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   12050篇
  免费   638篇
  国内免费   44篇
耳鼻咽喉   75篇
儿科学   315篇
妇产科学   227篇
基础医学   1845篇
口腔科学   124篇
临床医学   1130篇
内科学   2623篇
皮肤病学   294篇
神经病学   1112篇
特种医学   707篇
外国民族医学   3篇
外科学   1460篇
综合类   67篇
一般理论   1篇
预防医学   902篇
眼科学   163篇
药学   739篇
中国医学   35篇
肿瘤学   910篇
  2023年   51篇
  2022年   84篇
  2021年   210篇
  2020年   119篇
  2019年   219篇
  2018年   433篇
  2017年   249篇
  2016年   299篇
  2015年   328篇
  2014年   416篇
  2013年   508篇
  2012年   931篇
  2011年   916篇
  2010年   450篇
  2009年   416篇
  2008年   765篇
  2007年   829篇
  2006年   763篇
  2005年   768篇
  2004年   691篇
  2003年   675篇
  2002年   542篇
  2001年   141篇
  2000年   160篇
  1999年   104篇
  1998年   88篇
  1997年   58篇
  1996年   52篇
  1995年   44篇
  1994年   49篇
  1993年   63篇
  1992年   47篇
  1991年   48篇
  1990年   62篇
  1989年   66篇
  1988年   80篇
  1987年   71篇
  1986年   90篇
  1985年   88篇
  1984年   62篇
  1983年   47篇
  1982年   32篇
  1981年   40篇
  1980年   33篇
  1979年   31篇
  1978年   37篇
  1976年   34篇
  1973年   31篇
  1969年   30篇
  1968年   27篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Outcome of Pregnancies after Biliopancreatic Diversion   总被引:4,自引:0,他引:4  
Background: Severe obesity has deleterious effects on fertility and pregnancy outcomes. Although surgery is the best long-term treatment for severe obesity, there is a risk of gestational undernutrition in operated mothers because bariatric surgery reduces nutrient availability. This is a follow-up report of our initial findings regarding pregnancy and neonatal outcomes in biliopancreatic diversion (BPD) patients, with addition of a new cohort of children born to mothers after BPD. Methods: All women (n = 916) who had successfully undergone BPD in our hospital were mailed a questionnaire containing multiple-choice and essay questions concerning gynecologic and obstetric history, and pregnancy and neonatal outcomes in both preoperative and postoperative pregnancies. Patients operated between 1984 and 1995 (n = 568) were mailed an additional questionnaire regarding children's weight and height progress, and school performance. Perinatal records from our patients' obstetric clinics were also reviewed. Results: The questionnaire was completed by 783 women (85.5%). 251 postoperative pregnancies in 132 women resulted in 166 infants by 109 mothers. 47.0% of patients who were unable to become pregnant preoperatively were successful postoperatively. 90 out of 109 women (82.6%) reported an appropriate weight gain (9.1 ± 5.9 kg) during postoperative pregnancies. The incidence of fetal macrosomia decreased from 34.8 to 7.7%, with a concomitant increase in normalweight babies from 62.1 to 82.7%. The elevated miscarriage rate (26.0%) in these obese women persisted after surgery. Conclusion: Major weight loss following BPD improves the reproductive function of severely obese women. BPD provides major beneficial effects for both mother and child, including normalization of gestational weight changes, reduction of fetal macrosomia, and normalization of the infant's birth-weight. Our results speak in favor of delaying pregnancy in obese women until after the substantial surgical weight loss has occurred.  相似文献   
82.
We investigated differences in judges' attitudes between court-appointed and party-appointed forensic psychiatric expert evidence, including who commissioned the report and how this impacted on the judges' perception of the evidence presented. We also investigated the experts' views on being either a party-appointed or court-appointed expert. This survey has no explicit preconceptions. It sought to gather information empirically. The attitudes towards the experts are seen both from the legal professionals' view and from that of the experts themselves. Two groups, one of 107 forensic psychiatric experts (39 psychologists, 65 psychiatrists and three non-specialist medical doctors), and one of 157 legal professionals (44 judges, 74 attorneys and 39 prosecutors) responded to an online survey. We found that 88% of the experts had been appointed by the court and of these, 73% preferred to be court-appointed. Fifty-one per cent had also been party-appointed and the most common principal was the defence attorney (46%). Sixty-two per cent of the judges who had an opinion stated that the party-appointed experts did not assist the court. This indicates that the judges clearly preferred independent court-appointed experts.  相似文献   
83.
Aim. To describe the association between Alzheimer's disease and seizures by reviewing epidemiological data from available literature and to assess the putative pathophysiological links between neurodegeneration and altered cortical excitability. We also discuss specific antiepileptic treatment strategies in patients with Alzheimer's disease, as well as transient epileptic amnesia as a possible crossroads between degeneration and epilepsy. Methods. Regarding epidemiology, we searched publications in Pubmed, Medline, Scopus and Web of Science (until September 2015) using the keywords “incidence”, “prevalence” and “frequency”, as well as “Alzheimer's disease” and “seizures”. In addition, therapeutic aspects for seizures in Alzheimer's disease were searched using the key words “antiepileptic drugs”, “seizure treatment” and “Alzheimer”. Results. The prevalence and incidence rates of seizures were found to be increased 2 to 6‐fold in patients with Alzheimer's disease compared to age‐adjusted control patients. Treatment strategies have mainly been extrapolated from elderly patients without dementia, except for one single randomised trial, in which levetiracetam, lamotrigine and phenobarbital efficacy and tolerance were investigated in patients with Alzheimer's disease. Mouse models appear to show a major role of amyloid precursor protein and its cleavage products in the generation of cortical hyperexcitability. Conclusion. A link between Alzheimer's disease and epilepsy has long been described and recent cohort studies have more clearly delineated risk factors associated with the genesis of seizures, such as early onset and possibly severity of dementia. As genetic forms of Alzheimer's disease and experimental mouse models suggest, beta‐amyloid may play a prominent role in the propagation of synchronised abnormal discharges, perhaps more via an excitatory mode than a direct neurodegenerative effect.  相似文献   
84.
The increasing use of digitally formatted imaging systems requires high-quality interactive gray-scale computer raster graphics systems for the management, display, and analog film recording of digital image and alphanumeric information. These systems are a combination of computer hardware and software and implement a set of graphics protocols. This paper describes a set of interactive graphics protocols that has been developed for clinical use.  相似文献   
85.

