全文获取类型
收费全文 | 12675篇 |
免费 | 623篇 |
国内免费 | 112篇 |
专业分类
耳鼻咽喉 | 313篇 |
儿科学 | 631篇 |
妇产科学 | 531篇 |
基础医学 | 918篇 |
口腔科学 | 418篇 |
临床医学 | 1014篇 |
内科学 | 3241篇 |
皮肤病学 | 192篇 |
神经病学 | 748篇 |
特种医学 | 542篇 |
外科学 | 3022篇 |
综合类 | 171篇 |
一般理论 | 1篇 |
预防医学 | 291篇 |
眼科学 | 449篇 |
药学 | 453篇 |
中国医学 | 23篇 |
肿瘤学 | 452篇 |
出版年
2024年 | 11篇 |
2023年 | 110篇 |
2022年 | 208篇 |
2021年 | 388篇 |
2020年 | 245篇 |
2019年 | 304篇 |
2018年 | 380篇 |
2017年 | 307篇 |
2016年 | 523篇 |
2015年 | 598篇 |
2014年 | 652篇 |
2013年 | 785篇 |
2012年 | 1027篇 |
2011年 | 928篇 |
2010年 | 570篇 |
2009年 | 487篇 |
2008年 | 843篇 |
2007年 | 992篇 |
2006年 | 906篇 |
2005年 | 889篇 |
2004年 | 785篇 |
2003年 | 587篇 |
2002年 | 527篇 |
2001年 | 64篇 |
2000年 | 32篇 |
1999年 | 48篇 |
1998年 | 56篇 |
1997年 | 40篇 |
1996年 | 27篇 |
1995年 | 24篇 |
1994年 | 15篇 |
1993年 | 7篇 |
1992年 | 8篇 |
1991年 | 10篇 |
1990年 | 9篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1973年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Kahraman
ztürk Mehmet Baydar Yakup Alpay Aye encan Osman Orman Serkan Aykut 《Acta orthopaedica et traumatologica turcica》2022,56(2):105
Objective:This study aimed to evaluate clinical results, femoral head survival, and the need for total hip arthroplasty (THA) in patients with precollapse osteonecrosis of the femoral head (OFH) (Steinberg stage II and III) treated by free vascularized fibula graft (FVFG) application.Methods:We retrospectively reviewed 54 hips of 47 patients (39 males, eight females; mean age 36 ± 14 years) who underwent FVFG due to OFH, with at least two years of follow-up. The patient data, including Harris Hip Score (HHS), Visual Analogue Scale (VAS), and conversion to THA, were documented.Results:The right hip of 26 patients and the left hip of 28 patients were involved. Bilateral FVFG surgery was performed on seven patients due to bilateral OFH. The mean follow-up time was 5.5 (range 2-14) years. Survival of the femoral head was observed in 39 hips (72.2%), while the femoral head collapse was observed in 15 femoral heads (27.8%). The mean preoperative HHS increased from 46.5 (range = 12-85) to 86.5 (range = 33-100) postoperatively (P < 0.001). The mean preoperative VAS score improved from 8.2 (range = 2-10) to 1.3 (range = 0-10) postoperatively (P < 0.001). THA was performed on seven hips at a mean follow-up time of 1.8 years (range = 0.7–3.3). There was no significant difference in the collapse rate between unilateral or bilateral OFH (P = 0.175). A higher survival rate was observed in the Steinberg stage II femoral head patients compared to the stage III femoral head (P = 0.021).Conclusion:This study has shown that FVFG surgery can be a good option for managing patients with Steinberg stage II and III precollapse OFH to prevent femoral head collapse and joint function. 相似文献
72.
