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   5541篇
  免费   544篇
  国内免费   87篇
耳鼻咽喉   42篇
儿科学   125篇
妇产科学   249篇
基础医学   701篇
口腔科学   65篇
临床医学   570篇
内科学   1146篇
皮肤病学   92篇
神经病学   429篇
特种医学   350篇
外科学   778篇
综合类   124篇
预防医学   320篇
眼科学   101篇
药学   401篇
中国医学   26篇
肿瘤学   653篇
  2023年   31篇
  2022年   54篇
  2021年   126篇
  2020年   98篇
  2019年   179篇
  2018年   181篇
  2017年   123篇
  2016年   141篇
  2015年   182篇
  2014年   216篇
  2013年   328篇
  2012年   385篇
  2011年   384篇
  2010年   268篇
  2009年   215篇
  2008年   298篇
  2007年   312篇
  2006年   268篇
  2005年   286篇
  2004年   259篇
  2003年   231篇
  2002年   222篇
  2001年   175篇
  2000年   148篇
  1999年   150篇
  1998年   50篇
  1997年   42篇
  1996年   36篇
  1995年   32篇
  1994年   21篇
  1993年   28篇
  1992年   83篇
  1991年   81篇
  1990年   55篇
  1989年   52篇
  1988年   54篇
  1987年   51篇
  1986年   44篇
  1985年   48篇
  1984年   41篇
  1983年   23篇
  1982年   21篇
  1981年   13篇
  1980年   13篇
  1979年   12篇
  1978年   16篇
  1977年   12篇
  1975年   12篇
  1974年   11篇
  1969年   9篇
排序方式: 共有6172条查询结果,搜索用时 31 毫秒
111.
112.
Human tumourous imaginal disc (Tid1), a human homologue of the Drosophila tumour suppressor protein Tid56, is involved in multiple intracellular signalling pathways such as apoptosis, cell proliferation, and cell survival. Here, we investigated the anti‐tumourigenic activity of Tid1 in head and neck squamous cell carcinoma (HNSCC) in vitro and in vivo. Firstly, the clinical association between Tid1 expression and progression of HNSCC was explored. It was found that expression of Tid1 was negatively associated with tumour status, recurrence, and survival prognosis using immunohistochemical analysis of primary HNSCC patient tumour tissue. Secondly, ectopic expression of Tid1 in HNSCC cells was shown to significantly inhibit cell proliferation, migration, invasion, anchorage‐independent growth, and xenotransplantation tumourigenicity. Thirdly, we showed that overexpression of Tid1 attenuated EGFR activity and blocked the activation of AKT in HNSCC cells, which are known to be involved in the regulation of survival in HNSCC cells. On the other hand, ectopic expression of constitutively active AKT greatly reduced apoptosis induced by Tid1 overexpression. Together, these findings suggest that Tid1 functions as a tumour suppressor in HNSCC tumourigenesis. Copyright © 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.  相似文献   
113.
To clarify whether fosinopril monotherapy can improve left ventricular diastolic function (LVDF) in young mildly hypertensives without hypertrophy, we studied 66 patients (pts) with diastolic blood pressure 90–100 mmHg, aged <45 years, with normal 2-dimensional echocardiography (2-D echo), and impaired DF. Impaired DF was defined as a Doppler transmitral early (E) to atrial (A) filling velocity ratio (E/A ratio) <1. Thirty-eight pts were selected for fosinopril monotherapy. Mean age was 36 years. Duration of documented hypertension was 5.4 years. Mean daily dose of fosinopril was 20 mg. Twenty-eight controls were treated with hydrochlorothiazide and hydralazine combination. Sixty-six age- and sex-matched healthy subjects served to establish normal reference values of 2-D and Doppler echo measurements. All hypertensives were treated for 30 months and re-examined 4 weeks after cessation of treatment. The fosinopril-treated group showed improvements in transmitral E (52 ± 8 cm/s, vs. 61 ± 9 cm/s, p < 0.01), A (56 ± 9 cm/s, vs. 47 ± 6 cm/s, p < 0.05), and E/A ratio (0.93 ± 0.16, vs. 1.29 ± 0.18, p < 0.01). Moreover, the early to atrial velocity-time integral ratio (1.31 ± 0.10, vs. 2.24 ± 0.10, p < 0.001) improved. The pulmonary venous flow pattern normalized after fosinopril therapy. LV mass index, relative wall thickness, LV dimension, left atrial dimension, fractional shortening, heart rate, and body mass index did not change. The hydrochlorothiazide-hydralazine combination-treated group did not show an improved diastolic function. It is concluded that long-term fosinopril monotherapy leads to an improvement of impaired LVDF in young mildly hypertensives without hypertrophy.  相似文献   
114.
115.
Metabolic acidosis is observed in 98% of patients with out-of-hospital cardiac arrest (OHCA). The longer the no-flow or low-flow duration, the more severe is the acidosis in these patients. This study explored whether blood pH in early stages of advanced life support (ALS) was an independent predictor of neurological prognosis in patients with OHCA.We retrospectively enrolled patients with OHCA from January 2012 to June 2018 in a single-medical tertiary hospital in Taiwan. Patients with OHCA whose blood gas analyses within 5 minutes after receiving ALS at the emergency department (ED) were enrolled. Patients younger than 20 years old, with cardiac arrest resulting from traumatic or circumstantial causes, with return of spontaneous circulation (ROSC) before ED arrival, lacking record of initial blood gas analysis, and with do-not-resuscitate orders were excluded. The primary outcome of this study was neurological status at hospital discharge.In total, 2034 patients with OHCA were enrolled. The majority were male (61.89%), and the average age was 67.8 ± 17.0 years. Witnessed OHCA was noted in 571 cases, cardiopulmonary resuscitation was performed before paramedic arrival in 512 (25.2%) cases, and a shockable rhythm was observed in 269 (13.2%). Blood pH from initial blood gas analysis remained an independent predictor of neurological outcome after multivariate regression.Blood pH at early stages of ALS was an independent prognostic factor of post-OHCA neurological outcome. Blood gas analysis on arrival at the ED may provide additional information about the prognosis of patients with OHCA.  相似文献   
116.
Although there are few reports regarding α‐phellandrene (α‐PA), a natural compound from Schinus molle L. essential oil, there is no report to show that α‐PA induced DNA damage and affected DNA repair associated protein expression. Herein, we investigated the effects of α‐PA on DNA damage and repair associated protein expression in murine leukemia cells. Flow cytometric assay was used to measure the effects of α‐PA on total cell viability and the results indicated that α‐PA induced cell death. Comet assay and 4,6‐diamidino‐2‐phenylindole dihydrochloride staining were used for measuring DNA damage and condensation, respectively, and the results indicated that α‐PA induced DNA damage and condensation in a concentration‐dependent manner. DNA gel electrophoresis was used to examine the DNA damage and the results showed that α‐PA induced DNA damage in WEHI‐3 cells. Western blotting assay was used to measure the changes of DNA damage and repair associated protein expression and the results indicated that α‐PA increased p‐p53, p‐H2A.X, 14‐3‐3‐σ, and MDC1 protein expression but inhibited the protein of p53, MGMT, DNA‐PK, and BRCA‐1. © 2014 Wiley Periodicals, Inc. Environ Toxicol 30: 1322–1330, 2015.  相似文献   
117.
118.
119.
Molecular basis of weak D in Taiwanese   总被引:4,自引:0,他引:4  
Two genes, RHD and RHCE, encode the antigens of the RH blood group system. The weak D phenotype is caused by many different RHD alleles encoding aberrant RhD proteins, resulting in distinct serologic phenotypes and anti-D immunization. We analyzed seven weak D phenotypes excluding Del, using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and direct sequencing methods to detect the changes of all ten RHD exons. The results show that there are four types of weak D in Taiwanese: one case each for CGG to CAG mutation at codon 10, GTG to ATG mutation at codon 174, and GTG to GAG mutation at codon 270, and four cases for GGT to GAT mutation at codon 282. In conclusion, we present the first data of a molecular basis of weak D in Taiwanese, which suggest a clinically relevant potential for anti-D immunization and may improve transfusion strategy in weak D Taiwanese patients.  相似文献   
120.

