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   388篇
  免费   41篇
  国内免费   1篇
耳鼻咽喉   4篇
儿科学   20篇
妇产科学   14篇
基础医学   35篇
口腔科学   28篇
临床医学   45篇
内科学   58篇
皮肤病学   5篇
神经病学   49篇
特种医学   18篇
外科学   33篇
综合类   11篇
一般理论   1篇
预防医学   21篇
眼科学   8篇
药学   41篇
中国医学   3篇
肿瘤学   36篇
  2024年   1篇
  2023年   5篇
  2022年   16篇
  2021年   28篇
  2020年   8篇
  2019年   20篇
  2018年   30篇
  2017年   25篇
  2016年   18篇
  2015年   7篇
  2014年   23篇
  2013年   31篇
  2012年   31篇
  2011年   31篇
  2010年   20篇
  2009年   21篇
  2008年   23篇
  2007年   19篇
  2006年   14篇
  2005年   11篇
  2004年   5篇
  2003年   5篇
  2001年   1篇
  1999年   3篇
  1998年   3篇
  1997年   1篇
  1996年   3篇
  1993年   1篇
  1992年   1篇
  1991年   2篇
  1990年   4篇
  1989年   4篇
  1988年   1篇
  1985年   1篇
  1983年   1篇
  1982年   3篇
  1981年   1篇
  1980年   3篇
  1977年   1篇
  1974年   2篇
  1973年   2篇
排序方式: 共有430条查询结果,搜索用时 15 毫秒
101.
102.
ObjectivesThe purpose of this study was to investigate the distribution pattern of genes responsible for erythromycin and tetracycline resistance and their association with resistance phenotypes in enterococcus isolates.Materials and MethodsEighty-six Enterococcus faecalis and 26 E. faecium isolates were collected from 2 hospitals in Kerman, Iran. Minimum inhibitory concentration of erythromycin and tetra­cycline was determined and then genes encoding resistance to erythromycin − erm (A-C), mef, and msr − and tetracycline − tet (M), tet (O), tet (S), tet (K), and tet (L) − were investigated.ResultsIn all resistant isolates (n = 72, 64%), high-level resistance to both tested antibiotics was found. The most prevalent erm gene was erm (B) (77.7%), followed by erm (A) (15.2%) and erm (C) (8.3%). Genes mediating erythromycin efflux were detected in 70.8% (mef) and 9.7% (msr) of resistant isolates. Regarding tetracycline, tet (M) was detected at the highest rate (50%), followed by tet (O) (31%) and tet (S) (11%). Export of tetracycline was found in 31% (tet (K)) and 12% (tet (L)) of isolates.ConclusionA high prevalence of high-level resistance to both erythromycin and tetracycline was documented. Alterations at the ribosomal level was more frequently detected in erythromycin and tetracycline resistance than efflux systems. Concurrent resistance mechanisms were more involved in resistance to erythromycin than tetracycline.  相似文献   
103.
Common variable immunodeficiency (CVID) is a primary immunodeficiency disease characterized by hypogammaglobulinemia and recurrent bacterial infections. The records of 65 patients with CVID (37 males and 28 females) in the age range of 24 to 537 months were reviewed. By the year 2003, 11 patients had died and seven patients could not be located. The total follow-up period was 221 patient-years. The median diagnostic delay (time between onset and diagnosis) in our patient group was 60 months. At the time of diagnosis, the baseline serum immunoglobulin G (IgG), IgM, and IgA levels were below the level normal for the patients' age; the medians for this group were 120, 10, and 0 mg/dl, respectively. All of the patients presented with infectious diseases at the time of onset, the most common of which were otitis media, diarrhea, pneumonia, and sinusitis. Acute and recurrent infections were also found in almost all of the patients, particularly involving respiratory and gastrointestinal systems. The most common infections, before diagnosis and during follow-up, were pneumonia, acute diarrhea, acute sinusitis, and otitis media. CVID should be considered in any patient with a history of recurrent infections and decreased levels of all serum immunoglobulin isotypes.  相似文献   
104.
One of the mechanisms by which the experience-dependent reorganization of neural circuitry can occur is through changes in synaptic strength. Almost every excitatory synapse in the mammalian brain exhibits LTP (long-term potentiation) or LTD (long-term depression), two cellular mechanisms of synaptic plasticity. However, LTP and LTD have been reported much more rarely at fast inhibitory GABAA receptor synapses. Our recent study suggests that in vivo morphine initiates a long-lasting alteration of GABAergic synapses in the ventral tegmental area (VTA) by blocking the mechanisms required for LTP of GABAergic synapses. Here we put this work into the context of other examples of synaptic plasticity at GABAergic synapses.  相似文献   
105.
In this study, the effects of chronic morphine administration (20–30 days) on long-term potentiation (LTP) were investigated at the Schaffer collateral–CA1 pyramidal cell synapses of the rat hippocampal slices. Orthodromic population spike (OPS) amplitude and delay (peak latency) were measured as indices of increase in synaptic efficacy. The amounts of LTP of OPS delay and LTP of OPS amplitude were higher in slices from dependent rats. Perfusion of slices from control and dependent rats with morphine containing ACSF and delivering tetanic stimulation, showed that short-term presence of morphine could not mimic the LTP enhancing effects of chronic morphine administration, however, attenuated the amount of LTP of OPS amplitude in slices of dependent rats. This study supports the hypothesis that the susceptibility of CA1 synapses to plastic changes increases by chronic, not acute exposure to morphine and suggests that a withdrawal phenomenon might be an underlying mechanism for the observed augmented LTP of OPS amplitude in slices of dependent rats.  相似文献   
106.
107.
Objective: Breast cancer is a heterogeneous disease and very common malignancy in women worldwide. The efficacy of chemotherapy as an important part of breast cancer treatment is limited due to its side effects. While pharmaceutical companies are looking for better chemicals, research on traditional medicines that generally have fewer side effects is quite interesting. In this study, apoptosis and necrosis effect of Arctium lappa and doxorubicin was compared in MCF7, and MDA-MB-231 cell lines. Materials and Methods: MCF7 and MDA-MB-231 cells were cultured in RPMI 1640 containing 10% FBS and 100 U/ml penicillin/streptomycin. MTT assay and an annexin V/propidium iodide (AV/PI) kit were used respectively to compare the survival rate and apoptotic effects of different concentrations of doxorubicin and Arctium lappa root extract on MDA-MB-231 and MCF7 cells. Results: Arctium lappa root extract was able to reduce cell viability of the two cell lines in a dose and time dependent manner similar to doxorubicin. Flow cytometry results showed that similar to doxorubicin, Arctium Lappa root extract had a dose and time dependent apoptosis effect on both cell lines. 10μg/mL of Arctium lappa root extract and 5 μM of doxorubicin showed the highest anti-proliferative and apoptosis effect in MCF7 and MDA231 cells. Conclusion: The MCF7 (ER/PR-) and MDA-MB-231 (ER/PR+) cell lines represent two major breast cancer subtypes. The similar anti-proliferative and apoptotic effects of Arctium lappa root extract and doxorubicin (which is a conventional chemotherapy drug) on two different breast cancer cell lines strongly suggests its anticancer effects and further studies.  相似文献   
108.
Significant populations in burn centers are diabetic burn patients. Healing process in these patients is more difficult due to diabetes complications. The gold standard treatment for patients with grade 3 burn ulcer is split-thickness skin grafting (STSG), but in the diabetic patients, the rate of graft failure and amputation is high due to impaired tissue perfusion. The technique of low level laser therapy (LLLT) improves tissue perfusion and fibroblast proliferation, increases collagen synthesis, and accelerates wound healing. The purpose of this case report is introducing a new therapeutic method for accelerating healing with better prognosis in these patients. The protocols and informed consent were reviewed according to the Medical Ethics, Board of Shahid Beheshti Medical Sciences (IR.SBMU.RAM.REC.13940.363). Diabetic type 2 patients with 13 grade 3 burn ulcers, candidate for amputation, were enrolled in the study. We used a 650-nm red laser light, 2 J/Cm for the bed of the ulcer and an 810-nm infrared laser light 6 J/Cm2 for the margins along with intravenous laser therapy with a 660-nm red light, before and after STSG for treating grade 3 burn ulcers in 13 diabetic ulcers. The results of this study showed complete healing in the last 8 weeks for all patients who were candidates for amputation. In this case series, we present 13 cases of diabetic ulcer with type 3 burn wound, candidate for amputation, who healed completely using LLLT and STSG. This is the first time that these two techniques are combined for treatment of burn ulcer in diabetic patients. Using LLLT with STSG might be a promising treatment for burn victims especially diabetic patients.  相似文献   
109.

