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   1207篇
  免费   55篇
  国内免费   1篇
耳鼻咽喉   11篇
儿科学   47篇
妇产科学   83篇
基础医学   113篇
口腔科学   34篇
临床医学   97篇
内科学   227篇
皮肤病学   4篇
神经病学   208篇
特种医学   46篇
外科学   148篇
综合类   1篇
预防医学   37篇
眼科学   12篇
药学   136篇
肿瘤学   59篇
  2023年   13篇
  2022年   14篇
  2021年   27篇
  2020年   15篇
  2019年   29篇
  2018年   17篇
  2017年   19篇
  2016年   19篇
  2015年   39篇
  2014年   40篇
  2013年   37篇
  2012年   76篇
  2011年   81篇
  2010年   45篇
  2009年   37篇
  2008年   68篇
  2007年   80篇
  2006年   76篇
  2005年   66篇
  2004年   63篇
  2003年   44篇
  2002年   44篇
  2001年   32篇
  2000年   27篇
  1999年   28篇
  1998年   14篇
  1997年   9篇
  1996年   10篇
  1995年   12篇
  1994年   10篇
  1993年   11篇
  1992年   18篇
  1991年   28篇
  1990年   15篇
  1989年   12篇
  1988年   12篇
  1987年   13篇
  1986年   9篇
  1985年   8篇
  1984年   6篇
  1983年   5篇
  1982年   7篇
  1981年   5篇
  1980年   2篇
  1978年   2篇
  1977年   3篇
  1976年   3篇
  1975年   3篇
  1974年   2篇
  1959年   1篇
排序方式: 共有1263条查询结果,搜索用时 31 毫秒
1.
It is advised that individuals should avoid losing >2% of their body mass during exercise in order to prevent hyperthermia. This study sought to assess whether a loss of >2% body mass leads to elevations in core temperature during an ultramarathon. Thirty runners agreed to take part in the study. Body mass and core temperature were measured at the start, at three locations during the race and the finish. Core temperature was not correlated with percent body mass change (p = 0.19) or finish time (p = 0.11). Percent body mass change was directly associated with finish time (r = 0.58, p < 0.01), such that the fastest runners lost the most mass (~3.5–4.0%). It appears that a loss of >3% body mass does not contribute to rises in core temperature. An emphasis on fluid replacement for body mass losses of this magnitude during prolonged exercise is not justified as a preventative measure for heat-related illnesses.  相似文献   
2.
3.
No data in the literature report the specific invasion of the orbit from ethmoidal tumors, although such a pattern of involvement of the orbit frequently occurs because of the thin lamina papyracea separating the two structures. From January 1986 to January 2003, 38 patients with untreated primary ethmoidal malignancies were observed at the Unit of Maxillo-Facial Surgery of the University "La Sapienza" in Rome. Personal data were obtained from review of the personal clinical file of each. Orbital invasion was present in 24 patients with ethmoidal malignancy. Three stages of orbital invasion were identified. The average overall survival, with the Kaplan-Meyer method, was 61.4% after 1 year and 51.1% at 5 and 10 years. Intracranial involvement is the main element for short-term negative prognosis. Orbital exenteration is fundamental if grade III orbital invasion occurs because it ensures an improvement of the disease-free survival.  相似文献   
4.
A patient was treated with a maxillary gold-palladium alloy fixed partial denture (FPD). Shortly after placement, the patient contracted severe contact mucositis. Patch-testing revealed a positive reaction to palladium chloride (PdCl 2 , 1% petrolatum) but not to any other component of the prosthesis. After removal of the FPD and placement of a provisional acrylic resin restoration, all signs and symptoms disappeared. A definitive metal-ceramic (titanium-porcelain) prosthesis was placed, and no signs of lesions appeared. This clinical report demonstrates that titanium may be a satisfactory alternative for patients who require prostheses and are sensitive to other metals.  相似文献   
5.
Neuropeptide K-like immunoreactivity in human dental pulp   总被引:1,自引:0,他引:1  
Nerve fibres displaying such immunoreactivity were revealed by indirect immunofluorescence. Neuropeptide K-like immunoreactive fibres, entering the pulp within large nerve trunks, were distributed around blood vessels as well as in the stroma. Some immunoreactive fibres were also observed in the para-odontoblastic region. In view of the biological activity of neuropeptide K, it is tentatively proposed that it may act in the dental pulp as a regulatory peptide involved in neurogenic inflammation, blood flow regulation and sensory transmission.  相似文献   
6.
OBJECTIVE: The present study aimed at evaluating different restoring configurations of a crownless maxillary central incisor, in order to compare the biomechanical behavior of the restored tooth with that of a sound tooth. MATERIALS AND METHODS: A 3D FE model of a maxillary central incisor is presented. An arbitrary static force of 10 N was applied with an angulation of 125 degrees to the tooth longitudinal axis at level of the palatal surface of the crown. Different material configurations were tested: composite, syntered alumina, feldspathic ceramic endocrowns and glass post resorations with syntered alumina and feldspathic ceramic crown. RESULTS: High modulus materials used for the restoration strongly alter the natural biomechanical behavior of the tooth. Critical areas of high stress concentration are the restoration-cement-dentin interface both in the root canal and on the buccal and lingual aspects of the tooth-restoration interface. Materials with mechanical properties underposable to that of dentin or enamel improve the biomechanical behavior of the restored tooth reducing the areas of high stress concentration. SIGNIFICANCE: The use of endocrown restorations present the advantage of reducing the interfaces of the restorative system. The choice of the restorative materials should be carefully evaluated. Materials with mechanical properties similar to those of sound teeth improve the reliability of the restoartive system.  相似文献   
7.
Myoclonus is a possible manifestation of mitochondrial disorders, and its presence is considered, in association with epilepsy and the ragged red fibers, pivotal for the syndromic diagnosis of MERRF (myoclonic epilepsy with ragged red fibers). However, its prevalence in mitochondrial diseases is not known. The aims of this study are the evaluation of the prevalence of myoclonus in a big cohort of mitochondrial patients and the clinical characterization of these subjects. Based on the database of the “Nation‐wide Italian Collaborative Network of Mitochondrial Diseases,” we reviewed the clinical and molecular data of mitochondrial patients with myoclonus among their clinical features. Myoclonus is a rather uncommon clinical feature of mitochondrial diseases (3.6% of 1,086 patients registered in our database). It is not strictly linked to a specific genotype or phenotype, and only 1 of 3 patients with MERRF harbors the 8344A>G mutation (frequently labeled as “the MERRF mutation”). Finally, myoclonus is not inextricably linked to epilepsy in MERRF patients, but more to cerebellar ataxia. In a myoclonic patient, evidences of mitochondrial dysfunction must be investigated, even though myoclonus is not a common sign of mitochondriopathy. Clinical, histological, and biochemical data may predict the finding of a mitochondrial or nuclear DNA mutation. Finally, this study reinforces the notion that myoclonus is not inextricably linked to epilepsy in MERRF patients, and therefore the term “myoclonic epilepsy” seems inadequate and potentially misleading. © 2014 International Parkinson and Movement Disorder Society  相似文献   
8.
This multi-center Italian prospective observational study reports the 4 months follow-up data of 87 patients affected by chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and multifocal motor neuropathy (MMN) shifted from intravenous to subcutaneous immunoglobulin treatment. A therapeutic shift from intravenous to subcutaneous immunoglobulin was performed in 87 patients (66 CIDP; 21 MMN) affected by immune-mediated peripheral neuropathies with evidence of a sustained clinical response to intravenous immunoglobulin. Patients were evaluated by means of the Overall Neuropathy Limitation Scale, Medical Research Council Scale and Life Quality Index questionnaire, both at the time of therapeutic shift and after 4 months of subcutaneous immunoglobulin treatment. A sustained clinical efficacy was observed after the switch to subcutaneous immunoglobulin: the Overall Neuropathy Limitation Scale score improved in the group of 66 CIDP patients (P = 0.018), with only one subject reporting a worsening of 1 point, and remained stable in the group of 21 MMN patients (P = 0.841), with one subject reporting a worsening of two points. An improvement in the patient’s perception of therapeutic setting was reported in both groups. This large multi-center study confirms the short-term clinical equivalence of subcutaneous versus intravenous immunoglobulin and a possible improvement in the patient’s perception of therapeutic setting with the subcutaneous administration. However, further studies are required to extend the results to a longer observational period.  相似文献   
9.
10.

