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   1387篇
  免费   96篇
  国内免费   11篇
耳鼻咽喉   14篇
儿科学   53篇
妇产科学   51篇
基础医学   154篇
口腔科学   34篇
临床医学   112篇
内科学   306篇
皮肤病学   15篇
神经病学   85篇
特种医学   65篇
外科学   209篇
综合类   78篇
一般理论   2篇
预防医学   125篇
眼科学   36篇
药学   78篇
中国医学   10篇
肿瘤学   67篇
  2023年   9篇
  2022年   58篇
  2021年   68篇
  2020年   47篇
  2019年   47篇
  2018年   61篇
  2017年   42篇
  2016年   43篇
  2015年   62篇
  2014年   65篇
  2013年   96篇
  2012年   99篇
  2011年   110篇
  2010年   58篇
  2009年   49篇
  2008年   75篇
  2007年   79篇
  2006年   81篇
  2005年   57篇
  2004年   58篇
  2003年   45篇
  2002年   40篇
  2001年   11篇
  2000年   26篇
  1999年   9篇
  1998年   4篇
  1997年   3篇
  1995年   4篇
  1994年   5篇
  1993年   3篇
  1992年   3篇
  1991年   3篇
  1990年   9篇
  1989年   4篇
  1988年   4篇
  1987年   5篇
  1986年   2篇
  1985年   3篇
  1984年   2篇
  1983年   5篇
  1982年   2篇
  1979年   2篇
  1977年   2篇
  1976年   2篇
  1975年   2篇
  1973年   3篇
  1972年   3篇
  1968年   6篇
  1967年   3篇
  1965年   5篇
排序方式: 共有1494条查询结果,搜索用时 15 毫秒
1.
2.
3.
In obstructive jaundice, free radical production is increased and antioxidative activity is reduced. N-Acetylcysteine (NAC) has a beneficial effect with anti-inflammatory and antioxidant activity, acting as a free radical scavenger. NAC inhibits inducible nitric oxide synthase, suppresses cytokine expression/release, and inhibits adhesion molecule expression and nuclear factor kappa B. The aim of this study was to investigate the effects of NAC on liver/renal tissue and serum lipid peroxidation in lipopolysaccharide (LPS)-induced obstructive jaundice. We randomized 60 rats into 6 groups: group 1, Sham; group 2, obstructive jaundice (OJ) induced after bile-duct ligation; group 3, OJ + NAC (100 mg kg- 1 subcutaneously); group 4, OJ + LPS (10 mg kg-1); group 5, OJ + NAC + LPS; and group 6, OJ + LPS + NAC. For each group, the biochemical markers of lipid peroxidation and the antioxidant products were measured in serum and liver/renal tissue after sacrifice. Almost all lipid peroxidation products levels were increased and antioxidant products levels were decreased in groups who received LPS (groups 4, 5, and 6), but the effect was less remarkable when NAC was administered before LPS (group 5). The same trend was seen for groups with OJ +/- LPS who did not received NAC or received it after induced toxemia (groups 2, 4, and 6) as compared to groups 1 and 3. Moreover, in the case of OJ + LPS, rats treated with NAC before LPS (group 5) had lower lipid peroxidation products levels and higher antioxidant products levels as compared to those who did not received NAC (group 4). This phenomenon was not reproducible with NAC administered after LPS (group 6). Thus, results of this study showed that NAC prevents the deleterious effects of LPS in obstructive jaundice by reducing lipid peroxidation in serum and liver/renal tissue if administered before LPS. Nonetheless, NAC failed to prevent the lipid peroxidation in the case of established endotoxemia in obstructive jaundice.  相似文献   
4.
We have investigated whether the phenotype of myogenic clones derived from satellite cells of different muscles from the transgenic immortomouse depended on muscle type origin. Clones derived from neonatal, or 6- to 12-week-old fast and slow muscles, were analyzed for myosin and enolase isoforms as phenotypic markers. All clones derived from slow-oxidative muscles differentiated into myotubes with a preferentially slow contractile phenotype, whereas some clones derived from rapid-glycolytic or neonatal muscles expressed both fast and slow myosin isoforms. Thus, muscle origin appears to bias myosin isoform expression in myotubes. The neonatal clone (WTt) was cultivated in various medium and substrate conditions, allowing us to determine optimized conditions for their differentiation. Matrigel allowed expressions of adult myosin isoforms, and an isozymic switch from embryonic alpha- toward muscle-specific beta-enolase, never previously observed in vitro. These cells will be a useful model for in vitro studies of muscle fiber maturation and plasticity.  相似文献   
5.
