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   19269篇
  免费   1668篇
  国内免费   1385篇
耳鼻咽喉   185篇
儿科学   146篇
妇产科学   246篇
基础医学   2269篇
口腔科学   213篇
临床医学   2370篇
内科学   3391篇
皮肤病学   189篇
神经病学   926篇
特种医学   723篇
外国民族医学   11篇
外科学   2049篇
综合类   3164篇
一般理论   2篇
预防医学   1080篇
眼科学   562篇
药学   2031篇
  15篇
中国医学   964篇
肿瘤学   1786篇
  2024年   63篇
  2023年   319篇
  2022年   748篇
  2021年   963篇
  2020年   685篇
  2019年   653篇
  2018年   725篇
  2017年   575篇
  2016年   608篇
  2015年   854篇
  2014年   1049篇
  2013年   865篇
  2012年   1374篇
  2011年   1514篇
  2010年   860篇
  2009年   727篇
  2008年   1060篇
  2007年   1017篇
  2006年   975篇
  2005年   956篇
  2004年   641篇
  2003年   599篇
  2002年   518篇
  2001年   461篇
  2000年   512篇
  1999年   460篇
  1998年   344篇
  1997年   303篇
  1996年   272篇
  1995年   260篇
  1994年   170篇
  1993年   125篇
  1992年   167篇
  1991年   158篇
  1990年   127篇
  1989年   125篇
  1988年   113篇
  1987年   99篇
  1986年   96篇
  1985年   61篇
  1984年   29篇
  1983年   23篇
  1982年   11篇
  1981年   17篇
  1980年   10篇
  1979年   8篇
  1978年   7篇
  1977年   3篇
  1976年   4篇
  1974年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
The periosteum, a highly vascularized thin tissue, has excellent osteogenic and bone regenerative abilities. The generation of periosteum-mimicking tissue has become a novel strategy for bone defect repair and regeneration, especially in critical-sized bone defects caused by trauma and bone tumor resection. Here, we utilized a bone morphogenetic protein-2(BMP-2)-loaded scaffold to create periosteum-like tissue(PT) in vivo, mimicking the mesenchymal condensation during native long bone developmen...  相似文献   
72.
73.
Two cases of cervical pregnancy with heavy bleeding successfully treated by uterine artery embolization (UAE) followed by immediate curettage are described in this report. Case 1 demonstrated intermittent bleeding after serious bleeding was successfully controlled by UAE. Serum beta human chorionic gonadotropin (beta-hCG) level rose remarkably after a short time decline. Transvaginal sonography consistently revealed a heterogeneous mass in the cervix. Repeated UAE followed by immediate curettage was performed and complete resolution was achieved. Case 2 was also successfully managed by UAE followed by immediate curettage after failure of medical treatment. This report suggests that UAE followed by immediate curettage is a safe and efficient procedure for controlling heavy bleeding and avoiding recurrent bleeding when fertility capacity is desired in cases of cervical pregnancy with fetal cardiac activity and high beta-hCG concentration.  相似文献   
74.
人胃癌SGC7901细胞膜钾离子通道的特性   总被引:8,自引:0,他引:8  
目的 研究人胃癌细胞系 SGC790 1细胞膜钾离子通道特性 .方法 以人胃癌细胞系 SGC790 1为研究对象 ,采用穿孔膜片钳全细胞记录法 .结果 人的胃癌 SGC790 1细胞系的静息膜电位为 (- 32 .2± 2 .2 ) m V,在钳制电压 - 40 m V,阶跃电压在 - 80~ +80 m V,记录到一种跨膜电流 ,该跨膜电流具有电压依赖、外向整流特性 ,该电流在延迟 2 5 ms后最大激活 ,80 0 m s内不失活 ,翻转电位在 - 6 0~ - 40 m V,能被已知的钾通道的阻断剂 4- AP或 TEA阻断 .结论 在人胃癌SGC790 1细胞系细胞膜上存在延迟整流钾离子通道 .  相似文献   
75.
目的: 探讨心脏死亡供体(donation after cardiac death,DCD)原位肝移植术后胆道并发症的发生因素、诊断要点和治疗方法。方法: 对2015年1月—2016年8月于南京医科大学第一附属医院肝移植中心实施的87例DCD供肝肝移植患者临床资料进行回顾性分析。87例中29例行经典原位肝移植,58例行改良背驮式肝移植,胆管重建方式均为胆总管端端吻合,无1例放置T管。结果: 87例肝移植患者中9例通过胆道造影确诊为肝移植术后胆道并发症, 8例治愈, 1例好转, 无死亡。胆道并发症发生率10.1%(9/87)。结论: DCD供体原位肝移植术后胆道并发症的发生与供肝缺血时间、DCD供肝质量、胆管吻合技术及供肝修剪技术等因素有关,术后胆道造影有助于及时诊断胆道并发症。介入技术是胆道并发症的主要治疗手段。  相似文献   
76.
PurposeTo assess the feasibility of applying ultra-widefield fundus (UWF) images for macular staphyloma area (MSA) measurement and investigate the associated factors with MSA.MethodsThis is a retrospective study. MSA was measured by UWF imaging. Central foveal thickness, subfoveal choroidal thickness, subfoveal scleral thickness were measured on spectral domain optical coherence tomography. Intraclass correlation coefficients of MSA measurement would be evaluated. Multiple linear regression analysis was used to analyze the associated factors with MSA.ResultsIn total, 135 eyes of 92 patients were enrolled. The mean age was 64.73 ± 10.84 years. Mean MSA on UWF image was 279.67 ± 71.70 mm2. Intraclass correlation coefficients of MSA measurement was 0.965 (95% confidence interval [CI], 0.946 to 0.977; p < 0.001). In the multiple linear regression analysis, after adjusting for subfoveal choroidal thickness, best-corrected visual acuity, central foveal thickness, and subfoveal scleral thickness, the factors independently related to MSA were axial length (β = 8.352; 95% CI, 3.306 to 13.398; p = 0.001), sex (β = −26.673; 95% CI, −51.759 to −1.586; p = 0.037), age (β = 1.184; 95% CI, 0.020 to 2.348; p = 0.046).ConclusionsIt is feasible to measure MSA on UWF image. Female, longer axial length, and older age may indicate larger MSA.  相似文献   
77.
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   
78.
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   
79.
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   
80.
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   
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