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   23642篇
  免费   1694篇
  国内免费   68篇
耳鼻咽喉   251篇
儿科学   938篇
妇产科学   604篇
基础医学   3135篇
口腔科学   678篇
临床医学   2669篇
内科学   4682篇
皮肤病学   413篇
神经病学   1838篇
特种医学   1078篇
外科学   3177篇
综合类   403篇
一般理论   43篇
预防医学   2206篇
眼科学   348篇
药学   1426篇
  1篇
中国医学   19篇
肿瘤学   1495篇
  2021年   333篇
  2020年   232篇
  2019年   370篇
  2018年   402篇
  2017年   338篇
  2016年   346篇
  2015年   438篇
  2014年   598篇
  2013年   823篇
  2012年   1125篇
  2011年   1218篇
  2010年   690篇
  2009年   600篇
  2008年   1095篇
  2007年   1198篇
  2006年   1115篇
  2005年   1109篇
  2004年   963篇
  2003年   951篇
  2002年   829篇
  2001年   654篇
  2000年   637篇
  1999年   537篇
  1998年   317篇
  1997年   272篇
  1996年   279篇
  1995年   263篇
  1994年   256篇
  1993年   223篇
  1992年   482篇
  1991年   469篇
  1990年   454篇
  1989年   470篇
  1988年   436篇
  1987年   385篇
  1986年   329篇
  1985年   395篇
  1984年   309篇
  1983年   272篇
  1982年   180篇
  1981年   145篇
  1979年   228篇
  1978年   196篇
  1977年   166篇
  1976年   162篇
  1975年   169篇
  1974年   164篇
  1973年   211篇
  1972年   168篇
  1971年   149篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Thirty-five abdominal computed tomographic (CT) scans of 27 patients with peritoneal metastases from a mucin-producing tumor of the appendix, colon, small bowel, or ovary were retrospectively reviewed. Fifteen scans were obtained of 15 patients after CT with intraperitoneal infusion of contrast material (IP), and 20 scans were obtained of 16 patients with CT without IP. Subsequent exploratory laparotomy revealed that all 27 patients had multi-focal spread of peritoneal metastases. The sensitivity of CTIP and CT without IP for detection of peritoneal metastases at all sites of involvement was 61% and 59%, respectively. For CTIP, the highest sensitivity was in the right subphrenic space (88%), splenic hilum (86%), and left subphrenic space (83%). For CT without IP, the highest sensitivity was noted in the splenic hilum (100%), left subphrenic space (75%), and left paracolic gutter (75%). CTIP and CT without IP had low sensitivity for detection of disease in the greater omentum (50% each) and small-bowel mesentery (38% and 59%, respectively), two areas that had the highest frequency of metastases.  相似文献   
22.
23.
BACKGROUND: Bowel-associated dermatosis-arthritis syndrome denotes the occurrence of diarrhoea with arthritis and skin lesions related to bowel disease with or without bowel bypass. In this condition, the histological finding of cutaneous aseptic neutrophilic cell infiltrate is non-specific and common to a wide spectrum of neutrophilic dermatoses, including pyoderma gangrenosum. OBSERVATION: We describe a 78-year-old woman with fever, abdominal discomfort and arthralgias, who developed grouped pustular lesions on her shins with histologically spongiform pustule formation. Aetiological assessment disclosed diverticular disease with sigmoid stenosis. CONCLUSION: Although clinical and histological features in our case fit the diagnosis of bowel-associated dermatosis-arthritis syndrome, they may also correspond to a pustular variant of pyoderma gangrenosum. Our observation raises the question of the nosological classification of bowel-associated dermatosis-arthritis syndrome within the spectrum of neutrophilic diseases.  相似文献   
24.
Except for two reported patients, increased free sialic acid excretion has been associated with lysosomal storage. This is a report of a child with progressive neurologic deterioration and increased excretion of free sialic acid. Although lysosomal storage was absent, nuclear invagination or inclusions were present.  相似文献   
25.
