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   60060篇
  免费   5148篇
  国内免费   139篇
耳鼻咽喉   493篇
儿科学   2372篇
妇产科学   1563篇
基础医学   8378篇
口腔科学   1227篇
临床医学   7929篇
内科学   11644篇
皮肤病学   1032篇
神经病学   6110篇
特种医学   1612篇
外科学   6033篇
综合类   742篇
一般理论   80篇
预防医学   7037篇
眼科学   1027篇
药学   3661篇
  2篇
中国医学   63篇
肿瘤学   4342篇
  2023年   445篇
  2022年   597篇
  2021年   1491篇
  2020年   1076篇
  2019年   1635篇
  2018年   1820篇
  2017年   1418篇
  2016年   1567篇
  2015年   1679篇
  2014年   2142篇
  2013年   3123篇
  2012年   4437篇
  2011年   4540篇
  2010年   2488篇
  2009年   2183篇
  2008年   3728篇
  2007年   3824篇
  2006年   3761篇
  2005年   3546篇
  2004年   3488篇
  2003年   3131篇
  2002年   2891篇
  2001年   716篇
  2000年   600篇
  1999年   622篇
  1998年   681篇
  1997年   524篇
  1996年   481篇
  1995年   433篇
  1994年   383篇
  1993年   393篇
  1992年   465篇
  1991年   399篇
  1990年   345篇
  1989年   302篇
  1988年   306篇
  1987年   267篇
  1986年   264篇
  1985年   251篇
  1984年   219篇
  1983年   197篇
  1982年   207篇
  1981年   202篇
  1980年   195篇
  1979年   147篇
  1978年   147篇
  1977年   125篇
  1976年   131篇
  1973年   127篇
  1972年   121篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.

Aim

To evaluate the clinical and radiographic short‐term (6 months) effect of surgical treatment of peri‐implantitis, and to identify prognostic indicators affecting the outcome using a multilevel statistical model.

Materials & Methods

A total of 143 implants (45 patients) with a diagnosis of progressive peri‐implantitis (progressive bone loss (PBL) ≥2.0 mm and bleeding on probing (BoP)/suppuration) received surgical treatment. Clinical and radiographic parameters were assessed 6 months postoperatively. Potential prognostic indicators on subject, implant and site level prior to surgery were analysed to evaluate the effect on individual and composite outcomes using multilevel logistic regression analysis.

Results

At the 6‐month evaluation, none of the implants demonstrated PBL and 14% of the implants were registered with the absence of bleeding and no pocket probing depth ≥6 mm. Multilevel regression analysis identified, among others, suppuration, pocket probing depth >8 mm, bone loss >7 mm and the presence of plaque as criteria associated with the outcome.