Lana Khalil Xingyu Gao Jeffrey M Switchenko Olatunji B Alese Mehmet Akce Christina Wu Maria Diab Bassel F El-Rayes Walid L Shaib 《The oncologist》2022,27(9):740
BackgroundThe survival impact of multi-agent (MAC) compared with single-agent (SAC) adjuvant chemotherapy (AC) in elderly patients with stage III colon cancer (CC) remains controversial. The aim of this study was to compare survival outcomes of MAC and SAC in this population utilizing the National Cancer Database (NCDB).Patients and MethodsPatients aged ≥70 years with pathological stage III CC diagnosed in 2004-2015 were identified in the NCDB. Univariate and multivariable analyses were conducted, and Kaplan-Meier analysis and Cox proportional hazard models were used to identify associations between MAC vs. SAC and overall survival (OS).ResultsAmong 41 707 elderly patients (≥70 years old) with stage III CC, about half (n = 20 257; 48.5%) received AC; the majority (n = 12 923, 63.8%) received MAC. The median age was 79 (range 70-90). The majority were female (n = 11 201, 55.3%), Caucasians (88%) and had moderately differentiated tumor grade (n = 12 619, 62.3%), tumor size >4 cm (11 785, 58.2%), and negative surgical margins (18 496, 91.3%). Low-risk stage III CC constituted 50.6% (n = 10 264) of the study population. High-risk stage III CC was associated with worse OS compared with low-risk disease (HR 0.35, 0.34-0.36, P < .001). Multi-agent chemotherapy was associated with a better 5-year OS compared with SAC (P < .001). High-risk stage III patients who received MAC vs. SAC had an OS of 4.2 vs. 3.4 years, respectively (P < .001). Low-risk stage III patients who received MAC vs. SAC had a median OS of 8.5 vs. 7 years (P < .001). In univariate and multivariable analyses, male sex, positive surgical margin, insurance and facility types, age, year of diagnosis, tumor size, and Charlson-Deyo score of >2 were associated with worse OS (P < .05).ConclusionsAny adjuvant chemotherapy has a trend of survival benefits. Multi-agent chemotherapy seems to have an enhanced benefit in the 70-75 age group. Multi-agent chemotherapy seemed to have similar efficacy as SAC in those aged >76 years. 相似文献
73.
ObjectiveTo determine the incidence of tuberculous lymphadenitis (TBL) and other pathologies in cervical lymphadenopathies in Somalia and accompanying radiological findings.MethodsIn this hospital‐based retrospective study, the demographic characteristics, pathology results and radiological findings of 263 patients who underwent ultrasound (US)‐guided cervical lymph node biopsy between January 2016 and February 2020 were analyzed.ResultsOf 241 patients 118 men and 123 women (mean age 27.9 ± 18.1 years) included in the study, 46.1% (n = 111) were diagnosed as necrotizing granulomatous lymphadenitis (caseified, consistent with TBL) and 21.6% (n = 12, atypical lymphoid cells and n = 40, metastases) as malignancy. The most common type of metastasis was squamous cell cancer (n = 31), and the primary source of most of them was esophageal cancer (16/31, 51.6%). The age of patients with TBL was significantly lower than that of non‐TBL (21.9 ± 14.6 vs. 41.9 ± 24.6, P = 0.003) and the incidence of TBL in pediatric patients was statistically higher (58.0% vs. 21.5%, P = 0.019). The rate of patients with TBL being localized at level 4 and level 5 was significantly more than non‐TBL patients (18.0% vs. 10.0% and 23.4% vs. 10.8%, respectively, P = 0.01). Half of patients with TBL who have chest radiography had pathological findings; consolidation and bronchopneumonia were present in 52.6% of them. There were 2 patients with paravertebral abscess and one patient with gastrointestinal tuberculosis.ConclusionIn Somalia, in the presence of cervical lymphadenopathy, after diagnosis by using US‐guided biopsy; primarily considering of TBL and malignancy, thoracic involvement should be investigated, and esophageal carcinoma must be excluded in terms of metastatic lymph node. 相似文献
74.