Exposure of ZR-75-1 human breast cancer cells for 48 h to human recombinant interferon alpha (IFN alpha) resulted in increased expression of oestrogen receptors as measured in a whole cell binding assay. This effect was inversely proportional to dose being significant following treatment with 10-100 IU IFN ml-1 and was only observed at a low initial cell plating density. The extent of the increase in oestrogen receptor levels ranged from 1.2- to 7.2-fold following treatment with 10 IU IFN ml-1. No increase in progesterone receptor expression was observed under the same experimental conditions. Concentrations of IFN which increased oestrogen receptor levels had no effect on cell proliferation. IFN (500 IU ml-1) inhibited cell proliferation and the combination of this treatment with tamoxifen (2 microM) had a greater anti-proliferative effect than either drug alone although there was no evidence of synergism. However, a 5-day pretreatment of cells with IFN (10 IU ml-1) markedly sensitised them to the growth-inhibiting effect of a subsequent 6-day exposure to tamoxifen.  相似文献   
26.
BACKGROUND: Neither the presence nor prevalence of enteric hyperoxaluria has been recognized after Roux-en-Y gastric bypass (RYGBP). We have noted a high rate of oxalate nephrolithiasis and even 2 patients with oxalate nephropathy in this patient population postoperatively. Our aim was to determine the frequency of the occurrence and effects of enteric hyperoxaluria after RYGBP. METHODS: Retrospective review of all patients at our institution diagnosed with calcium oxalate nephrolithiasis or oxalate nephropathy after standard (n = 14) or distal (n = 9) RYGBP. The mean postoperative follow-up was 55 months. RESULTS: A total of 23 patients (14 men and 9 women; mean age 45 years; mean preoperative body mass index 55 kg/m(2)) developed enteric hyperoxaluria after RYGBP, defined by the presence of oxalate nephropathy (n = 2) or calcium oxalate nephrolithiasis (n = 21) and increased 24-hour excretion of urinary oxalate and/or calcium oxalate supersaturation. Enteric hyperoxaluria was recognized after a mean weight loss of 46 kg at 29 months (range 2-85) after RYGBP. Two patients developed renal failure and required chronic hemodialysis. Of the 21 patients with nephrolithiasis, 14 had no history of nephrolithiasis preoperatively, and 19 of 21 required lithotripsy or other intervention. Of the 23 patients, 20 tested had increased oxalate excretion, and 14 of 15 tested had high urine calcium oxalate supersaturation. CONCLUSION: Enteric hyperoxaluria, nephrolithiasis, and oxalate nephropathy must be considered with the other risks of RYGBP. Efforts should be made to identify factors that predispose patients to developing hyperoxaluria.  相似文献   
27.
28.
29.
A 7-cm anterior mediastinal tumor in an 80-year-old woman was found by light and electron microscopy to be a neuroblastoma. Immunoreactivity for neuron-specific enolase, synaptophysin, and chromogranin supported the diagnosis. Neuroblastoma is an uncommon tumor in adults and we are not aware of a previous report of such a tumor in a patient of this age.  相似文献   
30.
Single breath-holding gradient echo techniques fast imaging with steady-state free precession (FISP) and fast low angle shot (FLASH) images were evaluated in the study of the abdomen in 16 patients (13 liver, two kidney, and one pancreas examinations). Gradient echo images were compared retrospectively with conventional spin echo images for image quality (depiction of pathology and representation of anatomic detail), and contrast characteristics were evaluated. All lesions were shown on gradient echo images, and in three of 16 cases gradient echo images were more diagnostic than spin echo images. On both FISP and FLASH images, most hepatic metastases were hyperintense relative to normal liver. The predicted flip angles for maximal contrast for the liver were modeled from signal intensity equations for FISP and FLASH and yielded predicted flip angles of approximately 40-55 degrees for FISP and 15-25 degrees for FLASH. Peak signal-to-noise ratio in liver of normal volunteers occurred at approximately 30 degrees for both FISP and FLASH. Single breath-holding gradient echo images are useful in the evaluation of abdominal structures and this study provides a framework for future work.  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