Background

Atrial fibrillation (AF) is the most common sustained arrhythmia, and pulmonary veins (PVs) play a critical role in triggering AF. Angiotensin (Ang)‐(1‐7) regulates calcium (Ca2+) homoeostasis and also plays a critical role in cardiovascular pathophysiology. However, the role of Ang‐(1‐7) in PV arrhythmogenesis remains unclear.

Materials and methods

Conventional microelectrodes, whole‐cell patch‐clamp and the fluo‐3 fluorimetric ratio technique were used to record ionic currents and intracellular Ca2+ in isolated rabbit PV preparations and in single isolated PV cardiomyocytes, before and after administration of Ang‐(1‐7).

Results

Ang (1‐7) concentration dependently (0.1, 1, 10 and 100 nmol/L) decreased PV spontaneous electrical activity. Ang‐(1‐7) (100 nmol/L) decreased the late sodium (Na+), L‐type Ca2+ and Na+‐Ca2+ exchanger currents, but did not affect the voltage‐dependent Na+ current in PV cardiomyocytes. In addition, Ang‐(1‐7) decreased intracellular Ca2+ transient and sarcoplasmic reticulum Ca2+ content in PV cardiomyocytes. A779 (a Mas receptor blocker, 3 μmol/L), L‐NAME (a NO synthesis inhibitor, 100 μmol/L) or wortmannin (a specific PI3K inhibitor, 10 nmol/L) attenuated the effects of Ang‐(1‐7) (100 nmol/L) on PV spontaneous electric activity.

Conclusion

Ang‐(1‐7) regulates PV electrophysiological characteristics and Ca2+ homoeostasis via Mas/PI3K/eNOS signalling pathway.  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