全文获取类型
收费全文 | 55257篇 |
免费 | 4600篇 |
国内免费 | 1667篇 |
专业分类
耳鼻咽喉 | 519篇 |
儿科学 | 1140篇 |
妇产科学 | 1165篇 |
基础医学 | 6074篇 |
口腔科学 | 1124篇 |
临床医学 | 6268篇 |
内科学 | 10892篇 |
皮肤病学 | 1076篇 |
神经病学 | 3246篇 |
特种医学 | 1217篇 |
外国民族医学 | 6篇 |
外科学 | 6208篇 |
综合类 | 6158篇 |
现状与发展 | 2篇 |
一般理论 | 9篇 |
预防医学 | 4692篇 |
眼科学 | 1284篇 |
药学 | 4955篇 |
52篇 | |
中国医学 | 2283篇 |
肿瘤学 | 3154篇 |
出版年
2024年 | 141篇 |
2023年 | 666篇 |
2022年 | 1501篇 |
2021年 | 2674篇 |
2020年 | 1869篇 |
2019年 | 1814篇 |
2018年 | 1998篇 |
2017年 | 1760篇 |
2016年 | 1500篇 |
2015年 | 2200篇 |
2014年 | 2917篇 |
2013年 | 3392篇 |
2012年 | 5042篇 |
2011年 | 5091篇 |
2010年 | 3431篇 |
2009年 | 2962篇 |
2008年 | 3625篇 |
2007年 | 3556篇 |
2006年 | 3094篇 |
2005年 | 2810篇 |
2004年 | 2197篇 |
2003年 | 2072篇 |
2002年 | 1678篇 |
2001年 | 468篇 |
2000年 | 380篇 |
1999年 | 325篇 |
1998年 | 282篇 |
1997年 | 258篇 |
1996年 | 230篇 |
1995年 | 183篇 |
1994年 | 152篇 |
1993年 | 119篇 |
1992年 | 109篇 |
1991年 | 82篇 |
1990年 | 84篇 |
1989年 | 74篇 |
1988年 | 65篇 |
1987年 | 57篇 |
1986年 | 55篇 |
1985年 | 52篇 |
1984年 | 46篇 |
1983年 | 44篇 |
1982年 | 58篇 |
1981年 | 66篇 |
1980年 | 37篇 |
1979年 | 43篇 |
1978年 | 22篇 |
1977年 | 32篇 |
1976年 | 33篇 |
1975年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Mnica De la Fuente Juan Jos Garrido Rosa María Arahuetes Angel Hernanz 《Journal of neuroimmunology》1993,42(1)
The neuropeptides neurotensin and neuromedin N (from 10−12 M to 10−9 M) have been showed in this study to stimulate significantly in vitro several steps of the phagocytic process: adherence to substrate, chemotaxis, ingestion of inert particles (latex beads) and production of superoxide anion measured by nitroblue tetrazolium reduction in resting peritoneal macrophages from BALB/c mice. A dose-response relationship was observed, with a maximal stimulation of the phagocytic process at 10−11 M. The two neuropeptides induced no change of intracellular cyclic AMP in murine macrophages. Moreover, adherence and chemotaxis decreased significantly in the presence of EGTA (1 mM), a chelator of extracellular Ca2+, or ryanodine (0.5 mM), a blocker of a Ca2+-gated channel from the endoplasmic reticulum, in both controls and samples with the addition of neurotensin or neuromedin N. These results suggest that there is no relation between the cAMP messenger system and the phagocytic process stimulation in murine peritoneal macrophages by neurotensin or neuromedin N. In addition, the results observed with EGTA and ryanodine could indicate that these two neuropeptides produce their effects through an increase of intracellular Ca2+ concentration. 相似文献
82.
