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   5138篇
  免费   284篇
  国内免费   96篇
耳鼻咽喉   42篇
儿科学   60篇
妇产科学   64篇
基础医学   660篇
口腔科学   151篇
临床医学   742篇
内科学   409篇
皮肤病学   33篇
神经病学   335篇
特种医学   199篇
外科学   659篇
综合类   679篇
预防医学   841篇
眼科学   109篇
药学   291篇
  12篇
中国医学   125篇
肿瘤学   107篇
  2024年   14篇
  2023年   109篇
  2022年   217篇
  2021年   317篇
  2020年   270篇
  2019年   238篇
  2018年   244篇
  2017年   195篇
  2016年   137篇
  2015年   167篇
  2014年   428篇
  2013年   366篇
  2012年   360篇
  2011年   337篇
  2010年   260篇
  2009年   241篇
  2008年   218篇
  2007年   188篇
  2006年   181篇
  2005年   147篇
  2004年   113篇
  2003年   80篇
  2002年   77篇
  2001年   66篇
  2000年   46篇
  1999年   54篇
  1998年   43篇
  1997年   46篇
  1996年   35篇
  1995年   25篇
  1994年   37篇
  1993年   25篇
  1992年   18篇
  1991年   18篇
  1990年   17篇
  1989年   7篇
  1988年   12篇
  1987年   9篇
  1986年   11篇
  1985年   17篇
  1984年   25篇
  1983年   17篇
  1982年   18篇
  1981年   15篇
  1980年   21篇
  1979年   8篇
  1978年   6篇
  1977年   3篇
  1976年   7篇
  1973年   2篇
排序方式: 共有5518条查询结果,搜索用时 15 毫秒
91.
We used a double-immunostaining technique to analyze the distribution of bcl-2+ B and T lymphocytes within the synovial membranes (SM) of 13 patients with rheumatic diseases: 11 with rheumatoid arthritis (RA), 1 with ankylosing spondylitis (AS), and 1 with osteoarthritis (OA). A high proportion (up to 50%) of the lymphocytes belonged to the B cell subset. Most of both T and B lymphocytes were positive for the bcl-2 protein. In germinal centers B lymphocytes were also negative for bcl-2 protein expression, comparable to the situation in germinal centers of secondary lymphatic organs. We conclude that bcl-2+ B lymphocytes are submitted to antigen selection in the inflamed SMs while bcl-2+ protein expression provides survival signals for their persistence in the infiltrates. The expression of bel-2 may be an important factor in protecting lymphocytes in SM from apoptosis by glucocorticoids, cytostatic drugs, and irradiation.  相似文献   
92.
During a mental rotation task of hands, participants mentally rotate their hand into the orientation of the shown hand. These mental movements are subject to the body's biomechanical constraints. In this study, we investigated whether the involvement of motor processes during the mental rotation process, as reflected in mu‐power desynchronization, is also influenced by one's movement capabilities. We performed an EEG study and used a delayed response mental rotation task of hands to examine the event‐related desynchronization differences between movements that are biomechanically easy and difficult to perform. Our results show an increase in event‐related desynchronization of the mu power for biomechanically easy compared to difficult‐to‐adopt postures. These findings provide further evidence for the notion that motor simulations can only be performed for movements that can already be performed overtly.  相似文献   
93.
94.
Introduction. Adopting another person's visuospatial perspective has been associated with empathy, which involves adopting the psychological perspective of another individual. Both reduced empathy and abnormal visuospatial processing have been observed in those with schizophrenia and schizophrenia-related personality traits. In the current study, we sought to explore the relationship between empathy, schizotypy, and visuospatial transformation ability.

Methods. 32 subjects (16 women) performed a visuospatial perspective-taking task and a mental letter rotation task. Response times and accuracy were analysed in relation to dimensions of self-reported empathy, indexed using the Interpersonal Reactivity Index, and schizotypy, as measured by the Schizotypal Personality Questionnaire.

Results. We found that: (1) greater cognitive and affective empathy were associated with reduced negative schizotypy, and, in men, greater cognitive empathy was associated with reduced positive schizotypy; (2) improved accuracy for imagined self–other transformations in the perspective-taking task was associated with greater self-reported cognitive empathy in women and higher positive schizotypy across genders; (3) faster mental letter rotation was associated with reduced cognitive empathy and increased negative schizotypy in women.