Background

Technetium Tc 99m bone scintigraphy (BS) and contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI) of the pelvis and abdomen are universally recommended for detecting prostate cancer (PCa) metastases in cancer of all stages. However, this two-step approach has limited sensitivity and specificity.

Objective

Evaluate the diagnostic accuracy of whole-body MRI (WBMRI) as a one-step screening test for PCa metastases.

Design, setting, and participants

One hundred consecutive PCa patients at high risk for metastases prospectively underwent WBMRI, CT, and BS completed with targeted x-rays (BS/TXR) in case of equivocal BS. Four independent reviewers reviewed the images.

Measurements

This study compares the diagnostic performance of WBMRI, CT, BS, and BS/TXR in detecting PCa metastases using area under the curve (AUC) receiver operator characteristics. A best valuable comparator (BVC) approach was used to adjudicate final metastatic status in the absence of pathologic evaluation.

Results and limitations

Based on the BVC, 68 patients had metastases. The sensitivity of BS/TXR and WBMRI for detecting bone metastases was 86% and 98–100%, respectively (p < 0.04), and specificity was 98% and 98–100%, respectively. The first and second WBMRI readers respectively identified bone metastases in 7 and 8 of 55 patients with negative BS/TXR. The sensitivity of CT and WBMRI for detecting enlarged lymph nodes was similar, at 77–82% for both; specificity was 95–96% and 96–98%, respectively. The sensitivity of the combination of BS/TXR plus CT and WBMRI for detecting bone metastases and/or enlarged lymph nodes was 84% and 91–94%, respectively (p = 0.03–0.10); specificities were 94–97% and 91–96%, respectively. The 95% confidence interval of the difference between the AUC of the worst WBMRI reading and the AUC of any of the BS/TXR plus CT lay within the noninferiority margin of ±10% AUC.

