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   5706篇
  免费   299篇
  国内免费   42篇
耳鼻咽喉   45篇
儿科学   76篇
妇产科学   67篇
基础医学   725篇
口腔科学   117篇
临床医学   445篇
内科学   1406篇
皮肤病学   98篇
神经病学   529篇
特种医学   159篇
外科学   1027篇
综合类   59篇
一般理论   4篇
预防医学   340篇
眼科学   85篇
药学   401篇
中国医学   14篇
肿瘤学   450篇
  2023年   45篇
  2022年   62篇
  2021年   138篇
  2020年   63篇
  2019年   104篇
  2018年   122篇
  2017年   97篇
  2016年   119篇
  2015年   142篇
  2014年   165篇
  2013年   203篇
  2012年   325篇
  2011年   302篇
  2010年   181篇
  2009年   149篇
  2008年   265篇
  2007年   266篇
  2006年   278篇
  2005年   245篇
  2004年   234篇
  2003年   250篇
  2002年   257篇
  2001年   220篇
  2000年   206篇
  1999年   164篇
  1998年   57篇
  1997年   43篇
  1996年   44篇
  1995年   31篇
  1994年   27篇
  1993年   35篇
  1992年   108篇
  1991年   117篇
  1990年   89篇
  1989年   117篇
  1988年   88篇
  1987年   90篇
  1986年   57篇
  1985年   52篇
  1984年   53篇
  1983年   49篇
  1979年   32篇
  1978年   25篇
  1977年   24篇
  1976年   23篇
  1973年   29篇
  1972年   29篇
  1971年   28篇
  1970年   21篇
  1969年   21篇
排序方式: 共有6047条查询结果,搜索用时 78 毫秒
1.
2.
3.
Background

There is an increasing incidence of elderly patients requiring emergency laparotomy. Our study compares the outcomes of elderly patients undergoing emergency laparotomy against the outcomes of non-elderly patients.

Methodology

Patients who underwent emergency laparotomy between 2015 and 2017 from the National University Hospital, Singapore, were included. Apart from demographic data, indication of surgery and surgical procedure performed were collected. Prospectively collected nutritional scores were evaluated. Outcome measures included duration of surgery, length of ICU and total hospital stay, post-operative complications, and mortality indices. We performed multivariate Cox regression analysis to determine the contribution of various risk factors towards overall survival following emergency laparotomy.

Results

A total of 170 emergency laparotomies were performed. Compared to non-elderly patients, elderly patients had a significantly longer mean stay in hospital (31.5 vs. 18.6 days, p = 0.006) and mean stay in ICU (13.1 vs. 5.3 days, p = 0.003). More elderly patients suffered from post-laparotomy complications compared with non-elderly patients (65.8% vs. 37.4%, p < 0.001). 30-day mortality (31.5% vs. 8.8%, p = 0.019) and 1-year mortality (27.9% vs. 14.3%, p = 0.023) were higher in elderly patients compared with non-elderly patients. Interestingly, there was no statistically significant difference between elderly and non-elderly groups in both the global 3-MinNS as well as the global SGA nutritional scores. ASA status (HR 2.61, 95% CI 1.05–6.45, p = 0.038) was an independent risk factor for decreased survival following emergency laparotomy. Notably, while age ≥ 65 demonstrated a significant correlation with survival on univariate analysis (HR 1.03 (1.01–1.05), p = 0.003), this effect was lost following multivariate regression (HR 1.01 (0.453–2.23), p = 0.989).

Conclusion

Elderly patients suffer worse morbidity and mortality following emergency laparotomy. This is likely contributed by comorbidities resulting in higher ASA status.

