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   4663篇
  免费   319篇
  国内免费   59篇
耳鼻咽喉   100篇
儿科学   93篇
妇产科学   53篇
基础医学   698篇
口腔科学   97篇
临床医学   352篇
内科学   949篇
皮肤病学   168篇
神经病学   331篇
特种医学   435篇
外科学   704篇
综合类   30篇
预防医学   202篇
眼科学   52篇
药学   401篇
中国医学   51篇
肿瘤学   325篇
  2023年   22篇
  2022年   70篇
  2021年   133篇
  2020年   75篇
  2019年   89篇
  2018年   148篇
  2017年   92篇
  2016年   164篇
  2015年   187篇
  2014年   291篇
  2013年   284篇
  2012年   377篇
  2011年   366篇
  2010年   202篇
  2009年   207篇
  2008年   243篇
  2007年   238篇
  2006年   248篇
  2005年   246篇
  2004年   201篇
  2003年   172篇
  2002年   169篇
  2001年   88篇
  2000年   77篇
  1999年   80篇
  1998年   31篇
  1997年   32篇
  1996年   45篇
  1995年   27篇
  1994年   27篇
  1993年   29篇
  1992年   34篇
  1991年   39篇
  1990年   28篇
  1989年   27篇
  1988年   34篇
  1987年   22篇
  1986年   30篇
  1985年   20篇
  1984年   19篇
  1983年   19篇
  1982年   16篇
  1981年   7篇
  1980年   9篇
  1979年   15篇
  1978年   6篇
  1977年   9篇
  1976年   9篇
  1975年   12篇
  1974年   8篇
排序方式: 共有5041条查询结果,搜索用时 15 毫秒
41.
A mentally retarded female child with multiple congenital abnormalities had an abnormal X chromosome and a Y chromosome; the karyotype was interpreted as 46,dup(X)(p21 leads to pter)Y. Prenatal chromosome studies in a later pregnancy indicated the same chromosomal abnormality in the fetus. The fetus and proband had normal female genitalia and ovarian tissue. H--Y antigen was virtually absent in both sibs, a finding consistent with the view that testis-determining genes of the Y chromosome may be suppressed by regulatory elements of the X. The abnormal X chromosome was present in the mother, the maternal grandmother, and a female sib: all were phenotypically normal and showed the karyotype 46,Xdup(X)(p21 leads to pter) with non-random inactivation of the abnormal X. Anomalous segregation of the Xga allele suggests that the Xg locus was involved in the inactivation process or that crossing-over at meiosis occurred.  相似文献   
42.
Focal gastric mucosal blood flow in aspirin-induced ulceration.   总被引:3,自引:1,他引:2       下载免费PDF全文
T J Gana  R Huhlewych    J Koo 《Annals of surgery》1987,205(4):399-403
Focal gastric mucosal blood flow was studied during aspirin injury by hydrogen gas clearance in a chambered segment model of canine gastric corpus. Measurements were made simultaneously every 15 minutes at ulcerated and nonulcerated areas 1.5 hours before, during (20 mM of aspirin in 150 mM of HCl for 1 hour), and 2 hours after exposure of the mucosa to topical aspirin. There was a highly significant decrease (p less than 0.001) in flow at the ulcerated areas 30 minutes after exposure to aspirin, coinciding with the appearance of focal mucosal pallor followed by subsequent hemorrhagic foci and ulceration. This was not followed by recovery to basal flow values. Blood flow to the non-ulcerated areas was significantly but less severely reduced than in the ulcerated areas (p less than 0.05) 90 minutes after exposure to aspirin. This was followed by recovery to basal levels. It is proposed that aspirin induces reduction of focal mucosal blood flow of varying degrees and that mucosal areas with flow reduced to below a "critical value" develop gross damage.  相似文献   
43.
Globally, many countries are facing an increasing burden of chronic disease due to ageing populations, of which cardiovascular disease forms a large proportion. Excess dietary sodium contributes to cardiovascular disease risk and requires intervention at a population level. This study aimed to quantify the impact of several salt reduction initiatives on population health over a 30-year horizon using GeoDEMOS, a population model from Singapore. Four interventions were modelled in four demographic groups in 2020 for a total of 16 intervention scenarios. The effect of 0.5, 2.0, and 4.0 g/day reductions in daily salt consumption, along with adherence to the World Health Organization guidelines of a maximum of 5.0 g of salt each day, was modelled in the entire population, including the overweight and obese, the elderly, and diabetics. In each scenario, the number of averted incident cases of acute myocardial infarction and stroke, along with the disability-adjusted life years up to 2050, was monitored. We found 4.0 g/day reductions in salt consumption were the most effective when implemented across the entire population, resulting in 24,000 averted incident cases of cardiovascular disease and 215,000 disability-adjusted life years over 30 years. This is a large figure when compared with the 29,200 projected annual incident cases of cardiovascular disease in 2050. When targeted at specific high-risk demographic groups, the largest effects were observed in the overweight and obese, with the same intervention yielding 10,500 averted incident cases of cardiovascular disease and 91,500 disability-adjusted life years. Quantifying the benefits of salt reduction initiatives revealed a significant impact when administered across the entire population or the overweight and obese. Health promotion efforts directed toward sustainably reducing salt consumption will help to lower the chronic disease burden on the healthcare system in years to come.  相似文献   
44.
