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   125965篇
  免费   12450篇
  国内免费   6013篇
耳鼻咽喉   1318篇
儿科学   2494篇
妇产科学   1571篇
基础医学   14040篇
口腔科学   2344篇
临床医学   15078篇
内科学   19531篇
皮肤病学   2391篇
神经病学   6206篇
特种医学   5064篇
外国民族医学   47篇
外科学   12218篇
综合类   19532篇
现状与发展   25篇
一般理论   6篇
预防医学   10806篇
眼科学   2809篇
药学   13158篇
  101篇
中国医学   7164篇
肿瘤学   8525篇
  2024年   428篇
  2023年   1573篇
  2022年   4055篇
  2021年   5720篇
  2020年   4274篇
  2019年   3737篇
  2018年   3889篇
  2017年   3795篇
  2016年   3557篇
  2015年   5350篇
  2014年   6794篇
  2013年   7372篇
  2012年   10499篇
  2011年   10816篇
  2010年   7704篇
  2009年   6385篇
  2008年   7650篇
  2007年   7203篇
  2006年   6928篇
  2005年   5956篇
  2004年   4600篇
  2003年   4323篇
  2002年   3769篇
  2001年   2860篇
  2000年   2457篇
  1999年   1944篇
  1998年   841篇
  1997年   858篇
  1996年   646篇
  1995年   566篇
  1994年   527篇
  1993年   356篇
  1992年   718篇
  1991年   687篇
  1990年   599篇
  1989年   533篇
  1988年   532篇
  1987年   447篇
  1986年   428篇
  1985年   403篇
  1984年   285篇
  1983年   201篇
  1982年   132篇
  1981年   119篇
  1979年   222篇
  1978年   116篇
  1977年   128篇
  1976年   116篇
  1974年   137篇
  1972年   136篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Efficacy and safety of mycophenolate mofetil (MMF) may be optimized with individualized doses based on therapeutic monitoring of its active metabolite, mycophenolic acid (MPA). In this 12-month study, 137 renal allograft recipients from 11 French centers receiving basiliximab, cyclosporine A, MMF and corticosteroids were randomized to receive either concentration-controlled doses or fixed-dose MMF. A novel Bayesian estimator of MPA AUC based on three-point sampling was used to individualize doses on posttransplant days 7 and 14 and months 1, 3 and 6. The primary endpoint was treatment failure (death, graft loss, acute rejection and MMF discontinuation). Data from 65 patients/group were analyzed. At month 12, the concentration-controlled group had fewer treatment failures (p = 0.03) and acute rejection episodes (p = 0.01) with no differences in adverse event frequency. The MMF dose was higher in the concentration-controlled group at day 14 (p < 0.0001), month 1 (p < 0.0001) and month 3 (p < 0.01), as were median AUCs on day 14 (33.7 vs. 27.1 mg*h/L; p = 0.0001) and at month 1 (45.0 vs. 30.9 mg*h/L; p < 0.0001). Therapeutic MPA monitoring using a limited sampling strategy can reduce the risk of treatment failure and acute rejection in renal allograft recipients 12 months posttransplant with no increase in adverse events.  相似文献   
132.
Surgery alone has long been the standard treatment for patients with operable non-small-cell lung cancer (NSCLC). However, despite complete resection, 5-year survival rates have been disappointing, with about 50% of patients eventually suffering relapse and death from disease. Randomized trials conducted in the 1980s hinted at a survival benefit for postoperative cisplatin-based regimens, but they were underpowered. A meta-analysis published in 1995 found a nonsignificant 13% reduction in the risk of death associated with cisplatin-based chemotherapy, with an increase of survival of 5% at 5 years. This led to renewed interest in adjuvant chemotherapy in resected NSCLC. Thousands of patients have been included in a new generation of randomized trials in the last 10 years. Most of these recent studies have now been reported and several have demonstrated a clear survival advantage for patients treated with platin-based adjuvant therapy. These results also suggest a greater benefit with modern two-drug regimens. In view of the most recent data, postoperative platin-based chemotherapy can now be considered the standard of care for completely resected NSCLC patients with good performance status.  相似文献   
133.
