全文获取类型
收费全文 | 9632篇 |
免费 | 959篇 |
国内免费 | 46篇 |
专业分类
耳鼻咽喉 | 132篇 |
儿科学 | 365篇 |
妇产科学 | 205篇 |
基础医学 | 1318篇 |
口腔科学 | 212篇 |
临床医学 | 1251篇 |
内科学 | 2100篇 |
皮肤病学 | 84篇 |
神经病学 | 1034篇 |
特种医学 | 365篇 |
外国民族医学 | 2篇 |
外科学 | 1195篇 |
综合类 | 247篇 |
一般理论 | 7篇 |
预防医学 | 871篇 |
眼科学 | 107篇 |
药学 | 560篇 |
中国医学 | 6篇 |
肿瘤学 | 576篇 |
出版年
2021年 | 99篇 |
2019年 | 100篇 |
2018年 | 135篇 |
2017年 | 124篇 |
2016年 | 139篇 |
2015年 | 138篇 |
2014年 | 199篇 |
2013年 | 301篇 |
2012年 | 402篇 |
2011年 | 396篇 |
2010年 | 248篇 |
2009年 | 248篇 |
2008年 | 397篇 |
2007年 | 439篇 |
2006年 | 440篇 |
2005年 | 399篇 |
2004年 | 383篇 |
2003年 | 375篇 |
2002年 | 360篇 |
2001年 | 353篇 |
2000年 | 353篇 |
1999年 | 304篇 |
1998年 | 125篇 |
1997年 | 101篇 |
1996年 | 133篇 |
1995年 | 106篇 |
1994年 | 86篇 |
1993年 | 90篇 |
1992年 | 237篇 |
1991年 | 218篇 |
1990年 | 226篇 |
1989年 | 228篇 |
1988年 | 230篇 |
1987年 | 231篇 |
1986年 | 167篇 |
1985年 | 187篇 |
1984年 | 132篇 |
1983年 | 108篇 |
1982年 | 70篇 |
1981年 | 100篇 |
1980年 | 77篇 |
1979年 | 120篇 |
1978年 | 90篇 |
1977年 | 100篇 |
1976年 | 88篇 |
1975年 | 88篇 |
1974年 | 87篇 |
1973年 | 74篇 |
1972年 | 70篇 |
1969年 | 70篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Supannee Sripanyakorn Ravin Jugdaohsingh Adrian Mander Sarah L Davidson Richard PH Thompson Jonathan J Powell 《Journal of bone and mineral research》2009,24(8):1380-1388
The “J shape” curve linking the risk of poor bone health to alcohol intake is now well recognized from epidemiological studies. Ethanol and nonethanol components of alcoholic beverages could influence bone remodeling. However, in the absence of a solid underlying mechanism, the positive association between moderate alcoholic intake and BMD remains questionable because of confounding associated social factors. The objective of this work was to characterize the short‐term effects of moderate alcohol consumption on circulating bone markers, especially those involved in bone resorption. Two sequential blood‐sampling studies were undertaken in fasted healthy volunteers (age, 20–47 yr) over a 6‐h period using beer of different alcohol levels (<0.05–4.6%), solutions of ethanol or orthosilicic acid (two major components of beer), and water ± calcium chloride (positive and negative controls, respectively). Study 1 (24 subjects) assessed the effects of the different solutions, whereas study 2 (26 subjects) focused on ethanol/beer dose. Using all data in a “mixed effect model,” we identified the contributions of the individual components of beer, namely ethanol, energy, low‐dose calcium, and high‐dose orthosilicic acid, on acute bone resorption. Markers of bone formation were unchanged throughout the study for all solutions investigated. In contrast, the bone resorption marker, serum carboxy terminal telopeptide of type I collagen (CTX), was significantly reduced after ingestion of a 0.6 liters of ethanol solution (>2% ethanol; p ≤ 0.01, RM‐ANOVA), 0.6 liters of beer (<0.05–4.6% ethanol; p < 0.02), or a solution of calcium (180 mg calcium; p < 0.001), but only after calcium ingestion was the reduction in CTX preceded by a significant fall in serum PTH (p < 0.001). Orthosilicic acid had no acute effect. Similar reductions in CTX, from baseline, were measured in urine after ingestion of the test solutions; however, the biological variability in urine CTX was greater compared with serum CTX. Modeling indicated that the major, acute suppressive effects of moderate beer ingestion (0.6 liters) on CTX were caused by energy intake in the early phase (~0–3 h) and a “nonenergy” ethanol component in the later phase (~3 to >6 h). The early effect on bone resorption is well described after the intake of energy, mediated by glucagon‐like peptide‐2, but the late effect of moderate alcohol ingestion is novel, seems to be ethanol specific, and is mediated in a non–calcitonin‐ and a non–PTH‐dependent fashion, thus providing a mechanism for the positive association between moderate alcohol ingestion and BMD. 相似文献
992.
