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   921篇
  免费   71篇
  国内免费   46篇
耳鼻咽喉   3篇
儿科学   56篇
妇产科学   20篇
基础医学   116篇
口腔科学   53篇
临床医学   136篇
内科学   231篇
皮肤病学   13篇
神经病学   46篇
特种医学   124篇
外科学   38篇
综合类   12篇
预防医学   54篇
眼科学   8篇
药学   72篇
  1篇
肿瘤学   55篇
  2023年   10篇
  2022年   12篇
  2021年   18篇
  2020年   17篇
  2019年   16篇
  2018年   20篇
  2017年   16篇
  2016年   18篇
  2015年   31篇
  2014年   30篇
  2013年   41篇
  2012年   25篇
  2011年   29篇
  2010年   28篇
  2009年   28篇
  2008年   24篇
  2007年   52篇
  2006年   24篇
  2005年   32篇
  2004年   26篇
  2003年   23篇
  2002年   28篇
  2001年   16篇
  2000年   18篇
  1999年   18篇
  1998年   45篇
  1997年   52篇
  1996年   56篇
  1995年   44篇
  1994年   32篇
  1993年   32篇
  1992年   4篇
  1991年   11篇
  1990年   7篇
  1989年   15篇
  1988年   24篇
  1987年   19篇
  1986年   14篇
  1985年   15篇
  1984年   6篇
  1983年   8篇
  1982年   9篇
  1981年   9篇
  1980年   11篇
  1979年   2篇
  1978年   4篇
  1977年   8篇
  1976年   2篇
  1975年   5篇
  1960年   1篇
排序方式: 共有1038条查询结果,搜索用时 15 毫秒
81.
BACKGROUND: Hospitals and blood centers throughout the United States use a variety of reagents and methods to perform pretransfusion testing. A survey was developed to determine the reagents and methods in use and their relative prevalence in different work settings. STUDY DESIGN AND METHODS: A national survey on pretransfusion testing was conducted. Surveys were distributed to state and regional blood bank associations, which then distributed them to hospitals and blood centers within their region. In most instances, the blood centers distributed the survey to the local hospitals. Completed surveys were returned to the authors for review, and all information was entered into a database for analysis. RESULTS: Analysis of the data shows that the majority of blood banks use monoclonal reagents for ABO testing and monoclonal-polyclonal blended reagents for Rh testing. The data show that anti-IgG and polyclonal antihuman globulin reagents are used almost equally for antibody screening (detection) tests and that most blood banks use a three-cell antibody-screening test. Slightly more than 50 percent of hospitals use an immediate-spin crossmatch in the absence of unexpected antibodies. CONCLUSION: A number of approved reagents and methods are used by blood bank laboratories for pretransfusion testing. Facility size (number of beds) and type tend to influence the choice of methods and reagents employed. This survey provides an opportunity for blood bank laboratories to compare their current practices with those of their peers.  相似文献   
82.
A double-blind provocative study chocolate as a trigger of headache   总被引:1,自引:0,他引:1  
A provocative double blind study of headache was performed using chocolate as the active agent and carob as the placebo. The chocolate and carob samples were formulated to duplicate products used in an earlier study (1) in which strong differential effects between the ability of chocolate and carob to trigger headache in migraine were shown. Sixty-three women with chronic headache (50% migraine, 37.5% tension-type, 12.5% combined migraine and tension-type) participated in the study. After 2 weeks of following a diet that restricted vasoactive amine-rich foods, each subject underwent double-blinded provocative trials with two samples of chocolate and two of carob presented in random order. Diaries were maintained by the subjects throughout the study, monitoring diet and headache. The results demonstrated that chocolate was not more likely to provoke headache than was carol in any of the headache diagnostic groups (2(2) 0.36, p =0.83). Interestingly, these results were independent of subjects' beliefs regarding the role of chocolate in the instigation of headache (2(1)=0.73, p =0.39). Headache diagnosis and the concomitant use of additional vasoactive amine-containing foods were also not associated with chocolate acting as a headache trigger. Thus, contrary to the commonly held belief of patients and physicians, chocolate does not appear to play a significant role in triggering headaches in typical migraine, tension-type, or combined headache sufferers.  相似文献   
83.
