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   17364篇
  免费   922篇
  国内免费   65篇
耳鼻咽喉   235篇
儿科学   453篇
妇产科学   340篇
基础医学   2482篇
口腔科学   299篇
临床医学   1558篇
内科学   3462篇
皮肤病学   520篇
神经病学   2166篇
特种医学   993篇
外科学   2341篇
综合类   125篇
一般理论   4篇
预防医学   872篇
眼科学   288篇
药学   949篇
中国医学   62篇
肿瘤学   1202篇
  2023年   149篇
  2022年   244篇
  2021年   438篇
  2020年   294篇
  2019年   415篇
  2018年   447篇
  2017年   404篇
  2016年   499篇
  2015年   495篇
  2014年   687篇
  2013年   821篇
  2012年   1328篇
  2011年   1400篇
  2010年   805篇
  2009年   702篇
  2008年   1162篇
  2007年   1145篇
  2006年   1091篇
  2005年   1082篇
  2004年   923篇
  2003年   876篇
  2002年   788篇
  2001年   148篇
  2000年   120篇
  1999年   165篇
  1998年   185篇
  1997年   134篇
  1996年   134篇
  1995年   89篇
  1994年   91篇
  1993年   62篇
  1992年   47篇
  1991年   51篇
  1990年   37篇
  1989年   28篇
  1988年   29篇
  1987年   30篇
  1986年   24篇
  1985年   28篇
  1984年   23篇
  1983年   22篇
  1982年   30篇
  1981年   23篇
  1980年   36篇
  1979年   24篇
  1978年   21篇
  1977年   31篇
  1976年   18篇
  1936年   15篇
  1933年   15篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Summary The operative correction of the pathological flat acetabulum in congenital dislocation of the hip, myelodysplasia and cerebral palsy can be performed with pelvic osteotomies and acetabuloplasties. In the light of our own experiences gained with different methods we prefer the pericapsular osteotomy of the ilium according to Pemberton since 1971. After the evaluation of the results the advantages of the method compared with other procedures are presented in the light of the improvements of correction and the rate of complication.
Zusammenfassung Die operative Korrektur der Flachpfannen bei Luxationshüfte, Myelodysplasie und Zerebralparese kann mittels Beckenosteotomie oder Azetabuloplastik erzielt werden. Anhand eigener Erfahrungen mit verschiedenen Methoden wird seit 1971 die perikapsuläre Iliumosteotomie nach Pemberton bevorzugt. Nach Auswertung der Ergebnisse werden die Vorteile der Methode gegenüber den anderen Verfahren anhand des Korrekturgewinnes und der Komplikationsrate dargelegt.
  相似文献   
102.
Summary Oral MPA 1.5 g/day leads to plasma concentrations between 1 and 12 g/ml, with a broad intra-and interindividual variance. The plateau state is reached in between 4 and 16 days. Plasma concentrations in the plateau state are very sensitive to dose modifications. After cessation of administration, the decline in plasma levels seems to proceed in two phases, with half-times of about 20 h and 4 days. Extraction procedures reveal no benefit in discriminating between MPA and its metabolites.  相似文献   
103.
Steady-state kinetics of imipramine in patients   总被引:1,自引:0,他引:1  
Steady-state plasma level kinetics were studied in 76 patients given imipramine (IP) 150 to 225 mg/day for 2–5 weeks. IP was given in three divided doses at 8.00 a.m., 1.00 p.m. and 5.00 p.m. Plasma concentrations of IP and its active metabolite desipramine (DMI) were determined by quantitative in situ thin-layer chromatography. The plasma levels of IP and DMI showed pronounced flucutations throughout the day with a ratio of about 2 between highest and lowest level. Patients with steady-state levels of IP and/or DMI below 50 g/l reached this within 1 week of treatment. Patients with higher steady-state levels reached steady-state concentrations within 2–3 weeks. There were some intraindividual fluctuations in plasma levels from week to week after steady state had been reached (coefficient of variation: 10–20%). Interindividually, the steady-state levels corrected to a dose of 3.5 mg/kg per day varied considerably: IP: 6–356 g/l, DMI: 24–659 g/l and IP+DMI: 58–809 g/l. The steady-state plasma levels showed a skew distribution that became normal by logarithmic transformation. The IP/DMI ratio ranged from 0.07 to 5.5 with a median value of 0.47. Compared to data from amitriptyline treated patients the IP/DMI ratios had significantly lower median value and larger variation than the corresponding plasma level ratios of amitriptyline/nortriptyline. Several statistically significant differences in steady-state levels between age groups were found. For IP: Women aged 30–39 had lower levels than women aged 20–29, 40–49, and 50–59, and men aged 50–59 and 60–65; men aged 30–39 had lower levels than men aged 60–65. For DMI: Women aged 30–39 had lower levels than women aged 50–59.  相似文献   
104.
