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   880816篇
  免费   72237篇
  国内免费   1882篇
耳鼻咽喉   13050篇
儿科学   25130篇
妇产科学   25405篇
基础医学   126842篇
口腔科学   25950篇
临床医学   77430篇
内科学   168112篇
皮肤病学   17315篇
神经病学   71688篇
特种医学   35839篇
外国民族医学   171篇
外科学   138917篇
综合类   24947篇
现状与发展   2篇
一般理论   292篇
预防医学   68616篇
眼科学   20839篇
药学   65952篇
中国医学   1606篇
肿瘤学   46832篇
  2018年   7931篇
  2015年   8184篇
  2014年   11741篇
  2013年   17605篇
  2012年   23974篇
  2011年   25071篇
  2010年   14613篇
  2009年   13729篇
  2008年   23601篇
  2007年   25746篇
  2006年   25509篇
  2005年   25114篇
  2004年   24664篇
  2003年   23614篇
  2002年   22694篇
  2001年   36121篇
  2000年   36767篇
  1999年   31190篇
  1998年   9400篇
  1997年   8713篇
  1996年   8608篇
  1995年   8124篇
  1994年   7832篇
  1992年   26894篇
  1991年   26310篇
  1990年   25816篇
  1989年   24865篇
  1988年   23359篇
  1987年   23054篇
  1986年   21911篇
  1985年   21293篇
  1984年   16502篇
  1983年   14127篇
  1982年   8947篇
  1981年   8286篇
  1980年   7746篇
  1979年   16845篇
  1978年   12191篇
  1977年   10257篇
  1976年   9417篇
  1975年   10219篇
  1974年   12717篇
  1973年   12218篇
  1972年   11617篇
  1971年   10764篇
  1970年   10285篇
  1969年   9974篇
  1968年   8946篇
  1967年   8275篇
  1966年   7721篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
221.
222.
223.
224.
Impaired lymph drainage is an inevitable consequence of any form of surgery that disrupts lymphatics, resulting in a degree of lymphoedema that may vary from subtle to dramatic and although classically involving an entire limb, may be more localised, confined to only a small area such as a skin flap. Infection is a well-recognised complication of lymphoedema. However, not all inflammatory episodes occurring in the setting of lymphatic dysfunction can be clearly attributed to infection as this article demonstrates. Five patients presented over a 5-year period with distinctive erysipelas-like inflammation affecting the breast which occurred several weeks following reduction mammaplasty in four patients and breast reconstruction in one patient. No clinical response was obtained with standard antibiotics. This inflammatory problem may represent a previously unreported complication of breast surgery with an incidence of 4% following reduction mammaplasty. Recent research supports the notion that this type of episode is most likely to be due to a non-infective inflammatory process related to lymphatic dysfunction induced by surgery.  相似文献   
225.
226.
The sudden appearance of multiple keratoacanthomas in a patient who has sustained a thermal burn is extremely uncommon. This case report describes a sixty-four-year-old man who noted multiple keratoacanthomas within three weeks after being involved in a gasoline explosion. Multiple keratoacanthomas appear to be a rare complication of thermal cutaneous injury in predisposed persons.  相似文献   
227.
We examined binding to excitatory amino acid and inhibitory amino acid receptors in frozen hippocampal sections prepared from surgical specimens resected from 8 individuals with medically refractory temporal lobe epilepsy. The excitatory receptors studied included N-methyl-D-aspartate (NMDA), strychnine-insensitive glycine, phencyclidine, and quisqualate. The inhibitory receptors studied were gamma-aminobutyric acid type A (GABAA) and benzodiazepine. Excitatory and inhibitory amino acid receptor binding were differentially altered in the patients with temporal lobe epilepsy in comparison to 8 age-comparable autopsy control subjects, and changes in receptor binding were regionally selective in four areas. Binding to phencyclidine receptors associated with the NMDA channel was reduced by 35 to 70% in all regions in the hippocampi of the patients. In contrast, binding to the NMDA recognition site and its associated glycine modulatory site was elevated by 20 to 110% in the cornu ammonis (CA) 1 area and dentate gyrus of the hippocampus of the patients. Binding to these sites was unaffected in area CA4. Binding to the quisqualate-type excitatory amino acid receptor was unchanged in all regions except the stratum lacunosum moleculare CA1, where it was increased by 63%. GABAA and benzodiazepine receptor binding was reduced by 20 to 60% in CA1 and CA4, but unchanged in dentate gyrus. The data indicate that excitatory and inhibitory amino acid receptors are altered in the hippocampus of patients with temporal lobe epilepsy.  相似文献   
228.
Beta-adrenergic receptor density on T cells from healthy humans is greatest on suppressor cells (CD8+, CD28-) and the effect of catecholamines, secreted by the sympathetic nervous system, predominates on this subset. The sympathetic skin response, a measure of sympathetic nervous system function, is absent in most patients with chronic progressive multiple sclerosis (MS). We measured beta-adrenergic receptor density on suppressor cells, cytotoxic cells, and monocytes from patients with chronic progressive MS and healthy control subjects. Control receptor density on suppressor cells was 2.8 +/- 0.3 fmol/10(6) cells versus a density of 5.1 +/- 0.7 fmol/10(6) cells for patients. Cytotoxic cell (CD8+, CD28+) receptor density was 1.4 +/- 0.4 fmol/10(6) cells in control subjects and 0.9 +/- 0.3 fmol/10(6) cells in the patients. Monocytes displayed beta-adrenergic receptor densities of 2.6 +/- 0.4 fmol/10(6) cells in normal individuals and 2.7 +/- 0.4 fmol/10(6) cells in the patient group. CD8 lymphocyte beta-adrenergic receptor densities in patients with relapsing-remitting and those with stable MS were not different from control values, yet were significantly less than the values for patients with chronic progressive MS. We find that mononuclear cells from healthy control subjects and patients with chronic progressive MS proliferate in response to 200 units/ml of recombinant human interleukin-2 (IL-2) similarly. However, IL-2 treatment increased beta-adrenergic receptor density on normal mononuclear cells, but failed to increase it on mononuclear cells from patients with chronic progressive MS.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
229.
230.
This study estimated the effects of changing multiple levels and combinations of nutrition information format, load, expression, and order on consumers' perceptions of label usefulness in purchase decisions using adaptive conjoint analysis. A shopping mall intercept survey, which was administered by a marketing research firm, assessed consumer preferences for 12 label alternatives produced on Campbell's soup cans to portray nutrition information realistically; 252 of 258 respondents completed the computer interactive interview. Consumers significantly preferred the bar graph format to the bar graph/nutrient density and traditional label formats. Consumers considered the bar graph/nutrient density format to be as useful as the traditional label format. There was a highly significant difference among the three levels of information load; the most information load was preferred regardless of nutrient importance. Consumers significantly preferred nutrition information stated in absolute numbers and percentages vs in absolute numbers only in traditional, or in percentages only expressions. There was a significant difference between consumer preferences for the two types of information order. The findings indicate that consumers clearly preferred the nutrition label that displayed all nutrient values using a bar graph format, offered the most information load, and expressed nutrient values using both absolute numbers and percentages. Consumers also preferred nutrition information rearranged in an order that grouped nutrients that should be consumed in adequate amounts on the top, calories in the middle, and nutrients that should be consumed in lesser amounts on the bottom of the label.  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