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   768篇
  免费   51篇
  国内免费   74篇
耳鼻咽喉   13篇
儿科学   14篇
妇产科学   7篇
基础医学   75篇
口腔科学   2篇
临床医学   103篇
内科学   203篇
皮肤病学   4篇
神经病学   89篇
特种医学   104篇
外科学   84篇
综合类   20篇
一般理论   1篇
预防医学   48篇
眼科学   32篇
药学   56篇
中国医学   3篇
肿瘤学   35篇
  2023年   11篇
  2022年   11篇
  2021年   20篇
  2020年   17篇
  2019年   19篇
  2018年   22篇
  2017年   9篇
  2016年   16篇
  2015年   14篇
  2014年   18篇
  2013年   35篇
  2012年   22篇
  2011年   34篇
  2010年   27篇
  2009年   20篇
  2008年   26篇
  2007年   72篇
  2006年   30篇
  2005年   34篇
  2004年   21篇
  2003年   35篇
  2002年   32篇
  2001年   17篇
  2000年   25篇
  1999年   15篇
  1998年   22篇
  1997年   24篇
  1996年   24篇
  1995年   22篇
  1994年   9篇
  1993年   10篇
  1992年   14篇
  1991年   13篇
  1990年   13篇
  1989年   23篇
  1988年   20篇
  1987年   12篇
  1986年   10篇
  1985年   8篇
  1984年   13篇
  1983年   10篇
  1982年   6篇
  1981年   3篇
  1980年   5篇
  1979年   2篇
  1978年   8篇
  1977年   8篇
  1975年   2篇
  1947年   1篇
  1946年   1篇
排序方式: 共有893条查询结果,搜索用时 15 毫秒
41.
42.
In a prospective study of 65 patients with bile duct obstruction, various radiologic modalities were compared for their capability to demonstrate the level and cause of obstruction and to indicate accurately tumor resectability. Ultrasound (US) was performed in 65 patients, computed tomography (CT) in 51, direct cholangiography (DC) in 57, and angiography in 35. The level of obstruction was correctly indicated by US in 95% of patients and by CT in 90%, and the cause was correctly indicated by US in 88%, by CT in 63%, and by DC in 89%. In predicting tumor resectability, US was correct in 71% of patients, compared with 42% for CT, 58% for DC, and 25% for angiography. US therefore appears to be the single most useful modality in the evaluation bile duct obstruction.  相似文献   
43.
44.
We prospectively followed 112 hips, undergoing THA with a Spectron EF stem. At mean follow-up of 11.2 years, 21 patients had died. We obtained radiological follow-up in 99% and clinical follow-up in 100% of the surviving 91 hips. Fifty-four percent demonstrated osteolysis in at least one Gruen zone. Twenty-two hips required revision for all causes, with a further five stems radiologically loose. With endpoint being stem revision for aseptic loosening or radiological failure, survivorship at 11 years was 0.783. We believe the addition of a rougher surface finish has contributed to the high levels of osteolysis and stem failure seen with the Spectron EF.  相似文献   
45.
Objective Lateral sinus thrombosis is a potentially devastating but seldom studied complication of cerebellopontine angle (CPA) tumor surgery. Systemic anticoagulation in the early postoperative period has often been avoided due to the potential risks of intracranial hemorrhage.Design Retrospective review.Setting Tertiary referral center.Main Outcome Measures The goal of this study was to identify the frequency, treatment, and outcomes in patients who develop postoperative venous sinus thrombosis following CPA tumor surgery and receive early systemic anticoagulation.Results Of 43 patients with CPA tumors, we report five patients (11.6%) with transverse and/or sigmoid sinus thrombosis following resection of the tumor, four of which were detected on routine early postoperative noncontrast computed tomography (CT) scan. The thrombosis was confirmed in all cases with CT venography or magnetic resonance venography. Affected patients had significantly larger tumors than controls and tended to undergo longer operations. These patients were treated with immediate anticoagulation (intravenous heparin, followed by Coumadin for 6 months) without complication.Conclusion Venous sinus thrombosis is an underrecognized complication of CPA surgery, but it can be diagnosed in the early postoperative period by noncontrast CT imaging. Early postoperative initiation of systemic anticoagulation appears safe and effective to prevent the progression of thrombosis and its consequences.  相似文献   
46.

Background

Management of high-grade T1 (formerly T1G3) bladder cancer continues to be controversial. Should patients with T1G3 bladder cancer have an immediate radical cystectomy or should they receive intravesical bacillus Calmette-Guérin preserving bladder? Gemcitabine and cisplatin (GC) adjuvant chemotherapy may help to strike a balance between intravesical and early cystectomy. For purposes of this study, we continue to refer high-grade T1 lesion as “T1G3.”

