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   30484篇
  免费   2010篇
  国内免费   157篇
耳鼻咽喉   264篇
儿科学   437篇
妇产科学   301篇
基础医学   4577篇
口腔科学   929篇
临床医学   2955篇
内科学   7297篇
皮肤病学   454篇
神经病学   3469篇
特种医学   1856篇
外科学   4151篇
综合类   174篇
一般理论   11篇
预防医学   1230篇
眼科学   593篇
药学   1708篇
中国医学   52篇
肿瘤学   2193篇
  2023年   246篇
  2022年   284篇
  2021年   815篇
  2020年   505篇
  2019年   705篇
  2018年   787篇
  2017年   613篇
  2016年   873篇
  2015年   989篇
  2014年   1240篇
  2013年   1524篇
  2012年   2492篇
  2011年   2504篇
  2010年   1501篇
  2009年   1345篇
  2008年   2205篇
  2007年   2213篇
  2006年   2137篇
  2005年   2008篇
  2004年   1742篇
  2003年   1643篇
  2002年   1535篇
  2001年   257篇
  2000年   190篇
  1999年   272篇
  1998年   304篇
  1997年   224篇
  1996年   163篇
  1995年   150篇
  1994年   122篇
  1993年   87篇
  1992年   60篇
  1991年   60篇
  1990年   38篇
  1989年   56篇
  1988年   35篇
  1987年   31篇
  1986年   33篇
  1985年   30篇
  1984年   28篇
  1983年   34篇
  1982年   34篇
  1981年   28篇
  1980年   26篇
  1939年   21篇
  1938年   24篇
  1937年   30篇
  1936年   25篇
  1935年   35篇
  1934年   22篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.

Background

Studies have shown patient attitudes to be an important predictor for health related behaviours including medication adherence. It is less clear whether patient attitudes are also associated with medication adherence among patients with psychoses.

Method

We conducted a systematic review and meta analysis of the data of studies that tested the association of attitude measures with medication adherence among patients with psychoses. 14 studies conducted between 1980 and 2010 were included.

Results

Results show a small to moderate mean weighted effect size (r + = 0.25 and 0.26 for Pearson and Spearman correlations, respectively).

