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   8697篇
  免费   864篇
  国内免费   10篇
耳鼻咽喉   65篇
儿科学   219篇
妇产科学   197篇
基础医学   1100篇
口腔科学   148篇
临床医学   877篇
内科学   2047篇
皮肤病学   181篇
神经病学   741篇
特种医学   256篇
外科学   1001篇
综合类   280篇
一般理论   7篇
预防医学   1104篇
眼科学   129篇
药学   494篇
中国医学   4篇
肿瘤学   721篇
  2023年   66篇
  2022年   69篇
  2021年   129篇
  2020年   97篇
  2019年   127篇
  2018年   151篇
  2017年   119篇
  2016年   118篇
  2015年   148篇
  2014年   199篇
  2013年   296篇
  2012年   414篇
  2011年   386篇
  2010年   251篇
  2009年   192篇
  2008年   356篇
  2007年   430篇
  2006年   431篇
  2005年   419篇
  2004年   395篇
  2003年   348篇
  2002年   307篇
  2001年   296篇
  2000年   291篇
  1999年   228篇
  1998年   97篇
  1997年   90篇
  1996年   71篇
  1995年   85篇
  1994年   57篇
  1993年   75篇
  1992年   228篇
  1991年   209篇
  1990年   191篇
  1989年   160篇
  1988年   188篇
  1987年   161篇
  1986年   162篇
  1985年   148篇
  1984年   97篇
  1983年   99篇
  1981年   57篇
  1979年   73篇
  1978年   84篇
  1976年   60篇
  1975年   65篇
  1974年   56篇
  1973年   99篇
  1971年   64篇
  1970年   66篇
排序方式: 共有9571条查询结果,搜索用时 16 毫秒
31.
32.
Prediction of choledocholithiasis using a pocket microcomputer   总被引:4,自引:0,他引:4  
A computerized method, using a small pocket computer, has been used to predict the presence of choledocholithiasis in a prospective series of 239 patients undergoing cholecystectomy. From an initial data base of 424 patients 36 factors were evaluated and the most important 2 of these were determined by multivariate analysis for use in the prospective analysis. Satisfactory operative cholangiograms were a prerequisite to evaluation of the statistical method and were obtained in 90.4 per cent of cases. Using the computerized method a common bile duct stone would have been overlooked in only 1 patient but 17 unnecessary explorations would have been carried out. The overall accuracy of the computerized method was 92.5 per cent. When the method was applied to a further study of 97 patients from a separate centre the overall accuracy was 85.6 per cent. If the method was used to aid selective use of operative cholangiography, cholangiograms would be performed in 20 per cent and stones would be overlooked in less than 1 per cent.  相似文献   
33.
34.
An open, randomized, cross-over study was performed to compare the efficacy and acceptability of two breath-actuated inhalers, the Turbohaler (T) and Diskhaler (D), for delivery of beta-agonists. Thirty six adults with chronic asthma requiring beta-agonists four times daily were treated with terbutaline 500 micrograms via T and salbutamol 400 micrograms via D four times daily, each period lasting four weeks. Additional bronchodilator via pressurized aerosol was permitted as required. Peak expiratory flow (PEF) was recorded in the morning (before and after beta-agonist) and in the evening. The mean morning PEF was higher during the first two weeks using T (295 l.min-1) than whilst using D (281 l.min-1, p < 0.01), but this difference did not persist during the second two weeks and there were no differences in post-bronchodilator PEF or rescue beta-agonist use. After four weeks, > 90% of patients used both inhaler devices efficiently and they were equally acceptable in terms of ease of use and convenience to carry. The Diskhaler and Turbohaler achieve similar clinical efficacy for delivery of beta-agonists.  相似文献   
35.
36.
Pellets formed from isolated bovine growth plate chondrocytes were grown in various capacitively coupled electrical fields. The signals chosen were 0, 10, 100, 250, 500, 750, 1,000, and 1,500 V peak-to-peak, 60 kHz. The effect on cell proliferation and matrix production of these different voltages was determined by [3H]thymidine and [35S]sulfate uptake, respectively, Cyclic AMP assays were done to determine if increases in either thymidine or sulfate uptake were associated with changes in cAMP levels. Significantly increased cell proliferation occurred at 500, 750, and 1,000 V peak to peak. The calculated electric fields were 1.5 to 3.0 x 10(-2) V/cm. Proliferation was significantly inhibited at 1,500 V peak-to-peak with a calculated field of 4.5 x 10(-2) V/cm. Little if any change was seen in cAMP levels at 30 or 60 min following application of the appropriate electric signals.  相似文献   
37.
