全文获取类型
收费全文 | 1252篇 |
免费 | 98篇 |
国内免费 | 16篇 |
专业分类
耳鼻咽喉 | 96篇 |
儿科学 | 28篇 |
妇产科学 | 20篇 |
基础医学 | 143篇 |
口腔科学 | 19篇 |
临床医学 | 93篇 |
内科学 | 196篇 |
皮肤病学 | 5篇 |
神经病学 | 99篇 |
特种医学 | 169篇 |
外科学 | 155篇 |
综合类 | 33篇 |
预防医学 | 77篇 |
眼科学 | 54篇 |
药学 | 55篇 |
肿瘤学 | 124篇 |
出版年
2023年 | 3篇 |
2022年 | 6篇 |
2021年 | 15篇 |
2020年 | 7篇 |
2019年 | 13篇 |
2018年 | 28篇 |
2017年 | 15篇 |
2016年 | 19篇 |
2015年 | 20篇 |
2014年 | 35篇 |
2013年 | 39篇 |
2012年 | 69篇 |
2011年 | 56篇 |
2010年 | 25篇 |
2009年 | 38篇 |
2008年 | 57篇 |
2007年 | 62篇 |
2006年 | 44篇 |
2005年 | 51篇 |
2004年 | 67篇 |
2003年 | 35篇 |
2002年 | 18篇 |
2001年 | 37篇 |
2000年 | 29篇 |
1999年 | 34篇 |
1998年 | 34篇 |
1997年 | 35篇 |
1996年 | 33篇 |
1995年 | 20篇 |
1994年 | 27篇 |
1993年 | 19篇 |
1992年 | 25篇 |
1991年 | 31篇 |
1990年 | 34篇 |
1989年 | 38篇 |
1988年 | 29篇 |
1987年 | 22篇 |
1986年 | 21篇 |
1985年 | 24篇 |
1984年 | 16篇 |
1983年 | 27篇 |
1982年 | 21篇 |
1981年 | 21篇 |
1980年 | 16篇 |
1979年 | 10篇 |
1978年 | 9篇 |
1977年 | 11篇 |
1976年 | 9篇 |
1975年 | 3篇 |
1963年 | 2篇 |
排序方式: 共有1366条查询结果,搜索用时 15 毫秒
81.
BACKGROUND: Computer assisted surgery (CAS) permits the visualization of hidden bony covered structures invisible for the human eye with radiological 3d data sets. The surgeon might be able to orientate anatomically during surgery without having to prepare the according landmarks. This would mean less surgical traumatization and a shorter and smaller operation corridor. METHOD: We determined the use of CAS in a quality assurance analysis with the subtemporal approach in 8 patients with supra-meatal tumors type A of the cerebellopontine angle. Various navigation systems and methods for referencing for the registration of the patients' heads were used. The question was whether it is possible intraoperatively without preparation of known anatomical landmarks to define the borders of an optimal positioned temporary bone cap and to identify the bony covered inner auditory canal and its neuronal structures without orienting neurostimulation. RESULT: It was possible with CAS to assess intraoperatively the borders of a temporary bone cap above the cranially positioned mastoid cell. However, the objective inaccuracy of 2 to 28 mm observed during surgery did not allow a secure identification of the inner auditory canal. CONCLUSIONS: CAS with the subtemporal approach cannot replace the conventional preparation of known anatomical landmarks nor neurostimulation to identify neural structures, due to the expected high inaccuracy with the non-invasive referencing systems that are available today. 相似文献
82.
83.
Vis JC Schipper E de Boer-van Huizen RT Verbeek MM de Waal RM Wesseling P ten Donkelaar HJ Kremer B 《Acta neuropathologica》2005,109(3):321-328
Inappropriate apoptosis has been implicated in the mechanism of neuronal death in Huntingtons disease (HD). In this study, we report the expression of apoptotic markers in HD caudate nucleus (grades 1–4) and compare this with controls without neurological disease. Terminal transferase-mediated biotinylated-UTP nick end-labeling (TUNEL)-positive cells were detected in both control and HD brains. However, typical apoptotic cells were present only in HD, especially in grade 3 and 4 specimens. Expression of the pro-apoptotic protein Bax was increased in HD brains compared to controls, demonstrating a cytoplasmic expression pattern in predominantly shrunken and dark neurons, which were most frequently seen in grades 2 and 3. Control brains displayed weak perinuclear expression of the anti-apoptotic protein Bcl-2, whereas in HD brains Bcl-2 immunoreactivity was markedly enhanced, especially in severely affected grade 4 brains, and was observed in both healthy neurons and dark neurons. Caspase-3, an executioner protease, was only found in four HD brains of different grades and was not expressed in controls. A strong neuronal and glial expression of poly(ADP-ribose) polymerase (PARP)-immunoreactivity was observed in HD brains. These data strongly suggest the involvement of apoptosis in HD. The exact apoptotic pathway occurring in HD neurodegeneration remains yet unclear. However, the presence of late apoptotic events, such as enhanced PARP expression and many TUNEL-positive cells accompanied with weak caspase-3 immunoreactivity in severely affected HD brains, suggests that caspase-mediated neuronal death only plays a minor role in HD. 相似文献
84.
