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   411篇
  免费   27篇
  国内免费   1篇
耳鼻咽喉   3篇
儿科学   13篇
妇产科学   42篇
基础医学   42篇
口腔科学   14篇
临床医学   46篇
内科学   77篇
皮肤病学   16篇
神经病学   40篇
特种医学   11篇
外科学   28篇
综合类   16篇
一般理论   1篇
预防医学   28篇
眼科学   8篇
药学   37篇
中国医学   5篇
肿瘤学   12篇
  2023年   9篇
  2022年   18篇
  2021年   26篇
  2020年   14篇
  2019年   26篇
  2018年   27篇
  2017年   21篇
  2016年   25篇
  2015年   18篇
  2014年   28篇
  2013年   26篇
  2012年   35篇
  2011年   34篇
  2010年   15篇
  2009年   20篇
  2008年   23篇
  2007年   14篇
  2006年   11篇
  2005年   12篇
  2004年   7篇
  2003年   7篇
  1994年   1篇
  1993年   1篇
  1992年   3篇
  1991年   2篇
  1990年   4篇
  1989年   1篇
  1988年   1篇
  1987年   2篇
  1986年   2篇
  1985年   1篇
  1984年   1篇
  1979年   4篇
排序方式: 共有439条查询结果,搜索用时 0 毫秒
21.
22.
The influence of two different doses of oral naltrexone on the adverse effects and the analgesia associated with intrathecal morphine was compared in a double-blind, placebo-controlled study. Thirty-five patients undergoing cesarean section were provided postoperative analgesia by 0.25 mg intrathecal morphine. Sixty minutes later they were given 6 mg naltrexone, 3 mg naltrexone, or placebo as an oral solution. Pain relief was assessed by the Visual Analog Scale. Requirements for additional analgesics and side effects were recorded. Duration of analgesia was shorter in the 3- and 6-mg naltrexone groups than in the placebo group, 10.0 +/- 2.6, 12.4 +/- 2.6, and 19.2 +/- 4.5 h (mean +/- SEM), respectively, but values did not reach statistical significance. The incidence of pruritus and vomiting was significantly less in the 6-mg naltrexone group than in the other two groups (P less than 0.05). Somnolence was significantly less in the 3- and 6-mg naltrexone groups than in the placebo group (P less than 0.05). Naltrexone (6 mg) is an effective oral prophylactic against the pruritus and vomiting associated with intrathecal morphine for analgesia after cesarean section, but it is associated with shorter duration of analgesia.  相似文献   
23.

Background

Bearing surface wear and osteolysis are major factors limiting the durability of total hip arthroplasty (THA). Second generation annealed highly cross-linked polyethylene (HXLPE) and ceramics were introduced to THA for their excellent wear rates. However, there is little data comparing the wear rates of metal and ceramic heads on second generation HXLPE.

Methods

Sixty patients who received a noncemented THA with a 32- or 36-mm delta ceramic head were matched with 60 THAs with a 32- or 36-mm metal head based on gender, head size, follow-up, and University of California, Los Angeles activity score. Linear and volumetric wear rates were measured.

Results

At mean 6-year follow-up, the mean linear wear rates were 0.012 mm/y (standard deviation [SD] 0.045; 95% confidence interval [CI] 0.001-0.024) and 0.018 mm/y (SD 0.025; 95% CI 0.012-0.025) for the ceramic and metal groups, respectively (P = .724). The mean volumetric wear rates for the ceramic and metal head groups were 11.9 (SD 43.0; 95% CI 0.7-23.0) and 17.3 (SD 23.9; 95% CI 11.1-23.4), respectively. No significant differences were detectable in either the mean linear or volumetric wear rates (P = .380 and P = .398, respectively).

Conclusion

Second generation HXLPE had low wear rates and we were unable to detect a significant difference in wear rates with 32- or 36-mm metal and ceramic heads. We believe that this is due to the excellent tribological properties of second generation HXLPE. We continue to use ceramic as standard of care because of issues of trunnionosis with metal heads.  相似文献   
24.
Addictive drugs modulate synaptic transmission in the meso‐corticolimbic system by hijacking normal adaptive forms of experience‐dependent synaptic plasticity. Psychostimulants such as METH have been shown to affect hippocampal synaptic plasticity, albeit with a less understood synaptic mechanism. METH is one of the most addictive drugs that elicit long‐term alterations in the synaptic plasticity in brain areas involved in reinforcement learning and reward processing. Dopamine transporter (DAT) is one of the main targets of METH. As a substrate for DAT, METH decreases dopamine uptake and increases dopamine efflux via the transporter in the target brain regions such as nucleus accumbens (NAc) and hippocampus. Due to cross talk between NAc and hippocampus, stimulation of NAc has been shown to alter hippocampal plasticity. In this study, we tested the hypothesis that manipulation of glutamatergic and GABA‐ergic systems in the shell‐NAc modulates METH‐induced enhancement of long term potentiation (LTP) in the hippocampus. Rats treated with METH (four injections of 5 mg/kg) exhibited enhanced LTP as compared to saline‐treated animals. Intra‐NAc infusion of muscimol (GABA receptor agonist) decreased METH‐induced enhancement of dentate gyrus (DG)‐LTP, while infusion of AP5 (NMDA receptor antagonist) prevented METH‐induced enhancement of LTP. These data support the interpretation that reducing NAc activity can ameliorate METH‐induced hippocampal LTP through a hippocampus‐NAc‐VTA circuit loop. Synapse 70:325–335, 2016 . © 2016 Wiley Periodicals, Inc.  相似文献   
25.
Background: Pain is a common complaint among patients referring to the emergency department. This study aimed at comparing the effect of fentanyl and vitamin B12 to decrease the abdominal pain in patients who are addicted to oral opium.