目的 观察脂质体Dotap包裹反义脱氧寡核苷酸对酪氨酸酶(TYR)的调控效果和降解时间的影响,寻找适合于临床应用的高效转染、低降解率的载体和应用方法。方法 应用DNA合成仪合成针对TYR的反义脱氧寡核苷酸,32P标记、脂质体包埋,加入黑色素细胞培养体系进行点杂交,行黑素含量、酪氨酸酶mRNA表达量检测以及降解时间的同位素液闪检测。结果 经脂质体包埋的反义脱氧寡核苷酸使细胞黑素含量由(64±2.3)pg/cell下降至(23±1.5)pg/cell,并可使基因表达水平由160%降低至82%;同位素液闪显示经脂质体包埋的反义脱氧寡核苷酸能使其半衰期由8 h延长至12 h。结论 脂质体可以明显增强反义核酸的调控效果,并可延长其作用半衰期。  相似文献   
134.
综合实践教学模式的实施与护生综合能力的培养   总被引:3,自引:0,他引:3  
目的在《护理学基础》教学中,运用整体护理思维,探讨课堂综合实践教学模式的实效性,以提高护生的职业素质和能力。方法随机确定实验班和对照班,对照班采取传统的实践教学模式授课,实验班采取小群体综合实践模式教学。结果实验班护生的规范操作能力、沟通能力和知识运用能力与对照班比较有显著提高。结论小群体综合实践教学模式对护生综合能力的培养具有实际意义。  相似文献   
135.
Objective To explore the changes of craving and neuro-electrophysiological reactions under the exposure of heroin-related cues in abstinent heroin dependents.Methods In this self-controlled study,382 abstinent heroin dependent patients watched video of heroin smoking and injecting situations,and in the meantime were exposed to herein simulacrum and apparatus after relaxation exercises.The neuroelectrophysiological reactions were mcagured with a multi-biofeedback instrument before and after the cue exposed.Self-reported craving was also assessed before and after cue exposed.Results The craving were increased[(18±22)mm vs.(29±29)mm,P<0.01]after cue exposures compared to pre-exposure,EMG[(12±7)μN vs.(14±10)μV,P<0.01]and SC[(6.8±4.3)μS vs.(7.4±4.3)μS,P<0.01]also increased.But the percentages of δ,θ,α,SMR,low β,high β decreased compared to that under the cue exposures[8:(10.8±4.7)%vs.(9.7±4.4)%,P<0.01;0:(6.8±2.0)%vs.(6.3±2.0)%,P<0.01;α:(4.8±1.8)%vs.(4.5±1.7)%,P<0.01;SMR:(3.0 ±1.2)%vs.(2.8±1.2)%,P<0.01;low β:(2.6±1.1)%vs.(2.5±1.1)%,P<0.01 and high β:(4.6 ±1.5)%vs.(4.5±1.5)%.P<0.05].Conclusions The results indicate that drug-related cue induce heroin craving and electrophysiological reactions.  相似文献   
136.
The levels of residual radioactivity induced in Havar foils at the entrance of a high-pressure 18O-enriched water target used for the production of 18F- in a medical cyclotron with 16 MeV protons have been determined using high-resolution gamma-ray spectrometry. Whole body and skin dose rates arising from exposure to these foils during their periodic replacement have been estimated. The results indicate that irradiated foils do not represent a significant radiological hazard for the cyclotron operating staff and that no waste disposal difficulties should be encountered after an appropriate 'cooling' period of 2 years.  相似文献   
137.
Purpose: To evaluate the feasibility, reliability and analgesia effect of topical anesthesia combined with subconjunctival anesthesia in anti-glaucomatous surgery.Methods: Two hundred and four cases (357 eyes) underwent anti-glaucomatous surgeries under topical anesthesia with 0.5% Alcaine eye drops combined with subconjunctival anesthesia with 2% Lidocaine. The analgesic effect was analysed with visual analogue pain scale.Results: Among all of 357 eyes, 62 eyes underwent peripheral iridectomy, 67 eyes underwent simple trabeculectomy, 167 eyes underwent compound brabeculectomy and 12 eyes nonpenetrating trabecular surgery. The effects of anesthesia were as follows: 304 eyes (85.2%) were painless (Grade Ⅰ), 50 eyes (14.0%) were slight painful (Grade Ⅱ), and 3 eyes (0.8%) were more painful (Grade Ⅲ) during surgery. And no severe complications were observed in all the cases during surgery and postoperatively. Amaurosis fugax was not observed in the glaucoma patients at the late stage with narrow vi  相似文献   
138.
