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   1521篇
  免费   79篇
  国内免费   8篇
耳鼻咽喉   14篇
儿科学   63篇
妇产科学   77篇
基础医学   165篇
口腔科学   43篇
临床医学   101篇
内科学   264篇
皮肤病学   73篇
神经病学   65篇
特种医学   76篇
外国民族医学   1篇
外科学   247篇
综合类   30篇
一般理论   3篇
预防医学   115篇
眼科学   34篇
药学   111篇
中国医学   1篇
肿瘤学   125篇
  2023年   12篇
  2022年   47篇
  2021年   70篇
  2020年   54篇
  2019年   56篇
  2018年   86篇
  2017年   51篇
  2016年   65篇
  2015年   49篇
  2014年   95篇
  2013年   87篇
  2012年   117篇
  2011年   101篇
  2010年   65篇
  2009年   58篇
  2008年   59篇
  2007年   55篇
  2006年   44篇
  2005年   54篇
  2004年   41篇
  2003年   33篇
  2002年   30篇
  2001年   23篇
  2000年   12篇
  1999年   11篇
  1995年   5篇
  1994年   4篇
  1992年   5篇
  1991年   10篇
  1990年   7篇
  1989年   4篇
  1988年   11篇
  1987年   9篇
  1986年   15篇
  1985年   24篇
  1984年   10篇
  1983年   22篇
  1982年   4篇
  1981年   4篇
  1980年   4篇
  1979年   8篇
  1978年   5篇
  1977年   6篇
  1976年   7篇
  1975年   13篇
  1974年   5篇
  1973年   9篇
  1972年   8篇
  1971年   6篇
  1967年   4篇
排序方式: 共有1608条查询结果,搜索用时 15 毫秒
51.
Cyclophosphamide is an anticancer and immunosuppressive agent used in the treatment of various malignancies but causing gastrointestinal distress. Cannabis sativa and its derivatives have been used for the treatment of human gastrointestinal disorders. A purpose of this study was to investigate the effect of C. sativa on nausea induced by cyclophosphamide in rats. The rats were divided into four groups (eight animals per group): Group 1: Normal control (saline i.p.). Group 2: Rats received cyclophosphamide (200 mg/kg i.p.) 3 consecutive days. Group 3 and 4: Rats received cyclophosphamide (200 mg/kg i.p.) across Days 1–7, and C. sativa (20 and 40 mg/kg s.c.) was administered on cyclophosphamide days 4–7. We examined intake of kaolin, normal food and changes in body weight, as an indicator of the emetic stimulus. Oxidative stress markers, antioxidant enzymes status, serotonin (5-HT), dopamine, noradrenaline and CB1R levels were evaluated in the intestinal homogenate. Moreover, histopathological study was performed. Results showed that C. sativa ameliorates cyclophosphamide-induced emesis by increasing in body weight and normal diet intake with a decrease in kaolin diet intake after 7 days. Moreover, C. sativa significantly decreases (serotonin) 5-HT, dopamine and noradrenaline, as well as decreasing oxidative stress and inflammation. Administration of C. sativa significantly increased the expression of CB1R in intestinal homogenate. Treatment with C. sativa also improved the histological feature of an intestinal tissue. These results suggested that C. sativa possess antiemetic, antioxidant and anti-inflammatory effects in chemotherapy-induced nausea in rats by activating CB1R.  相似文献   
52.
Adenosine monophosphate kinase/liver kinase B1/peroxisome proliferator-activated receptor-γ coactivator 1-α (AMPK/LKB1/PGC1α) pathway has a vital role in regulating age-related diseases. It controls neurogenesis, cell proliferation, axon outgrowth, and cellular energy homeostasis. AMPK pathway also regulates mitochondrial synthesis. The current study evaluated the effect of chrysin on D-galactose (D-gal) induced-aging, neuron degeneration, mitochondrial dysfunction, oxidative stress, and neuroinflammation in mice. The mice were allocated randomly into four groups (10 each group): Group 1: normal control group, Group 2: D-gal group, Groups 3 and 4: chrysin (125 and 250 mg/kg, respectively). Groups 2–4 were injected with D-gal (200 mg/kg/day; s.c) for 8 weeks to induce aging. Groups 3 and 4 were orally gavaged every day concurrent with D-gal. At the end of experiment, behavioral, brain biochemical and histopathological changes were monitored. Chrysin administration elevated discrimination ratio in object recognition, Y Maze percentage alternation, locomotor activity and brain contents of AMPK, LKB1, PGC1α, NAD (P)H quinone oxidoreductase 1 (NQO1), heme oxygenase 1 (HO-1), nerve growth factor (NGF) (neurotrophin-3; NT-3), and seretonin as well as reduced brain contents of tumor necrosis factor-alpha (TNF-α), nuclear factor kappa B (NF-κB), advanced glycation end products (AGEs) and glial fibrillary acidic protein (GFAP) compared to D-gal-treated mice. Chrysin also alleviated cerebral cortex and white matter neurons degeneration. Chrysin protects against neurodegeneration, improves mitochondrial autophagy and biogenesis as well as activates antioxidant genes expression. In addition, chrysin ameliorates neuroinflammation and stimulates the release of NGF and serotonin neurotransmitter. So, chrysin has a neuroprotective effect in D-gal induced-aging in mice.  相似文献   
53.
