全文获取类型
收费全文 | 443133篇 |
免费 | 42361篇 |
国内免费 | 23374篇 |
专业分类
耳鼻咽喉 | 4255篇 |
儿科学 | 7675篇 |
妇产科学 | 3515篇 |
基础医学 | 28570篇 |
口腔科学 | 7743篇 |
临床医学 | 51534篇 |
内科学 | 43343篇 |
皮肤病学 | 5395篇 |
神经病学 | 11560篇 |
特种医学 | 17085篇 |
外国民族医学 | 2篇 |
外科学 | 39623篇 |
综合类 | 115191篇 |
现状与发展 | 94篇 |
一般理论 | 1篇 |
预防医学 | 49619篇 |
眼科学 | 5306篇 |
药学 | 53790篇 |
674篇 | |
中国医学 | 43189篇 |
肿瘤学 | 20704篇 |
出版年
2024年 | 2186篇 |
2023年 | 5618篇 |
2022年 | 13883篇 |
2021年 | 17748篇 |
2020年 | 15458篇 |
2019年 | 8694篇 |
2018年 | 9148篇 |
2017年 | 12243篇 |
2016年 | 9378篇 |
2015年 | 17044篇 |
2014年 | 21900篇 |
2013年 | 27859篇 |
2012年 | 39824篇 |
2011年 | 42411篇 |
2010年 | 37597篇 |
2009年 | 32983篇 |
2008年 | 34656篇 |
2007年 | 33448篇 |
2006年 | 29466篇 |
2005年 | 23469篇 |
2004年 | 17011篇 |
2003年 | 13796篇 |
2002年 | 10742篇 |
2001年 | 9789篇 |
2000年 | 7606篇 |
1999年 | 3484篇 |
1998年 | 947篇 |
1997年 | 725篇 |
1996年 | 732篇 |
1995年 | 592篇 |
1994年 | 571篇 |
1993年 | 389篇 |
1992年 | 821篇 |
1991年 | 689篇 |
1990年 | 632篇 |
1989年 | 620篇 |
1988年 | 519篇 |
1987年 | 518篇 |
1986年 | 500篇 |
1985年 | 378篇 |
1984年 | 304篇 |
1983年 | 257篇 |
1982年 | 167篇 |
1979年 | 222篇 |
1978年 | 130篇 |
1977年 | 113篇 |
1974年 | 123篇 |
1973年 | 127篇 |
1972年 | 122篇 |
1971年 | 110篇 |
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
51.
管状膨体聚四氟乙烯用于组织工程支架材料的动物实验研究 总被引:6,自引:0,他引:6
目的:研究膨体聚四氟乙烯(ePTFE)植入动物体内后与机体的关系。方法:管状膨体聚四氟乙烯两端闭合,内充DMEM培养液,埋入家兔皮下,观察宿主生命情况,于术后1、2、4、6周取出标本,行大体及光镜下观察。结果:家兔在植入膨体聚四氟乙烯材料及DMEM培养液后存活情况良好,DMEM培养液在1周时即已完全无色透明;4周时膨体聚四氟乙烯与周围组织有粘连,6周时粘连紧密;光镜下观察,各时间点材料间隙均可见着色,1周时可见少量淋巴细胞浸润,无血管及组织细胞。材料内壁未见细胞附着。结论:植入膨体聚四氟乙烯材料及少量DMEM培养液对宿主动物存活无影响;管内外液体可相互交通,管状膨体聚四氟乙烯可作为组织工程化尿道的支架材料。 相似文献
52.
Correlation of serum metalloproteinase levels with lung cancer metastasis and response to therapy. 总被引:14,自引:0,他引:14
S Garbisa G Scagliotti L Masiero C Di Francesco C Caenazzo M Onisto M Micela W G Stetler-Stevenson L A Liotta 《Cancer research》1992,52(16):4548-4549
Cancer cells elaborate metalloproteinases which may play a role in invasion and metastasis. The serum level of the M(r) 72,000 type IV collagenase (MMP-2) was measured in 87 lung cancer patients. Stage IV cancer levels were significantly elevated (P less than 0.0001) compared to normal sera. A significant difference (P less than 0.01) was found between enzyme levels in the presence versus the absence of distant metastasis. For 29 patients treated with combination chemotherapy, a positive relationship was noted between response failure and elevated enzyme levels. Serum metalloproteinase levels may provide information relevant to prognosis as well as treatment decisions. 相似文献
53.
