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   19374篇
  免费   1684篇
  国内免费   1412篇
耳鼻咽喉   185篇
儿科学   165篇
妇产科学   249篇
基础医学   2297篇
口腔科学   231篇
临床医学   2329篇
内科学   3441篇
皮肤病学   197篇
神经病学   929篇
特种医学   742篇
外国民族医学   11篇
外科学   2065篇
综合类   3170篇
一般理论   2篇
预防医学   1081篇
眼科学   562篇
药学   2038篇
  15篇
中国医学   961篇
肿瘤学   1800篇
  2024年   63篇
  2023年   317篇
  2022年   746篇
  2021年   959篇
  2020年   674篇
  2019年   655篇
  2018年   730篇
  2017年   578篇
  2016年   614篇
  2015年   857篇
  2014年   1053篇
  2013年   873篇
  2012年   1371篇
  2011年   1510篇
  2010年   866篇
  2009年   728篇
  2008年   1047篇
  2007年   1010篇
  2006年   976篇
  2005年   966篇
  2004年   644篇
  2003年   591篇
  2002年   523篇
  2001年   468篇
  2000年   515篇
  1999年   463篇
  1998年   364篇
  1997年   321篇
  1996年   286篇
  1995年   271篇
  1994年   184篇
  1993年   128篇
  1992年   169篇
  1991年   161篇
  1990年   130篇
  1989年   130篇
  1988年   117篇
  1987年   104篇
  1986年   105篇
  1985年   65篇
  1984年   29篇
  1983年   23篇
  1982年   13篇
  1981年   19篇
  1980年   11篇
  1979年   7篇
  1978年   10篇
  1977年   6篇
  1976年   8篇
  1975年   5篇
排序方式: 共有10000条查询结果,搜索用时 16 毫秒
81.
We spectroscopically investigated coordination state of Fe3+ in methanol (MeOH) and ethanol (EtOH) solutions against Cl concentration ([Cl]). In both the system, we observed characteristic absorption bands due to the FeCl4 complex at high-[Cl] region. In the MeOH system, the proportion (r) of [FeCl4] exhibits a stationary value of 0.2–0.3 in the intermediate region of 10 mM < [Cl] < 50 mM, which is interpretted in terms of [FeClnL6−n]3−n (n = 1 and 2). In the EtOH system, r steeply increases from 0.1 at [Cl] = 1.5 mM to 0.7 at [Cl] = 3.5 mM, indicating direct transformation from [FeL6]3+ to [FeCl4]. We further found that the coordination change significantly decreases the redox potential of Fe2+/Fe3+.

Fe3+ coordination in alcohol solution can be controlled by the Cl concentration ([Cl]). The coordination state changes from FeL6 (L: solvent molecule) to FeCl4 type via FeClnL6−n with increases in [Cl].  相似文献   
82.
ContextValerian extract capsule (VEC) is an effective Chinese patent medicine used for gastrointestinal (GI) diseases.ObjectiveTo investigate the detailed pharmacological activity for VEC clinical effects in GI diseases.Materials and methodsSprague-Dawley rats were divided into six groups: control, model, and drug-treated (VEC-L, VEC-M, VEC-H, and teprenone). Rats were orally administered VEC (124, 248, 496 mg/kg) and teprenone (21.43 mg/kg) for 3 consecutive days. After 1 h, the five groups (except the control group) were orally given ethanol (10 mL/kg) for 1 h or indomethacin (80 mg/kg) for 7 h. The spasmolytic activity of VEC (0.01–1 mg/mL) on ACh/BaCl2-induced New Zealand rabbit smooth muscle contraction was performed. The C57BL/6 mice carbon propelling test evaluated the effects of VEC (248–992 mg/kg) on intestinal motility in normal and neostigmine/adrenaline-induced mice.ResultsCompared with the model group, VEC treatment reduced the gastric lesion index and mucosal damage. Further experiments showed that the pathological ameliorative effect of VEC was accompanied by augmentation of the enzymatic antioxidant system and cytoprotective marker (COX-1, p < 0.01; PGI2 p < 0.05;), along with the alleviation of the levels of MPO (ethanol: 15.56 ± 0.82 vs. 12.15 ± 2.60, p < 0.01; indomethacin: 9.65 ± 3.06 vs. 6.36 ± 2.43, p < 0.05), MDA (ethanol: 1.66 ± 0.44 vs. 0.81 ± 0.58, p < 0.01; indomethacin: 1.71 ± 0.87 vs. 1.09 ± 0.43, p < 0.05), and inflammatory mediators. VEC decreased the high tone induced by ACh/BaCl2 and promoted intestinal transit in normal and neostigmine/adrenaline-induced mice.Discussion and conclusionsVEC showed a potential gastroprotective effect, suggesting that VEC is a promising phytomedicine for the treatment of GI diseases.  相似文献   
83.
