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   348篇
  免费   12篇
  国内免费   15篇
儿科学   15篇
基础医学   22篇
口腔科学   4篇
临床医学   34篇
内科学   57篇
皮肤病学   4篇
神经病学   12篇
特种医学   106篇
外科学   15篇
综合类   15篇
预防医学   10篇
眼科学   11篇
药学   25篇
中国医学   31篇
肿瘤学   14篇
  2023年   1篇
  2021年   2篇
  2020年   5篇
  2018年   3篇
  2016年   4篇
  2015年   3篇
  2014年   8篇
  2013年   10篇
  2012年   2篇
  2011年   7篇
  2010年   14篇
  2009年   10篇
  2008年   7篇
  2007年   17篇
  2006年   18篇
  2005年   12篇
  2004年   14篇
  2003年   4篇
  2002年   1篇
  2001年   8篇
  2000年   2篇
  1999年   7篇
  1998年   21篇
  1997年   19篇
  1996年   27篇
  1995年   14篇
  1994年   6篇
  1993年   6篇
  1992年   3篇
  1991年   3篇
  1990年   3篇
  1989年   13篇
  1988年   22篇
  1987年   9篇
  1986年   9篇
  1985年   14篇
  1984年   6篇
  1983年   6篇
  1982年   4篇
  1981年   8篇
  1980年   4篇
  1979年   1篇
  1978年   1篇
  1977年   7篇
  1976年   7篇
  1975年   3篇
排序方式: 共有375条查询结果,搜索用时 15 毫秒
81.
Introduction:  Temporary GES (tempGES) can improve both gastric emptying and symptoms in post-surgical gastroparesis (PS-GP). (SSAT 2004). Long-term effects on GI symptoms and gastric emptying are unknown. Since many PS-GP patients have non-delayed emptying, the long-term effect on baseline normal or rapid emptying is also unknown.
Patients:  36 pts (6 M, 30 F, mean age 42 years) with post-surgical: Bilroth I ( n  = 11), Bilroth II ( n  = 4), other gastric surgery ( n  = 21) disordered gastric emptying were evaluated.
Methods:  GI symptoms (vomiting = V, Total = TSS), and solid meal gastric emptying (GET) at 1 and 4 h, were compared at baseline (Base), after temporary (tempGES) and permanent (permGES) gastric electrical stimulation as previously described (NGM, 2004; 16: 635.) Long-term follow-up for permanent GES ranged from 6 month to 10 years. Results were compared by t-tests, and are reported as means ± SEM.
Results:  29 of the 36 patients were able to tolerate food for baseline quantitative gastric emptying testing. 20 patients had delayed and 9 patients had non-delayed gastric emptying, with 7/9 being rapid. With both tempGES and permGES, GI symptoms improved (p < 0.05). Both tempGES and permGES showed accelerated GET for delayed patients and generally slowed GET for non-delayed (p < 0.05 for 1 h values). See tables below.
Conclusions:  In a large group of post-surgical GP patients, temporary and permanent gastrointestinal electrical stimulation improved GI symptoms independent of gastric emptying and for a prolonged time. GES improves symptoms independent of baseline gastric emptying, and improves GET dependent on the baseline gastric emptying.
 
  相似文献   
82.
83.
OBJECTIVE: A recent case series study found that only 4.7% of 402 playgrounds in which arm fractures occurred in Victorian schools complied with the recommended 20 cm depth of tanbark. Tanbark depths at fall sites varied between 0-27 cm and the mean was 11.1 (5.0) cm. The purposes of the present study were to (1) measure impact attenuation properties of shallow and compacted depths of tanbark; (2) validate laboratory measurements with in situ data; (3) compare impact attenuation properties of compacted tanbark with an Australian manufactured rubber based surface material; and (4) study the impact performance of rubber and tanbark hybrid surfacing. METHODS: A standard test headform was dropped on tanbark and rubber surfaces in a laboratory setting to measure peak impact deceleration and head injury criterion (HIC) values. Variations in surface depth ranged from 2 cm-20 cm (tanbark) and 2 cm-9 cm (rubber). Drop height ranged from 0.5 m-2.5 m. RESULTS: Peak deceleration and HIC increased with increasing drop height and decreasing surface depth. Laboratory measurements at depths less than 8 cm overestimated peak deceleration and HIC values compared with in situ playground measurements. Impact attenuation of a 9 cm thick bilaminate rubber material was comparable to that of an 18 cm depth of compacted tanbark. Rubber-tanbark hybrid surfaces showed improved impact attenuation over individual surfaces. CONCLUSIONS: Compacted tanbark of depth less than 8 cm is ineffective in attenuating playground falls, resulting in excessive impact deceleration and HIC values. Shallow and compacted tanbark found in many Victorian school playgrounds poses a high risk for severe head injury. This calls for stricter enforcement of playground surface depth compliance.  相似文献   
84.
Bioassay-guided fractionation of an MeCOEt extract of Frullania nisquallensis Sull. has furnished a DNA-damaging sesquiterpene, costunolide (1), and two inactive compounds, a sesquiterpene (-)-frullanolide (2) and a tridepside tenuiorin (3). (13)C-NMR data of 3 are reported.  相似文献   
85.