2-benzoyl-3-phenylquinoxaline 1,4-dioxide (BPQ) and other substituted quinoxaline 1,4-dioxides (QdO) were tested for their ability to inhibit the stimulations of ornithine decarboxylase (ODC) enzyme activity and DNA synthesis, two biochemical markers linked to skin tumour promotion by ultraviolet B (UVB) radiation. Topical application of BPQ on the dorsal skin of hairless mice was found to inhibit in a dose-dependent manner UVB-induced ODC activity and DNA synthesis. When applied 20 min before UVB radiation, a dose of 17 mg BPQ applied in 0.4 ml of vehicle inhibited UVB-induced ODC activity and DNA synthesis by 95% and 85%, respectively. This inhibitory effect is dependent on the time of administration of BPQ relative to UVB radiation, with a generally greater inhibition observed when this compound is applied before rather than after UVB treatment. The inhibitory abilities of the other QdO on the ODC and DNA responses induced by UVB radiation greatly varied and appear to be dependent on the structure of the compounds and their metabolic activation in the skin following irradiation. The remarkable effectiveness of BPQ against the ODC and DNA markers of UVB promotion is also observed following multiple applications of this agent. These results suggest that QdO, in particular BPQ and certain derivatives of it, may be useful in protecting the skin against UVB-induced skin damage.  相似文献   
6.
338 women with age ranging from 15 to 69 years in a suburban Sudanese community were randomly selected and studied. Urine sample, high vaginal swabs and blood samples were investigated for bacterial vaginosis, candidiasis, trichomoniasis, gonorrhoea, HIV and syphilis. The sensitivity and specificity of some laboratory tests were evaluated. Bacterial vaginosis was found in 17.2% of the subjects, candidiasis in 10.1%, trichomoniasis in 7.7%, gonorrhoea in 1.2%, HIV in 1.2% and syphilis in 0.9% of the subjects. The sensitivity and specificity of amine test as a criterion for diagnosing bacterial vaginosis was 58.6% and 73.2%, respectively. The respective values of clue cells in wet preparation were 43.1% and 99.6%. The vaginal discharge in women with bacterial vaginosis lacked pus cells unless associated with concurrent infection.  相似文献   
7.
AIM: To evaluate the effect of prophylactic administration of nepafenac in prevention of macular edema occurring in diabetic patients after phacoemulsification and to investigate the correlation between optical coherence tomography (OCT) foveal thickness and multifocal electroretinogram (MF-ERG) parameters. METHODS: The study included two groups. Group 1 included 50 diabetic patients with senile cataract (50 eyes, 30 females, 20 males, aged 55±7y) received nepafenac 0.1% eye drop. Group 2 included another 50 diabetic patients with senile cataract (50 eyes, 22 female, 28 males, aged 53.8±8y) did not receive nepafenac. All patients were followed up for 3mo postoperatively. OCT and MF-ERG were done preoperative and at 1wk, 1, 2 and 3mo. RESULTS: The mean foveal thickness was statistically significantly lower in Group 1. Five eyes in Group 2 developed clinical cystoid macular oedema (CMO) (10%), and no patients in Group 1 developed central macular thickening more than 50 μm. There were insignificant differences in MF-ERG amplitudes and latencies between the two groups except in the five eyes that developed CMO, there statistically significant reduction of MF-ERG amplitude with increase in foveal thickness. CONCLUSION: Perioperative nepafenac reduces the incidence of CMO following uncomplicated phacoemulsification significantly. Nepafenac has no side effects.  相似文献   
8.
We present the case of an 18-year-old girl with a scoliosis (long C-shaped curve) in association with an atypical Rett’s syndrome. In order to attain a full correction and to provide her with adequate posture and sitting balance, segmental instrumentation was utilised from the high thoracic spine to the pelvis. We describe the procedure including the relevant pre-operative, intra-operative and post-operative imaging.  相似文献   
9.
Early recognition of neonatal hyperbilirubinemia is essential for prevention of bilirubin neurotoxicity and its long-term sequelae. High rates of home delivery in low- and middle-income countries (LMICs) as well as early discharge post-delivery (within 24hours) make community surveillance for neonatal hyperbilirubinemia highly important. Here, we performed a literature review to estimate the level of societal awareness of neonatal hyperbilirubinemia. We searched several databases for studies assessing the knowledge and awareness of neonatal hyperbilirubinemia. We retrieved 211 citations from 206 databases with five being in the grey literature. 52 selected articles were further reviewed. Data from these studies were then analyzed using Stata software (Statacorp® LLC Texas USA). We found that the pooled estimate of societal awareness of neonatal hyperbilirubinemia was 67% (95% confidence interval [CI]: 60, 74). There however was a publication bias (Begg test: P ≤ 0.01; Egger P = 0.06). Studies that scored or graded knowledge reported lower estimates [adjusted odds ratio (aOR) = -0.17; 95% CI: -0.32–0.02; P = 0.03]. Hospital location was an important determinant of awareness of complications [aOR = 0.30; 95% CI: 0.30–0.57; P = 0.03]. We therefore concluded that there is a significant need to improve societal awareness of neonatal hyperbilirubinemia.  相似文献   
10.
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