Aims

To estimate the prevalence and trends of diabetes mellitus (DM) and impaired fasting glucose (IFG), 2005–2011, and to determine the contribution of obesity to DM prevalence.

Patients and methods

Data from Surveillance of Risk Factors of Non-communicable Diseases (SuRFNCD) conducted in 2005, 2007, and 2011 were gathered. DM was defined as presence of self-reported previous diagnosis or a fasting plasma glucose (FPG) ≥ 7 mmol/L. IFG was diagnosed with FPG levels between 5.6 and 6.9 mmol/L. Prevalence rates for 2011 and trends for 2005–2011 were determined by extrapolating survey results to Iran's adult population. Population attributable fraction (PAF) of obesity was also calculated.

Results

In 2011, IFG and total DM prevalence rates were 14.60% (95%CI: 12.41–16.78) and 11.37% (95%CI: 9.86–12.89) among 25–70 years, respectively. DM was more common in older age (p < 0.0001), in women (p = 0.0216), and in urban-dwellers (p = 0.0001).In 2005–2011, trend analysis revealed a 35.1% increase in DM prevalence (OR: 1.04, 95%CI: 1.01–1.07, p = 0.011); albeit, IFG prevalence remained relatively unchanged (OR: 0.98, 95%CI: 0.95–1.00, p = 0.167). In this period, DM awareness improved; undiagnosed DM prevalence decreased from 45.7% to 24.7% (p < 0.001). PAF analysis demonstrated that 33.78%, 10.25%, and 30.56% of the prevalent DM can be attributed to overweight (BMI ≥ 25 kg/m2), general obesity (BMI ≥ 30 kg/m2), and central obesity (waist circumference ≥ 90 cm), respectively. Additionally, the DM increase rate in 2005–2011, was 20 times higher in morbidly obese compared with lean individuals.

Conclusion

More than four million Iranian adults have DM which has increased by 35% over the past seven years, owing in large part, to expanding obesity epidemic.  相似文献   
110.
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