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   1499篇
  免费   92篇
  国内免费   7篇
耳鼻咽喉   9篇
儿科学   44篇
妇产科学   8篇
基础医学   182篇
口腔科学   53篇
临床医学   115篇
内科学   206篇
皮肤病学   71篇
神经病学   177篇
特种医学   134篇
外科学   116篇
综合类   43篇
预防医学   83篇
眼科学   16篇
药学   272篇
中国医学   1篇
肿瘤学   68篇
  2021年   25篇
  2018年   10篇
  2016年   19篇
  2015年   22篇
  2014年   22篇
  2013年   53篇
  2012年   53篇
  2011年   41篇
  2010年   40篇
  2009年   43篇
  2008年   44篇
  2007年   42篇
  2006年   49篇
  2005年   36篇
  2004年   37篇
  2003年   43篇
  2002年   42篇
  2001年   54篇
  2000年   44篇
  1999年   50篇
  1998年   53篇
  1997年   43篇
  1996年   32篇
  1995年   27篇
  1994年   35篇
  1993年   38篇
  1992年   54篇
  1991年   25篇
  1990年   29篇
  1989年   35篇
  1988年   36篇
  1987年   34篇
  1986年   41篇
  1985年   27篇
  1984年   18篇
  1983年   22篇
  1982年   21篇
  1981年   18篇
  1980年   23篇
  1979年   9篇
  1978年   12篇
  1977年   15篇
  1976年   14篇
  1975年   10篇
  1974年   13篇
  1973年   22篇
  1972年   22篇
  1971年   12篇
  1970年   16篇
  1967年   10篇
排序方式: 共有1598条查询结果,搜索用时 10 毫秒
21.
Besides the use of autologous bone grafting several osteoconductive and osteoinductive methods have been reported to improve bone healing. However, persistent non‐union occurs in a considerable number of cases and compromised angiogenesis is suspected to impede bone regeneration. Hyperbaric oxygen therapy (HBO) improves angiogenesis. This study evaluates the effects of HBO on bone defects treated with autologous bone grafting in a bone defect model in rabbits. Twenty‐four New‐Zealand White Rabbits were subjected to a unilateral critical sized diaphyseal radius bone defect and treated with autologous cancellous bone transplantation. The study groups were exposed to an additional HBO treatment regimen. Bone regeneration was evaluated radiologically and histologically at 3 and 6 weeks, angiogenesis was assessed by immunohistochemistry at three and six weeks. The additional administration of HBO resulted in a significantly increased new bone formation and angiogenesis compared to the sole treatment with autologous bone grafting. These results were apparent after three and six weeks of treatment. The addition of HBO therapy to autologous bone grafts leads to significantly improved bone regeneration. The increase in angiogenesis observed could play a crucial role for the results observed. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:513–520, 2015.  相似文献   
22.
23.
OBJECTIVE: Nocturnal enuresis is a common pediatric problem, the etiology of which is unclear. In recent years, various studies have been published stating that children with nocturnal enuresis exhibit growth and skeletal maturation retardation. METHODS: In this cross-sectional study, we included 27 patients (16 boys, 11 girls) between the ages of 6 and 14 years who had presented with primary nocturnal enuresis (PNE) complaints. We included in the evaluation 19 healthy subjects (12 boys, 7 girls), who were the siblings of the children with PNE, as the control group. RESULTS: The patients in both groups were similar in chronological age, bone age, height and weight, with no significant difference between groups (P>0.05). CONCLUSION: The two groups in our study consisted of the same genetic background. Thus, our results were found to be different from the previous studies. We have concluded that there is no direct relationship between enuresis nocturnal and skeletal maturation.  相似文献   
24.
Subcutaneous fat necrosis of the newborn is an uncommon but distinctive condition which appears in the first six weeks of life, associated with variable degrees of hypercalcaemia and which resolves spontaneously over months. We report a case of subcutaneous fat necrosis of the newborn following perinatal distress and complicated by thrombocytopenia and hypercalcaemia.  相似文献   
25.
PURPOSE: This study characterizes the effects of blepharoplasty on blink dynamics in subjects with dermatochalasis. The authors evaluate the hypothesis that orbicularis oculi removal and the consequent alterations in blink are potentially harmful consequences of blepharoplasty. METHODS: Sixteen patients were studied, before and after laser blepharoplasty, by a modified scleral search coil technique. Changes in lid position during blinks were recorded before surgery as well as 2 months, and 1 year postoperatively. Off-line analyses assessed blink down-phase amplitude, peak velocity, duration, and main sequence (peak velocity versus amplitude) relationships. RESULTS: Despite muscle resection, there was no significant compromise of mean blink down-phase amplitude, peak velocity, or main sequence following blepharoplasty. Mean blink duration was likewise unchanged at either follow-up session from the preoperative state. Our data show that upper lid blepharoplasty does not cause any lasting decrement in lid function in blinking. CONCLUSIONS: Blepharoplasty includes resection of a portion of the orbicularis oculi. It appears unlikely that the purposeful resection of preseptal portion of the orbicularis oculi that accompanies blepharoplasty is responsible for any functional complications such as dry eye.  相似文献   
26.