Conclusions

WBMRI outperforms BS/TXR in detecting bone metastases and performs as well as CT for enlarged lymph node evaluation. WBMRI can replace the current multimodality metastatic work-up for the concurrent evaluation of bones and lymph nodes in high-risk PCa patients.  相似文献   
86.
Study Type – Therapy (multi‐centre retrospective cohort) Level of Evidence 2b What's known on the subject? and What does the study add? Upper urinary tract urothelial carcinomas (UUT‐UCs) are rare tumours. Because of the aggressive pattern of UC, radical nephroureterectomy (RNU) with bladder cuff removal remains the ‘gold‐standard’ treatment. However, conservative strategies, such as segmental ureterectomy (SU) or endourological management, have also been developed in patients with imperative indications. Some teams are now advocating the use of conservative management more commonly in cases of elective indications of UUT‐UCs. Due to the paucity of cases of UUT‐UC, only limited data are available on the oncological outcomes afforded by conservative management. We retrospectively investigated the oncological outcomes after SU and RNU in a large multi‐institutional database. Overall, 52 patients were treated with SU and 416 with RNU. There was no statistical difference between the RNU and SU groups for the 5‐year probability of cancer‐specific survival, recurrence‐free survival and metastasis‐free survival. The type of surgery was not a significant prognostic factor in univariate analysis. The results were the same in a subgroup analysis of only unifocal tumours of the distal ureter with a diameter of <2 cm and of low stage (≤T2). Our results suggest that oncological outcomes after conservative treatment with SU are comparable to RNU for the management of UUT‐UC in select cases.

OBJECTIVE

  • ? To compare recurrence‐free survival (RFS), metastasis‐free survival (MFS) and cancer‐specific survival (CSS) after segmental ureterectomy (SU) vs radical nephroureterectomy (RNU) for urothelial carcinoma (UC) of the upper urinary tract (UUT‐UC) located in the ureter.

PATIENTS AND METHODS

  • ? We performed a multi‐institutional retrospective review of patients with UUT‐UC who had undergone RNU or SU between 1995 and 2010.
  • ? Type of surgery, Tumour‐Node‐Metastasis status, tumour grade, lymphovascular invasion and positive surgical margin were tested as prognostic factors for survival.

RESULTS

  • ? In all, 52 patients were treated with SU and 416 with RNU. The median (range) follow‐up was 26 (10–48) months.
  • ? The 5‐year probability of CSS, RFS and MFS for SU and RNU were 87.9% and 86.3%, respectively (P= 0.99); 37% and 47.9%, respectively (P= 0.48); 81.9% and 85.4%, respectively (P= 0.51).
  • ? In univariable analysis, type of surgery (SU vs RNU) failed to affect CSS, RFS and MFS (P= 0.94, 0.42 and 0.53, respectively).
  • ? In multivariable analyses, pT stage and pN stage achieved independent predictor status for CSS (P= 0.005 and 0.007, respectively); the positive surgical margin and pT stage were independent prognostic factors of RFS and MFS (P= 0.001, 0.04, 0.009 and 0.001, respectively).
  • ? The main limitation of the study is its retrospective design, which is due to the rarity of the disease.

CONCLUSIONS

  • ? Short‐term oncological outcomes after conservative treatment with SU are comparable to RNU for the management of UUT‐UC in select cases and should be considered an option.
  • ? In every other case, RNU still represents the ‘gold standard’ for the treatment of UUT‐UC.
  相似文献   
87.
Freyria AM  Mallein-Gerin F 《Injury》2012,43(3):259-265
Articular cartilage is easily injured but difficult to repair and cell therapies are proposed as tools to regenerate the defects in the tissue. Both differentiated chondrocytes and adult mesenchymal stem cells (MSCs) are regarded as cells potentially able to restore a functional cartilage. However, it is a complex process from the cell level to the tissue end product, during which growth factors play important roles from cell proliferation, extracellular matrix synthesis, maintenance of the phenotype to induction of MSCs towards chondrogenesis. Members of the TGF-β superfamily, are especially important in fulfilling these roles. Depending on the cell type chosen to restore cartilage, the effect of growth factors will vary. In this review, the roles of these factors in the maintenance of the chondrocyte phenotype are discussed and compared with those of factors involved in the repair of cartilage defects, using chondrocytes or adult mesenchymal stem cells.  相似文献   
88.

