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   7128篇
  免费   288篇
  国内免费   34篇
耳鼻咽喉   25篇
儿科学   110篇
妇产科学   88篇
基础医学   715篇
口腔科学   150篇
临床医学   478篇
内科学   1828篇
皮肤病学   74篇
神经病学   577篇
特种医学   292篇
外科学   1234篇
综合类   37篇
预防医学   148篇
眼科学   444篇
药学   415篇
中国医学   12篇
肿瘤学   823篇
  2022年   49篇
  2021年   105篇
  2020年   53篇
  2019年   91篇
  2018年   95篇
  2017年   95篇
  2016年   141篇
  2015年   118篇
  2014年   165篇
  2013年   174篇
  2012年   303篇
  2011年   293篇
  2010年   186篇
  2009年   155篇
  2008年   274篇
  2007年   281篇
  2006年   313篇
  2005年   289篇
  2004年   306篇
  2003年   298篇
  2002年   326篇
  2001年   298篇
  2000年   322篇
  1999年   264篇
  1998年   86篇
  1997年   79篇
  1996年   65篇
  1995年   58篇
  1994年   61篇
  1993年   50篇
  1992年   192篇
  1991年   167篇
  1990年   150篇
  1989年   165篇
  1988年   152篇
  1987年   99篇
  1986年   135篇
  1985年   123篇
  1984年   78篇
  1983年   75篇
  1979年   73篇
  1978年   43篇
  1977年   46篇
  1974年   46篇
  1973年   49篇
  1972年   45篇
  1971年   58篇
  1970年   38篇
  1969年   41篇
  1968年   44篇
排序方式: 共有7450条查询结果,搜索用时 15 毫秒
91.
Thickening of the root of the superior mesenteric artery (SMA) was studied by using preoperative sonography in 23 patients with pancreatic cancer and in 10 healthy control subjects. Of the 23 with cancer, 11 had neoplastic involvement of the SMA and 12 did not. Prominent thickening of the area around the SMA with (six patients) or without (five patients) decreased echogenicity compared with the adjacent retropancreatic connective tissue was observed in patients with involvement of the SMA, a finding called the "cuff sign." Mean thickness of the periarterial area in the cancer patients with and without involvement of the SMA and in control subjects were 8.5 mm, 4.0 mm, and 2.9 mm, respectively. With an upper limit of normal of 7.0 mm for the thickness of the SMA, the sensitivity, specificity, and overall accuracy of this sign in the evaluation of involvement of the SMA were 91%, 100%, and 96%, respectively. Decreased echogenicity of the periarterial area was not observed in patients without involvement of the SMA or in control subjects. Our results show that sonographic evidence of periarterial thickening of the root of the SMA (cuff sign), especially with decreased echogenicity, is a reliable finding of tumor infiltration of the SMA in patients with pancreatic carcinoma.  相似文献   
92.
A 3 y.o. boy suffered cardiac arrest after submersion in a winter pond for more than fifteen minutes. He was transferred to our hospital and was successfully resuscitated. Although his neurological condition was severely damaged at the beginning, he started searching objects with his eyes on the 18th hospital day, speaking on the 65th hospital day and walking by himself on the 76th hospital day. His consciousness fully recovered eventually. The treatments consisted of "HYPER" as suggested by Conn AW, et al. and active anti-hypertensive therapy. These treatments and the cold temperature of winter time might have contributed to the good neurological recovery of the patient.  相似文献   
93.
The growth curve of the lens of the Nakano mouse was compared to that of the normal mouse. There was no obvious difference for the first two weeks of age. After this period the growth of the normal lens continued while that of Nakano mouse lens slowed abruptly and eventually ceased. Studies with labeled leucine, however, showed that even after the appearance of the "pin-head" opacity the protein synthesis, although depressed, continued. These findings combined with previous histological observations suggest that new fiber formation is probably unaffected in the early stages of the Nakano cataract. The apparent cessation of lens growth is probably associated with the extensive liquefaction that is observed to occur at the posterior nuclear region.  相似文献   
94.
