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   647篇
  免费   42篇
  国内免费   4篇
耳鼻咽喉   1篇
儿科学   41篇
妇产科学   12篇
基础医学   89篇
口腔科学   28篇
临床医学   44篇
内科学   120篇
皮肤病学   16篇
神经病学   11篇
特种医学   144篇
外国民族医学   1篇
外科学   38篇
综合类   50篇
预防医学   36篇
眼科学   5篇
药学   21篇
中国医学   4篇
肿瘤学   32篇
  2021年   8篇
  2020年   6篇
  2019年   5篇
  2018年   13篇
  2017年   11篇
  2016年   14篇
  2015年   12篇
  2014年   18篇
  2013年   31篇
  2012年   25篇
  2011年   19篇
  2010年   43篇
  2009年   44篇
  2008年   23篇
  2007年   20篇
  2006年   9篇
  2005年   7篇
  2004年   5篇
  2003年   4篇
  2002年   3篇
  2001年   5篇
  2000年   5篇
  1999年   7篇
  1998年   34篇
  1997年   33篇
  1996年   34篇
  1995年   35篇
  1994年   23篇
  1993年   20篇
  1992年   4篇
  1991年   4篇
  1990年   7篇
  1989年   15篇
  1988年   14篇
  1987年   10篇
  1986年   13篇
  1985年   9篇
  1984年   12篇
  1983年   14篇
  1982年   12篇
  1981年   13篇
  1980年   15篇
  1979年   4篇
  1978年   8篇
  1977年   2篇
  1976年   8篇
  1975年   5篇
  1955年   1篇
  1950年   1篇
  1949年   1篇
排序方式: 共有693条查询结果,搜索用时 0 毫秒
1.
Falloposcopy in conjunction with laparoscopy: possibilities and limitations   总被引:1,自引:1,他引:1  
Falloposcopy is a transvaginal microendoscopic technique to explore the human Fallopian tube from the uterotubal ostium to the fimbrial end. Falloposcopy provides a unique possibility to visualize endotubal disease and may be used therapeutically for removal of debris and for cutting down filmy intraluminal adhesions. To assess the clinical performance of falloposcopy as part of an infertility investigation, a total of 43 women scheduled for laparoscopy as part of an investigation of infertility had a falloposcopy performed in conjunction with the laparoscopy. All women were investigated at Danderyd Hospital, Stockholm and Akademiska Hospital, Uppsala, during 1995 and 1996. Images from the endosalpinx were obtained in 26 of 43 women (60.5%). In 10 women (23.3%), it was possible to obtain images from both tubes. No images were of sufficient quality to describe the entire tubal mucosa in detail. Falloposcopy represents a unique tool for visualization of endotubal disease and may provide a valuable instrument for in-vivo exploration of tubal physiology. However, certain technical problems limit the usefulness of this method in routine clinical practice. These technical problems have to be solved before falloposcopy can achieve a central position in investigation and treatment of tubal disease.   相似文献   
2.
Interstitial chromosomal deletions at 22q11.2 and 7q11.23 are detected in the vast majority of patients affected by CATCH 22 syndromes and the Williams-Beuren syndrome, respectively. In a group of 15 Williams- Beuren patients, we have shown previously that a large number of 7q11.23 deletions occur in association with an interchromosomal rearrangement, indicative of an unequal crossing-over event between the two homologous chromosomes 7. In this study, we show that a similar mechanism also underlies the formation of the 22q11.2 deletions associated with CATCH 22. In eight out of 10 families with a proband affected by CATCH 22, we were able to show that a meiotic recombination had occurred at the critical deleted region based on segregation analysis of grandparental haplotypes. The incidences of crossovers observed between the closest informative markers, proximal and distal to the deletion, were compared with the expected recombination frequencies between the markers. A significant number of recombination events occur at the breakpoint of deletions in CATCH 22 patients (P = 2.99x10(-7)). The segregation analysis of haplotypes in three- generation families was also performed on an extended number of Williams-Beuren cases (22 cases in all). The statistically significant occurrence of meiotic crossovers (P = 4.45x10(-9)) further supports the previous findings. Thus, unequal meiotic crossover events appear to play a relevant role in the formation of the two interstitial deletions. The recurrence risk for healthy parents in cases where such meiotic recombinations can be demonstrated is probably negligible. Such a finding is in agreement with the predominantly sporadic occurrence of the 22q11.2 and 7q11. 23 deletions. No parent-of-origin bias was observed in the two groups of patients with regard to the origin of the deletion and to the occurrence of inter- versus intrachromosomal rearrangements.   相似文献   
3.
The present study compared the accuracy of ventilation perfusion scintigraphy (VQS) and CT pulmonary angiography (CTPA) for the diagnosis of pulmonary embolism. This was a prospective observational study of 112 patients with suspected pulmonary embolism (PE) who could be studied with both investigations within 24 h. Results were compared to final diagnosis at completion of 6-month follow up, using receiver operating characteristic (ROC) analysis. Pulmonary embolism was diagnosed in 27 referred patients (24%). The sensitivity and specificity of VQS and CTPA were similar to that reported from the literature. A normal VQ scan had the highest negative predictive value (100%), while a high-probability VQ scan had the highest positive predictive value (92%). There was no overall difference (area under the ROC curve (AUC)) between VQS (AUC (95% CI) = 0.82 (0.75,0.89)) and CTPA (AUC = 0.88 (0.81,0.94)) for the diagnosis of PE. Among patients with abnormal chest X-rays, CTPA (AUC 0.90 (0.83,0.97)) appeared somewhat better than VQS (AUC 0.78 (0.68,0.88)) but this difference did not reach statistical significance. In this instance, CTPA is at least as accurate as VQS and may provide an opportunity to make alternative diagnoses.  相似文献   
4.
5.
6.
7.
8.
9.

