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   44000篇
  免费   4193篇
  国内免费   1529篇
耳鼻咽喉   99篇
儿科学   609篇
妇产科学   950篇
基础医学   6511篇
口腔科学   1317篇
临床医学   4559篇
内科学   6230篇
皮肤病学   326篇
神经病学   6277篇
特种医学   1039篇
外科学   4764篇
综合类   4348篇
现状与发展   2篇
一般理论   1篇
预防医学   3324篇
眼科学   526篇
药学   5912篇
  17篇
中国医学   1868篇
肿瘤学   1043篇
  2024年   127篇
  2023年   782篇
  2022年   1210篇
  2021年   2196篇
  2020年   2073篇
  2019年   1772篇
  2018年   1718篇
  2017年   1927篇
  2016年   2038篇
  2015年   1962篇
  2014年   2936篇
  2013年   4006篇
  2012年   2448篇
  2011年   2836篇
  2010年   2211篇
  2009年   2339篇
  2008年   2421篇
  2007年   2034篇
  2006年   1878篇
  2005年   1433篇
  2004年   1354篇
  2003年   1172篇
  2002年   908篇
  2001年   787篇
  2000年   662篇
  1999年   531篇
  1998年   505篇
  1997年   445篇
  1996年   390篇
  1995年   274篇
  1994年   257篇
  1993年   207篇
  1992年   232篇
  1991年   201篇
  1990年   197篇
  1989年   179篇
  1988年   147篇
  1987年   114篇
  1986年   117篇
  1985年   144篇
  1984年   118篇
  1983年   69篇
  1982年   76篇
  1981年   62篇
  1980年   55篇
  1979年   54篇
  1978年   40篇
  1977年   24篇
  1976年   23篇
  1973年   7篇
排序方式: 共有10000条查询结果,搜索用时 609 毫秒
101.
BACKGROUND: The aim of the present randomized study was to determine the effect of adding sufentanil to bupivacaine, compared with bupivacaine alone in caudal block, on the surgical stress response in children. METHODS: The children were premedicated with midazolam 0.5 mg/kg. All children received induction with nitrous oxide and sevoflurane. Anesthesia was maintained with the same volatile agents in the both groups. The children were randomly allocated to two groups. Group I received bupivacaine alone (n = 17) and group II received bupivacaine + sufentanil (n = 16). Caudal block was performed with 0.25% bupivacaine 2 mg/kg (group I) or 0.25% bupivacaine 2 mg/kg with sufentanil 0.5 microg/kg (group II) after induction of anesthesia. Blood samples were obtained after induction of anesthesia (T(0)) to measure baseline concentrations of cortisol, prolactin, glucose and insulin. Additional samples were obtained 30 min after the start of surgery (T(1)), and 60 min after the end of surgery (T(2)). RESULTS: All of the basal values (T(0)) were within the normal ranges of the authors' laboratory for children of this age group and there were no differences between the groups (P > 0.05). In both groups, glucose concentration increased at T(1), compared with T(0) and T(2) (P < 0.05). The glucose concentration was unchanged at T(2) compared with T(0) in both group (P > 0.05). In both groups, prolactin concentration increased at T(1), compared with T(0) and decreased at T(2), compared with T(1) (P < 0.05). Cortisol decreased at T(1) and T(2), compared with T(0) in both groups. (P < 0.05). Insulin concentration remained unchanged at T(0) and T(2), but increased slightly at T(1) in both groups (P > 0.05). There were no significant differences in plasma prolactin, cortisol, glucose and insulin levels between the two groups at T(1) and T(2) (P > 0.05). CONCLUSION: There is no advantage in adding 0.5 microg/kg sufentanil to bupivacaine over bupivacaine alone in the caudal block, with regard to the surgical stress response in children.  相似文献   
102.
Bone mineral density (BMD, g/cm2) was measured using dual-photon absorptiometry (DPA) in selected areas of the proximal tibia following uncemented PCA knee prosthesis. In nine patients with 14 alloplastic operations, measurements were taken at 3-6-month intervals for the first 3 1/2 years after operation. There was a significant increase in BMD of about 15% during the first 6 months after operation. The following year it remained increased, although not significantly, compared with the initial values, then gradually diminished. Increased bone density after arthroplasty may be explained mainly by stimulation of bone formation from weight bearing due to improved walking ability. Stress shielding of the proximal part of the supporting tibial bone did not seem to occur.  相似文献   
103.
Background The aim of the present study was to identify factors associated with the level of psychological distress reported by family carers of children with intellectual disability living in a large urban conurbation. Method Information was collected by postal questionnaire (or interview for family carers who did not have English as their first language) from the family carers of 408 children with intellectual disability (31% of all children within the area administratively identified as having an intellectual disability). Results Results indicated that 47% of primary carers scored above the threshold for psychological distress on the GHQ and that scoring above the threshold was strongly related to the emotional and behavioural needs of the index child and South‐Asian ethnicity and moderately associated with the severity of the child's delay in communication. Conclusions The rates of psychological distress (47% overall, 70% among South‐Asian carers) were markedly higher than that found in previous studies of carers supporting a child with intellectual disabilities. It is suggested that these elevated rates of psychological distress may be mediated by socio‐economic deprivation.  相似文献   
104.