Conclusions

Theory based interventions that target potentially modifiable attitude components are needed to assess the relationship between positive patient attitudes and adherence behaviours among patients with psychoses.  相似文献   
992.
BackgroundEvidence is lacking on remission in the presence of predominant negative symptoms.AimsTo examine remission rates and their variation by antipsychotic medication in predominant negative symptoms.MethodsData were reanalyzed on patients (n = 383) who had participated in two double blind randomized placebo-controlled clinical trials of predominant negative symptoms lasting to 84 and 360 days. Symptom remission was defined with the Remission in Schizophrenia Working Group remission criteria of attaining and maintaining mild ratings on eight SANS items. Remission rates were examined to 90 days, survival analysis computed to ascertain time to attain symptom remission, binary logistic models used to predict the remission rate and 2 persistent months of symptom remission, and ANCOVA used to predict percent time in remission.ResultsSymptomatic remission rates were: 22.72% at any visit during 90 days, and 3.66% lasting 2 months. Kaplan–Meier and Cox survival models to adjust for baseline symptom severity showed that compared with the placebo group the amisulpride group attained significantly (p < .05) more remission sooner (HR = 2.321, 95% CI = 1.36, to 3.97, p < .05). ANCOVA showed that compared with placebo the amisulpride group spent significantly (p < .05) more percent time in remission (ES = .28). Specificity analysis showed that: across trials the negative symptom remission rate was 25.1%; and in one 360-day trial the six-month remission criteria were attained and maintained by 6.4% of participants.ConclusionsPresented with predominant negative symptoms the Working Group Remission criteria appear not to be a pragmatic therapeutic objective. Modified remission symptom and time criteria may be an effective way to examine remission.  相似文献   
993.
Characterization of large‐scale brain networks using blood‐oxygenation‐level‐dependent functional magnetic resonance imaging is typically based on the assumption of network stationarity across the duration of scan. Recent studies in humans have questioned this assumption by showing that within‐network functional connectivity fluctuates on the order of seconds to minutes. Time‐varying profiles of resting‐state networks (RSNs) may relate to spontaneously shifting, electrophysiological network states and are thus mechanistically of particular importance. However, because these studies acquired data from awake subjects, the fluctuating connectivity could reflect various forms of conscious brain processing such as passive mind wandering, active monitoring, memory formation, or changes in attention and arousal during image acquisition. Here, we characterize RSN dynamics of anesthetized macaques that control for these accounts, and compare them to awake human subjects. We find that functional connectivity among nodes comprising the “oculomotor (OCM) network” strongly fluctuated over time during awake as well as anaesthetized states. For time dependent analysis with short windows (<60 s), periods of positive functional correlations alternated with prominent anticorrelations that were missed when assessed with longer time windows. Similarly, the analysis identified network nodes that transiently link to the OCM network and did not emerge in average RSN analysis. Furthermore, time‐dependent analysis reliably revealed transient states of large‐scale synchronization that spanned all seeds. The results illustrate that resting‐state functional connectivity is not static and that RSNs can exhibit nonstationary, spontaneous relationships irrespective of conscious, cognitive processing. The findings imply that mechanistically important network information can be missed when using average functional connectivity as the single network measure. Hum Brain Mapp 34:2154–2177, 2013. © 2011 Wiley Periodicals, Inc.  相似文献   
994.
Antimicrobial peptides (AMP) defend epithelial surfaces against pathological micro-organisms. We know of no comparison of their expression between the oral mucosa and extraoral epithelium, but knowledge of differences in their quantities is of interest, possibly as a starting point for new treatments. Expression of AMP human beta-defensin (hBD)-1/-2/-3 and psoriasin in the oral mucosa and extraoral epithelium of the head and neck were measured by real-time polymerase chain reaction (RT-PCR) (n=14), immunohistochemistry (n=6), and western blot (n=8). RT-PCR showed that all the genes investigated were expressed significantly more in the oral mucosa than in the skin (hBD-1: p=0.002; hBD-2: p=0.006; hBD-3: p=0.035; psoriasin: p=0.02). Immunohistochemistry and western blot showed differential concentrations of proteins: hBD-2 (p=0.021) and hBD-3 (p=0.043) were pronounced in the oral mucosa, whereas psoriasin was raised in the extraoral skin (p=0.021). There was no difference in protein concentrations for hBD-1 (p=0.08). The observed differences in the expression of AMP may be important for new treatments such as topical application of AMP derivatives.  相似文献   
995.
996.
997.
998.
Purpose: Zirconia implant abutments offer enhanced esthetics and promote biologic sealing; however, the effect of laboratory or intraoral preparation on the mechanical stability of zirconia has not been investigated. The purpose of the study was to evaluate the influence of the preparation mode and depth on the fracture strength of zirconia abutments restored with lithium disilicate crowns. Materials and Methods: To replace a maxillary central incisor (11.0 mm in height and 8.0 mm in width), 35 lithium disilicate crowns were cemented onto zirconia abutments on 4.5- ° - 15-mm titanium implants. Lithium disilicate implant crowns were divided into five study groups (n = 7) according to the abutment preparation mode (milling by the manufacturer or milling by the Celay System [Mikrona] [P]) and preparation depth (0.5 mm [A], 0.7 mm [B], or 0.9 mm [C]). All groups were subjected to quasi-static loading (S) at 135 degrees to the implant axis in a universal testing machine. Results: Mean fracture strengths were: group SA, 384 ± 84 N (control); group SB, 294 ± 95 N; group SPB, 332 ± 80 N; group SC, 332 ± 52; group SPC, 381 ± 101 N. All specimens presented a typical fracture mode within the implant/abutment internal connection. Multiple regression analysis revealed that preparation depth up to 0.7 mm statistically influenced the fracture strength (P = .034), whereas the preparation mode did not seem to play an important role (P = .175). Conclusion: Regardless of preparation mode, circumferential preparation of zirconia abutments might negatively affect the fracture strength of adhesively cemented single implant lithium disilicate crowns.  相似文献   
999.
Triethyl borane (Et3B), in combination with phosphazene-type superbases, has recently emerged as a powerful co-catalyst for the anionic polymerization of epoxides. Here, it is demonstrated that the monomer-activating property of Et3B can also compensate for the application of much gentler organobases. This not only results in simpler setups, but also significantly reduces nucleophilicity/basicity-derived side reactions. Notably, this principle applies to such a degree that simple 4-dimethylaminopyridine (DMAP) or 1,4-diazabicyclo[2.2.2]octane (DABCO) can serve to polymerize propylene oxide (PO). With suitable initiators, this results for example in very well-defined block copolyethers (ÐM ≤ 1.03) without requiring work-up to remove side products such as PPO homopolymer. Performance correlates nicely with the corresponding organobase proton affinities (PAs), and a limiting PA of 220–230 kcal mol−1 was identified for successful PO polymerization.

Mild organobases and Et3B constitute an operationally simple, user-friendly catalyst setup for polymerizing propylene oxide.  相似文献   
1000.
A critical factor for clinical practice is the production of 68Ga radiopharmaceuticals manufactured manually or through an automated procedure. 68Ga radiopharmaceuticals are often prepared manually, although this method can lead to an increased operator's radiation dose and potential variability within production. The present work compares 68Ga-radiolabelling (PSMA-11; DOTA-TOC) utilizing a cassette module (GAIA; Elysia-Raytest; Germany) with a manual setup for routine clinical production with regard to process reliability and reproducibility.  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