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   11008篇
  免费   755篇
  国内免费   80篇
耳鼻咽喉   93篇
儿科学   159篇
妇产科学   143篇
基础医学   1757篇
口腔科学   213篇
临床医学   1018篇
内科学   2399篇
皮肤病学   171篇
神经病学   1082篇
特种医学   443篇
外科学   1664篇
综合类   131篇
现状与发展   1篇
一般理论   5篇
预防医学   638篇
眼科学   316篇
药学   780篇
中国医学   25篇
肿瘤学   805篇
  2023年   85篇
  2022年   277篇
  2021年   453篇
  2020年   220篇
  2019年   249篇
  2018年   348篇
  2017年   224篇
  2016年   274篇
  2015年   350篇
  2014年   435篇
  2013年   540篇
  2012年   807篇
  2011年   903篇
  2010年   473篇
  2009年   446篇
  2008年   705篇
  2007年   695篇
  2006年   643篇
  2005年   650篇
  2004年   561篇
  2003年   536篇
  2002年   495篇
  2001年   75篇
  2000年   56篇
  1999年   81篇
  1998年   96篇
  1997年   85篇
  1996年   59篇
  1995年   53篇
  1994年   60篇
  1993年   49篇
  1992年   32篇
  1991年   34篇
  1990年   31篇
  1989年   27篇
  1988年   28篇
  1987年   23篇
  1986年   23篇
  1985年   28篇
  1984年   34篇
  1983年   36篇
  1982年   46篇
  1981年   43篇
  1980年   49篇
  1979年   35篇
  1978年   33篇
  1977年   33篇
  1976年   31篇
  1975年   27篇
  1974年   25篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Leiomyosarcoma of the retrohepatic inferior vena cava is a rare entity and presents a number of diagnostic and therapeutic challenges. Here such a case is presented in which the retrohepatic inferior vena cava was excised after full mobilization of the liver under venovenous bypass. The continuity of the vena cava was restored with cryopreserved aortic homograft. The technical details with regard to total vena caval clamping, venovenous bypass, hepatic inflow occlusion, techniques of reconstruction, including the use of cryopreserved aortic homograft, and a brief review of the literature on the surgical management of retrohepatic inferior vena caval tumors are discussed.  相似文献   
102.
BACKGROUND: The role of local excision for pT2 distal rectal cancer has been challenged because of the observation of high rates of lymph node metastases and local failure. However, neoadjuvant chemoradiation therapy (CRT) has led to increased local disease control and significant tumor downstaging, possibly decreasing rates of lymph node metastases. In this setting, a possible role for local excision of ypT2 has been suggested. METHODS: A total of 401 patients with distal rectal cancer underwent neoadjuvant CRT. Tumor response assessment was performed after at least 8 weeks from CRT completion. One hundred and twelve patients with complete clinical response were not immediately operated on and were excluded from the study, and 289 patients with incomplete clinical response were managed by radical surgery. Patients with final pathological stage ypT2 were analyzed to determine the risk of unfavorable pathological features that could represent unacceptable risk for local failure after local excision. RESULTS: Eighty-eight (30%) patients had ypT2 rectal cancer. Final ypT status was not associated with pretreatment radiological staging (p = 0.62). ypT status was significantly associated with the risk of lymph node metastases, risk of perineural and vascular invasion, and recurrence (p = 0.001). Lymph node metastases were present in 19% of patients with ypT2 rectal cancer. The risk of lymph node metastases in ypT2 was associated with the presence of perineural invasion (47% vs 4%; p = <0.001), vascular invasion (59% vs 6%; p < 0.001), and decreased mean interval CRT surgery (12 vs 18 weeks; p < 0.001), but not with mean tumor size (3.2 vs 3.1 cm; p = 0.8). Disease-free and overall survival rates were significantly better for patients with ypT2N0 (p = 0.02 and 0.006, respectively). Fifty-five (63%) patients with ypT2 had at least one unfavorable pathological feature for local excision (lymph node metastases, vascular or perineural invasion, mucinous type or tumor size >3 cm). CONCLUSION: Lymph node metastases were present in 19% of patients with ypT2 and were significantly associated with poor overall and disease-free survival rates. The risk of lymph node metastases could not be predicted by radiological staging or tumor size. Radical surgery should be considered the standard treatment option for ypT2 rectal cancer after CRT.  相似文献   
103.
