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   1051篇
  免费   63篇
  国内免费   15篇
耳鼻咽喉   2篇
儿科学   64篇
妇产科学   4篇
基础医学   128篇
口腔科学   18篇
临床医学   126篇
内科学   187篇
皮肤病学   23篇
神经病学   44篇
特种医学   202篇
外科学   65篇
综合类   33篇
预防医学   85篇
眼科学   15篇
药学   71篇
中国医学   2篇
肿瘤学   60篇
  2023年   2篇
  2021年   7篇
  2020年   7篇
  2019年   7篇
  2018年   17篇
  2017年   11篇
  2016年   18篇
  2015年   16篇
  2014年   25篇
  2013年   40篇
  2012年   35篇
  2011年   40篇
  2010年   31篇
  2009年   32篇
  2008年   32篇
  2007年   35篇
  2006年   31篇
  2005年   37篇
  2004年   21篇
  2003年   20篇
  2002年   22篇
  2001年   14篇
  2000年   17篇
  1999年   36篇
  1998年   43篇
  1997年   50篇
  1996年   44篇
  1995年   44篇
  1994年   26篇
  1993年   29篇
  1992年   21篇
  1991年   25篇
  1990年   19篇
  1989年   23篇
  1988年   32篇
  1987年   33篇
  1986年   22篇
  1985年   21篇
  1984年   10篇
  1983年   10篇
  1982年   18篇
  1981年   13篇
  1980年   23篇
  1979年   4篇
  1978年   12篇
  1977年   23篇
  1976年   13篇
  1975年   8篇
  1967年   2篇
  1963年   2篇
排序方式: 共有1129条查询结果,搜索用时 15 毫秒
1.
The finer branches of the biliary tree (FBBT) contain a regenerative compartment. We hypothesized that preservation of the FBBT together with its microvasculature will lead to recovery of biliary damage and prolonged preservation of bile ductules during the development of chronic liver allograft rejection. The interlobular bile ducts, portal bile ductules and extraportal biliary cells with and without microvessels were studied in sequential biopsies in five patients who fulfilled the Banff criteria of early chronic rejection (CR) (imminence group). Biopsies of CR patients (n = 12) served as controls. Biopsies were double immunostained with CD34 (microvessels) and cytokeratin 7 (biliary structures). Proliferation and proangiogenic activity were assessed with Ki67 and VEGF-A immunostaining. Severe damage of bile ducts in the imminence group did not progress to significant bile duct loss. This was associated with a high proliferative activity in all biliary structures and preservation of the microvascular compartment. VEGF-A expression was increased in all but the reperfusion biopsies. In conclusion, both regenerative activity of the FBBT and an intact microvascular compartment are associated with less damage of the biliary tree and could therefore be prerequisites for biliary regeneration.  相似文献   
2.
3.
Ethnic factors in voluntary and compulsory admissions   总被引:1,自引:0,他引:1  
Socio-demographic and clinical aspects of compulsory and informal admissions to general adult psychiatry wards over a two-year period are compared. In addition, Afro-Caribbean patients are compared with white UK-born patients. Relative rates of admission are examined. The study confirms other reports of greater than expected compulsory admissions of Afro-Caribbean patients and pays particular attention to the circumstances preceding compulsory entry to hospital and the persons and agencies involved in that process.  相似文献   
4.
Bottomley  PA; Lee  Y; Weiss  RG 《Radiology》1997,204(2):403
  相似文献   
5.
Prior studies have shown that pneumothorax is one of the more difficult entities to diagnose with digitized radiography. This study was designed to test whether increasing resolution from 1.25 to 2.5 line pairs per millimeter (lp/mm) and image processing (edge enhancement from unsharp masking) would increase accuracy and confidence in the diagnosis of pneumothorax, as well as normal cases and other forms of lung disease. Conventional radiographs were digitized with use of a laser reader and then reformatted as film hard copy. Eleven observers read 35 cases reformatted in three different ways (1.25 lp/mm, 2.5 lp/mm, 1.25 lp/mm unsharp mask). The images with finer resolution (2.5 lp/mm) and unsharp mask images were superior to those with coarser resolution (1.25 lp/mm) for the diagnosis of pneumothorax. There was no difference in diagnostic accuracy for normal patients. For abnormalities other than pneumothorax, the unsharp mask images were significantly worse. Confidence in the diagnosis of pneumothorax and other abnormalities was highest with the finest resolution (2.5 lp/mm).  相似文献   
6.
