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   18254篇
  免费   2007篇
  国内免费   92篇
耳鼻咽喉   144篇
儿科学   570篇
妇产科学   300篇
基础医学   2539篇
口腔科学   612篇
临床医学   1883篇
内科学   3479篇
皮肤病学   189篇
神经病学   2125篇
特种医学   716篇
外科学   2558篇
综合类   472篇
一般理论   30篇
预防医学   1850篇
眼科学   481篇
药学   1259篇
  1篇
中国医学   38篇
肿瘤学   1107篇
  2021年   222篇
  2020年   163篇
  2019年   271篇
  2018年   267篇
  2017年   246篇
  2016年   278篇
  2015年   298篇
  2014年   455篇
  2013年   651篇
  2012年   893篇
  2011年   1053篇
  2010年   568篇
  2009年   502篇
  2008年   886篇
  2007年   906篇
  2006年   882篇
  2005年   886篇
  2004年   822篇
  2003年   835篇
  2002年   819篇
  2001年   565篇
  2000年   617篇
  1999年   504篇
  1998年   287篇
  1997年   275篇
  1996年   262篇
  1995年   208篇
  1994年   187篇
  1993年   199篇
  1992年   364篇
  1991年   327篇
  1990年   354篇
  1989年   297篇
  1988年   337篇
  1987年   279篇
  1986年   260篇
  1985年   254篇
  1984年   206篇
  1983年   188篇
  1982年   158篇
  1981年   160篇
  1980年   150篇
  1979年   193篇
  1978年   143篇
  1977年   127篇
  1976年   120篇
  1975年   94篇
  1974年   126篇
  1973年   118篇
  1972年   99篇
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
101.
A successful experimental treatment for gram-positive sepsis to our knowledge has not been achieved. The objectives of this study were to develop a nonhuman primate model of lethal gram-positive sepsis employing the micro-organism Staphylococcus aureus and to determine the efficacy of treatment using monoclonal antibody (MAb) to tumor necrosis factor alpha (TNF). The antibody was administered intravenously, 15 mg/kg, 30 minutes after the beginning of a 2-hour infusion of S. aureus, 4 x 10(10) colony forming units/kilogram. The baboons infused with S. aureus demonstrated the release of the cytokines TNF and interleukin-6 (IL-6), but endotoxin was not observed in the plasma at any time. Treatment with antibody to TNF abolished the rise in serum TNF levels and reduced the increased levels of IL-6. Treatment with MAb to TNF prevented multiple organ failure and achieved permanent (> 7 day) survival of all baboons.  相似文献   
102.
103.
104.
Frame-based stereotactic body radiation therapy (SBRT), such as that conducted with Elekta's Stereotactic Body Frame, can provide an extra measure of precision in the delivery of radiation to extracranial targets, and facilitates secure patient immobilization. In this paper, we review the steps involved in optimal use of an extra-cranial immobilization device for SBRT treatments. Our approach to using frame-based SBRT consists of 4 steps: patient immobilization, tumor and organ motion control, treatment/planning correlation, and daily targeting with pretreatment quality assurance. Patient immobilization was achieved with the Vac-Loc bag, which uses styrofoam beads to conform to the patient's shape comfortably within the body frame. Organ and motion control was assessed under fluoroscopy and controlled via a frame-mounted abdominal pressure plate. The compression screw was tightened until the diaphragmatic excursion range was < 1 cm. Treatment planning was performed using the Philips Pinnacle 6.2b system. In this treatment process, a 20 to 30 noncoplanar beam arrangement was initially selected and an inverse beam weight optimization algorithm was applied. Those beams with low beam weights were removed, leaving a manageable number of beams for treatment delivery. After planning, daily targeting using computed tomography (CT) to verify x-, y-, and z-coordinates of the treatment isocenter were used as a measure of quality assurance. We found our daily setup variation typically averaged < 5 mm in all directions, which is comparable to other published studies on Stereotactic Body Frame. Treatment time ranged from 30 to 45 minutes. Results demonstrate that patients have experienced high rates of local control with acceptable rates of severe side effects - by virtue of the tightly constrained treatment fields. The body frame facilitated comfortable patient positioning and quality assurance checks of the tumor, in relation to another set of independent set of coordinates defined by the body frame fiducials. The ability to impose abdominal compression proved to be a simple way to reduce target and tissue motion. SBRT with Stereotactic Body Frame enables comfortable patient immobilization and facilitates repeated registering and re-registering of the patient to the frame. With the body frame, large-dose-per fraction treatment is possible for localized tumor deposits with the aim of attaining a more therapeutic result.  相似文献   
105.
106.
107.
108.
109.
Early-stage colorectal cancer is potentially curable. In the present study, we applied quantitative fluorescence image analysis (QFIA) cytology to the detection of experimental colorectal cancer in a rodent model. QFIA cytology combines visual cytologic examination with quantitation of DNA content in single exfoliated cells. Cancer was induced by treating 110 rats with subcutaneous 1,2-dimethylhydrazine. Sequential colon washes were obtained weekly from each animal for 20 weeks. Control animals were treated identically except for the administration of carcinogen. Cells that were cytologically abnormal or had increased DNA content were found starting in the second week. By the eighth week, roughly 50 percent of animals had positive results, and this level remained approximately constant for the duration of the study. Tissue pathologic results were normal during weeks 1 to 7. Dysplasias became common during weeks 8 to 15 whereas most cancers appeared during weeks 16 to 21. These results indicate that QFIA cytology is a highly sensitive method for detecting even preneoplastic changes resulting from carcinogen administration and may prove useful in detecting human colorectal cancer.  相似文献   
110.
From June 1978 to December 1987, 106 revision total hip arthroplasties (THA) for acetabular salvage were performed using a bipolar device. Bone grafting was necessary in most of the patients. Five patients were unavailable for follow-up examination, leaving 96 patients (101 hips), who were followed for an average of two years 11 months (range, two months to 8.5 years). Excellent or good results were obtained in 43 patients; fair results were achieved in 20 patients. Of the nine patients with poor results, five demonstrated roentgenographic evidence of subluxation, and four showed no roentgenographic changes that could explain their persistent pain. Twenty-nine of these bipolar revisions failed and required reoperation. Fourteen of these failures were revised using fixed, cementless devices in conjunction with bone grafting. Ten patients developed deep-wound infection. Nine were treated successfully; the tenth patient died of overwhelming sepsis, her case complicated by multiple infected joint arthroplasties. While the results of revision THA in the present series are not as satisfactory as those reported by others who used fixed cemented or fixed cementless acetabular components, they are superior to the results obtained with excisional arthroplasty, the only alternative in many of these cases.  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