Juan C. Kupferman Charles L. Stewart Frederick J. Kaskel Richard N. Fine 《Pediatric nephrology (Berlin, Germany)》1996,10(2):143-146
Renal and urological anomalies in Down syndrome (DS) have received little attention compared with the nephrourological findings described in other chromosomal abnormalities. Renal hypoplasia, hydroureteronephrosis, ureterovesical and ureteropelvic junction obstruction, and vesicoureteral reflux, but not posterior urethral valves, have been associated with DS. We report the occurrence of posterior urethral valves in three male infants with DS at a single institution. All had multiple urological procedures for correction or palliation of obstruction. Children with DS may have an increased risk for developing posterior urethral valves and obstructive uropathy. Furthermore, they may also develop chronic renal failure secondary to posterior urethral valves. Therefore, we suggests that infants with DS be screened with ultrasonography for renal and urological abnormalities early in life and, if abnormal, a contrast voiding cystourethrogram be performed to rule out posterior urethral valves or other bladder or urethral abnormalities. A review of the renal and urological anomalies in DS reported in the literature since 1960 is presented. 相似文献
83.
不同术后镇痛模式对红细胞免疫功能的影响 总被引:4,自引:1,他引:3
目的探讨不同术后镇痛模式对红细胞免疫功能的影响。方法50例妇科手术患者,按术后不同镇痛模式分为硬膜外自控镇痛(PCEA)组和静脉自控镇痛(PCIA)组。并分别于术前、术后1、3、7 d采静脉血样检测红细胞C3b受体花环率(RCR)、红细胞免疫复合物花环率(RICR)、红细胞免疫粘附促进因子(RFER)和红细胞免疫粘附抑制因子(RFIR)。结果与术前比,PCEA组术后1 d RCR、RFER显著上升(P<0.05),RFIR显著下降(P<0.05),术后3 d RCR、RFER仍显著上升(P<0.05),而RICR显著下降(P<0.05);PCIA组术后1 d RCR、RFER显著下降(P<0.05),RFIR、RICR显著上升(P<0.05);PCIA组术后1、3 d RCR、RFER比PCEA组显著降低(P<0.05),而RICR显著上升(P<0.05);两组各参数在术后7 d基本恢复至术前水平。结论PCEA对红细胞免疫功能的稳定和恢复作用明显强于PCIA。 相似文献
84.
蕲蛇酶减轻大鼠局灶性脑缺血再灌注损伤的实验研究(Ⅱ) 总被引:2,自引:0,他引:2
目的 从病理形态学观察蕲蛇酶对大鼠局灶性脑缺血再灌注损伤的保护作用并探讨其机制。方法 采用线栓法制备大鼠大脑中动脉栓塞后再灌注模型,光镜及电镜观察缺血3h恢复血流再灌24h后脑组织形态学变化。TTC染色观察脑梗死面积,免疫组织化学方法检测脑组织碱性成纤维细胞生长因子(bFGF)的表达。用药组分别在缺血即刻或再灌即刻静脉给予不同剂量的蕲蛇酶,观察比较模型组和蕲蛇酶所有给药组之间上述指标的变化。结果 缺血即刻给蕲蛇酶4U/kg组较再灌即刻给蕲蛇酶同剂量组显著减小梗死灶(P〈0.001),减轻脑组织病理改变,并使脑组织中bFGF蛋白表达明显增多。结论 蕲蛇酶对脑缺血再灌注损伤的神经保护作用可能与脑组织中bFGF表达增高有关;提示该药早期使用更为有效。 相似文献
85.
Alicia Gómez-Barrio David Montero-Pereira Juan J. Nogal-Ruiz José A. Escario Susana Muelas-Serrano Vladimir V. Kouznetsov Leonor Y. Vargas Méndez Juan M. Urbina Gonzáles Carmen Ochoa 《Acta parasitologica / Witold Stefański Institute of Parasitology, Warszawa, Poland》2006,51(1):73-78
A study of some antiparasitic properties of several homoallylamines and related tetrahydroquinolines and quinolines, previously
described, was carried out using in vitro activity assays against the epimastigote form of Trypanosoma cruzi and against Trichomonas vaginalis. Unspecific cytotoxicity against murine macrophages was also studied. Although the antichagasic and trichomonacidal activities
are not comparable to those of the standard drugs, nifurtimox and metronidazole, some of the compounds exhibit an interesting
specific antiparasitic activity. 相似文献
86.
87.