We aimed to determine the ability of partial nephrectomy to prevent end‐stage renal disease and tumor recurrence or progression in patients with upper tract urothelial carcinoma. Retrospectively, eight patients undergoing partial nephrectomy for upper tract urothelial carcinoma were identified and their medical records reviewed. All patients had imperative indications for nephron sparing, and diagnosis of upper tract urothelial carcinoma not adequately amenable to endoscopic management. Although three patients suffered acute tubular necrosis, only one required postoperative hemodialysis. During the follow‐up period 25% (2/8) developed end‐stage renal disease, including the one patient who had received postoperative hemodialysis. Recurrences occurred in five of seven patients with adequate oncological surveillance. Recurrences were successfully treated endoscopically in 80% (4/5) patients, and one patient had metastases. Of the eight patients, four have died. Death occurred 4 months, 1 year, 1.2 years and 3.5 years after partial nephrectomy. Of these patients, one succumbed to metastatic disease; the exact cause of death is unknown in the other three, but there was no documentation of metastatic cancer. The mean duration of follow up in the remaining four patients, all without evidence of metastatic urothelial cancer, is 71 months (range 22–108 months). In summary, partial nephrectomy for upper tract urothelial carcinoma in patients with imperative indications averts end‐stage renal disease in most patients, and appears to be associated with acceptable disease‐specific survival. Partial nephrectomy is a sparingly used option in patients with upper tract urothelial carcinoma refractory to endoscopic management who have imperative indications for nephron sparing.  相似文献   
54.
55.
56.
Purpose:To compare visual outcomes and vision-related quality of life (VRQoL) between subjects before and after photorefractive keratotomy (PRK) and controls. In addition, VRQoL was compared between subjects at different periods of PRK surgery.Methods:This was a cross-sectional study that included subjects with refractive errors aged 19–40 years and age-matched controls. Subjects were divided into three groups: pre-, post-PRK, and control. Subjects in the post-PRK group were divided into three subgroups (1-week, <6-month, and >6-month follow-up visits). Measurements including uncorrected distance visual acuity (UCVA), corrected distance visual acuity (CDVA), spherical equivalent (SE) of manifest refraction, and corneal topography were obtained for all participants. The Quality of Life Impact of Refractive Correction (QIRC) questionnaire was administered to compare VRQOL between groups and between post-refractive surgery subgroups.Results:A total of 145 participants were included in this study. The mean age ± standard deviation (SD) of all participants was 26.29 ± 5.1 years. There was a significant difference (P < 0.001) in total QIRC scores between groups. The total QIRC score was better in the post-PRK group than in the pre-PRK and control groups. The scores of items included in the convenience, well-being, and health concern domains were significantly higher in the post-PRK group than in the pre-PRK and control groups. Within the post-PRK group, significant differences (P < 0.001) were found in UCVA and SE between the post-PRK subgroups. Uncorrected VA and SE were better in the post-PRK groups who were followed up in the < 6 and > 6 months subgroups than in the 1-week follow-up subgroup (P < 0.0001).Conclusion:A significant improvement in visual outcomes and VRQoL occurred after PRK surgery. Subjects enjoyed their VRQoL after refractive surgery.  相似文献   
57.
