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   7253篇
  免费   556篇
  国内免费   18篇
耳鼻咽喉   102篇
儿科学   168篇
妇产科学   114篇
基础医学   839篇
口腔科学   99篇
临床医学   887篇
内科学   1465篇
皮肤病学   146篇
神经病学   483篇
特种医学   203篇
外科学   1105篇
综合类   48篇
一般理论   2篇
预防医学   596篇
眼科学   177篇
药学   757篇
中国医学   53篇
肿瘤学   583篇
  2024年   11篇
  2023年   89篇
  2022年   223篇
  2021年   365篇
  2020年   204篇
  2019年   252篇
  2018年   294篇
  2017年   195篇
  2016年   198篇
  2015年   223篇
  2014年   316篇
  2013年   394篇
  2012年   559篇
  2011年   518篇
  2010年   265篇
  2009年   243篇
  2008年   376篇
  2007年   405篇
  2006年   346篇
  2005年   350篇
  2004年   285篇
  2003年   275篇
  2002年   271篇
  2001年   162篇
  2000年   152篇
  1999年   143篇
  1998年   66篇
  1997年   65篇
  1996年   48篇
  1995年   27篇
  1994年   26篇
  1993年   17篇
  1992年   53篇
  1991年   47篇
  1990年   56篇
  1989年   42篇
  1988年   28篇
  1987年   29篇
  1986年   29篇
  1985年   27篇
  1984年   32篇
  1983年   17篇
  1982年   16篇
  1981年   11篇
  1980年   8篇
  1979年   9篇
  1978年   10篇
  1977年   7篇
  1973年   6篇
  1972年   6篇
排序方式: 共有7827条查询结果,搜索用时 15 毫秒
51.
This case report illustrates atypical magnetic resonance (MR) imaging findings in a liver hemangioma mimicking a malignant lesion—lower signal intensity than cerebrospinal fluid on T2-weighted spin-echo images and lack of early enhancement on dynamic contrast material—enhanced gradient-echo images. Pathologic analysis demonstrated nearly total replacement of the vascular cavities by dense fibrous tissue. In this rare, sclerosed form, this lesion could not be defined as a hemangioma with MR imaging.  相似文献   
52.
Antigen-presenting dendritic cells are present in atherosclerotic lesions in human arterial intima, but have not been investigated in atherosclerotic and hyperplastic stenotic lesions that affect vein grafts used as arterial conduits. This study was undertaken to examine whether dendritic cells are present in aortocoronary artery saphenous vein bypass grafts affected by high-grade atheromatous stenosis. Stenotic saphenous vein coronary artery bypass grafts (angiographic luminal stenosis > 75%) were harvested from 10 patients (nine male, one female), aged 4271 years (mean 56.5) at re-do operation. The mean time interval from bypass surgery to the excision of stenotic grafts was 11.5 years (range 2-21). The specimens were fixed in 10% buffered formalin, embedded in paraffin blocks and the sections stained with antibodies to S-100 (to identify dendritic cells), CD3 (T cells), CD68 (macrophages), von Willebrand factor (endothelial cells) and alpha-smooth muscle actin (smooth muscle cells) using avidin-biotin complex immunoperoxidase technique. Normal veins were obtained during saphenous vein femoro-popliteal grafting. The stenotic venous grafts showed histological features typical of extensive arterialization, intimal hyperplasia, atherosclerotic plaque-like lesions, calcification and thrombosis. In areas of intimal hyperplasia, S-10O-positive cells were distributed irregularly among smooth muscle cells. S-100-positive dendritic cells were seen most frequently within atherosclerotic plaque-like lesions where they co-localized with CD3+ cells and CD68+ cells. S-100-positive dendritic cells were also seen accumulating within calcific foci. No S-100-positve cells were found in normal, ungrafted saphenous veins. We conclude that dendritic cells are present in aortocoronary saphenous vein bypass grafts affected by high grade stenosis. Dendritic cells are probably involved in immune mechanisms of atherogenesis through their interactions with T cells and macrophages. The accumulation of dendritic cells within calcific foci suggests their contribution to the calcification of stenotic venous grafts.  相似文献   
53.
BACKGROUND: The combination of gamma-probe radiolocalization and blue-dye mapping of sentinel lymph nodes (SLNs) has been advocated as the most accurate method for staging the clinically negative axilla in breast cancer patients, but the technical aspects of these procedures are not fully characterized in the literature. In this study, we compared the success of SLN localization in 134 consecutive breast cancer patients using blue dye plus two different preparations of radiocolloid. STUDY DESIGN: A retrospective analysis of a prospectively maintained data base was performed to assess SLN localization in two cohorts of patients. Unfiltered technetium-99m (Tc-99m) sulfur colloid (in 77 patients; group I) was compared with filtered Tc-99m sulfur colloid (in 57 patients; group II). All patients had a peritumoral injection of