Conclusions. Together, the findings partially support the commonalities in visuospatial transformation ability, empathy, and schizotypy, and posit an interesting link between spatial manipulations of our internal representations and interactions with the physical world.  相似文献   
95.
BackgroundStudies have grouped different overhead sports and evaluated together the isokinetic strength of shoulder internal (IR) and external (ER) rotator muscles. However, muscular adaptations could be a consequence of the specific sport, and some strength imbalance between these muscles may exist as a consequence of the muscular demand unique to the sport. Therefore, grouping different overhead sports together may not be adequate.PurposeTo compare strength balance ratios between different overhead sports (volleyball, handball, swimming, judo, baseball, softball, functional movements performed at high-intensity interval training, and tennis) with a control athletic group (no overhead group).Study designCross-sectional study.MethodsA total of 237 athletes were submitted to isokinetic shoulder strength tests. The isokinetic concentric and eccentric peak torque values of shoulder internal IR and external ER rotator muscles were measured. Conventional (CR) and functional strength ratios (FR) were calculated.ResultsThere were no significant differences between the sports for the CR in the male group. Female softball athletes (90.4±13.6%) had a significantly higher CR than judo (67.3±6.9%), volleyball (74.9±15.9%), and swimming athletes (70.3±8.7%). In the female group, judo athletes had lower FR values (0.76±0.19) than soccer athletes (1.31±0.35), volleyball athletes (1.24±0.27), functional movements performed at high intensity (1.10±0.1), and softball athletes (1.40±0.39). Female handball athletes also had a lower FR (0.99±0.25) than soccer athletes (1.31±0.35) and softball athletes (1.40±0.39). Male handball (0.90±0.23), tennis (0.86±0.30), and judo (0.68±0.22) athletes had lower FR values than soccer athletes (1.20±0.21) and volleyball athletes (1.25±0.28).ConclusionsCR for males may be analyzed together, as there were no significant differences between them. However, for females, the CR for softball athletes should be analyzed individually. As there were several differences between the overhead sports according to the FRs, the authors suggest caution in grouping overhead athletes across multiple sports. These results could have important implications for the design of injury prevention and rehabilitation programs associated with the shoulder joint in overhead sports.Level of Evidence3  相似文献   
96.
目的对3种消毒剂在体检中心物体表面消毒的消毒效果及使用成本进行比较,为体检中心优选合适的物体表面消毒方式提供依据。方法分别使用I型复合双链季铵盐卫生湿巾、500mg/L含氯消毒剂、75%乙醇擦拭消毒健康体检中心采血台、彩超机和乳腺红外线诊断仪的表面,在消毒前、消毒后即刻、消毒后30min及1h分别对各区域进行棉拭子涂抹采样及培养。结果受检物体表面细菌菌落数采血台为(78.4±6.2)cfu/cm2,彩超机为(36.2±2.1)cfu/cm2,乳腺红外线诊断仪为(45.9±3.0)cfu/cm2。3种消毒剂消毒后各时间点采样菌落数与消毒前比较,差异有统计学意义(均P0.01)。I型复合双链季铵盐卫生湿巾消毒效果在消毒后即刻、消毒后30min及1h优于500mg/L含氯消毒剂、75%乙醇(P0.05,P0.01);每次消毒成本I型复合双链季铵盐卫生湿巾最低。结论 3种消毒剂对各监测表面均有良好的消毒效果,但I型复合双链季铵盐卫生湿巾的消毒持续效果优于其他两种,且使用成本低,使用方便、侵蚀性小,适用于体检中心物表消毒。  相似文献   
97.