Background

Actual predictors of survival and recurrence for rectal cancer patients undergoing curative resection mostly come from pathological data of surgical specimen. Recently, novel blood biomarkers have been proposed as useful tools in cancer patient management, but few and conflicting data have been reported in rectal cancer. We evaluated the prognostic relevance of preoperative platelet-to-lymphocyte (P/L) ratio and neutrophil-to-lymphocyte (N/L) ratio on survival and recurrence in patients undergoing laparoscopic curative resection for rectal cancer.

Methods

All consecutive patients who referred for primary rectal disease to the Department of General Surgery in Cittadella (Italy) from June 2005 to September 2015 were retrospectively evaluated. Patients with metastatic disease at surgery were excluded. P/L and N/L ratios were calculated. For patients undergoing neoadjuvant chemo-radiotherapy, pre-treatment data were considered. Follow-up data were updated at December 2016.

Results

One hundred fifty-two patients were included in the study, 49 (32%) received neoadjuvant chemo-radiotherapy. Both P/L and N/L ratios showed poor discriminative performance on 5-year OS and DFS. Time-dependent ROC curves showed no improvements in discriminative performance of P/L and N/L ratios when considering different time endpoints. Multivariable analysis identified CEA—rather than P/L or N/L ratios—as independent predictor of OS and DFS, adjusting for age, tumor stage, and postoperative morbidity.

Conclusion

Neither P/L nor N/L ratios were associated with survival after rectal cancer surgery. Further studies on large series might provide insights on the role of these inexpensive blood biomarkers in rectal cancer.
  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