首页 | 官方网站   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   31332篇
  免费   1487篇
  国内免费   137篇
医药卫生   32956篇
  2023年   143篇
  2021年   495篇
  2020年   272篇
  2019年   376篇
  2018年   473篇
  2017年   415篇
  2016年   466篇
  2015年   450篇
  2014年   628篇
  2013年   804篇
  2012年   1269篇
  2011年   1352篇
  2010年   814篇
  2009年   720篇
  2008年   1333篇
  2007年   1443篇
  2006年   1423篇
  2005年   1573篇
  2004年   1488篇
  2003年   1452篇
  2002年   1404篇
  2001年   1208篇
  2000年   1280篇
  1999年   1115篇
  1998年   433篇
  1997年   322篇
  1996年   284篇
  1995年   300篇
  1994年   256篇
  1993年   271篇
  1992年   793篇
  1991年   725篇
  1990年   686篇
  1989年   751篇
  1988年   670篇
  1987年   611篇
  1986年   562篇
  1985年   538篇
  1984年   358篇
  1983年   295篇
  1979年   263篇
  1978年   199篇
  1977年   161篇
  1974年   160篇
  1973年   169篇
  1972年   172篇
  1971年   159篇
  1970年   160篇
  1969年   145篇
  1968年   146篇
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
1.
International Journal of Clinical Oncology - The practice of cancer diagnosis disclosure to children has been changed with the times. The regulations of clinical trials in the 2000s might change...  相似文献   
2.
3.
4.
5.
6.
7.
Objective: Induction chemoradiotherapy followed by anatomical resection is a current therapeutic strategy for non-small-cell lung cancer with mediastinal node involvement. Dense peritracheal fibrosis and sclerosis after chemoradiotherapy cause difficult mediastinal node dissection. We evaluated a novel technique to make the mediastinal node dissection easier after induction therapy. Methods: At the end of mediastinoscopic node biopsy for staging of lung cancer, cotton-type collagen was inserted anterior and lateral to the trachea in patients with pathologically confirmed mediastinal node involve-ment (n=45). The induction therapy consisted of concurrent use of platinum-based chemotherapy and hyperfractionated radiotherapy. After the chemoradiotherapy all patients underwent a pulmonary resection with complete mediastinal node dissection 7–12 weeks after the collagen insertion. Surgical findings of the mediastinum and the time for node dissection were compared with those without collagen insertion at mediastinoscopy after chemoradiotherapy (n=5). Results: All five patients without collagen insertion showed sclerotic and fibrotic change of mediastinal nodes with severe adhesion to the trachea. In 42 of 45 patients with collagen insertion (93.3%) the collagen remained unabsorbed and separated the mediastinal nodes from the trachea. Mediastinal node dissection was easily accomplished by removing mediastinal tissues lateral and anterior to the collagen. The rate of mediastinal node separation was significantly higher with collagen insertion than without (p< 0.0001). The times for node dissection in patients with and without collagen insertion showed no significant difference. Conclusion: Cotton-type collagen insertion at staging mediastinoscopy for lung cancer separates the mediastinal nodes from the trachea and makes the node dissection easier after induction chemoradiotherapy.  相似文献   
8.
Anthocyanins, which are responsible for a variety of bright colors (including red, blue, and purple) in fruits, vegetables, and flowers, are consumed as dietary polyphenols. Anthocyanin-containing fruits are thought to decrease coronary heart disease and are used in anti-diabetic preparations. Diabetes is associated with a variety of cardiovascular complications that may be mediated by endothelial dysfunction, and so this study was designed mainly to characterize the influence of a synthesized anthocyanidin derivative (HK-008) over acetylcholine (ACh)-induced relaxation in mesenteric arterial beds isolated from rats. In a glucose-tolerance test in intact rats, HK-008 (30 mg/kg) reduced the glucose level as effectively as the same dose of glibenclamide. The aortic relaxation induced by pinacidil (an ATP-sensitive potassium channel opener) was greatly inhibited by glibenclamide (10 microM), and also significantly inhibited by HK-008 (10 microM). Interestingly, the ACh-induced relaxation in the perfused, preconstricted mesenteric arterial bed was significantly enhanced by HK-008 (10 microM), and this enhancement was significantly attenuated by indomethacin (10 microM). The ACh-induced mesenteric relaxation was impaired by an increase in oxidative stress, viz. superoxide-generating treatment [xanthine oxidase (XO; 0.1 U/ml) plus hypoxanthine (HX; 10 microM)]. However, this impairment was strongly suppressed by HK-008 (10 microM). These results suggest that HK-008 increases endothelium-induced relaxation by suppressing oxidative stress or modulating prostanoids signaling. This compound may therefore be useful against certain cardiovascular disorders.  相似文献   
9.
There is increasing evidence from human and experimental studies that the most important factor governing the outcome in head injury is the severity of diffuse axonal injuries. The authors have experienced 18 cases of severe diffuse axonal injury which showed post-traumatic coma for more than 24 hours and CT findings resembling those of shearing injuries of the cerebral white matter such as have been presented by Zimmerman et al. (1978). The consciousness levels on admission were 6 or less on the Glasgow Coma Scale and all cases were shown clinically to have primary brain stem injury. The main type of head trauma resulted from road traffic accidents (83%). Skull fractures were found in only 5 cases (28%). These findings suggested that acceleration/deceleration injury produce in the patients severe diffuse axonal injury. Initial ICP was below 20 mmHg in 11 cases out of 13 (85%). Parenchymal small hemorrhagic lesions of initial CT were basal ganglia (7 cases), corpus callosum (4 cases), pons (4 cases), midbrain (3 cases) and thalamus (2 cases). Extraparenchymal hemorrhagic lesions included intraventricular hemorrhage (6 cases) and subarachnoid hemorrhage (6 cases). Two autopsied cases of severe diffuse axonal injury (acute case and chronic case) showed remarkable congestion and edema in the deep part of the frontal white matter. Microscopic examination revealed marked axonal degeneration including axonal retraction ball in the corpus callosum, in the internal capsule and in the white matter of the brain stem. Glasgow Outcome Scale of the 18 patients at 3 months after the trauma made us concerned that no patients indicated good recovery or even only moderate disability.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
10.
The biochemical activities of 8 lysosomal acid hydrolases in leukemic cells from 48 patients were examined. Characteristic alterations were found in α-mannosidase, β-galactosidase and N-acetyl-β-glucosaminidase activities of leukemic cells. The level of α-mannosidase activity was much higher in myelo(mono)genous leukemias (AML, AMoL, AMMoL, CML and CMMoL) than in lymphogenous ones (ALL, T-cell leukemia, hairy cell leukemia and CLL) without exception. The β-galactosidase activity also differed as a result of α-mannosidase, except in T-cell leukemia. In T-cell leukemia it was within the range of normal lymphocytes, but in the other lymphogenous leukemias it was significantly below normal. N-acetyl-β-glucosaminidase activity in myelo(mono)genous leukemic cells was above the range of normal granulocytes. The changes in these enzyme levels were consistent. The lymphocytic or myelocytic nature of three cases of acute undifferentiated leukemia could be determined by enzyme studies. In two cases it was lymphocytic and in one it was myelocytic. The enzymatic abnormalities were also found in morphologically mature neutrophils from patients with not only chronic types (CML, CMMoL) but also acute types (AMoL, AMMoL) of leukemias, and were similar to those of their respective leukemic cells. Analysis of lysosomal enzymes (at least three of those mentioned above), can elucidate one of the biochemical properties of leukemic cells and may be valuable in the differentiation of leukemias.  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-23

京公网安备 11010802026262号