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   20635篇
  免费   1476篇
  国内免费   85篇
耳鼻咽喉   255篇
儿科学   584篇
妇产科学   494篇
基础医学   2653篇
口腔科学   401篇
临床医学   2174篇
内科学   3946篇
皮肤病学   339篇
神经病学   1746篇
特种医学   693篇
外科学   3597篇
综合类   353篇
一般理论   19篇
预防医学   1676篇
眼科学   472篇
药学   1530篇
  5篇
中国医学   15篇
肿瘤学   1244篇
  2023年   132篇
  2022年   197篇
  2021年   475篇
  2020年   280篇
  2019年   444篇
  2018年   479篇
  2017年   308篇
  2016年   346篇
  2015年   409篇
  2014年   566篇
  2013年   751篇
  2012年   1127篇
  2011年   1206篇
  2010年   612篇
  2009年   562篇
  2008年   902篇
  2007年   955篇
  2006年   932篇
  2005年   826篇
  2004年   817篇
  2003年   776篇
  2002年   654篇
  2001年   485篇
  2000年   524篇
  1999年   443篇
  1998年   225篇
  1997年   174篇
  1996年   177篇
  1995年   171篇
  1994年   132篇
  1993年   148篇
  1992年   410篇
  1991年   366篇
  1990年   380篇
  1989年   353篇
  1988年   344篇
  1987年   332篇
  1986年   315篇
  1985年   339篇
  1984年   266篇
  1983年   218篇
  1982年   157篇
  1981年   137篇
  1980年   123篇
  1979年   245篇
  1978年   182篇
  1977年   130篇
  1976年   123篇
  1974年   127篇
  1973年   132篇
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
51.
52.
A 57-year-old woman with cutaneous mastocytosis of 23 years duration developed a hyperpigmented abdominal plaque composed of confluent indurated papules that enlarged for a period of 1 year to 12 x 8 cm. Biopsy showed dermal infiltration by closely packed spindle-shaped mast cells, fibroblasts, collagen, and scattered lymphocytes, predominantly T-suppressor cells. Electron microscopy showed close contact between mast cells, fibroblasts, and lymphocytes. Piecemeal mast cell degranulation and extrusion of mast cell granules was seen, with rare mast cell granules in fibroblasts, and collagen fibers in peripheral and perinuclear endoplasmic reticulum of mast cells. the term Fibrous mastocytoma is suggested for this tumor-like dermal fibrosis, possibly induced by lymphokines.  相似文献   
53.
Gastric acidity, atrophic gastritis, and calcium absorption.   总被引:2,自引:0,他引:2  
The deleterious effects of increased gastric pH on calcium absorption from calcium carbonate supplements were observed about 25 years ago. Increasing use of calcium supplements, especially by the elderly, has raised questions about bioavailability from various calcium sources. Decreased gastric acidity is common in the elderly and in patients taking antiulcer medications. A critical review of the available human studies that have investigated the role of gastric acidity in calcium bioavailability suggests that the effects of increased gastric pH are only apparent when poorly soluble calcium salts are taken after an overnight fast. Soluble calcium sources, such as calcium citrate and calcium from milk, are absorbed normally in elderly subjects with atrophic gastritis. Moreover, calcium carbonate, a relatively insoluble calcium salt, is well absorbed in atrophic gastritis patients if administered with a meal. In order to maximize calcium bioavailability, elderly subjects should increase their calcium intakes to at least recommended levels, preferably by increasing milk consumption. When calcium supplements are used to augment dietary calcium sources, a highly soluble source should be of benefit or calcium carbonate may be taken with a meal.  相似文献   
54.
To elucidate the role of catecholamines in attention deficit disorder, the authors conducted an open 8-week trial of L-tyrosine in 12 adults with attention deficit disorder, residual type. Eight showed marked to moderate clinical response in 2 weeks; at 6 weeks these eight developed tolerance, suggesting that L-tyrosine is not useful in attention deficit disorder, residual type.  相似文献   
55.
56.
57.
R M Syme  C J Wood  H Wong    C H Mody 《Immunology》1997,92(2):194-200
The current studies were performed to determine the contribution of T-cell subsets to lymphocyte proliferation in response to Cryptococcus neoformans, the most common invasive mycosis in acquired immune deficiency syndrome. We demonstrate for the first time that both human CD4 and CD8 cells are activated in response to C. neoformans. Both CD4 and CD8 cells express interleukin-2 receptor alpha (IL-2R alpha) and transferrin receptor and proliferate in response to C, neoformans, however proliferation of CD8 cells was dependent upon CD4 cells. The requirement for CD4 cells was complex, since CD8 enriched cells failed to express mRNA for IL-2, suggesting that CD4-dependent IL-2 production was required for CD8-cell proliferation. However, IL-2 was not sufficient to restore CD8-cell proliferation. These studies provide experimental evidence in humans to support the clinical impression that CD4 cells are important in cryptococcosis, and suggest that the appropriate CD4-derived signals could allow CD8 cells to assist in host defence.  相似文献   
58.
Safety of outpatient tonsillectomy and adenoidectomy   总被引:6,自引:0,他引:6  
Recent changes in reimbursement for tonsillectomy and adenoidectomy have resulted in a large number of these procedures being done on an outpatient basis. There is still considerable controversy, however, as to the safety of this concept. We reviewed the charts of 1000 consecutive patients who underwent these procedures. Three hundred ninety-six procedures were performed as inpatient surgery and 604 were performed as outpatient surgery. Patients were considered as candidates for outpatient surgery if they met specific criteria, such as good overall medical health, no central apnea, normal bleeding history and profile, and had adequate social considerations. The inpatient group included those patients who did not meet the criteria to be outpatients. We compared the complication rates of these two groups with regard to age, type of procedure performed (tonsillectomy, adenoidectomy, adenotonsillectomy), and indication for surgery in order to determine if there was any increased risk of outpatient surgery, despite strict selection criteria. The two groups were similar in their distribution with regards to age, sex, type of procedure, and indication for surgery. The overall complication rate for the entire group was 7.9%, with an 11.8% complication rate for inpatients and 4.1% complications for outpatients. The higher complication rate among the inpatient group is probably a direct result of the selection process because this group included the higher-risk patients. On the basis of these findings, we believe that surgery of the tonsils and adenoids can be performed safely as an outpatient procedure, regardless of age, indication, or procedure, if the candidates for ambulatory surgery are carefully selected by the surgeon.  相似文献   
59.
60.
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