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   4579篇
  免费   176篇
  国内免费   17篇
耳鼻咽喉   113篇
儿科学   115篇
妇产科学   211篇
基础医学   524篇
口腔科学   15篇
临床医学   310篇
内科学   1306篇
皮肤病学   100篇
神经病学   282篇
特种医学   82篇
外科学   585篇
综合类   40篇
一般理论   1篇
预防医学   263篇
眼科学   69篇
药学   371篇
中国医学   4篇
肿瘤学   381篇
  2023年   23篇
  2022年   115篇
  2021年   204篇
  2020年   60篇
  2019年   92篇
  2018年   115篇
  2017年   86篇
  2016年   104篇
  2015年   122篇
  2014年   161篇
  2013年   211篇
  2012年   359篇
  2011年   409篇
  2010年   186篇
  2009年   108篇
  2008年   291篇
  2007年   359篇
  2006年   323篇
  2005年   310篇
  2004年   325篇
  2003年   328篇
  2002年   236篇
  2001年   27篇
  2000年   14篇
  1999年   21篇
  1998年   21篇
  1997年   26篇
  1996年   11篇
  1995年   15篇
  1994年   7篇
  1993年   19篇
  1992年   7篇
  1991年   2篇
  1990年   7篇
  1989年   6篇
  1988年   3篇
  1987年   3篇
  1986年   3篇
  1985年   3篇
  1984年   9篇
  1983年   3篇
  1982年   3篇
  1981年   6篇
  1980年   4篇
  1979年   3篇
  1977年   3篇
  1976年   3篇
  1974年   3篇
  1970年   2篇
  1969年   3篇
排序方式: 共有4772条查询结果,搜索用时 31 毫秒
81.
Introduction: Tumor necrosis factor (TNF) is a cytokine able to exert anti-tumor activity in various models and modes of applications. However, the exact mechanism mediating the in vivo anti-tumor effect of TNF has not yet been clarified. Materials and Methods: The effects of intratumoral injection of rat TNF into hamsters bearing Bomirski Ab amelanotic melanoma, a fast growing tumor of high metastatic potential, were tested. Subcutaneous injections of the anti-angiogenic compound TNP-470 allowed analysis of its influence on the effects of TNF administration. Results: TNF application resulted in a significant inhibition of tumor growth and changes in metastasis pattern. Accelerated hemorrhagic necrosis was also observed, indicating the effect of the cytokine on tumor vessels. Moreover, the synergistic anti-tumor effect of TNF and anti-angiogenic agent TNP-470 suggested a cooperative activity of both substances on tumor vasculature. Microscopically, the effect of TNF injections was expressed by an increase in the amount of tumor cells with nuclear pyknosis and karryorrhexis. In vitro assays indicated a direct cytotoxic effect of TNF against Ab melanoma cells, most probably as an outcome of apoptosis. Intratumoral application of TNF also caused some modulation of cytokine response in melanoma-bearing hamsters as evidenced by increased levels of IL-6 in blood serum. Conclusions: This study established Bomirski Ab melanoma as a useful model for complex analysis of the anti-tumor activity of TNF.  相似文献   
82.
Introduction: The aim of the study was to evaluate some selected parameters of the antioxidative system in patients with type 2 diabetes. Materials and Methods: Eighty-one type 2 diabetes patients took part in the study (39 patients with metabolically balanced and 42 with metabolically unbalanced diabetes). The control group consisted of 30 healthy people. The total antioxidant capacity of plasma was measured fluorometrically using phycoerythrin. To calculate the low-molecular-weight antioxidant concentration in the plasma samples, the duration of Trolox activity as a function of its concentration in the sample was measured. The activity of antioxidative enzymes in red blood cells was determined using the Misra and Fridovich method and Beers and Sizer method. Results: The total plasma antioxidant capacity and the low-molecular-weight antioxidant concentration in the group of patients with metabolically compensated type 2 diabetes were statistically significantly higher than in the group of patients with metabolically uncontrolled diabetes. The activity of antioxidative enzymes was found to be higher in the group of type 2 diabetes patients at the stage of metabolic balance. Conclusions: The obtained results confirm the thesis of glucose toxicity and intensification of oxidative stress in patients with diabetes.  相似文献   
83.

Purpose

Isolation and identification of unknown impurities of recombinant insulin lispro (produced at IBA) formed during accelerated stability testing of pharmaceutical solutions. For comparative purposes also commercially available formulations of recombinant human insulin (Humulin S®; Lilly), recombinant insulin lispro (Humalog®; Lilly), recombinant insulin aspart (NovoRapid® Penfill®; Novo Nordisk), recombinant insulin detemir (Levemir®; Novo Nordisk) and recombinant insulin glargine (Lantus®; Sanofi-Aventis) were analyzed.

Methods

The impurities of insulin analogs were isolated by RP-HPLC and identified with peptide mass fingerprinting using MALDI-TOF/TOF mass spectrometry.

Results

The identified derivatives were N-terminally truncated insulin analog impurities of decreased molecular mass of 119, 147 and 377 Da related to the original protein. The modifications resulting in a mass decrease were detected at the N-terminus of B chains of insulin lispro, insulin aspart, human insulin, insulin glargine, insulin detemir in all tested formulations. To our knowledge it is the first time that these impurities are reported.

Conclusions

The following derivatives formed by truncation of the B chain in insulin analogs were identified in pharmaceutical formulations: desPheB1-N-formyl-ValB2 derivative, desPheB1 derivative, pyroGluB4 derivative.
  相似文献   
84.

