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   3214篇
  免费   265篇
  国内免费   6篇
耳鼻咽喉   35篇
儿科学   105篇
妇产科学   79篇
基础医学   495篇
口腔科学   163篇
临床医学   436篇
内科学   509篇
皮肤病学   34篇
神经病学   399篇
特种医学   57篇
外科学   259篇
综合类   63篇
一般理论   2篇
预防医学   401篇
眼科学   13篇
药学   208篇
中国医学   1篇
肿瘤学   226篇
  2023年   18篇
  2022年   48篇
  2021年   90篇
  2020年   45篇
  2019年   74篇
  2018年   90篇
  2017年   68篇
  2016年   59篇
  2015年   79篇
  2014年   103篇
  2013年   150篇
  2012年   253篇
  2011年   255篇
  2010年   126篇
  2009年   111篇
  2008年   211篇
  2007年   185篇
  2006年   192篇
  2005年   170篇
  2004年   198篇
  2003年   155篇
  2002年   118篇
  2001年   45篇
  2000年   44篇
  1999年   46篇
  1998年   24篇
  1997年   20篇
  1996年   23篇
  1995年   12篇
  1994年   27篇
  1993年   18篇
  1992年   41篇
  1991年   31篇
  1990年   26篇
  1989年   37篇
  1988年   26篇
  1987年   26篇
  1986年   14篇
  1985年   24篇
  1984年   16篇
  1983年   22篇
  1982年   9篇
  1981年   13篇
  1980年   11篇
  1979年   9篇
  1977年   12篇
  1973年   8篇
  1972年   12篇
  1971年   7篇
  1970年   6篇
排序方式: 共有3485条查询结果,搜索用时 0 毫秒
51.
We utilized synthetic photochemistry to generate novel sp3-rich scaffolds and report the design, synthesis, and biological testing of a diverse series of amides based on the 1-(amino-methyl)-2-benzyl-2-aza-bicyclo[2.1.1]hexane scaffold. Preliminary antimalarial screening of the library provided promising compounds with activity in the 1–5 μM range with an enhanced hit rate. Further evaluation (solubility, drug metabolism and pharmacokinetics (DMPK), and toxicity) of a selected compound (9) suggested that this series represents an excellent opportunity for further optimization with the framework offering multiple opportunities for the addition of uniquely vectorally positioned extra functionality.  相似文献   
52.
53.
Cognitive dysfunction is a core feature of schizophrenia. The subtyping of cognitive performance in schizophrenia may aid the refinement of disease heterogeneity. The literature on cognitive subtyping in schizophrenia, however, is limited by variable methodologies and neuropsychological tasks, lack of validation, and paucity of studies examining longitudinal stability of profiles. It is also unclear if cognitive profiles represent a single linear severity continuum or unique cognitive subtypes. Cognitive performance measured with the Brief Assessment of Cognition in Schizophrenia was analyzed in schizophrenia patients (n = 767). Healthy controls (n = 1012) were included as reference group. Latent profile analysis was performed in a schizophrenia discovery cohort (n = 659) and replicated in an independent cohort (n = 108). Longitudinal stability of cognitive profiles was evaluated with latent transition analysis in a 10-week follow-up cohort. Confirmatory factor analysis (CFA) was carried out to investigate if cognitive profiles represent a unidimensional structure. A 4-profile solution was obtained from the discovery cohort and replicated in an independent cohort. It comprised of a “less-impaired” cognitive subtype, 2 subtypes with “intermediate cognitive impairment” differentiated by executive function performance, and a “globally impaired” cognitive subtype. This solution showed relative stability across time. CFA revealed that cognitive profiles are better explained by distinct meaningful profiles than a severity linear continuum. Associations between profiles and negative symptoms were observed. The subtyping of schizophrenia patients based on cognitive performance and its associations with symptomatology may aid phenotype refinement, mapping of specific biological mechanisms, and tailored clinical treatments.  相似文献   
54.
55.
Journal of NeuroVirology - We investigated the prevalence and risk factors for frailty among people with HIV (PWH) in rural Uganda (n = 55, 47% male, mean age 44 years)....  相似文献   
56.
Journal of Behavioral Medicine - Individuals with chronic low back pain (cLBP) frequently report sleep disturbances. Living in a neighborhood characterized by low-socioeconomic status (SES) is...  相似文献   
57.
This study compared the noninvasive assessment of left ventricular function with radionuclide angiography with that obtained with ultrasonic sonomicrometry. Left ventricular ejection fraction and rate of ventricular ejection (dV/dt) were measured with both techniques over a wide range of ventricular function. Six dogs were prepared with epicardlal crystals across the major and minor axes of the left ventricle, paired transmural wall thickness crystals and a left ventricular catheter. The animals were studied while awake after they had recovered from operation. Left ventricular volume was calculated from the ultrasonic sonomicrometric dimension measurements and the equation for a prolate ellipsoid; dV/dt was calculated from the stroke volume and ejection time. Radionuclide angiograms were performed using technetium-99m-labeled red blood cells and an Anger camera with a converging collimator interfaced to a computer programmed for multigated acquisition.A wide range of ventricular function was produced with sequential infusion of isoproterenol, propranolol, phenylepnrine and sodium thiamylal. Ejection fraction and dV/dt were measured simultaneously during each intervention using the time-activity curves of the multigated radionuclide anglogram and ultrasonic sonomicrometric dimensions. Regression analyses demonstrated a close correlation between the simultaneous measurements of ejection fraction (r values ranged from 0.95 to 0.99) and dV/dt (r values ranged from 0.87 to 0.99). these data indicate that noninvasive multigated radionuclide angiography accurately assesses changes in ejection fraction and dV/dt over a wide range of ventricular function.  相似文献   
58.
59.
Prenatal life encompasses a critical phase of human brain development, but neurodevelopmental consequences of normative differences in prenatal growth among full-term pregnancies remain largely uncharted. Here, we combine the power of a within-monozygotic twin study design with longitudinal neuroimaging methods that parse dissociable components of structural brain development between ages 3 and 30 y, to show that subtle variations of the in utero environment, as indexed by mild birth weight (BW) variation within monozygotic pairs, are accompanied by statistically significant (i) differences in postnatal intelligence quotient (IQ) and (ii) alterations of brain anatomy that persist at least into late adolescence. Greater BW within the normal range confers a sustained and generalized increase in brain volume, which in the cortical sheet, is specifically driven by altered surface area rather than cortical thickness. Surface area is maximally sensitive to BW variation within cortical regions implicated in the biology of several mental disorders, the risk for which is modified by normative BW variation. We complement this near-experimental test of prenatal environmental influences on human brain development by replicating anatomical findings in dizygotic twins and unrelated singletons. Thus, using over 1,000 brain scans, across three independent samples, we link subtle differences in prenatal growth, within ranges seen among the majority of human pregnancies, to protracted surface area alterations, that preferentially impact later-maturing associative cortices important for higher cognition. By mapping the sensitivity of postnatal human brain development to prenatal influences, our findings underline the potency of in utero life in shaping postnatal outcomes of neuroscientific and public health importance.  相似文献   
60.
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