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   2090篇
  免费   106篇
  国内免费   8篇
耳鼻咽喉   54篇
儿科学   33篇
妇产科学   16篇
基础医学   185篇
口腔科学   43篇
临床医学   145篇
内科学   513篇
皮肤病学   79篇
神经病学   76篇
特种医学   51篇
外科学   556篇
综合类   10篇
预防医学   49篇
眼科学   64篇
药学   101篇
中国医学   1篇
肿瘤学   228篇
  2023年   19篇
  2022年   25篇
  2021年   37篇
  2020年   23篇
  2019年   37篇
  2018年   45篇
  2017年   34篇
  2016年   33篇
  2015年   32篇
  2014年   28篇
  2013年   41篇
  2012年   61篇
  2011年   68篇
  2010年   52篇
  2009年   48篇
  2008年   80篇
  2007年   75篇
  2006年   67篇
  2005年   105篇
  2004年   93篇
  2003年   78篇
  2002年   90篇
  2001年   92篇
  2000年   107篇
  1999年   102篇
  1998年   30篇
  1997年   24篇
  1996年   29篇
  1995年   25篇
  1994年   17篇
  1993年   21篇
  1992年   65篇
  1991年   45篇
  1990年   47篇
  1989年   51篇
  1988年   67篇
  1987年   46篇
  1986年   46篇
  1985年   35篇
  1984年   22篇
  1983年   13篇
  1982年   9篇
  1981年   12篇
  1979年   19篇
  1978年   14篇
  1977年   16篇
  1976年   10篇
  1974年   12篇
  1973年   7篇
  1972年   11篇
排序方式: 共有2204条查询结果,搜索用时 15 毫秒
41.
BACKGROUND: Thymus- and activation-regulated chemokine (TARC), which is a CC chemokine receptor (CCR) 4 ligand with ability to recruit Th2 cells to inflammatory sites, is pathogenetically important in allergic rhinitis. Specific immunotherapy (IT), among the most effective therapies for allergic rhinitis, has incompletely understood mechanisms of action. TARC might be involved in some benefits of IT. METHODS: TARC in sera was assayed, obtained from 50 patients with house dust mite allergic rhinitis before and 1 year after beginning IT. Their ages ranged from 6 to 34 years (mean, 10), 30 were male and 20 were female. RESULTS: In patients whose nasal obstruction responded to IT, TARC decreased significantly with IT, while when response was defined in terms of sneezing or rhinorrhea, TARC did not change significantly. CONCLUSION: TARC might be an important target of IT in reducing obstructive allergic rhinitis.  相似文献   
42.
BACKGROUND: In general, serous cystic neoplasms of the pancreas are thought to be benign. Malignant serous cystic neoplasm of the pancreas is a rare clinical entity. CASE REPORT: We report the case of an 87-year-old woman with a serous microcystic neoplasm in the tail of the pancreas that behaved in a malignant fashion. The neoplasm had also invaded the colonic mesentery and splenic hilum. The pancreatic lesion was diagnosed as a large malignant serous cystic neoplasm, and the patient underwent distal pancreatectomy with splenectomy and segmental colectomy. The resected specimen contained a large tumor, 12 x 9 x 8 cm, which occupied the body and tail of the pancreas. Histologically, the tumor was indistinguishable from serous cystadenoma. However, the tumor had invaded surrounding tissues including the splenic vein, and there were splenic invasion and a regional lymph node metastasis. The postoperative course was uneventful. DISCUSSION: There are few reported cases of malignant serous cystic neoplasm, in which malignancy was histologically confirmed in the resected specimen. There are no reports of a negative outcome with complete resection of the tumor. Surgical treatment should be considered for serous cystic neoplasms, especially large ones, because of the malignant potential.  相似文献   
43.
BACKGROUND/AIMS: Preoperative information on arterial anatomy in the peripancreatic and hepatic areas is valuable to any surgeon performing pancreatoduodenectomy. METHODOLOGY: Between 1994 and 1998, 49 patients with periampullary cancer (31 distal bile duct and 18 ampullary tumors) underwent visceral angiography and radical pancreatoduodenectomy with lymphadenectomy. Surgically "significant" arterial variations and their effects on operative management and results were examined retrospectively. RESULTS: Arterial variations were found in 18 patients (37%); 15 (31%) were "significant" and 3 (6%) were "nonsignificant." All 15 patients with "significant" variants required specific type of various preservations of the hepatic arterial system. Intraoperative blood loss, transfused blood units, and operation time were greater in patients with "significant" variations than in patients without (P<0.05). Histopathologic diagnosis, tumor staging, morbidity, and mortality did not differ between the 2 groups. The 5-year survival was 33% for patients with "significant" variations and 63% for patients without (P<0.05). CONCLUSIONS: Information on arterial anatomy in the peripancreatic and hepatic areas is necessary for preoperative evaluation in patients requiring radical pancreatoduodenectomy. Presence of "significant" arterial variations may be considered as one of the negative prognostic factors in patients with periampullary cancer.  相似文献   
44.
45.
We describe a case of hepatocellular carcinoma in a 16-year-old boy whose mother, aunts, uncles, and cousins had liver dysfunction associated with HBs-Ag. Postmortem examination in this case revealed a hepatocellular carcinoma with a trabecular and partially pseudoglandular pattern involving the whole left and most of the right lobe, associated with liver cirrhosis of the postnecrotic type. Postmortem examination of the liver revealed numerous HBs-Ag positive hepatocytes demonstrated by Orcein staining in the nontumorous cirrhotic area, but not in the tumorous hepatocytes. Vertical transmission of HBV from his mother to the patient was suspected, and autopsy findings revealed continuous infection of HBV. Hepatocellular carcinoma in a young patient, especially when associated with HBs-Ag positive liver cirrhosis, as described here is rare in the English and Japanese literature.  相似文献   
46.