blue dye and isotope, followed immediately by lymphoscintigraphy to confirm radioactivity at the injection site and to image the SLN. Statistical analysis was performed using the Pearson chi-square test. RESULTS: Unfiltered Tc-99m sulfur colloid was superior to the filtered radiocolloid in localizing the SLN (88% versus 73%; p = 0.03). SLN imaging by lymphoscintigraphy was also more successful in the unfiltered group. Using the combination of blue dye and radiolocalization, SLNs were identified in 94% of patients. CONCLUSIONS: For optimal localization of the SLN in breast cancer patients, surgeons should use the combined technique of blue-dye mapping and gamma-probe localization using unfiltered Tc-99m sulfur colloid.  相似文献   
54.
STUDY AIM: The aim of this study was to report the immediate results of a series of 65 hepatic resections for hepatolithiasis performed in Vietnam. PATIENTS AND METHOD: From 1986 to 1998, 44 men and 21 women (mean age: 40 years) underwent hepatic resection for hepatolithiasis. Fourty patients had previously undergone one or several operations for hepatolithiasis. The procedure was performed on emergency in 25 patients. Indications for hepatic resection were: angiocholitis and liver abscess in 22 cases, stones closely inserted in the biliary duct in 20 cases, hemobilia in 12 cases, stones located above a biliary stricture in 8 cases and stones associated with a postoperative biliary fistula in 3 cases. Liver resections (minor in 61 patients, including 55 left lobectomies, and major in 4 patients) were performed through transhepatic approach according to the Ton That Tung technique and followed by an external biliary drainage with a Kehr tube. RESULTS: There were 6 postoperative deaths (9%), 3 due to septic shock, 2 to cachexia, and 1 to liver failure. The 15 patients with complications recovered with conservative therapy. Bile infection was present in 93%, mostly with Escherichia coli and Enterobacter. Pigmented stones were usually found. CONCLUSION: Vietnam is a country with high incidence of hepatolithlasis. Hepatic resection is an adequate treatment for localized intrahepatic bile duct stones when the involved segment including biliary strictures and calculi can be completely removed. The procedure may be performed on emergency for liver abscess, or hemobilia.  相似文献   
55.
56.
BackgroundDespite the effectiveness of Roux-en-Y gastric bypass (RYGB) in promoting excess weight loss, 40% of the patients regain weight. Endoscopic gastric plication (EGP) using the StomaphyX device can serve as a less-invasive procedure for promoting the loss of regained weight. Our objective was to evaluate the effectiveness of the StomaphyX device in sustaining ongoing weight loss in patients who have regained weight after RYGB at the Division of Minimally Invasive and Bariatric Surgery, Howard University Hospital.MethodsWe performed a retrospective chart review of patients undergoing EGP using the StomaphyX device from April 2008 to May 2010. The patient demographics and clinical information were assessed. Effective weight loss and the proportion of weight lost after EGP relative to the weight regained after achieving the lowest weight following RYGB was calculated.ResultsA total of 27 patients underwent EGP using the StomaphyX device; of these, most were women (n = 25, 93%) and black (n = 14, 52%), followed by white (n = 11, 42%), and Hispanic (n = 1, 4%). The median interval between RYGB and EGP was 6 years, with an interquartile range of 5–8 years. After the EGP procedure, the median effective weight loss was 37% (interquartile range 24–61%). Of the 27 patients, 18 had ≥6 months of follow-up after EGP. Eleven patients had achieved their lowest weight at 1–3 months, 7 at 6 months, and 3 at 12 months. Of the 18 patients, 13 (72%) experienced an increase in weight after achieving their lowest weight after EGP.ConclusionThe use of the StomaphyX device achieved the maximum effective weight loss during the 1–6-month period after EGP.  相似文献   
57.
Study Type – Therapy (case series) Level of Evidence 4 What's known on the subject? and What does the study add? To date, there is controversy about the impact of histological subtype of bladder cancer (nonbilharzial squanous cell carcinoma vs. urothelial carcinoma) on cancer control outcomes. Our study shows that the histological subtype may have an impact on the stage of bladder cancer at presentation. However, after adjusting to stage, the histological subtype has no impact on cancer control outcomes.

