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   2659篇
  免费   171篇
  国内免费   8篇
耳鼻咽喉   18篇
儿科学   80篇
妇产科学   12篇
基础医学   278篇
口腔科学   47篇
临床医学   357篇
内科学   504篇
皮肤病学   20篇
神经病学   236篇
特种医学   125篇
外国民族医学   1篇
外科学   284篇
综合类   40篇
一般理论   2篇
预防医学   405篇
眼科学   49篇
药学   238篇
肿瘤学   142篇
  2023年   9篇
  2022年   10篇
  2021年   38篇
  2020年   29篇
  2019年   42篇
  2018年   42篇
  2017年   41篇
  2016年   47篇
  2015年   57篇
  2014年   72篇
  2013年   143篇
  2012年   194篇
  2011年   231篇
  2010年   109篇
  2009年   115篇
  2008年   162篇
  2007年   178篇
  2006年   185篇
  2005年   211篇
  2004年   202篇
  2003年   183篇
  2002年   173篇
  2001年   24篇
  2000年   23篇
  1999年   28篇
  1998年   33篇
  1997年   28篇
  1996年   15篇
  1995年   13篇
  1994年   13篇
  1993年   26篇
  1992年   17篇
  1991年   16篇
  1990年   20篇
  1989年   10篇
  1988年   6篇
  1987年   5篇
  1986年   9篇
  1985年   7篇
  1984年   8篇
  1983年   3篇
  1982年   14篇
  1981年   6篇
  1980年   9篇
  1979年   5篇
  1978年   3篇
  1977年   3篇
  1969年   3篇
  1964年   2篇
  1960年   2篇
排序方式: 共有2838条查询结果,搜索用时 493 毫秒
91.
Background and aims: In order to assess the role played by tubular epithelial cells (TEC) and interstitial vascular endothelial cells (VEC) in interstitial fibrogenesis in human glomerulonephritis, we studied the expression of markers of activated fibroblasts (α-smooth muscle actin (αSMA) and vimentin (Vim)) and of the transforming growth factor β (TGFβ), at the level of these cells. Methods: We studied retrospectively 41 renal biopsies from patients with primary and secondary glomerulonephritis [24 males, 17 females, mean age 45.5?±?12.9?years]. Immunohistochemistry using monoclonal antibodies (SMA, Vim, TGFβ) was assessed using a semiquantitative score, that was correlated with biological and histological data (quantified using a scoring system in order to assess active-inflammatory and chronic–sclerotic/fibrotic lesions). Results: The presence of SMA and Vim as markers of myofibroblasts was found in TECs and VECs. TEC Vim expression correlated with interstitial Vim expression (r?=?0.38; p?=?0.008), interstitial infiltrate (r?=?0.31; p?=?0.027), interstitial fibrosis (R?=?0.25; p?=?0.042), GFR (r?=??0.35; p?=?0.016), SMA (r?=??0.42; p?=?0.015), TGFβ (r?=?0.25; p?=?0.046), and hemoglobin (r?=??0.55; p?r?=??0.32; p?=?0.023) and interstitial fibrosis (r?=??0.34; p?=?0.017). Conclusion: Our study reflects the complexity of the involvement of VEC and mainly of TEC in fibrosis. The expression of mesenchymal markers at the tubular cell level (especially Vim) correlates with histological interstitial changes, with the decrease of renal function and more strongly with anemia.  相似文献   
92.
The aim of this cross‐sectional study was to analyze the incidence of incisional hernia after liver transplantation (LT), to determine potential risk factors for their development, and to assess their impact on health‐related quality of life (HRQoL). Patients who underwent LT through a J‐shaped incision with a minimum follow‐up of three months were included. Follow‐up was conducted at the outpatient clinic. Short Form 36 (SF‐36) and body image questionnaire (BIQ) were used for the assessment of HRQoL. A total of 140 patients was evaluated. The mean follow‐up period was 33 (SD 20) months. Sixty patients (43%) were diagnosed with an incisional hernia. Multivariate analysis revealed surgical site infection (OR 5.27, p = 0.001), advanced age (OR 1.05, p = 0.003), and prolonged ICU stay (OR 1.54, p = 0.022) to be independent risk factors for development of incisional hernia after LT. Patients with an incisional hernia experienced significantly diminished HRQoL with respect to physical, social, and mental aspects. In conclusion, patients who undergo LT exhibit a high incidence of incisional hernia, which has a considerable impact on HRQoL. Development of incisional hernia was shown to be related to surgical site infection, advanced age, and prolonged ICU stay.  相似文献   
93.
Twin blood group chimerism seems to be very rare in humans. The 30–40 previously reported cases usually were found by mere coincidence during routine blood grouping in hospitals or blood banks. Usually in these cases frank blood group mixtures of, for example, 50/50%, 25/75%, or 5/95% at most were seen. Smaller percentages are very difficult to notice during routine work-up. Using a sensitive fluorescence technique (sensitivity >0.01%) we detected blood group chimerism in 32/415 (8%) twin pairs and 12/57 (21%) triplet pairs, respectively, which is a higher incidence than reported previously. © 1996 Wiley-Liss, Inc.  相似文献   
94.