Methods: This study conducted a double-blind randomized clinical trial on patients addicted to oral opium during a one-year period. The effects of fentanyl and vitamin B12 were compared for the relief of abdominal pain in such patients.

Results: The 136 patients studied had a mean age of 47.77 ± 13.6 years (mean ± SD). There was a significant difference in mean pain severity at 10, 15, 30, 45, 60, and 120 min (P < .05). The mean pain severity in the fentanyl group was significant at 30 min compared to the earlier times and showed a decreasing trend in pain severity (P < .05). This decreasing trend was observed up to 120 min for the fentanyl + vitamin B12 group, which showed a significant difference between each time and the time preceding it (P < .05).

Conclusions: The proper and permanent control of abdominal pain experienced by patients addicted to oral opium is essential. The combined use of fentanyl and vitamin B12 is effective in reaching this goal.  相似文献   

26.
27.
28.
Resistance of Pseudomonas aeruginosa strains to the broad-spectrum cephalosporins may be mediated by the extended-spectrum β-lactamases (ESBLs). These enzymes are encoded by different genes located on either chromosomes or plasmids. This study aimed to investigate the prevalence of ESBLs and antimicrobial susceptibilities of P. aeruginosa isolated from burn patients in Tehran, Iran. Antimicrobial susceptibility of 170 isolates to cefpodoxime, aztreonam, ciprofloxacin, ofloxacin, ceftazidime, cefepime, imipenem, meropenem, cefotaxime, levofloxacin, piperacillin–tazobactam and ceftriaxone was determined by disc agar diffusion test. Polymerase chain reaction (PCR) amplification of the genes encoding OXA-10, PER-1 and VEB-1 was also performed. All isolates (100%) were resistant to ceftazidime, cefotaxime, cefepime and aztreonam. Imipenem and meropenem were the most effective anti-pseudomonal agents. The results revealed that 148 (87.05%) of the isolates were multidrug resistant and 67 (39.41%) of the isolates were ESBL positive. Fifty (74.62%), 33 (49.25%) and 21 (31.34%) strains among 67 ESBL-producing strains amplified blaOXA-10, blaPER-1 and blaVEB-1 respectively.  相似文献   
29.
Among the group of bioactive sphingolipids, sphingosylphosphorylcholine (SPC) has been known to induce both antiproliferative and proliferative effects depending on cell type. In the present investigation we show that SPC (1-10 microM) reduced the proliferation of FRO cells (an anaplastic thyroid carcinoma cell line) in a concentration dependent manner. The effect was pertussis toxin insensitive, and independent of phospholipase C, protein kinase C, p38 kinase, or jun kinase. In addition to inhibiting the migration of FRO cells, application of SPC induced a rapid (<10 min) rounding of the cells, which was dependent on extracellular sodium. However, DAPI staining and caspase-3 analysis could not reveal any apoptotic effects of SPC. Furthermore, when cells treated with SPC for 24h were washed and replated, they continued to grow, albeit somewhat slower than control cells. Flow cytometry analysis revealed a significant increase in the population of cells in the G2-M phase, and a reduction in S phase. SPC reduced the phosphorylation of Akt with about 50% and evoked a substantial decrease in the amount of phosphorylated mitogen-activated protein (MAP) kinase. In cells treated with the PI3 kinase inhibitor wortmannin, both migration and proliferation were inhibited, as well as the amount of phosphorylated MAP kinase. Treatment of the cells with either SPC or wortmannin increased the levels of p21, but decreased that of cyclin B1 and Cdc2. Taken together, SPC is an effective suppressor of thyroid cancer cell proliferation and migration, and this effect is, in part, mediated by inhibition of both the PI3K-Akt and the MAP kinase signalling pathways.  相似文献   
30.
This study examined the clinical validity of a Persian language version of the Automatic Thoughts Questionnaire (ATQ-Persian). We hypothesized that patients with major depression can be clearly distinguished from non-patient members of general population regarding both frequency of negative thoughts (ATQ-F) and degree of belief in these thoughts (ATQ-B). To test this hypothesis, we used discriminant function analysis in a group of 30 female patients with major depression and 30 female non-patient volunteers. ATQ-F and ATQ-B discriminated the large majority of depressed patients from non-patient volunteers and were correlated with the severity of depression as measured by scores on the Beck Depression Inventory-second edition. The data provide preliminary evidence for clinical validity and utility of ATQ-Persian.  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