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   345篇
  免费   22篇
  国内免费   1篇
儿科学   18篇
妇产科学   3篇
基础医学   32篇
口腔科学   5篇
临床医学   32篇
内科学   56篇
皮肤病学   7篇
神经病学   17篇
特种医学   21篇
外科学   56篇
综合类   68篇
预防医学   24篇
眼科学   1篇
药学   8篇
肿瘤学   20篇
  2023年   3篇
  2022年   2篇
  2021年   20篇
  2020年   3篇
  2019年   7篇
  2018年   12篇
  2017年   6篇
  2016年   9篇
  2015年   11篇
  2014年   16篇
  2013年   24篇
  2012年   17篇
  2011年   17篇
  2010年   15篇
  2009年   10篇
  2008年   11篇
  2007年   5篇
  2006年   7篇
  2005年   4篇
  2004年   9篇
  2003年   7篇
  2002年   6篇
  2001年   6篇
  2000年   3篇
  1999年   9篇
  1998年   7篇
  1997年   8篇
  1996年   5篇
  1995年   4篇
  1993年   8篇
  1992年   6篇
  1991年   2篇
  1990年   8篇
  1989年   6篇
  1988年   5篇
  1987年   5篇
  1986年   4篇
  1985年   4篇
  1984年   2篇
  1982年   6篇
  1981年   7篇
  1980年   2篇
  1979年   8篇
  1978年   5篇
  1977年   11篇
  1976年   3篇
  1972年   4篇
  1952年   1篇
  1940年   1篇
  1934年   1篇
排序方式: 共有368条查询结果,搜索用时 15 毫秒
31.
Care provider assessment of intrathecal baclofen in children   总被引:2,自引:0,他引:2  
Intrathecal baclofen is used increasingly to manage severe spasticity in children. Before implanting the baclofen pump, care providers typically ask how it will benefit their child. The purpose of this study was to describe the perceptions of care providers about intrathecal baclofen for management of spasticity in 80 individuals (52 males, 28 females). The individuals were younger than 22 years at the time of implantation (mean age 11 years, SD 5 years; range 3 to 21 years). Participants had been implanted with the pump for a minimum of one year at the time of evaluation. The most common diagnoses were quadriplegic and diplegic cerebral palsy and traumatic brain injury. Most participants were at level IV and V on the Gross Motor Function Classification System. After pump implantation most participants had tone reduction on the Ashworth scale of 1 to 1.9 in the lower extremities and 0 to 0.9 in the upper extremities. Lower extremity range of motion was maintained in 43 of 51 individuals (84%) and lost in 8 participants (16%). Complications requiring surgery occurred in 63 of a larger group of 152 patients (incidence per patient-year of follow-up was 0.19). Thirty-one of the 80 children had orthopedic procedures after pump placement. Only one of these was unexpected and none had rapid progression of scoliosis. Most treatment goals were achieved. Goals most commonly chosen (decreased pain, prevention of worsening of deformity, and improved ease of care) were improved in 91%, 91%, and 88% of participants respectively. Ninety-five per cent of care providers agreed that they would have this procedure performed again (81% strongly agreed, 14% slightly agreed). All care providers reported improvement in scores on the Caregiver Questionnaire. This information has been helpful to families considering intrathecal baclofen therapy.  相似文献   
32.
When Oregon shifted to managed care for Medicaid-funded substance abuse treatment, standardized patient placement and discharge criteria were rapidly implemented statewide. This prospective, naturalistic study examines the validity and impact of placement criteria with a sample of 240 adults presenting for treatment compared to a sample of 287 in Washington state, where implementation was phased in slowly. Baseline profile analysis suggested better differentiation between Level II and Level III clients for the Oregon sample and better implementation than with the Washington sample, presumably because Oregon clinicians received more training and had more experience with the criteria. A majority of the Oregon sample was placed in intensive outpatient programs, consistent with the recommended level of care. In this study, placement criteria showed good potential for changing treatment planning behavior, increasing individualization, and improving utilization of new levels of care.  相似文献   
33.
Seven schools in Lower Saxony participated in a scientific re-search project measuring the concentration of carbon dioxide (CO2), indoor air temperatures and the relative air humidity in naturally ventilated classrooms on 58 days during the period of one year. The results are as follows: The hygienic reference value of 1500 ppm CO2 (in accordance with the official German regulation DIN 1946-2) was exceeded on 7 days in summer when measurements were taken (32% of all samples in summer) and on 32 days in winter (89% of all samples in winter). The mean CO2-concentration was 1316 ppm, 766 ppm and 1652 ppm in all samples (58 measuring days), summer samples (22 measuring days) and winter samples (36 measuring days), respectively. The mean indoor air temperature was 21.7 degrees C, 22.9 degrees C and 20.9 degrees C. The mean relative humidity was 50.7%, 54.3% and 48.5%. The mean number of persons per classroom (including the teacher) was 25.1, corresponding to a mean volume of 8.5 m3 for each person and a mean area of 2.9 m2 per