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   26628篇
  免费   2113篇
  国内免费   2382篇
耳鼻咽喉   68篇
儿科学   358篇
妇产科学   592篇
基础医学   1415篇
口腔科学   325篇
临床医学   2870篇
内科学   7347篇
皮肤病学   68篇
神经病学   211篇
特种医学   737篇
外国民族医学   1篇
外科学   4051篇
综合类   4460篇
预防医学   1234篇
眼科学   19篇
药学   2418篇
  33篇
中国医学   1078篇
肿瘤学   3838篇
  2024年   40篇
  2023年   430篇
  2022年   866篇
  2021年   1124篇
  2020年   1025篇
  2019年   901篇
  2018年   825篇
  2017年   814篇
  2016年   950篇
  2015年   1058篇
  2014年   2107篇
  2013年   2025篇
  2012年   1816篇
  2011年   1793篇
  2010年   1509篇
  2009年   1457篇
  2008年   1515篇
  2007年   1521篇
  2006年   1407篇
  2005年   1229篇
  2004年   850篇
  2003年   723篇
  2002年   644篇
  2001年   598篇
  2000年   547篇
  1999年   438篇
  1998年   335篇
  1997年   348篇
  1996年   322篇
  1995年   251篇
  1994年   225篇
  1993年   174篇
  1992年   144篇
  1991年   140篇
  1990年   124篇
  1989年   108篇
  1988年   85篇
  1987年   65篇
  1986年   56篇
  1985年   75篇
  1984年   56篇
  1983年   41篇
  1982年   59篇
  1981年   40篇
  1980年   59篇
  1979年   51篇
  1978年   40篇
  1977年   34篇
  1976年   27篇
  1975年   12篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Background: The gastric bypass operation has evolved since 1966 when it was first introduced. The purpose of this study was to determine the present state of gastric bypass by consensus among the members of the American Society for Bariatric Surgery (ASBS). Method: A questionnaire was sent to all members of the ASBS. Forty-three percent responded reporting over 41,200 cases. Results: Results were analyzed by using χ2 tests with a null hypothesis. Surgeons agreed on several technical aspects, preferring a vertical to a horizontal stapleline; estimating, rather than measuring, the pouch volume at an average of 22 cc. Few surgeons divide the short gastric vessels, and only 25% of surgeons polled use a restrictive ring or band proximal to the gastroenterostomy. Most surgeons calibrate the gastroenterostomy, reporting a preferred average diameter of 12.3 cm. There was no consensus regarding forming the gastroenterostomy, 58% preferring hand-sewn and 42% stapled anastomoses. There was no consensus regarding dividing the gastric pouch from the bypassed stomach: Conclusion: The preferred gastric bypass is vertical, with the pouch estimated at 20-25 cc, and the gastroenterostomy calibrated at 12 mm diameter. The short gastric vessels need not be divided, and restrictive bands or rings are not preferred. This technique of gastric bypass should be used as the control procedure when modifications are tested in future trials. Randomized prospective studies are suggested to probe the benefits of division of the stomach pouch from the bypassed stomach.  相似文献   
92.
Objective: To determine the contribution of several variables to fluid loss during transcervical resection of submucous myomas.Design: An observational study using multiple linear regression analyses.Setting: A university-affiliated training hospital and a university department of clinical epidemiology and biostatistics.Patient(s): Patients with submucous myomas.Intervention(s): Transcervical resection of submucous myomas and monitoring of fluid loss.Main Outcome Measure(s): Patient age, uterine enlargement, treatment with GnRH analogues or 8-ornithine-vasopressin, type of anesthesia, number of myomas, intramural extension of the myoma (type of myoma), and operating time were tested as variables.Result(s): Only intramural extension of the myoma and operating time were obviously related to fluid loss. For the other variables, such a relation was weak at best. The relation between fluid loss and operating time was not modified by any of the other variables.Conclusion(s): Because fluid loss is an important limiting factor in the transcervical resection of submucous myomas, special attention should be paid to reduction of the operating time and preoperative assessment of the intramural extension of the myoma to guide appropriate patient selection.  相似文献   
93.