The effects of selective ibotenate lesions of the complete hippocampus (CHip), the hippocampal ventral pole (VP), or the medial prefrontal cortex (mPFC) in male rats were assessed on several measures related to energy regulation (i.e., body weight gain, food intake, body adiposity, metabolic activity, general behavioral activity, conditioned appetitive responding). The testing conditions were designed to minimize the nonspecific debilitating effects of these surgeries on intake and body weight. Rats with CHip and VP lesions exhibited significantly greater weight gain and food intake compared with controls. Furthermore, CHip-lesioned rats, but not rats with VP lesions, showed elevated metabolic activity, general activity in the dark phase of the light-dark cycle, and greater conditioned appetitive behavior, compared with control rats without these brain lesions. In contrast, rats with mPFC lesions were not different from controls on any of these measures. These results indicate that hippocampal damage interferes with energy and body weight regulation, perhaps by disrupting higher-order learning and memory processes that contribute to the control of appetitive and consummatory behavior. 相似文献
993.
994.
995.
A systematic review and economic evaluation of adefovir dipivoxil and pegylated interferon-alpha-2a for the treatment of chronic hepatitis B 总被引:2,自引:0,他引:2
Standard treatments for chronic hepatitis B (CHB) include interferon-alpha (IFN-alpha) and lamivudine (LAM), but these are associated with adverse effects and viral resistance, respectively. The aim of this systematic review and economic evaluation was to assess the clinical effectiveness and cost-effectiveness of two alternative drugs for the treatment of adults with CHB: adefovir dipivoxil (ADV) and pegylated IFN-alpha-2a. We searched electronic databases, including Cochrane Systematic Reviews and Medline, for literature that met criteria defined in a research protocol. Retrieved articles were independently assessed for inclusion by two reviewers. We developed a Markov state transition model to estimate the cost-effectiveness (cost-utility) of pegylated IFN-alpha-2a and of ADV compared with nonpegylated IFN-alpha-2a, LAM and best supportive care. Seven randomized controlled trials and two systematic reviews met the inclusion criteria for our review of clinical effectiveness. ADV was significantly more effective than placebo or ongoing LAM in reducing levels of hepatitis B virus (HBV) DNA. Rates of hepatitis B e antigen (HBeAg) seroconversion were higher among patients receiving ADV than either placebo or ongoing LAM. Patients treated with pegylated IFN-alpha-2a, either as monotherapy or in combination with LAM, showed significantly reduced HBV DNA levels compared with patients treated with LAM monotherapy. HBeAg seroconversion rates at follow-up were significantly higher for pegylated IFN-alpha-2a patients than for those receiving LAM monotherapy. Results of our cost-effectiveness analysis demonstrate that incremental costs per quality adjusted life year (QALY) for a range of comparisons were between 5,994 and 16,569 British Pound, and within the range considered by NHS decision-makers to represent good value for money. 相似文献
996.
