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   15463篇
  免费   1306篇
  国内免费   28篇
耳鼻咽喉   138篇
儿科学   483篇
妇产科学   269篇
基础医学   2167篇
口腔科学   293篇
临床医学   1811篇
内科学   2896篇
皮肤病学   416篇
神经病学   1819篇
特种医学   501篇
外科学   1552篇
综合类   195篇
一般理论   5篇
预防医学   1409篇
眼科学   386篇
药学   1191篇
  2篇
中国医学   37篇
肿瘤学   1227篇
  2023年   88篇
  2022年   157篇
  2021年   316篇
  2020年   198篇
  2019年   322篇
  2018年   344篇
  2017年   264篇
  2016年   284篇
  2015年   327篇
  2014年   418篇
  2013年   631篇
  2012年   908篇
  2011年   927篇
  2010年   537篇
  2009年   445篇
  2008年   789篇
  2007年   766篇
  2006年   790篇
  2005年   767篇
  2004年   710篇
  2003年   656篇
  2002年   621篇
  2001年   398篇
  2000年   366篇
  1999年   330篇
  1998年   144篇
  1997年   138篇
  1996年   131篇
  1995年   86篇
  1994年   105篇
  1993年   102篇
  1992年   238篇
  1991年   241篇
  1990年   246篇
  1989年   229篇
  1988年   249篇
  1987年   208篇
  1986年   219篇
  1985年   222篇
  1984年   141篇
  1983年   156篇
  1982年   100篇
  1980年   85篇
  1979年   127篇
  1978年   115篇
  1977年   84篇
  1976年   86篇
  1974年   82篇
  1973年   86篇
  1972年   91篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
This pilot study examined a behavioral treatment to increase calorie intake in toddlers with cystic fibrosis. Eight toddlers were randomly assigned to behavioral plus nutrition (BEH) or nutrition intervention (NTR) conditions. Calorie intake and weight were measured at pre- and posttreatment. The BEH group showed a trend for changes in calorie intake pre- to posttreatment (p = .07; 40% increase). Results for the BEH and NTR groups did not differ significantly. Most participants achieved weight gains consistent with normal growth. Seventy-five percent had not shown this pattern during the year prior to intervention. These results support the feasibility and potential for behavioral interventions in this age group.  相似文献   
22.
We used bromodeoxyuridine to label the earliest generated cells of the murine cerebral cortex while they were dividing, and then observed their distributions at several instances later in development. Shortly before birth, many of the labelled cells were either above the cortical plate, in the marginal zone, or below it, in the region known as the subplate in other species. These cells had disappeared by postnatal day 21.  相似文献   
23.
A diary method using household measures was employed to obtain dietary records in a large national prospective survey and a computer program, DIDO (Diet In Data Out), was designed for direct entry of the diaries. The accuracy of this computerized coding system was examined alongside that of the manual coding used for a similar diary in a previous wave, 7 years earlier, of the same survey. Accuracy was assessed by analysis of the errors in the coded and checked records by stringent re-checking of nominal 2% random subsamples of the diet diaries coded by each method. The mean time to code and check each of the 2086 7-day records in the whole survey using DIDO was 58 minutes (SD 30) compared with reported results of 1–4 hours for manual methods. The mean error rate of computerized coding and checking with DIDO was 2.3% (SD 2.1; range 0–8.9) per diary in the subsample. Correcting these mistakes made insignificant changes to the calculated mean energy and nutrient intakes for the subsample. The percentage of individuals changing to an adjacent third of nutrient distribution after correcting unambiguous errors ranged from none (for alcohol) to 11% (for carbohydrate and calcium intake). The mean error rate on a similar subsample of diaries from the earlier survey which had been coded manually was significantly higher at 5.9% (SD 4.1; range 0–17) per diary. Emphasis is laid on the importance, in coding, of dealing with ambiguities in the subjects' records, since this can affect the accuracy and the precision of the nutrient results obtained. We conclude that the DIDO coding method has the advantages of greater accuracy, speed, consistency and efficient data handling, and affords greater data accessibility for checking, compared with manual systems.  相似文献   
24.
In the gerbil maintained at euthermic (37.5 degrees C) conditions, forward masking produces a compound action potential tuning curve (CAP TC) which is less sensitive but more sharply tuned than that which is generated by simultaneous masking. These differences between forward- and simultaneously-masked CAP TCs are minimized at hypothermic (30 degrees C) conditions. The unmasking effect occurs at both temperatures, suggesting that hypothermia does not exert these changes by eliminating two-tone suppression.  相似文献   
25.
26.
Systemic sclerosis is characterised by vascular endothelial damage. Platelets adhering to the exposed subendothelium may contribute to the inflammatory changes found in the vessel wall. Increased in vitro platelet aggregability in systemic sclerosis has been reported. In vitro platelet aggregation of platelet rich plasma obtained from patients with systemic sclerosis (CREST (calcinosis, Raynaud's phenomenon oesophageal dysmotility, sclerodactyly, telangiectasia) variant) and from controls matched for age and sex was compared. Collagen, ADP, and platelet activating factor were used as aggregating agents. The actions of a platelet activating factor antagonist, BN52063, were also examined. Each agonist caused dose dependent platelet aggregation; there was no difference in either rate of primary aggregation or maximum percentage aggregation between platelets derived from patients with systemic sclerosis and from the control group (analysis of variance). BN52063 was shown to be a dose dependent, competitive antagonist of platelet aggregation induced by platelet activating factor; there was no difference in its action on platelets derived from patients with systemic sclerosis or controls. These results do not support the hypothesis that platelets from patients with systemic sclerosis are hyperactive and may explain the disappointing results obtained with antiplatelet drugs in systemic sclerosis.  相似文献   
27.
28.
Surgical staging of gastric carcinoma: sources and consequences of error   总被引:2,自引:0,他引:2  
Macroscopic 'TNM' staging was performed during 78 consecutive operations for gastric carcinoma and compared with subsequent pathological staging. Surgical assessment was correct for tumour (T) in 60 per cent when depth of invasion was assessed, for nodes (N) in 61 per cent, for liver metastases (M) in 92 per cent but for all aspects in only 21 per cent. Curability (conservatively defined as T1-3, N0-1, M0) was correct in 8 of 18 patients thus assessed at surgery and incurability was pathologically correct in 58 of 60 patients. Despite inaccurate surgical staging, no patient was denied a resection although 10 patients had unduly radical procedures for their stage and 2 had inappropriately conservative procedures for their stage (but without evidence of residual disease). Staging errors did not jeopardize conventional surgical management substantially and use of intra-operative microscopic sampling of nodes would have improved surgical treatment only minimally.  相似文献   
29.
30.
The degree of nodal involvement in a consecutive series of 400 patients with invasive ductal breast cancer is presented. A positive correlation was observed between the number of metastatic nodes identified and the number of axillary nodes examined for poorly but not moderately differentiated tumours. The relevance of this observation to breast cancer trials is discussed.  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