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   397344篇
  免费   24767篇
  国内免费   2842篇
耳鼻咽喉   5376篇
儿科学   8761篇
妇产科学   10507篇
基础医学   56856篇
口腔科学   11915篇
临床医学   31541篇
内科学   81442篇
皮肤病学   9019篇
神经病学   28757篇
特种医学   15120篇
外国民族医学   85篇
外科学   62728篇
综合类   10034篇
现状与发展   1篇
一般理论   66篇
预防医学   18561篇
眼科学   9861篇
药学   32160篇
  1篇
中国医学   2230篇
肿瘤学   29932篇
  2021年   2832篇
  2019年   2946篇
  2018年   4948篇
  2017年   3704篇
  2016年   3929篇
  2015年   4505篇
  2014年   6168篇
  2013年   7938篇
  2012年   11010篇
  2011年   11196篇
  2010年   6684篇
  2009年   6309篇
  2008年   10274篇
  2007年   11180篇
  2006年   11017篇
  2005年   10127篇
  2004年   9540篇
  2003年   9243篇
  2002年   8801篇
  2001年   28444篇
  2000年   28989篇
  1999年   23826篇
  1998年   5266篇
  1997年   4317篇
  1996年   3887篇
  1995年   3524篇
  1994年   3156篇
  1993年   2925篇
  1992年   16150篇
  1991年   14908篇
  1990年   14273篇
  1989年   14096篇
  1988年   12706篇
  1987年   12174篇
  1986年   11221篇
  1985年   10430篇
  1984年   7007篇
  1983年   5670篇
  1982年   2783篇
  1979年   5546篇
  1978年   3428篇
  1977年   3061篇
  1975年   2724篇
  1974年   3131篇
  1973年   2949篇
  1972年   2912篇
  1971年   2850篇
  1970年   2583篇
  1969年   2628篇
  1968年   2328篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
942.
943.
Polyglucosan bodies (PGB) in the central nervous system of an old male fox, Vulpes vulpes japonica, without neurological signs were examined by light and electron microscopy, lectin histochemistry and immunohistochemistry. Fox PGB were round, slightly-basophilic and PAS-positive structures. Most of the bodies were situated free in the neuropil. Electron microscopically, fox PGB were composed mainly of branching filaments and electron-dense material. Lectin histochemistry revealed that fox PGB contained mannose and galactose in addition to glucose. Fox PGB were immunoreactive for monoclonal antibodies raised against human polyglucosan. These findings indicate that fox PGB are similar to feline ones.  相似文献   
944.
Summary Fifty-five patients with metastatic non-small cell lung cancer (NSCLC) were entered into this phase II randomized study for evaluating three new agents: gallium nitrate, amonafide and teniposide. The patients had to have ECOG performance status 0 or 1, no prior chemotherapy, and adequate hematological, hepatic and renal functions. Forty-seven patients were eligible and evaluable. Fourteen were randomized to receive gallium nitrate, 18 to amonafide and 15 to teniposide. Seventy-four percent of eligible patients were male. The majority of patients (89%) had an ECOG performance status 1. ECOG grade 4 toxicity occurred twice in patients on gallium nitrate, seven times on amonafide and 18 times on teniposide. The cause of death was attributed to amonafide in one patient (from sepsis) and to teniposide in two patients (due to infection and leukopenia). There was no objective response in all the patients entered. The overall survival times ranged from 2 weeks to 156 weeks with a median of 23 weeks. There were no survival differences among the three treatment arms. We conclude that gallium nitrate, amonafide and teniposide are inactive in metastatic NSCLC and do not warrant any further testing in this disease.The contents of this study is solely the responsibility of the authors and does not necessarily represent the official views of the National Cancer Institute.  相似文献   
945.
In the present paper fifty patients with symptoms of inner ear dysfunction, primarily deafness, vertigo or both, were subjected to a detailed history, pure tone audiometry and caloric tests. A detailed serum lipid analysis was done of all the patients. It was concluded that atherosclerotic disease of the labyrinthine vessels usually affects patients above forty years of age. It occurs bilaterally. Commonly both the cochlear and vestibular components are involved. Raised serum total cholesterol, L.D.L. cholesterol levels and hypertension, are more contributory as risk factors in its development.  相似文献   
946.
A technique for estimation of the longitudinal relaxation time of a large homogeneous object with an acquisition time of 4 s or less was developed by combining spatially selective rf tagging pulses with a T1-weighted magnetization-prepared gradient-echo sequence. Multiple 5-mm-wide tagged areas are laid orthogonal to the imaging section of interest. The contrast between each tag and the untagged regions differs because each tag is produced at a different time. The T1 value is determined from the nulling time at which tagged and untagged areas have no contrast.  相似文献   
947.
948.
Metastatic calcifications according to histopathologic and scintigraphic findings have been well-defined. The authors report a postoperative case of hyperparathyroidism with multiple metastatic calcifications in the lung, kidney, stomach, heart, and vessels that were primarily detected by bone scintigraphy and demonstrated by CT. Tc-99m MDP bone scintigraphy showed a markedly increased accumulation of radioactivity diffusely throughout the lung, left ventricular wall, both kidneys, and the gastric cardia and body. In the lung, plain films showed almost normal lung. CT, however, demonstrated patchy, slightly increased densities in the lung bilaterally. Cardiac CT indicated a considerably increased density of the ventricular myocardium and remarkable calcification in or near the atrioventricular septum or annulus fibrosus. Upper abdominal CT demonstrated increased densities diffusely throughout the gastric mucosa and renal cortex. Only vascular calcifications were depicted by plain films. Using both bone scintigraphy and CT provides accurate information about each lesion and each tissue, allowing precise diagnosis of even a questionable lesion in the early stage of metastatic calcification. Early diagnosis and early therapy offer the best chance for cure or palliative therapy.  相似文献   
949.
950.
Repeat hepatic resections for metastatic colorectal cancer.   总被引:7,自引:0,他引:7       下载免费PDF全文
OBJECTIVE: The authors weighed the risks and benefits of repeat liver resections for colorectal metastatic disease. METHOD: In the 6-year period between January 1985 and June 1991, 499 patients underwent liver resections for colorectal metastases at the Memorial Sloan-Kettering Cancer Center. Of these, 25 patients had repeat surgical resections for isolated recurrent disease to the liver. The clinical data for these patients were reviewed. RESULTS: The median interval between the two resections was 11 months. There were no perioperative deaths, and the complication rate was 28%. Median follow-up after the second liver resection is 19 months, with median survival of 17 months for nonsurvivors. Although the median survival after the second resection is 30 months, 20 of the 25 patients have had recurrences with a median disease-free interval of only 9 months. No characteristic of primary or metastatic disease predicted outcome, including time between presentation of the primary and development of liver metastases, disease-free interval after the first liver resection, and bilobar liver involvement. CONCLUSIONS: Although repeat liver resections can be performed safely and improves survival, the likelihood of cure from such resection therapy is low. This likelihood of further recurrences encourage studies of adjuvant or alternative treatments of this population.  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