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   3155篇
  免费   251篇
  国内免费   24篇
耳鼻咽喉   50篇
儿科学   71篇
妇产科学   140篇
基础医学   525篇
口腔科学   48篇
临床医学   382篇
内科学   657篇
皮肤病学   111篇
神经病学   257篇
特种医学   102篇
外科学   281篇
综合类   69篇
预防医学   162篇
眼科学   76篇
药学   246篇
中国医学   16篇
肿瘤学   237篇
  2023年   19篇
  2022年   36篇
  2021年   92篇
  2020年   57篇
  2019年   91篇
  2018年   103篇
  2017年   88篇
  2016年   79篇
  2015年   122篇
  2014年   147篇
  2013年   194篇
  2012年   253篇
  2011年   272篇
  2010年   169篇
  2009年   144篇
  2008年   222篇
  2007年   196篇
  2006年   175篇
  2005年   152篇
  2004年   136篇
  2003年   116篇
  2002年   95篇
  2001年   72篇
  2000年   41篇
  1999年   63篇
  1998年   29篇
  1997年   19篇
  1996年   14篇
  1995年   7篇
  1994年   14篇
  1993年   6篇
  1992年   12篇
  1991年   21篇
  1990年   20篇
  1989年   15篇
  1988年   27篇
  1987年   16篇
  1986年   16篇
  1985年   10篇
  1984年   16篇
  1983年   4篇
  1981年   5篇
  1980年   5篇
  1979年   8篇
  1978年   4篇
  1977年   4篇
  1975年   3篇
  1974年   5篇
  1971年   4篇
  1969年   2篇
排序方式: 共有3430条查询结果,搜索用时 15 毫秒
71.
72.
Precise regulation of bone resorption is critical for skeletal homeostasis. We report a 32‐year‐old man with a panostotic expansile bone disease and a massive hemorrhagic mandibular tumor. Originally from Mexico, he was deaf at birth and became bow‐legged during childhood. There was no family history of skeletal disease. Puberty occurred normally, but during adolescence he experienced difficulty straightening his limbs, sustained multiple fractures, and developed a bony tumor on his chin. By age 18 years, all limbs were misshapen. The mandibular mass grew and protruded from the oral cavity, extending to the level of the lower ribs. Other bony defects included a similar maxillary mass and serpentine limbs. Upon referral at age 27 years, biochemical studies showed serum alkaline phosphatase of 1760 U/L (Nl: 29‐111) and other elevated bone turnover markers. Radiography of the limbs showed medullary expansion and cortical thinning with severe bowing. Although the jaw tumors were initially deemed inoperable, mandibular mass excision and staged partial maxillectomy were eventually performed. Tumor histopathology showed curvilinear trabeculae of woven bone on a background of hypocellular fibrous tissue. Fibrous dysplasia of bone was suspected, but there was no mutation in codon 201 of GNAS in samples from blood or tumor. His clinical and radiographic findings, elevated serum markers, and disorganized bone morphology suggested amplified receptor activator of NF‐κB (RANK) signaling, even though his disorder differed from conditions with known constitutive activation of RANK signaling (eg, familial expansile osteolysis). We found a unique 12‐base pair duplication in the signal peptide of TNFRSF11A, the gene that encodes RANK. No exon or splice site mutations were found in the genes encoding RANK ligand or osteoprotegerin. Alendronate followed by pamidronate therapies substantially decreased his serum alkaline phosphatase activity. This unique patient expands the phenotypes and genetic basis of the mendelian disorders of RANK signaling activation. © 2014 American Society for Bone and Mineral Research.  相似文献   
73.