Ayse Gunes-Bayir Eray Metin Guler Mehmet Gultekin Bilgin Ilyas Samet Ergun Abdurrahim Kocyigit Agnes Dadak 《Nutrients》2022,14(14)
Carvacrol is a dietary polyphenol from Lamiaceae plants that has been shown to possess a wide range of biological activities including antioxidant and antitumor effects. This study aimed to investigate its anti-inflammatory and antioxidant effects on N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) induced gastric carcinogenesis in Wistar rats. Forty-nine rats were randomly assigned to four treatment and three control groups. Over 60 days, MNNG (200 mg/kg BW) was orally applied to animals of groups 1–5 while the rats in groups 2–5 also received different doses of carvacrol (10, 25, 50, and 100 mg/kg BW, respectively) until the end of the experiment. Group 6 rats were treated with 100 mg/kg BW carvacrol and no MNNG whereas group 7 was the control group without any treatment. After the euthanasia of all rats, the inflammatory cytokines and oxidative stress parameters were assessed in the blood and tissues. The expression of caspase 9, Bax, and Bcl-2 proteins in the stomach tissues were investigated through histopathological examinations. Statistically significant differences were observed in the body weight, oxidative stress, and inflammation parameters of groups 1 to 6 compared to group 7 (p ≤ 0.001). Animals in MNNG groups 2 and 3 treated with the low dose carvacrol (10 and 25 mg/kg BW) showed significantly reduced oxidative stress, inflammation, and apoptotic effect compared to animals of the MNNG groups receiving increased doses of carvacrol (50 and 100 mg/kg BW) or no carvacrol. Rats exposed to MNNG exhibited gastric cancer cells in several areas. In the MNNG group receiving 100 mg/kg BW carvacrol, the inflammatory cell infiltration was observed in gastric mucosal and submucosal areas whereas MNNG rats supplemented with 10 and 25 mg/kg BW carvacrol showed no pathological alterations of the gastric cells. The results of this study indicate that significant antioxidant and anti-inflammatory effects induced by carvacrol at doses of 10 and 25 mg/kg BW interfered with gastric carcinogenesis induced by MNNG in Wistar rats as well as provide hepatoprotection. However, high doses of carvacrol (50 and 100 mg/kg BW) increased oxidative stress, inflammation, and apoptosis. 相似文献
75.
Mehmet Unlu Emel Ergene Gulhan Vardar Unlu Hulya Sivas Zeytinoglu Nilufer Vural 《Food and chemical toxicology》2010
The essential oil from the bark of Cinnamomum zeylanicum Blume was analyzed by GC–MS and bioassays were carried out. Nine constituents representing 99.24% of the oil were identified by GC–MS. The major compounds in the oil were (E)-cinnamaldehyde (68.95%), benzaldehyde (9.94%) and (E)-cinnamyl acetate (7.44%). The antimicrobial activity of the oil was investigated in order to evaluate its efficacy against 21 bacteria and 4 Candida species, using disc diffusion and minimum inhibitory concentration methods. The essential oil showed strong antimicrobial activity against all microorganisms tested. The cytotoxic and apoptotic effects of the essential oil on ras active (5RP7) and normal (F2408) fibroblasts were examined by MTT assay and acridine orange/ethidium bromide staining, respectively. The cytotoxicity of the oil was quite strong with IC50 values less than 20 μg/mL for both cell lines. 5RP7 cells were affected stronger than normal cells. Morphological observation of apoptotic cells indicated the induction of apoptosis at the high level of the oil, especially in 5RP7 cells. The present study showed the potential antimicrobial and anticarcinogenic properties of the essential oil of cinnamon bark, indicating the possibilities of its potential use in the formula of natural remedies for the topical treatment of infections and neoplasms. 相似文献
76.
Budancamanak M Kanter M Demirel A Ocakci A Uysal H Karakaya C 《Archives of toxicology》2006,80(11):768-776
The goal of this investigation was to study the protective effects of thymoquinone (TQ) and methotrexate (MTX) on collagen-induced arthritis (CIA) in rats. On day 0 under ether anesthesia, the experimental groups were immunized with 0.5 mg native chick collagen II (CII) solubilized in 0.1 M acetic acid and emulsified in Freund's incomplete adjuvant. Control rats were gavaged with vehicle, whereas CII was administered intradermally. In addition, arthritis treated with TQ group received TQ (10 mg kg(-1) bw by gavage once a week for 3 weeks starting on day 0); and arthritis treated with MTX group received MTX (MTX was suspended in corn oil and administered by gavage at 1 mg kg (-1) bw once a week for 3 weeks starting on day 0). A significant decrease in the incidence and severity of arthritis by clinical and radiographic assessments was found in recipients of therapy, compared with that of controls. The MTX treatment significantly (P<0.01) decreased the elevated serum NO, urea and creatinine in arthritic rats. Likewise, TQ treatment was also able to reduce significantly (P<0.05) serum NO, urea and creatinine levels, but to lesser extent than MTX. The histopathologic abnormalities are consistent with the hydropic epithelial cell degenerations and moderate tubular dilatation in the some proximal and distal tubules. The severity of the degenerative changes in most of the shrunken glomerules and vascular congestion were also observed in arthritic animals. Preventive treatment of TQ and especially MTX significantly inhibited kidney dysfunction and this histopathologic alterations. These studies indicate that TQ can be used similar to MTX as a safe and effective therapy for CIA and may be useful in the treatment of rheumatoid arthritis. 相似文献
77.