Objective

To evaluate the characteristics and the long-term outcome of GC adjuvant chemotherapy in T1G3 bladder cancer after transurethral resection of bladder tumor (TURBT).

Materials and methods

We, retrospectively, reviewed 48 patients who were newly diagnosed with T1G3 bladder cancer between January 2009 and December 2012. A total of 48 patients received 4 cycles of GC adjuvant chemotherapy after TURBT. One month after 4 cycles of GC adjuvant chemotherapy, response was evaluated by re-TURBT. Median follow-up was 59.5 (range: 18–70) months, all patients have been observed for more than 3 years. Salvage cystectomy was recommended for patients with persistent disease and for tumor progression after initial complete response.

Result

Complete response was achieved in 44 (91.7%) patients. Of complete responders, 5 patients experienced recurrence and 5 patients showed progression. The progression rate and disease-specific survival rate were 10.4% and 91.7% at 3 years, respectively. More than 80% of survivors preserved their bladder. Kaplan-Meier curves showed that concomitant carcinoma in situ (CIS) was the only factor that had an influence on progression-free survival (P = 0.022) and disease-specific survival (P = 0.017). Concomitant CIS was the prognostic factor for progression rate and disease-specific survival rate at 3 years (P = 0.008 and P = 0.035).

Conclusion

GC adjuvant chemotherapy is a safe conservative treatment for T1G3 bladder cancer, but effective is really a phase II study. Patients with T1G3 bladder cancer with concomitant CIS should be treated more aggressively because of the high risk of progression.  相似文献   
47.
Additive manufacturing offers exciting new possibilities for improving long‐term metallic implant fixation in bone through enabling open porous structures for bony ingrowth. The aim of this research was to investigate how the technology could also improve initial fixation, a precursor to successful long‐term fixation. A new barbed fixation mechanism, relying on flexible struts was proposed and manufactured as a push‐fit peg. The technology was optimized using a synthetic bone model and compared with conventional press‐fit peg controls tested over a range of interference fits. Optimum designs, achieving maximum pull‐out force, were subsequently tested in a cadaveric femoral condyle model. The barbed fixation surface provided more than double the pull‐out force for less than a third of the insertion force compared to the best performing conventional press‐fit peg (p < 0.001). Indeed, it provided screw‐strength pull out from a push‐fit device (1,124 ± 146 N). This step change in implant fixation potential offers new capabilities for low profile, minimally invasive implant design, while providing new options to simplify surgery, allowing for one‐piece push‐fit components with high levels of initial stability. © 2017 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. on behalf of the Orthopaedic Research Society. J Orthop Res 36:1508–1518, 2018.  相似文献   
48.
49.
安宫牛黄丸中小檗碱的HPLC法测定   总被引:4,自引:0,他引:4  
本文报道用HPLC法测定黄连及含黄连中成药安宫牛黄丸中小檗碱型生物碱。实验结果表明选用硅胶柱为固定相,以醋酸乙酯—甲酸—乙醇(15:3:2)为流动相,能使样品中四种小檗碱型的生物碱获得最佳分离。用此法测得不同厂家生产的安宫牛黄丸中盐酸小檗碱的含量为0.331~0.456%,平均回收率为97.23%,变异系数为1.2%。  相似文献   
50.

Background

Previous research has suggested that a substantial proportion of the population are severely affected by tinnitus, however recent population data are lacking. Furthermore, there is growing evidence that the perception of severity is closely related to personality factors such as neuroticism.

Objective

In a subset (N = 172,621) of a large population sample of > 500,000 adults aged 40 to 69 years, (from the UK Biobank dataset) we calculated the prevalence of tinnitus and that which is perceived as bothersome, and examined the association between tinnitus and a putative predisposing personality factor, neuroticism.

Method

Participants were recruited through National Health Service registers and aimed to be inclusive and as representative of the UK population as possible. The assessment included subjective questions concerning hearing and tinnitus. Neuroticism was self-rated on 13 questions from the Eysenck Personality Inventory. Associations between neuroticism and tinnitus were tested with logistic regression analyses.

Results

Prevalence of tinnitus was significantly higher for males, and increased with age, doubling between the youngest and oldest age groups (males 13% and 26%; females 9% and 19% respectively). Of those with tinnitus, females were more likely to report bothersome tinnitus. Neuroticism was associated with current tinnitus and bothersome tinnitus, with the items: ‘loneliness’, ‘mood swings’, ‘worrier/anxious’ and ‘miserableness’, as the strongest associations of bothersome tinnitus.

Conclusions

Neuroticism was identified as a novel association with tinnitus. Individuals with tinnitus and higher levels of neuroticism are more likely to experience bothersome tinnitus, possibly as a reflection of greater sensitivity to intrusive experiences.  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