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   395590篇
  免费   24969篇
  国内免费   2902篇
耳鼻咽喉   5281篇
儿科学   8498篇
妇产科学   10246篇
基础医学   55003篇
口腔科学   12223篇
临床医学   31169篇
内科学   82284篇
皮肤病学   8842篇
神经病学   28506篇
特种医学   14680篇
外国民族医学   82篇
外科学   63596篇
综合类   10015篇
现状与发展   1篇
一般理论   65篇
预防医学   17996篇
眼科学   9852篇
药学   32171篇
  1篇
中国医学   2218篇
肿瘤学   30732篇
  2021年   2931篇
  2019年   2984篇
  2018年   4838篇
  2017年   3670篇
  2016年   3834篇
  2015年   4331篇
  2014年   6072篇
  2013年   7899篇
  2012年   10864篇
  2011年   11145篇
  2010年   6712篇
  2009年   6299篇
  2008年   10277篇
  2007年   11212篇
  2006年   11179篇
  2005年   10181篇
  2004年   9670篇
  2003年   9291篇
  2002年   8981篇
  2001年   28674篇
  2000年   29220篇
  1999年   24065篇
  1998年   5389篇
  1997年   4410篇
  1996年   4010篇
  1995年   3588篇
  1994年   3221篇
  1993年   2930篇
  1992年   16339篇
  1991年   15085篇
  1990年   14438篇
  1989年   14201篇
  1988年   12811篇
  1987年   12281篇
  1986年   11328篇
  1985年   10540篇
  1984年   7044篇
  1983年   5714篇
  1982年   2781篇
  1979年   5582篇
  1978年   3418篇
  1977年   3035篇
  1975年   2698篇
  1974年   3103篇
  1973年   2921篇
  1972年   2881篇
  1971年   2822篇
  1970年   2582篇
  1969年   2613篇
  1968年   2314篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
A nationwide survey of transient hyperammonemia in newborns was carried out in Japan. A total of 18 patients, consisting of 12 male and 6 female infants, were reported from 11 facilities. These neonates exhibited hyperammonemia with plasma ammonia levels in the range from 124 to 6256 micrograms/dl. Four newborn infants of the 18 died in the neonatal period, and an additional one died in the early infancy. Among the 13 infants who were alive at the time of this survey, 6 had neurological sequelae, including mental retardation, spastic quadriplegia and epilepsy. The multivariate analysis revealed that the Apgar score at 1 minute, peak plasma ammonia concentration, birth weight and sex were significant factors affecting the prognosis of life.  相似文献   
52.
One of the consequences of increased intracellular calcium in response to a variety of physiological stimuli is the calcium activation of cytosolic proteases. Unlike lysosomal proteases with broad specificity, these calcium-activated neutral proteases show limited proteolysis of a restricted set of substrate proteins suggesting they may play a regulatory role in cellular physiology. In this study we show that the neural cell adhesion molecules NCAM-180 and N-cadherin are substrates for such endogenous calcium-activated neutral proteases. In contrast, a third neural cell adhesion molecule G4/L1 was not susceptible to calcium-activated proteolysis. The threshold for activation of NCAM and N-cadherin proteolysis is in the micromolar range of calcium suggesting that NCAM and N-cadherin are substrates for a mu-type calpain (calpain I). The site recognized by this protease is within intracellular domains of NCAM-180 and N-cadherin which are important for their interaction with cytoskeletal components. These results suggest that calcium-activated proteolysis at these sites in vivo could disrupt the linkage between extracellular ligand binding to these adhesion molecules and the normal intracellular effectors of such extracellular binding events.  相似文献   
53.
We report an 80-year-old Japanese male with four primary malignant tumors: malignant melanoma, prostatic cancer, malignant lymphoma, and renal cell carcinoma, which occurred in that respective order. The combination of malignant melanoma and malignant lymphoma is rare. The patient was treated with BCG after an operation for malignant melanoma. He was also treated with cobalt 60 irradiation after an operation for prostatic cancer. We also discuss other reports of multiple malignant tumors and suggest some possible causes of this patient's primary malignant tumors.  相似文献   
54.
55.
56.
57.
With the increased use of indwelling central venous catheters, increasing numbers of cases of Rhodotorula fungemia have been observed in patients with neoplasia and neutropenia. In most patients with catheter-related Rhodotorula fungemia, the condition has been treated with broadspectrum antibiotics. We report two cases of central venous catheter-related Rhodotorula rubra fungemia that occurred in patients with acute myeloblastic leukemia. Both patients were in a state of neutropenia. One patient was treated with amphotericin B and his central venous catheter was removed, but he died of Klebsiella pneumoniae bacteremia. The other patient was treated with amphotericin B and discharged, with a central venous catheter, after recovery from neutropenia. Although the management of catheter-related Rhodotorula fungemia infections remains controversial, resolution of the underlying disease is more important than catheter removal for recovery from Rhodotorula rubra fungemia. Received: August 22, 2001 / Accepted: October 8, 2001  相似文献   
58.
59.
In rodents, chronic estrogenization has been shown to induce degeneration of dendrites and myelin figures in the hypothalamic arcuate nucleus adjacent to peroxidase-positive astrocyte processes. Because in this brain region estradiol is metabolized to 2-hydroxyestradiol (catecholestrogen), we hypothesized that the latter may be oxidized by the astrocytic peroxidase activity to cytotoxic ortho-semiquinones as occurs in peripheral tissues. Cysteamine induces nonenzymatic peroxidase activity in cultured astroglia identical to that observed in vivo. Using electron spin resonance, we demonstrate robust peroxidase-catalyzed oxidation of 2-hydroxyestradiol and dopamine by cysteamine-pretreated astrocyte cultures relative to untreated controls. These results implicate the peroxidase-positive astrocytes in the pathogenesis of estradiol-related hypothalamic damage, parkinsonism, and other free-radical-related neurologic disorders.  相似文献   
60.
A new macrolide antibiotic, clarithromycin (TE-031, A-56268), was studied for its clinical efficacy in the field of pediatrics. Patients treated were infants and children ranging from 2 months to 11 years old suffering from acute bronchitis in 5 cases, acute tonsillitis in 2 cases, Mycoplasma pneumonia in 2 cases, pertussis in 6 cases, scarlatina in 1 case and acute enteritis in 2 cases, a total of 18 cases. TE-031 was administered 19.7-43.5 mg/kg in daily doses and lengths of treatment ranged from 4 to 19 days. As regards to its clinical efficacy, good or excellent results were obtained in all cases: excellent in 11 cases and good in 7 cases. No clinical side effects nor abnormal laboratory test values obviously attributable to TE-031 were observed.  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