The recent emergence and circulation of the A/ASIA/G-VII (A/G-VII) lineage of foot-and-mouth disease virus (FMDV) in the Middle East has resulted in the development of homologous vaccines to ensure susceptible animals are sufficiently protected against clinical disease. However, a second serotype A lineage called A/ASIA/Iran-05 (A/IRN/05) continues to circulate in the region and it is therefore imperative to ensure vaccine strains used will protect against both lineages. In addition, for FMDV vaccine banks that usually hold a limited number of strains, it is necessary to include strains with a broad antigenic coverage. To assess the cross protective ability of an A/G-VII emergency vaccine (formulated at 43 (95% CI 8–230) PD50/dose as determined during homologous challenge), we performed a heterologous potency test according to the European Pharmacopoeia design using a field isolate from the A/IRN/05 lineage as the challenge virus. The estimated heterologous potency in this study was 2.0 (95% CI 0.4–6.0) PD50/dose, which is below the minimum potency recommended by the World Organisation for Animal Health (OIE). Furthermore, the cross-reactive antibody titres against the heterologous challenge virus were poor (≤log10 0.9), even in those cattle that had received the full dose of vaccine. The geometric mean r1-value was 0.2 (95% CI 0.03–0.8), similar to the potency ratio of 0.04 (95% CI 0.004–0.3). Vaccination decreased viraemia and virus excretion compared to the unvaccinated controls. Our results indicate that this A/G-VII vaccine does not provide sufficient protection against viruses belonging to the A/IRN/05 lineage and therefore the A/G-VII vaccine strain cannot replace the A/IRN/05 vaccine strain but could be considered an additional strain for use in vaccines and antigen banks.  相似文献   
95.
96.
97.
Purpose: Assess the effect of heart rate on diagnostic accuracy for the detection of significant coronary artery stenosis using 16-row multislice computed tomography (MSCT). Material and methods: About 120 patients (105 males; 59±11 years) with suspected coronary artery disease who underwent conventional coronary angiography (CA) and MSCT-CA were retrospectively enrolled for the study. Patients underwent a MSCT-CA (Sensation 16, Siemens, Germany), with the following protocol: collimation 16×0.75 mm, gantry rotation time 420 ms, feed/rotation 3.0 mm, kV 120, mAs 400–500. The protocol for contrast material administration was 100 ml of Iodixanol (Visipaque 320 mg l/ml, Amersham, UK) at 4 ml/s and the delay was defined with a bolus tracking technique. In all patients the mean heart rate (HR) during the scan was used as a criteria to divide the population in two groups of 60 patients each. In one group (Low HR) the 60 patients with lower heart rates, and in the other group (High HR) the patients with higher heart rates. In the two groups diagnostic accuracy (per coronary segment) for the detection of significant stenosis (≥50% lumen reduction) was evaluated in vessels ≥2 mm of diameter using quantitative CA as reference standard. The difference in diagnostic accuracy were compared with a Chi2 test and a p<0.05 was considered significant. Results: There was no significant difference between the two groups regarding age, gender, weight, mean intravascular attenuation, and calcium score. Overall 1310 (652 for Low HR and 658 for High HR) segments with 219 (105 for Low HR and 114 for High HR) significant lesions were available for the analysis. The average heart rate was 52±4HU and 63±5HU for Low HR and High HR, respectively (p<0.001). The sensitivity and specificity were 92 and 96% for Low HR and 90 and 92% for High HR (p<0.05). There were 22 vs. 44 false positives, and 8 vs. 12 false negatives in the Low HR and High HR, respectively. Conclusion: Increasing HR significantly deteriorates diagnostic accuracy in MSCT-CA.  相似文献   
98.
Conventional high‐grade osteosarcoma is the most common primary bone sarcoma, with relatively high incidence in young people. In this study we found that expression of Aven correlates inversely with metastasis‐free survival in osteosarcoma patients and is increased in metastases compared to primary tumours. Aven is an adaptor protein that has been implicated in anti‐apoptotic signalling and serves as an oncoprotein in acute lymphoblastic leukaemia. In osteosarcoma cells, silencing Aven triggered G2 cell‐cycle arrest; Chk1 protein levels were attenuated and ATR–Chk1 DNA damage response signalling in response to chemotherapy was abolished in Aven‐depleted osteosarcoma cells, while ATM, Chk2 and p53 activation remained intact. Osteosarcoma is notoriously difficult to treat with standard chemotherapy, and we examined whether pharmacological inhibition of the Aven‐controlled ATR–Chk1 response could sensitize osteosarcoma cells to genotoxic compounds. Indeed, pharmacological inhibitors targeting Chk1/Chk2 or those selective for Chk1 synergized with standard chemotherapy in 2D cultures. Likewise, in 3D extracellular matrix‐embedded cultures, Chk1 inhibition led to effective sensitization to chemotherapy. Together, these findings implicate Aven in ATR–Chk1 signalling and point towards Chk1 inhibition as a strategy to sensitize human osteosarcomas to chemotherapy. Copyright © 2015 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.  相似文献   
99.
100.
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