Sylvie Di Filippo Bertrand Semiond Ricardo Roriz Francois Sassolas Marie José Raboisson André Bozio 《The Journal of heart and lung transplantation》2003,22(8):876-882
BACKGROUND: Coronary vasculopathy is the main cause of cardiac graft failure. Because yearly coronary angiography is invasive in children, a non-invasive method for detecting graft vasculopathy is needed. The aim of this study was to test dobutamine-stress echocardiography in a pediatric population to determine its feasibility, safety and reliability in the detection of graft coronary artery disease. METHODS: Eighteen patients, aged 2 days to 16.8 years at transplantation (mean 8.4 years), underwent 44 dobutamine-stress echocardiography (DSE) exams, at a follow-up of 1.1 to 11.8 years (mean 5.1 years). Selective coronary angiography was performed for comparison. Echocardiographic recordings were obtained in 4 standard views of the left ventricle and measurements carried out within the frames of a 16-segment model. Segmental scores of contractility were obtained for each segment and a total segmental contractility index was calculated at each stage. RESULTS: All patients reached the maximum dose stage. Maximum heart rate was 57% to 90% of predicted maximum. Maximum systolic blood pressure reached 190 mmHg. Segmental scores were normal in 37 and abnormal in 7 cases. Echographic results were concordant with angiography in 82% and discordant in 18% of the cases (4 negative DSEs with minor angiographic lesions, 2 positive DSEs with normal angiography), but there was no significant angiographic lesion with normal DSE. CONCLUSIONS: DSE is a safe and highly feasible non-invasive technique in transplanted children. A normal DSE study successfully predicts the absence of significant coronary artery disease in the post-transplant population. 相似文献
54.
载脂蛋白E基因多态性与脑梗死的相关性分析 总被引:12,自引:0,他引:12
目的 探讨载脂蛋白 E基因多态性与脑梗死的关系。方法 通过聚合酶链反应 -限制性片段长度多态性 (PCR- RFL P)分析结合 DNA直接银染技术检测 6 6例脑梗死 (CI)患者的载脂蛋白 E(Apo E)基因型 (其中家系中有明确脑梗死先证者的家族聚集性脑梗死 (FMACI)亚组 2 6例 ,家系中无脑卒中史的非家族聚集性脑梗死 (NF-MACI)亚组 4 0例 ) ,并与 90例健康对照组比较 ,同时检测血脂、脂蛋白 (a) [L P(a) ]及部分载脂蛋白。结果 脑梗死组ε3/4基因型频率明显高于对照组 (P<0 .0 1) ,ε3/3基因型频率明显低于对照组 (P<0 .0 1) ;两脑梗死亚组之间的ε3/4/ε3/3基因型频率虽有上升 /下降趋势 ,但未发现明显的统计学差异 ;FMACI组高密度脂蛋白 (HDL )水平明显低于 NFMACI组 (P<0 .0 5 )。结论 Apo E基因多态性与脑梗死的发生有关 ,ε4等位基因是脑梗死的易感因子 ,ε3等位基因对脑梗死的发生有保护作用 ;Apo E基因多态性和 HDL水平双重作用于家族聚集性脑梗死的发生。 相似文献
55.
目的 探讨近端/远端复合肌肉动作电位振幅比率在术后面神经肿瘤侵犯段功能评估上的价值和对早期面神经修复的指导意义。方法 比较术末面神经近端/远端复合肌肉动作电位振幅比率和术后2周、6个月患侧面神经功能的H-B分级之间的关系。结果 术后6个月面神经H-B分级恢复到Ⅰ-Ⅱ级者,术末近端/远端复合肌肉动作电位振幅比率均>0.3。结论 术末面神经近端/远端复合肌肉动作电位振幅比率是判断术后面神经远期功能,特别是肿瘤侵犯段功能的重要指标,为术中直接修复面神经提供了指导依据。 相似文献
56.
