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   2953篇
  免费   231篇
  国内免费   11篇
耳鼻咽喉   33篇
儿科学   85篇
妇产科学   62篇
基础医学   380篇
口腔科学   25篇
临床医学   395篇
内科学   491篇
皮肤病学   54篇
神经病学   283篇
特种医学   63篇
外科学   317篇
综合类   58篇
一般理论   14篇
预防医学   380篇
眼科学   43篇
药学   251篇
中国医学   3篇
肿瘤学   258篇
  2023年   27篇
  2022年   11篇
  2021年   91篇
  2020年   45篇
  2019年   81篇
  2018年   112篇
  2017年   72篇
  2016年   85篇
  2015年   78篇
  2014年   109篇
  2013年   142篇
  2012年   217篇
  2011年   241篇
  2010年   101篇
  2009年   99篇
  2008年   148篇
  2007年   172篇
  2006年   139篇
  2005年   164篇
  2004年   132篇
  2003年   107篇
  2002年   109篇
  2001年   61篇
  2000年   56篇
  1999年   55篇
  1998年   29篇
  1997年   21篇
  1996年   18篇
  1995年   21篇
  1992年   26篇
  1991年   42篇
  1990年   30篇
  1989年   37篇
  1988年   30篇
  1987年   23篇
  1986年   25篇
  1985年   24篇
  1984年   15篇
  1983年   16篇
  1982年   11篇
  1981年   14篇
  1979年   18篇
  1978年   13篇
  1976年   12篇
  1972年   8篇
  1971年   16篇
  1970年   11篇
  1969年   7篇
  1968年   8篇
  1967年   9篇
排序方式: 共有3195条查询结果,搜索用时 656 毫秒
1.
2.
3.
Women with breast cancer are increasingly being cured of the disease but fatigue remains the most frequently reported symptom. The aims of our study were to identify distinct trajectories in four fatigue dimensions during 2 years after breast cancer surgery and to explore the demographic, clinical and personality characteristics associated with these profiles. We included women from the prospective longitudinal multicenter FATSEIN cohort in France. They completed the Multidimensional Fatigue Inventory for nine follow-ups over 24 months after surgery. A group-based trajectory model identified distinct trajectories in each fatigue dimension. Multinomial logistic regression determined the factors associated with each profile. From the 459 women followed, 3–5 fatigue trajectories were revealed in each fatigue dimension, from its absence to its severest degree. In our multivariate analysis, the risk of severe fatigue was decreased in all dimensions by a high quality of life before surgery (measured by the European Organization for Research and Treatment of Cancer 30-item QoL questionnaire; e.g., for general and physical fatigue: OR = 0.93, 95% CI 0.91, 0.96), especially a high physical and emotional functions for general and physical fatigue, and a high cognitive function for mental fatigue. Both severe mental fatigue and severely reduced motivation worsened with low optimism before surgery (e.g., for mental fatigue: OR = 0.93, 95% CI 0.89, 0.97). Severely reduced activities increased by having chemotherapy (OR = 9.41, 95% CI 2.28, 38.79). Targeting women at risk for severe fatigue can provide early preventive and curative treatment and appropriate psychological support.  相似文献   
4.
Background: While over half of stroke survivors recover the ability to walk without assistance, deficits persist in the performance of walking adaptations necessary for safe home and community mobility. One such adaptation is the ability to walk or step backward. Post-stroke rehabilitation rarely includes backward walking (BW) assessment and BW deficits have not been quantified in post-stroke community ambulators.

Objective: To quantify spatiotemporal and kinematic BW characteristics in post-stroke community ambulators and compare their performance to controls.

Methods: Individuals post-stroke (n = 15, 60.1 ± 12.9 years, forward speed: 1.13 ± 0.23 m/s) and healthy adults (n = 12, 61.2 ± 16.2 years, forward speed: 1.40 ± 0.13 m/s) performed forward walking (FW) and BW during a single session. Step characteristics and peak lower extremity joint angles were extracted using 3D motion analysis and analyzed with mixed-method ANOVAs (group, walking condition).

Results: The stroke group demonstrated greater reductions in speed, step length and cadence and a greater increase in double-support time during BW compared to FW (p < .01). Compared to FW, the post-stroke group demonstrated greater reductions in hip extension and knee flexion during BW (p < .05). The control group demonstrated decreased plantarflexion and increased dorsiflexion during BW, but these increases were attenuated in the post-stroke group (p < .05).