Background

Selenium is an essential element which shows protective properties against diverse harmful factors. Lithium compounds are widely used in medicine, but, in spite of undoubted beneficial effects, treatment with these compounds may lead to severe side effects, including renal, gastrointestinal, neurological, endocrine and metabolic disorders. This study was aimed at evaluating the influence of selenium and/or lithium on lithium, iron, zinc and copper content in rats’ erythrocytes as well as estimate the action of additional selenium on lithium exposure effects.

Methods

The experiment was performed on four groups of rats (six animals each): control – received saline; Li – received 2.7 mg Li/kg b.w. as lithium carbonate; Se – received 0.5 mg Se/kg b.w. as sodium selenite; Se + Li – received simultaneously 0.5 mg Se/kg b.w. and 2.7 mg Li/kg b.w. (sodium selenite and lithium carbonate). The administration was performed for three weeks, once a day by stomach tube, in form of water solutions. In erythrocytes the content of lithium, iron, zinc and copper was determined using flame atomic absorption spectroscopy.

Results

Lithium treatment insignificantly disturbed iron and zinc homeostasis as well as markedly increased lithium accumulation and copper content in rat erythrocytes. Selenium coadministration reversed those effects.

Conclusions

The beneficial effect of selenium on disturbances of studied microelements homeostasis as well as on preventing lithium accumulation in erythrocytes in Li receiving animals allows suggesting that further research on selenium application as an adjuvant in lithium therapy is worth carrying on.  相似文献   
85.

Background

Maintaining a good nutritional status during the hematopoietic cell transplantation (HCT) procedure is challenging in the pediatric population.

Methods

In a multicentric retrospective study, we compared the outcome of nutritional status and HCT-related parameters in 227 pediatric patients during and after HCT between 2005 and 2015. 112 patients received a gastrostomy before the start of HCT (GS group), and 115 did not receive a gastrostomy (NGS). Data collection was performed at HCT, 3, 6, and 12 months post-HCT.

Results

At time point of HCT the Standard Deviation Score (SDS) of weight was 0.17 in the NGS group, and 0.71 in the GS group (p = .01) Patients in the NGS group lost more weight during the first 3 months after HCT than patients in the GS group. At 12 months, patients in the NGS remained at a lower weight, while patients in the GS group slightly increased their weight. There were no differences between the groups in the incidence of acute graft-versus-host-disease (GvHD), overall survival, and non-relapse mortality. However, the number of febrile episodes requiring intravenous treatment with antibiotics, was higher in the GS group as compared to the NGS group, during the first 3 months post-HCT (p < .001).

Conclusions

Our results indicate that gastrostomy can be utilized in children undergoing HCT without any negative effects on mortality. Therefore, the use of a gastrostomy appears to be a safe option to maintain a good nutritional status during the HCT procedure.  相似文献   
86.
Tseng  William W.  Swallow  Carol J.  Strauss  Dirk C.  Bonvalot  Sylvie  Rutkowski  Piotr  Ford  Samuel J.  Gonzalez  Ricardo J.  Gladdy  Rebecca A.  Gyorki  David E.  Fairweather  Mark  Lee  Kyo Won  Albertsmeier  Markus  van Houdt  Winan J.  Fau  Magalie  Nessim  Carolyn  Grignani  Giovanni  Cardona  Kenneth  Quagliuolo  Vittorio  Grignol  Valerie  Farma  Jeffrey M.  Pennacchioli  Elisabetta  Fiore  Marco  Hayes  Andrew  Tzanis  Dimitri  Skoczylas  Jacek  Almond  Max L.  Mullinax  John E.  Johnston  Wendy  Snow  Hayden  Haas  Rick L.  Callegaro  Dario  Smith  Myles J.  Bouhadiba  Toufik  Desai  Anant  Voss  Rachel  Sanfilippo  Roberta  Jones  Robin L.  Baldini  Elizabeth H.  Wagner  Andrew J.  Catton  Charles N.  Stacchiotti  Silvia  Thway  Khin  Roland  Christina L.  Raut  Chandrajit P.  Gronchi  Alessandro 《Annals of surgical oncology》2022,29(12):7335-7348
Annals of Surgical Oncology - Surgery is the mainstay of treatment for retroperitoneal sarcoma (RPS), but local recurrence is common. Biologic behavior and recurrence patterns differ significantly...  相似文献   
87.
Cardiac allograft vasculopathy (CAV) is an increasingly important complication after cardiac transplant. We assessed the additive diagnostic benefit of quantitative plaque analysis in patients undergoing coronary computed tomography–angiography (CCTA). Consecutive patients undergoing CCTA for CAV surveillance were identified. Scans were visually interpreted for coronary stenosis. Semiautomated software was used to quantify noncalcified plaque (NCP), as well as its components. Optimal diagnostic cut‐offs for CAV, with coronary angiography as gold standard, were defined using receiver operating characteristic curves. In total, 36 scans were identified in 17 patients. CAV was present in 17 (46.0%) reference coronary angiograms, at a median of 1.9 years before CCTA. Median NCP (147 vs 58, P < .001), low‐density NCP (median 4.5 vs 0.9, P = .003), fibrous plaque (median 76.1 vs 31.1, P = .003), and fibrofatty plaque (median 63.6 vs 27.6, P < .001) volumes were higher in patients with CAV, whereas calcified plaque was not (median 0.0 vs 0.0, P = .510). Visual assessment of CCTA alone was 70.6% sensitive and 100% specific for CAV. The addition of total NCP volume increased sensitivity to 82.4% while maintaining 100% specificity. NCP volume is significantly higher in patients with CAV. The addition of quantitative analysis to visual interpretation improves the sensitivity for detecting CAV without reducing specificity.  相似文献   
88.
Neurosurgical Review - Brachial plexus injuries are among the rarest but at the same time the most severe complications of shoulder dislocation. The symptoms range from transient weakening or...  相似文献   
89.
90.
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