OBJECTIVES

  • ? To test the effect of histological subtype (NBSCC vs UC) on cancer‐specific mortality (CSM), after adjusting for other‐cause mortality (OCM).
  • ? In Western countries, non‐bilharzial squamous cell carcinoma (NBSCC) is the second most common histological subtype in bladder cancer (BCa) after urothelial carcinoma (UC).

PATIENTS AND METHODS

  • ? We identified 12 311 patients who were treated with radical cystectomy (RC) between 1988 and 2006, within 17 Surveillance, Epidemiology and End Results (SEER) registries.
  • ? Univariable and multivariable competing‐risks analyses tested the relationship between histological subtype and CSM, after accounting for OCM.
  • ? Covariates consisted of age, sex, year of surgery, race, pathological T and N stages, as well as tumour grade.

RESULTS

  • ? Histological subtype was NBSCC in 614 (5%) patients vs UC in 11 697 (95%) patients.
  • ? At RC, the rate of non‐organ confined (NOC) BCa was higher in NBSCC patients than in their UC counterparts (71.7% vs 52.2%; P < 0.001).
  • ? After adjustment for OCM, The 5‐year cumulative CSM rates were 25.0% vs 19.8% (P= 0.2) for patients with NBSCC vs UC organ confined (OC) BCa, respectively. The same rates were 46.3% vs 49.3% in patients with NOC BCa (P= 0.1).
  • ? In multivariable competing‐risks analyses, histological subtype (NBSCC vs UC) failed to achieve independent predictor status of CSM in patients with OC (hazard ratio, 1.2; P= 0.06) or NOC BCa (hazard ratio, 1.1; P= 0.1).

CONCLUSIONS

  • ? At RC, the rate of NOC BCa is higher in NBSCC patients than in their UC counterparts.
  • ? Despite a more advanced stage at surgery, NBSCC histological subtype is not associated with a less favourable CSM than UC histological subtype, after accounting for OCM and the extent of the disease (OC vs NOC).
  相似文献   
58.

Background

Migration is the most common complication of the fully covered metallic self-expanding esophageal stent (SEMS). This study aimed to determine the potential preventive effect of proximal fixation on the mucosa by clips for patients treated with fully covered SEMS.

Methods

In this study, 44 patients (25 males, 57%) were treated with fully covered SEMS including 22 patients with esophageal stricture (4 malignant obstructions, 6 anastomotic strictures, and 12 peptic strictures) and 22 patients with fistulas or perforations (10 anastomotic leaks, 4 perforations, and 8 postbariatric surgery fistulas). The Hanarostent (n?=?25), Bonastent (n?=?5), Niti-S (n?=?12), and HV-stent (n?=?2) with diameters of 18 to 22?mm and lengths of 80 to 170?mm were used. Two to four clips (mean, 2.35?±?0.75 clips) were used consecutively in 23 patients to fix the upper flared end of the stent with the esophageal mucosal layer. Stent migration and its consequences were collected in the follow-up assessment with statistical analysis to compare the patients with and without clip placement.