Carlos Bada Nilton Yhuri Carreazo Juan Pablo Chalco Luis Huicho 《Revista paulista de medicina》2007,125(3):150-154
CONTEXT AND OBJECTIVE: Many children with acute lower respiratory tract infections (ALRI) present to the emergency ward with concurrent wheezing. A chest x-ray is often requested to rule out pneumonia. We assessed inter-observer agreement in interpreting x-rays on such children. DESIGNS AND SETTING: Prospective consecutive case study at Instituto de Salud del Ni?o, Lima, Peru. METHODS: Chest x-rays were obtained from eligible children younger than two years old with ALRI and concurrent wheezing who were seen in the emergency ward of a nationwide pediatric referral hospital. The x-rays were read independently by three different pediatric residents who were aware only that the children had a respiratory infection. All the children had received inhaled beta-adrenergic agonists before undergoing chest x-rays. Lobar and complicated pneumonia cases were excluded from the study. RESULTS: Two hundred x-rays were read. The overall kappa index was 0.2. The highest individual kappa values for specific x-ray findings ranged from 0.26 to 0.34 for rib horizontalization and from 0.14 to 0.31 for alveolar infiltrate. Inter-observer variation was intermediate for alveolar infiltrate (kappa 0.14 to 0.21) and for air bronchogram (kappa 0.13 to 0.23). Reinforcement of the bronchovascular network (kappa 0.10 to 0.16) and air trapping (kappa 0.05 to 0.20) had the lowest agreement. CONCLUSIONS: There was poor inter-observer agreement for chest x-ray interpretation on children with ALRI and concurrent wheezing seen at the emergency ward. This may preclude reliable diagnosing of pneumonia in settings where residents make management decisions regarding sick children. The effects of training on inter-observer variation need further studies. 相似文献
88.
反式二羟环氧苯并芘对人支气管上皮细胞中HER2/neu基因表达的影响 总被引:1,自引:0,他引:1
目的探讨环境致癌物苯并(a)芘代谢物反式二羟环氧苯并芘(BPDE)对人支气管上皮细胞HER2/neu基因表达的影响。方法利用半定量RT-PCR、SYBR GreenI实时定量RT-PCR(QRT-PCR)、Western blot及免疫细胞化学方法分别检测经2.0μmol/L反式BPDE诱发人支气管上皮细胞恶性转化细胞(16HBE-T)与对照DMSO溶剂组未恶性转化细胞(16HBE-N)之间HER2/neu基因mRNA和蛋白表达水平的差异,及两组细胞内HER2/neu蛋白表达定位分析。结果经几种不同方法检测反式BPDE恶性转化人支气管上皮细胞中HER2/neu基因mRNA和蛋白水平都比对照溶剂组细胞(16HBE-N)表达显著升高(P<0.05)。HER2/neu蛋白定位在胞膜。结论反式BPDE诱发人支气管上皮细胞恶性转化存在HER2/neu表达增高,其可能与原癌基因HER2/neu被激活作用有关。 相似文献
89.
Thanks to screening programs and high-resolution ultrasound equipment, lung developmental malformations are readily diagnosed. Given the variable consequences of these conditions, reliable methods are needed to predict the mortality as well as the level of morbidity associated with the diagnosed malformation. New ultrasonographic methods (improvement of 2D ultrasound machine's resolution, measurement of lung volume by 3D ultrasonography (Virtual Organ Computer-aided Analysis (VOCAL) imaging program), Volume Contrast Imaging and 3D power Doppler) improved the understanding of pathologies natural history as well as prognosis evaluation. MRI is still the reference technique but the use of 3D ultrasonography tends to generalize. Recent improvement in prognostic evaluation lead to minimally invasive in utero treatment for human fetuses with CDH. Tracheal occlusion is performed through the use of a balloon placed by foetoscopy. First results are encouraging in terms of mortality. Evaluation of induced short and long morbidity is still needed. 相似文献
90.
探讨安徽省立医院规范临床新技术、新项目管理的做法:一是明确新技术、新项目的管理范畴和管理部门;二是抓好申报与管理的三个环节;三是管理与激励并重,实现两个效益稳步增长.并结合三年来的实践谈自身体会. 相似文献