  相似文献   
4.
Background During anterior cruciate ligament (ACL) reconstruction, placement of the reconstructed ligament affects the clinical results. To accomplish accurate and reproducible placement of the tibial bone tunnel, we employed a fluoroscopic navigation system for endoscopic ACL reconstruction. In this study, preciseness of the tibial tunnel placement was evaluated, and the advantages and disadvantages of this navigation system for endoscopic ACL reconstruction are discussed. Methods Altogether, 16 knees of 16 patients who had undergone ACL reconstruction using this system (navi group) were evaluated regarding the positioning of the tibial tunnel against Blumensaat's line using X-p and the route of the graft by magnetic resonance imaging (MRI). Another 16 knees of 16 patients who underwent endoscopic ACL reconstruction without the navigation system were the controls (control group). Results At the 1-year follow-up, maximally extended lateral knee X-p revealed that the anterior edge of the tibial tunnel and Blumensaat's line were almost aligned and that roof impingement was avoided; the T2-weighted MR images showed that the graft was placed close to and parallel to the intercondylar roof in all the knees of the navi group. The ratio of the distance between Blumensaat's line and the anterior edge of the tibial tunnel at the level of the tibial plateau to the anteroposterior width in fully extended true lateral radiographs was 2.7% ± 3.4% in the navi group and 8.4% ± 7.4% in the control group. Conclusions The computer-assisted fluoroscopic navigation system improves accuracy and decreases dispersion of the tibial tunnel placement against Blumensaat's line in single-bundle ACL reconstruction. This innovative device renders the reconstruction procedure more reliable, eliminating the problem of skeletal variation among patients. However, the function of this navigation system for femoral tunnel placement is insufficient at present. Further refinement of the system is necessary, and the method of application requires improvement.  相似文献   
5.
We report the case of a 4-year-old girl who had quadricuspid aortic valve regurgitation with tetralogy of Fallot and pulmonary atresia. This combination is very uncommon. Aortic valve replacement was performed successfully due to aortic regurgitation which had progressed one year after the total repair. The dilated aortic annulus plus quadricuspid aortic valve may result in progressive aortic regurgitation for a short period.  相似文献   
6.
The presence of cytochrome P-45011 beta in rat brain was studied by immunohistochemistry using polyclonal rabbit antibodies raised against purified bovine adrenocortical P-45011 beta, which is involved in the steroid 11 beta-hydroxylation and glucocorticoid formation. The results showed that cytochrome P-45011 beta immunoreactivity is selectively localized to the tracts of myelinated fibers throughout the brain. The specificity of immunohistochemical stainings with P-45011 beta antibodies was established by control tests including nonimmune rabbit immunoglobulin Gs and P-45011 beta antibodies absorbed with purified antigen. Western immunoblots of homogenates from different brain areas with P-45011 beta antibodies, together with biochemical enzymatic assays for cytochrome P-45011 beta monooxygenase activity in these homogenates, confirmed the selective localization of this enzyme observed with immunohistochemistry. Cytochrome P-45011 beta and 11 beta-hydroxylase activity were detected in a homogenate from the cortical white matter (brain area rich in myelinated fibers) as in that from the rat adrenal, but were not detectable in a homogenate from the cerebral cortex (brain area poor in myelinated fibers). Furthermore, quantitation of the P-45011 beta bands on the immunoblots by the areal density revealed that the cortical white matter contains approximately 1.4 pmol of cytochrome P-45011 beta/mg of tissue protein, the value of which was about one sixth of the corresponding value estimated in the rat adrenal. This relatively high content of cytochrome P-45011 beta was also reflected in a relatively high level of 11 beta-hydroxylase activity measured in a homogenate of this brain area by biochemical enzymatic assays using [4-14C]-11-deoxycorticosterone.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
7.
8.
Renal cell carcinoma (RCC) causes many kinds of symptoms such as hypercalcemia, hypertension, polycythemia and fever. Here we describe a rare case of RCC presenting with a persistent cough. After radical nephrectomy, the obstinate cough disappeared. When the tumor recurred locally, the cough also recurred. Furthermore, the cough disappeared completely again after the removal of the recurrent tumor. Although all the clinical findings suggested that the RCC caused the cough, we could not identify a specific humoral substance responsible for the cough.  相似文献   
9.
This paper presents a statistical model constructed using logisticregression to identify those at high-risk of repeating parasuicide. Thesubjects in the study are Cork city residents who exhibited parasuicidalbehaviour between 1 January and 30 June 1995. Repetition of the behaviourwithin six months of the index episode distinguishes repeaters fromnon-repeaters. The model was designed so that it could be used bynon-clinicians and hence does not require information relating topsychiatric diagnosis or use of psychiatric services. The proportion ofsubjects correctly classified remained stable across a range of cut-pointprobabilities (mean = 86%, range: 83.9–87.5%). Using acut-point of 0.2, 96% of repeaters and 81% of non-repeaters were correctly classified. Using 0.45 led to the correct identification of81% of repeaters and 90% of non-repeaters. If these highlevels of sensitivity and specificity are maintained in validation tests onfuture cohorts in Cork city then the model could form the basis of anintervention programme designed to prevent the repetition of parasuicide.  相似文献   
10.
The midportion of the anterior cruciate ligament (ACL) of rabbits was partially transected, and the effect of hyaluronan (HA) on its healing was determined. A 1% solution of HA (HA group) or physiological phosphate-buffered saline (control group) was administered intraarticularly, at 0.1 ml/kg body weight, once a week from 1 week after the operation. Two, 4, and 6 weeks after the initiation of HA administration, the ACLs were examined grossly, histologically and immunohistochemically. At 2 weeks, the lacerated portions were completely covered with scar-like tissue in both groups. These tissue areas were smaller in the HA group than in the control group. Histologically in the HA group, the regularity of collagen fibers (indicating the maturity of regenerated collagen fibers) had increased compared to findings in the control group, and the number of fibroblastic cells decreased gradually at a significantly faster rate. The number of inflammatory cells and blood vessels decreased gradually in both groups, with these values being lower in the HA group at each time point but not significantly so. Immunohistochemical examination of the repaired tissue revealed strong staining with anti-chondroitin sulfate proteoglycan antibody in the HA group 2 weeks after the first HA administration. The staining gradually became reduced, with the rate of reduction being faster in the HA group than in the control group. The stimulation of chondroitin sulfate proteoglycan production and the faster reduction of it in the HA group suggests that HA facilitated tissue repair and inhibited the formation of scar tissue.  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