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   109168篇
  免费   7899篇
  国内免费   324篇
耳鼻咽喉   1320篇
儿科学   2734篇
妇产科学   2436篇
基础医学   13735篇
口腔科学   2227篇
临床医学   10831篇
内科学   23177篇
皮肤病学   1199篇
神经病学   10099篇
特种医学   3751篇
外国民族医学   3篇
外科学   17332篇
综合类   1546篇
现状与发展   1篇
一般理论   86篇
预防医学   9009篇
眼科学   2919篇
药学   7086篇
中国医学   163篇
肿瘤学   7737篇
  2023年   401篇
  2022年   627篇
  2021年   1786篇
  2020年   961篇
  2019年   1714篇
  2018年   2057篇
  2017年   1522篇
  2016年   1715篇
  2015年   2020篇
  2014年   2936篇
  2013年   4618篇
  2012年   6646篇
  2011年   6940篇
  2010年   3895篇
  2009年   3581篇
  2008年   6571篇
  2007年   7277篇
  2006年   6968篇
  2005年   7122篇
  2004年   6950篇
  2003年   6546篇
  2002年   6539篇
  2001年   1022篇
  2000年   879篇
  1999年   1057篇
  1998年   1405篇
  1997年   1231篇
  1996年   1081篇
  1995年   1064篇
  1994年   921篇
  1993年   826篇
  1992年   764篇
  1991年   717篇
  1990年   719篇
  1989年   634篇
  1988年   626篇
  1987年   601篇
  1986年   589篇
  1985年   650篇
  1984年   829篇
  1983年   864篇
  1982年   1066篇
  1981年   1011篇
  1980年   928篇
  1979年   534篇
  1978年   605篇
  1977年   628篇
  1976年   529篇
  1975年   485篇
  1974年   393篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
BACKGROUND: Posterior spinal procedures through tubular exposures have been described. However, tubes restrain visibility and require co-axial instrument manipulation, increasing difficulty and potentially compromising surgical results. An independent-blade retractor system overcomes the obstacles of working through a tube and has been used to perform minimally-disruptive decompression and instrumented tranforaminal lumbar interbody fusion (TLIF). PURPOSE: To evaluate the advantages to patient recovery and surgical efficacy of this technique. METHODS/RESULTS: Retrospective review of technique employing a minimally-disruptive approach to decompression and transforaminal lumber interbody fusion (TLIF). CONCLUSIONS: Minimally-disruptive decompression and instrumented TLIF can be performed in a safe and effective manner using an independent-blade retractor system. Relative to traditional-open techniques, surgical goals can be accomplished, but with the benefits of minimally-disruptive surgery.  相似文献   
42.
166Ho-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylene-phosphonate (DOTMP) is a tetraphosphonate molecule radiolabeled with 166Ho that localizes to bone surfaces. This study evaluated pharmacokinetics and radiation-absorbed dose to all organs from this beta-emitting radiopharmaceutical. METHODS: After two 1.1-GBq administrations of 166Ho-DOTMP, data from whole-body counting using a gamma-camera or uptake probe were assessed for reproducibility of whole-body retention in 12 patients with multiple myeloma. The radiation-absorbed dose to normal organs was estimated using MIRD methodology, applying residence times and S values for 166Ho. Marrow dose was estimated from measured activity retained after 18 h. The activity to deliver a therapeutic dose of 25 Gy to the marrow was determined. Methods based on region-of-interest (ROI) and whole-body clearance were evaluated to estimate kidney activity, because the radiotracer is rapidly excreted in the urine. The dose to the surface of the bladder wall was estimated using a dynamic bladder model. RESULTS: In clinical practice, gamma-camera methods were more reliable than uptake probe-based methods for whole-body counting. The intrapatient variability of dose calculations was less than 10% between the 2 tracer studies. Skeletal uptake of 166Ho-DOTMP varied from 19% to 39% (mean, 28%). The activity of 166Ho prescribed for therapy ranged from 38 to 67 GBq (1,030-1,810 mCi). After high-dose therapy, the estimates of absorbed dose to the kidney varied from 1.6 to 4 Gy using the whole-body clearance-based method and from 8.3 to 17.3 Gy using the ROI-based method. Bladder dose ranged from 10 to 20 Gy, bone surface dose ranged from 39 to 57 Gy, and doses to other organs were less than 2 Gy for all patients. Repetitive administration had no impact on tracer biodistribution, pharmacokinetics, or organ dose. CONCLUSION: Pharmacokinetics analysis validated gamma-camera whole-body counting of 166Ho as an appropriate approach to assess clearance and to estimate radiation-absorbed dose to normal organs except the kidneys. Quantitative gamma-camera imaging is difficult and requires scatter subtraction because of the multiple energy emissions of 166Ho. Kidney dose estimates were approximately 5-fold higher when the ROI-based method was used rather than the clearance-based model, and neither appeared reliable. In future clinical trials with 166Ho-DOTMP, we recommend that dose estimation based on the methods described here be used for all organs except the kidneys. Assumptions for the kidney dose require further evaluation.  相似文献   
43.
