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   3848篇
  免费   283篇
  国内免费   25篇
耳鼻咽喉   21篇
儿科学   139篇
妇产科学   106篇
基础医学   394篇
口腔科学   42篇
临床医学   660篇
内科学   709篇
皮肤病学   41篇
神经病学   256篇
特种医学   215篇
外科学   548篇
综合类   110篇
一般理论   13篇
预防医学   390篇
眼科学   101篇
药学   268篇
中国医学   3篇
肿瘤学   140篇
  2022年   30篇
  2021年   68篇
  2020年   44篇
  2019年   72篇
  2018年   57篇
  2017年   53篇
  2016年   63篇
  2015年   72篇
  2014年   90篇
  2013年   143篇
  2012年   159篇
  2011年   194篇
  2010年   122篇
  2009年   100篇
  2008年   163篇
  2007年   191篇
  2006年   172篇
  2005年   206篇
  2004年   139篇
  2003年   159篇
  2002年   127篇
  2001年   109篇
  2000年   110篇
  1999年   108篇
  1998年   55篇
  1997年   66篇
  1996年   51篇
  1995年   47篇
  1994年   52篇
  1993年   47篇
  1992年   87篇
  1991年   78篇
  1990年   78篇
  1989年   94篇
  1988年   81篇
  1987年   66篇
  1986年   47篇
  1985年   62篇
  1984年   36篇
  1983年   40篇
  1981年   24篇
  1980年   28篇
  1979年   35篇
  1978年   28篇
  1977年   23篇
  1976年   26篇
  1975年   20篇
  1974年   24篇
  1973年   25篇
  1972年   22篇
排序方式: 共有4156条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Auto-adjustable continuous positive airway pressure (APAP) devices are an emerging treatment alternative to fixed-pressure continuous positive airway pressure (CPAP) therapy for obstructive sleep apnoea syndrome. They have been engineered to automatically adjust the pressure to the optimal level on a continuous basis. However, not all APAP technologies use the same algorithm. Three different APAP devices (Autoset Spirit, Breas PV 10i and RemStar Auto) were compared in a randomised crossover trial in patients already established on fixed-pressure CPAP therapy. The outcome measures were compliance, quality of life and side-effects. Twenty-seven middle-aged patients (25 male) previously diagnosed with severe obstructive sleep apnoea syndrome (median (interquartile range) apnoea/hypopnoea index 48 (29-76)), established on CPAP therapy for >3 yrs, were randomised to each APAP device for 4 weeks. Mean pressure and patient compliance were significantly lower on the Breas PV 10i than on the other APAP devices. The devices were similar in terms of quality of life, daytime sleepiness and upper airway side-effects, but patients evaluated them significantly differently in terms of device features, sleep quality and pressure comfort, with the Breas PV 10i being the least popular. Auto-adjustable positive airway pressure devices differ in pressure delivery and patient compliance in obstructive sleep apnoea syndrome patients.  相似文献   
5.
We report the clinical and operative details of seven cases of fracture of the femoral stem of the Ring TiMESH cementless hip prosthesis (two were cemented and five uncemented). Six fractures occurred in the proximal one-third of the stem and one at mid-stem. The failures are attributed mainly to two defects in stem design, the narrowness of the anteroposterior dimensions and the depth of the recess for the titanium mesh pads. Great difficulty was experienced in removing the osseo-integrated distal fragments of the broken stems.  相似文献   
6.
Several antimicrobial drugs have been shown to pharmacokinetically interact with cyclosporine. On two separate occasions, we observed increases in cyclosporine plasma concentrations during concomitant miconazole therapy in a heart transplant patient with an infection secondary to Pseudallescheria boydii. To our knowledge, no interaction between cyclosporine and miconazole has previously been reported. In addition, drug interactions were observed between cyclosporine and ketoconazole and possibly between cyclosporine and SCH 39304, an investigational azole-antifungal agent. No interaction was noted between cyclosporine and fluconazole. In general, clinicians should anticipate drug interactions between cyclosporine and azole-antimycotic agents.  相似文献   
7.
AIMS: To determine if leucocyte volume distribution analysis (LVDA), obtained using a Coulter Counter Model S Plus IV, can be used to aid differentiation of chronic lymphoproliferative disorder (CLPD) subtypes. METHODS: Mean lymphocyte volume and lymphocyte distribution width were measured on each patient (n = 90) using a hard copy of an amplified LVDA histogram. The mean lymphocyte volume was taken as the mean of the values on either side of the peak at half maximum height. The lymphocyte distribution width was taken as the range of cell values between the two values used to calibrate the mean lymphocyte volume. A template showing typical histograms from commonly occurring CLPD was also produced on an acetate sheet. This was used to examine the histogram from each new patient to evaluate its usefulness as an alternative to the calculation of mean lymphocyte volume and lymphocyte distribution width. RESULTS: Mean lymphocyte volume and lymphocyte distribution width were significantly higher in B cell lymphocytic leukaemia of mixed cell type (B CLL/PL), B cell non-Hodgkin's lymphoma with peripheral blood spill, hairy cell leukaemia and T cell prolymphocytic leukaemia than in B cell chronic lymphocytic leukaemia (B CLL). The mean lymphocyte volume, but not the lymphocyte distribution width, was also significantly higher in T cell chronic lymphocytic leukaemia than in B CLL. The template gave an immediate preliminary indication of possible subtype(s) of disorder and could be used as an alternative to measurement of mean lymphocyte volume and lymphocyte distribution width. CONCLUSIONS: Electronic haematology analysers producing an LVDA provide a useful, cost effective cell sizing analysis which can aid the differentiation of subtypes of CLPD.  相似文献   
8.
Maternal hypercoagulability in normal pregnancy results from significant increases in blood factors that promote thrombosis or decreases in factors that inhibit thrombosis, such as antithrombin III (AT-III) and proteins C and S. The precise role of these factors in puerperal hemostasis is not clear. In 10 normal, pregnant women at term undergoing scheduled repeat cesarean section, the percent activities of AT-III, proteins C and S, and C4b-binding protein were determined in peripheral venous blood preoperatively and in samples of uterine venous blood before the uterine incision was made and 5 and 15 minutes after placental delivery using the Laurell Rocket electroimmunodiffusion technique. The mean percent activities of AT-III (73%), protein S (81%) and C4b-binding protein (85%) were lower than those in nonpregnant controls, were similar in peripheral and uterine venous blood and were unchanged after placental delivery. These data suggest that such factors may not play an important role in acute uteroplacental hemostasis during normal pregnancy.  相似文献   
9.
Recognizing the changes of medullary sponge kidney (MSK) on computed tomographic (CT) scans may be of value in both diagnosis and in differentiating this from other disease states. The appearance on CT of MSK has not previously been well described. A case is reported that demonstrates ectatic renal collecting tubules visualized by CT, and techniques are suggested to optimize visualization of these changes.  相似文献   
10.
The catechol-O-methyltransferase (COMT) Val158Met polymorphism modulates executive functions and working memory and recent neuroimaging studies implicate an association with emotional processing. We examined the relationship between the COMT Val158Met polymorphism and facial emotion recognition and differentiation in 100 healthy individuals. Compared to Met homozygosity, Val homozygosity was associated with better and faster recognition of negative facial expressions such as anger and sad. Our study provides evidence for a possible influence of the COMT polymorphism on emotion recognition abilities in healthy subjects. Additional research is needed to further define the neurocognitive phenotypes associated with COMT polymorphisms.  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