Lymph node metastasis determined by histologic examination is an important prognostic indicator in gastric carcinoma. However, prognostic value of lymph node metastasis detected by computed tomography (CT) is unknown. The aim of this study was to evaluate clinical results and prognostic factors of patients with radiologically node-positive gastric carcinoma. The study included 78 patients with primary gastric carcinoma and lymph node metastasis confirmed by CT. The level of lymph node metastasis was simply graded as follows: level I included perigastric nodes; level II included intermediate nodes along the left gastric, common hepatic, and celiac arteries; and level III included distant nodes along the hepatoduodenal ligament, pancreas, spleen, and abdominal aorta. Sixty patients (79%) had stage IV tumors showing one or more of the following: level III lymph node metastasis in 37, pancreatic invasion in 27, peritoneal dissemination in 23, and liver metastasis in 19. Overall 1- and 5-year survival rates were 29% and 6%, respectively, and the 1-year survival rate was significantly influenced by the level of lymph node metastasis on CT (55% for level I, 27% for level II, 7% for level III, P < 0.01). In patients with gastrectomy, prognostic factors were tumor size (<10 cm versus >10 cm, P < 0.01), gross type (localized versus infiltrative, P < 0.01), histologic type (well differentiated versus poorly differentiated, P < 0.01), and curability of the disease (curative versus noncurative, P < 0.01). Our study indicates that prognosis of patients with radiologically node-positive gastric carcinoma is poor because of high frequency of extensive tumor spreads. Patients having only positive level I nodes on CT are candidates for curative gastrectomy, which may offer long-term survival.  相似文献   
47.
The gastrointestinal tract is considered an important endocrine organ for controlling glucose homeostasis via the production of incretins. A 21-year-old man emergently underwent total colectomy due to severe ulcerative colitis, and overt diabetes became evident. Weekly administration of a glucagon-like peptide (GLP)-1 receptor agonist (RA) dramatically improved his glucose control. Levels of GLP-1 or gastric inhibitory polypeptide (GIP) were low at the baseline in the duodenum and serum of the patient. After 11 months of GLP-1RA treatment, his HbA1c worsened again, and intensive insulin therapy was necessary to control his glucose levels. Our report may explain the significance of residual incretin for maintaining the pancreatic β-cell function.  相似文献   
48.
Angiogenesis is a crucial process in the progression of multiple myeloma (MM). Vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) are multifunctional cytokines that potently stimulate angiogenesis including tumour neovascularization. Serum levels of VEGF and HGF were measured in 52 patients with MM by enzyme-linked immunosorbent assay (ELISA). Serum levels of VEGF and HGF were elevated in MM patients compared with healthy controls (VEGF: mean 0.31 ng/ml and 0.08 ng/ml respectively, P < 0.01; HGF: mean 2.17 ng/ml and 0.45 ng/ml, respectively, P < 0.001). In serial samples taken after chemotherapy, serum VEGF and HGF levels were correlated with M-protein levels. Serum levels of VEGF were higher in patients with extramedullary plasmacytomas than in patients without them (P < 0.05). They were also significantly higher in a group of patients who showed poor response to chemotherapy (P < 0.01). Serum levels of HGF were higher in patients with complications such as anaemia, hypercalcaemia and amyloidosis than in patients without these complications (P < 0.01, P < 0.05, P < 0.05 respectively). Both serum VEGF and HGF levels were significant predictors of mortality (P = 0.01, P = 0.02, respectively, log-rank test). The present study demonstrated that serum levels of VEGF and HGF are significantly elevated and dependent on the severity of MM, suggesting that measurement of VEGF and HGF may be useful for assessing disease progression and for predicting the response to chemotherapy in MM patients.  相似文献   
49.
Cine-magnetic resonance imaging (cine-MRI) creates moving pictures by a video system and turbo-flash method that allow for high-speed MRI. This report describes our experience using this new technique for dynamic imaging using the fast spoiled GRASS (SPGR) sequence to study swallowing in patients with dysphagia following radical surgery for oral cancer. We defined two new parameters, laryngeal elevation and the angle of the epiglottis, to quantify swallowing ability by cine-MRI. These variables were markedly different in patients with dysphagia than they were in healthy controls. Cine-MRI not only provides dynamic images of swallowing but can generate objective measures of swallowing ability as well.  相似文献   
50.
We have shown previously that Cyp11b1, an 11beta-hydroxylase responsible for glucocorticoid biosynthesis in the adrenal gland, was induced by cAMP in androgen-producing Leydig-like cells derived from mesenchymal stem cells. We found that Cyp11b1 was induced in male Leydig cells, or female theca cells, when human chorionic gonadotropin was administered in immature mice. Expression of Cyp11b1 in rodent gonads caused the production of 11-ketotestosterone (11-KT), a major fish androgen, which induces male differentiation or spermatogenesis in fish. As in teleosts, plasma concentrations of 11-KT were elevated in human chorionic gonadotropin-treated mice. In contrast to teleosts, however, plasma concentrations of 11-KT were similar in both sexes, despite levels of testosterone, a precursor substrate, being about 20 times higher in male mice. Because expression of 11beta-hydroxysteroid dehydrogenase type 2, was much higher in the mouse ovary than in the testis, conversion of testosterone into 11-KT may occur more efficiently in the ovary. In a luciferase reporter system that was responsive to and activated by androgens, 11-KT efficiently activated mammalian androgen receptor-mediated transactivation. Our results suggest that the androgen metabolic pathway is conserved between teleosts and mammals, despite sexual dominance and reproductive functions of 11-KT being altered during evolution.  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