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   1233篇
  免费   121篇
  国内免费   30篇
耳鼻咽喉   3篇
儿科学   59篇
妇产科学   9篇
基础医学   152篇
口腔科学   66篇
临床医学   120篇
内科学   231篇
皮肤病学   27篇
神经病学   35篇
特种医学   236篇
外科学   82篇
综合类   83篇
预防医学   105篇
眼科学   12篇
药学   62篇
中国医学   23篇
肿瘤学   79篇
  2023年   8篇
  2022年   23篇
  2021年   24篇
  2020年   15篇
  2019年   17篇
  2018年   19篇
  2017年   26篇
  2016年   19篇
  2015年   36篇
  2014年   35篇
  2013年   29篇
  2012年   24篇
  2011年   44篇
  2010年   30篇
  2009年   36篇
  2008年   35篇
  2007年   28篇
  2006年   27篇
  2005年   25篇
  2004年   21篇
  2003年   23篇
  2002年   17篇
  2001年   24篇
  2000年   24篇
  1999年   22篇
  1998年   48篇
  1997年   53篇
  1996年   48篇
  1995年   43篇
  1994年   28篇
  1993年   37篇
  1992年   31篇
  1991年   29篇
  1990年   21篇
  1989年   27篇
  1988年   41篇
  1987年   52篇
  1986年   39篇
  1985年   18篇
  1984年   13篇
  1983年   15篇
  1982年   18篇
  1981年   23篇
  1980年   21篇
  1979年   11篇
  1978年   13篇
  1977年   15篇
  1976年   26篇
  1975年   11篇
  1969年   5篇
排序方式: 共有1384条查询结果,搜索用时 15 毫秒
71.
72.
Clark  LJ; Chan  LS; Powars  DR; Baker  RF 《Blood》1981,57(4):675-678
Negative charges on the external surface of red cells were visualized by colloidal iron hydroxide labelling of 50% of the membrane area after osmotic hemolysis and glutaraldehyde fixation. Counts were made over randomly selected areas on electron micrographs at 350,000 x magnification. Statistical analyses showed that at the 95% level of confidence there was no significant difference between oxygenated normal (AA) and sickle (SS) cells in either the distribution or the density of negative charges.  相似文献   
73.
Pulmonary lymphangitic spread of carcinoma: appearance on CT scans   总被引:6,自引:0,他引:6  
Stein  MG; Mayo  J; Muller  N; Aberle  DR; Webb  WR; Gamsu  G 《Radiology》1987,162(2):371-375
Chest computed tomography (CT), including high-resolution CT with thin (1.5-mm) sections was used to evaluate proved (pathologically or clinically) lymphangitic spread (LS) of tumor in 12 patients. These appearances were compared with thin-section scans obtained in 11 healthy subjects. Thin-section CT demonstrated findings consistent with thickening of the normal lung interstitium. In all patients, thin sections showed an increase in the number of peripheral lines (1-2 cm in length) that were diffuse in generalized disease and localized in focal disease. Normal peripheral arcades were not increased in number, but the limbs forming the arcades were thickened in all patients. A diffuse increase in linear and curvilinear structures (reticular pattern) was seen toward the center of the lung. Polygonal structures 1-2 cm in diameter were seen in seven patients with LS but not in healthy subjects. Fissures were thickened in nine patients. Selected 1.5-mm-thick CT sections are recommended through abnormal areas (seen at CT or on chest radiographs) or if these are normal at three levels (midapex, hilus, and 3 cm above the diaphragm) when scanning patients with tumors known to cause LS.  相似文献   
74.
In the present study, novel ester derivatives of CAPE were designed and synthesized as neuroprotective agents. The anti-inflammatory and antioxidant activities of these compounds were evaluated at the cellular level, while the blood-brain barrier (BBB) permeability was predicted by parallel artificial membrane permeability assay (PAMPA). The results revealed that phenolic hydroxyl groups and double bonds in the structure of CAPE had important effects on neuroprotective activities. Accordingly,a preliminary structure-activity relationship was summarized in this paper. In addition, we observed a significant improvement on BBB permeability. These results provided important references for the structural modification and optimization of CAPE in the future.  相似文献   
75.