A Vetrani F Fulciniti G Di Benedetto P Zeppa G Troncone A Boscaino G de Rosa L Palombini 《Cancer》1992,69(3):736-740
A series of 1153 fine-needle aspiration biopsies (FNAB) of breast masses obtained during the period 1985 to 1988 in one institution was examined. The following diagnostic accuracy values were found: sensitivity, 93.0%; specificity, 92.4%; predictive positive value, 93.7%; and efficiency, 92.8%. These results were compared with a previously published series for the period 1976 to 1984. The diagnostic accuracy values did not differ significantly between the two series. 相似文献
57.
Repetitive conservative surgery for recurrence of endometriosis 总被引:4,自引:0,他引:4
G B Candiani L Fedele P Vercellini S Bianchi G Di Nola 《Obstetrics and gynecology》1991,77(3):421-424
We evaluated the recovery of fertility and the relief of pain symptoms in a long-term follow-up of 42 women undergoing repetitive conservative surgery for recurrent endometriosis. The mean age of the patients was 31.1 +/- 4.3 years. At the time of their second operation the disease was stage IV in 14 women, stage III in 25, and stage I in three. After reoperation, the patients were followed for a mean period of 41.8 +/- 30.3 months. Pain symptoms returned in eight women, dysmenorrhea and deep dyspareunia in eight, and pelvic pain in seven. Eight of the 28 women (28.6%) who attempted to conceive achieved a total of 13 pregnancies. The corrected pregnancy rate was 35%, and the cumulative rate at 27 months was 30.7%. A third operation was necessary in six women after a mean period of 35 months. Conservative surgery is an effective therapeutic option for infertile patients with recurrent endometriosis. 相似文献
58.
Central sensory and motor conduction in vitamin B12 deficiency. 总被引:7,自引:0,他引:7
V Di Lazzaro D Restuccia D Fogli R Nardone S Mazza P Tonali 《Electroencephalography and clinical neurophysiology》1992,84(5):433-439
Four patients with subacute combined degeneration were studied through upper and lower limb SEPs recorded with a non-cephalic reference montage and through cortical and spinal magnetic stimulation. Clinical signs were confined to the lower limbs in 3 patients; the remaining patient presented only paraesthesiae in 4 limbs. Median nerve SEPs showed a normal cervical N13 response with a significant increase of central conduction time concerning exclusively the P9-P14 interpeak interval. Central motor conduction to upper and lower limb muscles was abnormal. Nerve conduction studies provided no evidence of peripheral nerve involvement. These electrophysiological findings suggest that in vitamin B12 deficiency the higher segments of the cervical cord are usually affected first and that central sensory and motor conduction studies are sensitive methods for detecting such damage. 相似文献
59.
白细胞介素—2新的功能位点及其中枢镇痛作用 总被引:2,自引:0,他引:2
白细胞介素-2(IL-2)不仅是重要的免疫调节因子,而且还具有重要的中枢调节作用。本实验以钾离子透入引起大鼠甩尾反应为指标,发现侧脑室注射IL—2能显著提高动物痛阈,并能被纳洛酮所阻断,表示IL-2的中枢镇痛作用可能与阿片受体有关。利用基因定位突变技术获得的无免疫活性IL-2实查体仍具有中枢镇痛作用,表明IL—2分子上发挥镇痛和免疫调节作用的功能位点是相互独立的。纳洛酮能够阻断IL—2的中枢镇痛作用,而不能影响IL—2增殖CTLL-2细胞的作用,提示IL-2发挥镇痛和免疫调节作用可能通过不同的受体途径。IL-2分子中第45位Tyr残基突变为Val后,虽仍保留了免疫活性,但丧失了镇痛功能,表示45位Tyr残基是IL—2发挥中枢镇痛功能的关键残基之一。我们推测IL—2的镇痛功能位点可能在IL—2分子中第45位Tyr残基附近区域。 相似文献
60.
B B Toner E Koyama P E Garfinkel K N Jeejeebhoy I Di Gasbarro 《International journal of psychiatry in medicine》1992,22(1):99-103
The Marlowe-Crowne Social Desirability Scale, a 33-item self-report questionnaire, was administered to an age-matched sample of twenty-five irritable bowel syndrome (IBS) patients, twenty-four psychiatric patients meeting a diagnosis of major depression, and nineteen controls. As predicted, planned comparisons analysis showed a significant group effect: IBS group scores were significantly higher than both depressed and control group scores (p less than .05). Implications of this social desirability response set for the psychological assessment and treatment of IBS are discussed. 相似文献