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   9152篇
  免费   341篇
  国内免费   45篇
耳鼻咽喉   68篇
儿科学   89篇
妇产科学   186篇
基础医学   1043篇
口腔科学   170篇
临床医学   535篇
内科学   2303篇
皮肤病学   131篇
神经病学   863篇
特种医学   506篇
外科学   1641篇
综合类   39篇
一般理论   1篇
预防医学   249篇
眼科学   89篇
药学   642篇
中国医学   22篇
肿瘤学   961篇
  2023年   59篇
  2022年   113篇
  2021年   195篇
  2020年   82篇
  2019年   116篇
  2018年   139篇
  2017年   108篇
  2016年   143篇
  2015年   131篇
  2014年   229篇
  2013年   262篇
  2012年   444篇
  2011年   474篇
  2010年   304篇
  2009年   232篇
  2008年   414篇
  2007年   526篇
  2006年   508篇
  2005年   489篇
  2004年   484篇
  2003年   486篇
  2002年   529篇
  2001年   241篇
  2000年   277篇
  1999年   262篇
  1998年   164篇
  1997年   128篇
  1996年   126篇
  1995年   88篇
  1994年   86篇
  1993年   59篇
  1992年   164篇
  1991年   154篇
  1990年   143篇
  1989年   135篇
  1988年   133篇
  1987年   111篇
  1986年   105篇
  1985年   105篇
  1984年   61篇
  1983年   53篇
  1981年   31篇
  1979年   57篇
  1975年   34篇
  1974年   26篇
  1973年   27篇
  1972年   34篇
  1971年   26篇
  1969年   34篇
  1968年   28篇
排序方式: 共有9538条查询结果,搜索用时 15 毫秒
61.
62.
Peripheral low-density area of hepatic tumors: CT-pathologic correlation   总被引:4,自引:0,他引:4  
To aid in the distinction between colorectal cancer metastasis to the liver and hepatocellular carcinoma, findings on computed tomographic (CT) scans taken more than 5 minutes after contrast material administration ("late-enhanced CT scans") and pathologic findings were compared. Late-enhanced CT scans of metastatic adenocarcinoma showed a peripheral low-density area (PLDA) that corresponded to viable tumor and a central high-density area that represented fibrous connective tissue. This phenomenon was recognized in 15 of 20 (75%) patients with metastatic adenocarcinoma and in one of 50 (2%) patients with hepatocellular carcinoma. Late-enhanced CT scans may be useful in distinguishing between metastatic nonmucinous colorectal cancer and hepatocellular carcinoma.  相似文献   
63.
A modified technique for handsewn anastomosis after abdominoperineal pull-through resection is described. The technique is a continuous locked modification of the Gambee suture. Simplicity, rapidity, reliability, and firmness are the advantages of this technique.  相似文献   
64.
A 45-year-old male was admitted to our hospital for investigation of a nodular shadow in segment 5 of the right lung on a chest computed tomogram. A right middle lobectomy with mediastinal lymph node dissection was performed under a diagnosis of lung cancer, and histologic examination confirmed small cell carcinoma. There were sarcoid reactions in the resected lymph nodes and the lung parenchyma, but no signs of systemic sarcoidosis were evident. Sarcoid reactions are rarely observed in the regional lymph nodes draining malignant tumors. Moreover, while they are most common in squamous cell carcinoma of the lung, they extremely rare in small cell carcinoma. To our knowledge, this is only the third report of this unusual entity in the English and Japanese literature.  相似文献   
65.
Tanaka YZ  Koyama T  Mikami A 《Neuroreport》1999,10(2):393-397
To investigate neuronal mechanisms that integrate different visual modalities such as motion and shape, neuronal activities in the superior temporal polysensory area (STP) were recorded from monkeys that were watching rotating images. In total, 194 neurons were identified as visually responsive. Of these, 73 neurons (38%) showed differential response depending on both shape and direction of motion (MS neurons). Of these 73 neurons, 21 (29%) were identified as reversal type MS neurons (MSr neurons), that is, they responded to an opposite preferred direction when the shape was different. The results confirm that neurons in the STP can be simultaneously activated by different attributes of visual stimuli. The data also suggest that individual STP neurons can process more than one type of visual stimulus.  相似文献   
66.
A novel experimental model of free radical-induced emesis for screening anti-emetic compounds from natural sources was established. 2,2'-Azobis(2-amidinopropane) dihydrochloride (AAPH) dissolved in liposome induced emesis in young chickens, and the emesis was prevented by antioxidants including N-(2-mercaptopropionyl)-glycine (MPG), alpha-tocopherol, and L-ascorbic acid. Tropiseton, a serotonin receptor antagonist, also prevented emesis induced by AAPH. Known anti-emetic drugs and anti-emetic principles from natural sources also showed significant retching inhibition in the experiment using this system.  相似文献   
67.