目的:观察胶体磷酸铬32P关节腔内注射治疗大鼠佐剂型关节炎的效果。方法:实验于2006-07/09在南京市第一医院动物实验室完成。选择6~8周龄清洁级SD雌性大鼠30只,按随机数字表法分为3组,正常对照组、模型组、胶体磷酸铬32P治疗组,每组10只。大鼠左足跖皮内注射完全弗氏佐剂0.1mL免疫法制备佐剂型关节炎模型。胶体磷酸铬32P治疗组于造模后10d左踝关节腔内注射37GBq/L胶体磷酸铬32P0.02mL,即0.74MBq,正常对照组和模型组分别给予等量生理盐水左踝关节腔内注射。①每2周观察1次大鼠左踝关节左右径宽度。②关节炎指数评定采用关节炎评分法(0~4分),分数越高,症状越重。③于用药后2,4,6周采用99Tcm-MDP显像感兴趣区分析法计算大鼠左踝关节区和右胫腓骨的放射性计数比。④于用药后4,6周测定血清肿瘤坏死因子和白细胞介素1β水平。⑤于用药后4,6周观察大鼠滑膜组织和软骨组织病理学改变。结果:纳入大鼠30只,均进入结果分析。①用药后2周模型组大鼠左踝关节左右径宽度大于正常对照组[分别为(7.82±0.36),(5.89±0.35)mm],差异有显著性意义(t=12.16,P<0.001),胶体磷酸铬32P治疗组大鼠左踝关节左右径宽度大于模型组,差异无显著性意义(P>0.05)。用药后6周胶体磷酸铬32P治疗组大鼠左踝关节左右径宽度小于模型组[分别为(6.87±0.27),(7.25±0.26)mm],差异有显著性意义(t=2.87,P<0.05)。②用药后2周和4周胶体磷酸铬32P治疗组大鼠关节炎指数高于模型组,用药后6周胶体磷酸铬32P治疗组大鼠关节炎指数低于模型组,两组间差异均无显著性意义(P>0.05)。③用药后2周模型组大鼠感兴趣区放射性计数比高于正常对照组(分别为2.05±0.20,1.46±0.15),差异有显著性意义(t=7.46,P<0.001)。用药后6周胶体磷酸铬32P治疗组大鼠感兴趣区放射性计数比低于模型组(分别为1.52±0.18,1.78±0.24),差异有显著性意义(t=2.45,P<0.05)。④用药后4,6周模型组大鼠血清肿瘤坏死因子和白细胞介素1β水平高于正常对照组,差异有显著性意义[用药后4周分别为(2.039±0.344),(1.115±0.192)μg/L;(0.305±0.034),(0.192±0.041)μg/L,t=7.42,6.71,P<0.001。用药后6周分别为(1.694±0.305),(1.126±0.256)μg/L;(0.259±0.027),(0.191±0.019)μg/L,t=4.03,5.83,P<0.01,0.001]。用药后4,6周胶体磷酸铬32P治疗组在血清肿瘤坏死因子和白细胞介素1β水平与模型组比较,差异无显著性意义(P>0.05)。⑤用药后4周胶体磷酸铬32P治疗组和模型组滑膜组织增生和炎症细胞浸润均较明显;用药后6周胶体磷酸铬32P治疗组与正常对照组比较仍有滑膜组织增生和炎症细胞浸润,与模型组比较滑膜组织增生程度明显减轻,而炎症细胞浸润程度稍轻。用药后6周胶体磷酸铬32P治疗组大鼠左踝关节的软骨组织未见有异常改变。结论:胶体磷酸铬32P关节腔注射可减轻完全弗氏佐剂免疫大鼠受注射关节的滑膜增生程度,改善关节肿胀症状,疗效肯定。  相似文献   
84.
Patients with inflammatory bowel disease have an increased frequency of thromboembolism, and microvascular thrombosis has been proposed as a contributory pathogenic factor. The mechanism of enhanced procoagulant activity is not understood. We examined the clinical setting of thromboembolic events in 52 patients with Crohn's disease or ulcerative colitis, and assessed the procoagulant laboratory profile, including Factor V Leiden, in a subset of 20 patients to identify procoagulant risk factors. Patients who developed thrombosis tended to be young; 60% of thrombotic events occurred in patients under 50 years. Multiple thromboembolic episodes occurred in 13% and unusual sites of thrombosis (e.g. intracardiac, cerebral, inominate veins) in 11%. No risk factor was identifiable in 52% of cases and two-thirds of thromboses occurred in an out-patient setting. The mortality rate was 8%. Evidence for inflammatory disease activity was found in only 45% of patients with ulcerative colitis at the time of the thromboembolic event, in contrast to 89% of those with Crohn's disease. Assays for specific coagulation defects were negative in all cases tested (protein S, C were normal in 17/17; anti-thrombin III, anti-phospholipid antibodies and activated protein C resistance were negative in 20/20, and only 1/20 patients was found to be heterozygous for Factor V leiden. Thrombosis in inflammatory bowel disease is important because it occurs in a young population, often in unusual sites, and has a high mortality. The development of thrombosis is related to active inflammatory disease in most patients with Crohn's disease but apparently not in those with ulcerative colitis. Since approximately half of the patients had no other identifiable risk factor, there remains a substantial group of patients with IBD who develop thrombosis for unknown reasons.   相似文献   
85.
86.
The potential of rapid, quantitative, and sensitive diagnosis has led to many innovative ‘lab on chip’ technologies for point of care diagnostic applications. Because these chips must be designed within strict cost constraints to be widely deployable, recent research in this area has produced extremely novel non-conventional micro- and nano-fabrication innovations. These advances can be leveraged for other biological assays as well, including for custom assay development and academic prototyping. The technologies reviewed here leverage extremely low-cost substrates and easily adoptable ways to pattern both structural and biological materials at high resolution in unprecedented ways. These new approaches offer the promise of more rapid prototyping with less investment in capital equipment as well as greater flexibility in design. Though still in their infancy, these technologies hold potential to improve upon the resolution, sensitivity, flexibility, and cost-savings over more traditional approaches.  相似文献   
87.

