首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   163274篇
  免费   16097篇
  国内免费   10947篇
耳鼻咽喉   1727篇
儿科学   2267篇
妇产科学   1376篇
基础医学   15077篇
口腔科学   2877篇
临床医学   20048篇
内科学   20099篇
皮肤病学   1931篇
神经病学   6502篇
特种医学   6273篇
外国民族医学   68篇
外科学   16861篇
综合类   35517篇
现状与发展   49篇
一般理论   10篇
预防医学   13626篇
眼科学   3653篇
药学   17396篇
  187篇
中国医学   12579篇
肿瘤学   12195篇
  2024年   538篇
  2023年   2102篇
  2022年   5342篇
  2021年   7669篇
  2020年   6143篇
  2019年   4623篇
  2018年   5077篇
  2017年   5181篇
  2016年   4866篇
  2015年   7780篇
  2014年   9494篇
  2013年   9902篇
  2012年   14293篇
  2011年   15343篇
  2010年   11599篇
  2009年   9685篇
  2008年   10860篇
  2007年   10403篇
  2006年   9751篇
  2005年   8258篇
  2004年   5856篇
  2003年   5507篇
  2002年   4520篇
  2001年   3430篇
  2000年   2656篇
  1999年   2012篇
  1998年   1182篇
  1997年   1137篇
  1996年   895篇
  1995年   803篇
  1994年   615篇
  1993年   383篇
  1992年   405篇
  1991年   325篇
  1990年   300篇
  1989年   237篇
  1988年   206篇
  1987年   187篇
  1986年   146篇
  1985年   115篇
  1984年   59篇
  1983年   54篇
  1982年   38篇
  1981年   41篇
  1980年   25篇
  1979年   42篇
  1977年   26篇
  1976年   21篇
  1974年   22篇
  1973年   29篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
美国作为世界上经济最发达的国家,2005年其医疗卫生的总支出已占GDP的16%,高居全球之首,但是美国迄今尚有15.2%的人群没有医疗保险。如何解决这个问题,最近,马萨诸塞州出台了新措施:通过立法强制未参保人群参保。这种做法或许会对中国当前正在进行的医疗卫生体制改革有所启发。  相似文献   
172.
173.
Monoclonal antibody 131I-COC183B2, developed in our laboratory and proved to fit for human treatment was injected intraperitoneally or subcutaneously in 13 patients. In 8 cases with i.p. injection the disease corresponded with the image, i.e. 3 primary ovarian epithelial cancers showed positive images, 1 ovarian Krukenberg tumor was negative and the other 4 negative images included 1 uterine myoma and 3 ovarian teratomas. In the subcutaneous injection group, 4 cases had ovarian carcinoma, surgery and chemotherapy. Two negative images corresponded with the clinical status-in good health, another negative case had metastatic left supraclavicular lymph node due to ovarian mucinous adenocarcinoma. The last negative image in this group was a case of benign ovarian teratoma which was proved after surgery. The 1 positive case was waiting to be proved by a scheduled third operation. The computer scintigram calculation of T/NT was 5.35 to 13.7. The results suggest that this monoclonal antibody can be used for radioimmunoimaging for the localization of ovarian carcinoma, which is not only helpful for clinical staging and differential diagnosis but is also a good follow-up method.
  相似文献   
174.
纳米血管生成素-2小干扰RNA质粒制备及功能研究   总被引:2,自引:0,他引:2  
[目的]制备血管生成素-2小干扰RNA(Ang-2siRNA)质粒纳米微粒,并观察其基因转染能力和基因沉默效果.[方法]应用分子克隆的方法构建Ang-2siRNA质粒,将其与聚乳酸、O羧甲基壳聚糖用水/油/水(W/O/W)双乳化溶剂蒸发法制备纳米微球,扫描电镜观察其形态和粒径.然后转染原代人脐带静脉内皮细胞,观察纳米Ang-2siRNA微粒干扰Ang-2基因表达的效果及其细胞保护功能.[结果]扫描电镜观察到Ang2siRNA纳米微球呈球形和椭球形,粒径150~200 nm,大小分布均匀,包封完整,分散性良好.有较强转基因能力,良好的RNA干扰效果和血管内皮细胞保护功能.[结论]成功制备纳米Ang-2siRNA微粒,并证实其载基因能力和RNA干扰效果,对血管内皮细胞损伤因素有良好保护作用,为进一步研究心肌梗死的血管修复机制奠定了坚实的基础.  相似文献   
175.