Ritmeijer K Davies C van Zorge R Wang SJ Schorscher J Dongu'du SI Davidson RN 《Tropical medicine & international health : TM & IH》2007,12(3):404-414
During an epidemic of visceral leishmaniasis (VL) in eastern Sudan, Médecins Sans Frontières distributed 357,000 insecticide-treated bednets (ITN) to 155 affected villages between May 1999 and March 2001. To estimate the protective effect of the ITN, we evaluated coverage and use of ITN, and analysed VL incidence by village from March 1996 to June 2002. We provided ITN to 94% of the individuals >5 years old. Two years later, 44% (95% CI 39-48%) of nets were reasonably intact. Because ITN were mainly used as protection against nuisance mosquitoes, bednet use during the VL transmission season ranged from <10% during the hot dry months to 55% during the beginning of the rainy season. ITN were put up from 9 to 11 p.m., leaving children unprotected during a significant period of sandfly-biting hours after sunset. Regression analysis of incidence data from 114 villages demonstrated a significant reduction of VL by village and month following ITN provision. The greatest effect was 17-20 months post-intervention, with VL cases reduced by 59% (95% CI: 25-78%). An estimated 1060 VL cases were prevented between June 1999 and January 2001, a mean protective effect of 27%. Although results need to be interpreted with caution, this analysis indicates a potentially strong reduction in VL incidence following a community distribution of ITN. The effectiveness of ITN depends on behavioural factors, which differ between communities. 相似文献
997.
Kumar Y Tapuria N Kirmani N Davidson BR 《European journal of gastroenterology & hepatology》2007,19(3):265-276
BACKGROUND: Gastrointestinal cancer tumour markers are valuable in the detection of recurrence following resection or in monitoring response to chemotherapy. CEA, CA19-9, CA-50 and CA72-4 are currently available but are nonspecific and have a low sensitivity. 'Tumour M2-pyruvate kinase' was described by Eigenbrodt around 1985. In cancers the active tetrameric form of the M2 isoenzyme of pyruvate kinase converted to an inactive dimeric form by direct interaction with oncoproteins to channel glucose carbons into DNA synthesis. This review summarizes the current knowledge of this unique tumour marker with regard to its biochemistry, assay and potential use as a diagnostic and screening tool in gastrointestinal cancer. METHODS: A literature search was conducted for entries from 1980 to 2005 using PubMed and NeLH databases using tumour M2-pyruvate kinase, faecal tumour M2-pyruvate kinase, tumour metabolism, tumour markers and carcinoembryonic antigen as keywords. A total of 56 references relevant to tumour M2-pyruvate kinase were retrieved. Eighteen references were clinical studies involving plasma/faecal tumour M2-pyruvate kinase and gastrointestinal cancer. The remaining 38 references were clinical/nonclinical trials and reviews on tumour metabolism and plasma/faecal tumour M2-pyruvate kinase assay. Seven of the 18 clinical studies involved faecal M2-pyruvate kinase. Three of the 11 plasma tumour M2-pyruvate kinase studies were non-English language and were excluded. The sensitivity, specificity, positive predictive and negative predictive value for plasma/serum tumour M2-pyruvate kinase in the detection of gastrointestinal cancer was determined for each of the remaining eight studies. Data for gastrointestinal cancer M2-pyruvate kinase were compared with other gastrointestinal cancer markers. Data from three of the eight studies using a diagnostic cut-off value of 15 U/ml for ethylenediaminetetraacetic acid (EDTA) plasma tumour M2-pyruvate kinase were analysed together as a small meta-analysis. RESULTS: At a diagnostic cut-off value of 15 U/ml for tumour M2-pyruvate kinase in EDTA plasma the sensitivity, specificity, positive predictive and negative predictive value was 57.3, 89, 85.7 and 64.8%, respectively, for colorectal cancers, 62.1, 89, 88 and 64%, respectively, for gastric/oesophageal cancers and 72.5, 89, 58 and 94%, respectively, for pancreatic cancers. As a faecal marker for colorectal cancers, faecal tumour M2-pyruvate kinase has a sensitivity of 73-92% at a cut-off value of 4 U/ml as against 50% sensitivity for Guaiac faecal test. CONCLUSION: Circulating tumour M2-pyruvate kinase is more commonly elevated in oesophageal, gastric and colorectal cancer patients than conventional tumour markers. Faecal M2-pyruvate kinase is a sensitive marker of colorectal cancer. The clinical role of tumour M2-pyruvate kinase in gastrointestinal cancer management should be investigated in large-scale clinical trials. 相似文献
998.