44.
OBJECTIVES: Physicians commonly use etomidate for adult rapid-sequence intubation (RSI), but the manufacturer does not recommend its use for children under 10 years of age due to a lack of data. The authors present their experience with etomidate for pediatric RSI in order to further develop its risk-benefit profile in this age group. METHODS: Trained abstractors reviewed the medical records for all children under 10 years old who received etomidate for RSI between July 1996 and April 2001. RESULTS: 105 children, with an average age of 3 (+/-2.9) years, received a median dose of 0.32 (+/-0.12) mg/kg of etomidate. The systolic blood pressure increased an average of 4 mm Hg (95% CI = -3.3 to 9.2); the diastolic blood pressure increased 7 mm Hg (95% CI = -3.1 to 11) within 10 minutes of receiving etomidate. The heart rate increased an average of 10 beats/min (95% CI = 4.0 to 17.4). Complications included three patients who vomited within 10 minutes of etomidate administration. There were no cases of documented myoclonus, status epilepticus, or new-onset seizures. Thirty-eight patients received corticosteroids during the hospital course, none for suspected adrenal insufficiency. Three patients died, all from severe brain injury. CONCLUSIONS: In children less than 10 years old, etomidate seems to produce minimal hemodynamic changes, and appears to have a low risk of clinically important adrenal insufficiency, myoclonus, and status epilepticus. The association between etomidate and emesis (observed in less than 3% of enrolled patients) remains unclear. For clinical situations in which minimal blood pressure changes during RSI are critical, etomidate appears to have a favorable risk-benefit profile for children under 10 years old.  相似文献   
45.
46.
A 19-item survey instrument was designed and mailed by the Infectious Diseases Society of America to its membership to determine the media preferred by infectious diseases physicians for continuing medical education on general topics and on antimicrobial resistance. The objective of the survey was to offer the developers of educational programs knowledge on which to base more-effective ways to deliver educational materials to physicians in this specialty.  相似文献   
47.
PURPOSE: We examined the performance of a familial risk assessment method that stratifies risk for early-onset coronary heart disease by considering the number of relatives with coronary disease, degree of relationship, lineage, and age at diagnosis. METHODS: By using data from the HealthStyles 2003 survey, we assessed the associations between familial risk and early-onset coronary heart disease, diabetes, hypercholesterolemia, hypertension, and obesity. By using area under the curve statistics, we evaluated the discriminatory ability of various risk assessment models. RESULTS: Of 4,035 respondents, 60% were female and 72% were white, with a mean age of 48.8 years. After adjustment for demographics, strong and moderate risk were significantly associated with approximately a five- and twofold risk of early-onset coronary disease, respectively. After adjustment for demographics and personal history of cardiovascular disease, strong familial risk was also significantly associated with diabetes, hypercholesterolemia, hypertension, and obesity. A risk assessment model that included familial risk, demographics, and personal history of diabetes, hypercholesterolemia, hypertension, and obesity was most optimal with an area under the curve statistic of 87.2% CONCLUSIONS: Familial risk assessment can stratify risk for early-onset coronary heart disease. Several conditions associated with increased familial risk can be prevented. These results have important implications for risk assessment and risk-reducing interventions.  相似文献   
48.
We have noted that colons of patients prepared for colonoscopy with Golytely, a nonabsorbable electrolyte lavage solution, frequently contain foam which may obscure small mucosal lesions. Therefore, a randomized, blinded controlled trial was performed to determine the prevalence of Golytely-induced foam and the effect of supplemental simethicone in decreasing the prevalence of foam. Foam was present in 32% of colons prepared with Golytely alone but in none of the colons prepared with Golytely supplemented with simethicone. In addition, only 5% of colons prepared with supplemental simethicone had residual stool noted at the time of colonoscopy, a significant improvement over the 39% prevalence of residual stool in colons prepared with Golytely alone. Addition of simethicone to Golytely lavage decreases the prevalence of colonic foam and residual stool.  相似文献   
49.
Cardiovascular calcification in end-stage renal disease.   总被引:13,自引:1,他引:12  
Cardiovascular diseases are common in patients with end-stage renal disease (ESRD) and cardiovascular morbidity and mortality among dialysis patients are substantially higher than in the general population. The reasons for this high incidence are multiple. They include traditional factors such as hypertension, diabetes, dyslipidaemia, sodium overload, and elevated homocysteine levels as well as disturbances of mineral metabolism, specifically abnormalities in phosphorus and calcium homeostasis. This review will describe the specific cardiovascular complications related to calcifications in ESRD, the implications of the abnormalities of mineral metabolism in its pathogenesis and the current imaging techniques available for the detection of cardiovascular calcifications. Excess of calcium load contributes to the development of cardiac calcifications; therefore, alternative strategies to diminish exogenous calcium load should be considered in patients with ESRD.  相似文献   
50.
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