In recent years, interventional cardiologists have discussed over a new clinical issue called longitudinal stent compression (LSC), a failure mode not previously observed in coronary stents. This phenomenon occurs when the physician attempts to cross a deployed stent with a second device, causing the stent to dramatically shorten when two devices are accidentally entangled. While this phenomenon has been observed with a number of stent platforms, it seems more common with the Element stent. In this paper, a computational LSC model using finite element analysis was developed. A systematic investigation was conducted in attempts to quantify individual contribution of the stent design pattern, connector number, design parameter, and connector location on LSC. Computational simulations were performed on two representative coronary stents resembling Element and Endeavor for comparison. Simulation results show that the connector number plays the most significant role in LSC. The LSC could be easily tripled or quadrupled for the same stent design simply by increasing the connector number from two to three. The design pattern and design parameter play a secondary role in LSC, with the LSC improved by up to 30 and 65 %, respectively. It was also found that the LSC could be doubled for the Element stent simply by rearranging its connector location. This small design tweak could help improve the current Element LSC significantly, while still maintaining the majority of its excellent deliverability. These findings could provide great insights into this new clinical issue and help optimize future stent design to reduce the associated risk involved in LSC.  相似文献   
74.
Benign tumours of the submandibular gland are usually treated surgically. Gland-preserving techniques, which can be used to completely remove the tumour, preserve the function of the gland and reduce complications, but conventional open operations result in obvious scars on the neck. We aimed to investigate the feasibility and efficacy of gland-preserving robotic surgery using a hairline approach. We compared robotic with open techniques for gland-preserving operations to remove benign tumours of the submandibular gland. Patients were matched for age and sex (4 in each group). All patients in the robotic surgery group had their tumours removed successfully through hairline approaches. No patient had operative complications or postoperative functional nerve deficit, and an aesthetically pleasing outcome was achieved by concealing the scars within the hairline. Robotic operations took longer than open operations. No recurrence was noted during follow-up. Gland-preserving robotic surgery is a feasible alternative to conventional techniques and has potential advantages for safety and aesthetic outcome.  相似文献   
75.
76.
77.
Web forums become the means of online communication and information sharing sources for the learning about health care and related treatment knowledge. By adopting web crawlers and natural language processing techniques, the automatic identification approach of the concerned HIV-related messages is proposed to facilitate the health authorities and social support groups in instant counseling. The proposed supervised GA/k-means for classification approach can help construct an effective identification and classification model with acceptable classification performance accompanied with its full flexibility to develop different fitness functions in accordance with the need of different requirements. Furthermore, with the aid of correspondence analysis, the most frequently used terms in concerned HIV-related messages are identified and focus on risky sexual behavior whereas unconcerned messages are those who of worried well.  相似文献   
78.
A large number of putative risk genes for autism spectrum disorder (ASD) have been reported.The func-tions of most of these susceptibility genes in developing b...  相似文献   
79.
80.
Background: The prevalence of mental health concerns among university students in the United States (U.S.) continues to increase, while current treatments, including medication and counseling, present shortcomings. Higher dairy and calcium intakes are associated with protective effects on mental health; however, previous studies have focused on investigating singular relationships between dairy and calcium intakes and mental health measures. A more complex exploration of these relationships is warranted to better examine whether increasing dairy and calcium intakes could serve as an intervention to improve mental health. The present study sought to further characterize the relationships between dairy and calcium intake, perceived stress, and a variety of mental health measures using linear regression and moderation analyses. Methods: The present cross-sectional study involved students studying at three large U.S. universities, and data collection occurred from April to May 2020 when students were learning remotely due to the COVID-19 pandemic. An online survey comprising validated tools was distributed among students to assess dairy and calcium intake, perceived stress, anxiety, negative and positive moods, rumination, and resilience, sleep quality and duration, dietary risk, and physical activity. Results: A total of 1233 students completed the study. Higher dairy and calcium intake was coincident with lower perceived stress and higher positive mood scores, while higher calcium intake was also coincident with lower anxiety, rumination, and higher resilience scores. Additionally, as calcium intake increased, the relationship between perceived stress and anxiety and the relationship between perceived stress and negative mood weakened. Dairy intake did not have this effect. Conclusions: Based on the results, and considering that calcium is a shortfall nutrient, universities should consider initiating programs and public health campaigns to promote dairy and calcium intake among this population.  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