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   1316篇
  免费   65篇
  国内免费   4篇
耳鼻咽喉   39篇
儿科学   81篇
妇产科学   73篇
基础医学   117篇
口腔科学   28篇
临床医学   118篇
内科学   245篇
皮肤病学   32篇
神经病学   76篇
特种医学   76篇
外科学   223篇
综合类   17篇
预防医学   45篇
眼科学   86篇
药学   61篇
中国医学   1篇
肿瘤学   67篇
  2024年   1篇
  2023年   8篇
  2022年   22篇
  2021年   38篇
  2020年   37篇
  2019年   32篇
  2018年   37篇
  2017年   33篇
  2016年   44篇
  2015年   36篇
  2014年   46篇
  2013年   88篇
  2012年   102篇
  2011年   129篇
  2010年   47篇
  2009年   40篇
  2008年   90篇
  2007年   77篇
  2006年   94篇
  2005年   76篇
  2004年   64篇
  2003年   64篇
  2002年   70篇
  2001年   25篇
  2000年   15篇
  1999年   15篇
  1998年   9篇
  1997年   6篇
  1996年   5篇
  1995年   5篇
  1994年   2篇
  1993年   1篇
  1992年   5篇
  1991年   1篇
  1990年   1篇
  1988年   2篇
  1987年   1篇
  1986年   2篇
  1984年   1篇
  1982年   1篇
  1977年   1篇
  1975年   1篇
  1974年   2篇
  1972年   2篇
  1971年   1篇
  1970年   2篇
  1968年   3篇
  1966年   1篇
排序方式: 共有1385条查询结果,搜索用时 15 毫秒
61.
Effect of methylprednisolone (MP), tirilazad mesylate (TM) and vitamin E on lipid peroxidation (LP) was evaluated in an experimental model of spinal cord compression injury in anesthetized rats. Forty rats, divided randomly into four groups, were injured by compressing on the spinal cord at Th 3 for 1 min. Bolus injections of saline solution, MP (30 mg/kg bolus and 5.4 mg/kg/h), TM (10 mg/kg four times per day), or vitamin E (30 mg/ kg four times per day) were begun 1 h after the spinal cord injury (SCI). Twenty-four hours after treatment, the rats were killed, and malondialdehyde (MDA), a LP product, was measured in the spinal cord tissues. Rats treated with MP, TM and vitamin E had significantly decreased MDA levels (P<0.01) than rats in the control group. The lowest MDA levels were found in the TM group. These results suggest that MP, TM and vitamin E may have a protective effect against SCI in rats by its antioxidant effect.  相似文献   
62.
63.
64.
Cronobacter spp. (formerly Enterobacter sakazakii) can be isolated from a wide range of foods and environments, and its association with neonatal infections has drawn considerable attention from regulatory authorities. The principle route of neonatal infection has been identified as the ingestion of contaminated infant formula. A number of methods have been developed to identify Cronobacter spp., however these were before the most recent (2012) taxonomic revision of the genus into seven species. In this study, phenotyping, protein profiling and molecular methods were used to identify Cronobacter strains which had been recently isolated from ingredients used in the preparation of infant formula.Pulsed field gel electrophoresis revealed that different Cronobacter strains had been recovered from the same food products. All isolates were identified as Cronobacter sakazakii according to four genus specific PCR-probes and protein profiling using MALDI-TOF analysis. However, 16S rDNA sequence analyses and fusA allele sequencing gave more accurate identification: four strains were C. sakazakii, one strain was Cronobacter malonaticus and the remaining strain was Cronobacter universalis. Multilocus sequence typing showed the strains were different sequence types.These results demonstrate the presence of different Cronobacter species in food ingredients used in the preparation of infant formula, and also the need for molecular identification and profiling methods to be revised according to taxonomic revisions.  相似文献   
65.
AimsOur aim was to evaluate the effects of endothelial nitric oxide synthase (eNOS) E298D polymorphism in obesity variables and essential hypertension (eHT) development risk. The genotype frequencies of E298D polymorphism in eHT patients and non-hypertensive (non-HT) controls (proven to have normal coronaries angiographically) were analyzed for their association with demographic and obesity related data of the eHT patients and controls.Materials and methodseNOS gene E298D genotypes were determined with qPCR.ResultsThe eNOS E298D polymorphism frequencies for 298E/E, 298E/D and 298D/D genotypes were respectively as 41.1%, 44.6%, 14.3% in subjects eHT and 52.8%, 38.9%, 8.3% in the non-HT groups. The combined E298D homozygous polymorphic and heterozygous genotypes were found to have a decreasing effect on serum total-cholesterol levels in comparison to wild-type genotypes in eHT patients but not controls.ConclusionsOur results support the idea that, the eNOS E298D polymorphism, which is not associated with hypertension, may increase the risk of hypertension when associated with high serum total-cholesterol levels.  相似文献   
66.