78.
79.
Effects of subchronic exposure to zinc nanoparticles on tissue accumulation,serum biochemistry,and histopathological changes in tilapia (Oreochromis niloticus)
下载免费PDF全文
![点击此处可从《Environmental toxicology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Hasan Kaya Müge Duysak Mehmet Akbulut Sevdan Yılmaz Mert Gürkan Zikri Arslan Veysel Demir Mehmet Ateş 《Environmental toxicology》2017,32(4):1213-1225
Zinc nanoparticles (ZnNPs) are among the least investigated NPs and thus their toxicological effects are not known. In this study, tilapia (Oreochromis niloticus) were exposed to 1 and 10 mg/L suspensions of small size (SS, 40–60 nm) and large size (LS, 80–100 nm) ZnNPs for 14 days under semi‐static conditions. Total Zn levels in the intestine, liver, kidney, gill, muscle tissue, and brain were measured. Blood serum glucose (GLU), glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), and lactate dehydrogenase (LDH) were examined to elucidate the physiological disturbances induced by ZnNPs. Organ pathologies were examined for the gills, liver, and kidney to identify injuries associated with exposure. Significant accumulation was observed in the order of intestine, liver, kidney, and gills. Zn levels exhibited time‐ and concentration‐dependent increase in the organs. Accumulation in kidney was also dependent on particle size; NPs SS‐ZnNPs were trapped more effectively than LS‐ZnNPs. No significant accumulation occurred in the brain (p > 0.05) while Zn levels in muscle tissue increased only marginally (p ≥ 0.05). Significant disturbances were noted in serum GOT and LDH (p < 0.05). The GPT levels fluctuated and were not statistically different from those of controls (p > 0.05). Histopathological tubular deformations and mononuclear cell infiltrations were observed in kidney sections. In addition, an increase in melano‐macrophage aggregation intensity was identified on the 7th day in treatments exposed to LS‐ZnNPs. Mononuclear cell infiltrations were identified in liver sections for all treatments. Both ZnNPs caused basal hyperplasia in gill sections. Fusions appeared in the gills after the 7th day in fish treated with 10 mg/L suspensions of SS‐ZnNPs. In addition, separations in the secondary lamella epithelia were observed. The results indicated that exposure to ZnNPs could lead to disturbances in blood biochemistry and cause histopathological injuries in the tissues of O. niloticus. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1213–1225, 2017. 相似文献
80.
Fatma Yildiztekin Ebru Erol Mahmut Yildiztekin Atilla L. Tuna Mehmet Ozturk 《Pharmaceutical biology》2016,54(9):1557-1563
Context We report the first ever chemical/biochemical study on Crocus mathewii Kerndorff (Iridaceae) – a Turkish endemic angiosperm. This plant has never been explored for its phytochemistry and bioactivities.Objective This study explores C. mathewii corm and aerial parts for the chemical and biological properties of hexane, ethyl acetate, methanol and water fractions of the extracts.Material and methods Plant material (20 g) was extracted by methanol (250?mL?×?5, 3 days each) and fractioned into hexane, ethyl acetate, methanol and water. All fractions were subjected to β-carotene–linoleic acid, DPPH·, ABTS·+, CUPRAC, metal chelating and tyrosinase inhibition activities. Hexane fractions were submitted to GC–MS analysis.Results Ethyl acetate fractions showed excellent IC50 values in DPPH· (aerial 36.21?±?0.76 and corm 33.87?±?0.02?mg/L) and ABTS·+ (aerial 33.01?±?0.79 and bulb 27.87?±?0.33?mg/L); higher than the IC50 of the standard α-tocopherol (DPPH 116.25?±?1.97; ABTS 52.64?±?0.37?mg/L), higher than BHA in DPPH (57.31?±?0.25?mg/L), but slightly lower in ABTS (19.86?±?2.73?mg/L). Methanol extract of aerial parts also showed higher activity than α-tocopherol in DPPH (85.56?±?11.51?mg/L) but slightly less (72.90?±?3.66?mg/L) than both the standards in ABTS. Linoleic (aerial 53.9%, corm 43.9%) and palmitic (aerial 22.2%, corm 18%) were found as the major fatty acids.Discussion and conclusion Some fractions of C. mathewii showed higher antioxidant activities than the standards. There is a need to explore more about this plant. 相似文献