One reported complication of the arthroscopic modified Broström operation is pain caused by the suture anchoring knot. We hypothesized that a knotless technique could reduce such pain. Therefore, in this study we evaluated the clinical and radiological outcomes after knotless all-inside arthroscopic modified Broström operation for lateral ankle instability. From July 2017 to November 2017, 28 patients were treated. Clinical and radiological features were evaluated preoperatively and 3, 6, and 12 months postoperatively using the American Orthopaedic Foot & Ankle Society ankle-hindfoot scale score, visual analogue scale score for pain, anterior talar drawer test, and talar tilt angle. The mean age of the 28 patients (14 men, 14 women) was 41.71 ± 17.19 years. Three (10.7%) complications, but no knot-associated pain, occurred. The clinical and radiological outcomes were significantly improved 12 months postoperatively compared with preoperative outcomes (all p < .05). Knotless all-inside arthroscopic modified Broström operation for lateral ankle instability avoided knot-associated pain and improved not only patient satisfaction but also clinical and radiological outcomes.  相似文献   
45.
The treatment of syndesmotic injuries with ankle fractures is controversial. The purpose of this study was to compare the biomechanical properties of open anterior syndesmotic repair with those of screw fixation. Ten matched pairs of human cadaver specimens were subjected to open syndesmotic repair or screw fixation. Each specimen underwent initial intact physiologic loading, consisting of 10 cycles of external torsional loading with a peak torque of 7.5 Nm at 0.05 Hz. Injuries of the anterior inferior tibiofibular ligament, tibiofibular interosseous membrane, and deltoid ligament were applied to each specimen. Postfixation cyclic loading consisted of 50 cycles of combined axial and external rotation loading with peak torques of 750 N and 7.5 Nm at a rate of 0.05 Hz. After postfixation loading, each specimen underwent failure loading by external rotation at 0.25 degrees/second. Failure torque and failure angle were measured. The paired t test and Wilcoxon signed-rank test were used to analyze the data. Mean failure torques were 95.63 Nm in the open anterior syndesmotic repair augmented with suture-tape group and 108.61 Nm in the screw group. Mean failure angles were 34.93 degrees in the open anterior syndesmotic repair augmented with suture-tape group and 43.55 degrees in the screw group. These data were not statistically significantly different between the groups (p= .7682 and .4133, respectively). Open anterior syndesmotic repair augmented with suture tape for ankle syndesmotic injury provides similar torsional strength to that of screw fixation. Therefore, this technique can be considered as an alternative treatment option for syndesmosis injury.  相似文献   
46.
BackgroundHallux valgus is bilateral in up to 84 % of cases. In the setting of simultaneous bilateral correction, we aim to evaluate if minimally invasive percutaneous surgery (MIS) provides any advantage compared to conventional open surgery.Methods52 feet (26 patients) undergoing simultaneous bilateral MIS surgery were matched by severity of deformity to 52 feet (26 patients) undergoing simultaneous conventional open surgery. Patients were followed for a minimum of six months. Pre- and post-operative radiographs and clinical records were reviewed.ResultsThere were no significant differences in pre-operative function or pain between both groups. Post-operatively, the mean hallux valgus angle (HVA) was significantly lower in the MIS group. (HVA MIS – 8.6; Open – 11.8, P = 0.013). There were no significant differences in post-operative outcome and patient satisfaction between both groups.ConclusionThis study demonstrates that simultaneous bilateral MIS hallux valgus surgery can be considered for patients with bilateral symptomatic hallux valgus.  相似文献   
47.
