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   4225篇
  免费   145篇
  国内免费   21篇
耳鼻咽喉   129篇
儿科学   125篇
妇产科学   158篇
基础医学   613篇
口腔科学   16篇
临床医学   243篇
内科学   1032篇
皮肤病学   19篇
神经病学   498篇
特种医学   69篇
外科学   403篇
综合类   38篇
预防医学   209篇
眼科学   135篇
药学   449篇
中国医学   22篇
肿瘤学   233篇
  2023年   16篇
  2022年   77篇
  2021年   111篇
  2020年   44篇
  2019年   73篇
  2018年   80篇
  2017年   60篇
  2016年   60篇
  2015年   88篇
  2014年   117篇
  2013年   139篇
  2012年   272篇
  2011年   280篇
  2010年   155篇
  2009年   108篇
  2008年   253篇
  2007年   319篇
  2006年   318篇
  2005年   326篇
  2004年   353篇
  2003年   332篇
  2002年   248篇
  2001年   24篇
  2000年   20篇
  1999年   23篇
  1998年   24篇
  1997年   34篇
  1996年   24篇
  1995年   23篇
  1994年   18篇
  1993年   16篇
  1992年   21篇
  1991年   13篇
  1990年   13篇
  1989年   10篇
  1988年   11篇
  1987年   10篇
  1986年   14篇
  1985年   17篇
  1984年   26篇
  1983年   20篇
  1982年   16篇
  1981年   12篇
  1979年   10篇
  1978年   11篇
  1977年   10篇
  1975年   12篇
  1974年   12篇
  1965年   15篇
  1932年   9篇
排序方式: 共有4391条查询结果,搜索用时 15 毫秒
71.
72.
BackgroundThe remission of asthma, which is induced during specific immunotherapy (SIT) or appears spontaneously in children is not completely understood and predictors of this phenomenon are still undefined.ObjectiveTo assess CD4+CD25+Foxp3+ Treg cells and cytokine/proliferation response to allergen-specific stimulation of PBMC as predictors of steroid sparing effect of SIT and steroid dosage needs without SIT during 5 years of follow-up in asthmatic children.MethodsThis is a 5-year long study of 32 asthmatic children, sensitive only to house dust mite (HDM). Eighteen children who had completed 5 years of HDM SIT – SIT group, and 14 children without SIT as a control group were studied. All patients had baseline clinical/immunological assessment; before and after observation the minimum effective ICS dose was defined and lung function was measured.ResultsIn children from SIT group minimum effective ICS dose was reduced more than in children from control group (median reduction 65% vs. 0%; p < 0.001). Among patients in control group asthma severity was reduced after 5 years of observation in those who had at baseline higher TGF-beta1 and lower IL-13 answer to allergen stimulation of PBMC. Better response to 5 years immunotherapy was observed in those who had at baseline higher TGF-beta1 and lower proliferation answer to allergen stimulation of PBMC.ConclusionSimilar processes may decide on both, SIT-induced and spontaneously appearing, reduction in asthma severity. Immunotherapy was much more effective than pharmacotherapy in our study. IL-13 overproduction may impede reduction of disease severity in asthmatic children independently from TGF-beta pathway.  相似文献   
73.
Selenium is vital to human health. This article is a compendium of virtually all the published data on total selenium concentrations, its distribution in fruitbody, bioconcentration factors, and chemical forms in wild-grown, cultivated, and selenium-enriched mushrooms worldwide. Of the 190 species reviewed (belonging to 21 families and 56 genera), most are considered edible, and a few selected data relate to inedible mushrooms. Most of edible mushroom species examined until now are selenium-poor (< 1 μ g Se/g dry weight). The fruitbody of some species of wild-grown edible mushrooms is naturally rich in selenium; their occurrence data are reviewed, along with information on their suitability as a dietary source of selenium for humans, the impact of cooking and possible leaching out, the significance of traditional mushroom dishes, and the element's absorption rates and co-occurrence with some potentially problematic elements. The Goat's Foot (Albatrellus pes-caprae) with ~ 200 μ g Se/g dw on average (maximum up to 370 μ g/g dw) is the richest one in this element among the species surveyed. Several other representatives of the genus Albatrellus are also abundant in selenium. Of the most popular edible wild-grown mushrooms, the King Bolete (Boletus edulis) is considered abundant in selenium as well; on average, it contains ~ 20 μ g Se/g dw (maximum up to 70 μ g/g dw). Some species of the genus Boletus, such as B. pinicola, B. aereus, B. aestivalis, B. erythropus, and B. appendiculus, can also accumulate considerable amounts of selenium. Some other relatively rich sources of selenium include the European Pine Cone Lepidella (Amanita strobiliformis), which contains, on average, ~ 20 μ g Se/g dw (up to 37 μ g/g dw); the Macrolepiota spp., with an average range of ~ 5 to < 10 μ g/g dw (an exception is M. rhacodes with < 10 μ g/g dw); and the Lycoperdon spp., with an average of ~ 5 μ g Se/g dw. For several wild-grown species of the genus Agaricus, the selenium content (~ 5 μ g/g dw) is much greater than that from cultivated Champignon Mushroom; these include A. bisporus, A. bitorquis, A. campestris, A. cesarea, A. campestris, A. edulis, A. macrosporus, and A. silvaticus. A particularly rich source of selenium could be obtained from selenium-enriched mushrooms that are cultivated on a substrate fortified with selenium (as inorganic salt or selenized-yeast). The Se-enriched Champignon Mushroom could contain up to 30 or 110 μ g Se/g dw, while the Varnished Polypore (Ganoderma lucidum) could contain up to 72 μ g Se/g dw. An increasingly growing database on chemical forms of selenium of mushrooms indicates that the seleno-compounds identified in carpophore include selenocysteine, selenomethionine, Se-methylselenocysteine, selenite, and several unidentified seleno-compounds; their proportions vary widely. Some aspects of environmental selenium occurrence and human body pharmacokinetics and nutritional needs will also be briefly discussed in this review.  相似文献   
74.