The morphological base for the impaired function of the blood retinal barrier was studied in 50 eyes of 10 insulin dependent and 21 non-insulin dependent patients with various levels of diabetic retinopathy. The permeability of the blood retinal barrier (PBRB) was determined by vitreous fluorophotometry with correction for autofluorescence, lenstransmission and non-protein bound plasma fluorescein concentration. Morphological abnormalities of diabetic retinopathy assessed by fundus photography and fluorescein angiography were individually scored on a decimal scale and related to the PBRB by multiple regression analysis. The Pbrb was not correlated to morphological abnormalities of non-proliferative retinopathy [(1) microaneurysms, (2) hard exudates, (3) soft exudates, (4) intraretinal hemorrhages, (5) fluorescein leakage, and (6) capillary closure, p > 0.3]. The PBRB was correlated to morphological abnormalities of (pre)proliferative retinopathy [(1) intraretinal microvascular abnormalities (Sirma) and (2) new vessels (Sneo): pbrb = A – B.SIRMA – C.Sneo with PBRB in nm/sec, A = 1.5 ± 0.5, B = 0.9 ± 0.2 and C = 1.7 ± 0.4, R2 = 0.65, p < 0.0001]. It can be concluded that the increased blood retinal barrier permeability in diabetic patients is mainly due to (pre)proliferative abnormalities and not to non-proliferative abnormalities.  相似文献   
7.
8.
卢日刚 《药学学报》1992,27(11):871-874
This paper provides a basic principle and experimental technique of derivative signal multiplier spectrophotometry in multicomponent mixture. A microcomputer was used to process the spectral data measured on a manual spectrophotometer (UV-7520) for the determination of moroxydine hydrochloride in Gan Mao Qing capsules. Quantitative analysis of multicomponent mixture can be done without sample separation. The selection of optimal wavelength pairs is performed through the program with a computer. The method needs no special spectrophotometer and is simple, rapid and easy to operate. The mean recovery was 99.98 +/- 0.53% (n = 12).  相似文献   
9.
BACKGROUND: Assessment of nutritional status in children with cystic fibrosis (CF) is clinically relevant. Methods to measure nutritional status should be reliable and non-invasive, and reference values should be available. AIM: To compare weight and height measurements and measurements of specific body compartments in children with CF. METHODS: In a cross-sectional survey of 58 children with CF (28 females), we compared height and weight (expressed as: weight-for-height, body mass index (BMI), height-for-age and weight-for-age) with fat mass (skinfold sum (SFS)), muscle mass (upper arm circumference (UAC)) and bioelectrical impedance analysis (BIA). Results were expressed as Z-scores, using Dutch reference values. RESULTS: BMI and weight-for-height were within the normal range (mean Z-score (range): -0.13 (-1.5, 2.7) and -0.02 (-1.7, 2.8)). Weight and height corrected for age were below normal (mean Z-score (range): -0.79 (-2.4, -0.05) and -1.2 (-2.8, 1.4) (P<0.01)). Lean body mass by skinfold sum (LBM(sfs)), UAC and BIA were also significantly below reference values (mean Z-score (range): -0.9 (-2.2, 1.8), -0.95 (-2.4, 1.8) and -1.1 (-3.6, 1.0) (P<0.01)). Lean body mass (LBM) by BIA correlated with LBM(sfs). BIA systematically underestimated LBM in both CF patients and in control subjects. CONCLUSION: Nutritional status of children with CF must be evaluated, using age-corrected weight and height expressed in Z-score. LBM estimated by SFS, UAC and by BIA appear to be useful, although longitudinal studies in CF children should be performed to evaluate their clinical significance in detecting changes in nutritional status.  相似文献   
10.
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