全文获取类型
收费全文 | 56976篇 |
免费 | 3248篇 |
国内免费 | 241篇 |
专业分类
耳鼻咽喉 | 774篇 |
儿科学 | 1308篇 |
妇产科学 | 1142篇 |
基础医学 | 7192篇 |
口腔科学 | 2758篇 |
临床医学 | 4303篇 |
内科学 | 14635篇 |
皮肤病学 | 1326篇 |
神经病学 | 4732篇 |
特种医学 | 1236篇 |
外科学 | 8770篇 |
综合类 | 359篇 |
一般理论 | 20篇 |
预防医学 | 3976篇 |
眼科学 | 1278篇 |
药学 | 3110篇 |
1篇 | |
中国医学 | 176篇 |
肿瘤学 | 3369篇 |
出版年
2023年 | 400篇 |
2022年 | 890篇 |
2021年 | 2030篇 |
2020年 | 1073篇 |
2019年 | 1644篇 |
2018年 | 1955篇 |
2017年 | 1228篇 |
2016年 | 1373篇 |
2015年 | 1621篇 |
2014年 | 2339篇 |
2013年 | 2837篇 |
2012年 | 4739篇 |
2011年 | 4894篇 |
2010年 | 2719篇 |
2009年 | 2346篇 |
2008年 | 3913篇 |
2007年 | 3989篇 |
2006年 | 3779篇 |
2005年 | 3598篇 |
2004年 | 3077篇 |
2003年 | 2719篇 |
2002年 | 2462篇 |
2001年 | 294篇 |
2000年 | 222篇 |
1999年 | 359篇 |
1998年 | 457篇 |
1997年 | 349篇 |
1996年 | 304篇 |
1995年 | 307篇 |
1994年 | 255篇 |
1993年 | 217篇 |
1992年 | 183篇 |
1991年 | 143篇 |
1990年 | 100篇 |
1989年 | 88篇 |
1988年 | 94篇 |
1987年 | 82篇 |
1986年 | 88篇 |
1985年 | 87篇 |
1984年 | 108篇 |
1983年 | 97篇 |
1982年 | 100篇 |
1981年 | 107篇 |
1980年 | 98篇 |
1979年 | 63篇 |
1978年 | 63篇 |
1977年 | 76篇 |
1976年 | 53篇 |
1975年 | 40篇 |
1974年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Jose S. Pulido Ikuko Sugaya Jordan Comstock Kiminobu Sugaya 《Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie》2007,245(6):889-893
Purpose Reelin is important in the guidance of neuronal stem cells in the central nervous system during normal development. We wished
to determine whether reelin is expressed in the retina and cornea after injury.
Methods Mice underwent laceration of their retina as well as corneal epithelial debridement. The mice were sacrificed at 3 days, and
eyes were fixed and stained for reelin expression and reelin messenger ribonucleic acid (mRNA).
Results In normal eyes, reelin was expressed only at very low levels in the ganglion cell layer of the retina and the endothelial
cell layer of the cornea. In injured eyes, there was marked expression in reelin immunoreactivity in the retina and cornea.
Reelin gene expression was seen in the retina and cornea.
Conclusions Reelin is expressed during normal retinogenesis. This study shows that reelin is also upregulated following injury to the
retina and cornea. The expression of reelin following injury suggests that reelin may play an important role in regulating
stem cell trafficking in neuronal and nonneuronal tissues following injury similar to its role in normal organogenesis.
For consideration of publication in Graefe’s Archive for Clinical and Experimental Ophthalmology. 相似文献
82.
83.
Jose Sanchez-Chapula Alejandro Elizalde 《Naunyn-Schmiedeberg's archives of pharmacology》1987,336(2):218-223
Summary The effects of histamine on the transmembrane electrical activity of cells of small preparations (0.5 × 0.5 mm) of guinea-pig and rabbit sinoatrial- and atrioventricular-nodes were studied. Histamine at concentrations above 10–7 mol/l increased the firing rate, the rate of diastolic depolarization, the maximum diastolic potential, the amplitude and the maximum rate of depolarization of the action potential of pacemaker cells of rabbit and guineapig sinoatrial cells and rabbit atrioventricular cells. These effects were antagonized by the HZ-receptor blocker cimetidine (2.5 × 10–6 mol/1) but they were not modified by the H1-receptor blocker chlorphenamine (2.5 and 5×10–6 mol/1). Small preparations of guinea-pig atrioventricular node did not exhibit spontaneous activity, but it was induced by histamine and blocked by cimetidine. Histamine increased the maximum upstroke velocity of propagated action potential of cells of the central part of complete atrioventricular node in both species studied. These effects were blocked by cimetidine, but not by chlorphenamine. It is concluded that the increase in automaticity induced by histamine in guinea-pig and rabbit sinoatrial and atrioventricular nodes was due to stimulation of H2receptors. Histamine did not depress electrical activity of atrioventricular node cells, but rather increased it. This effect was due to H2-receptor stimulation.
Send offprint requests to: J. Sanchez-Chapula at the above address 相似文献
84.
