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   1979篇
  免费   126篇
  国内免费   27篇
耳鼻咽喉   8篇
儿科学   175篇
妇产科学   18篇
基础医学   213篇
口腔科学   67篇
临床医学   187篇
内科学   428篇
皮肤病学   42篇
神经病学   100篇
特种医学   345篇
外科学   117篇
综合类   23篇
预防医学   110篇
眼科学   26篇
药学   116篇
  1篇
中国医学   1篇
肿瘤学   155篇
  2024年   2篇
  2023年   10篇
  2022年   18篇
  2021年   35篇
  2020年   24篇
  2019年   27篇
  2018年   47篇
  2017年   38篇
  2016年   44篇
  2015年   45篇
  2014年   52篇
  2013年   93篇
  2012年   69篇
  2011年   67篇
  2010年   72篇
  2009年   106篇
  2008年   46篇
  2007年   79篇
  2006年   64篇
  2005年   48篇
  2004年   33篇
  2003年   33篇
  2002年   26篇
  2001年   21篇
  2000年   21篇
  1999年   31篇
  1998年   101篇
  1997年   117篇
  1996年   112篇
  1995年   78篇
  1994年   82篇
  1993年   99篇
  1992年   17篇
  1991年   17篇
  1990年   18篇
  1989年   44篇
  1988年   39篇
  1987年   26篇
  1986年   32篇
  1985年   31篇
  1984年   17篇
  1983年   15篇
  1982年   19篇
  1981年   34篇
  1980年   20篇
  1979年   8篇
  1978年   8篇
  1977年   21篇
  1976年   19篇
  1975年   6篇
排序方式: 共有2132条查询结果,搜索用时 15 毫秒
991.
Purpose : We consider the hypothesis that proliferative diabetes produces selective loss of colour channels. We also consider the possibility that laser treatment for this condition does not affect macula function. Methods : We tested for the possibility of a selective colour channel involvement in 35 eyes of 33 cases of proliferative diabetes by considering the outcomes of saturation and hue testing before and after pan-retinal photocoagulation (PRP). Saturation testing was achieved with the Sahlgren Saturation Test (SST) and hue testing was via the Farnsworth-Munsell 100 (FM100) hue test. Our results were compared to a recent model1 that was developed to predict the saturation processing of diseased eyes. Results : All diabetic eyes with normal hue (FM100) scores passed the saturation test (SST). Most pre-treatment eyes (29 of 35 or 83 per cent) failed the FM100 hue test but only 16 of 35 (46 per cent) failed the saturation test. Following laser treatment, 97 per cent of eyes were abnormal on the FM100 hue test but only seven per cent failed the saturation test.  相似文献   
992.
993.
BACKGROUND & AIMS: Corticosteroids have been shown to significantly decrease short-term mortality in patients with severe alcoholic hepatitis. However, independent factors associated with a favorable outcome and long-term survival are unknown. The aim of this study was to examine prognostic factors and long-term survival in patients with biopsy-proven severe alcoholic hepatitis. METHODS: Of 183 patients studied, 61 had been randomized in a previous trial; 32 of them were treated with prednisolone (group I) and 29 were not treated (group II); 61 were treated from the end of this randomized trial (group III); and 61 were simulated (group IV). RESULTS: At 1 year, survival in group I (69%; confidence interval [CI], 57%-81%) and group III (71%; CI, 55%- 87%) was better than in the nontreated groups (group II, 41%; CI, 23%- 59%; P = 0.01) (group IV, 50%; CI, 37%-63%; P = 0.05). At 2 years, survival was not significantly different. Treated patients with marked liver polymorphonuclear infiltrate had better 1-year survival (76%; CI, 64%-88%) than the others (53%; CI, 35%-71%; P = 0.05). Treated patients with polymorphonuclear counts of > 5500/mm3 had better 1-year survival (77%; CI, 65%-89%) than the others (40%; CI, 14%-66%; P = 0.003). In the 93 treated patients, liver polymorphonuclear infiltrate (P < 0.03) and polymorphonuclear count (P < 0.001) were independently correlated with 1-year survival. CONCLUSIONS: Prednisolone reduced mortality by at least 1 year. Liver polymorphonuclear infiltrate and polymorphonuclear count were independent prognostic factors. (Gastroenterology 1996 Jun;110(6):1847-53)  相似文献   
994.
Interleukin-1 alpha (IL-1 alpha) and interleukin-1 beta (IL-1 beta) are two biochemically distinct, but distantly related, polypeptidic cytokines that play a key role in inflammation, immunologic reactions, and tissue repair. Recently, it has been shown that IL-1 alpha is identical to hematopoietin 1, which was described as a hematopoietic growth factor acting on early progenitor cells in synergy with other hematopoietic growth factors. In this report we discuss our use of in situ hybridization on human prometaphase cells with a human IL-1 alpha cDNA probe to localize the human IL-1 alpha gene on the proximal part of the long arm of chromosome 2 at band q13, in the same chromosomal region as the IL-1 beta gene.  相似文献   
995.
996.
The uptake of free fatty acids has previously been shown to affect the capping of lymphocytes, and there is evidence that different types of fatty acids may partition into separate lipid domains in cell surface membranes. In studies of gel-filtered human platelets, we found that cis-unsaturated fatty acids (1-35 microM) inhibited platelet shape change, aggregation, and secretion of 5-hydroxytryptamine induced by thrombin, adenosine diphosphate (ADP), collagen, U46619 (a thromboxane A2 analog), or plant lectins, but not that induced by A23187, a calcium ionophore. Trans-unsaturated and saturated fatty acids had little or no inhibitory effect. The inhibitory effects of cis-unsaturated fatty acids were not affected by inhibition of adenylate cyclase or cyclooxygenase. 14C-labeled fatty acids were taken up into platelet lipids. The maximum platelet-inhibitory effect of cis-unsaturated fatty acids was seen when over 90% of the platelet label was still in the form of free fatty acids. Platelet inhibition could be reversed by washing the platelets by gel filtration. Binding of platelet agonists to the platelet was not inhibited by the fatty acids. Cis-unsaturated fatty acids, but not trans-unsaturated or saturated fatty acids, decreased fluorescence polarization of platelets or isolated platelet membranes monitored with 1,6-diphenyl- 1,3,5-hexatriene. The potency of the fatty acids as inhibitors of platelet aggregation was inversely correlated with their melting points. These data suggest that inhibition of receptor-mediated platelet responses by cis-unsaturated fatty acids results from perturbation of the platelet membrane in specific lipid domains.  相似文献   
997.
Introduction: The epidemic of diabetes has now taken on epic proportions and therefore reducing the impact of diabetic complications represents one of the major global challenges in improving health and well-being worldwide. Preventing the development of diabetic kidney disease (DKD) is particularly important, as diabetes is one of the main risk factors for the development of chronic kidney disease, which in turn is strongly linked to development of cardiovascular disease, end-stage renal failure, hospitalization and premature death. Intensive glucose-lowering treatment has been shown to prevent and slow progression of DKD, yet to date, only certain populations have benefited from this intervention.

