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   28531篇
  免费   2045篇
  国内免费   108篇
耳鼻咽喉   448篇
儿科学   1027篇
妇产科学   452篇
基础医学   2817篇
口腔科学   671篇
临床医学   2673篇
内科学   6442篇
皮肤病学   613篇
神经病学   1504篇
特种医学   1225篇
外国民族医学   1篇
外科学   5569篇
综合类   398篇
一般理论   16篇
预防医学   1463篇
眼科学   928篇
药学   2345篇
中国医学   65篇
肿瘤学   2027篇
  2024年   69篇
  2023年   258篇
  2022年   492篇
  2021年   1155篇
  2020年   566篇
  2019年   954篇
  2018年   1147篇
  2017年   728篇
  2016年   781篇
  2015年   796篇
  2014年   1281篇
  2013年   1457篇
  2012年   2173篇
  2011年   2184篇
  2010年   1124篇
  2009年   1003篇
  2008年   1596篇
  2007年   1515篇
  2006年   1430篇
  2005年   1203篇
  2004年   1118篇
  2003年   951篇
  2002年   861篇
  2001年   616篇
  2000年   563篇
  1999年   512篇
  1998年   189篇
  1997年   163篇
  1996年   161篇
  1995年   159篇
  1994年   129篇
  1993年   110篇
  1992年   276篇
  1991年   291篇
  1990年   256篇
  1989年   218篇
  1988年   215篇
  1987年   222篇
  1986年   194篇
  1985年   184篇
  1984年   117篇
  1983年   129篇
  1982年   91篇
  1981年   75篇
  1980年   69篇
  1979年   132篇
  1978年   78篇
  1977年   74篇
  1974年   69篇
  1973年   89篇
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
21.
We describe the types of aggressive behaviour and determine their prevalence in a sample of hospitalized elderly psychiatric patients. Data were obtained by nurse ratings of aggressive behaviour using the recently developed Rating Scale for Aggressive Behaviour in the Elderly; 90 patients were rated over a 3-d period. Nearly half the sample were at least mildly aggressive; the frequencies of some specific types of aggressive behaviour were high. In contrast, the frequency of injuries and the use of restraints and medication for aggressive behaviour were low. Some correlates of the aggressive behaviour were also analysed.  相似文献   
22.
23.
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   
24.
25.
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   
26.
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   
27.
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   
28.
29.
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   
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