目的探索足部远端软组织缺损修复的较佳方法。方法采用足底深支或(和)第1跖背动脉逆行足背岛状皮瓣对6例足部远端软组织缺损创面进行修复。结果6例患者均一次性修复,软组织缺损最大面积8cm×6cm,术后随访1~4年,足部功能与外观均较满意。结论足底深支或(和)第1跖背动脉逆行足背岛状皮瓣血管解剖比较恒定,操作简单,是修复足远端软组织缺损的较好方法。  相似文献   
176.
脂肪抽吸术对胰岛素敏感性及脂质代谢的影响   总被引:2,自引:1,他引:1  
目的了解脂肪抽吸术对胰岛素抵抗与脂质代谢的影响,并探讨其临床意义。方法对20例接受腹部脂肪抽吸术者术前及术后2个月的血清三酰甘油、总胆固醇、高密度脂蛋白胆固醇、低密度脂蛋白胆固醇,胰岛素敏感性进行测量并进行比较。结果术后与脂肪抽吸术前比较,术后胰岛素敏感性增强(P〈0.01),血清总胆固醇与低密度脂蛋白胆固醇水平下降。结论腹部脂肪抽吸术在去除大量皮下脂肪的同时,对胰岛素抵抗、脂质代谢等心脑血管危险因素也有非常有益的影响。  相似文献   
177.
目的联合应用经腹腹膜前腹腔镜疝修补术(transabdominal preperitoneal prosthetic,TAPP)和腹腔内网片植入术(intraperitoneal onlay mesh,IPOM),探讨理想的腹腔镜下腹股沟疝修补的方法。方法2006年1月~12月,对30例成人腹股沟疝行腹腔镜下修补。以腹壁下血管内侧缘为界,把疝薄弱区纵行分成内侧和外侧,内侧采用改进的TAPP方法,外侧仍用IPOM方法。沿腹壁下血管内侧缘纵行剪开腹膜后向内侧游离的区域内基本上是无血管区,亦无重要的神经,组织疏松极易游离,数分钟内即可分离出所需要的面积(7.5 cm×6.5 cm)。补片的材料亦分为内侧和外侧,内侧是聚丙烯材料,外侧应用Proceed补片。结果30例均在硬膜外麻醉下完成,手术时间单侧30~40 min,平均35 min,双侧50~60 min,平均55min,术中出血1~5 ml,术后第2天可离床活动,术后3~4天出院,术后2周均恢复工作。术后随访2~12个月,平均9个月,无粘连性肠梗阻,腹股沟部和全身无不良反应。结论联合应用TAPP和IPOM后,能体现微创的原则,易掌握,损伤少,手术时间短,恢复快,手术效果确切。  相似文献   
178.
目的探讨急性高血压性脑出血患者细胞间粘附分子-1(ICAM-1)在血肿周围脑组织和正常脑组织中的表达及其意义。方法选择30例行开颅手术治疗的急性高血压性脑出血患者,采用免疫组化技术检测ICAM-1在血肿周围脑组织及正常脑组织中的表达。结果实验组血肿周围脑组织可见ICAM-1的表达水平上调,其表达水平明显高于正常脑组织的表达水平(P<0.01)。神经元和血管内皮细胞共同表达ICAM-1,且神经元表达较明显。结论ICAM-1在人类高血压性脑出血血肿周围脑组织的表达水平上调,其表达上调可能参与了血肿周围脑组织的白细胞浸润,最终引发炎性反应和继发性脑损伤。  相似文献   
179.