Beneficial effect of helicopter emergency medical services on survival of severely injured patients 总被引:1,自引:0,他引:1
Frankema SP Ringburg AN Steyerberg EW Edwards MJ Schipper IB van Vugt AB 《The British journal of surgery》2004,91(11):1520-1526
BACKGROUND: In Rotterdam, the Netherlands, a helicopter-transported medical team (HMT), staffed with a trauma physician, provides additional therapeutic options at the scene of injury. This study evaluated the influence of the HMT on the chance of survival of severely injured trauma victims. METHODS: This was a 2-year prospective observational study of consecutive adults who suffered multiple trauma (Injury Severity Score (ISS) 16 or more) and presented to the Erasmus Medical Centre emergency ward. The effect of the HMT was quantified by an odds ratio (OR), adjusted for confounding variables in logistic regression models. RESULTS: Complete data for a total of 346 patients were available for analysis. Two hundred and thirty-nine patients were treated by ambulance personnel alone and 107 received additional HMT assistance. Patients in the HMT group had significantly lower Glasgow Coma Scale scores (mean 8.9 versus 10.6; P = 0.001) and a higher ISS (mean 30.9 versus 25.3; P < 0.001). The unadjusted OR for death was 1.7 in favour of the group treated by ambulance staff only (OR for survival 0.61 (95 per cent confidence interval (c.i.) 0.37 to 1.0, P = 0.048)). After adjustment, however, patients in the HMT group had an approximately twofold better chance of survival (all injuries: OR 2.2 (95 per cent c.i. 0.92 to 5.9), P = 0.076; blunt injuries: OR 2.8 (95 per cent c.i. 1.07 to 7.52), P = 0.036). CONCLUSION: The presence of the HMT may increase chances of survival for patients suffering multiple trauma, especially for those with blunt trauma. 相似文献
85.
BACKGROUND: Endolymphatic sac tumours (ELST) have only been known as own tumour entities since 1984. ELST might occur solitarily and sporadically as well as hereditary connected to von Hippel-Lindau disease (VHL). This connection has been observed in 1992 for the first time and confirmed by molecular genetic analyses of the VHL gen. There is no agreement yet concerning diagnostics and therapy. METHODS: Our attempt of classifying this type of tumour is the first one. According to our own experience and to literature, we suggest the following classification: ELST type A is locally confined without erosions of the temporal bone nor infiltration of the subarachnoidal area; ELST type B with bony infiltration of the labyrinth block and clinical hearing loss, and ELST type C with additional infiltration of the sigmoid sinus and the vein of jugular bulb. Preoperative diagnostics are performed according to defined radiological criteria in CT and MRI scans including MR-angiography. RESULTS: In 6 patients, including two with a VHL syndrome, ELST was completely sanitized by stage-compatible surgery, using translabyrintine to infratemporal approaches, according to the tumour classification that we developed. The VII (th) nerve could be saved in all tumour stages, and in stage ELST type A the VIII (th) nerve as well. All patients remained without local recurrence in MRI check during the observation period of 4 to 38 months. CONCLUSION: Our stage-compatible surgery of ELST allows total tumor removal with minor morbidity. In contrast to the antero-, retrosigmoidal and suboccipital approaches, the tumour matrix can be safely removed via transmastoidal approach to exclude local recurrences. 相似文献
86.
Electrophysiologic examinations in low frequency hearing impairment: clinical and prognostic aspects
Maier W Aschendorff A Arapakis I Klenzner T Schipper J 《Laryngo- rhino- otologie》2004,83(12):824-830
INTRODUCTION: Low-frequency hearing impairment (LFHI) is mainly associated to endolymphatic hydrops and shows a high variety of possible outcomes. Electrophysiologic examinations are widely recommended in diagnostics of LFHI, wheras up to now no data exist about the prognostic value of these examinations in a conservative therapeutic regimen. METHODS: In a quality assessment, we retrospectively evaluated the records of 90 patients, and performed an audiometric follow-up for analysis of long-time hearing data. All patients had undergone diagnostic electrocochleographic examination (ECochG) and then had been treated with rheologic infusions, followed by dehydrating infusions in patients lacking complete remission. The results of both therapeutic strategies and of long-time results were correlated to electrophysiologic findings. RESULTS: The prognosis of LFHI is significantly reflected by pretherapeutic electrocochleographic data. All significant parameters were associated to compound action potential (CAP) whereas parameters associated to cochlear microphonics (CM) did not include any utilizable prognostic value. In patients with a good outcome, the latency of CAP complex was significantly shorter, and the width of CAP complex significantly smaller than in patients with poor hearing outcome after rheologic and after dehydrating therapy and in long time assessment. The relation of summating potential (SP) und CAP was significantly smaller when the outcome was sufficient or good for either therapy and in long time analysis. Steep CAP-input-output-curves were associated to insufficient outcome after rheologic therapy and in long time assessment, but not for dehydrating therapy. CONCLUSIONS: The results indicate that ECochG is of significant prognostic value concerning hearing outcome after conservative therapy in patients suffering from LFHI. It can help the physician to counsel the patient and perform an effective management of the disease. We conclude that ECochG should be performed before the onset of therapy, including collection of SP and CAP data whereas CM parameters may be omitted. 相似文献
87.
