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   74314篇
  免费   4157篇
  国内免费   584篇
耳鼻咽喉   861篇
儿科学   1371篇
妇产科学   1787篇
基础医学   9133篇
口腔科学   2963篇
临床医学   5906篇
内科学   20235篇
皮肤病学   1294篇
神经病学   7014篇
特种医学   2389篇
外科学   11583篇
综合类   247篇
一般理论   13篇
预防医学   3574篇
眼科学   1227篇
药学   4014篇
中国医学   176篇
肿瘤学   5268篇
  2023年   584篇
  2022年   519篇
  2021年   2510篇
  2020年   1467篇
  2019年   2042篇
  2018年   2625篇
  2017年   1877篇
  2016年   2072篇
  2015年   2328篇
  2014年   3106篇
  2013年   4004篇
  2012年   6144篇
  2011年   6001篇
  2010年   3371篇
  2009年   3009篇
  2008年   5025篇
  2007年   5190篇
  2006年   4786篇
  2005年   4571篇
  2004年   4127篇
  2003年   3739篇
  2002年   3275篇
  2001年   548篇
  2000年   447篇
  1999年   546篇
  1998年   601篇
  1997年   513篇
  1996年   431篇
  1995年   402篇
  1994年   333篇
  1993年   266篇
  1992年   257篇
  1991年   199篇
  1990年   187篇
  1989年   139篇
  1988年   153篇
  1987年   118篇
  1986年   117篇
  1985年   136篇
  1984年   126篇
  1983年   111篇
  1982年   134篇
  1981年   91篇
  1980年   92篇
  1979年   83篇
  1978年   76篇
  1977年   58篇
  1976年   52篇
  1974年   47篇
  1973年   55篇
排序方式: 共有10000条查询结果,搜索用时 437 毫秒
1.
2.
3.
Whereas there is evidence that interpersonal communication, or conversation, influences predictors of alcohol consumption, the role of involvement in conversation effects remains unclear. This study explored how three aspects of involvement (topical relevance, or how relevant the topic of alcohol is; conversational relevance, or how relevant a conversation about alcohol is; and conversational effort, or how much effort people put into such a conversation), influence conversation effects. After assessing topical relevance, 46 same-sex dyads were requested to talk about the negative consequences of heavy drinking. Within each dyad, one participant was asked to take on an active talking role and the other participant a passive listening role. Next, conversational relevance, effort, and predictors of heavy drinking were measured. Results showed that participants who drank more alcohol found the topic of heavy drinking more relevant. This topical relevance increased conversational relevance and conversational effort. Conversational effort further increased when a talking role was assigned. Furthermore, participants who put more effort in the conversation and found it more relevant had more positive norms, identified more strongly with alcohol, and had higher intentions to drink. These findings suggest that more involvement in an alcohol-related conversation does not always lead to desirable outcomes.  相似文献   
4.
5.
6.
Sinus venosus atrial septal defect (SV‐ASD) usually coexists with partial anomalous pulmonary vein connection (PAPVC). It is a difficult diagnosis in transthoracic echocardiography (TTE) due to eccentric position of defects. We present a rare case of atypical anatomical variation in PAPVC, which was never described before. Two right pulmonary veins drained into superior vena cava, which overrode SV‐ASD and interatrial septum, a third pulmonary vein into the right atrium. Complete diagnosis could not be set after TTE, nor transesophageal echocardiography, whereas angio‐CT was finally conclusive. This diagnostic approach allowed the surgical planning.  相似文献   
7.
In the current immunosuppressive therapy era, vessel thrombosis is the most common cause of early graft loss after renal transplantation. The prevalence of IgA anti–β2-glycoprotein I antibodies (IgA-aB2GPI-ab) in patients on dialysis is elevated (>30%), and these antibodies correlate with mortality and cardiovascular morbidity. To evaluate the effect of IgA-aB2GPI-ab in patients with transplants, we followed all patients transplanted from 2000 to 2002 in the Hospital 12 de Octubre prospectively for 10 years. Presence of IgA-aB2GPI-ab in pretransplant serum was examined retrospectively. Of 269 patients, 89 patients were positive for IgA-aB2GPI-ab (33%; group 1), and the remaining patients were negative (67%; group 2). Graft loss at 6 months post-transplant was significantly higher in group 1 (10 of 89 versus 3 of 180 patients in group 2; P=0.002). The most frequent cause of graft loss was thrombosis of the vessels, which was observed only in group 1 (8 of 10 versus 0 of 3 patients in group 2; P=0.04). Multivariate analysis showed that the presence of IgA-aB2GPI-ab was an independent risk factor for early graft loss (P=0.04) and delayed graft function (P=0.04). There were no significant differences regarding patient survival between the two groups. Graft survival was similar in both groups after 6 months. In conclusion, patients with pretransplant IgA-aB2GPI-ab have a high risk of early graft loss caused by thrombosis and a high risk of delayed graft function. Therefore, pretransplant IgA-aB2GPI-ab may have a detrimental effect on early clinical outcomes after renal transplantation.  相似文献   
8.
9.
10.
Colorectal cancer (CRC) screening programs help diagnose cancer precursors and early cancers and help reduce CRC mortality. However, currently recommended tests, the fecal immunochemical test (FIT) and colonoscopy, have low uptake. There is therefore a pressing need for screening strategies that are minimally invasive and consequently more acceptable to patients, most likely blood based, to increase early CRC identification. MicroRNAs (miRNAs) released from cancer cells are detectable in plasma in a remarkably stable form, making them ideal cancer biomarkers. Using plasma samples from FIT-positive (FIT+) subjects in an Italian CRC screening program, we aimed to identify plasma circulating miRNAs that detect early CRC. miRNAs were initially investigated by quantitative real-time PCR in plasma from 60 FIT+ subjects undergoing colonoscopy at Fondazione IRCCS Istituto Nazionale dei Tumori, then tested on an internal validation cohort (IVC, 201 cases) and finally in a large multicenter prospective series (external validation cohort [EVC], 1121 cases). For each endoscopic lesion (low-grade adenoma [LgA], high-grade adenoma [HgA], cancer lesion [CL]), specific signatures were identified in the IVC and confirmed on the EVC. A two-miRNA-based signature for CL and six-miRNA signatures for LgA and HgA were selected. In a multivariate analysis including sex and age at blood collection, the areas under the receiver operating characteristic curve (95% confidence interval) of the signatures were 0.644 (0.607–0.682), 0.670 (0.626–0.714) and 0.682 (0.580–0.785) for LgA, HgA and CL, respectively. A miRNA-based test could be introduced into the FIT+ workflow of CRC screening programs so as to schedule colonoscopies only for subjects likely to benefit most.  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