胃癌组织COX-2的表达及其与细胞增殖和凋亡的关系   总被引:8,自引:1,他引:7  
目的 :探讨环氧化酶 - 2 (cyclooxygenase - 2 ,COX - 2 )在胃癌组织中的表达与癌细胞增殖和凋亡的关系。 方法 :采用免疫组织化学的方法检测 4 3例胃癌患者COX - 2和增殖细胞核抗原 (PCNA)的表达 ,用TUNEL法检测原位细胞凋亡的情况。分别计算细胞增殖指数 (MI)和凋亡指数 (AI)。结果 :胃癌组织COX - 2表达的阳性率为 6 0 .4 7% ,明显高于对照组 (P <0 .0 1)。COX - 2的高表达与胃癌淋巴结的转移和临床分期有关 ,与肿瘤大小、浸润深度、分化程度均无关。COX - 2阳性胃癌组中MI高于COX - 2阴性胃癌组 ,而AI却低于COX - 2阴性胃癌组 (P均 <0 .0 1)。结论 :COX - 2的过度表达可促进胃癌细胞增殖、抑制细胞凋亡 ,在胃癌的发生、发展过程中起着重要的作用。  相似文献   
94.
Laparoscopically assisted gastric surgery using Dexterity Pneumo Sleeve   总被引:1,自引:0,他引:1  
Background: Laparoscopic surgery has been successfully applied to several gastrointestinal procedures. Although the totally laparoscopic gastrectomy is feasible, tactile sensation and manipulation of the organ as well as the lesion are decreased when compared to open surgery. The Dexterity Pneumo Sleeve is a new device which allows the surgeon to insert a hand into the abdominal cavity while preserving the pneumoperitoneum. This device was used for patients who underwent laparoscopic gastric surgery. Methods: The first patient presented with a non-Hodgkin's lymphoma of the stomach. A laparoscopically assisted distal gastrectomy was performed with Roux-en-Y reconstruction. The second patient had a 5-cm leiomyoma involving the greater curve of the stomach, and this device was used for manipulation of the tumor. The last patient suffered from morbid obesity with its associated medical complications and a ventral hernia. The Sleeve was applied at the hernia site and a laparoscopically assisted gastric bypass was performed. Results: The Pneumo Sleeve was useful in these cases for tactile localization of the tumor and for retraction and manipulation of the stomach and surrounding upper abdominal organs. Conclusions: The utilization of this device resulted in a more easily performed dissection, resection, and anastomosis and was felt to decrease operation time. Received: 18 September 1996/Accepted: 26 December 1996  相似文献   
95.
Background: Morbid obesity is a serious disease that afflicts over five million Americans, threatening their health with such co-morbidities as diabetes, arthritis, pulmonary failure and stroke. Surgery is the only effective therapy, providing long-term control of weight, diabetes, pulmonary failure, and hypertension for as long as 14 years. Because the operation presents a major expense, this study examined whether X-ray examination of the gut could be omitted safely as a cost-saving measure. Methods: The records of 814 consecutive morbidly obese patients who underwent gastric bypass were reviewed to determine: (1) whether these individuals had undergone an upper gastro-intestinal (GI) series, and (2) if these studies influenced therapy or caused cancellation or postponement of surgery. Results: Of the 814 patients, 657 (80.7%) underwent a preoperative GI radiography. Of these examinations, 393 (59.8%) were normal, with the following abnormalities in the remaining 264: hiatal hernia, 164; esophageal reflux, 39; Schatzki's ring, 18; small bowel diverticula, four; renal stones, four; malrotation, three; gall stones, two; pyloric ulcer, one; possible pelvic mass, one; calcified leiomyoma, one; and dysphagial lusoria, one. None of these findings resulted in cancellation or a delay in surgery. Conclusions: The upper GI series can be safely omitted from the routine preoperative evaluation of patients undergoing gastric bypass. At a cost of $741.00 per examination, this change represents significant potential savings. Similar evaluations of other routine preoperative tests may well provide a better basis for the evaluation of these complex patients.  相似文献   
96.
目的 探讨环氧化酶2(COX-2)基因启动子区甲基化水平和蛋白表达与胃黏膜病变的关系,并对其相关的影响因素进行研究.方法 以1201例患有不同胃黏膜病变的高危人群为研究对象,采用免疫组织化学方法榆测COX-2表达,用亚硫酸氢钠-变性高效液相色谱(DHPLC)对COX-2启动子甲基化率进行定量分析,采用13C尿素呼气实验(13C-UBT)对幽门螺旋杆菌(H priori)感染状况进行测定.结果 COX-2甲基化率中位数随胃黏膜病变的加重逐渐升高,在浅表性胃炎和慢性萎缩性胃炎(SG/CAG)、肠上皮化生(IM)及不确定性异型增生和异璎增生(Ind DYS/DYS)病变中分别为10.6%、11.8%、13.8%,各病变组之间差异有统计学意义(X2=8.312,P=0.016).分层分析显示,在H pylori感染阴性病例中,COX-2甲基化率仍随病变加重明显升高,在SG/CAG、IM、Ind DYS/DYS病变中其中位数分别为8.8%、10.6%、14.1%(X2=6.629,P=0.036).进一步分析发现,COX-2甲基化率随着COX-2表达强度的增强而降低,由COX-2弱阳性表达的13.3%降至强阳性表达的7.6%(X2=10.400,P=0.015).结论 COX-2启动子甲基化水平与胃黏膜病变程度及H pylori感染状况密切相关,并与COX-2表达强度呈负相关,说明COX-2启动子区异常甲基化可能在胃黏膜病变的演变过程中起重要作用.  相似文献   
97.