Results

No complication with clip placement was observed, and the retrieval of the stent was not unsettled by the persistence of at least one clip (12 cases). Stent migration was noted in 15 patients (34%) but in only in 3 of the 23 patients with clips (13%). The number of patients treated to prevent one stent migration was 2.23. The predictive positive value of nonmigration after placement of the clip was 87%. In the multivariate analysis, the fixation with clips was the unique independent factor for the prevention of stent migration (odds ratio, 2.3; 95% confidence interval, 0.10?C0.01; p?=?0.03).

Conclusions

Anchoring of the upper flare of the fully covered SEMS with the endoscopic clip is feasible and significantly reduces stent migration.  相似文献   
59.
Background: The optimal treatment of ductal carcinoma in situ (DCIS) is one of the most controversial issues in the management of breast cancer. Identification of factors that affect the risk of local recurrence is very important as the incidence of DCIS increases and the use of breast conservation becomes more widespread. Because the extent of resection may affect the relapse rate, we hypothesized that larger volumes of resection (VR) may account for the lower local recurrence rates we have previously found in elderly patients. Methods: Between 1978 and 1990, 173 cases of histologically confirmed DCIS were treated at MSKCC with breast conservation therapy. Of these, complete VR data were available for 126 cases. The VRs thus obtained were divided into two groups, <60 cm3 and 60 cm3, and were evaluated for correlating factors. The patients were divided into three groups by age at diagnosis: younger than 40 years, 40 to 69 years, and 70 years or older. Results: The eldest group had a significantly greater proportion of large VRs (30%) as compared to the middle group (11%) and the youngest group (9%) (P=.03, x2). Although not statistically significant, the large VR group had a lower 6-year actuarial local recurrence rate (5.6%) than did the small VR group (21.3%) (P=.16, log-rank test). This trend was observed even though adjuvant radiotherapy was used less often in patients who had large VRs. Conclusion: Breast conservation surgery for DCIS in elderly patients is more likely to employ a large VR. This may explain, at least in part, the observation that elderly patients have a lower local recurrence rate.Presented at the 50th Annual Cancer Symposium of The Society of Surgical Oncology, Chicago, Illinois, March 20–23, 1997.  相似文献   
60.

Purpose

Local tumor ablation (LTA) and partial nephrectomy (PN) represent treatment alternatives for patients diagnosed with small renal mass and both may result in renal function detriments. The aim of the study was to compare renal function detriments after LTA or PN.

Methods

A Surveillance epidemiology and End Results-Medicare-linked retrospective cohort of 2850 T1 kidney cancer patients who underwent LTA or PN was abstracted. Short-term outcomes consisted of 30-day acute kidney injury (AKI) and 30-day dialysis rates. Long-term outcomes consisted of episodes of AKI, mild and moderate–severe chronic kidney disease (CKD), end-stage renal disease, hemodialysis and anemia in CKD. Analyses consisted of propensity score matching, logistic and Cox regression.

Results

After propensity score matching, 1122 patients remained. The 30-day incidence of AKI was 4.6 % after LTA and 9.4 % after PN. In multivariable analyses (MVAs), LTA was associated with a lower AKI rate (OR 0.42; p = 0.001). The 30-day incidence of any dialysis was <2 % after either LTA or PN. In MVA, LTA was not associated with a lower rate of any dialysis (OR 0.43; p = 0.2). At long-term assessment, both the unadjusted and adjusted rates of all six examined end points were not different between LTA and PN (all p > 0.5).

Conclusions

LTA offers short-term protective effect from AKI. The short-term rates of any dialysis treatment are similar after either LTA or PN. At long-term assessment, LTA and PN renal function detriment rates are not different. Concern for long-term functional outcomes should not be a barrier for PN.
  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