Long-term exposure of rodents to propylene oxide (PO) induced inflammation, respiratory cell hyperplasia, and nasal tumors at concentrations >/= 300 ppm, suggesting a possible role for cytotoxicity and compensatory cell proliferation in PO carcinogenesis. In this study, the effects of PO exposure on histopathology and cell proliferation in nasal and hepatic tissues were studied in male F344 rats exposed by inhalation for 3 or 20 days (0, 5, 25, 50, 300, and 500 ppm). Histopathology revealed an increase in mucous cell hyperplasia in the anterior nasal passages after 20 days of exposure (>/=300 ppm). This was associated with the formation of goblet cell nests. Cell proliferation was measured in the respiratory epithelium (NRE; mucociliary and transitional) lining the anterior nasal passages, the nasopharyngeal meatus (NPM), and the liver using BrdU administered with 3-day osmotic pumps. Significant increases in cell proliferation occurred (>3.6-fold) in the mucociliary epithelium lining the anterior nasal cavity at and above 300 ppm for both exposure periods. In the mucociliary epithelium, the 20-day labeling was commonly associated with nests of goblet cells. Significant increases in cell proliferation (>2.3-fold) were observed in the transitional epithelium at 500 ppm after 3 days of exposure and at 300 and 500 ppm after 20 days of exposure. Significant increases in cell proliferation in the NPM (>2.8-fold) were evident at 500 ppm PO after 3 days and at 300 and 500 ppm PO after 20 days of exposure. No exposure-related changes in cell proliferation were observed in the liver. These studies demonstrate a clear concordance between the site and exposure concentration for tumor induction and those causing significant increases in cell proliferation in the rat nose.  相似文献   
105.
PURPOSE: Methyl-[11C]L-methionine ([11C]MET) positron emission tomography (PET) in brain tumors reflects amino acid transport and has been shown to be more sensitive than magnetic resonance imaging in stereotactic biopsy planning. It remains unclear whether the increased [11C]MET uptake is limited to solid tumor tissue or even detects infiltrating tumor parts. EXPERIMENTAL DESIGN: In 30 patients, a primary or recurrent brain tumor was suspected on magnetic resonance imaging. Patients were investigated with [11C]MET-PET before stereotactic biopsy. The biopsy trajectories were plotted into the [11C]MET-PET images with a newly designed C-based software program. The exact local [11C]MET uptake was determined within rectangular regions of interest of 4 mm in width and length aligned with the biopsy specimen. Individual histologic specimens were rated for the presence of solid tumor tissue, infiltration area, and nontumorous tissue changes. RESULTS: Receiver operating characteristics analysis demonstrated a sensitivity of 87% and specificity of 89% for the detection of tumor tissue at a threshold of 1.3-fold [11C]MET uptake relative to normal brain tissue. At this threshold, only 13 of 100 tumor positive specimen were false negative mainly in grade 2 astrocytoma. In grade 2 astrocytoma, mean [11C]MET uptake in the infiltration area was significantly higher than in solid tumor tissue (P < 0.003). CONCLUSIONS: [11C]MET-PET detects solid parts of brain tumors, as well as the infiltration area at high sensitivity and specificity. High [11C]MET uptake in infiltrating tumor of astrocytoma WHO grade 2 reflects high activity in this tumor compartment. Molecular imaging, with [11C]MET, will guide improved management of patients with brain tumors.  相似文献   
106.
107.
BACKGROUND AND PURPOSE: Interstitial implants for brachytherapy boost in the breast conserving therapy of breast cancer can be performed in two ways; implants during the tumor excision (per-operative implants) or after the external beam therapy (delayed interstitial implants). Differences in cosmetic outcome were investigated. PATIENTS AND METHODS: Cosmetic results in 47 patients having a per-operative implant were compared to 123 patients having a delayed interstitial implant in a matched case-control study. Cosmesis was scored on a four-point-scale varying from 0 (excellent) to 3 (poor). RESULTS: After mean follow-up of 63 months, three observers found no difference in cosmetic outcome between the two groups after adjustment for variables found to be related with cosmesis (difference in mean score 0.50, P=0.26). Implant volume at 100% isodose was not found to differ (P=0.084) between the per-operative group (mean 102 cm3, S.D. 34 cm3) and the delayed group (mean 93 cm3, S.D. 29 cm3). CONCLUSIONS: Performing per-operative implants has not led to smaller implants. The method of performing brachytherapy does not result in marked differences in cosmetic outcome.  相似文献   
108.