85.
86.
87.
88.
Landa Nerea MD Aller Oscar MD Landa-Gundin Nagore RN Torrontegui Jaione RN Azpiazu Jose L. MD 《Dermatologic surgery》2005,31(6):726-728
BACKGROUND: Pilonidal disease is a chronic disease of the natal cleft. Recurrent follicular infection is the causative factor. Surgical treatment has a significant failure rate, and recurrence is common. Laser removal of hair in the natal cleft could be an alternative to surgery. OBJECTIVE: To determine the effectiveness of laser hair removal in the natal cleft on pilonidal disease. METHODS: Six young men with recurrent pilonidal disease were treated with laser epilation in our clinic from 2000 to 2003. Most patients had a history of one or more surgical treatments in the area, and all patients had suffered recurrent folliculitis for years. An alexandrite laser was mostly used, although, occasionally, an intense pulsed light device was used. The number of epilation treatments ranged from 3 to 11, performed at 6- to 8-week intervals. RESULTS: All patients experienced progressive resolution of the folliculitis with the laser epilation treatments. No more surgical treatments have been needed. The treatments were simple and quick, and there were no complications. CONCLUSION: Laser epilation of the natal cleft should be considered a first choice treatment for recurrent pilonidal disease. Preventive laser epilation of the natal cleft in patients with recurrent folliculitis could avoid future surgery. 相似文献
89.
James Edward Paul Elizabeth Ling Carlos Lalonde Lehana Thabane 《Journal canadien d'anesthésie》2007,54(10):799-810
PURPOSE: To determine if deliberate hypotension decreases blood loss and transfusion requirements in patients undergoing orthopedic surgery, a systematic review of all randomized trials addressing this issue was undertaken. METHODS: Electronic databases, citations lists and review articles were searched for potential articles. Relevant articles met the following inclusion criteria: English language, humans undergoing orthopedic surgery, deliberate hypotension used by any method, intraoperative blood loss measured as an outcome, and the trial methodology being randomized and controlled. Four outcomes were analyzed, including estimated blood loss, blood transfused, surgery duration, and quality of the surgical field. For all analyses, the random-effects model was used. RESULTS: Seventeen articles met the inclusion criteria. The surgeries studied included total hip arthroplasty (seven), orthognathic surgery (eight), total knee arthroplasty (one) and spinal fusion (one). A total of 636 patients were randomized across all studies. For blood loss, the overall weighted mean difference favoured treatment, with a savings of about 287 mL of blood [95% confidence interval (CI): -447, -127]. The mean differences also showed a statistically significant benefit for deliberate hypotension in reducing transfusion requirements (-667 mL of blood transfused; 95% CI: -963, -370). Deliberate hypotension was not shown to reduce the duration of surgery (-1.9 min of surgery; 95% CI: -7.2, 3.5) or improve surgical conditions (surgical field quality rating -0.5; 95% CI: -1.1, 0.2). CONCLUSION: This review provides some support for the use of deliberate hypotension in reducing blood loss and transfusion requirements in orthopedic surgery, but these results are tempered by the small sample sizes and poor methodological quality of published studies. 相似文献
90.
The antero-posterior diameter of the lumbar dural sac does not predict sensory levels of spinal anesthesia for Cesarean delivery 总被引:1,自引:0,他引:1
Cristian Arzola Mrinalini Balki Jose C. A. Carvalho 《Journal canadien d'anesthésie》2007,54(8):620-625
PURPOSE: The lumbosacral cerebrospinal fluid (CSF) volume, as assessed by magnetic resonance imaging, is a major determinant of the intrathecal spread of local anesthetics. Ultrasound imaging of the lumbar spine allows measurement of dural sac dimensions, which we hypothesize can be used to estimate CSF volume. The purpose of this study was to investigate whether the dural sac antero-posterior diameter correlates with sensory levels of spinal anesthesia during elective Cesarean delivery (CD). METHODS: After Research Ethics Board approval and informed consent, a prospective observational study enrolled 41 patients scheduled for elective CD under spinal anesthesia. With ultrasound imaging (transverse approach, 2-5 MHz curved array probe), we measured the antero-posterior diameter of the lumbar dural sac (dural sac diameter, DSD). Spinal anesthesia was administered with 0.75% hyperbaric bupivacaine 1.6 mL, fentanyl 10 microg and morphine 100 microg, with the patient in the sitting position. Sensory block levels were assessed with ice and pinprick every five minutes until peak sensory levels (PSL) were attained. Spearman's rank correlation was used to correlate DSD with PSL and time to attain PSL. RESULTS: There were no significant correlations between DSD and PSL assessed with ice (P = 0.474) or pinprick (P = 0.583). Similarly, there was no significant correlation between DSD and time to reach PSL, and between DSD and patient demographics. CONCLUSION: The lumbar DSD, as determined by ultrasound, is not a predictor of spinal anesthesia spread. Further research is necessary to understand if ultrasound findings can be used to predict intrathecal spread of local anesthetics. 相似文献