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   12790篇
  免费   1489篇
  国内免费   42篇
耳鼻咽喉   126篇
儿科学   398篇
妇产科学   256篇
基础医学   2126篇
口腔科学   268篇
临床医学   1588篇
内科学   2440篇
皮肤病学   254篇
神经病学   1037篇
特种医学   475篇
外科学   1648篇
综合类   337篇
一般理论   16篇
预防医学   1480篇
眼科学   144篇
药学   1042篇
中国医学   8篇
肿瘤学   678篇
  2022年   103篇
  2021年   214篇
  2020年   105篇
  2019年   192篇
  2018年   215篇
  2017年   162篇
  2016年   198篇
  2015年   217篇
  2014年   284篇
  2013年   426篇
  2012年   569篇
  2011年   601篇
  2010年   321篇
  2009年   324篇
  2008年   537篇
  2007年   551篇
  2006年   571篇
  2005年   536篇
  2004年   532篇
  2003年   481篇
  2002年   438篇
  2001年   402篇
  2000年   424篇
  1999年   363篇
  1998年   174篇
  1997年   148篇
  1996年   134篇
  1995年   122篇
  1994年   116篇
  1993年   121篇
  1992年   271篇
  1991年   288篇
  1990年   276篇
  1989年   282篇
  1988年   259篇
  1987年   235篇
  1986年   225篇
  1985年   214篇
  1984年   201篇
  1983年   159篇
  1982年   107篇
  1981年   120篇
  1980年   108篇
  1979年   172篇
  1978年   162篇
  1977年   136篇
  1976年   119篇
  1975年   104篇
  1974年   143篇
  1973年   128篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Aims: Effective communication enhances team building and is perceived to improve the quality of team performance. A recent publication from the Resuscitation Council (UK) has highlighted this fact and recommended that cardiac arrest team members make contact daily. We wished to identify how often members of this team communicate prior to a cardiopulmonary arrest. Method: A questionnaire on cardiac arrest team composition, leadership, communication and debriefing was distributed nationally to Resuscitation Training Officers (RTOs) and their responses analysed. Results: One hundred and thirty (55%) RTOs replied. Physicians and anaesthetists were the most prominent members of the team. The Medical Senior House Officer is usually nominated as the team leader. Eighty-seven centres (67%) have no communication between team members prior to attending a cardiopulmonary arrest. In 33%, communication occurs but is either informal or fortuitous. The RTOs felt that communication is important to enhance team dynamics and optimise task allocation. Only 7% achieve a formal debrief following a cardiac arrest. Conclusion: Communication between members of the cardiac arrest team before and after a cardiac arrest is poor. Training and development of these skills may improve performance and should be prioritised. Team leadership does not necessarily reflect experience or training.  相似文献   
993.
994.
995.
996.
Fractures of the calcaneus with associated locked dislocation of the posterior facet have been previously described. Two patients with a calcaneal fracture with a locked dislocation of a portion of the posterior facet were treated with minimally invasive open reduction and percutaneous screw fixation of the fragment with cannulated screws. Both patients had satisfactory reductions and healed the fractures without any soft-tissue complications. This technique can be a useful addition to the armamentarium of the surgeon treating these injuries, especially in the patient at high risk for wound complications.  相似文献   
997.
16Alpha-hydroxyestrone (16alpha-OHE(1)), an endogenous estrogen metabolite, is associated with increased bone density in postmenopausal women. This study was designed to evaluate the long-term activity of this metabolite on bone, uterus, and serum cholesterol in an animal model for postmenopausal bone loss. A preliminary dose-response study performed in weanling rats determined 2000 microg/kg/day to be the optimal dose of 16alpha-OHE(1) for studying estrogenic effect on bone. The long-term experiment was performed in 6-month-old animals that were either sham-operated or OVX. The OVX rats were implanted sc with 60-day continuous-release carrier, 17beta-estradiol (E(2)) (33 microg/kg/day) or 16alpha-OHE(1) pellets (2000 microg/kg/day). OVX decreased uterine weight, increased body weight, serum cholesterol, and all dynamic bone histomorphometric measurements in cortical and cancellous bone, and resulted in a 54% bone loss at the tibial metaphysis. E(2) completely prevented OVX-induced bone loss, suppressed bone turnover, and induced uterine hypertrophy and hypercholesterolemia. 16alpha-OHE(1) acted as an E(2) agonist on bone, suppressing bone formation and resorption. However, the estrogen metabolite lowered serum cholesterol and was only a partial E(2) agonist on uterine weight and epithelial cell height. These results suggest that 16alpha-OHE(1) is an estrogen agonist on bone and may be responsible, in part, for the cholesterol-lowering activity attributed to estrogen. As a consequence of its skeletal effects, older women who produce high levels of 16alpha-OHE(1) could have a lower risk for developing postmenopausal osteoporosis than women who produce less-active estrogen metabolites.  相似文献   
998.
