- 0.2 vs. 2.1 +/- 0.3 microM/g Hb, p less than 0.04) and 24-hour posttransfusion red cell recovery (68.5 vs. 78.4%, p less than 0.02), as compared to nonirradiated units. It can be concluded that irradiation with 3000 cGy damages red cells and that long-term storage in the irradiated state may enhance this damage. Red cells should not be stored for 42 days after irradiation with 3000 cGy. 相似文献
105.
Pathophysiology and pharmacology of migraine. Is there a place for antiemetics in future treatment strategies? 总被引:1,自引:0,他引:1
This article reviews the pathophysiology and pharmacology of emesis in relation to migraine pathogenesis. Also, the place of antiemetic and gastrointestinal prokinetic agents in current and future acute migraine treatment strategies is reviewed. The mechanisms of action of current and novel acute migraine therapies are considered with respect to the neurogenic and vascular hypotheses. Control of migraine-associated nausea and vomiting is often achieved with the benzamide dopamine D2 receptor antagonist metoclopramide. This drug also has 5HT3 receptor antagonist activity and reproducibly stimulates gastric motility to increase the availability of orally administered drugs. Other antiemetic and gastroprokinetic agents with potential value for the treatment of migraine-associated nausea and vomiting could speed absorption of oral antimigraine therapies without central nervous system side effects. Domperidone, a dopamine D2 receptor antagonist that does not cross the blood brain barrier is relatively free of the central side-effect liability of metoclopramide. Cisapride, a benzamide 5HT4 receptor agonist gastrointestinal prokinetic drug, lacks dopamine antagonist activity. A controlled comparison of these agents as migraine co-therapies could provide information on the importance of peripheral and central mechanisms in migraine-associated nausea and vomiting and improve antimigraine treatment options. 相似文献
106.
自美国国家骨髓库(NMDP)开展第一例无关供者移植以来,至今已有20年.NMDP目前的库容量已逾700万,已为6大洲提供了30 000多份无关供者造血干细胞.这一辉煌成就是美国国家骨髓库600多名工作人员共同努力的结果,同时也得益于广泛的国际合作,包括171个移植中心,73个供者中心,24个脐血库,97个骨髓采集中心,91个血液净化中心,26个HLA分型实验室和26个合作供者登记处.本文回顾了美国国家骨髓库的历史,阐述了20年来移植病人、移植物来源和预处理方案几方面的主要变化趋势. 相似文献
107.
BACKGROUND: Chagas' disease, caused by the protozoan parasite Trypanosoma cruzi, is endemic to Latin America and may be transmitted in the United States via blood donated by infected immigrants. Blood- borne pathogens such as T. cruzi require supplemental testing for confirmation of seroreactivity. STUDY DESIGN AND METHODS: A study was undertaken to determine an optimal scheme for confirmation of seroreactivity in repeatedly reactive samples identified by the Chagas antibody enzyme immunoassay (EIA). The procedure for initial confirmation involves three purified antigens coated onto three separate polystyrene beads and uses an EIA format. If the sample is reactive with two of three or three of three antigens, it is confirmed as seroreactive. If none or one of three beads is reactive, the sample is indeterminate and subjected to a radioimmunoprecipitation assay (RIPA). The RIPA must demonstrate characteristic bands at 32, 34, and 90 kDa. RESULTS: When tested with sera from persons with potentially cross-reactive diseases (n = 39) or against a presumed negative population from southeast Wisconsin (n = 289), the confirmatory EIA had a specificity of 100 percent. Sensitivity was 100 percent (28/28) with xenodiagnosis-positive sera and 97.6 percent (80/82) with chagasic sera from Latin America. The RIPA showed a specificity of 100 percent in EIA- nonreactive samples (n = 100) and a sensitivity of 100 percent with both xenodiagnosis-positive (28/28) and chagasic (82/82) sera. CONCLUSION: The confirmatory EIA and the RIPA together provide a highly specific and sensitive means of confirming seroreactivity for antibodies to T. cruzi. 相似文献
108.
109.
Schepers E Glorieux G Dou L Cerini C Gayrard N Louvet L Maugard C Preus P Rodriguez-Ortiz M Argiles A Brunet P Cohen G Jankowski J Jankowski V Massy Z Rodriguez M Vanholder R;European Uremic Toxin Work Group 《Blood purification》2010,30(4):277-287
Chronic kidney disease is considered a major cause of cardiovascular risk and non-traditional risk factors remain largely unknown. The in vitro toxicity of 10 guanidino compounds (GCs) was evaluated via a standardized approach on different cell systems of relevance in cardiovascular disease. The parameters evaluated were production of reactive oxygen species, expression of surface molecules, cell proliferation, cytotoxicity and calcification. Several GCs had a stimulatory effect on monocytes and granulocytes (SDMA, creatine and guanidinobutyric acid (GBA)). Some GCs (guandine (G), guanidinosuccinic acid (GSA) and SDMA) inhibited endothelial cell proliferation or reduced calcification in osteoblast-like human VSMC (ADMA, GSA and SDMA). Stimulation of osteoclastogenesis could be demonstrated for ADMA, G, guanidinoacetic acid and GBA in a RAW264.7 cell line. No compounds were cytotoxic to AoSMC or endothelial cells, nor influenced their viability. GCs, especially SDMA, likely contribute to cardiovascular complications in uremia, mainly those related to microinflammation and leukocyte activation. 相似文献
110.
Acute microinjection of mu-, delta-, or kappa-opioid receptor (MOPr, DOPr, KOPr) agonists into the rostral ventromedial medulla (RVM) produces antinociception. Thermal antinociception produced by MOPr and DOPr agonists is potentiated during inflammation [Hurley RW, Hammond DL. The analgesic effects of supraspinal mu and delta opioid receptor agonists are potentiated during persistent inflammation. J Neurosci 2000;20:1249-59]. Whether this potentiation extends to other stimulus modalities or to KOPr agonists is unknown. To examine these issues, rats received a unilateral intraplantar injection of complete Freund's adjuvant (CFA). Antinociception produced by RVM infusion of the KOPr agonist, U69593, and the MOPr agonist, DAMGO, was tested 4h-2 weeks thereafter. Thermal paw withdrawal latencies (PWLs) were assessed using the Hargreaves method. Mechanical thresholds were determined with the Von Frey and Randall-Selitto method. PWLs of the inflamed paw were reduced 4h-2 weeks after CFA injection. Infusion of either U69593 or DAMGO increased PWLs in CFA treated rats. A bilateral enhancement of the response to both agonists was observed 2 weeks relative to 4h post-CFA injection. Mechanical thresholds of the inflamed paw were decreased for >2 weeks post-CFA injection. Infusion of either agonist elevated thresholds of the inflamed and non-inflamed paws of CFA-treated rats. The magnitude of these effects was greater 2 weeks post-CFA injection for DAMGO and increased progressively for U69593. These data demonstrate that RVM infusion of MOPr or KOPr agonists attenuates CFA-evoked thermal and tactile allodynia and that these effects increase during prolonged inflammation. The augmented response of the non-inflamed paw to agonists suggests that inflammation induces centrally-mediated neuroplastic changes which enhance MOPr- and KOPr-mediated antinociception. 相似文献