Conclusions: Assessment of BW can unmask post-stroke walking impairments not detected during typical FW. BW impairments may contribute to the mobility difficulties reported by adults post-stroke. Therefore, BW should be assessed when determining readiness for home and community ambulation.  相似文献   

5.
6.
This study examined the temporal concordance between the onset of childhood anxiety disorders and the points of onset and ending of child sexual abuse (CSA). Sexually abused children (N = 158) were assessed with structured diagnostic interviews. Onset ages for lifetime prevalence anxiety disorders were combined and sequenced with the onset and ending of sexual abuse. Hazard rates were calculated. Departures from the overall linear hazard trajectory for onsets were modeled using piecewise growth curve analyses. Increases from the overall trajectory were found around the point of sexual abuse onset for most childhood anxiety disorders. Decreases were found around the ending of sexual abuse. The risk for developing new anxiety disorders after the onset of sexual abuse showed a positive dose-effect relation with abuse severity. The findings add support to the idea that CSA can have a direct link to childhood anxiety disorders, apart from confounded vulnerability factors, postabuse events, or stable family background factors. The findings are contrasted with those from cross-sectional partial correlation studies that have suggested that there is little direct connection between sexual abuse and mental health outcomes.  相似文献   
7.
Many behavioral, immunological, and physiological consequences of brief maternal separation in bonnet (Macaca radiata) and pigtail monkeys (Macaca nemistrina) have been documented. However, the impact of social separation on plasma cortisol and growth hormone is unknown for these particular species. In the present study, the behavioral and endocrinological consequences of a 2-week maternal separation in socially housed infant bonnet and pigtail monkeys were followed. In seven pairs (separated and matched control) of bonnet and six pairs of pigtail infants, plasma was obtained under baseline, separated, and reunion conditions twice weekly for the duration of the study. Blood samples were obtained from both infants of the pair in approximately 10 min. Plasma total cortisol, free cortisol, and growth hormone were measured in these samples. Focal animal behavioral observations were made on all subjects twice daily throughout the study period. In both species, total cortisol and free cortisol rose immediately following maternal separation in comparison to the matched nonseparated controls and returned to basal levels (e.g., that of matched non-separted controls) following reunion with the mother. In contrast, plasma growth hormone rose only in the pigtail infants over a time course that peaked around the time of reunion. Multiple regression techniques indicated for the first week of separation, in the separated but not control subjects, that mean plasma free and total cortisol was positively related to distress behaviors (vocalization and postural slouch) observed during this week and negatively related to social behaviors (play and proximity to others) noted during the same period. In contrast, plasma growth hormone was related to both species and sex of the subjects but unrelated to behavioral variables. © 1995 John Wiley & Sons, Inc.  相似文献   
8.
A series of 73 dibenzo[a,d]cycloalkenimines were synthesized and evaluated for their ability to displace (+)-10,11-dihydro-5-methyl-5H-dibenzo[a,d]cyclohepten-5,10-imine ([3H]-(+)-10) from its specific binding site on rat cortical membranes. A number of the more active compounds (Ki ranging from 0.006 to 0.21 microM) were evaluated for N-methyl-D-aspartate (NMDA) antagonist activity in the rat cortical slice (Kb ranging from 0.08 to 0.9 microM) and anticonvulsant activity in the mouse against NMDA induced convulsions. The ED50 values ranged from 0.22 to 7.76 mg/kg and correlated reasonably well with the Kb determination. In the dibenzo[a,d]cyclohepten-5,10-imine series, the (+)-5S,10R enantiomer displayed consistently higher levels of biological activity. While substitution at the 3-position of (+)-10 with electronegative atoms generally increased in vitro activity, a loss of potency relative to (+)-10 (MK-801) was observed in vivo for all of the compounds tested.  相似文献   
9.
The junctional zone (Jz) of the mouse placenta consists of two main trophoblast populations, spongiotrophoblasts and glycogen cells (GCs), but the development and function of both cell types are unknown. We conducted a quantitative analysis of GC size, number, and invasion of cells into the decidua across gestation. Furthermore, we identified markers of GC function to investigate their possible roles in the placenta. While the spongiotrophoblast cell volume doubles, and cell number increases steadily from E12.5 to E16.5, there is a remarkable 80-fold increase in GC numbers. This finding is followed by a notable decrease by E18.5. Surprisingly, the accumulation of GCs in the decidua did not fully account for the decrease in GC number in the Jz, suggesting loss of GCs from the placenta. Glucagons were detected on GCs, suggesting a steady glucose release throughout gestation. Connexin31 staining was shown to be specific for GCs. GC migration and invasion may be facilitated by temporally regulated expression of matrix metalloproteinase 9 and the imprinted gene product, Decorin. Expression of the clearance receptor for type II insulin-like growth factor (IGF-II), IGF2R, in a short developmental window before E16.5 may be associated with regulating the growth effects of IGF-II from glycogen cells and/or labyrinthine trophoblast on the expansion of the Jz. Thus stereology and immunohistochemistry have provided useful insights into Jz development and function of the glycogen cells.  相似文献   
10.
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