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   4442篇
  免费   238篇
  国内免费   28篇
耳鼻咽喉   23篇
儿科学   82篇
妇产科学   96篇
基础医学   556篇
口腔科学   116篇
临床医学   388篇
内科学   958篇
皮肤病学   118篇
神经病学   604篇
特种医学   192篇
外科学   721篇
综合类   9篇
预防医学   136篇
眼科学   37篇
药学   285篇
中国医学   8篇
肿瘤学   379篇
  2023年   33篇
  2022年   84篇
  2021年   159篇
  2020年   94篇
  2019年   108篇
  2018年   137篇
  2017年   120篇
  2016年   131篇
  2015年   137篇
  2014年   205篇
  2013年   248篇
  2012年   344篇
  2011年   334篇
  2010年   207篇
  2009年   182篇
  2008年   290篇
  2007年   268篇
  2006年   213篇
  2005年   243篇
  2004年   222篇
  2003年   220篇
  2002年   156篇
  2001年   51篇
  2000年   66篇
  1999年   40篇
  1998年   30篇
  1997年   17篇
  1996年   16篇
  1995年   16篇
  1994年   8篇
  1993年   9篇
  1992年   26篇
  1991年   30篇
  1990年   28篇
  1989年   21篇
  1988年   24篇
  1987年   15篇
  1986年   14篇
  1985年   14篇
  1984年   12篇
  1983年   9篇
  1981年   6篇
  1979年   18篇
  1976年   7篇
  1975年   9篇
  1974年   13篇
  1973年   9篇
  1972年   9篇
  1971年   10篇
  1967年   9篇
排序方式: 共有4708条查询结果,搜索用时 15 毫秒
1.
2.
3.
Ocotea quixos essential oil was shown to possess significant inhibitory activity of platelet aggregation and clot retraction in rodent plasma. This study is aimed at fully characterizing the antiplatelet activity of the whole essential oil and its main components trans-cinnamaldehyde and methyl cinnamate also in human plasma, at investigating the mechanism underlying such activity and at evaluating the potential antithrombotic activity of subacute treatment of mice with Ocotea essential oil. In vitro Ocotea essential oil and trans-cinnamaldehyde inhibited arachidonic acid-, U46619-, ADP-, phorbol12-myristate13-alcetate-, collagen-induced platelet aggregation and thrombin-induced clot retraction in human and rodent plasma; Ocotea oil and trans-cinnamaldehyde competitively antagonized contractions induced by thromboxane A2 receptor agonist U46619 in rat isolated aortic ring (K(B) = 18 and 3.2 microg ml(-1), respectively). In vivo Ocotea oil, orally administered in a subacute treatment (30-100 mg kg(-1) day(-1) for 5 days) to mice, prevented acute thrombosis induced by collagen-epinephrine intravenous injection. This antithrombotic activity was not accompanied by pro-haemorragic side effect, as detected by the inactivity in bleeding test, thus showing a favourable safety profile compared to the conventional antiplatelet agent, acetylsalicylic acid. Present findings indicate that Ocotea essential oil possesses potent and safe antithrombotic activity attributable to its antiplatelet and vasorelaxant effects. The main constituent trans-cinnamaldehyde seems to be the primary responsible for this activity through a putative mechanism involving the inhibition of thromboxane A2 receptors.  相似文献   
4.
5.
Summary The effect of nifedipine 40 mg·day–1 for 3 months on glucose tolerance, insulin and C-peptide secretion after an oral glucose tolerance test (OGTT), intra-venous glucose tolerance test (IVGTT) and glucagon stimulatory test, has been studied in 8 moderately hypertensive women suffering from non-insulin dependent diabetes mellitus (NIDDM).No significant variation in glucose metabolism was noted after nifedipine treatment, except for a slight improvement in insulin secretion after OGTT at the end of the study. There was an increase in cholesterol as a collateral effect.  相似文献   
6.
