首页 | 官方网站   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   16496篇
  免费   934篇
  国内免费   56篇
医药卫生   17486篇
  2023年   58篇
  2021年   241篇
  2020年   163篇
  2019年   225篇
  2018年   290篇
  2017年   265篇
  2016年   322篇
  2015年   390篇
  2014年   454篇
  2013年   600篇
  2012年   832篇
  2011年   897篇
  2010年   566篇
  2009年   511篇
  2008年   884篇
  2007年   933篇
  2006年   939篇
  2005年   898篇
  2004年   844篇
  2003年   825篇
  2002年   745篇
  2001年   506篇
  2000年   424篇
  1999年   414篇
  1998年   245篇
  1997年   183篇
  1996年   175篇
  1995年   126篇
  1994年   132篇
  1993年   93篇
  1992年   199篇
  1991年   171篇
  1990年   189篇
  1989年   178篇
  1988年   149篇
  1987年   139篇
  1986年   127篇
  1985年   125篇
  1984年   94篇
  1983年   89篇
  1982年   65篇
  1981年   60篇
  1980年   72篇
  1979年   92篇
  1978年   82篇
  1977年   88篇
  1975年   63篇
  1974年   61篇
  1973年   63篇
  1972年   83篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
1.
Klawitter  Felix  Walter  Uwe  Axer  Hubertus  Ehler  Johannes 《Der Anaesthesist》2023,72(8):543-554
Die Anaesthesiologie - Die Intensive Care Unit-Acquired Weakness (ICUAW) stellt eine der häufigsten neuromuskulären Komplikationen in der Intensivmedizin dar. Besonders bei...  相似文献   
2.
Red cell exchange (RCE) is a common procedure in adults with sickle cell disease (SCD). Implantable dual lumen Vortex (DLV) ports can be used for RCE in patients with poor peripheral venous access. We performed a retrospective cohort study of RCE procedures performed in adults with SCD. The main objective of the study was to compare the inlet speed, duration of procedures and rate of complications performed through DLV ports to those performed through temporary central venous and peripheral catheters. Twenty‐nine adults with SCD underwent a total of 318 RCE procedures. Twenty adults had DLV ports placed and 218 procedures were performed using DLV ports. Mean length of follow‐up after DLV port placement was 397 ± 263 days. Six DLV ports were removed due to infection and 1 for malfunction after a mean of 171 ± 120 days. Compared to temporary central venous and peripheral catheters, DLV port procedures had a greater rate of procedural complications, a longer duration, and a lower inlet speed (all P < 0.01). When accounting for the maximum allowable inlet speed to avoid citrate toxicity, 40% of DLV port procedures were greater than 10% below maximum speed, compared to 7 and 14% of procedures performed through temporary central venous and peripheral catheters (P < 0.0001). In conclusion, DLV ports can be used for RCE in adults with SCD, albeit with more procedural complications and longer duration. The smaller internal diameter and longer catheter of DLV ports compared to temporary central venous catheters likely accounts for the differences noted. J. Clin. Apheresis 30:353–358, 2015. © 2015 Wiley Periodicals, Inc.  相似文献   
3.
4.
5.
6.
The aim of our study was to investigate the impact of the epsilon phenotype in brain glucose consumption in a population with Alzheimer’s disease. Statistical Parametric Mapping (SPM8) was used to investigate differences in brain glucose consumption (as detectable by means of 18F FDG-PET/CT) in the population examined. A total of 129 patients (72 females and 57 males) with a diagnosis of probable AD according to the NINCDS-ADRDA criteria underwent the PET/CT examination. The mean (SD) age of the patients was 70 (± 7) years; the mean Mini-Mental State Examination was 19(± 5.6). 59 expressed epsilon 4 phenotype (E4) and 70 expressed the epsilon 3 phenotype (E3). Cerebral spinal fluid amyloid, tau, and t-tau have been measured resulting equal to 367.4 (± 149.1), 584.7 (± 312.1), and 79.2(± 45.9) pg/ml, respectively. Patients with confirmed amyloid and Tau changes were classified as AD. Patients with amyloid changes but negative Tau, considered as high risk of AD, were classified as IAD. Age, sex, MMSE, scholarship, and CSF parameters were used as a covariate in the SPM analyses. We did not find significant differences in age, gender, and MMSE and CSF parameters among groups. In the analysis of the AD group as compared to AD-E3, AD-E4 subjects show a significant reduction of brain glucose consumption in inferior frontal gyrus bilaterally (BA 45, BA 47). In the analysis of the IAD group as compared to IAD-E3, IAD-E4 subjects show a significant reduction of brain glucose consumption in right in medial, middle, and superior frontal gyrus (BA10, BA11), and in left medial and middle frontal gyrus (BA10, BA11). The differences between IAD-E3 and AD-E3 and between IAD-E4 and AD-E4 (and vice versa analysis) resulted not significant. APO-e4 is related to a major involvement of the frontal cortex confirming its role of risk factor in AD, while APO-3 seems not related to a specific pattern, supporting the hypothesis of neutral/protective role in AD.  相似文献   
7.
