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   4169篇
  免费   247篇
  国内免费   22篇
耳鼻咽喉   46篇
儿科学   128篇
妇产科学   58篇
基础医学   672篇
口腔科学   428篇
临床医学   288篇
内科学   918篇
皮肤病学   105篇
神经病学   357篇
特种医学   41篇
外科学   404篇
综合类   14篇
预防医学   398篇
眼科学   60篇
药学   302篇
中国医学   22篇
肿瘤学   197篇
  2024年   5篇
  2023年   45篇
  2022年   58篇
  2021年   150篇
  2020年   112篇
  2019年   150篇
  2018年   148篇
  2017年   123篇
  2016年   112篇
  2015年   157篇
  2014年   200篇
  2013年   239篇
  2012年   360篇
  2011年   431篇
  2010年   254篇
  2009年   199篇
  2008年   316篇
  2007年   278篇
  2006年   224篇
  2005年   217篇
  2004年   196篇
  2003年   164篇
  2002年   122篇
  2001年   12篇
  2000年   14篇
  1999年   18篇
  1998年   22篇
  1997年   14篇
  1996年   12篇
  1995年   12篇
  1994年   9篇
  1993年   9篇
  1992年   6篇
  1991年   5篇
  1990年   7篇
  1989年   5篇
  1988年   6篇
  1987年   2篇
  1985年   3篇
  1984年   2篇
  1983年   3篇
  1982年   5篇
  1981年   1篇
  1980年   2篇
  1979年   2篇
  1977年   3篇
  1976年   1篇
  1974年   1篇
  1973年   1篇
  1970年   1篇
排序方式: 共有4438条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.

Background  

Due to marginalization, trafficking violence, conflicts with the police and organic and social psychological problems associated with the drug, crack is one of the most devastating drugs currently in use. However, there is evidence that some users manage to stay alive and active while using crack cocaine for many years, despite the numerous adversities and risks involved with this behavior. In this context, the aim of the present study was to identify the strategies and tactics developed by crack users to deal with the risks associated with the culture of use by examining the survival strategies employed by long-term users.  相似文献   
6.
PURPOSE: Current treatment for febrile neutropenia (FN) includes hospitalization for evaluation, empiric broad-spectrum antibiotics, and other supportive care. Clinical trials have reported conflicting results when studying whether the colony-stimulating factors (CSFs) improve outcomes in patients with FN. This Cochrane Collaboration review was undertaken to further evaluate the safety and efficacy of the CSFs in patients with FN. METHODS: An exhaustive literature search was undertaken including major electronic databases (CANCERLIT, EMBASE, LILACS, MEDLINE, SCI, and the Cochrane Controlled Trials Register). All randomized controlled trials that compare CSFs plus antibiotics versus antibiotics alone for the treatment of established FN in adults and children were sought. A meta-analysis of the selected studies was performed. RESULTS: More than 8,000 references were screened, with 13 studies meeting eligibility criteria for inclusion. The overall mortality was not influenced significantly by the use of CSF (odds ratio [OR] = 0.68; 95% CI, 0.43 to 1.08; P = .1). A marginally significant result was obtained for the use of CSF in reducing infection-related mortality (OR = 0.51; 95% CI, 0.26 to 1.00; P = .05). Patients treated with CSFs had a shorter length of hospitalization (hazard ratio [HR] = 0.63; 95% CI, 0.49 to 0.82; P = .0006) and a shorter time to neutrophil recovery (HR = 0.32; 95% CI, 0.23 to 0.46; P < .00001). CONCLUSION: The use of the CSFs in patients with established FN caused by cancer chemotherapy reduces the amount of time spent in hospital and the neutrophil recovery period. The possible influence of the CSFs on infection-related mortality requires further investigation.  相似文献   
7.
8.
