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   357篇
  免费   17篇
  国内免费   51篇
儿科学   13篇
基础医学   19篇
口腔科学   11篇
临床医学   83篇
内科学   95篇
皮肤病学   3篇
神经病学   2篇
特种医学   83篇
外科学   17篇
综合类   22篇
预防医学   16篇
眼科学   6篇
药学   37篇
肿瘤学   18篇
  2022年   1篇
  2021年   4篇
  2020年   2篇
  2019年   3篇
  2018年   1篇
  2017年   6篇
  2016年   12篇
  2015年   7篇
  2014年   11篇
  2013年   10篇
  2012年   2篇
  2011年   5篇
  2010年   11篇
  2009年   7篇
  2008年   7篇
  2007年   30篇
  2006年   4篇
  2005年   8篇
  2004年   4篇
  2003年   2篇
  2002年   6篇
  2001年   11篇
  2000年   6篇
  1999年   10篇
  1998年   26篇
  1997年   29篇
  1996年   16篇
  1995年   22篇
  1994年   13篇
  1993年   16篇
  1992年   4篇
  1991年   9篇
  1990年   5篇
  1989年   13篇
  1988年   13篇
  1987年   7篇
  1986年   12篇
  1985年   11篇
  1984年   10篇
  1983年   1篇
  1982年   7篇
  1981年   7篇
  1980年   5篇
  1979年   6篇
  1977年   7篇
  1976年   8篇
  1975年   4篇
  1970年   1篇
  1968年   1篇
  1966年   1篇
排序方式: 共有425条查询结果,搜索用时 15 毫秒
101.
BACKGROUND: Multiple Acyl-CoA-Dehydrogenase deficiency (MADD) is an inherited metabolic disorder characterized by impaired oxidation of fatty acids and some amino acids. METHODS: We were interested whether children with MADD could tolerate a prolonged low-intensity exercise test and if this test could have any additional diagnostic value. Therefore, we performed a maximal exercise test and a low-intensity prolonged exercise test in 2 patients with MADD and in 5 control subjects. During a prolonged exercise test the subjects exercised on a cycle ergometer at a constant workload of 30% of their maximum for 90 minutes and heart rate, oxygen uptake, fuel utilization and changes in relevant blood and urinary parameters were monitored. RESULTS: The tests were tolerated well. During the prolonged exercise test the fatty acid oxidation (FAO) was quite low compared to 5 control subjects, while characteristic metabolites of MADD appeared in plasma and urine. CONCLUSION: We suggest that the prolonged exercise test could be of diagnostic importance and might replace the fasting test as a diagnostic procedure in some cases, particularly in patients with anamnestic signs of intolerance for prolonged exercise.  相似文献   
102.
王瑞  樊颖  关华欣  杨为红  吕洪波 《医学争鸣》2005,26(24):2276-2276
1临床资料2003-10/2004-12住院老年多器官功能衰竭患者46例,全部为男性,年龄(79±5)岁.2个器官功能衰竭为A组15例,年龄(77±6)岁;3个以上器官功能衰竭为B组20例,年龄(79±7)岁;死亡为C组11例,年龄(78±4)岁;无重要脏器功能衰竭的老年患者20例为对照组,年龄(78±6)岁,全部为男性.以上受试对象均无甲状腺疾病病史,未用影响甲状腺功能的药物.清晨空腹安静状态下抽取静脉血2mL用放免法测定TT3,TT4,FT3,FT4及TSH,药盒由天津DPC公司提供.ABC3组TT3(nmol/L)和FT3(pmol/L)水平均减低,C组减低最明显,分别为1.7±0.4和3.9±0.9,1.3±0.4和…  相似文献   
103.
木犀草素的半合成   总被引:14,自引:0,他引:14  
目的:半合成具有止咳,祛痰及消炎作用的木犀草素。方法:从陈皮中提取橙皮苷,橙皮苷再经水解,脱甲基,脱氢三步合成木犀草素。结果:三步总收率为45.9%,同时还以产好收率合成了双氢黄酮化合物:橙皮素2和圣草酚3。结论:该工艺原料易得,工艺简单,收率高。  相似文献   
104.
A 5-year territory-wide retrospective survey of invasive Haemophilus influenzae type b diseases was conducted in Hong Kong. Between 1986 and 1990, 57 cases (28 male) were recorded in children less than 12 years old (37 cases of meningitis, 9 of septicaemia and 11 of bacteraemic pneumonia). The annual incidence for children less than 5 years old was 2.7 per 105 (95% confidence interval (CI) 2.0–3.5). Of the 57 cases, 39 were Chinese and 18 non-Chinese (7 Vietnamese refugees, 6 Caucasians, 5 others). The annual incidence in Vietnamese refugees less than 5 years old was 42.7 per 105 (95% CI 17.2–87.9), giving a relative risk of 18.5 (95% CI 8.3–41.0). Chinese patients (68%) were under-represented as Chinese accounted for at least 94% of the population. Moreover, 14 of the 39 Chinese patients had pre-existing medical problems, compared with only 1 of the 18 non-Chinese patients (p = 0.022).  相似文献   
105.