Malnutrition, either actually malnourished or at risk, is present in 80% of the elderly population presenting to hospital for admission. Although many factors contribute to this situation, one yet to be explored is malabsorption. We therefore aimed to assess nutritional status as well as the prevalence of altered mucosal permeability and celiac disease among a group of elderly patients presenting for rehabilitation. Forty-eight subjects were recruited (16 females) with a mean age of 83.7 (SD 6.1), body mass index 21.8 kg/m2 (SD 3.9), mini-nutritional assessment (MNA) 19.5 (SD 3.4). They had no current gastrointestinal symptoms and undertook an assessment of mucosal permeability using the dual sugar absorption test of lactulose (7.5 g) and rhamnose (1 g). Ten of the 48 subjects had increased mucosal permeability with an L:R ration ranging from 0.0860 to 7.706 (N 0.01–0.08). These subjects were all at risk or malnourished according to the MNA score and they had a significantly lower mean MNA score of 17.2 (SD 3.5) compared to normal absorbers with a mean of 19.5 (SD 3.4). Two of the subjects had positive tissue trans-glutaminase antibodies. The higher risk of potential malabsorption in this elderly population has significant implications both for nutritional supplementation and for drug absorption as well as being a possible major contributor to malnutrition.  相似文献   
76.
An epidemic of St. Louis encephalitis in 1985 in Mesa County, Colorado, led to 17 cases, including one fatality. Risk was associated with advanced age and residence in Grand Junction, the county's principal city. A trend was observed toward higher risk in females. However, increased risk in females was not associated with higher infection rates (increased exposure). Capture enzyme immunoassays detected specific immunoglobulin M (IgM) and immunoglobulin A after infection. A serosurvey of Grand Junction residents disclosed an infection rate of 4.0%, indicating that 1,123 epidemic St. Louis encephalitis infections may have occurred in the city. Evidence of previous St. Louis encephalitis virus infection was found in 11.2% of survey respondents who had neutralizing antibody to the virus without specific IgM. The prevalence of St. Louis encephalitis virus antibody was similar to rates observed in serosurveys undertaken 30 years earlier, indicating that the level of endemic St. Louis encephalitis transmission in the city had not changed appreciably in that interval.  相似文献   
77.
目的:探讨活血清胰汤灌肠辅助手术治疗急性重症胰腺炎对患者AMS、UAMY、LPS水平及免疫功能的影响。方法:选取2019年3月至2020年3月陕西省宝鸡市中医医院收治的急性重症胰腺炎患者70例作为研究对象,按随机数字表法将其分为对照组和观察组,每组35例。2组均采用经内镜逆行性胰胆管造影术进行治疗,对照组术后给予常规治疗,观察组术后在对照组的基础上加用活血清胰汤灌肠治疗,2组均治疗1周。比较2组治疗1周后的临床疗效;比较2组治疗前、治疗1周后的胰腺炎标志物水平、细胞免疫指标及体液免疫指标水平。结果:治疗1周后,观察组总有效率为94.29%,高于对照组(77.14%,P<0.05)。与治疗前比较,治疗1周后,2组血清AMS、LPS、UAMY及CD8+水平均降低,且观察组低于对照组(P<0.05);2组血清CD3+、CD4+、IgG、IgM、IgA水平及CD4+/CD8+比值均升高,且观察组高于对照组(P<0.05)。结论:活血清胰汤灌肠辅助手术治疗急性重症胰腺炎,可通过降低患者血清AMS、LPS及UAMY水平,缓解炎性反应,同时可改善免疫功能,进而有助于提高疗效。  相似文献   
78.
