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   2446174篇
  免费   191330篇
  国内免费   4745篇
耳鼻咽喉   34052篇
儿科学   82999篇
妇产科学   69672篇
基础医学   351353篇
口腔科学   72178篇
临床医学   217602篇
内科学   470342篇
皮肤病学   54756篇
神经病学   199315篇
特种医学   98082篇
外国民族医学   772篇
外科学   370137篇
综合类   58595篇
现状与发展   3篇
一般理论   915篇
预防医学   188191篇
眼科学   57413篇
药学   181930篇
  5篇
中国医学   4747篇
肿瘤学   129190篇
  2018年   24982篇
  2017年   19579篇
  2016年   22437篇
  2015年   25670篇
  2014年   34405篇
  2013年   52404篇
  2012年   70946篇
  2011年   74359篇
  2010年   44221篇
  2009年   41421篇
  2008年   70788篇
  2007年   75102篇
  2006年   76226篇
  2005年   74280篇
  2004年   72643篇
  2003年   69821篇
  2002年   67963篇
  2001年   110941篇
  2000年   114548篇
  1999年   96782篇
  1998年   27141篇
  1997年   24595篇
  1996年   24219篇
  1995年   23531篇
  1994年   22043篇
  1993年   20754篇
  1992年   78421篇
  1991年   76477篇
  1990年   75121篇
  1989年   72371篇
  1988年   66752篇
  1987年   66361篇
  1986年   62648篇
  1985年   60586篇
  1984年   45569篇
  1983年   38956篇
  1982年   23125篇
  1981年   20767篇
  1979年   43268篇
  1978年   30537篇
  1977年   25756篇
  1976年   24213篇
  1975年   25674篇
  1974年   31303篇
  1973年   30128篇
  1972年   27805篇
  1971年   26184篇
  1970年   24127篇
  1969年   22571篇
  1968年   20781篇
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
21.
Cyclotron-produced copper-64 radioisotope tracers offer the possibility to perform both diagnostic investigation by positron emission tomography (PET) and radiotherapy by a theranostic approach with bifunctional chelators. The versatile chemical properties of copper add to the importance of this isotope in medicinal investigation. [64Cu][Cu (ATSM)] has shown to be a viable candidate for imaging of tumor hypoxia; a critical tumor microenvironment characteristic that typically signifies tumor progression and resistance to chemo-radiotherapy. Various production and radiosynthesis methods of [64Cu][Cu (ATSM)] exist in labs, but usually involved non-standardized equipment with varying production qualities and may not be easily implemented in wider hospital settings. [64Cu][Cu (ATSM)] was synthesized on a modified GE TRACERlab FXN automated synthesis module. End-of-synthesis (EOS) molar activity of [64Cu][Cu (ATSM)] was 2.2–5.5 Ci/μmol (HPLC), 2.2–2.6 Ci/μmol (ATSM-titration), and 3.0–4.4 Ci/μmol (ICP-MS). Radiochemical purity was determined to be >99% based on radio-HPLC. The final product maintained radiochemical purity after 20 h. We demonstrated a simple and feasible process development and quality control protocols for automated cyclotron production and synthesis of [64Cu][Cu (ATSM)] based on commercially distributed standardized synthesis modules suitable for PET imaging and theranostic studies.  相似文献   
22.
23.
Gold nanoparticles (Au NPs) hold great promise in food, industrial and biomedical applications due to their unique physicochemical properties. However, influences of the gastrointestinal tract (GIT), a likely route for Au NPs administration, on the physicochemical properties of Au NPs has been rarely evaluated. Here, we investigated the influence of GIT fluids on the physicochemical properties of Au NPs (5, 50, and 100?nm) and their implications on intestinal epithelial permeability in vitro. Au NPs aggregated in fasted gastric fluids and generated hydroxyl radicals in the presence of H2O2. Cell studies showed that GIT fluids incubation of Au NPs affected the cellular uptake of Au NPs but did not induce cytotoxicity or disturb the intestinal epithelial permeability.  相似文献   
24.
Aims. Functional connectivity is providing new insights into the network nature of epilepsy with growing clinical applications. Our objective was to validate a novel magnetoencephalography‐based method to non‐invasively measure the epileptic network. Methods. We retrospectively identified pediatric and adult patients with refractory focal epilepsy who underwent pre‐surgical magnetoencephalography with subsequent intracranial electrographic monitoring. Magnetoencephalography tracings were visually reviewed, and interictal epileptiform discharges (“spikes”) were individually marked. We then evaluated differences in whole‐brain connectivity during brief epochs preceding the spikes and during the spikes using the Network‐Based Statistic to test differences at the network level. Results. In six patients with statistically‐significant network differences, we observed substantial overlap between the spike‐associated networks and electrographically active areas identified during intracranial monitoring (the spike‐associated network was 78% and 83% sensitive for intracranial electroencephalography‐defined regions in the irritative and seizure onset zones, respectively). Conclusion. These findings support the neurobiological validity of the spike‐associated network method. Assessment of spike‐associated networks has the potential to improve surgical planning in epilepsy surgery patients by identifying components of the epileptic network prior to implantation.  相似文献   
25.
ABSTRACT