Background and Objective: Colombia is a country of diverse geographic regions, some with mountainous terrain that can make access to urban areas difficult for individuals who live in remote areas. In 2005, a program was initiated to establish remote peritoneal dialysis (PD) centers in Colombia to improve access to PD for patients with end-stage renal disease who face geographic or financial access barriers.♦ Patients and Methods: The present study was a multi-center cohort observational study of prevalent home PD patients who were at least 18 years of age and were being managed by one of nine established remote PD centers in Colombia over a 2-year period. Data were collected from clinical records, databases, and patient interviews. Patient survival, incidence of peritonitis, and rate of withdrawal from PD therapy were assessed.♦ Results: A total of 345 patients were eligible for the study. The majority (87.8%) of patients lived on one to two times a minimum monthly salary (equivalent to US$243 – US$486). On average, patients traveled 1.2 hours and 4.3 hours from their home to their remote PD center or an urban reference renal clinic, respectively. The incidence rate of peritonitis was 2.54 episodes per 100 patient-months of therapy. A bivariate analysis showed a significantly higher risk of peritonitis in patients who were living on less than one times a monthly minimum salary (p < 0.05) or who had a dirt, cement, or unfinished wood floor (p < 0.05). The 1-year and 2-year patient survival rates were 92.44% and 81.55%, respectively. The 1-year and 2-year technique survival rates were 97.27% and 89.78%, respectively.♦ Conclusions: With the support of remote PD centers that mitigate geographic and financial barriers to healthcare, home PD therapy is a safe and appropriate treatment option for patients who live in remote areas in Colombia.  相似文献   
98.
BACKGROUND & AIMS: "Academic detailing" is an effective strategy for promoting the use of screening sigmoidoscopy by primary care physicians. The primary objectives of this study were to determine whether the sustained presence of an "outside" university-based gastroenterologist performing on-site screening sigmoidoscopy promoted long-term utilization and whether the provision for on-site sigmoidoscopy was an effective venue for training primary care endoscopists. METHODS: Nine urban community health centers, including 4 intervention and 5 control sites, participated in a nonrandomized controlled trial conducted over 3 years. RESULTS: By the end of year 3, overall self-reported use of screening sigmoidoscopy increased by 61% for the intervention group vs. only 25% for the comparison group (P = 0.001). Ninety-seven percent of those reporting compliance referred 1 or more asymptomatic average-risk patients for screening examinations. Only 2 of 83 (2.4%) eligible providers completed on-site training and continued performing screening examinations independently. The major barriers to participation included lack of interest, lack of time to learn or perform sigmoidoscopy, concerns about technical competence, and lack of need because of on-site availability. CONCLUSIONS: Maintenance of on-site screening sigmoidoscopy services performed by an outside gastroenterologist promotes long-term utilization but fails as venue for training primary care endoscopists. Alternative strategies for expanding capacity are needed.  相似文献   
99.
目的探讨消毒供应中心(CSSD)实行集中管理及全程质控的效果。方法医院加强CSSD的硬件建设,培养员工的整体素质,对手术室、全院多个专科的手术器械及消毒物品通过及时回收、清洗、消毒、包装、灭菌、储存发放,加强对外来器械的管理,严格执行各项操作流程;并成立质控小组,开展全程质控工作。结果实行集中管理一年后的各项工作质量指标与实行集中管理前比较差异有统计学意义(P0.05)。结论 CSSD只有实行集中管理及全程质控,才能为临床提供合格的无菌物品,保证医疗及护理质量。  相似文献   
100.
Motivated by the work of palaeo‐art “Double Death (2011),” a biomechanical analysis using three‐dimensional digital models was conducted to assess the potential of a pair of the large, Late Cretaceous theropod dinosaur Carcharodontosaurus saharicus to successfully lift a medium‐sized sauropod and not lose balance. Limaysaurus tessonei from the Late Cretaceous of South America was chosen as the sauropod as it is more completely known, but closely related to the rebbachisaurid sauropods found in the same deposits with C. saharicus. The body models incorporate the details of the low‐density regions associated with lungs, systems of air sacs, and pneumatized axial skeletal regions. These details, along with the surface meshes of the models, were used to estimate the body masses and centers of mass of the two animals. It was found that a 6 t C. saharicus could successfully lift a mass of 2.5 t and not lose balance as the combined center of mass of the body and the load in the jaws would still be over the feet. However, the neck muscles were found to only be capable of producing enough force to hold up the head with an added mass of 424 kg held at the midpoint of the maxillary tooth row. The jaw adductor muscles were more powerful, and could have held a load of 512 kg. The more limiting neck constraint leads to the conclusion that two, adult C. saharicus could successfully lift a L. tessonei with a maximum body mass of 850 kg and a body length of 8.3 m. Anat Rec, 298:1367–1375, 2015. © 2015 Wiley Periodicals, Inc.  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