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   32131篇
  免费   1997篇
  国内免费   231篇
耳鼻咽喉   433篇
儿科学   590篇
妇产科学   482篇
基础医学   3965篇
口腔科学   1538篇
临床医学   2586篇
内科学   8538篇
皮肤病学   382篇
神经病学   3290篇
特种医学   1278篇
外科学   5208篇
综合类   92篇
一般理论   6篇
预防医学   1296篇
眼科学   532篇
药学   1688篇
中国医学   72篇
肿瘤学   2383篇
  2023年   331篇
  2022年   275篇
  2021年   933篇
  2020年   729篇
  2019年   991篇
  2018年   1182篇
  2017年   956篇
  2016年   1038篇
  2015年   1118篇
  2014年   1444篇
  2013年   1762篇
  2012年   2770篇
  2011年   2668篇
  2010年   1496篇
  2009年   1361篇
  2008年   2141篇
  2007年   2252篇
  2006年   2023篇
  2005年   1841篇
  2004年   1639篇
  2003年   1493篇
  2002年   1294篇
  2001年   254篇
  2000年   232篇
  1999年   217篇
  1998年   190篇
  1997年   170篇
  1996年   125篇
  1995年   136篇
  1994年   123篇
  1993年   105篇
  1992年   114篇
  1991年   93篇
  1990年   79篇
  1989年   54篇
  1988年   85篇
  1987年   61篇
  1986年   44篇
  1985年   63篇
  1984年   52篇
  1983年   43篇
  1982年   43篇
  1981年   28篇
  1980年   24篇
  1979年   41篇
  1978年   30篇
  1977年   22篇
  1974年   21篇
  1973年   30篇
  1972年   26篇
排序方式: 共有10000条查询结果,搜索用时 17 毫秒
1.
In the last decade, the development of new radiopharmaceuticals for the imaging and therapy of prostate cancer has been a highly active and important area of research, especially focusing on the prostate-specific membrane antigen (PSMA), an antigen which is upregulated in prostate, as well as in other tumor cells. A large variety of PSMA ligands have been radiolabeled, to date. Among the various derivatives, PSMA-617 resulted to be one of the most interesting in terms of interaction with the antigen and clinical properties, and its lutetium-177 labeled version has recently been approved by regulatory agencies for therapeutic purposes. For this reasons, the radiolabeling with fluorine-18 of a PSMA-617 derivative might be of interest. Beside other methodologies to radiolabel macromolecules with fluorine-18, the “click-chemistry” approach resulted to be very useful, and the copper-catalyzed azide-alkyne cycloaddition (CuAAC) is considered one of most efficient and reliable. This paper proposes the synthesis of a suitable precursor for the radiolabeling with fluorine-18 of a new PSMA-617 derivative. The whole radiosynthetic procedure has been fully automated, and the final product, which proved to be stable in plasma, has been obtained with radiochemical yield and purity suitable for subsequent preclinical studies.  相似文献   
2.
The notarium is a rigid bony structure, which resulted from the fusion of thoracic vertebrae of some pterosaurs and birds. It is high variable, ranging from two to six fused thoracic vertebrae. In this study, we reviewed and analyzed approximately 270 specimens of neornithine birds (representing 80% of the living orders) and some fossils in order to identify the number of fused vertebrae, degree and sites of vertebral fusion, occurrence of sutures, and other structures of potential phylogenetic and functional significance. These data were analyzed using a recent time-calibrated molecular phylogenetic tree and principal component analyses analysis evaluating the relationship with long bones in order to reconstruct macroevolutionary trends related to the evolution of the notarium. The occurrence of this structure shows a mosaic distribution over neornithine phylogeny, originating several times independently, especially during the Paleogene, in predominantly ground-dwelling forms. The notarium of these groups is characterized by: neural spines fused into single structure, intervertebral openings small to absent, large ventral keels forming ventral plates, and fused transverse processes. Derived neornithines, such as aquatic forms and long-legged birds, have a tendency to display a decreased degree of fusion between the vertebrae, which may indicate a reduction or disappearance of the notarium.  相似文献   
3.
Emergency Radiology - In subarachnoid hemorrhage, noncontrast CT features are used to guide the localization of ruptured aneurysms on CT angiography and DSA. Multiplanar CT may improve the...  相似文献   
4.
