全文获取类型
收费全文 | 174767篇 |
免费 | 17556篇 |
国内免费 | 10069篇 |
专业分类
耳鼻咽喉 | 1497篇 |
儿科学 | 2649篇 |
妇产科学 | 1041篇 |
基础医学 | 11854篇 |
口腔科学 | 3337篇 |
临床医学 | 21060篇 |
内科学 | 16090篇 |
皮肤病学 | 1811篇 |
神经病学 | 4519篇 |
特种医学 | 6061篇 |
外国民族医学 | 11篇 |
外科学 | 15901篇 |
综合类 | 46982篇 |
现状与发展 | 42篇 |
预防医学 | 20270篇 |
眼科学 | 2388篇 |
药学 | 21225篇 |
216篇 | |
中国医学 | 16831篇 |
肿瘤学 | 8607篇 |
出版年
2025年 | 23篇 |
2024年 | 2437篇 |
2023年 | 2648篇 |
2022年 | 5879篇 |
2021年 | 6990篇 |
2020年 | 6127篇 |
2019年 | 3709篇 |
2018年 | 3680篇 |
2017年 | 4778篇 |
2016年 | 3815篇 |
2015年 | 6686篇 |
2014年 | 8845篇 |
2013年 | 10535篇 |
2012年 | 15186篇 |
2011年 | 15827篇 |
2010年 | 14342篇 |
2009年 | 12846篇 |
2008年 | 13247篇 |
2007年 | 12941篇 |
2006年 | 11808篇 |
2005年 | 9535篇 |
2004年 | 7013篇 |
2003年 | 5909篇 |
2002年 | 4647篇 |
2001年 | 4244篇 |
2000年 | 3210篇 |
1999年 | 1563篇 |
1998年 | 549篇 |
1997年 | 592篇 |
1996年 | 467篇 |
1995年 | 397篇 |
1994年 | 343篇 |
1993年 | 244篇 |
1992年 | 212篇 |
1991年 | 181篇 |
1990年 | 184篇 |
1989年 | 138篇 |
1988年 | 99篇 |
1987年 | 118篇 |
1986年 | 81篇 |
1985年 | 71篇 |
1984年 | 38篇 |
1983年 | 42篇 |
1982年 | 28篇 |
1981年 | 15篇 |
1959年 | 15篇 |
1958年 | 19篇 |
1957年 | 14篇 |
1955年 | 7篇 |
1954年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
SONG Wu WU Sui-jing HE Yu-long CAI Shi-rong ZHANG Chang-hua ZHANG Xin-hua ZHAN Wen-hua 《中华医学杂志(英文版)》2001,122(1):1486-1491
Background Previous studies have shown conflicting results on the relation between clinicopathologic features and prognosis of patients with colorectal mucinous, signet-ring cell, or non-mucinous adenocarcinoma; only few such studies have been performed in China. This retrospective study analyzed data from our department to investigate clinicopathologic characteristics, prognosis and possible correlations of three histologic types -- colorectal mucinous,signet-ring cell, and non-mucinous adenocarcinoma, to clarity the bases for observed differences which may lead to development of targeted therapies Methods Of 2079 patients diagnosed with colorectal cancer between 1994 and 2007, 144 had mucinous, 25 had signet-ring cell, and 1837 had non-mucinous adenocarcinoma. Their clinicopathologic parameters and survival were analyzed using established statistical methodologies.Results Mucinous and signet-ring cell adenocarcinomas were common in younger patients (P <0.001). Location, size and disease stage differed significantly among the three types. Signet-ring cell tumors were more commonly found in the rectum than mucinous and non-mucinous adenocarcinoma (P <0.001). Mucinous and signet-ring cell tumors presented in a later stage in life more often than non-mucinous adenocarcinoma, with lymph node involvement, serosal infiltration, peritoneal dissemination, and adjacent organ invasion (P <0.01). The rate of radical resection, hepatic metastasis and local recurrence did not differ among types (P >0.05). Compared with patients with non-mucinous adenocarcinoma, patients with mucinous and signet-ring cell tumors who underwent potentially curative resections or stage Ⅱ/Ⅲ disease had poorer long-term overall survival. Survival did not differ by type for patients with either stage Ⅰor Ⅳ disease (P >0.05). Conclusions Mucinous and signet-ring cell adenocarcinoma have unique carcinogenesis and similar biologic behavior.Our study confirms that both histologic types, especially signet-ring cell tumors, are independent, negative prognostic factors for patients with colorectal cancer. Type does not appear to have a significant effect on survival when disease is either stage Ⅰ or Ⅳ at presentation. 相似文献
102.
