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   3066篇
  免费   318篇
  国内免费   18篇
耳鼻咽喉   19篇
儿科学   113篇
妇产科学   25篇
基础医学   342篇
口腔科学   70篇
临床医学   253篇
内科学   484篇
皮肤病学   71篇
神经病学   182篇
特种医学   172篇
外科学   398篇
综合类   186篇
预防医学   558篇
眼科学   99篇
药学   230篇
中国医学   57篇
肿瘤学   143篇
  2023年   13篇
  2022年   24篇
  2021年   53篇
  2020年   30篇
  2019年   49篇
  2018年   53篇
  2017年   45篇
  2016年   42篇
  2015年   67篇
  2014年   93篇
  2013年   98篇
  2012年   161篇
  2011年   172篇
  2010年   119篇
  2009年   118篇
  2008年   119篇
  2007年   145篇
  2006年   125篇
  2005年   140篇
  2004年   116篇
  2003年   99篇
  2002年   97篇
  2001年   77篇
  2000年   99篇
  1999年   89篇
  1998年   83篇
  1997年   72篇
  1996年   72篇
  1995年   63篇
  1994年   58篇
  1993年   60篇
  1992年   64篇
  1991年   46篇
  1990年   53篇
  1989年   69篇
  1988年   49篇
  1987年   57篇
  1986年   43篇
  1985年   43篇
  1984年   27篇
  1983年   21篇
  1982年   18篇
  1981年   20篇
  1980年   21篇
  1979年   28篇
  1978年   14篇
  1977年   15篇
  1976年   13篇
  1972年   16篇
  1971年   12篇
排序方式: 共有3402条查询结果,搜索用时 15 毫秒
1.
2.
BACKGROUND: The anti-smoking stance taken by Adolf Hitler, coupled with Nazi support for research on smoking and lung cancer and campaigns to discourage smoking, have encouraged pro-smoking groups to equate tobacco control activities with totalitarianism. Previous work has described the situation in Germany. OBJECTIVE: To examine the situation in Austria, also part of the Reich after 1938. DESIGN: Iterative analysis of documents and reports about the situation in Austria in the 1930s and 1940s, supplemented by a review of Reich legal ordinances, party newspapers, health behaviour guidelines issued by Nazi party organisations and interviews with expert informants. RESULTS: In contrast to the situation in Germany where, albeit to a much lesser degree than is commonly believed, some anti-smoking policies were adopted, the Nazi authorities in Austria made almost no attempt to discourage smoking and the Austrian tobacco company worked closely with the Nazi authorities to ensure that supplies were maintained. CONCLUSION: Especially when looked at in the Austrian context, the much-cited link between anti-smoking policies and Nazism is a gross over-simplification. This purported link should not be used to justify the continued failure to act effectively against smoking in Germany and Austria.  相似文献   
3.
4.
Suppurative corneal ulceration in Bangladesh   总被引:8,自引:0,他引:8  
Suppurative keratitis is an important preventable cause of blindness, particularly in the developing world. This study analyses 142 cases of suppurative keratitis referred to Chittagong Eye Infirmary, Bangladesh. Some 53.5% of cases were bacterial and 35.9% were fungal. The five most common pathogens were: Pseudomonas sp. 24%, Streptococcus pneumoniae 17%, Aspergillus sp. 13%, Fusarium sp. 7% and Curvularia sp. 6%. Gram stain and culture results were consistent in 62.6% of cases. Previous antibiotic treatment was a significant factor for failure of culture isolation and less so for Gram stain failure. On Gram stain, 55.9% of pseudomonal cases were missed, but only 2% of fungal cases were missed. Over all, Gram stain had a sensitivity of 62% and positive predictive value of 84% for bacterial cases, and 98% and 94% for fungal cases, respectively. Fungal ulcers were typically filamentous, but an antecedent history of trauma was not common. The most frequent injury was due to rice grains, but the inoculum appeared to be introduced during eye washing with contaminated water. Pseudomonal ulcers occurred most frequently in the monsoon season, and Fusarium cases were seen only in the hot, dry season.  相似文献   
5.
6.
7.
8.
9.
Kuross  SA; Hebbel  RP 《Blood》1988,72(4):1278-1285
Previous studies documented the abnormal association of heme and heme proteins with the sickle RBC membrane. We have now examined RBC ghosts and inside-out membranes (IOM) for the presence of nonheme iron as detected by its formation of a colored complex with ferrozine. Sickle ghosts have 33.8 +/- 18.2 nmol nonheme iron/mg membrane protein, and sickle IOM have 4.3 +/- 3.0 nmol/mg. In contrast, normal RBC ghosts and IOM have no detectable nonheme iron. The combination of heme and nonheme iron in sickle IOM averages nine times the amount of membrane- associated iron in normal IOM. Kinetics of the ferrozine reaction show that some of this nonheme iron on IOM reacts slowly and is probably in the form of ferritin, but most (72% +/- 18%) reacts rapidly and is in the form of some other biologic chelate. The latter iron compartment is removed by deferoxamine and by treatment of IOM with phospholipase D, which suggests that it represents an abnormal association of iron with polar head groups of aminophospholipids. The biologic feasibility of such a chelate was demonstrated by using an admixture of iron with model liposomes. Even in the presence of tenfold excess adenosine diphosphate, iron partitions readily into phosphatidylserine liposomes; there is no detectable association with phosphatidylcholine liposomes. To examine the bioavailability of membrane iron, we admixed membranes and t-butylhydroperoxide and found that sickle membranes show a tenfold greater peroxidation response than do normal membranes. This is not due simply to a deficiency of vitamin E, and this is profoundly inhibited by deferoxamine. Thus, while thiol oxidation in sickle membranes previously was shown to correlate with heme iron, the present data suggest that lipid peroxidation is related to nonheme iron. In control studies, we did not find this pathologic association of nonferritin, nonheme iron with IOM prepared from sickle trait, high-reticulocyte, postsplenectomy, or iron-overloaded individuals. These data provide additional support for the concept that iron decompartmentalization is a characteristic of sickle RBCs.  相似文献   
10.
Mortality league tables: do they inform or mislead?   总被引:3,自引:0,他引:3       下载免费PDF全文
OBJECTIVE--To examine certain methodological issues related to the publication of mortality league tables, with particular reference to severity adjustment and sample size. DESIGN--Retrospective analysis of inpatient hospital records. SETTING--22 hospitals in North West Thames health region for the fiscal year 1992-3. SUBJECTS--All admissions with a principal diagnosis of aortic aneurysm, carcinoma of the colon, cervical cancer, cholecystectomy, fractured neck of femur, head injury, ischaemic heart disease, and peptic ulcer. MAIN MEASURES--In hospital mortality rates adjusted by disease severity and calculated on the basis of both admissions and episodes. RESULTS--The numbers of deaths from specific conditions were often small and the corresponding confidence intervals wide. Rankings of hospitals by death rate are sensitive to adjustment for severity of disease. There are some differences that cannot be explained using routine data. CONCLUSIONS--Comparison of crude death rates may be misleading. Some adjustment for differences in severity is possible, but current systems are unsatisfactory. Differences in death rates should be studied, but because of the scope for manipulating data, this should be undertaken in a collaborative rather than a confrontational way. Any decision to publish league tables of death rates will be on political rather than scientific grounds.  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