75.
Background: Myocardial ischemia during coronary spasm may generate malignant ventricular arrhythmias. The J‐wave pattern was suggested to be a marker of a disorder associated with life‐threatening arrhythmias. Results: We report the case of a patient with vasospastic angina and J‐wave pattern in inferior and lateral leads associated with polymorphic ventricular tachycardia which was effectively treated only with quinidine—vasodilating drugs were not able to prevent the arrhythmia although they were effective in preventing ischemic events. Conclusion: The J‐wave pattern in inferolateral leads may be a sign of electrical vulnerability to lethal ventricular arrhythmia in patients suffering from vasospastic angina—quinidine can effectively prevent such arrhythmias in these patients.  相似文献   
76.
77.
78.
Sulfonylureas are used in treatment of diabetes. Resistance to these derivatives is a therapeutical problem. Sulfonylureas act through sulfonylurea receptor 1 (SUR1) in the beta cell. SUR1 also enhances a physiological secretion of insulin induced by an increase of glucose concentration. It may be expected that polymorphism of SUR1 gene can lead to beta cell dysfunction and resistance to sulfonylureas. The aim of this study was to examine the frequency of polymorphism in exon 22 of SUR1 gene and its correlation with type 2 diabetes mellitus and sulfonylurea treatment failure. The group consisted of 42 patients with type 2 diabetes. The controls were 46 persons with proper glucose tolerance. Polymorphism was found in 5 patients and in 1 control person. Neither statistically significant difference of polymorphism frequency nor correlation between polymorphism and sulfonylurea failure was found due to a low number of cases. Polymorphism of exon 22 of SUR1 gene appeared more frequent in diabetic than in non-diabetic subjects but this was statistically not significant.  相似文献   
79.
Uroflowmetry is the measurement of a urinary flow rate by using the flow meter. A urine flow rate is the volume of urine (millilitres) expelled from the bladder via the urethra per unit of time (second). It is expressed in ml/s.(1) Urine flow curve is the plot of velocity of the voided urine against time. The urine stream is affected by voiding pressure (detrusor power) and bladder outlet resistance. Therefore, uroflowmetry evaluates the interaction of the urinary bladder expelling strength and bladder outlet resistance. This is the initial, non-invasive urodynamic investigation for evaluation of patients with lower urinary tract symptoms (LUTS). Although, it is very simple and widely used urodynamic test, the results are nonspecific and required caution interpretations. In the next few pages we will review some aspects of this test, i.e. brief history, equipment, indications, procedure itself and interpretation of the results.  相似文献   
80.
BACKGROUND AND AIMS: We previously reported that the sole clinicopathological parameters of carcinomas diagnosed in a single institution in 1975 differed from those in patients diagnosed in 1995. The findings might be compatible with the loss of importance of the microsatellite instability of the carcinogenic pathway. MATERIALS AND METHODS: We examined the microsatellite status and selected immunomarkers (Ki-67, p53, BAX) in the archival material from 1975 (n=76) and 1995 (n=105). RESULTS AND CONCLUSION: The distribution of tumors showing no microsatellite instability, low microsatellite instability, and high microsatellite instability in the 2-yearly cohorts was similar (1975: 55.6%, 22.2%, 22.2%; 1995: 60.2%, 20.4%, 19.4%, respectively). The percentage of carcinomas showing microsatellite instability at the APC locus differed significantly (1975: 37.5%; 1995: 21.4%). The typical clinicopathological parameters of carcinomas exhibiting high microsatellite instability were largely shared by the carcinomas demonstrating instability at the APC locus. The carcinomas resected in 1995 more frequently demonstrated high expression of an antiapoptotic protein BAX and a different distribution of their Ki-67 proliferation fraction. The evolution of colorectal carcinoma in Poland also involves qualitative changes, including its genetic background.  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