Areas covered: We review the evidence for existing glucose-lowering treatments in the prevention of DKD, and research into techniques to better target individuals who will benefit from these therapies.

Expert opinion: Diabetic patients with established kidney disease may benefit from glucose-lowering treatment, particularly if a safer side-effect profile of these treatments is achieved. Better understanding of glucose homeostasis and evaluation of compounds inhibiting its downstream effects are required in order to improve the outlook for individuals with DKD. An additional approach to improve the success rate of glucose-lowering treatment is to improve the selection of individuals who may benefit from treatment. A potential means to identify such subjects could involve the use of biomarkers.  相似文献   

998.
BACKGROUND: Methotrexate (MTX) use is associated with hepatic fibrosis in psoriasis patients. To monitor this serial liver biopsies were performed. The Fibroscan and the Fibrotest are two novel, non-invasive methods that might be able to assess MTX-induced hepatic fibrosis. AIM: Evaluating the accuracy and feasibility of the Fibroscan and Fibrotest to detect significant MTX-induced liver fibrosis in psoriasis patients. Methods: We assessed 24 psoriasis patients who had a recent liver biopsy during MTX use. The results from the Fibroscan and Fibrotest were compared with liver histology. RESULTS: Fibroscan values (n=20) ranged between 3.3 and 18.4 kPa (median value 6.4 kPa) and correctly identified 88% of the patients without significant liver fibrosis (Metavir score /=F2, Fibrotest >0.31). CONCLUSION: In this population, Fibrotest accurately predicted the presence of significant liver fibrosis while the Fibroscan accurately predicted the absence of significant liver fibrosis in MTX users. This suggests that a combination of Fibrotest and Fibroscan should prospectively be evaluated in monitoring and detecting significant MTX-induced liver fibrosis in psoriasis patients.  相似文献   
999.
Plantar intrinsic foot muscles provide structure to the foot during walking and thus regulate mechanical foot sole stresses. When paralyzed, for instance in leprosy patients with neuropathy of the distal part of the tibial nerve, there is a high prevalence of plantar ulceration and deformities, especially when muscle weakness goes together with loss of foot sole sensibility. These patients should get immediate care involving education, special footwear and reconstructive surgery before further foot impairment and deformity becomes manifest. Thus far, in leprosy patients little attention is paid to screening of plantar intrinsic muscles activity. This can be done with a new simple and non-invasive method, the Paper Grip Test (PGT). There are two variants for detecting intrinsic muscle weakness of the foot, PGT1 for the great toe and PGT2 for the combined lesser toes. In this study, 517 leprosy patients and 170 healthy volunteers were investigated with the PGT. Sensibility of the foot sole was tested by means of a 10 gram monofilament. Specificity to the PGT1 is found to be about 95.3% which is considered good for physical diagnostic tests. PGT2 is less specific than PGT1. Individual muscle power and understanding of the patient seems to influence the outcome of the test to a certain extent. Sensitivity can only be calculated when the diagnosis is confirmed by electromyography. Especially patients with anesthetic feet, females, older patients and patients with PN-, BB- or LL-types of leprosy appeared to have a higher prevalence of intrinsic foot muscle weakness. All results were analyzed by means of the bivariate Pearson correlation-analysis and proved to be statistically significant (p = < 0.05). It is concluded that the PGT1, more than the PGT2, is a useful screening test on the function of plantar intrinsic foot muscles in leprosy patients in hospitals and during fieldwork in developing countries.  相似文献   
1000.
Escherichia coli minicells containing the plasmid pSC101 (approximately 10 kb) or pBR322 (approximately 4 kb) were opsonized and incubated with human neutrophils. The neutrophils responded to the minicells as they would to native E coli: they ingested the minicells, discharged their granule contents into the minicell-containing phagosomes, and expressed a respiratory burst. After one hour of incubation, the fate of the ingested plasmid DNA was examined. No DNA degradation was detected by trichloroacetic acid precipitation or agarose gel electrophoresis. Moreover, when pBR322 recovered from ingested minicells was transformed into E coli, no mutations in either of the antibiotic resistance genes carried by the plasmid were detected out of many thousand transformants screened. These findings confirm the surprisingly limited effect of neutrophils on ingested DNA.  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