BACKGROUND: Pravastatin and simvastatin prolong survival and reduce transplant-related coronary vasculopathy, although low-density lipoprotein (LDL) lowering with these agents is only modest. The objective of this study was to assess the safety of moderate dose atorvastatin and its efficacy when prior treatment with another statin had failed to lower LDL to < 100 mg/dl. METHODS: Data from 185 patients were retrospectively evaluated for adverse events, duration of exposure (person-days), and the mean atorvastatin dose exposure. Changes in lipid parameters, and prednisone and cyclosporine doses were determined. RESULTS: Safety: 48 patients received atorvastatin for 24,240 person-days at a mean dose exposure of 21 +/- 10 mg. Rhabdomyolysis, myositis, myalgias, and hepatotoxicity occurred in 0, 2, 2, and 0 patients, respectively. All events occurred at the 10-mg dose, within the first 3 months, and were rapidly reversible with atorvastatin discontinuation. Efficacy: Thirty-four patients evaluable for efficacy analyses had a pre-atorvastatin LDL of 145 +/- 38 mg/dl on the following statins: pravastatin (n = 30, 40 +/- 0mg), fluvastatin (n = 3, 33 +/- 12 mg), simvastatin (n = 1, 40 mg). After atorvastatin (21 +/- 9 mg/day) for 133 +/- 67 days, LDL was reduced to 97 +/- 24 mg/dl (relative reduction 31 +/- 20%, p < 0.0001). At the end of the observation period (418 +/- 229 days, atorvastatin final dose 24 +/- 14 mg/day), LDL was further decreased to 88 +/- 23 mg (relative reduction 37 +/- 17%, p < 0.0001). CONCLUSION: Atorvastatin, when used at moderate doses and with close biochemical and clinical monitoring, appears to be safe and is effective in aggressively lowering LDL in heart transplant recipients when treatment with other statins has failed to achieve LDL goals.  相似文献   
7.
8.
Summary:  Purpose: Psychogenic nonepileptic seizures (PNES) are episodes that may resemble epileptic seizures (ES) but are not associated with abnormal electrical discharges in the brain. Video-EEG recording of a typical episode is considered the best diagnostic tool available. PNES are, however, also documented in patients with epilepsy (PNES/ES). The purpose of this study was to assess this comorbid population, focusing on the differences between patients with PNES/ES and patients with PNES alone.
Methods: We reviewed 110 PNES episodes, occurring spontaneously or induced by means of suggestion techniques, recorded in our video-EEG laboratory over a period of eight years. We identified two subgroups of patients, consisting of 85 PNES cases and 25 PNES/ES cases, and assessed any differences in their characteristics by reviewing a number of variables (age, sex, clinical features, antiepileptic therapy, age of onset, time to diagnosis, pathological history, and length of follow-up).
Results: The comparison between the two subgroups revealed that PNES/ES patients displayed some statistically significant differences when compared with PNES alone patients, i.e., younger age, a higher percentage of spontaneously activated events, a shorter disease duration, a longer time to PNES diagnosis, and a lower percentage lost at follow-up.
Conclusions: This study confirms that PNES is a common, though probably underestimated, occurrence in epilepsy services. Our results shed light on some different characteristics between PNES and PNES/ES patients.  相似文献   
9.
PURPOSE: To determine the independent relationship between leukoreduced platelet transfusions and adverse events in cardiac surgery. METHODS: In this observational study, detailed baseline and perioperative data were prospectively collected on consecutive patients who underwent cardiac surgery at a single institution from 1999 to 2004. The independent associations of platelet transfusion with clinical outcomes (low output syndrome, myocardial infarction, stroke, renal failure, sepsis, and death) were determined by multivariable logistic regression analysis and propensity score case-control analysis. RESULTS: Of the 11,459 patients analyzed, 2,174 (19%) received (leukoreduced) platelets - 1,408 received 5 U, 471 received 10 U, 140 received 15 U, and 155 received 20 or more units. Although all measured adverse event rates were higher in those who received platelets, in neither the logistic regression analyses nor the propensity score analyses was there any association between platelet transfusion and any of the adverse events. CONCLUSIONS: Transfusion of leukoreduced platelets in cardiac surgery is not associated with adverse clinical outcomes when adjustments are made for important confounders.  相似文献   
10.
Summary An unusual case of chronic myelocytic leukemia (CML) is described that presented leukocytosis at onset (720×109/l), symptoms of stasis, organomegaly, and a conspicuous infiltration of leukemic cells from the pelvis to the right popliteal cavity. As initial therapy and in addition to chemotherapy, six therapeutic leukapheresis treatments (TL) were performed and the patient showed dramatic symptomatic improvement with reduction in leukocytosis (97×109/l), organomegaly, and tissue infiltration.  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