CHENG Yu-tong YANG Yue-jin ZHANG Hai-tao QIAN Hai-yan ZHAO Jing-lin MENG Xian-min LUO Fu-liang WU Yi-ling 《中华医学杂志(英文版)》2001,122(1):1529-1538
Background The traditional Chinese medicine Tongxinluo can protect myocardium against ischaemia/reperfusion injury, but the mechanism of its action is not well documented. We examined the involvement of nitric oxide in the protective role of Tongxinluo. Methods Miniswine were randomized to four groups of seven: sham, control, Tongxinluo and Tongxinluo coadministration with a nitric oxide synthase inhibitor Nω-nitro-L-arginine (L-NNA, 10 mg/kg i.v.). Three hours after administration of Tongxinluo, the animals were anaesthetised and the left anterior descending coronary artery ligated and maintained in situ for 90 minutes followed by 3 hours of reperfusion before death. Area of no reflow and necrosis and risk region were determined pathologically by planimetry. The degree of neutrophil accumulation in myocardium was obtained by measuring myeloperoxidase activity and histological analysis. Myocardial endothelial nitric oxide synthase activity and vascular endothelial cadherin content were measured by colorimetric method and immunoblotting analysis respectively.Results Tongxinluo significantly increased the local blood flow and limited the infarct and size of no reflow. Tongxinluo also attenuated myeloperoxidase activity and neutrophil accumulation in histological sections and maintained the level of vascular endothelial cadherin and endothelial nitric oxide synthase activity in the reflow region when compared with control group. The protection of Tongxinluo was counteracted by coadministration with L-NNA. Conclusions Tongxinluo may limit myocardial ischaemia and protect the heart against reperfusion injury. Tongxinluo regulates synthesis of nitric oxide by altering activity of endothelial nitric oxide synthase. 相似文献
103.
普罗布考对体外培养的主动脉平滑肌细胞NF—kB活性的影响 总被引:3,自引:0,他引:3
目的:观察普罗布考(probucol)对血管平滑肌细胞(VSMCs)核因子kB(NF-kB)活性的调控作用,以探讨probucol在动脉粥样硬化(AS)和经皮腔内冠状动脉成形术后再狭窄(RS)防治中的某些可能的作用机制。方法:采用电泳迁移位移测定法观察probucol对VSMCsNF-kB活性的影响。结果:H2O2或胎牛血清(NCS)处理VSMCs72h后,NF-kB活性均明显增强;而加入100umol/Lprobucol后,NF-kB活性受到部分抑制,抑制率分别为37.1%和14.8%。结论:Probucol抑制NCS、H2O2诱导的VSMCsNF-kB的活性,可能是其临床有效防治RS及AS的作用机制之一。 相似文献
104.
Radiofrequencyablation(RFA)isarecentlyde-velopedsystemthatprovidesanewapproachforthetreatmentofpatientswithunresectablemalignanttu-mor.Aninsulatedneedleelectrodethatcontains10fineneedleswithinentersthetumortissueunderCTguidanceandthe10fineneedlesstretchasanumbrel-lacoveringanareaapproximately3.5cmindiameter,beforearadiofrequencygeneratortransmitshigh-en-ergyradiofrequencypulsesthroughthewiretothefineneedles.Theenergyreleasedattheneedlepointcantriggerionicagitationandfrictionalheattopro-ducea… 相似文献
105.