PURPOSE: Strontium-89 chloride (89Sr) is a new radiopharmaceutical that provides effective pain relief for metastatic bone lesions, and is expected to be available soon in the palliative management for metastatic bone pain in Japan. Because of relatively long physical half life (50.5 days), 89Sr may affect to the radioactive draining-water system by exceeding the limits of activity concentration for radioactive drain. In this article, the influence of 89Sr use on the radioactive drainage system was simulated. METHODS: The standard tank capacity of drainage and draining frequency was determined from the results of questionnaire carried out for the nationwide medical and research institutes where radioisotope treatment are performed. On the assumption that 89Sr of 148 MBq for one therapy was used twice a week and several common radionuclides were used as the same activity as used at Chiba Cancer Center, the influence of 89Sr was estimated. The calculation was performed using the activity contamination ration into the draining-water system of each radionuclide of 0.01, which was legally determined. RESULTS: The simulation revealed that the sum of the contamination ratios of individual radionuclides exceeded a legal value of 1.0 in standard drainage with the capacity of 5 m3 and 10 m3 and draining frequency of 7 times per year. The actual contamination ratios of common radiopharmaceuticals measured at Chiba Cancer Center ranged from 1/100 to 1/1000 of the legal values. CONCLUSION: It is necessary that the legal value of activity contamination ratios into the draining-water system should be reassessed before starting 89Sr therapy.  相似文献   
95.
Desmoplastic fibroma is a relatively uncommon tumor and rarely involves the spine. The authors describe a 20-year-old woman with a thoracic epidural desmoplastic fibroma treated by complete resection and posterior spinal fusion. Four years after surgery, neither the tumor nor clinical symptoms have recurred. Thus, complete resection is considered necessary to treat this tumor.  相似文献   
96.
BACKGROUND: Uroguanylin, originally isolated from urine, is a new natriuretic peptide. Its plasma level is increased in association with renal impairment and fluid retention in patients with renal diseases. METHODS: Uroguanylin concentrations were measured in patients on hemodialysis (HD, n = 76) and those on continuous ambulatory peritoneal dialysis (CAPD, n = 10) using a sensitive ra- dioimmunoassay for human uroguanylin. RESULTS: Plasma concentrations of immunoreactive (ir)-uroguanylin in the patients on HD and CAPD (212.0 +/- 17.4 and 245.3 +/- 39.5 fmol/ml) were significantly higher than the value for the normal controls (5.0 +/- 0.3 fmol/ml). Plasma ir-uroguanylin levels before the start of regular HD were correlated with predialysis excess weight based on their dry weights (r = 0.33, p < 0.01) and with dialysis duration (r = 0.26, p < 0.05). The plasma levels in patients with HD, for whom high-flux membranes were used, were decreased at the end of regular HD as compared with the prior levels (p < 0.05), but not in those who underwent HD with conventional membranes. CONCLUSION: These findings suggest that the plasma ir-uroguanylin level is related to the patient's volume status as well as renal impairment. Whether the accumulation of uroguanylin has a pathological effect has yet to be determined.  相似文献   
97.
98.
99.
PURPOSE: To compare the accuracy of thin-section CT, conventional static MR imaging (conventional MRI), and breathing dynamic echo planar magnetic resonance imaging (BDEPI) in evaluating lung cancer invasion to the chest wall. MATERIALS AND METHODS: Thin-section CT, conventional MRI, and BDEPI were performed preoperatively in 20 patients suspected of having primary lung cancers adjacent to the chest wall on conventional CT. The results of imaging findings were compared with those of surgical and histopathological findings. RESULTS: All patients were confirmed to have no chest wall invasion after surgery. By thin-section CT, 10 of 20 patients were correctly diagnosed as having no chest wall invasion (50% specificity). Two of the 20 patients were incorrectly diagnosed as having chest wall invasion by conventional MRI and BDEPI (90% specificity). CONCLUSION: When chest wall invasion is suspected on CT scans, static and breathing dynamic MRI are recommended to avoid false positive interpretations.  相似文献   
100.
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