BackgroundBone tumors can cause severe pain and poor quality of life due to recurrence and non-achievement of complete remission after surgery, chemotherapy, or radiotherapy. Radiofrequency ablation (RFA) can be considered for minimally invasive treatment of bone tumors that are difficult to radically excise. In this study, RFA was performed for bone tumors that were difficult to radically excise and did not respond to surgery, chemotherapy, or radiotherapy due to their large sizes and/or locations. The purpose of this study was to retrospectively analyze the clinical characteristics and survival rates of bone tumors after RFA and provide one more treatment option for the future.MethodsThere were 43 patients with bone tumors who underwent percutaneous RFA at our hospital from April 2007 to October 2017. The median age of the patients was 59 years (range, 31–75 years), and the median follow-up duration was 67.2 months (range, 10.2–130.5 months). Of the 43 patients, 26 were male and 17 were female. Thirty-four cases were metastatic bone tumors, 5 were chordomas, 3 were osteosarcomas, and 1 was a giant cell tumor. Pain and functional ability of the patients were evaluated using a visual analog scale (VAS) and the Musculoskeletal Tumor Society (MSTS) functional scoring system, respectively. Scores were recorded preoperatively, 1 week postoperatively, and 4 weeks postoperatively. The 1-year, 2-year, and 5-year survival rates were evaluated using the Kaplan-Meier method.ResultsThe mean VAS score was 8.21 preoperatively. The mean VAS score at 1 week, 4 weeks, 12 weeks, and 24 weeks postoperatively were 3.91, 3.67, 3.31, and 3.12, respectively. The mean preoperative MSTS score was 64.0% (range, 32%–87%). The mean postoperative MSTS score was 71.0% (range, 40%–90%). The 1-year, 2-year, and 5-year survival rates were 95.3%, 69.8%, and 30.2%, respectively.ConclusionsAs per our study findings, RFA was effective in reducing pain and improving functional ability of patients with bone tumors that were difficult to radically excise.  相似文献   
48.
同种异体黑素细胞移植治疗白癜风   总被引:2,自引:2,他引:0  
卢涛  高天文  刘玉峰  李春英  孙林潮 《医学争鸣》2001,22(12):1147-1147
0 引言 白癜风患者免疫紊乱 ,黑素细胞 (melanocyte,MC)异体移植有可能不被排斥 ,治疗如成功将有很大临床前景 [1 ] .探索同种异体黑素细胞移植后的效果很有意义 .1 病例报告 女 ,2 7岁 ,确诊白癜风 (稳定期 ) ,患者皮肤自幼出现色素脱失斑 ,逐渐增多扩大 . 1996年外用“敏白灵”,前2 mo有效 . 1999- 0 7外用补骨酯酊 ,日服 5 g· L- 1 硫酸铜 10m L和中药 1剂 ,转移因子 4m L ,sc,1· 2 d- 1 .皮损缩小 ,4mo后稳定 .用健康男青年环切的包皮培养 MC,第 4代大约80 %融合时 ,用 2 .5 g· L- 1 胰酶消化 5 min,加入含 2 0 0 g·L- 1小…  相似文献   
49.
The effect of the root ofCoptis japonica (COPT), both the dichloromethane soluble (CH2Cl2) and insoluble (H2O) fractions, on catecholamine contents and tyrosine hydroxylase (TH) activity in PC12 cells was investigated. CH2Cl2 and H2O fractions showed 21 and 53% inhibitions on dopamine content, respectively, at a concentration of 40 μg/ml in medium: the H2O fraction provided a greater inhibitory effect. The TH activity was reduced by the treatment of COPT (H2O fraction). These results suggest that COPT has an inhibitory effect on the catecholamine biosynthesis by the reduction of TH activity in PC12 cells.  相似文献   
50.
Koo KH  Ahn IO  Kim R  Song HR  Jeong ST  Na JB  Kim YS  Cho SH 《Radiology》1999,211(3):715-722
PURPOSE: To determine the accuracy of magnetic resonance (MR) cholangiography for demonstration of the biliary tract and detection of biliary complications in patients who have undergone orthotopic liver transplantation. MATERIALS AND METHODS: Breath-hold half-Fourier rapid acquisition with relaxation enhancement MR cholangiography was performed in 25 patients who had undergone orthotopic liver transplantation. MR cholangiograms were prospectively and independently interpreted by two radiologists for depiction of the biliary tract and ductal anastomosis and for complications (eg, biliary dilatation, stricture, stones). MR cholangiographic findings were correlated with findings from direct cholangiography (n = 24) and surgery (n = 1). RESULTS: MR cholangiography completely demonstrated first-order intrahepatic bile ducts in 23 (92%) patients, the donor extrahepatic bile duct in 25 (100%), the recipient extrahepatic bile duct in 17 of 18 (94%), and the anastomosis in 24 (96%). The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of MR cholangiography for detection of biliary dilatation and stricture were each 100%. Complete interobserver agreement occurred in the detection of biliary dilatation and stricture. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of MR cholangiography for detection of stones were 100% for one radiologist and 86%, 100%, 96%, 100%, and 95%, respectively, for the other. Both radiologists agreed on the diagnosis of bile duct stones in six of seven cases (kappa = 0.90). CONCLUSION: MR cholangiography enables accurate depiction of the biliary tract and detection of biliary complications in patients with an orthotopic liver transplant.  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