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   24646篇
  免费   1854篇
  国内免费   88篇
耳鼻咽喉   396篇
儿科学   899篇
妇产科学   384篇
基础医学   2515篇
口腔科学   549篇
临床医学   2280篇
内科学   5415篇
皮肤病学   565篇
神经病学   1299篇
特种医学   1405篇
外国民族医学   1篇
外科学   4605篇
综合类   335篇
一般理论   15篇
预防医学   1181篇
眼科学   826篇
药学   2060篇
中国医学   38篇
肿瘤学   1820篇
  2023年   225篇
  2022年   400篇
  2021年   993篇
  2020年   477篇
  2019年   819篇
  2018年   956篇
  2017年   613篇
  2016年   652篇
  2015年   685篇
  2014年   1027篇
  2013年   1198篇
  2012年   1748篇
  2011年   1718篇
  2010年   894篇
  2009年   837篇
  2008年   1287篇
  2007年   1234篇
  2006年   1139篇
  2005年   997篇
  2004年   899篇
  2003年   756篇
  2002年   656篇
  2001年   595篇
  2000年   558篇
  1999年   509篇
  1998年   254篇
  1997年   204篇
  1996年   214篇
  1995年   194篇
  1994年   167篇
  1993年   158篇
  1992年   278篇
  1991年   292篇
  1990年   261篇
  1989年   251篇
  1988年   233篇
  1987年   257篇
  1986年   215篇
  1985年   206篇
  1984年   134篇
  1983年   142篇
  1982年   107篇
  1981年   93篇
  1980年   86篇
  1979年   135篇
  1978年   93篇
  1977年   87篇
  1976年   69篇
  1975年   71篇
  1973年   88篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
OBJECTIVE: To evaluate impressions and usage of sinus surgery image-guided surgical (IGS) systems by ENT surgeons in the United States. STUDY DESIGN AND SETTING: A survey was mailed to selected practicing ENT physicians, investigating regional information, practice type, IGS usage patterns, perceived benefits and limitations, and usage of the 61795 surgery code. RESULTS: Seventy-three percent of respondents use IGS. Nonusers respond that it provides no benefit or is too expensive. Eighty percent of respondents replied that IGS may allow for increased safety in certain procedures. Most users attempt reimbursement with the 61795 code. CONCLUSION: IGS usage is increasing but appears to be perceived as expensive and nonbeneficial in certain situations. Most respondents, however, felt that IGS may lead to safer surgery in certain situations, including revision and frontal procedures. Several factors appear to limit routine use including ease of use, technical setup, code reimbursement, and initial purchase costs. SIGNIFICANCE: IGS use appears to be increasing. The most frequent users appear to agree with the previously issued AAO-HNS guidelines regarding appropriate indications. Expanded use may depend on ease of use, reimbursement, and affordability. EBM rating: D-5.  相似文献   
22.
23.
Cocaine is a potent dopamine agonist that frequently stimulates the central nervous system and is often manifested by increased psychomotor activity, impulsivity, euphoria, and rapid thoughts. Attention deficit disorder (ADD) and bipolar disorder also present with physical restlessness, racing thoughts, distractibility, and mood instability. Although these three disorders rarely appear in the same individual, they are important differential diagnoses when considering any one illness with the above symptom complexes. We report two cases of cocaine abuse with ADD residual type in patients who were previously diagnosed as having atypical bipolar disorder. The adverse effects were reversed by the dopamine agonist bromocriptine.  相似文献   
24.
BACKGROUND: Pravastatin and simvastatin prolong survival and reduce transplant-related coronary vasculopathy, although low-density lipoprotein (LDL) lowering with these agents is only modest. The objective of this study was to assess the safety of moderate dose atorvastatin and its efficacy when prior treatment with another statin had failed to lower LDL to < 100 mg/dl. METHODS: Data from 185 patients were retrospectively evaluated for adverse events, duration of exposure (person-days), and the mean atorvastatin dose exposure. Changes in lipid parameters, and prednisone and cyclosporine doses were determined. RESULTS: Safety: 48 patients received atorvastatin for 24,240 person-days at a mean dose exposure of 21 +/- 10 mg. Rhabdomyolysis, myositis, myalgias, and hepatotoxicity occurred in 0, 2, 2, and 0 patients, respectively. All events occurred at the 10-mg dose, within the first 3 months, and were rapidly reversible with atorvastatin discontinuation. Efficacy: Thirty-four patients evaluable for efficacy analyses had a pre-atorvastatin LDL of 145 +/- 38 mg/dl on the following statins: pravastatin (n = 30, 40 +/- 0mg), fluvastatin (n = 3, 33 +/- 12 mg), simvastatin (n = 1, 40 mg). After atorvastatin (21 +/- 9 mg/day) for 133 +/- 67 days, LDL was reduced to 97 +/- 24 mg/dl (relative reduction 31 +/- 20%, p < 0.0001). At the end of the observation period (418 +/- 229 days, atorvastatin final dose 24 +/- 14 mg/day), LDL was further decreased to 88 +/- 23 mg (relative reduction 37 +/- 17%, p < 0.0001). CONCLUSION: Atorvastatin, when used at moderate doses and with close biochemical and clinical monitoring, appears to be safe and is effective in aggressively lowering LDL in heart transplant recipients when treatment with other statins has failed to achieve LDL goals.  相似文献   
25.
The possible involvement of ionotropic and metabotropic quisqualate (QA) receptors in neuronal plasticity was studied in cultured glutamtergic cerebellar or hippocampal cells in terms of the specific activity of phosphate-activated glutaminase, an enzyme important in the synthesis of the putative neurotransmitter pool of glutamate. When cerebellar of hippocampal neurons were treated with QA, it elevated the specific activity of glutaminase in a dose-dependent manner. The half-maximal effect was obtained at about 0.1 μM, the maximum increase was at about 1 μM, but levels higher than 10 μM QA produced progressive reduction in glutaminase activity. In contrast, QA had little effects on the activities of lactate dehydrogenase and aspartate aminotransferase and the amount of protein, indicating that the increase in glutaminase was relatively specific. The QA-mediated increase in glutaminase was mimicked by the ionotropic QA receptor agonist -amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA; EC50, about 0.5 μM), but not by the metabotropic QA receptor agonist trans-(±)-1-aino-cyclopentyl-1,3,dicarboxyalte (t-ACPD; up to 0.5 mM). The specific ionotropic QA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) inhibited QA- and AMPA-mediated increases in glutaminase activity in a dose-dependent manner, whereas other glutamate receptor antagonists, -2-amino-5-phosphonovalerate, γ- -glutamyl aminomethyl sulphonic acid and γ- -glutamyl diethyl ester were ineffective. The elevation of neurotransmitter enzyme was Ca2+-dependent. The increase in Ca2+ influx essentially through the activation of L-type voltage-operated Ca2+ channels, and not the mobilization of internal Ca2+ stores, was responsible for these QA receptor-mediated long-term plastic changes in hippocampal and cerebellar neurons.  相似文献   
26.
27.
We present our experience with twenty children with insulin dependent diabetes mellitus admitted during the past 2 1/2 years. Sixteen patients were admited with acute onset of ketoacidosis while four were having gradual onset. Active and symptomatic treatment was started in all diabetic ketoacidotic patients. One patient died during the acute stage. Eleven patients were followed for 3–6 months or more. Glycosylated hemoglobin was considered as a criteria for control. Three had good control, two fair and six poor control; six developed diabetic ketoacidosis and three developed hypoglycemia  相似文献   
28.
29.
30.
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