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   1444篇
  免费   115篇
  国内免费   29篇
耳鼻咽喉   22篇
儿科学   105篇
妇产科学   25篇
基础医学   164篇
口腔科学   81篇
临床医学   160篇
内科学   321篇
皮肤病学   32篇
神经病学   60篇
特种医学   41篇
外科学   311篇
综合类   26篇
预防医学   102篇
眼科学   21篇
药学   59篇
中国医学   3篇
肿瘤学   55篇
  2022年   22篇
  2021年   46篇
  2020年   20篇
  2019年   33篇
  2018年   24篇
  2017年   25篇
  2016年   26篇
  2015年   31篇
  2014年   41篇
  2013年   53篇
  2012年   61篇
  2011年   71篇
  2010年   54篇
  2009年   39篇
  2008年   61篇
  2007年   69篇
  2006年   59篇
  2005年   65篇
  2004年   56篇
  2003年   44篇
  2002年   49篇
  2001年   38篇
  2000年   32篇
  1999年   42篇
  1998年   32篇
  1997年   27篇
  1996年   29篇
  1995年   19篇
  1994年   24篇
  1992年   19篇
  1991年   24篇
  1990年   32篇
  1989年   19篇
  1988年   24篇
  1987年   24篇
  1986年   27篇
  1985年   14篇
  1984年   13篇
  1983年   10篇
  1981年   8篇
  1979年   18篇
  1978年   13篇
  1977年   9篇
  1976年   13篇
  1975年   11篇
  1974年   10篇
  1973年   13篇
  1972年   10篇
  1969年   15篇
  1968年   11篇
排序方式: 共有1588条查询结果,搜索用时 15 毫秒
61.
62.
The quality of mother–infant interaction during the first year may be hampered by maternal substance abuse and co-existing non-optimal factors such as psychiatric problems and difficult relational experiences. In the present study three groups of women were recruited during pregnancy: One group with substance abuse problems from residential treatment centers (n = 28), a second group from psychiatric outpatient treatment centers (n = 22), and a third group from well-baby clinics (n = 30). Four maternal optimality indexes were assessed (substance abuse, psychiatric problems, relational experiences and SES). Mother–infant interaction was observed at 3 and 12 months. The substance abuse group showed the most disturbed mother–infant interaction at 12 months. Low maternal optimality as well as impairments in maternal affective involvement at 3 months influenced negatively both on infant and dyadic affective behavior in interaction at 12 months. Long-term interventions are needed to promote affective reciprocity among mother–baby pairs with low optimality.  相似文献   
63.
64.
Efficient derivation of neural cells from human embryonic stem cells (hESCs) remains an unmet need for the treatment of neurological disorders. The limiting factors for current methods include being labor-intensive, time-consuming and expensive. In this study, we hypothesize that the substrate topography, with optimal geometry and dimension, can modulate the neural fate of hESCs and enhance the efficiency of differentiation. A multi-architectural chip (MARC) containing fields of topographies varying in geometry and dimension was developed to facilitate high-throughput analysis of topography-induced neural differentiation in vitro. The hESCs were subjected to “direct differentiation”, in which small clumps of undifferentiated hESCs were cultured directly without going through the stage of embryoid body formation, on the MARC with N2 and B27 supplements for 7 days. The gene and protein expression analysis indicated that the anisotropic patterns like gratings promoted neuronal differentiation of hESCs while the isotropic patterns like pillars and wells promoted the glial differentiation of hESCs. This study showed that optimal combination of topography and biochemical cues could shorten the differentiation period and allowed derivation of neurons bearing longer neurites that were aligned along the grating axis. The MARC platform would enable high-throughput screening of topographical substrates that could maximize the efficiency of neuronal differentiation from pluripotent stem cells.  相似文献   
65.
Documenta Ophthalmologica - The study reports a case with metastatic cutaneous malignant melanoma that developed Vogt–Koyanagi–Harada-like uveitis during pembrolizumab treatment. The...  相似文献   
66.
67.