Inflammatory abnormalities may be involved in the inadequate basal oxidant/antioxidant balance and local exercise-induced oxidative stress in chronic obstructive pulmonary disease (COPD) patients. The time course of oxidative stress and inflammation was investigated in 10 COPD patients and seven healthy subjects before and after local dynamic quadriceps endurance exercise at 40% of maximal strength. Venous samples were collected before, immediately after and up to 48 h after exercise. At rest, levels of an oxidant released by stimulated phagocytes, the superoxide anion, were significantly higher in patients, as were plasma levels of C-reactive protein, tumour necrosis factor-alpha and interleukin-6, inflammatory markers. An inverse relationship was found between baseline C-reactive protein levels and endurance time in patients. Six hours after exercise, superoxide anion release and levels of protein oxidation products, an index of oxidative stress, increased similarly in both groups, whereas thiobarbituric acid reactive substance levels, another index of oxidative stress, increased significantly only in patients. Plasma nonenzymatic antioxidant and inflammatory cytokine levels were unchanged by the exercise protocol. The increased baseline systemic inflammation in chronic obstructive pulmonary disease patients could be related to disturbed oxidant/antioxidant balance, and, together, these may have triggered the exercise-induced oxidative stress. The absence, however, of local exercise-induced systemic inflammation suggests that additional mechanisms explain local exercise-induced oxidative stress.  相似文献   
139.
This study aimed to assess the ability of global and local systolic parameters measured with gated blood-pool SPECT (GBPS) to diagnose and characterize the severity of diffuse or localized arrhythmogenic right ventricular dysplasia (ARVD). METHODS: Fifty-nine subjects with symptomatic ventricular arrhythmias were prospectively included in the study. With the International Society and Federation of Cardiology criteria for ARVD as a gold standard, these subjects were classified as subjects without ARVD (21 control subjects) and patients with localized ARVD (16 patients) or diffuse ARVD (22 patients). Right ventricular volumes, right ventricular ejection fractions (EF), the SD of local EF (sigma-EF), and the SD of the local times of end systole (sigma-TES) were computed from GBPS data and compared among the groups in the study population. RESULTS: sigma-EF did not differ between control subjects and patients with diffuse or localized ARVD. Right ventricular EF and volumes differed between patients with diffuse ARVD and control subjects, with similar areas under the receiver-operating-characteristic curves, but right ventricular EF and volumes failed to differentiate patients with localized ARVD. In contrast, sigma-TES differed between patients with diffuse or localized ARVD and control subjects. Regression analysis showed that the systolic parameter most strongly associated with the diagnosis of ARVD was sigma-TES. The probabilities of a randomly chosen patient in the diffuse ARVD group and of a randomly chosen patient in the localized ARVD group having sigma-TES values greater than that of a randomly chosen control subject were 98.5% and 96.7%, respectively. For the diagnosis of localized ARVD, a threshold of 80 ms for sigma-TES corresponded to sensitivity, specificity, and positive and negative predictive values of 100%, 81%, 80%, and 100%, respectively. CONCLUSION: With GBPS, both diffuse ARVD and localized ARVD can be accurately diagnosed by computing sigma-TES for all of the pixels on the surface of the right ventricle.  相似文献   
140.
Since their discovery 40 years ago by Urist M., several studies have been done on the bone morphogenetic proteins (BMP). They belong to the superfamily of TGF β (Transforming Growth Factor) and are the only osteo-inductive growth factors known until now. They are nowadays up to 20. After the fixation of these molecules on their receptors, intracellular cell reactions occur, inducing bone formation by the activation of genes responsible for cartilaginous formation and osteogenesis. In experimental studies on animal species, BMP showed their efficiency on the recovery of bone defects, on the acceleration of fractures consolidation or spine arthrodesis fusion or on pseudarthrodesis treatment. To be efficient, BMP must be used at the proper dose and delivered locally for a sufficient period by a biocompatible and biodegradable matrix, whose tridimensional structure allows its invasion by new bone and vascular cells. According to these data, clinical trials have been conducted on the human. Only rhBMP-2 and rhBMP-7 uses are validated for definite clinical applications (vertebral fusion, tibial pseudarthrosis and open leg fracture) by the results of randomized multicentric studies. Other clinical applications have been reported in the literature but large-scale studies are still necessary to confirm their results. Even if the clinical results are sometimes spectacular, and if the use of BMP, currently reserved because of their cost, in difficult situations give rise to big hopes, many questions remain unsolved. These questions will probably be dealt with in the future: stability of the new bone formation, eventual long-term adverse effects.  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