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   144433篇
  免费   7529篇
  国内免费   160篇
耳鼻咽喉   2283篇
儿科学   4859篇
妇产科学   3345篇
基础医学   21528篇
口腔科学   4698篇
临床医学   12580篇
内科学   26438篇
皮肤病学   4012篇
神经病学   14698篇
特种医学   6114篇
外科学   21926篇
综合类   653篇
一般理论   41篇
预防医学   8297篇
眼科学   3077篇
药学   9832篇
中国医学   202篇
肿瘤学   7539篇
  2023年   828篇
  2022年   540篇
  2021年   1379篇
  2020年   1282篇
  2019年   1541篇
  2018年   3124篇
  2017年   2644篇
  2016年   3440篇
  2015年   2988篇
  2014年   3357篇
  2013年   5831篇
  2012年   7373篇
  2011年   8265篇
  2010年   4844篇
  2009年   3521篇
  2008年   8368篇
  2007年   8812篇
  2006年   8534篇
  2005年   8394篇
  2004年   7882篇
  2003年   7892篇
  2002年   7782篇
  2001年   5358篇
  2000年   6792篇
  1999年   3842篇
  1998年   1573篇
  1997年   1292篇
  1996年   1008篇
  1995年   823篇
  1994年   838篇
  1993年   791篇
  1992年   863篇
  1991年   727篇
  1990年   687篇
  1989年   698篇
  1988年   617篇
  1987年   679篇
  1986年   593篇
  1985年   793篇
  1984年   747篇
  1983年   638篇
  1982年   649篇
  1981年   602篇
  1980年   558篇
  1979年   548篇
  1978年   483篇
  1977年   522篇
  1976年   440篇
  1975年   448篇
  1974年   412篇
排序方式: 共有10000条查询结果,搜索用时 781 毫秒
91.
Maximum anchorage often presents a problem that is difficult to solve during orthodontic tooth movement. Stationary, skeletal anchorage can be achieved in a simple, minimally-invasive manner, and unwanted tooth movements in opposite directions can be prevented by using transmucosally-inserted bone screws.Our initial experience using the FAMI screw as an orthodontic micro-implant proved to be clinically and histologically successful.  相似文献   
92.
The study presented here was conducted to evaluate the performance of the newly available RIDASCREEN Set (R-Biopharm AG, Darmstadt, Germany) for the detection of immunoglobulin G antibodies against Entamoeba histolytica. The sensitivity and specificity of this new enzyme-linked immunosorbent assay were evaluated using a panel of sera from 239 individuals. The assay was positive for 43 of 44 patients with invasive amebiasis, including all 18 patients with amebic liver abscess, while it was negative for 190 of 195 adult controls who were either healthy individuals or patients with other parasitic diseases. The kit was found to be highly specific (97.4%) and sensitive (97.7%) for detecting antibodies against E. histolytica in humans. Although antibody titers in patients with amebic liver abscess tend to be higher on average than in patients with invasive amebiasis, it is not possible to distinguish the two forms solely based on the results of this commercial test.  相似文献   
93.
Summary During pacemaker implantation in a patient with permanent atrial fibrillation, it remained impossible to advance a passive fixation lead with fins through the right atrium. However, a lead with a retractable screw easily passed the right atrium and was positioned in the right ventricle. Transesophageal echocardiography revealed an extensive net–like perforated Eustachian valve within the right atrium that had caused entrapment of the anchor fins during lead implantation. Remnants of embryonal structures within the right atrium should be considered a rare possible barrier during pacemaker implantation.  相似文献   
94.
PURPOSE: To compare commercial treatment-planning systems (TPS) for inverse planning (IP) and to assess constraint variations for specific IMRT indications. MATERIAL AND METHODS: For IP, OTP, XiO and BrainSCAN were used and step-and-shoot intensity-modulated radiotherapy (IMRT) delivery was assumed. Based on identical constraints, IP was performed for a prostate, head and neck, brain, and gynecologic case. IMRT plans were compared in terms of conformity/homogeneity, dose-volume histograms (DVHs), and delivery efficiency. For ten patients each of a class of indications, constraint variations were evaluated. RESULTS: IMRT plans were comparable concerning minimum target dose, homogeneity, conformity, and maximum doses to organs at risk. Larger differences were seen in dose gradients outside the target, monitor units, and segment number. Using help structures proved efficient to shape isodoses and to reduce segmentation workload. For IMRT class solutions, IP constraint variations depended on anatomic site. CONCLUSION: IP systems requiring doses as input and having objective functions based on physical parameters had a very similar performance. Constraint templates can be established for a class of IMRT indications.  相似文献   
95.
96.
97.
Gastric cancer still represents the second most common cause of gastrointestinal cancers in Germany. A disturbing issue is that at the time of diagnosis there are less than 15% of patients for whom a cure can be achieved. Nowadays, biological, histomorphological, molecular genetic and epidemiological data suggest that Helicobacter pylori eradication may lead to the prevention of gastric pre-neoplastic lesions and even gastric cancer. At present, eradication can be offered to selected patients and populations at increased risk, but more research is required before embarking on general and global H. pylori eradication for gastric cancer prevention. The main challenge is to determine how long mucosal abnormalities remain reversible and gastric cancer development can be halted.  相似文献   
98.

Background  

It is well known that physicians' night-call duty may cause impaired performance and adverse effects on subjective health, but there is limited knowledge about effects on sleep duration and recovery time. In recent years occupational stress and impaired well-being among anaesthesiologists have been frequently reported for in the scientific literature. Given their main focus on handling patients with life-threatening conditions, when on call, one might expect sleep and recovery to be negatively affected by work, especially in this specialist group. The aim of the present study was to examine whether a 16-hour night-call schedule allowed for sufficient recovery in anaesthesiologists compared with other physician specialists handling less life-threatening conditions, when on call.  相似文献   
99.
BACKGROUND: Necrotizing fasciitis (NF) is still a source of high morbidity and mortality. These difficult cases are increasingly referred to burn centers due to special wound and critical care issues. Here we examine our institution's recent experience with a large series of NF. METHOD: We performed a retrospective chart review of 32 consecutive patients over a 10-year period with NF who required radical surgical debridement and surface reconstruction. RESULTS: Overall survival was 85%, with average length of stay of 74.0+/-7.5 days for survivors (S) and 68.8+/-6.3 days for nonsurvivors (NS) (P>0.05). Time until first operation was 5.2 days in S and 3.4 days in NS (P<0.05). Patient age averaged 51.1+/-11.2 years for S and 57.0+/-12.0 years for NS (P<0.05). Survivors averaged 1.6 relevant comorbidities and NS averaged 3.6 (P<0.05). Affected total body surface (TBS) per patient averaged 6.8+/-3.3% for S and 10.2+/-5.1% for NS (P<0.05). All NS had affection of the trunk, and none of the patients with exclusive affection of extremities died. CONCLUSIONS: There were frequent delays in diagnosis and referrals to our institution, and progress can be made in educating the medical community to identify these patients. Not only the affected TBS and location but also comorbidities, age, and immediate surgical treatment are important prognostic factors. Referral to a specialized facility such as a burn center is urgently recommended for optimal surgical intervention, wound care, and critical care management.  相似文献   
100.
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