Following traumatic brain injury (TBI), cascades of inflammatory processes occur. Laboratory studies implicate the cytokines interleukin-1alpha (IL-1alpha) and IL-1beta in the pathophysiology of TBI and cerebral ischemia, whilst exogenous and endogenous interleukin-1 receptor antagonist (IL-1ra) is neuroprotective. We analyzed IL-1alpha, IL-1beta, and IL-1ra in brain microdialysates (100-kDa membrane) in 15 TBI patients. We also analyzed energy-related molecules (glucose, lactate, pyruvate, glutamate, and the lactate/pyruvate ratio) in these brain microdialysates. Mean of mean (+/-SD) in vitro microdialysis percentage recoveries (extraction efficiencies) were IL-1alpha 19.7+/-7.6%, IL-1beta 23.9+/-10.5%, and IL-1ra 20.9+/-6.3%. In the patients' brain microdialysates, mean of mean cytokine concentrations (not corrected for percentage recovery) were IL-1alpha 5.6+/-14.8 pg/mL, IL-1beta 10.4+/-14.7 pg/mL, and IL-1ra 2796+/-2918 pg/mL. IL-1ra was consistently much higher than IL-1alpha and IL-1beta. There were no significant relationships between IL-1 family cytokines and energy-related molecules. There was a significant correlation between increasing IL-1beta and increasing IL-1ra (Spearman r=0.59, p=0.028). There was also a significant relationship between increasing IL-1ra and decreasing intracranial pressure (Spearman r=-0.57, p=0.041). High concentrations of IL-1ra, and also high IL-1ra/IL-1beta ratio, were associated with better outcome (Mann Whitney, p=0.018 and p=0.0201, respectively), within these 15 patients. It is unclear whether these IL-1ra concentrations are sufficient to antagonize the effects of IL-1beta in vivo. This study demonstrates feasibility of our microdialysis methodology in recovering IL-1 family cytokines for assessing their inter-relationships in the injured human brain, and suggests a neuroprotective role for IL-1ra. It remains to be seen whether exogenous IL-1ra or other agents can be used to manipulate cytokine levels in the brain, for potential therapeutic effect.  相似文献   
104.
105.
The omission of standards for renal length in infants younger than 1 year may result in a statistically significant increase in the frequency of “spurious” nephromegaly. Nonetheless, there are only a few reports specifically dealing with normal kidney dimensions in infants. Based on sonographic assessments performed on a sample of 992 healthy infants, between January 2002 and December 2004, this paper sets up standards for normal kidney dimensions in children aged 0–3 months, 3–6 months, 6–9 months, and 9–12 months and establishes correlations between kidney dimensions (length, width, and volume) and body length and weight. Linear as well as non-linear nomograms, with percentiles for all the kidney variables examined, based on body length, are provided. Also, statistically significant differences in mean values (P = 0.000) for all the observed neonatal kidney parameters, depending on gestational age at birth, are demonstrated. Principal advantages of our nomograms are that they are based on a large number of examined healthy infants and that kidney dimensions are related to body length. In addition, subjects are divided into four sub-annual age groups demonstrating gender-related differences in renal growth dynamics. Our linear nomograms are easier to use for routine clinical practice, but the percentile-based non-linear nomograms we present cover a much wider range of variations in normal infant kidney dimensions.  相似文献   
106.
Two hundred forty-eight constrained condylar total knee arthroplasties consecutively implanted without the use of diaphyseal stem extensions were studied in 180 patients. Preoperative deformity was severe (82% Ahlb?ck grade 4-5). One hundred ninety-two knees (148 patients) were reviewed at mean 47-month follow-up (range: 24-72 months). Knee Society score improved from 36 to 89 points, and function score improved from 42 to 76 points. Failure rate was 2.5% (2 infections, 1 aseptic loosening, 1 supracondylar femoral fracture, and 1 tibial post fracture). Five (2.5%) knees had patellofemoral complications. Nonprogressive radiolucent lines were present in 16% of cases. Use of a nonmodular constrained condylar knee for primary severely damaged knees demonstrated reliable short- to mid-term results with a low complication rate and questioned the routine use of intramedullary stem extensions in all such cases.  相似文献   
107.