67.
Leiomyomas of the external genitalia are uncommon soft tissue tumors. We report the case of a 47-year-old woman with perineal leiomyomas mimicking Bartholin's gland mass according to the preoperative magnetic resonance imaging (MRI) findings. Leiomyomas in the vulvar region should be differentiated from complicated Bartholin’s gland cysts and preoperative MRI findings may be misleading. The complete surgical excision should be the choice of treatment  相似文献   
68.
In order to investigate the ability of Mycobacterium bovis BCG vaccination to induce immune responses toward different classes of mycobacterial antigens and the cell populations involved in such responses, proliferation of distinct human lymphocyte subsets from BCG-vaccinated donors in response to different subcellular fractions of BCG was analysed and compared with that of not sensitized subjects. Proliferation of different cell subsets was evaluated by flow cytometric determination of bromodeoxyuridine incorporated into DNA of dividing cells and simultaneous identification of cell surface markers. Although a certain degree of variability was observed among different donors, after 6 days of in vitro stimulation BCG-vaccinated subjects displayed, as a mean, a stronger blastogenic response to all the classes of antigens compared with non-sensitized ones. PPD, culture filtrates and membrane antigens induced a predominant proliferation of CD4+ T cells. In contrast, preparations enriched in cytosolic antigens elicited strong proliferation of gammadelta+ T cells which, as a mean, represented 55% of the proliferating cells. Although to a lesser extent, proliferation of gammadelta+ T cells was also elicited by preparations enriched in membrane and cell wall antigens. In response to the latter preparation proliferation of CD4+ T cells and CD16+/CD3- (natural killer (NK)) cells was observed, as well. In particular, cell wall antigens were found to induce significantly higher levels of proliferation of NK cells compared with all the other classes of antigens.  相似文献   
69.
Polyhydroxyethyl methacrylate (pHEMA) membranes coated on one side with chondroitin sulfate (CS) were used to block adhesion physically and to reduce friction between healing flexor tendons and the surrounding tissue in rabbit forepaws after surgical repair. Digits with pHEMA-only, standard tendon sheath repair, and with no sheath repair were the controls. Over 12 weeks the CS-coated membranes were evaluated for joint flexion, adhesion limitation, and tendon healing progress. The membranes initially allowed for better flexion (ie, for 6 weeks), but their relative superior effectiveness faded afterward. Histology showed that adhesions were less severe and healing was better in the CS-pHEMA membranes at 3 and 6 weeks. If further studies determine precise amounts or thicknesses of CS coats that will maximize its healing properties, CS-pHEMA should prove useful in clinical settings in which restoration of tendon sheath integrity with a minimum of adhesions is not possible.  相似文献   
70.
The aim of the present study was to improve the viability of marginal livers from non-heart beating donors upon cold preservation using two different techniques for the provision of tissue aerobiosis. Livers from male Wistar rats (250-300 g bw) were harvested after 60 min of cardiac arrest, flushed via the portal vein with 20 mL of heparinized Ringer's solution and 60 mL of histidine-tryptophan-ketoglutarate (HTK) preservation solution. Control livers were then stored submerged in HTK for 24 h at 4 degrees C while other organs were subjected to aerobic conditions by either insufflation of gaseous oxygen via the venous vascular system of the cold stored organ (VSOP) or pulsatile machine perfusion (MP) with oxygenated HTK at 5 mL/min at 4 degrees C. Superoxide dismutase (SOD) (7500 IU) was added to the last 10 mL of HTK in order to prevent adverse effects of high oxygen tensions at hypothermia. Viability of the livers was assessed upon isolated perfusion in vitro with oxygenated Krebs-Henseleit buffer at constant flow. VSOP or MP, both significantly improved vascular conductivity upon reperfusion as evaluated by portal venous pressure, reduced hepatic enzyme release and led to a rise in hepatic bile production upon reperfusion. Induction of apoptosis was also looked for in tissue homogenates by Western analysis for cleavage of poly(ADP-ribose)polymerase (PARP). Expression of cleaved PARP fragment could be found in reperfused control livers but also, though to a lesser extend, after VSOP or MP. In conclusion, provision of oxygen during cold preservation significantly contributes to improve organ viability upon reperfusion and must be regarded as a useful adjunct for marginal or pre-damaged livers. HTK has been shown for the first time to be also suitable for long-term MP preservation of the liver, but, as inferred from these data, simple insufflation of gaseous O2 may be considered a feasible alternative.  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