BACKGROUND: As a non-invasive technique which can provide comprehensive biological information, 1H-magnetic resonance spectroscopy (1H-MRS) may provide valuable reference data for irreversible recovery or reversible changes in ischemic tissue after stroke. OBJECTIVE: To monitor and evaluate the effect of the urokinase thrombolytic therapy after experimental acute cerebral ischemia by 1H-MRS technology and investigate its adaptability. DESIGN: Randomly controlled animal study. SETTINGS: Shenzhen Hospital of Peking University and National Key Laboratory of Pattern and Atom & Molecular Physics, Wuhan Physics and Mathematics Institute, Chinese Academy of Science. MATERIALS: Eleven healthy adult Sprague-Dawley (SD) rats, weighing 260–300 g and of both genders, were supplied by Experimental Animal Center of Tongji Medical Collage, Huazhong University of Science and Technology [SCXK (e) 2004-007]. 4.7T superconducting nuclear magnetic resonance meter was provided by Brucker Company. METHODS: The experiment was carried out in Shenzhen Hospital of Peking University and National Key Laboratory of Pattern and Atom & Molecular Physics, Wuhan Physics and Mathematics Institute, Chinese Academy of Science from August 2003 to December 2005. ① The rats were randomly divided into 30-minute self-thrombo-embolism group (n =6) and 60-minute self-thrombo-embolism group (n =5). Six rats in 30-minute self-thrombo-embolism group were occluded with clot embolus for 30 minutes and 5 rats in 60-minute self-thrombo-embolism group were occluded for 60 minutes. 10 000 U/kg urokinase was dissolved in 2 mL saline and the operation lasted for 5 minutes. ② 1H-MRS was performed before thrombolysis and at 3 hours and 24 hours after successful embolization. The metabolic changes of N-acetyl-L-aspartic acid (NAA)/phosphocreatine (PCr) + creatine (Cr), choline phosphate (Cho)/PCr+Cr and lactic acid (Lac)/PCr+Cr in the region of interests were analyzed. ③ The T2W image was conducted 24 hours after the thrombolytic therapy with TR=500 ms and TE=25 ms. ④ The subjects were sacrificed immediately after 1H-MRS and the brain tissues were cut into pieces and stained with HE method; in addition, pathological changes were observed under optic microscope. MAIN OUTCOME MEASURES: ① Metabolic changes of NAA/PCr+Cr, Cho/PCr+Cr and Lac/PCr+Cr in the region of interests; ② T2W image at 24 hours after the thrombolysis; ③ pathological observation of brain tissue. RESULTS: Eleven rats were all involved in the final analysis. ① Metabolic changes in the region of interests : In 30-minute self-thrombo-embolism group, the Lac peak emerged immediately after the embolism, but the ischemic zone decreased 3 hours after the thrombolytic therapy (0.252±0.01, 0.603±0.01, P < 0.01). Lac/(PCr+Cr) ratio was 0.290±0.01 at 24 hours after thrombolysis, which was higher than that at 3 hours after thrombolysis (P < 0.01). The NAA/ (PCr+Cr) ratio decreased significantly at 3 hours after the thrombolysis as compared with that before thrombolysis (0.922±0.16, 1.196±0.01, P < 0.05). In 60-minute self-thrombo-embolism group, the Lac/(PCr+Cr) ratio was higher at 3 hours after thrombolysis than that before thrombolysis (0.846±0.12, 0.601±0.11, P < 0.05) and the NAA/(PCr+Cr) decreased at 3 hours after the embolism. Fluctuation of NAA/ (PCr+Cr) ranged from 0.68 to 0.75 before thrombolysis and from 0.71 to 0.75 at 3 hours after thrombolysis. ② T2W image: T2W image showed that 2 subjects in 30-minute self-thrombo-embolism group whose Lac/NAA was higher than 0.7 suffered from intracranial hemorrhage. This meant that the subjects with Lac/NAA > 0.7 were more likely to suffer from intracranial hemorrhage. ③ Histological and morphological examinations: Optic microscope demonstrated that interspace surrounding nerve cells was widened at ischemic center; neurons were swelling; nucleus was stained lightly; pyknosis and mesenchymal edema were mainly observed in lateral cortex of brow and vertex and in lateral part of corpus striatum. CONCLUSION: ①Compound parameters in ischemic area before thrombolysis should be regarded as an important predicting marker for thrombolytic therapy, effect evaluation and termination. ② 1H-MRS combining with other imaging technique is a detecting way for screening cases who are suitable for thrombolytic therapy.  相似文献   
180.
Th1/Th2炎症极化与肺气肿和肺纤维化   总被引:3,自引:1,他引:2  
肺气肿具有Ⅰ型T辅助细胞(Th1)炎症极化的特征,表现为损伤过度和修复不足,肺实质的破坏增加,肺间质变薄。与之相反,肺纤维则具有Ⅱ型T辅助细胞(Th2)炎症极化,表现为损伤后修复过度,肺间质增厚,胶原沉积。通过调控Th1和Th2的炎症趋势来控制肺组织的损伤和修复的结局可能会为肺气肿和肺纤维化的防治提供新思路。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号