person. A statistical association of CO2 concentration with season, outdoor temperature and the age of the windows was found. A software programme has been developed for calculating the concentration of CO2 depending on the number of persons and the ventilation rate in a classroom. A 3-level scheme based on CO2 concentration was developed to assess the air quality. The results showed that the classrooms were not ventilated regularly but depending on the outdoor temperature and the season. Deficits concerning all 3 parameters were found. It is very likely that the deficits are not limited to the schools participating in this project. Ventilation and indoor climate deficits might cause health problems and therefore lead to costly measurement programmes. To enable schools to take their own health-related measurements, measuring instruments were purchased which can be loaned to schools in Lower Saxony.  相似文献   
34.
Chromosomal inversions and the reproductive isolation of species   总被引:27,自引:0,他引:27       下载免费PDF全文
Recent genetic studies have suggested that many genes contribute to differences between closely related species that prevent gene exchange, particularly hybrid male sterility and female species preferences. We have examined the genetic basis of hybrid sterility and female species preferences in Drosophila pseudoobscura and Drosophila persimilis, two occasionally hybridizing North American species. Contrary to findings in other species groups, very few regions of the genome were associated with these characters, and these regions are associated also with fixed arrangement differences (inversions) between these species. From our results, we propose a preliminary genic model whereby inversions may contribute to the speciation process, thereby explaining the abundance of arrangement differences between closely related species that co-occur geographically. We suggest that inversions create linkage groups that cause sterility to persist between hybridizing taxa. The maintenance of this sterility allows the species to persist in the face of gene flow longer than without such inversions, and natural selection will have a greater opportunity to decrease the frequency of interspecies matings.  相似文献   
35.
The first wave of the German Health Interview and Examination Survey for Adults, 2008–2011 (DEGS1), assesses current medicine use among participating adults aged 18–79 years in the 7 days prior to the medical examination as part of a standardised interview. About three quarters (74.4?%) of all men and women state that they used at least one preparation. Prevalence is highest among 70–79 year olds (men 94.9?%; women 96.3?%). Overall women have a significantly higher prevalence rate (85.4?%) than men (63.8?%). Preparations for the treatment of cardiovascular diseases are the most frequently used medicines (men 27.2?%; women 29.5?%). Polypharmacy (the use of 5 or more preparations) increases continuously with age and is observed significantly more often in women than in men in all age groups with the exception of the age group 70–79. Of the 20,084 recorded preparations, 71.8?% are prescribed by a doctor and 27.7?% are self-medicated. While there are no differences in overall medication linked to social status, a social gradient is observed in prescribed preparations and self-medication. The results presented here describe key indicators of medication use representative of the German adult population. Based on the extensive data of DEGS1, further analyses into aspects such as co- and multimedication will be addressed in the future. An English full-text version of this article is available at SpringerLink as supplemental.  相似文献   
36.
37.
The purpose of this article is to increase faculty awareness and understanding of the constraints and contradictions that are embedded within faculty work load formulas. An overview of critical social theory is presented and serves as a framework for the analysis of work load formulas within the context of their historical development and current usage. The ideologies, constraints, and interests of such formulas are identified and explored. Challenges exist to beliefs that faculty work load formulas are a just and equitable way to determine faculty responsibilities; that faculty worth can be objectified, categorized, quantified, and measured; and that the institutional norms and values of higher education are right for nursing. The feminist PEACE (praxis, empowerment, awareness, consensus, and evolvement) process, as developed by Wheeler and Chinn, is discussed and serves as a framework for the development of alternative methods to create autonomy, responsibility, and greater communication in establishing faculty work loads. The authors believe that only through awareness, reflection, understanding, and action can the tensions that create conflict and perpetuate dominance and authority be changed.  相似文献   
38.