Conclusion

Resective peri‐implantitis surgery seemed to reduce the amount of peri‐implant inflammation. However, most of the sites continued to have BoP/suppuration. Thus, long‐term maintenance and evaluation is warranted. The effect of treatment was reduced by some prognostic indicators such as the presence of suppuration prior to interception and peri‐implant bone loss exceeding 7 mm.  相似文献   
992.
The Lyra Direct strep assay was compared to culture for its ability to detect Streptococcus group A and β-hemolytic groups C/G using rapid antigen-negative pharyngeal specimens (n = 161). The Lyra assay correctly detected all β-hemolytic streptococci (group A, n = 19; group C/G, n = 5). In batch mode, the Lyra assay reduced intralaboratory turnaround time by 60% (18.1 h versus 45.0 h) but increased hands-on time by 96% (3 min 16 s versus 1 min 40 s per specimen).  相似文献   
993.
BackgroundDue to COVID-19 and high demand for respirators, some healthcare professionals have been using the Halyard H600 fabric as an alternative to N95 respirators without testing the filtration efficiency of the fabric with established scientific methods. The purpose of this study was to assess the efficiency of the Halyard H600 as a respirator filtering material as compared to the NIOSH-certified N95 and P100 filters, and determine if H600 is a good alternative for respiratory protection for healthcare professionals during the COVID-19 pandemic.MethodsThree filter types (Halyard H600, N95, and P100) were challenged with salt particles inside an exposure chamber at a flow rate of 43 LPM and relative humidity of 40 ± 2%. N95 and P100 respirator filters were tested initially to establish the validity of the chamber, followed by the Halyard H600 fabric. Particle penetration was measured using an aerosol spectrometer. The filtration efficiency was calculated for different particle sizes by measuring the particle number concentration upstream and downstream of the filter. The pressure drop across the filter materials was measured using a manometer.ResultsThe efficiency of the P100 for particles ≥250 nm was 100%. The N95 efficiency was 97 ± 1% at 275 nm, 99 ± 0% at 324 nm, and 100% for larger particles. The Halyard H600 fabric had a variable efficiency with an average of 62 ± 28% at 275 nm, 89 ± 8% at 324 nm, and 100% efficiency for particles >450 nm. The pressure drop values for P100 and N95 were 32 and 8 mmH2O, respectively. The Halyard H600 fabric resistance increased dramatically from 30 mmH2O at the start of the exposure to 65 mmH2O after 16-minutes of exposure.ConclusionThe high variability in filter efficiency for particles ≤324 nm and the increased fabric breathing resistance demonstrate that the Halyard H600 has an inferior performance and is not a good substitute for N95 and P100. Thus, the use of the Halyard H600 fabric for respiratory protection is not recommended.  相似文献   
994.
Response     
  相似文献   
995.
996.
OBJECTIVES:: The aim of this study was to determine whether visualization of the back influenced parameters of movement-related pain in people with chronic nonspecific low back pain. METHODS:: We used a randomized cross-over experiment in which 25 participants performed repeated lumbar spine movements under 2 conditions. In the visual feedback condition, patients were able to visualize their back as it moved by the use of mirrors. In the control condition, the mirror was covered so no visualization of the back was possible. RESULTS:: The average postmovement pain intensity after participants had moved with visual feedback was less (35.5±22.8 mm) than when they moved without visual feedback (44.7±26.0 mm). This difference was statistically significant (mean difference=9.3, 95% confidence interval: 2.8-15.7 F(1,22)=8.82, P=0.007). The average time to ease after participants had moved with visual feedback was shorter (44.5 s±53.8) than when they moved without visual feedback (94.4 s±80.7). This difference was also statistically significantly (mean difference=49.9, 95% confidence interval: 19.3-80.6, F(1,22)=8.82, P=0.003). DISCUSSION:: Patients with chronic nonspecific low back pain reported less increase in pain and faster resolution of pain when moving in an environment that enabled them to visualize their back. This is consistent with emerging research on the use of mirror visual feedback in other long-standing pain problems and suggests that similar lines of inquiry may be worth pursuing in the chronic nonspecific low back pain population.  相似文献   
997.
Our study is the first to compare the nasopharyngeal microbiota of pediatric pneumonia patients and control children by 454 pyrosequencing. A distinct microbiota was associated with different pneumonia etiologies. Viral pneumonia was associated with a high abundance of the operational taxonomic unit (OTU) corresponding to Moraxella lacunata. Patients with nonviral pneumonia showed high abundances of OTUs of three typical bacterial pathogens, Streptococcus pneumoniae complex, Haemophilus influenzae complex, and Moraxella catarrhalis. Patients classified as having no definitive etiology harbored microbiota particularly enriched in the H. influenzae complex. We did not observe a commensal taxon specifically associated with health. The microbiota of the healthy nasopharynx was more diverse and contained a wider range of less abundant taxa.  相似文献   
998.
Diverticular disease is common and accounts for substantial health care utilization in the USA. Recent publications in the areas of diverticulosis and diverticular disease have highlighted several notable advances that are now changing practice. Despite colonic diverticula being common, only 1–4 % of individuals with colonic diverticula will develop diverticulitis. After a first occurrence of acute diverticulitis, the risk of recurrence is 20 % at 5 years. Complications most commonly occur with the first occurrence of acute diverticulitis and not with recurrent episodes. After an episode of diverticulitis, many patients continue to experience chronic gastrointestinal symptoms. Prophylactic surgery is an option to reduce the risk of recurrence and its negative impact on quality of life. Importantly, the rationale for surgery is no longer to prevent complications because this risk is low. The review concludes with practical recommendations for patients with diverticulosis and diverticular disease.  相似文献   
999.
1000.
Ethnic and racial diversity in the United States has led to increasing interest in research on biculturalism, yet the meaning and underlying processes of biculturalism in the context of development in young adults are not well understood. Fifteen interviews were conducted with second-generation Chinese American women to explore how being bicultural fit into their lives. Data analysis yielded a developmental map that reflected their experiences throughout life as minority women. Findings suggest that biculturalism is more than being functionally competent in two cultures, it is both a behavioral and psychological orientation in life. From the findings of this study, we have increased our knowledge of Asian American women's development and provided a foundation for nursing research with minority women.  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