27.
Recently, a variety of growth factor-dependent subclones of the murine interleukin-3 (IL-3)-dependent cell line 32D have been isolated. These subclones include those dependent for growth on erythropoietin (Epo) (32D Epo), granulocyte-macrophage colony-stimulating factor (GM-CSF) (32D GM), or granulocyte colony-stimulating factor (G-CSF) (32D G). 32D Epo1.1 is a revertant of 32D Epo and is capable of growing in IL-3. These cell lines express the differentiation program appropriate to the specific growth factor and depend on the growth factors not only for proliferation but also for survival. To determine how the signal for proliferation is triggered by various growth factors, we examined the DNA histograms and the expression of cell cycle-specific genes in the different cell lines. The cell cycle-specific genes analyzed were myc (early G1), myb (late G1), and the structural genes for the calcium- binding protein 2A9 (middle G1) and histone H3 (G1-S boundary). The DNA histogram analysis of cells in the logarithmic phase of growth showed that approximately 40% of 32D, 32D GM, 32D G, and 32D Epo1.1 (growing in IL-3) were cells with a 2N DNA content (and therefore in G0/G1), and another 40% have a DNA content intermediate between 2N and 4N (in S phase). In contrast, 32D Epo and 32D Epo1.1 (growing in Epo) had fewer cells in the G0/G1 phase of the cell cycle compared with the number of cells that were in the S phase (19% to 31% v 69% to 78%, respectively). Because all the cell lines have comparable doubling times (15 to 18 hours), the cell distribution among the phases of the cell cycle is proportional to the length of the phase. Therefore, cells growing in IL- 3 (32D and 32D Epo1.1), GM-CSF (32D GM), or G-CSF (32D G) progress along the cycle in a manner typical of previously reported nontransformed cell lines. In contrast, cells growing in Epo (32D Epo or 32D Epo1.1) spend relatively less time in G0/G1 and correspondingly more time in S. These data were confirmed by the analysis of the tritiated thymidine (3H-TdR) suicide rate and of the expression of cell cycle-specific genes. The 32D and 32D Epo1.1 cells growing in IL-3 had a suicide rate of congruent to 50%, whereas the suicide rate of 32D Epo and 32D Epo1.1 growing in Epo was higher than 75%.(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   
28.
29.
30.
BACKGROUND: Neurotransmission mediated via opioid and dopamine receptors is believed to be involved in the reinforcing and/or rewarding effects of ethanol consumption. We previously examined the effect of ethanol consumption (and naltrexone treatment, used clinically to treat alcoholism) on micro-opioid receptor density. We describe here the effect of free-choice ethanol consumption and naltrexone treatment on preproenkephalin, preprodynorphin, and dopamine D1 and D2 receptor mRNA expression in the central nervous system. METHODS: Fawn-hooded rats were given continual free-choice access to a 5% ethanol solution or water (4 weeks) followed by 2 weeks of water alone. At the end of this abstinence period, osmotic minipumps were implanted subcutaneously to deliver saline (n = 4) or naltrexone (n = 4; 8.4 mg/kg/day for 4 weeks). After recovery from surgery, the rats again were given access to 5% ethanol under the same free-choice conditions (4 weeks). A third group of age-matched controls drank only water during the behavioral trial. At the end of the behavioral trial, the rats were decapitated, and a quantitative examination of peptide precursor mRNAs was made by using in situ hybridization histochemistry. RESULTS: Naltrexone treatment significantly decreased preprodynorphin expression in the nucleus accumbens, but neither naltrexone treatment nor ethanol consumption significantly affected dopamine D1 and D2 receptor mRNA expression. In contrast, ethanol consumption increased preproenkephalin mRNA in the central and intercalated nuclei of the amygdala but decreased preproenkephalin mRNA in the nucleus accumbens and olfactory tubercle. The decreased level of preproenkephalin mRNA in the nucleus accumbens may reflect a neuroadaptive response to increased release of dopamine, whereas the increased level of preproenkephalin mRNA in the central nucleus of the amygdala may be associated with an anxiolytic effect of ethanol consumption. CONCLUSIONS: The data support the putative role of opioid peptides in the effects of ethanol and suggest that the nucleus accumbens and central nucleus of the amygdala are loci for the reinforcing effects of ethanol.  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