Purpose

We compared renal function outcomes among patients in the surveillance and intervention arms of the DISSRM registry.

Materials and methods

Patients were grouped into chronic kidney disease stages by estimated glomerular filtration rate range. Cases were considered up staged if a more advanced chronic kidney disease stage was entered during followup. Chronic kidney disease up staging-free survival was compared among groups using Kaplan-Meier analysis and paired comparisons log rank tests. Multivariate Cox regression identified independent predictors of chronic kidney disease up staging-free survival.

Results

A total of 162 patients met the study inclusion criteria, with 68 in the surveillance arm, 65 undergoing partial nephrectomy, 15 undergoing radical nephrectomy, and 14 undergoing cryoablation. Median tumor size was 2.2 cm. Mean estimated glomerular filtration rate change was significantly larger for radical nephrectomy vs. surveillance (?9.2 vs. ?0.5 ml/min/1.73 m2) and for radical vs. partial nephrectomy (?9.2 vs. ?1.9 ml/min/1.73 m2) (P = 0.001). No other groups differed significantly. On Kaplan-Meier analysis, patients undergoing radical nephrectomy had significantly worse chronic kidney disease up staging-free survival vs. those treated with partial nephrectomy (P = 0.029), surveillance (P = 0.007), and cryoablation (P = 0.019). No other groups differed significantly. On multivariate analysis, radical nephrectomy independently predicted poor chronic kidney disease up staging-free survival (odds ratio vs. surveillance 30.6, P = 0.001). Neither partial nephrectomy (P = 0.985) nor cryoablation (P = 0.976) predicted poor chronic kidney disease up staging-free survival relative to surveillance.

Conclusions

Patients in the surveillance arm had superior estimated glomerular filtration rate preservation compared to those in the radical nephrectomy but not the partial nephrectomy arm. In certain patients with small renal masses, surveillance and partial nephrectomy may offer comparable renal functional outcomes. This could be partly attributable to a modest estimated glomerular filtration rate decrease associated with surveillance itself. A thorough understanding of the renal functional impacts of treatment modalities is critical in the management of small renal masses.  相似文献   
10.
Abstract:  The purpose of this study was to assess the predictive value of smoking history on breast cancer diagnosis in a referral clinic population. We conducted a case–control study using clinical data collected on 8,097 female patients (1,225 breast cancer cases and 6,872 controls) seen in the Mayo Clinic Breast Clinic between August 1, 1993 and November 31, 2003. Breast cancer patients and noncancer patients significantly differed with respect to age at time of the index visit (p < 0.001), number of pregnancies (p = 0.006), number of live births (p = 0.002), vital status at last known follow-up (p < 0.001), current menstruation (p < 0.001), age at menopause (p < 0.001), history of hysterectomy (p < 0.001), use of oral contraception (p = 0.05), duration of oral contraception use (p = 0.001), use of other exogenous hormones (p < 0.001), duration of exogenous hormone use (p = 0.05), breast pain at time of index visit (p = 0.002), smoking status (p < 0.001), and use of five or more alcoholic beverages per week (p = 0.002). After adjustment for these baseline characteristics, having a personal history of smoking was found to be predictive of breast cancer diagnosis (odds ratios [OR] = 1.25, p = 0.004). Other positive predictors for breast cancer diagnosis were: age (OR = 1.02, p < 0.001), history of hysterectomy (OR = 0.66, p < 0.001), prior use of oral contraception for more than 11 years (OR = 2.10, p < 0.001), and prior use of other exogenous hormones/estrogen (OR = 1.81, p < 0.001). In this referral practice having a personal history of smoking is predictive of breast cancer diagnosis. Further studies are needed to further explore this relationship.  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