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   19537篇
  免费   1051篇
  国内免费   136篇
耳鼻咽喉   163篇
儿科学   365篇
妇产科学   169篇
基础医学   2603篇
口腔科学   347篇
临床医学   1372篇
内科学   5286篇
皮肤病学   261篇
神经病学   1284篇
特种医学   833篇
外科学   3268篇
综合类   85篇
预防医学   597篇
眼科学   325篇
药学   1188篇
  1篇
中国医学   26篇
肿瘤学   2551篇
  2023年   212篇
  2022年   392篇
  2021年   627篇
  2020年   299篇
  2019年   406篇
  2018年   545篇
  2017年   375篇
  2016年   442篇
  2015年   426篇
  2014年   566篇
  2013年   643篇
  2012年   1088篇
  2011年   1152篇
  2010年   629篇
  2009年   555篇
  2008年   955篇
  2007年   957篇
  2006年   939篇
  2005年   893篇
  2004年   864篇
  2003年   859篇
  2002年   814篇
  2001年   526篇
  2000年   530篇
  1999年   467篇
  1998年   266篇
  1997年   206篇
  1996年   209篇
  1995年   166篇
  1994年   153篇
  1993年   131篇
  1992年   338篇
  1991年   278篇
  1990年   275篇
  1989年   262篇
  1988年   233篇
  1987年   196篇
  1986年   217篇
  1985年   203篇
  1984年   158篇
  1983年   122篇
  1982年   65篇
  1979年   139篇
  1978年   89篇
  1977年   77篇
  1975年   65篇
  1974年   67篇
  1973年   62篇
  1971年   61篇
  1969年   60篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
BACKGROUND: Relationship between post administrative changes in plasma drug levels and bronchodilation remains unknown. In this study, we measured plasma levels of procaterol, a beta2-agonist, when being inhaled through nebulizers in children with bronchial asthma to examine relationship between improvement of pulmonary function and the plasma levels. METHOD: Six asthmatic children with the mean age of 9.8 years, inhaled 0.3 ml of 0.01% procaterol solution through a nebulizer. We examined changes in pulmonary function and plasma procaterol levels before and after inhalation. RESULTS: Procaterol was detected in the plasma 2 minutes after inhalation when it already rose to the maximum level, and kept the steady until showing a decline in 30 minutes. The measured highest value was 87.8+/-45.1 pg/ml. FEV 1.0 remarkably increased 2 minutes after inhalation and was maintained until 60 minutes after inhalation. Other lung function parameters also improved. There was no significant change in the heart rate, but serum potassium concentrations significantly dropped in all patients 60 minutes after inhalation. CONCLUSION: Plasma procaterol levels promptly rose to the peak at 2 minutes after inhalation and decreased 30 minutes later. Improvement of pulmonary function started promptly at minutes after inhalation and it became a peak 60 minutes later.  相似文献   
63.
With the application of liver transplantation for patients with biliary atresia (BA), we have had the opportunity to review the clinicopathologic features of the native livers from 10 transplanted BA patients. A single large nodule at porta hepatis (hilar nodule) was noted in three of 10 patients, and an ill-defined nodule-like lesion at porta hepatis was present in two other patients. The three BA patients with hilar nodules were long-term survivors, compared to the patients with nodule-like and those without nodules. The hilar nodules measured between 5.0 cm and 8.0 cm and histologically, they were partly surrounded by fibrous septa with relatively well-preserved liver architectures and fewer inflammatory cells at the portal triads when compared to the surrounding cirrhotic lesions. No nuclear or cellular atypia was observed. Proliferating cell nuclear antigen labeling index was higher in the surrounding cirrhotic lesions than the hilar nodules. The nodule-like lesions at porta hepatis also showed similar light microscopic and immunohistochemical features as the hilar nodules. These hilar nodules did not seem to contain any malignant potential. The benign histology with relatively well-preserved liver architecture and the preferential site of occurrence at porta hepatis where bile seemed to flow more smoothly, suggested possible residues of less-affected hepatic tissues.  相似文献   
64.
65.
66.
Transgenic (Tg) mice overexpressing human thioredoxin (TRX), a small redox-active protein, were produced to investigate the role of the protein in a variety of stresses. Bone marrow cells from TRX-Tg mice were more resistant to ultraviolet C-induced cytocide compared with those from wild type (WT) C57BL/6 mice. TRX-Tg mice exhibited extended median and maximum life spans compared with WT mice. Telomerase activity in spleen tissues in TRX-Tg mice was higher than that in WT mice. These results suggest that overexpression of TRX results in resistance against oxidative stress and a possible extension of life span without apparent abnormality in mammals.  相似文献   
67.
In this study, we isolated and characterized a murine counterpart of the human Arpp (hArpp) gene. Sequence analysis revealed that the murine Arpp (mArpp) gene is almost identical to the Ankrd2 gene, which has recently been isolated as a mouse gene induced in stretched skeletal muscle. The mArpp gene encodes a protein of 332 amino acids that contains four well-conserved ankyrin-repeat domains in the central portion of the protein. The amino acid sequence of mArpp protein (mArpp) is highly homologous to that of mouse cardiac-restricted ankyrin-repeat protein (Carp), which is proposed to be a putative genetic marker for cardiac hypertrophy. Immunohistochemical analysis revealed that mArpp is preferentially expressed in type 1 skeletal muscle fibers, and that mArpp is localized in both the nucleus and the sarcomeric I-band of muscle fibers, suggesting that Arpp may function as a nuclear and sarcomeric protein. Furthermore, mArpp was also expressed in neurons of the cerebellum and cerebrum, the islets of Langerhans in the pancreas, and the esophageal epithelium, suggesting that mArpp may play a functional physiologic role in brain, pancreas, and esophagus as well as in type 1 muscle fibers. Interestingly, although mArpp was localized in both nucleus and cytoplasm in neurons, its localization was restricted to nucleus in pancreas and esophagus, suggesting that intracellular localization of mArpp is regulated in a tissue-specific manner. Furthermore, we found that mArpp- and Carp-expression in skeletal muscle were markedly up-regulated after denervation. Although the elevated expression level of Carp was kept only for two weeks after denervation, that of Arpp was kept at least for 4 weeks, suggesting that mArpp and Carp may play distinct functional roles in denervated skeletal muscle.  相似文献   
68.
A 15-month-old male infant who had pre- and postnatal overgrowth, accelerated bone maturation and characteristic facial appearance was described. Although a Japanese female with Weaver syndrome previously reported had slightly different clinical manifestations from others, our patient had typical clinical features of Weaver syndrome. We suggest that a genetic mutation of the syndrome may be the same in Japanese as other ethnic groups and that Weaver syndrome may be an autosomal dominant disorder with variable expressions.  相似文献   
69.
70.
Hereditary coproporphyria (HCP) is an acute hepatic porphyriawith autosomal dominant inheritance, but with a variable degreeof clinical expression. Molecular cloning, sequencing and expressionof the defective gene for coproporphyrinogen oxidase (CPO) ina patient with HCP were carried out. Enzyme assays revealedthat CPO activity in EBV-transformed lymphoblastoid cells fromthe proband and one of her sisters was  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