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   7843篇
  免费   408篇
  国内免费   38篇
耳鼻咽喉   80篇
儿科学   321篇
妇产科学   82篇
基础医学   784篇
口腔科学   153篇
临床医学   624篇
内科学   2049篇
皮肤病学   106篇
神经病学   529篇
特种医学   448篇
外科学   1248篇
综合类   140篇
一般理论   6篇
预防医学   370篇
眼科学   270篇
药学   530篇
中国医学   25篇
肿瘤学   524篇
  2024年   3篇
  2023年   45篇
  2022年   90篇
  2021年   219篇
  2020年   152篇
  2019年   166篇
  2018年   212篇
  2017年   147篇
  2016年   211篇
  2015年   227篇
  2014年   348篇
  2013年   400篇
  2012年   687篇
  2011年   715篇
  2010年   403篇
  2009年   323篇
  2008年   534篇
  2007年   594篇
  2006年   551篇
  2005年   496篇
  2004年   476篇
  2003年   406篇
  2002年   362篇
  2001年   60篇
  2000年   67篇
  1999年   69篇
  1998年   57篇
  1997年   36篇
  1996年   25篇
  1995年   28篇
  1994年   27篇
  1993年   16篇
  1992年   14篇
  1991年   21篇
  1990年   12篇
  1989年   18篇
  1988年   14篇
  1987年   10篇
  1986年   9篇
  1985年   3篇
  1984年   5篇
  1983年   5篇
  1982年   2篇
  1981年   2篇
  1979年   4篇
  1978年   3篇
  1975年   2篇
  1974年   5篇
  1970年   2篇
  1965年   2篇
排序方式: 共有8289条查询结果,搜索用时 453 毫秒
61.
PURPOSE: This retrospective study was designed to classify choledochal cysts on the basis of the findings of hepatobiliary scintigraphy. METHODS: Twenty-one patients with choledochal cysts (15 female, 6 male; mean age, 20 years) proved on the findings of endoscopic retrograde cholangiopancreatography (ERCP) or surgery and histopathologic analysis were included in the study. Two nuclear medicine physicians, blinded with regard to cholangiographic and operative details, were asked to review and to classify the type of choledochal cyst seen on the hepatobiliary scan. Later, scintigraphic results were compared with ERCP and surgical findings for a reference standard. RESULTS: The findings of hepatobiliary scintigraphy correlated with ERCP and surgical findings in 18 of 21 cases (86%). Scintiscans correctly identified all type 1 cysts (12/12). The sensitivity of scintigraphy in diagnosing type 4 cysts was 66% (6 of 9 cases). It underestimated the intrahepatic extent of disease in type 4a biliary cysts (37%). CONCLUSION: This study illustrates the utility of hepatobiliary scintigraphy in diagnosing type 1 and 4 choledochal cysts.  相似文献   
62.
63.
64.
PURPOSE: We recently showed that metastasis-promoting Mts1 gene (S100A4) and protein is overexpressed during progression of prostate cancer in humans. The purpose of this study was to assess the expression of S100A4 during autochthonous prostate cancer progression in transgenic adenocarcinoma of the mouse prostate (TRAMP) model. Because oral consumption of green tea polyphenols (GTP) has been shown to inhibit metastasis and prostate cancer in TRAMP, we further assessed the significance of S100A4 during chemoprevention regimen. EXPERIMENTAL DESIGN: Male TRAMP mice 8 weeks of age were equally divided into two groups. A freshly prepared 0.1% GTP solution in tap water was supplied thrice a week to experimental animals as the sole source of drinking fluid for 24 weeks, whereas the control group of animals received the same tap water throughout the experiment. The animals were sacrificed at 0, 8, 16, and 24 weeks of GTP feeding and were analyzed for S100A4 and E-cadherin. Additional untreated and treated nontransgenic controls were also included in the study. RESULTS: With the progression of age and prostate cancer growth in TRAMP mice, an increase in the expression of S100A4 at mRNA and protein level in dorsolateral prostate, but not in nontransgenic mice, occurred. GTP feeding to TRAMP mice resulted in marked inhibition of prostate cancer progression, which was associated with reduction of S100A4 and restoration of E-cadherin. CONCLUSIONS: S100A4 represents a promising marker for prostate cancer progression and could be employed as a biomarker in chemoprevention regimens.  相似文献   
65.