Copper IUDs and polyethylene IUDs were inserted in Clauberg rabbits. Proliferation of endometrium caused by exogenous progesterone was markedly inhibited in the rabbits with the copper IUD. Maximum proliferation was seen in the contralateral uterine horn of the rabbits with polyethylene IUDs. The concentration of Cu-ion in the endometrium in the horn with Cu-IUD showed a higher level as 19.5 ug/g wet wt. than that in the control horn, 2.5 ug/g wet wt. This effect corresponds to the addition of Cu-ion in a concentration of higher dosage to the endometrium of the control horn. In the case of women with normal menstrual cycles, the increase in a concentration of Cu-ion in the endometrium with Cu-IUD was lower than 10-5M; in the control women the concentration was 1.6 ug/g wet wt. of endometrium. The histological dating of endometrial specimens (E-B date) with Cu-IUD was examined and compared with expected date of the cycle determined by BBT date. Cu-IUD did not induce any significant discrepancy in both dating. The mechanism of increasing contraceptive effect with Cu-ion was considered to be a little different than in rabbits. (Author's Modified)  相似文献   
68.
T Koyama  N Nakamura  T Wada  J Arita  M Matoba  M Kubo 《Brain and nerve》1991,43(12):1163-1168
A rare case of cranial fasciitis in a 1-year-old boy arising in the temporoparietal bone has been described. In 1990, Lauer and Endinger first reported cranial fasciitis, which is a benign subcutaneous tumor of the head developing from the deep fascia or the cranial periosteum and showing a pathological finding characterized by proliferation of fibroblasts. They described this tumor as "cranial fasciitis of childhood" in view of a high incident in infants and child. Cranial fasciitis grows rapidly in the scalp without pain, but its mean size is 2.5-3cm. Cranial fasciitis is closely related a clinical course and pathological findings to nodular fasciitis, which is also a benign proliferative fibroblast tumor developing from the subcutaneous muscular layers of the trunk and extremities (especially, the forearms), which was reported by Konwaler in 1955. However, cranial fasciitis differs from nodular fasciitis in that it is associated with the skull bone and, in many cases, the tumor destroys the inner and outer table of the skull and adheres to the dura mater. Cranial fasciitis should be considered to be a variant of nodular fasciitis. Neurosurgeons should be aware of this entity in the differential diagnosis of a firm lesion of the scalp in children. A brief review of the literature disclosed only 17 cases in the world. This case report is the first one of cranial fasciitis in Japan.  相似文献   
69.
AIM: A number of imaging techniques have been used for the pre-operative assessment of patients for lung volume reduction surgery (LVRS). We evaluated whether data currently acquired from perfusion scintigrams and cine MR of the diaphragm are obtainable from high resolution CT (HRCT) of the thorax. MATERIALS AND METHODS: Thirty patients taking part in a randomized controlled trial of LVRS against maximal medical therapy were evaluated. HRCT examinations (n= 30) were scored for (i) the extent and distribution of emphysema; (ii) the extent of normal pulmonary vasculature; and (iii) diaphragmatic contour, apparent defects and herniation. On scintigraphy, (n= 28), perfusion of the lower thirds of both lungs, as a proportion of total lung perfusion (LZ/T(PERF)), was expressed as a percentage of predicted values (derived from 10 normal control subjects). On cine MR (n= 25) hemidiaphragmatic excursion and coordination were recorded. RESULTS: Extensive emphysema was present on HRCT (60% +/- 13.2%). There was strong correlation between the extent of normal pulmonary vasculature on HRCT and on perfusion scanning (r(s)= 0.85, P< 0.00005). Hemidiaphragmatic incoordination on MR was weakly associated with hemidiaphragmatic eventration on HRCT (P= 0.04). CONCLUSION: The strong correlation between lung perfusion assessed by HRCT and lung perfusion on scintigraphy suggests that perfusion scintigraphy is superfluous in the pre-operative evaluation of patients with emphysema for LVRS.  相似文献   
70.
We analyzed 7 pituitary adenomas in patients with multiple endocrine neoplasia type 1 (MEN1). Their incidence was 1.6% among 450 patients with pituitary adenomas which had been treated surgically in our department between 1978 and 1999. The age, gender, symptoms, type of hormone secretion, pathological and operative findings in the MEN1 patients were not apparently different from those in the non-MEN1 patients. Incidence of non-functioning pituitary adenomas, however, was more frequently encountered in our series than that in previous reports among Caucasian people. One patient who had 5 previous operations for the MEN tumors died following postoperative subarachnoid hemorrhage. Four of the seven patients presented initial symptoms related to pituitary adenomas and increased serum Ca level was retrospectively recognized in three of the four at the time of treatment for the pituitary adenomas.  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