Mirizzi syndrome complicating an anomalous biliary tract: a novel cause of a hugely elevated CA19-9 总被引:3,自引:0,他引:3
A 71-year-old man presented with painful obstructive jaundice, weight loss and an elevated CA19-9 (>16,000 U/ml) (normal levels <39 U/ml). Imaging showed a hilar mass. After biliary stenting, the CA19-9 returned to normal. At surgery, biliary obstruction owing to a gallstone (Type II Mirizzi) was found to be complicating a congenital biliary tract anomaly. The obstructing stone was removed and the anomalous biliary tract reconstructed with a Roux-en-y loop, and the patient made an uneventful recovery and remained normal over a 2-year follow-up. A Type II Mirizzi with a biliary tract anomaly is an undocumented cause of an elevated CA19-9. The possibility of benign disease must be considered even with very high levels of the cancer marker CA19-9 or the opportunity for curative surgery may be missed. 相似文献
999.
Davidson JR 《The Journal of clinical psychiatry》2007,68(Z3):10-15
The term atypical depression as a preferentially monoamine oxidase inhibitor (MAOI)-responsive state was first introduced by West and Dally in 1959. Further characterization of this syndrome and its responsiveness to antidepressants came to occupy the attention of many psychopharmacologists for the next 30 years. Different portrayals of atypical depression have emerged, for example, nonendogenous depression, phobic anxiety with secondary depression, vegetative reversal, rejection-sensitivity, and depression with severe chronic pain. Consistency across or within types has been unimpressive, and no coherent single type of depression can yet be said to be "atypical." In successfully demonstrating superiority of MAOI drugs to tricyclics, the Columbia (or DSM-IV) criteria have established their utility and become widely adopted, but other criteria have also passed this test. In this "post-MAOI" era, no novel compound or group of drugs has been clearly shown to have good efficacy in atypical depression, leaving the treatment of atypical depression as an unmet need. 相似文献
1000.
van Reekum CM Urry HL Johnstone T Thurow ME Frye CJ Jackson CA Schaefer HS Alexander AL Davidson RJ 《Journal of cognitive neuroscience》2007,19(2):237-248
Using functional magnetic resonance imaging, we examined whether individual differences in amygdala activation in response to negative relative to neutral information are related to differences in the speed with which such information is evaluated, the extent to which such differences are associated with medial prefrontal cortex function, and their relationship with measures of trait anxiety and psychological well-being (PWB). Results indicated that faster judgments of negative relative to neutral information were associated with increased left and right amygdala activation. In the prefrontal cortex, faster judgment time was associated with relative decreased activation in a cluster in the ventral anterior cingulate cortex (ACC, BA 24). Furthermore, people who were slower to evaluate negative versus neutral information reported higher PWB. Importantly, higher PWB was strongly associated with increased activation in the ventral ACC for negative relative to neutral information. Individual differences in trait anxiety did not predict variation in judgment time or in amygdala or ventral ACC activity. These findings suggest that people high in PWB effectively recruit the ventral ACC when confronted with potentially aversive stimuli, manifest reduced activity in subcortical regions such as the amygdala, and appraise such information as less salient as reflected in slower evaluative speed. 相似文献