Summary

Bisphosphonates reduce skeletal loss and fracture risk, but their use has been limited in patients with chronic kidney disease. This study shows skeletal benefits of zoledronic acid in an animal model of chronic kidney disease.

Introduction

Bisphosphonates are routinely used to reduce fractures but limited data exists concerning their efficacy in non-dialysis chronic kidney disease. The goal of this study was to test the hypothesis that zoledronic acid produces similar skeletal effects in normal animals and those with kidney disease.

Methods

At 25 weeks of age, normal rats were treated with a single dose of saline vehicle or 100 μg/kg of zoledronic acid while animals with kidney disease (approximately 30 % of normal kidney function) were treated with vehicle, low dose (20 μg/kg), or high dose (100 μg/kg) zoledronic acid, or calcium gluconate (3 % in the drinking water). Skeletal properties were assessed 5 weeks later using micro-computed tomography, dynamic histomorphometry, and mechanical testing.

Results

Animals with kidney disease had significantly higher trabecular bone remodeling compared to normal animals. Zoledronic acid significantly suppressed remodeling in both normal and diseased animals yet the remodeling response to zoledronic acid was no different in normal and animals with kidney disease. Animals with kidney disease had significantly lower cortical bone biomechanical properties; these were partially normalized by treatment.

Conclusions

Based on these results, we conclude that zoledronic acid produces similar amounts of remodeling suppression in animals with high turnover kidney disease as it does in normal animals, and has positive effects on select biomechanical properties that are similar in normal animals and those with chronic kidney disease.  相似文献   
68.
Background: Methylation status of the cytokine genes may play a role in the pathogenesis of inflammatory diseases, such as rheumatoid arthritis (RA) and chronic periodontitis (CP). This study was undertaken to evaluate whether the DNA methylation profile of the interleukin‐6 (IL‐6) gene promoter was unique to individuals with RA and CP. Methods: The study participants consisted of 30 patients with RA, 30 patients with CP, and 30 age‐, sex‐, and smoking status–balanced healthy controls. Genomic DNA isolated from peripheral blood was modified by sodium bisulfite and analyzed for DNA methylation levels of IL‐6 gene with direct sequencing. Levels of IL‐6 were determined by an enzyme‐linked immunosorbent assay. Results: The region of IL‐6 gene promoter from ?1200 to +27 bp was shown to contain 19 CpG motifs. The methylation levels of the CpG motif at ?74 bp were significantly lower in patients with RA and CP than those in controls (P = 0.0001). Both levels of serum IL‐6 and IL‐6 production by mononuclear cells were significantly different between individuals with and without the methylation at ?74 bp (P = 0.03). The +19 bp motif exhibited differential levels of the methylation among the groups, which was not associated with serum levels of IL‐6. The other 17 CpG motifs exhibited comparable levels of the methylation between the groups. Conclusion: These results suggest that hypomethylated status of a single CpG in the IL‐6 promoter region may lead to increased levels of serum IL‐6, implicating a role in the pathogenesis of RA and CP.  相似文献   
69.
Clinical and Experimental Nephrology - Tolvaptan (TLV) is reported to improve diuretic effects in patients with chronic kidney disease (CKD) when furosemide (FUR) is not sufficiently effective....  相似文献   
70.
Transrectal ultrasound (TRUS) guided biopsy of the prostate has been a standard diagnostic approach for prostate cancer over the past thirty years. Today, the role of TRUS biopsy is being challenged by transperineal (TP) prostate biopsy due to concerns over the safety and diagnostic yield of TRUS biopsy. TRUS biopsy still offers a convenient, reliable and accessible tool for diagnosing prostate cancer in the majority of patients. It continues to play a role in prostate cancer diagnosis, especially where hospital resource allocation is limited, including the public sector. TRUS biopsy has low rates of severe complications, although there remains room for improvement in current practice to improve the tolerability and reduce the incidence of post-biopsy infection.  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