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   3087篇
  免费   248篇
  国内免费   8篇
耳鼻咽喉   21篇
儿科学   75篇
妇产科学   29篇
基础医学   425篇
口腔科学   234篇
临床医学   332篇
内科学   683篇
皮肤病学   34篇
神经病学   246篇
特种医学   117篇
外科学   349篇
综合类   13篇
一般理论   1篇
预防医学   193篇
眼科学   93篇
药学   286篇
肿瘤学   212篇
  2023年   36篇
  2022年   43篇
  2021年   93篇
  2020年   73篇
  2019年   86篇
  2018年   98篇
  2017年   83篇
  2016年   111篇
  2015年   104篇
  2014年   150篇
  2013年   192篇
  2012年   240篇
  2011年   250篇
  2010年   122篇
  2009年   105篇
  2008年   179篇
  2007年   152篇
  2006年   167篇
  2005年   145篇
  2004年   134篇
  2003年   130篇
  2002年   113篇
  2001年   40篇
  2000年   34篇
  1999年   49篇
  1998年   44篇
  1997年   33篇
  1996年   25篇
  1995年   18篇
  1994年   11篇
  1993年   11篇
  1992年   15篇
  1991年   21篇
  1990年   20篇
  1989年   23篇
  1988年   13篇
  1987年   20篇
  1986年   19篇
  1985年   26篇
  1984年   15篇
  1983年   20篇
  1982年   12篇
  1981年   4篇
  1980年   8篇
  1979年   10篇
  1978年   4篇
  1977年   11篇
  1975年   5篇
  1974年   4篇
  1971年   3篇
排序方式: 共有3343条查询结果,搜索用时 31 毫秒
1.
TL1A is a TNF‐like cytokine which has been shown to co‐stimulate TH1 and TH17 responses during chronic inflammation. The expression of this novel cytokine has been investigated in inflammatory disorders like rheumatoid arthritis and inflammatory bowel disease, but little is known about expression and induction in psoriasis. Indeed, the pathogenesis in psoriasis is still not fully understood and it is speculated that cytokines other than TNF‐α are important in subsets of patients. Also, for patients with severe disease that are treated with systemic anti‐TNF‐α blockade, novel candidates to be used as disease and response biomarkers are of high interest. Here, we demonstrate TL1A expression in biopsies from psoriatic lesions. Also, we investigated spontaneous and induced TL1A secretion from PBMCs and blood levels from a cohort of psoriasis patients. Here, increased spontaneous secretion from PBMCs was observed as compared to healthy controls and a small subset of patients had highly elevated TL1A in the blood. Interestingly, activation of PBMCs with various cytokines showed a decreased sensitivity for TL1A activation in psoriasis patients compared to healthy controls.TL1A levels in blood and biopsies could not be correlated with disease activity with this patient cohort. Thus, additional large‐scale studies are warranted to investigate TL1A as a biomarker.  相似文献   
2.
3.
4.
32nd Annual Meeting of the Scandinavian Society for Psychopharmacology Copenhagen, Denmark April 10–12, 1991 Abstracts  相似文献   
5.
Semantic verbal fluency tasks are commonly used in neuropsychological assessment. Investigations of the influence of level of literacy have not yielded consistent results in the literature. This prompted us to investigate the ecological relevance of task specifics, in particular, the choice of semantic criteria used. Two groups of literate and illiterate subjects were compared on two verbal fluency tasks using different semantic criteria. The performance on a food criterion (supermarket fluency task), considered more ecologically relevant for the two literacy groups, and an animal criterion (animal fluency task) were compared. The data were analysed using both quantitative and qualitative measures. The quantitative analysis indicated that the two literacy groups performed equally well on the supermarket fluency task. In contrast, results differed significantly during the animal fluency task. The qualitative analyses indicated differences between groups related to the strategies used, especially with respect to the animal fluency task. The overall results suggest that there is not a substantial difference between literate and illiterate subjects related to the fundamental workings of semantic memory. However, there is indication that the content of semantic memory reflects differences in shared cultural background--in other words, formal education--, as indicated by the significant interaction between level of literacy and semantic criterion.  相似文献   
6.
7.