目的:探究加味瓜蒌枳实汤联合哌拉西林钠他唑巴坦钠对痰热蕴肺型卒中相关性肺炎(SAP)患者的免疫功能和血清炎症因子水平的影响。方法:将80例痰热蕴肺型SAP患者随机分为对照组与观察组,各40例,对照组SAP患者在基础治疗上加用哌拉西林钠他唑巴坦钠,观察组患者在对照组治疗基础上加用加味瓜蒌枳实汤,连续治疗2周,并比较两组SAP患者治疗前后的临床治疗效果、免疫指标、炎症指标及肺功能情况。结果:与本组治疗前比较,两组SAP患者治疗后X射线片病灶、肺啰音、咳嗽、发热、痰色、便秘评分均明显降低(P<0.05);两组SAP患者的第1秒内用力呼气量占呼气量的比例(FEV1/FVC)、第1秒用力呼气容积百分比(FEV1%)均明显改善(P<0.05)。与对照组治疗后比较,观察组患者的FEV1/FVC、FEV1%改善更明显(P<0.05)。与本组治疗前比较,两组SAP患者经治疗后中性粒细胞与淋巴细胞比值(NLR值)均明显降低(P<0.05);与对照组治疗后比较,观察组患者的NLR值明显降低(P<0.05)。与本组治疗前比较,两组SAP患者在治疗后的血清降钙素原(PCT)、超敏C...  相似文献   
79.
Background: We determined qualitative and quantitative serum unconjugated bile acid (SUBA) levels among children with history of intestinal failure (IF) and suspected small bowel bacterial overgrowth (SBBO). Methods: This was a single‐center, case‐control pilot study conducted at Cincinnati Children's Hospital Medical Center. Children with history of IF and suspected SBBO were enrolled as subjects. Age‐matched children without IF or suspected SBBO served as controls. All participants underwent small bowel fluid sampling for microbial culture analysis. Additionally, serum fractionated and total bile acids were measured by liquid chromatography‐mass spectrometry at enrollment and following treatment for SBBO. Results: SUBA concentrations were elevated in IF subjects (median 1.16 μM, range 0.43–10.65 μM) compared with controls (median 0.10 μM, range 0.05–0.18 μM, P = 0.001). Among SUBA, chenodeoxycholic acid (CDCA) was significantly elevated in subjects (median 0.8 μM, range 0–7.08 μM) compared with controls (median 0 μM, range 0–0.03 μM, P = 0.012). When controls were excluded from analysis, IF subjects with positive aspirates for SBBO demonstrated higher concentration of CDCA (median 7.36 μM, range 1.1–8.28 μM) compared with IF subjects with negative aspirates (median 0.18 μM, range 0–1.06 μM, P = 0.017). Treatment for SBBO did not alter SUBA concentration. Conclusions: SUBA concentrations are elevated in children with history of IF and presumed SBBO compared with non‐IF controls. CDCA was more prevalent in IF subjects with positive aspirates for SBBO compared with IF subjects with negative aspirates. The determination of SUBA concentration may be a useful surrogate to small bowel fluid aspiration in the diagnosis of SBBO in children with history of IF.  相似文献   
80.
目的评价沙棘提取物的抗氧化作用。方法采用老龄小鼠模型,设置老龄对照组、溶剂对照组和0.50g/kg BW、1.00g/kg BW、1.50g/kg BW沙棘提取物组,干预30 d后检测各组动物血液丙二醛(MDA)含量和谷胱甘肽过氧化物酶(GSHPX)活性,肝脏谷胱甘肽(GSH)和蛋白质羰基含量。结果与对照组比较,各剂量组10%肝匀浆中蛋白质羰基含量差异无显著性,1.50g/kg BW沙棘提取物组溶血液中MDA含量降低(P<0.05)、GSH-PX活性明显升高(P<0.05)、10%肝匀浆中GSH含量明显升高(P<0.05)。结论在本试验条件下,沙棘提取物能提高老龄小鼠的抗氧化能力。  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