We compared the activities of azithromycin, erythromycin, and penicillin G in a mouse model of systemic infection and septic arthritis induced by type IV group B streptococci (GBS). The in vitro and in vivo efficacy data for these drugs were analyzed relative to the pharmacokinetics of the drugs in sera, joints, and kidneys. Adult CD-1 mice were infected intravenously with 10(7) CFU of type IV GBS. Intraperitoneal drug administration was initiated with different dose regimens at different times after infection. A single dose of azithromycin (100 mg/kg) strongly reduced the incidence of articular lesions with respect to that with erythromycin or penicillin G. Treatment with azithromycin (three intraperitoneal administrations of 50 mg/kg at 12-h intervals) resulted in the complete prevention of arthritis. In contrast, erythromycin was poorly effective and penicillin G was effective only if inoculated 30 min after infection and at high doses (400,000 or 600,000 IU/kg). Furthermore, azithromycin was able to cure about 70% of the mice when administered 7, 8, and 9 days after GBS infection. Azithromycin was much more active than erythromycin and penicillin G with respect to bacterial killing in the joints and kidneys. In fact, cultures from these tissues were always negative no matter what treatment schedule was employed. The pharmacokinetics of azithromycin account for its superior in vivo efficacy against type IV GBS. A longer half-life and higher levels of this drug in serum and tissues with respect to those for erythromycin or penicillin G were achieved. The high affinity of azithromycin for the joints strongly supports its potential value for therapy of septic arthritis, which is a severe and frequent clinical manifestation of GBS infection.  相似文献   
9.
Insomnia in psychiatric patients is frequently underestimated in clinical practice. Usually drugs are prescribed for the treatment of this disorder but non-pharmacological intervention can be successfully used. The present study aimed at evaluating the efficacy of a two-session psychoeducational intervention in improving persistent non-organic insomnia and reducing the administration of PRN therapy in severely mentally ill patients. A pre-post study was performed on 36 psychiatric patients admitted to a residential psychiatric unit. The Nocturnal Sleep Onset Scale (NSOS) and Daytime Sleepiness Scale (DSS), the sleep onset latency, the time awake after sleep onset and the numbers of awakenings were gathered 2 weeks before the intervention (T0), immediately prior the intervention (T1), 2 weeks after the last session of the intervention (T2) and a 3-month follow-up (T3). The total number of administrations of PRN therapy from T0 to T1 and from T1 to T2 were also examined. A significant reduction was shown on the NSOS, the sleep onset latency and in the time awake after sleep onset from T1 to T2 and from T1 to T3, while no significant difference was found between T0 and T1. A significant decrease on the mean number of administrations of PRN therapy was also found between 15 days before the intervention (T0-T1) and 15 days after intervention (T1-T2). The initial results of this study seems to suggest the possible efficacy of a short-term psychoeducational intervention on improving persistent non-organic insomnia in severely mentally ill patients. Further control studies are necessary to confirm these findings.  相似文献   
10.
Abstract –  The main objective of this study was to assess the epidemiology of traumatic dental injuries (TDI) to the primary teeth of preschool children and second, to investigate whether TDI were related to anterior open bite and, third, whether TDI are related to socio-economic circumstances in an urban Brazilian population. A clinical examination was performed during the National Day of Children's Vaccination. TDI were classified according to the modified classification proposed by Ellis. In addition to those criteria the presence of tooth discoloration was recorded. An interview was carried out with mothers or guardians. The data collected included mother's level of education and living conditions. The prevalence of TDI was 9.4%. The maxillary central incisors were the most affected teeth. Most children with a TDI experienced traumatic injuries to one tooth (6.3%), while 2.8% had two and 0.4% had three traumatized teeth. The most common crown fracture was in enamel only (68.8%), followed by crown fracture of enamel and dentin (13.8%). Missing teeth following trauma occurred in 10.9% of those with TDI. The prevalence of tooth discoloration was 5.1%. Children with anterior open bite had twice the level the level of TDI compared to those with normal occlusions ( P  = 0.001). Socio-economic factors were not statistically significantly associated with the occurrence of TDI. The prevalence of dental injuries in Brazilian preschool children was low. Children with anterior open bite experienced more dental injuries. Neither of the indicators of socio-economic status was related to the prevalence of TDI.  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