1. The nitric oxide (NO)-releasing properties of two new mesoionic 3-aryl substituted oxatriazole-5-imine derivatives (GEA 3162 and GEA 3175) were characterized and compared with the known NO-donors 3-morpholino-sydnonimine (SIN-1) and S-nitroso-N-acetylpenicillamine (SNAP). 2. GEA 3162, GEA 3175, SIN-1 and SNAP inhibited adenosine 5'-diphosphate-induced platelet aggregation (IC50 values 0.18, 0.39, 3.73 and 2.12 microM, respectively). All four compounds induced a dose-dependent and more than 4 fold increase in cyclic GMP in platelets. The increase in cyclic GMP concentration was potentiated more than 1.5 fold by a phosphodiesterase inhibitor, zaprinast (10 microM) and inhibited 38-97% by oxyhaemoglobin (10-45 microM). 3. All of the four compounds studied converted oxyhaemoglobin to methaemoglobin and formed a paramagnetic NO-haemoglobin complex. All but GEA 3175 formed nitrite and nitrate in phosphate buffer. During a 40 min incubation, GEA 3162, SIN-1 and SNAP (100 microM) produced 50-70 microM NO2- + NO3- as determined by high performance liquid chromatography. The release of NO and NO2 by GEA 3175 was increased 140 fold in the presence of human plasma (0.14 and 19.7 ppb in the absence and presence of 1% human plasma, respectively) as analyzed by ozone chemiluminescence. 4. The results suggest that the mesoionic 3-aryl substituted oxatriazole-5-imine derivatives GEA 3162 and GEA 3175 as well as SIN-1 and SNAP release nitric oxide.  相似文献   
8.
BACKGROUND. Cigarette smoking is a risk factor for cardiovascular disease. The present study addressed the effect of tobacco use on the formation of two eicosanoids, thromboxane A2 and prostacyclin, which have been implicated in both acute and chronic cardiovascular disorders. METHODS AND RESULTS. In 577 randomly sampled 18-19-year-old men, the urinary excretion of the 2,3-dinor metabolites of thromboxane A2 and prostacyclin (Tx-M and PGI-M, respectively) was analyzed and related to the subjects' self-reported use of tobacco. Sixty-five percent of the subjects used no tobacco, 7.5% were cigarette smokers, 22% used wet (oral) snuff, and the rest reported a mixed use of tobacco. The urinary excretion of Tx-M was higher (p less than 0.001) in cigarette smokers than in those not using tobacco (180 versus 128 pg/mg creatinine) and was correlated (r = 0.35, p less than 0.05) with the daily cigarette consumption. Snuff users had no increase in their urinary excretion of Tx-M, despite urinary cotinine levels comparable to those in the cigarette smokers (1,210 and 1,560 ng/ml, respectively). The excretion of PGI-M did not differ between non-tobacco users, cigarette smokers, and snuff users. CONCLUSIONS. We conclude that cigarette smoking, but not the use of snuff, facilitates the formation of thromboxane A2. We propose that such an increased formation reflects platelet activation in the absence of vascular injury and that it may be of significance for the subsequent development of cardiovascular disease.  相似文献   
9.
This study presents an analysis on longitudinal tumour marker series in twenty-two patients with non-seminomatous germ cell cancers treated with cisplatinum (DDP) based combination chemotherapy. Series of alphafoetoprotein (AFP), human chorionic gonadotropin (HCG) and lactate dehydrogenase (LDH) were analyzed applying a dynamic mathematical marker model. The model analysis provided quantitated values for growth rate and treatment response in the marker producing cells. The analysis showed that LDH had to be above 2 000 U/l to be a trustworthy tumour marker. HCG producing cells tended to grow faster than AFP producing cells, and were 3-5-fold more sensitive to the chemotherapy given than AFP producing cells. Treatment response versus DDP dose appeared to be bi-phasic, but with no significant change in treatment efficiency within the given range of DDP doses.  相似文献   
10.
The diagnostic efficacy of clinical history (CH), skin prick test (SPT) and RAST was estimated in relation to nasal and conjunctival provocation tests (NPT, CPT) in 69 patients with seasonal rhinoconjunctivitis. The extracts used were freeze-dried, and biologically standardized birch and timothy allergen preparations matched to the extracts on Phadebas RAST discs. Based on single determinations the sensitivity, specificity and predictive values were calculated. There were highly significant (P less than 0.001) correlations between all parameters: NPT, CPT, CH, SPT and RAST. For birch the combination of SPT and RAST made the PTs superfluous as both sensitivity and specificity then reached 100%. With timothy the sensitivity was 97% and with the addition of CH 100%. However, the specificity was only 79% through combining CH, SPT and RAST. The present study using the same standardized allergen preparation in all tests showed a good correlation between indirect test results and provocation tests.  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