Purpose

The aim of this pilot study was to describe the hydration and nutritional status of a cohort of elderly dialysis patients and to explore the association between these parameters and the quality of life (QoL).

Methods

All patients over 75?years of age being in chronic dialysis by January 2008 at 3 dialysis units (n?=?34) were asked to participate in this pilot study, 24 patients were entered. Hydration status was assessed by bioimpedance spectroscopy (BIS) and nutritional status by the subjective global assessment (SGA), BIS, anthropometric measures and biochemical parameters. Based on these assessments the patients were classified as being cachectic or not according to newly defined criteria. QoL was measured using the SF-36.

Results

The results showed cachexia in 6 (25?%), 37.5?% had a body mass index below 24, whereas according to SGA 91?% were malnourished. BIS showed low lean tissue index in 46?% and overhydration in 35?% of the patients. Compared to non-cachectic and normohydrated, cachectic and overhydrated patients reported consistently poorer QoL. For cachectic patients, the differences were clinically significant for all SF-36. BIS was easily applicable when used before dialysis.

Conclusions

The high frequency of nutritional deficits in this study calls for more attention to nutritional status in elderly dialysis patients. There is a need for a general agreement on how nutritional status should be assessed and reported, both in clinics and in research.  相似文献   
89.
Although optical colonoscopy is still the gold standard for diseases of the colon, radiologic examination of the colon is now being performed by CT scan. Evaluation of the colon is enhanced by distension, which "de-folds" the intestinal wall, thus facilitating its examination for abnormalities of the mucosa, the wall as a whole, and the diameter of the bowel lumen. Water or gas (CO(2)) may be used for the distension, depending on the suspected lesions. The water enema method of colonography combines filling the bowel lumen with water and intravenous injection of a contrast medium. It is indicated when there is a clinical suspicion of colon cancer, or for initial discovery of liver metastases, and for staging of colon tumors. This technique, which requires little or no colon cleansing preparation, can be performed with no special equipment and has a short learning curve. The gas enema method of colonography, or virtual colonoscopy, is performed by distending the colon with CO(2), without any intravenous injection of contrast medium. Its purpose is to detect polyps as part of a screening for precancerous growths. This technique, which does require bowel cleansing preparation, uses a dedicated console for reading and requires specific training.  相似文献   
90.

Purpose

BRAF V600 mutations are frequent in melanomas, and BRAFV600-targeted therapy have dramatic, but often transitory, efficacy in stage IV patients. Prognosis of patients with American Joint Committee on Cancer (AJCC) stage III melanoma is heterogeneous. We aimed to determine the overall survival (OS) of stage III patients with a nodal deposit of ??2?mm according to BRAF V600 mutations and other previously reported prognostic criteria.

Methods

This retrospective study included 105 consecutive patients with stage III cutaneous melanomas. Most patients underwent a prospective follow-up. BRAF V600 mutations were detected by sequencing and pyrosequencing of DNA in samples containing >60?% melanoma cells.

Results

BRAF mutations (p.V600E and p.V600K in 83 and 14?% of cases, respectively) were detected in 40?% of the patients. For patients with and without BRAF mutations, death occurred in 83.3 and 60.3?%, with a median OS of 1.4 and 2.8?years, respectively. Patient age, primary melanoma ulceration, number of invaded lymph nodes, AJCC staging at study entry, and BRAF status were linked to OS in the univariate analysis. The only characteristics associated with OS in the multivariate analysis were number of invaded lymph nodes (P?=?0.005, hazard ratio 2.2, 95?% confidence interval 1.3?C3.9) and BRAF status (P?=?0.005, hazard ratio 1.9, 95?% confidence interval 1.2?C3.1).

Conclusions

BRAF V600 status could be used to stage melanoma patients with nodal deposits. Our results may also help to plan adjuvant trials in these patients, for whom the low tumor load may induce longer efficacy of BRAF-targeted therapies.  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