ObjectiveThis study was performed to examine the relationship between the C-reactive protein/albumin ratio (CAR) and the prognosis of patients with lung adenocarcinoma and thus provide a reference for evaluating the prognosis of lung adenocarcinoma.MethodsThe clinical data of 130 patients with lung adenocarcinoma were retrospectively collected and analyzed. The patients’ overall survival (OS) time was calculated, and the factors affecting OS were statistically analyzed.ResultsThe CAR was correlated with sex, clinical stage, brain metastasis, S100 calcium-binding protein B (S100B), interleukin 17, myelin basic protein, squamous cell carcinoma antigen (SCC-Ag), and the lymphocyte count. The median OS was significantly shorter in the high- than low-CAR group (18 vs. 64 months, respectively). The CAR, clinical stage, brain metastasis, S100B, interleukin 17, SCC-Ag, C-reactive protein, albumin, and neutrophil count affected the OS of patients with lung adenocarcinoma. The CAR and clinical stage were independent risk factors for a poor prognosis in patients with lung adenocarcinoma.ConclusionsThe CAR and clinical stage are independent risk factors for OS in patients with lung adenocarcinoma.  相似文献   
84.
Solid epoxy resin is highly desired in adhesives, electronic materials and coatings due to the attractive characteristics of solvent-free, highly efficient utilization and convenient storage and transportation. However, the challenges remain in fabricating high-toughness solid epoxy resin through a facile and efficient way. Here, a high-performance environment-friendly solid epoxy resin was fabricated by employing maleic anhydride grafted ethylene-vinyl acetate copolymer (EVA-g-MAH) as the flexibilizer via one-step banburying method. The results showed that the modified epoxy resin maintained a high glass transition temperature (Tg) and thermal stability, while its impact strength, tensile toughness and flexural toughness were significantly increased compared with the neat epoxy resin. The impact strength, tensile toughness and flexural toughness of R-EM10 are improved 138%, 195% and 149%, respectively. The EVA-g-MAH was introduced in the epoxy matrix as a separate phase to increase toughness via transfer stress and dissipated energy. The attractive properties of this facile fabrication process and the high-toughness, as well as the environment-friendly performance make this solid epoxy highly promising for large-scale industrial application.

High-toughness and environment-friendly solvent free solid epoxy resin through a low-cost, facile and large-scale fabrication process.  相似文献   
85.
In order to improve the corrosion resistance of the automotive AM60B-Mg alloy, a nano-SiO2/MAO composite coating was prepared on the surface of the alloy. The electrochemical properties were studied in an 80 °C corrosion environment using potentiodynamic polarization tests. Local Electrochemical Impedance Spectroscopy (LEIS) was used to study the corrosion mechanisms of coating defect zone. The microstructure and phase of the samples were observed by confocal laser microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Macroscopic electrochemical test results showed that the impedance of the nano-SiO2/MAO coating was much higher than that of the MAO coating, by about 433 times. Local electrochemical test results showed that the minimum impedance of the nano-SiO2/MAO coating was 1–2 orders of magnitude higher than the maximum impedance of the MAO coating. The defective SiO2/MAO coating still had high corrosion resistance compared to the defective MAO coating. A physical model of local corrosion mechanisms was proposed.  相似文献   
86.
BackgroundPityriasis rosea (PR) is a papulosquamous eruption with generally unknown origin but suspected to be related to viral etiologies. The clinicopathological spectrum of several disorders with viral etiologies has been altered after the coronavirus disease 2019 (COVID-19) pandemic. The author group could experience coherent histological alterations in PR after the COVID-19 pandemic. This study aimed to investigate how the clinicopathological findings of PR were changed after the COVID-19 pandemic.MethodsPatients (n = 11) diagnosed with PR based on the clinical manifestations and skin biopsies between February 2018 and October 2019 and 11 patients in February 2020 and October 2021 were retrospectively analyzed by investigating the medical records.ResultsThe patients with PR during the COVID-19 pandemic demonstrated statistically significant histopathological alterations from classic brisk and dense infiltration pattern to dormant and sparse infiltration and psoriasiform-dominant patterns (P = 0.019). PR was associated with more frequent pruritus during the pandemic period (P = 0.027).ConclusionIn conclusion, PR demonstrated a significant histopathological alteration with more frequent pruritus during the COVID-19 pandemic. The comparative results about clinicopathological findings of PR will provide a useful reference for dermatologists in the diagnostic process of PR in the COVID-19 pandemic.  相似文献   
87.