Objective: Dry eye is reported to be associated with several neurological diseases. The aim of this study is to evaluate the patients with hemiplegia after stroke for dry eye and compare their results with a control group.

Materials and methods: Forty-five patients with hemiplegia and 45 individuals as the control group were included in the study. Tear function tests (Schirmer and tear breakup time) and a dry eye questionnaire for dry eye symptoms (ocular surface disease index) were performed and the results of the two groups were compared.

Results: Schirmer test results were significantly lower in the post-stroke hemiplegia group compared to the control group (11.3 ± 8.2 mm and 20.6 ± 11.6 mm, respectively, p < .001). Tear breakup time results were significantly lower in the post-stroke hemiplegia group compared to the control group (7.9 ± 3.1 s and 12.1 ± 4.3 s, respectively, p < .001). Ocular surface disease index scores were not significantly different between hemiplegia and control groups (21.6 ± 20.0 and 19.8 ± 13.9, respectively, p = .635). Schirmer scores lower than 10 mm (60% and 30%, p < .001) and tear breakup time results lower than 10 s (65.6% and 28.9%, p < .001) were also higher in the hemiplegia group compared to control group.

Conclusion: We found lower Schirmer test and tear breakup time results and similar OSDI scores in hemiplegia patients compared to controls. Hemiplegia patients may have dry eye without typical symptoms. This should be taken into consideration in the follow-up and rehabilitation of post-stroke hemiplegia patients.  相似文献   
26.
27.
28.
29.
Introduction: Pharmacovigilance is essential to monitoring the safety profiles of authorized medicines. Compared with small-molecule drugs, biological drugs are more complex, more susceptible to structural variability due to manufacturing processes, and have the potential to induce immune-related reactions, underscoring the importance of safety monitoring for these products. Although highly similar to reference products, biosimilars are not expected to be structurally identical. For these reasons, proper reporting of potential adverse drug reactions (ADRs) using distinguishable names and batch numbers is essential for accurate tracing of all biological drugs. To address the need for robust pharmacovigilance, the European Parliament and Council of the European Union provided legislation regarding pharmacovigilance of biologics in 2010.

Areas covered: This narrative review examines the current state of pharmacovigilance for biologics in the European Union (EU) and discusses relevant information on pharmacovigilance of biosimilars, the current EU pharmacovigilance system, and areas that could be improved.

Expert opinion: Although steps have been taken to improve pharmacovigilance of biologics in the EU, several enhancements can still be made, including additional training for healthcare professionals on ADR reporting, the use of 2D barcodes that enhance traceability, and an open discussion of potentially missed opportunities in the pharmacovigilance of biosimilars.  相似文献   

30.
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