Background

Multiple studies have reported favorable short-term outcomes using tantalum cones to reconstruct massive bone defects during revision TKA. However, longer-term followup is needed to determine the durability of these reconstructions.

Questions/purposes

We wished to determine the mid-term (1) reoperation rates for septic and aseptic causes, (2) radiologic findings of osseointegration, and (3) clinical outcomes based on the Knee Society score in patients who underwent revision knee arthroplasty with tantalum cones for severe bone loss.

Methods

We retrospectively evaluated records of 18 patients (18 knees) who underwent revision knee arthroplasty with use of tantalum cones between 2005 and 2008; the primary indications for use of this approach were to reconstruct massive bone defects classified as Anderson Orthopaedic Research Institute Types 2B and 3. During this period, all defects of this type were treated with this approach and no cones were used for more-minor defects. A total of 26 cones (13 tibial and 13 femoral) were implanted. There were 12 female and six male patients with a mean age of 73 years (range, 55–84 years) at the time of revision. The indication for the revision included aseptic loosening (five patients) and second-stage reimplantation for deep infection (13 patients). Patients were followed for a mean of 6 years (range, 5–8 years). No patient was lost to followup. Clinical and radiographic outcomes were assessed with the Knee Society clinical rating system and radiographic evaluation system.

Results

There have been two reoperations for recurrent infection; at surgery, the two cones showed osseointegration. No evidence of loosening or migration of any implant was noted on the most recent radiographs. Knee Society knee scores improved from a mean of 31 points before surgery to 77 points at latest followup (p < 0.001), and function scores improved from a mean of 22 points to 65 points (p < 0.001).

Conclusions

Tantalum cones for reconstruction of massive bone defects in revision knee arthroplasty provided secure fixation with excellent results at average followup of 6 years, although this series included relatively few patients. These devices are a viable option for surgeons to use in situations with severe bone loss. Further studies with longer followups are needed to confirm the durability of these reconstructions.

Level of Evidence

Level IV, therapeutic study.  相似文献   
108.
BackgroundMultivisceral transplant (MVTx) and isolated intestinal transplant (ITx) are complex surgical procedures. The subsequent proinflammatory state in the immediate postoperative period makes interpretation of blood markers difficult.MethodWe aimed to establish the course of various blood markers after MVTx/ITx, and to evaluate their use as diagnostic markers of complications. This was a single center prospective cohort. We analyzed blood markers collected preoperatively, on alternate days for the first postoperative week, and then weekly for 4 weeks. This study was in compliance with The Declaration of Helsinki.ResultsOver a 16-month period (July 2017-October 2018), 20 subjects aged 2 to 67 years with a median age of 24.5 years received MVTx/ITx. Twelve recipients (60%) had an infection. Neutrophil lymphocyte count ratio (NLCR) was higher than established upper limits of normal, regardless of infection status. NLCR and white blood cell count were useful to identify infected MVTx/ITx recipients, with P values <.05 for 2 and 1 of 7 time points post transplant, respectively. Higher preoperative eosinophil% predicted future acute cellular rejection (P value .023).ConclusionsThis is the first study to extensively track the course of blood markers post MVTx/ITx and identified NLCR and white blood cell count as potential diagnostic blood markers of infection.  相似文献   
109.
IntroductionAdenocarcinoma of the esophagogastric junction (AEGJ) represents a poor prognostic tumor. We evaluated the recurrence pattern and risk factors associated with recurrence in patients undergoing surgical resection by AEJG.MethodsRecurrences were categorized as locoregional, peritoneal, or distant. These three recurrence groups and a non-recurrence group were compared, and overall survival (OS) and disease-free survival (DFS) for each one was obtained.ResultsWe analyzed 188 patients with curative surgical treatment. Recurrence was observed in 72 (38.3%) patients. Locoregional recurrence was observed in 17 (23.6%); 20 (27.8%) peritoneal recurrence and 35 (48.6%) distant metastasis. DFS was 9, 5, and 8 months, and OS was 21.8, 13.2, and 20.8, respectively. Tumors larger than 5 cm are risk factors for peritoneal recurrence (OR:2.88, p = 0.012). Positive lymph nodes were related to distant metastasis (OR:9.15, p = 0.040), and lymphatic invasion for locoregional recurrence (OR:3.81, p = 0.028).ConclusionAEGJ is associated with high rates of early recurrence.  相似文献   
110.
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