There is concern that our reproductive systems are exposed to environmental hazards. A number of potential monitors of these hazards have been proposed (reported rates of cryptorchidism, testicular cancer, hypospadias, dizygotic twinning, sperm count, ectopic pregnancy and sex ratios). To discover whether these are monitoring the same hazards, secular movements in these measures are considered here. It is suggested that the secular movements of cryptorchidism and hypospadias are insufficiently reliable to give guidance on the movements of such hazards as cause them. With one possible exception, rates have not moved in parallel and so, in general, they are not monitoring the same hazards. The exception is dizygotic twinning rates and sperm counts which may have a lagged correlation. If this is true, it may be important and throw light on the hitherto unexplained movements of both. The hazards themselves are largely unidentified, but may be presumed to include: (i) the well-publicized rise in environmental oestrogens; (ii) an increasing number of women with suboptimal oestrogens (because of dieting and arduous exercise); and (iii) hormonal consequences of these two opposing trends, e.g. an increasing number of women with suboptimal androgens (possibly accounting for the increasing rates of cryptorchidism and testicular cancer).   相似文献   
106.
OBJECTIVE: Results from previous studies have shown that pre- and perinatal exposure to lead enhances susceptibility of rats to development of dental carieS. A possible explanation for this phenomenon may be that lead complexes with fluoride and renders F insoluble and unable to exert its cariostatic effects. MATERIALS AND METHODS: Thus, to explore this hypothesis, 48 desalivated Sprague-Dawley rats were placed in a König-Höfer programmed feeder and received 17 meals of powdered sucrose daily, and water ad libitum as follows: group (1) plain sucrose and sterile distilled water (SDW); (2) sucrose containing 15 ppm F and SDW; (3) sucrose containing 15 ppm F and 10 ppm Pb water; (4) sucrose containing 15 ppm F and 25 ppm Pb water. RESULTS: The highest smooth-surface, sulcal surface caries and severity scores were observed in group 1.Animals that were exposed to fluoride showed reduced smooth-surface caries and severity scores.S. sobrinus counts did not differ among the groups. CONCLUSION: Lead did not interfere with the protective effect of fluoride in the conditions of the present study.  相似文献   
107.
目的 探讨地塞米松与三磷酸腺苷(ATP)联用在体外诱导细粒棘球绦虫原头节细胞凋亡的作用。 方法 体外培养细粒棘球绦虫原头节,分别设地塞米松(5 mmol/L)组、 ATP(1.6 mmol/L)组、 地塞米松(5 mmol/L)+ATP(1.6 mmol/L)组和空白对照组,显微镜下观察原头节变化。药物诱导8 h后,选取原头节形态改变最明显的一组和空白对照组,透射电镜观察这两组原头节的超微结构,原位末端脱氧核糖核苷酸转移酶标记技术(TUNEL法)检测原头节中的凋亡细胞,半胱氨酸天冬氨酸蛋白酶-3(caspase-3)活性检测试剂盒检测该酶活性,琼脂糖凝胶电泳检测两组原头节的DNA片段。 结果 药物诱导8 h后观察,与对照组相比,地塞米松组和地塞米松+ATP组的原头节均出现团缩、顶突内凹和体积缩小,钙颗粒明显减少且模糊不清,未见原头节活动,其中地塞米松+ATP组原头节的形态改变更明显,故选择该组作为实验组,与空白对照组进行后续试验。透射电镜观察见实验组原头节中实质细胞体积缩小、细胞膜皱缩、细胞基质浓缩、核异染色质凝集呈团块状或新月形边集于核膜下,表现出凋亡细胞的特征。TUNEL法在实验组的原头节中检测到散在的凋亡细胞,对照组则未见凋亡细胞。实验组caspase-3活性约为对照组的12倍。电泳结果显示,实验组DNA中有约150 bp的核小体DNA片段。 结论 地塞米松与ATP联用可在体外诱导细粒棘球绦虫原头节细胞凋亡。  相似文献   
108.
We performed 32 overpressure radionuclide cisternography (ORNC) studies to examine 26 patients who were clinically suspected of having cerebrospinal fluid (CSF) fistula with rhinorrhea. Fifteen (47%) of these cisternography studies were positive, and the site of the leak was identified. No leak could be demonstrated in the other 17. Of 23 examinations performed in patients who had clinically documented CSF rhinorrhea, 15 (65%) were scintigraphically positive. The rapid cephalad transit of the radionuclide bolus allowed completion of the study within 30 to 45 minutes. Seven examinations were also performed with overpressure metrizamide CT cisternography (OMCTC), and five demonstrated concordant results with the radionuclide study. Patient discomfort and side effects were minimal. We conclude that radionuclide infusion cisternography is a safe, rapid, and accurate method of investigating a suspected or proven CSF rhinorrhea and that it is complementary to metrizamide cisternography.  相似文献   
109.
Eusek  JF; Bush  WH; Burnett  LL; Gibbons  RP 《Radiology》1986,158(3):850-851
Extracorporeal shock wave lithotripsy (ESWL) is now the preferred method for treating most renal calculi. We designed a cassette and grid holder and a technique for filming in the water bath. The excellent film quality permits initial localization of small or faint calculi and confirmation of satisfactory fragmentation during ESWL. The technique facilitates patient treatment and throughput and should reduce the repeat treatment rate.  相似文献   
110.

Background  

Smoking in pregnancy remains a public health challenge. Nicotine replacement therapy (NRT) is effective for smoking cessation in non-pregnant people, but because women metabolise nicotine and cotinine much faster in pregnancy, it is unclear whether this will be effective for smoking cessation in pregnancy. The NHS Health Technology Assessment Programme (HTA)-funded smoking, nicotine and pregnancy (SNAP) trial will investigate whether or not nicotine replacement therapy (NRT) is effective, cost-effective and safe when used for smoking cessation by pregnant women.  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