106.
重组人钙调素对白芷细胞增殖及结核杆菌生长的影响 总被引:1,自引:1,他引:0
目的 :探讨重组人钙调素 ( rh Ca M)对白芷悬浮细胞及结核杆菌增殖作用的影响。 方法 :用基因重组技术获得人钙调素基因 ( h Ca M c DNA)重组表达质粒 h Ca M / p BV2 2 0 ,将其转化大肠杆菌 DH5α。用 Phenyl-Sepharose CL -4 B疏水亲和层析法纯化重组菌超声上清表达产物。将纯化 rh Ca M加入悬浮培养的白芷细胞及结核杆菌培养基中 ,观察 rh Ca M对其增殖作用的影响。 结果 :含 h Ca M / p BV2 2 0的重组菌经温度诱导可高效表达Ca M蛋白 ,经 15 % SDS-PAGE分析 ,可观察到一相对分子质量为 170 0 0的表达条带 ,Western blot结果证实 ,此表达条带可与标准鼠抗 Ca M Mc Ab起特异反应。每 1L菌液经 Phenyl-Sepharose CL -4 B疏水亲和层析法纯化可获Ca M纯品 3~ 4mg。rh Ca M对白芷细胞增殖作用影响的研究结果表明 ,rh Ca M在低细胞密度培养条件下对白芷细胞有促进增殖作用 ,效果高于标准植物 Ca M。本研究同时还发现一定浓度的纯化 rh Ca M( 1、10μg/ ml)可促进牛型结核杆菌的生长。 结论 :rh Ca M对植物细胞和细菌均有细胞外促增殖作用 相似文献
107.
采用溶剂萃取-化学处理-柱层析相结合的预处理分离程序、色-质联用和色-红联用结合色谱保留值的定性方法,分析研究了内蒙东胜煤快速加氢热解焦油的化学成分和结构,推测鉴定出200多种化合物,并对具有代表性的19种多环芳烃进行了定量分析,讨论了快速加氢热解焦油化学成分的结构特征。 相似文献
108.
应用原位分子杂交技术研究卵巢恶性肿瘤组织中VEGFmRNA和bFGFmRNA的表达及其意义。结果发现 :浆液性腺癌和内胚窦癌两者表达阳性率高于粘液性腺癌和颗粒细胞瘤 ;临床分期Ⅰ期和未转移病例两者表达阳性率低于临床分期Ⅲ~Ⅳ期和转移病例。结果提示VEGFmRNA和bFGFmRNA表达与卵巢恶性肿瘤病理类型、临床分期和转移发生关系密切 ,阳性表达者可能预后较差。 相似文献
109.
不同地区妇女产褥期卫生行为研究 总被引:22,自引:0,他引:22
目的 了解江苏、陕西和贵州三省妇女产褥期卫生行为和保健的一般情况;比较 不同地区间产褥期各种卫生行为的发生率;了解影响产褥期卫生行为的相关因素。方法 用问卷调查的形式对三者12个县的2352例2岁以下儿童母亲进行入户访问。结果 江苏、陕西、贵州三者产褥期各卫生行为的发和衣次为:洗头26.4%,38.8%,19.8%, 下身(指外阴部,下同)83.3%,26.9%,64.0%,正常活动76.9%,7 相似文献
110.
目的:探讨P75NGFR介导神经细胞凋亡的分子机制。方法;以转染了P75NGFR的大鼠小脑神经细胞株R2L2为细胞模型,应用酵母双向杂交系统(two-hybrid system)筛选和鉴定P75NGFR胞内区P75ICD作用的蛋白。结果:和P75NGFR作用的蛋白由一个600bp大小的CDNA片段编码。结论:该工作将有助于探讨P75NGFR介导细胞凋亡的分子机制和信号,为勃勃系统退行性病变的病因、 相似文献