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   1726004篇
  免费   125187篇
  国内免费   3953篇
耳鼻咽喉   21963篇
儿科学   56273篇
妇产科学   46621篇
基础医学   245171篇
口腔科学   49524篇
临床医学   153412篇
内科学   341208篇
皮肤病学   39117篇
神经病学   133326篇
特种医学   64934篇
外国民族医学   242篇
外科学   262844篇
综合类   39082篇
现状与发展   4篇
一般理论   531篇
预防医学   125234篇
眼科学   40565篇
药学   125703篇
  7篇
中国医学   4589篇
肿瘤学   104794篇
  2021年   13443篇
  2019年   14027篇
  2018年   20582篇
  2017年   15714篇
  2016年   17183篇
  2015年   19597篇
  2014年   27041篇
  2013年   38895篇
  2012年   54258篇
  2011年   57060篇
  2010年   33688篇
  2009年   31435篇
  2008年   52963篇
  2007年   56346篇
  2006年   56780篇
  2005年   54078篇
  2004年   52322篇
  2003年   49645篇
  2002年   47862篇
  2001年   92735篇
  2000年   94513篇
  1999年   77827篇
  1998年   20153篇
  1997年   17627篇
  1996年   17713篇
  1995年   17023篇
  1994年   15555篇
  1993年   14316篇
  1992年   57915篇
  1991年   55768篇
  1990年   53390篇
  1989年   51261篇
  1988年   46554篇
  1987年   45330篇
  1986年   42651篇
  1985年   40353篇
  1984年   29610篇
  1983年   25137篇
  1982年   14023篇
  1979年   25696篇
  1978年   17738篇
  1977年   15035篇
  1976年   13992篇
  1975年   14713篇
  1974年   17763篇
  1973年   17060篇
  1972年   15773篇
  1971年   14578篇
  1970年   13529篇
  1969年   12610篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
To determine if impaired dichotic performance in patients with dementia of the Alzheimer type is due to the inability to divide attention or the inability to perceive degraded auditory stimuli, we measured performance on tasks of both dichotic and degraded monotic speech materials. We also examined whether perception of degraded speech stimuli presented monaurally is related to abnormalities of temporal lobe anatomy and physiology, as we have shown for dichotic performance. Although the patients were impaired on both dichotic and monotic tests, significantly greater impairment was seen on the dichotic test. Our earlier finding of a significant relation between dichotic performance and measures of anterior temporal lobe atrophy and reduced glucose metabolism was replicated, but no significant relation was found between monotic tests and measures to temporal lobe integrity. We conclude that the inability to divide attention, rather than abnormal processing of degraded stimuli per se, is reflected in poor dichotic performance in patients with dementia of the Alzheimer type, and that dichotic performance, unlike degraded monotic perception, depends directly on the integrity of temporal cortex in these patients.  相似文献   
992.
993.
Many older treatments should not be discarded because of newer modalities. Various dermatologic disorders may be controlled effectively by prescribing these older topical agents.  相似文献   
994.
As the fields of astronomy, cosmology, and space travel move rapidly forward, so must space medicine. The manned space program and medical knowledge and support have developed in tandem. Dermatology will play a fundamental role in survival during space flight. This paper reviews past, present, and future accomplishments of the space program as they relate to medicine and characterizes some of dermatology's multiple roles in the future. It further explores the immunologic alterations noted during space flight and the attendant implications for health and well-being both in flight and on return to Earth, or to an Earthlike environment.  相似文献   
995.
Processing of a protein antigen into fragments is believed to be a prerequisite for its presentation by the antigen-presenting cell to the T cell. This model would predict that, in oligomeric proteins, T cells prepared with specificity for regions that are buried within subunit association surfaces should recognize the respective regions in vitro equally well on the isolated subunit or on the oligomer. Three hemoglobin (Hb) alpha-chain synthetic peptides, corresponding to areas that are situated either completely [alpha-(31-45)] or partially [alpha-(41-45) and alpha-(81-95)] within the interface between the alpha and beta subunits of Hb, and a fourth peptide representing a completely exposed area in tetrameric Hb were used as immunogens in SJL/J (H-2s) mice. Peptide-primed T cells were passaged in vitro with the respective peptide to obtain peptide-specific T-lymphocyte lines. T-cell clones were isolated from these lines by limiting dilution. T-cell lines and clones that were specific for buried regions in the subunit association surfaces recognized the free peptide and the isolated subunit but not the Hb tetramer. On the other hand, T cells with specificity against regions that are not involved in subunit interaction and are completely exposed in the tetramer recognized the peptide, the isolated subunit, and the oligomeric protein equally well. The responses of the T-cell lines and clones were major histocompatibility complex-restricted. Since the same x-irradiated antigen-presenting cells were employed, the results could not be attributed to differences or defects in Hb processing. The findings indicate that in vitro the native (unprocessed and undissociated) oligomeric protein was the trigger of major histocompatibility complex-restricted T-cell responses.  相似文献   
996.
Endoscopic pictures of the bronchi were studied in 509 new cases of pulmonary tuberculosis. Tuberculosis of the bronchi and its aftereffects such as cicatricial lesions were detected in 31.1 per cent of the children and adolescents, 7.9 per cent of the adults at the age of 18 to 29 years, 9.0 per cent of the adults at the age of 30 to 55 years and 14.7 per cent of the adults at the age of 56 to 75 years. Nonspecific endobronchitis was diagnosed in 27.9 per cent of the children and adolescents, 44.9 per cent of the adults at the age of 18 to 29 years, 46.3 per cent at the age of 30 to 55 years and 44.1 per cent at the age of 56 to 75 years. The incidence and nature of tuberculosis of the bronchi and nonspecific endobronchitis were not related to the patients' age.  相似文献   
997.
An ELISA technique has been developed to detect HBsAg in the sera of leprosy patients. Out of ninety-two serum samples taken from untreated leprosy patients, 10 samples were positive for HBsAg. The ELISA used in the present investigation is a low cost, reliable and sensitive marker of HBsAg. It is better than lesser sensitive (haemagglutination and counterimmunoelectrophoresis), costly and hazardous (radioimmunoassay) techniques and is therefore recommended for routine use.  相似文献   
998.
The authors report a case of massive Trichuris trichiura infection, resulting in severe anaemia and congestive cardiac failure in a 9-year-old Iban boy, who was resistant to the usual oral anthelmintic treatment, but promptly responded to mebendazole retention enema. This patient also had an associated Entamoeba histolytica infection.  相似文献   
999.
1000.
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