Dextroamphetamine administration in healthy controls produces a range of subjective and physiological effects, which have been likened to those occurring during mania. However, it is uncertain if these can be attenuated by lithium since conflicting results have been reported. To date there have been no previous studies examining the effects of valproate on dextroamphetamine-induced mood and physiological changes. The current study was a double-blind, placebo-controlled, study in which volunteers received either 1000 mg sodium valproate (n = 12), 900 mg lithium (n = 9), or placebo (n = 12) pre-treatment for 14 days. Subjective and physiological measures were then obtained prior to administration of a 25 mg dose of dextroamphetamine, and at two time points after administration. Differences in the response to dextroamphetamine were assessed between the three treatment groups. The results of this study show that pre-treatment with lithium only significantly attenuated dextroamphetamine-induced change in happiness, while valproate pre-treatment significantly attenuated the effects of dextroamphetamine on happiness, energy, alertness and on the diastolic blood pressure. These results suggest that lithium and valproate do not have the same mechanism of action on dextroamphetamine-induced changes, and this finding may relate to differences in their mechanism of action in mood disorders.  相似文献   
66.
Extended release formulation of glipizide based on osmotic technology was developed and evaluated. The effect of different formulation variables, namely, level of solubility modifier in the core, membrane weight gain, and level of pore former in the membrane, were studied. Drug release was found to be affected by the level of solubility modifier in the core formulation. Glipizide release was inversely proportional to the membrane weight but directly related to the initial level of pore former (PVP) in the membrane. Burst strength of the exhausted shells increased with the weight gain of the membrane. On the other hand, burst strength decreased with an increase in the level of pore former in the membrane. Drug release from the developed formulations was independent of pH and agitational intensity, but dependent on the osmotic pressure of the release media. Results of SEM studies showed the formation of pores in the membrane from where the drug release occurred. The numbers of pores were directly proportional to the initial level of pore former in the membrane. The manufacturing procedure was found to be reproducible and formulations were stable after 3 months of accelerated stability studies.  相似文献   
67.
68.
69.
Background and aimsPatients with diabetes mellitus (DM) often demonstrate impaired antibody response to influenza/hepatitis B vaccines. Hence, we compared anti-SARS-CoV-2 antibody response in non-severe COVID-19 patients with and without type 2 diabetes mellitus (T2DM).MethodsRecords of non-severe COVID-19 patients admitted at our institution between April 10, 2020 and May 20, 2020 were retrieved. Qualitative detection of total (IgG + IgM) anti-SARS-CoV-2 antibody was performed using electrochemiluminescence immunoassay in plasma samples collected at least 14 days post-polymerase chain reaction (PCR) confirmation of diagnosis.ResultsThirty-one non-severe COVID-19 patients were included. Nine patients (29%) had T2DM with mean HbA1c at admission of 8.3 ± 1.0%. Anti-SARS-CoV-2 antibody was estimated at a median of 16 (14–17) days post-PCR confirmation of COVID-19 diagnosis. Only three patients (10%) were seronegative, and all had T2DM. Patients with T2DM were more likely to have non-detectable anti-SARS-CoV-2 antibodies than those without DM (p = 0.019).ConclusionsCOVID-19 patients with T2DM may not undergo seroconversion even after two weeks of diagnosis. Impaired seroconversion could theoretically increase the risk of reinfections in patients with DM. However, the finding requires validation in large-scale studies involving serial estimations of anti-SARS-CoV-2 antibodies in patients with and without DM.  相似文献   
70.
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