AIM:To isolate and characterize solid tumor inhibitory and other constituents from a bioactive extract of Casimiroa tetrameria((Rutaceae).METHODS:A crude extract of C.tetrameria obtained from the US National Cancer Institute Natural Product Repository and found to exhibit selective toxicity to solid tumor cells was subjected bioactivity-guided fractionation involving solvent-solvent partitioning,gel filtration,and chromatography.The structures of all isolated compounds were elucidated by spectroscopic analy...  相似文献   
86.
This study investigates the in vivo dose response profiles of the target enzyme cholinesterase (ChE) and the detoxifying enzymes carboxylesterase (CaE) in the fetal and maternal compartments of pregnant rats dosed with chlorpyrifos [(O,O'-diethyl O-3,5,6-trichloro- 2-pyridyl) phosphorothionate], a commonly used organophosphorus insecticide. Pregnant rats were dosed daily (po) with chlorpyrifos in corn oil (0, 3, 5, 7, or 10 mg/kg) on gestational days (GD) 14-18. Animals were sacrificed 5 h after the last chlorpyrifos dose (time of maximum brain cholinesterase inhibition) for analysis of ChE and CaE activity in maternal blood, liver, brain, placenta, and fetal liver and brain. The in vitro sensitivity (i.e., IC50, 30 min, 26 degrees C) of CaE also was determined by assaying the activity remaining after incubation with a range of chlorpyrifos-oxon concentrations. In vivo exposure to 10 mg/kg chlorpyrifos from GD14-18 caused overt maternal toxicity, with dose-related decreases in ChE activity more notable in maternal brain than fetal brain. Dose-related effects were also seen with chlorpyrifos-induced inhibition of fetal liver ChE and maternal brain CaE activities. Gestational exposure caused no inhibition of placental ChE or CaE, fetal brain CaE, or maternal blood CaE. ChE activities in the maternal blood and liver, as well as fetal and maternal liver CaE, however, were maximally inhibited by even the lowest dosage of chlorpyrifos. The in vitro sensitivity profiles of CaE to chlorpyrifos-oxon inhibition were valuable in predicting and verifying the in vivo CaE response profiles. Both the in vivo and in vitro findings indicated that fetal liver CaE inhibition was an extremely sensitive indicator of fetal chlorpyrifos exposure.   相似文献   
87.
The effectiveness of a eutectic mixture lidocaine-prilocaine topical anaesthetic cream (EMLA) patch compared with a placebo patch in the reduction of pain associated with intramuscular immunization was evaluated. As part of the study, 161 children (aged 4-6-y) undergoing routine diphtheria, pertussis, tetanus and polio (DPTP) immunization in five urban and five rural private office settings were randomly assigned to an EMLA patch (n = 83) or a placebo patch control group (n = 78). Pain measurements included: child's self-report on a Faces Pain Scale; facial action on the Child Facial Coding System; the Children's Hospital of Eastern Ontario Pain Scale and parent and technician ratings on a Visual Analogue Scale. Parents also rated their own and their child's immunization-related anxiety on a Visual Analogue Scale. The EMLA patch group had significantly less pain on all four pain measures compared with the placebo group. Of the children in the placebo group, 43% had clinically significant pain, compared with 17% of children in the EMLA patch group. No severe adverse symptoms occurred as a result of either EMLA or placebo patch application. CONCLUSION: The EMLA patch reduced immunization pain in 4 to 6-y-old children during needle injection.  相似文献   
88.
89.
Magnetic resonance (MR) imaging has given mixed results in the detection of renal masses. To identify the reasons for this and to determine the optimal pulse sequences for evaluating renal tumors, the authors imaged 12 primary renal tumors in vivo and 17 in vitro at 0.35 T. Histopathologic findings for each specimen were closely correlated with the MR images. Four of seven solid tumors imaged in vivo were isointense with surrounding normal renal parenchyma at all pulse sequences. The other three tumors were hyperintense in vivo at T2-weighted sequences. At heavily T2-weighted sequences eight solid tumors were hyperintense in vitro and four were hypointense. There was no correlation between signal intensity and specific tissue type or histologic pattern for solid tumors. The five cystic tumors were well seen both in vivo and in vitro on T2-weighted images. However, the signal intensity of the cyst fluid was an unreliable indicator of benignancy. SE MR imaging at 0.35 T has significant limitations in the detection of solid renal masses.  相似文献   
90.
Contrast correction is often required in digital subtraction radiography when comparing medical data acquired over different time periods owing to dissimilarities in the acquisition process. This paper focuses on dental radiographs and introduces a novel approach for correcting the contrast in dental image pairs.The proposed method modifies the subject images by applying typical registration techniques on their histograms. The proposed histogram registration method reshapes the histograms of the two subject images in such a way that these images are matched in terms of their contrast deviation. The method was extensively tested over 4 sets of dental images, consisting of 72 registered dental image pairs with unknown contrast differences as well as 20 dental pairs with known contrast differences. The proposed method was directly compared against the well-known histogram-based contrast correction method.The two methods were qualitatively and quantitatively evaluated for all 92 available dental image pairs. The two methods were compared in terms of the contrast root mean square difference between the reference image and the corrected image in each case. The obtained results were also verified statistically using appropriate t-tests in each set.The proposed method exhibited superior performance compared with the well-established method, in terms of the contrast root mean square difference between the reference and the corrected images. After suitable statistical analysis, it was deduced that the performance advantage of the proposed approach was statistically significant.  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