理气类中药对大鼠离体胃平滑肌条的作用   总被引:9,自引:0,他引:9  
目的:观察理气类中药对大鼠离体胃平滑肌条运动的影响。方法:将肌条放置在灌流肌槽中,用生理记录仪记录肌条的收缩活动。结果:陈皮、枳实对胃各部位平滑肌条均为抑制效应,香附、薤白、木香、柿蒂、乌药对胃底肌条为兴奋效应,但对其他部位肌条则表现为兴奋或抑制不同的效应,沉香仅降低胃窦环行肌收缩波平均振幅,对其他肌条无影响。结论:理气类中药对大鼠离体胃平滑肌条既有兴奋作用,也有抑制作用。  相似文献   
98.
[目的 ]探讨前置胎盘分娩方式的选择及分娩过程中减少出血的方法。 [方法 ]对 2 6例前置胎盘病例的发病率、诊断方法、胎盘分型、分娩方式、出血情况及剖宫产术子宫切口方式与出血的关系几个方面进行回顾性分析。[结果 ]2 6例中手术率为 96 .1 5 % ,阴道分娩率为 3.85 % ,1例阴道分娩出血量为 6 0 0mL ,剖宫产术平均出血量为 6 74 .5 5mL ;剖宫产术中切口方式选择推开胎盘与避开胎盘出血量比较 ,差异无显著性 (P >0 .0 5 ) ,切开胎盘与推开胎盘出血量比较及切开胎盘与避开胎盘的出血量比较 ,差异均有显著性 (P均 <0 .0 1 )。[结论 ]剖宫产术可成为前置胎盘终止妊娠的主要方法 ,同时原则上应避开胎盘选择切口  相似文献   
99.
Background: For patients with incurable malignant gastric outlet obstruction and cholestasis, laparoscopic gastrojejunostomy combined with endoscopic biliary stent placement seems to offer a minimally invasive palliation. Methods: We retrospectively analyzed the data of 16 patients submitted to laparoscopic gastrojejunostomy. Laparoscopic gastroenterostomy was performed as an antecolic, side-to-side gastrojejunostomy with enteroenterostomy. In 12 patients cholestasis was relieved preoperatively by stent placement via endoscopy (n= 6, 37.5%), percutaneous access (n= 5, 31%) or bilioenteric anastomosis (n= 1, 6.25%). One patient needed a percutaneous Yamakawa prosthesis postoperatively. Results: Mean operative time was 126 min. There were no intraoperative complications. In one patient conversion to open surgery became necessary because of extensive adhesions. The only postoperative complication was bleeding from a trocar site requiring reintervention; there was no mortality. Median postoperative hospital stay was 7 days. Delayed gastric emptying was observed in 3 (18.7%) patients. Median survival was 87 days after the operation. All patients died from their primary disease but could maintain oral intake during the remaining survival time. Conclusions: We conclude that laparoscopic gastrojejunostomy and endoscopic or percutaneous biliary stenting provide a good functional result while impairing the quality of life only to a minimal extent. Received: 7 May 1996/Accepted: 12 December 1996  相似文献   
100.
王凤军 《河北医学》2003,9(11):984-986
目的 :研究胃癌第一站淋巴结窦组织细胞增生 (SH)、生发中心增生 (GCH)对胃癌第一站淋巴结转移及预后的影响。方法 :将SH、GCH分别分为 - ,+ ,+ +三级 ,分析SH ,GCH对胃癌第一淋巴结转移的影响 ,比较其 5年生存率。结果 :①SH -患者淋巴结转移率明显比SH + ,SH + +高 (P <0 .0 0 5 ) ;5年生存率随SH分级数升高而升高 (P <0 .0 0 5 ) ;②GCH -患者淋巴结转移率明显比GCH + ,GCH+ +高 (P <0 .0 0 5 ) ;5年生存率随GCH分级数升高而升高 (P <0 .0 1)。结论 :SH ,GCH患者胃癌第一站淋巴结转移率较低 ;SH ,GCH分级数越高预后越好 ;SH ,GCH可作为预测胃癌预后的指标之一。  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