8.
BACKGROUND AND PURPOSE: There is concern about the increase of radiation-induced malignancies with the application of modern radiation treatment techniques such as intensity-modulated radiotherapy (IMRT) and proton radiotherapy. Therefore, X-ray scatter and neutron radiation as well as the impact of the primary dose distribution on secondary cancer incidence are analyzed. MATERIAL AND METHODS: The organ equivalent dose (OED) concept with a linear-exponential and a plateau dose-response curve was applied to dose distributions of 30 patients who received radiation therapy of prostate cancer. Three-dimensional conformal radiotherapy was used in eleven patients, another eleven patients received IMRT with 6-MV photons, and eight patients were treated with spot-scanned protons. The treatment plans were recalculated with 15-MV and 18-MV photons. Secondary cancer risk was estimated based on the OED for the different treatment techniques. RESULTS: A modest increase of 15% radiation-induced cancer results from IMRT using low energies (6 MV), compared to conventional four-field planning with 15-MV photons (plateau dose-response: 1%). The probability to develop a secondary cancer increases with IMRT of higher energies by 20% and 60% for 15 MV and 18 MV, respectively (plateau dose-response: 2% and 30%). The use of spot-scanned protons can reduce secondary cancer incidence as much as 50% (independent of dose-response). CONCLUSION: By including the primary dose distribution into the analysis of radiation-induced cancer incidence, the resulting increase in risk for secondary cancer using modern treatment techniques such as IMRT is not as dramatic as expected from earlier studies. By using 6-MV photons, only a moderate risk increase is expected. Spot-scanned protons are the treatment of choice in regard to secondary cancer incidence.  相似文献   
9.
The chemical composition of the seeds of the low-alkaloid variety “Inti” of the Andean lupin (Lupinus mutabilis) grown in the south of Chile was examined. The contents of (% of dry weight) total alkaloids, protein, lipids, and oligosaccharides were found to be 0.0075, 51.0, 16.0, and 14.7%, respectively. The low levels of the sulfur amino acids (2.38% of total protein) made them the first amino acids to limit the protein quality of these lupin seeds. The fatty acid pattern was C16:0,13.9%; C18:0, 3.0%; C18:1, 41.8%; C18:2, 38.9%; and C18:3,2.6% of total fatty acids. The α-galactoside amounted to 13.5% of dry weight (raffinose, 2.49%; stachyose, 10.1%, verbascose, 0.85%). It can be stated that “Inti” is highly interesting as a potential protein energy crop for a temperate climate.  相似文献   
10.
BACKGROUND: The problems associated with rectal surgery are frequently discussed with no reference being made to the distance of the tumor from the anal verge. This study examined the effect of the location of the tumor on early postoperative results. PATIENTS AND METHODS: This was a multicenter study involving 75 German hospitals and 3756 patients, of whom 1463 had rectal carcinoma. On the basis of the location of the tumor (distance from the anal verge), four groups were distinguished: <4, 4-7.9, 8-11.9, and 12-16 cm. RESULTS: Resection and abdominoperineal resection rates and the incidence of postoperative complications depended on the location of the tumor. Significantly higher resection rates and fewer specific complications, and a significant reduction in overall postoperative morbidity were found with tumor locations more than 8 cm from the anal verge. The highest anastomotic leak rate was observed with anastomoses less than 7 cm from the anal verge. The logistic regression showed that the distance of the tumor from the anal verge is an independent variable for the development of an anastomotic leak. CONCLUSIONS: Early results are greatly affected by the location of the rectal carcinoma. This applies to both abdominoperineal resection rates and specific postoperative complications, such as anastomotic leak rate and operation morbidity in general.  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-23

京公网安备 11010802026262号