Background

Whereas the Scottish guidelines are audited annually, nobody evaluates guideline compliance in Germany. Thus, can external quality assurance data pursuant to section 137 of the German Social Code Book V be suitable for auditing guideline compliance?

Materials and methods

From North Rhine Westphalia, a total of 48,831 cases of femoral fractures near the hip joint were evaluated. Compliance with the guidelines was determined based on preoperative hospital stay, thrombosis, and antibiotic prophylaxis. Guideline rationale was reviewed in terms of mortality and thromboembolism rate.

Results

Sixty-four percent of the interventions were performed in a timely manner. Thrombosis prophylaxis was given in 99% of cases. Antibiotics were given as a single shot. There was no connection between mortality and thromboembolism rates or time to surgery.

Conclusion[Überschrift]

Guideline compliance is similar in German and Scotland. The external quality assurance data are suitable for evaluating guideline compliance. The literature recommends a short time to surgery. Given the short observation period, it was not possible to demonstrate any improvement in outcomes.  相似文献   
39.

Purpose

This study reviews adrenocortical tumors in children to determine factors that significantly affect outcome.

Methods

An institutional review board-approved retrospective review from 1976 to 2005 identified 23 patients younger than 19 years old with histologic confirmation of adrenocortical carcinoma (ACC) and adenomas.

Results

The mean age of the 23 children was 9.0 ± 1.6 years; girls predominated (female-to-male ratio = 1.9:1) as did cancers (ACC 16, adenoma 7); tumor hormone production (74%); and advanced stage for disease (66%). All malignancies were more than 2.5 cm. Adrenalectomy, including en bloc resection of adjacent structures (35%) achieved grossly negative margins in 70% of patients. Three patients received chemotherapy or chemoradiation as primary treatment without surgery. There was no perioperative mortality; morbidity was 10% (pneumothorax, acute renal failure, chylous ascites, and thrombocytosis). Surgical cure without adjuvant therapy was achieved for all adenomas and ACC stages I and II. For ACC stage III and IV, median survival was 21 months, 5-year survival was 0%. All advanced-staged ACC received adjuvant therapy. Surgically negative margins conferred a survival advantage.

Conclusions

Children, especially females with ACC present with large advanced-staged tumors. Surgically negative margins with or without en bloc resection improves survival. The high percentage of children with functioning tumors suggests earlier detection is possible.  相似文献   
40.
The tumour suppressor gene PTEN , which maps to 10q23.3 and encodes a 403 amino acid dual specificity phosphatase (protein tyrosine phosphatase; PTPase), was shown recently to play a broad role in human malignancy. Somatic PTEN deletions and mutations were observed in sporadic breast, brain, prostate and kidney cancer cell lines and in several primary tumours such as endometrial carcinomas, malignant melanoma and thyroid tumours. In addition, PTEN was identified as the susceptibility gene for two hamartoma syndromes: Cowden disease (CD; MIM 158350) and Bannayan-Zonana (BZS) or Ruvalcaba-Riley-Smith syndrome (MIM 153480). Constitutive DNA from 37 CD families and seven BZS families was screened for germline PTEN mutations. PTEN mutations were identified in 30 of 37 (81%) CD families, including missense and nonsense point mutations, deletions, insertions, a deletion/insertion and splice site mutations. These mutations were scattered over the entire length of PTEN , with the exception of the first, fourth and last exons. A 'hot spot' for PTEN mutation in CD was identified in exon 5 that contains the PTPase core motif, with 13 of 30 (43%) CD mutations identified in this exon. Seven of 30 (23%) were within the core motif, the majority (five of seven) of which were missense mutations, possibly pointing to the functional significance of this region. Germline PTEN mutations were identified in four of seven (57%) BZS families studied. Interestingly, none of these mutations was observed in the PTPase core motif. It is also worthy of note that a single nonsense point mutation, R233X, was observed in the germline DNA from two unrelated CD families and one BZS family. Genotype-phenotype studies were not performed on this small group of BZS families. However, genotype-phenotype analysis inthe group of CD families revealed two possible associations worthy of follow-up in independent analyses. The first was an association noted in the group of CD families with breast disease. A correlation was observed between the presence/absence of a PTEN mutation and the type of breast involvement (unaffected versus benign versus malignant). Specifically and more directly, an association was also observed between the presence of a PTEN mutation and malignant breast disease. Secondly, there appeared to be an interdependent association between mutations upstream and within the PTPase core motif, the core motif containing the majority of missense mutations, and the involvement of all major organ systems (central nervous system, thyroid, breast, skin and gastrointestinal tract). However, these observations would need to be confirmed by studying a larger number of CD families.   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