Background  

We recently set standards for gender-specific medicine training as an integrated part of the GP training curriculum. This paper describes the programme and evaluation of this training.  相似文献   
88.
89.

Background  

Oligoryzomys longicaudatus (colilargo) is the rodent responsible for hantavirus pulmonary syndrome (HPS) in Argentine Patagonia. In past decades (1967–1998), trends of precipitation reduction and surface air temperature increase have been observed in western Patagonia. We explore how the potential distribution of the hantavirus reservoir would change under different climate change scenarios based on the observed trends.  相似文献   
90.

Purpose

The aim of this study was to evaluate the efficacy and safety of zoledronic acid compared with placebo in preventing bone mineral density (BMD) loss and suppressing bone markers when initiated during the first year of androgen deprivation therapy in patients with locally advanced prostate cancer.

Patients and Methods

Patients were randomized to receive zoledronic acid 4 mg or placebo intravenously every 3 months. Lumbar spine (LS) and total hip BMD was measured using dual-energy x-ray absorptiometry at baseline and at week 52. N-telopeptide (NTX) and bone-specific alkaline phosphatase (BSAP) were evaluated at baseline and every 12 weeks. Safety assessments were performed throughout the study.

Results

Efficacy analyses included 106 patients and 109 patients in the zoledronic acid and placebo groups, respectively. At week 52, the least squares mean BMD percentage differences were 6.7% for LS and 3.7% for total hip (P < 0.0001 for both). In the zoledronic acid group, decreases in NTX (−14% to −28%) and BSAP (−31% to −37%) levels were significant and sustained; changes in NTX levels and LS BMD (r = −0.25; P = 0.04) and in BSAP levels and hip BMD (r = −0.28; P = 0.02) were significantly correlated. Only traumatic fractures were reported for 2 and 3 patients receiving zoledronic acid and placebo, respectively. One patient in each group experienced acute renal failure. Osteonecrosis of the jaw was not reported.

Conclusion

Zoledronic acid (4 mg intravenously every 3 months) was safe and effective in preventing bone loss and reducing bone turnover in patients with prostate cancer when initiated during the first year of androgen deprivation therapy; patients with low baseline BMD experienced the greatest benefit.  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