Audit is now recognised as being an essential component of clinical practice. We report on the first year of the Meath Intensive Care Audit (MICA). This audit was instituted to investigate the activity of the unit, to assess the feasibility of continuous audit in our ICU and to provide data for future development of ICU facilities. Two hundred and fifty four patients were admitted between July 1st 1990 and June 30th 1991. The mean age at admission was 58 years and the mean length of stay 5.2 days. The mean APACHE II score was 16. Thirty four patients (13.4%) died in the ICU and 17 patients died in hospital following discharge from the unit bringing the hospital mortality rate to 20%. The audit proved feasible to implement and data collection is now accepted as a routine part of our ICU work.  相似文献   
38.
Many conventional dressings are painful when removed, and may be detrimental to healing. In a pilot study ten consecutive abscesses, requiring incision and drainage, were packed with a calcium alginate dressing: this was well tolerated, its removal causing minimal pain. No adverse effects were attributable to its use. A controlled trial was therefore carried out to compare calcium alginate with the more traditional saline-soaked gauze for packing abscess cavities, following incision and drainage. Patients were randomized to receive either calcium alginate (16 patients) or gauze dressing (18 patients). At the first dressing change the patient marked on a linear analogue scale the pain experienced; the nurse noted similarly the ease of removal of the dressing. Calcium alginate was significantly less painful to remove after operation (P less than 0.01), and also easier to remove (P less than 0.01) than gauze dressings. If abscess cavities are packed after incision and drainage, calcium alginate appears to be an improvement on conventional dressings.  相似文献   
39.
The combinations of ampligen and zidovudine at ratios of 100:1, 25:1, 10:1, and 1:50 acted synergistically to reduce cytopathology caused by HIV in MT-2 cell cultures. Combination indices were less than 1 at all of these ratios representing different combinations of concentrations and at 3 effective doses (ED30, ED50, ED70). Combination of drugs which show synergism at a wide range of ratios of combinations suggest that they may be useful clinically, and that the antiviral efficacy of ZDV may be increased in combination with ampligen. Synergism was also found between ampligen and zidovudine by reduction of HIV-produced plaques in a HeLa cell line expressing CD-4 receptors. However the combination of ampligen and dideoxyinosine against HIV in MT-2 cells was only additive and not synergistic.  相似文献   
40.
AIMS: Uncertainty exists as to which reperfusion strategy for ST-elevation myocardial infarction (MI) is optimal. We evaluated whether optimal pharmacologic therapy at the earliest point of care, emphasizing pre-hospital randomization and treatment was non-inferior to expeditious primary percutaneous coronary intervention (PCI). METHODS AND RESULTS: Which Early ST-elevation myocardial infarction Therapy (WEST) was a four-city Canadian, open-label, randomized, feasibility study of 304 STEMI patients (> 4 mm ST-elevation/deviation) within 6 h of symptom onset, emphasizing pre-hospital ambulance treatment and participation of community and tertiary care centres. All received aspirin, subcutaneous enoxaparin (1 mg/kg), and were randomized to one of three groups: (A) tenecteplase (TNK) and usual care, (B) TNK and mandatory invasive study < or = 24 h, including rescue PCI for reperfusion failure, and (C) primary PCI with 300 mg loading dose of clopidogrel. Time from symptom onset to treatment was rapid (to TNK for A = 113 and B = 130 min and for PCI in C = 176 min). The primary outcome, a composite of 30-day death, re-infarction, refractory ischaemia, congestive heart failure, cardiogenic shock, and major ventricular arrhythmia, was 25% (Group A), 24% (Group B), and 23% (Group C), respectively. However, there was a higher frequency of the combination of death and recurrent MI in Group A vs. Group C (13.0 vs. 4.0%, respectively, P-logrank = 0.021), yet no difference between Group B (6.7%, P-logrank = 0.378) and C. CONCLUSION: These data suggest that a contemporary pharmacologic regimen rapidly delivered, coupled with a strategy of regimented rescue and routine coronary intervention within 24 h of initial treatment, may not be different from timely expert PCI.  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