The effects of marijuana on brain perfusion and internal timing were assessed using [15O] water PET in occasional and chronic users. Twelve volunteers who smoked marijuana recreationally about once weekly, and 12 volunteers who smoked daily for a number of years performed a self-paced counting task during PET imaging, before and after smoking marijuana and placebo cigarettes. Smoking marijuana increased rCBF in the ventral forebrain and cerebellar cortex in both groups, but resulted in significantly less frontal lobe activation in chronic users. Counting rate increased after smoking marijuana in both groups, as did a behavioral measure of self-paced tapping, and both increases correlated with rCBF in the cerebellum. Smoking marijuana appears to accelerate a cerebellar clock altering self-paced behaviors.  相似文献   
999.
The authors tested the hypotheses that neuropsychological functioning would improve after homeless persons with severe and persistent mental illness were provided with housing and that executive functioning would improve more among those placed in group homes than among those placed in independent apartments. A total of 114 persons with serious and persistent mental illness who were stable residents of homeless shelters completed neuropsychological testing and were randomly assigned to group homes or independent apartments; 91 participants (52 assigned to group homes and 39 assigned to independent apartments) were retested after 18 months. Overall neuropsychological functioning improved significantly across the full study sample. Executive performance, measured by the Wisconsin Card Sorting Test, decreased significantly among persons assigned to independent apartments and increased, but not significantly, among those assigned to group homes. The findings suggest that providing housing for persons who have severe and persistent mental illness improves cognitive functioning but that independent living may diminish executive functioning.  相似文献   
1000.
Clozapine is a potent atypical neuroleptic or antipsychotic agent used to relieve symptoms of early-diagnosed schizophrenia. Aside from well-described dopamine and serotonin receptor blockade effects, clozapine may also be neuroprotective through its modulation of the p75 neurotrophin receptor (p75(NTR)) and superoxide dismutase 1 (SOD1) expression. The death-signalling activities of both p75(NTR) and mutant SOD1 are implicated in motor neuron degeneration in humans and transgenic mice with amyotrophic lateral sclerosis (ALS). We therefore investigated the effects of clozapine in cell culture and mouse models of ALS. Clozapine dose-dependently inhibited full-length and cleaved p75(NTR) but not SOD1 protein expression in the motor neuron-like (NSC-34) cell line. Furthermore, low concentrations of clozapine protected NSC-34 cells from paraquat-mediated superoxide toxicity, nerve growth factor (NGF)-induced death signalling, and serum deprivation, whereas high concentrations potentiated death. Systemic thrice-weekly administration of low and high-dose clozapine to mutant superoxide dismutase 1 (SOD1(G93A)) mice produced differential effects on disease onset and survival. Low-dose treatment was associated with delayed locomotor impairment and death, compared to high-dose clozapine, which accelerated paralysis and mortality (P < 0.05). Increased death was not attributable to toxicity, as clozapine-induced agranulocytosis was not detected from blood analysis. High-dose clozapine, however, produced extrapyramidal symptoms in mice manifest by hindlimb rigidity, despite reducing spinal cord p75(NTR) levels overall. These results suggest that although clozapine may exert p75(NTR)-mediated neuroprotective activity in vitro, its profound antagonistic effects on dopaminergic and serotonergic systems in vivo at high doses may exacerbate the phenotype of transgenic ALS mice.  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