Malignant melanoma (MM) is a highly aggressive neoplasm with a growing worldwide incidence. It is not uncommon that the disease is already metastatic at the time of the first diagnosis. Regional lymph nodes and skin are the first and most common metastatic sites, followed by distant visceral sites (lungs, liver, and central nervous system) and bone. In this clinical setting, fine-needle aspiration (FNA) often represents the first diagnostic approach. FNA is a useful tool to obtain a rapid and accurate diagnosis, in conjunction with ancillary techniques and molecular analysis, as recommended by recent guidelines. The aim of this review was to describe the cytomorphology, immunocytochemical tools, and molecular tools used for the diagnosis of MM metastases on FNA.  相似文献   
5.
Cardiovascular Drugs and Therapy - The clinical course of COVID-19 may be complicated by acute respiratory distress syndrome (ARDS) and thromboembolic events, which are associated with high risk of...  相似文献   
6.
Heart Failure Reviews - To compare the efficacy and safety of different mechanical circulatory support (MCS) devices in CS. A total of 24 studies (7 randomized controlled...  相似文献   
7.
Clinical Rheumatology - Osteitis condensans ilii (OCI) is a benign condition characterised by triangular sclerosis of the iliac bone which may mimic radiographic sacroiliitis. Prevalence is...  相似文献   
8.
Inflammopharmacology - To examine the effectiveness of Janus-kinase inhibitors (JAKis) or abatacept (ABA) in patients with rheumatoid arthritis-interstitial lung disease (RA-ILD). Patients with...  相似文献   
9.
This study aimed to assess depression, anxiety, posttraumatic stress disorder (PTSD) and discrimination in African migrants and investigate determinants. A cross-sectional study was conducted in Italy (July 2019–February 2020). Inclusion criteria: being a citizen of an African country or having parents who are citizens of an African country. Questionnaires included tests for depression, anxiety, PTSD, discrimination. Multivariable regressions were performed. Participants were 293. The prevalence of depression, anxiety, and PTSD was: 12.1%, 12.1%, and 24.4%. Only 7.2% declared not to be discriminated. Among significantly associated factors, waiting for/being in possession of temporary permits and discrimination were associated with all mental outcomes. Being (or having parents from) Sub-Saharan Africa increased the likelihood of discrimination. A relevant prevalence of mental illnesses was reported. Particularly, Sub-Saharan Africans potentially offer a unique point of view. Migrants' mental health should be a priority for national and international programs of health monitoring.  相似文献   
10.
Malignant pleural mesothelioma (MPM) is a rare and aggressive cancer mainly caused by asbestos exposure. Specific and sensitive noninvasive biomarkers may facilitate and enhance screening programs for the early detection of cancer. We investigated DNA methylation (DNAm) profiles in MPM prediagnostic blood samples in a case-control study nested in the European Prospective Investigation into Cancer and nutrition (EPIC) cohort, aiming to characterise DNAm biomarkers associated with MPM. From the EPIC cohort, we included samples from 135 participants who developed MPM during 20 years of follow-up and from 135 matched, cancer-free, controls. For the discovery phase we selected EPIC participants who developed MPM within 5 years from enrolment (n = 36) with matched controls. We identified nine differentially methylated CpGs, selected by 10-fold cross-validation and correlation analyses: cg25755428 (MRI1), cg20389709 (KLF11), cg23870316, cg13862711 (LHX6), cg06417478 (HOOK2), cg00667948, cg01879420 (AMD1), cg25317025 (RPL17) and cg06205333 (RAP1A). Receiver operating characteristic (ROC) analysis showed that the model including baseline characteristics (age, sex and PC1wbc) along with the nine MPM-related CpGs has a better predictive value for MPM occurrence than the baseline model alone, maintaining some performance also at more than 5 years before diagnosis (area under the curve [AUC] < 5 years = 0.89; AUC 5-10 years = 0.80; AUC >10 years = 0.75; baseline AUC range = 0.63-0.67). DNAm changes as noninvasive biomarkers in prediagnostic blood samples of MPM cases were investigated for the first time. Their application can improve the identification of asbestos-exposed individuals at higher MPM risk to possibly adopt more intensive monitoring for early disease identification.  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