This study was conducted to explore the potential cardioprotective and anti-depressive effects of dichloromethane (DCM) fractions of Morus macroura leaves (L) and stem branches (S) on post-myocardial infarction (MI) depression induced by isoprenaline (ISO) in rats in relation to their metabolites. The study was propped with a UPLC-ESI-MS/MS profiling and chromatographic isolation of the secondary metabolites. Column chromatography revealed the isolation of lupeol palmitate (6) that was isolated for the first time from nature with eight known compounds. In addition, more than forty metabolites belonging, mainly to flavonoids, and anthocyanins groups were identified. The rats were injected with ISO (85 mg kg−1, s.c) in the first two days, followed by the administration of M. macroura DCM-L and DCM-S fractions (200 mg kg−1 p.o) for 19 days. Compared with the ISO exposed rats, the treated rats displayed a reduction in cardiac biomarkers (LDH and CKMB), anxiety, and depressive-like behaviour associated with an increase in the brain defense system (SOD and GSH), neuronal cell energy, GABA, serotonin, and dopamine, confirmed by histopathological investigations. In conclusion, DCM-L and DCM-S fractions'' cardioprotective and anti-depressive activities are attributed to their metabolite profile. Therefore, they could serve as a potential agent in amending post-MI depression.

This study was conducted to explore the potential cardioprotective and anti-depressive effects of dichloromethane fractions of Morus macroura leaves and stem branches on post-myocardial infarction depression induced by isoprenaline in rats in relation to their metabolites.  相似文献   
58.
The main objective of this study was to identify molecular mechanisms through which angiopoietin-1 (Ang-1), a ligand for Tie-2 receptors, influences endothelial cell apoptosis. Human umbilical vein endothelial cells were cultured in a medium enriched with 2% fetal bovine serum (FBS) and growth supplements. Apoptosis was induced over 24 h by reducing FBS to 0.1%. Activation of caspase-9, -8, -7, and -3 and the expression of Bcl-2 family proteins, inhibitors of apoptosis (IAPs), cytochrome c, as well as Smac proteins were evaluated with immunoblotting. Ang-1 clearly attenuated serum deprivation-evoked apoptosis, an effect which required Tie-2 receptor activation. Activation of caspase-9, -7, and -3, but not caspase-8, was inhibited by Ang-1. The inhibitory effects of Ang-1 on apoptosis and caspase activation were reversed by a PI-3 kinase inhibitor (wortmannin). Ang-1 exposure upregulated the expression of Survivin but not XIAP (members of IAPs), reduced the cystosolic levels of Smac, but not that of cytochrome c, and had no effect on the expression of Bcl-2 family proteins. This is the first study to report on the mitochondrial mechanisms through which Ang-1 inhibits apoptosis and to investigate the role of the newly discovered Smac. We conclude that Ang-1 inhibits endothelial cell apoptosis through several pathways, which include PI-3 kinase/AKT activation, inhibition of Smac release from the mitochondria, and upregulation of Survivin protein.  相似文献   
59.
60.
Nanocapsules can be equated to other nanovesicular systems in which a drug is entrapped in a void containing liquid core surrounded by a coat. The objective of the present study was to investigate the potential of polymeric and lipid nanocapsules (LNCs) as innovative carrier systems for miconazole nitrate (MN) topical delivery. Polymeric nanocapsules and LNCs were prepared using emulsification/nanoprecipitation technique where the effect of poly(ε-caprolactone (PCL) and lipid matrix concentrations with respect to MN were assessed. The resulted nanocapsules were examined for their average particle size, zeta potential, %EE, and in vitro drug release. Optimum formulation in both polymeric and lipidic nanocapsules was further subjected to anti-fungal activity and ex vivo permeation tests. Based on the previous results, nanoencapsulation strategy into polymeric and LNCs created formulations of MN with slow biphasic release, high %EE, and improved stability, representing a good approach for the delivery of MN. PNCs were best fitted to Higuchi’s diffusion while LNCs followed Baker and Lonsdale model in release kinetics. The encapsulated MN either in PNCs or LNCs showed higher cell viability in WISH amniotic cells in comparison with free MN. PNCs showed less ex vivo permeation. PNCs were accompanied by high stability and more amount drug deposition (32.2 ± 3.52 µg/cm2) than LNCs (12.7 ± 1.52 µg/cm2). The antifungal activity of the PNCs was high 19.07 mm compared to 11.4 mm for LNCs. In conclusion, PNCs may have an advantage over LNCs by offering dual action for both superficial and deep fungal infections.  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