Functional dyspepsia (FD) is associated with impaired gastric accommodation and autonomic dysregulation. The aim of this study was to investigate the effects of autonomic manipulation on distension-induced gastric accommodation in subjects with and without FD, using a newly developed gastric barostat paradigm. Twelve healthy subjects (HS) and 18 subjects with FD had four barostat examinations each: no intervention, intravenous atropine (1 mg), vagal stimulation (mental relaxation with deep breathing) and acute stress stimulation (serial subtraction task). Intrabag pressure increased from 1 to 15 mmHg in 5 min (ramp phase), and was maintained at 15 mmHg for 5 min (tonic phase). Volume responses were analysed using predefined parameters. There were no significant group differences in accommodation variables between HS and subjects with FD. The FD group could be subdivided into two distinct subgroups: subgroup 1 (n = 7, 38%) with low maximum volume and accommodation rate, and subgroup 2 with normal accommodation (n = 11). In subgroup 1, but not in subgroup 2 atropine increased maximum volume and accommodation rate substantially. Neither mental stress nor mental relaxation changed any of the accommodation variables. In a subgroup of subjects with FD, impairment of distension-induced gastric accommodation can be improved by cholinergic blockade, but not by acute physiological autonomic manipulation.  相似文献   
105.
目的 观察高糖作用下大鼠系膜细胞(MsC)肝细胞生长因子(HGF)受体c-Met的表达,并探讨其机制和意义。 方法 用RT-PCR和Western 印迹方法检测高糖作用大鼠MsC的不同时间点(0、12、24、48、96 h)c-Met的表达。分别用光辉霉素A(mithramycin A)和SU11274抑制转录因子Sp1的DNA结合活性和阻断c-Met。用电泳迁移率改变实验(EMSA)观察Sp1与c-Met基因启动子的结合活性。以荧光探剂二氯双氢荧光素二乙酸酯(DCFH-DA)捕获细胞内活性氧。 结果 大鼠MsC的c-Met表达在高糖作用12、24和48 h都明显上升,96 h开始下降。光辉霉素A呈浓度依赖性抑制高糖作用下大鼠MsC的c-Met表达上调。大鼠MsC内Sp1与c-Met基因启动子的结合活性在高糖作用下明显增强。HGF及c-Met显著抑制高糖诱导的大鼠MsC内活性氧的增多。 结论 高糖作用下大鼠MsC的c-Met表达增强,其机制可能是通过Sp1介导。HGF-c-Met信号通路激活能抑制高糖所致大鼠MsC内的氧化应激反应。  相似文献   
106.
Lipid peroxidation in the brain cortex, striatum, hippocampus, and hypothalamus of rats of the KLA and KHA lines which were distinguished by their strategies of adaptive behavior was investigated following emotional-painful stress. Significant long-term changes in lipid peroxidation were shown to occur in the brain. These had a phase character and depended on the behavioral characteristics of the animals. The investigated brain regions were characterized by different reactions of lipid peroxidation to the stress. The induced depressive-like states (on the 21st day after the stress) in rats of the KLA and KHA lines were distinguished by the largest changes in lipid peroxidation in the striatum and hypothalamus and in the striatum and hippocampus, respectively. One could conclude on the basis of these results that both identical and different mechanisms of formation and development of depression existed in the animals with different behavioral strategies.  相似文献   
107.
This paper describes a response directed stress management intervention (SMI) in the form of a Jungian based preference awareness education (PAE). It uses the Insights System of personality types to increase awareness of behaviour and communication preferences of self and different others. Eighteen self‐recruited academic employees participated for 7 weeks and received feedback about work preferences and personality type. The aim was to reduce perceptions of stress and interpersonal stress and to increase feelings of job satisfaction and interpersonal satisfaction. The data were analysed using two‐tailed t‐tests. No significant findings were observed for the total sample after training, however, interesting results were found for certain sub‐sample groups. Extravert‐thinking types, reported decreased stress levels (p > 0.018), and participants suffering high stress/interpersonal stress pre‐PAE, reported decreased stress levels (p > 0.010–0.018). Participants suffering low job/interpersonal satisfaction pre‐PAE, reported increased job satisfaction (p > 0.015–0.016). These results suggest that individuals who report high levels of stress and dissatisfaction are most likely to benefit from this type of intervention. Future PAE research might: (a) use pilot studies to meet the intervention preferences of employees that are reluctant to participate in SMIs; (b) include a wait‐list control group; use: (c) a follow up education/measures; (d) and organizational level (stressor directed) SMIs at the same time as response directed initiatives. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   
108.
Previous work suggests that secretory immunoglobulin‐A (S‐IgA) reactivity is inversely related to the perceived demands of the stressor. The Defined Intensity Stressor Simulation (DISS) comprises eight stressor modules, and allows for the manipulation of stress either through increasing the number of modules, or increasing the workload of the modules. The current study assessed the effect of increasing the workload of four modules upon S‐IgA reactivity and perceived demands. Participants (N = 14) attended three sessions on consecutive days where they provided a timed saliva sample immediately before and after 5 min on the DISS at low, medium and high workload. Following each session participants recorded their perceptions of the task with regard to workload and levels of stress and arousal. Perceived workload and stress, but not arousal, increased in accordance with increases in workload, however, differential S‐IgA reactivity was observed. Low workload resulted in a slight increase in S‐IgA secretion; medium workload elicited significant up‐regulation, while down‐regulation of S‐IgA occurred following high workload. As DISS is analogous to a variety of working environments it is suggested that the observed S‐IgA reactivity is indicative of how individuals react to multi‐tasking environments when faced with increases in objective or perceived workload demands. As S‐IgA levels are related to protection from illness, down‐regulation of S‐IgA in those who perceive greater demands may lead to greater vulnerability to ill‐health. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   
109.
110.
精神科护士的职业压力调查   总被引:5,自引:0,他引:5  
目的调查精神科护士在工作中面临的职业压力。方法采用问卷调查法,对贵州省贵阳市两所医院精神科61名护士与贵州省贵阳市多所医院173名护士的职业压力进行调查分析。结果精神科护士职业压力处于较高水平,其他科护士压力处于中等水平。结论建议从管理角度减轻精神科护士工作压力,并对精神科护士进行减轻工作压力的训练。  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