ObjectiveThis study aims to assess the proportions of complex regional pain syndrome type I (CRPS I) in radial head fracture patients undergoing unilateral arthroplasty and to explore associated factors.MethodsThis is a prospective observational study. From March 2016 to May 2019, a total of 221 adult patients with radial head fracture patients were included in consecutive studies and completed the 1‐year follow‐up. All patients were treated by unilateral arthroplasty. At each follow‐up visit, the visual analogue scale was used to measure patients'' pain level. Occurrence of CRPS I, which was diagnosed by Budapest criteria, was the main outcome collected at baseline and the 1‐, 3‐, 6‐, and 9‐month follow‐ups. The baseline data were collected before surgery and included demographic and clinical data. Independent t‐tests and χ 2 tests were used as univariate analyses to compare the baseline data of patients with and without CRPS I. Multivariate analysis (Backword‐Wald) was used to identify factors independently associated with CRPS I.ResultsThe proportion of CRPS I cases among radial head fracture patients undergoing unilateral arthroplasty was 11% (n = 24). A total of 19 (79%) patients were diagnosed with CRPS I within 1 month after surgery. Multivariable logistic regression analysis revealed that female gender (odds ratios [OR]: 1.537; 95% confidence interval [CI]: 1.138–2.072), age younger than 60 years (OR: 1.682; 95% CI: 1.246–2.267), moderate and severe Mayo Elbow Performance Score (MEPS) pain (OR: 3.229; 95% CI: 2.392–4.351) and anxiety (OR: 83.346; 95% CI: 61.752–112.320) were independently associated with CRPS I.ConclusionsThis exploratory study reported that the incidence of CRPS I developing after radial head arthroplasty was 11%. Female sex, younger age, moderate and severe MEPS pain and anxiety patients seems more likely to develop CRPS I.  相似文献   
88.
Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ALL) is a high-risk disease subtype with a dismal prognosis. Inhibiting BCR-ABL kinase alone is insufficient to eradicate Ph+ALL clones, and alternative BCR-ABL-dependent and -independent pathways need to be targeted as an effective strategy. Our study revealed that the combination of dasatinib and interferon-α showed synergistic activity against Ph+ALL, inducing mitochondrial dysfunction and causing necrosis-like cell lysis. Mechanistic studies showed that the induced cell death was caspase-3-independent. Canonical necroptosis signals, such as RIP1 and MLKL, were not activated; instead, the pyroptosis executor Gasdermin D was upregulated expression and activated. The expression levels of extracellular ATP and IL-1β were also upregulated, both of which are markers of pyroptotic cell death. In a murine Ph+ALL model, the dual drug treatment prolonged the survival of tumor-bearing mice. More importantly, we incorporated the dual drugs to maintenance therapy in 39 patients who were unfit for allogeneic stem cell transplantation (allo-HSCT). The median follow-up was 28.5 months, the 4-year disease-free survival and overall survival rates were 52.2% and 65.2%, respectively. Our data suggest that the combination of dasatinib and interferon-α has potential synergistic activity against Ph+ALL and shows promise as a maintenance therapy for Ph+ALL patients who are unfit for allo-HSCT.  相似文献   
89.
目的 探讨瞬时弹性记录仪(FibroScan)检测肝脏受控衰减参数(CAP)诊断非酒精性脂肪性肝炎(NASH)的效能.方法 2016年1月~2020年1月我院收治的NASH患者142例和同期健康体检者130例,使用FibroScan检测肝脏CAP值.采用受试者工作特征曲线(ROC)并计算曲线下面积(AUC)评价CAP值...  相似文献   
90.
Objective: This study aimed to evaluate the prognostic value of preoperative radiomics and establish an integrated model for esophageal squamous cell cancer(ESCC).Methods: A total of 931 patients were retrospectively enrolled in this study(training cohort, n=624; validation cohort, n=307). Radiomics features were obtained by contrast-enhanced computed tomography(CT) before esophagectomy. A radiomics index was set based on features of tumor and reginal lymph nodes by using the least absolute shri...  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