Martine Visser Johan Marinus Jacobus J van Hilten Ruth G B Schipper Anne M Stiggelbout 《Movement disorders》2004,19(7):824-828
The aim of this study was to assess the accuracy of an interview-based assessment of comorbidity, in patients with Parkinson's disease (PD). The Cumulative Illness Rating Scale-Geriatric (CIRS-G) was completed (1) in an interview with 31 PD patients and their caregivers, and (2) by reviewing the patient's medical charts from their general practitioners. Based on the interview, all patients had some comorbidity, 84% had one or more moderate comorbid diseases. The most frequently affected organ systems were "lower gastrointestinal" and "genitourinary". The mean +/- SD total score of the interview-based (chart-based) CIRS-G was 6.9 +/- 3.8 (7.6 +/- 3.5) with a mean of 4.3 +/- 1.9 (5.0 +/- 1.9) affected organ systems and a mean of 2.1 +/- 1.7 (2.3 +/- 1.6) organ systems with at least moderate comorbidity per patient. The agreement (intraclass correlation coefficients) between the interview-based and chart-based assessments for the six summary scores ranged from 0.69 to 0.81. The agreement for the 14 organ systems ranged from 0.13 to 1.00 (weighted kappa); 12 had a K(w) above 0.40 (moderate agreement). The comorbidity summary scores had a moderate correlation with age and disability. The interview-based assessment of the CIRS-G is easy to apply and is an accurate method to assess comorbidity in patients with PD. 相似文献
88.
One of the main obstacles in pharmaceutical applications of cyclodextrins is their increase of the formulation bulk. Even at maximum incorporation 500 mg of a solid drug/cyclodextrin complex will only contain between 50 and 125 mg of the drug, assuming a low molecular weight drug (MW 200 to 400 Dalton) and an average molecular weight cyclodextrin (MW about 1500 Dalton). In general, the complexation efficiency is low and consequently the complex powder contains a significant amount of empty cyclodextrin molecules. In the present study the complexation efficiency is increased by ionization of the drug molecule through addition of volatile acid (i.e. acetic acid) or base (i.e. ammonia) to the aqueous complexation media of basic or acidic drugs, respectively. The volatile acid or base was then removed during lyophilization and heating in a vacuum oven resulting in formation of solid cyclodextrin complexes of the unionized drug. Thus, the complexation efficiency was temporary increased by the ionization but then again decreased leading to formation of the thermodynamically unstable solid drug/cyclodextrin complexes. When dissolved the energy of the system was lowered by expelling the drug molecules from the cyclodextrin cavities resulting in formation of supersaturated drug solutions and ultimately precipitation of the drug. 相似文献
89.
Besselink HT Schipper C Klamer H Leonards P Verhaar H Felzel E Murk AJ Thain J Hosoe K Schoeters G Legler J Brouwer B 《Environmental toxicology and chemistry / SETAC》2004,23(12):2781-2789
In the Fourth National Policy Document on Water Management in The Netherlands, it is defined that in 2003, in addition to the assessment of chemical substances, special guidelines for the assessment of dredged material should be recorded. The assessment of dredged material is based on integrated chemical and biological effect measurements. Among others, the DR CALUX (dioxin responsive-chemically activated luciferase expression) bioassay has tentatively been recommended for inclusion in the dredged material assessment. To ensure the reliability of this bioassay, an intra- and interlaboratory validation study, or ring test, was performed, organized by the Dutch National Institute for Coastal and Marine Management (RIKZ) in cooperation with BioDetection Systems BV (BDS). The intralaboratory repeatability and reproducibility and the limit of detection (LOD) and quantification (LOQ) of the DR CALUX bioassay were determined by analyzing sediment extracts and dimethyl sulfoxide (DMSO) blanks. The highest observed repeatability was found to be 24.1%, whereas the highest observed reproducibility was calculated to be 19.9%. Based on the obtained results, the LOD and LOQ to be applied for the bioassay are 0.3 and 1.0 pM, respectively. The interlaboratory calibration study was divided into three phases, starting with analyzing pure chemicals. During the second phase, sediment extracts were analyzed, whereas in the third phase, whole sediments had to be extracted, cleaned, and analyzed. The average interlaboratory repeatability increased from 14.6% for the analysis of pure compound to 26.1% for the analysis of whole matrix. A similar increase in reproducibility with increasing complexity of handlings was observed with the interlaboratory reproducibility of 6.5% for pure compound and 27.9% for whole matrix. The results of this study are intended as a starting point for implementing the integrated chemical-biological assessment strategy and for systematic monitoring of dredged materials and related materials in the coming years. 相似文献
90.