PURPOSE: With limited response rates and potential toxicity of chemotherapeutic treatment in patients with recurrent glioma, reliable response assessment is essential. Currently, the assessment of treatment response in glioma patients is based on the combination of radiologic and clinical findings. However, response monitoring with computed tomography (CT) or magnetic resonance imaging (MRI) is hampered by several pitfalls and is prone to interobserver variability. The aim of this study was to establish the value of thallium-201 single-photon emission computed tomography (201Tl-SPECT) as a predictor of overall survival and response to chemotherapy in recurrent glioma, and to compare the value of 201Tl-SPECT with that of CT and MRI. PATIENTS AND METHODS: We studied patients who underwent CT or MRI and 201Tl-SPECT before chemotherapy (n = 57), and patients who also had undergone CT or MRI and 201Tl-SPECT after two courses of chemotherapy (n = 44). The value of the radiologic variables (CT-MRI tumor size, 201Tl-SPECT tumor size, and maximal tumor intensity) at baseline and at follow-up in predicting overall survival, and the percentage of patients alive and progression-free at 6 months (APF6) were examined using Cox regression and logistic regression analysis. RESULTS: Both at baseline and at follow-up, 201Tl-SPECT maximal tumor intensity was the strongest predictive variable and was inversely related to overall survival and APF6. In particular, progression of maximal tumor intensity after two courses of chemotherapy was a powerful predictor of poor outcome. CONCLUSION: 201Tl-SPECT is superior to conventional CT-MRI in the early prediction of overall survival and response to chemotherapy in patients with recurrent glioma.  相似文献   
109.
A systematic assessment of radiotherapy for cancer was conducted by The Swedish Council on Technology Assessment in Health Care (SBU) and published in 1996. The assessment reviewed the scientific literature up to 1993 on the use of radiotherapy in the treatment of solid tumours, and estimated the costs associated with radiotherapy. It also described the current practise of radiotherapy in Sweden 1992 and compared practise with scientific knowledge. The SBU has now conducted a follow-up study on radiotherapy for cancer, including a review of the scientific literature from 1994 and a prospective survey of radiotherapy practise in Sweden 2001. The following conclusions were drawn: The role of radiotherapy as an important form of treatment for cancer with both curative and palliative intent has been further confirmed.The use of radiotherapy in Sweden has increased and is now at the internationally recommended level.Radiotherapy in Sweden is mostly given in accordance with the scientific evidence but may still be underutilized in certain situations.The resources for radiotherapy are being utilized more efficiently.The costs of radiotherapy are still 5% of the total cost of cancer care, while the cost of an individual treatment (fraction) has decreased.The need for radiotherapy capacity will increase. In addition, half of the treatment equipment will have to be replaced in the next few years.  相似文献   
110.
PURPOSE: This phase II clinical study evaluated the efficacy of pemetrexed for the treatment of malignant pleural mesothelioma (MPM). PATIENTS AND METHODS: Patients with a histologically proven diagnosis of MPM, chemotherapy-naive measurable lesions, and adequate organ function received pemetrexed (500 mg/m2) intravenously over 10 minutes every 3 weeks. After a protocol change, most patients also received folic acid and vitamin B12 supplementation to improve safety. RESULTS: A total of 64 patients were enrolled. Nine (14.1%) of the 64 patients had a partial response. The Kaplan-Meier estimate for median overall survival was 10.7 months. Forty-three patients received vitamin supplementation for all courses of therapy, and 21 patients did not. Seven of the nine responders were vitamin supplemented. The median overall survival was 13.0 months for supplemented patients and 8.0 months for nonsupplemented patients. Vitamin-supplemented patients completed more cycles of therapy than nonsupplemented patients (median, six v two cycles, respectively). Grade 3/4 neutropenia (23.4%) and grade 3/4 leukopenia (18.8%) were the most common laboratory toxicities. Fatigue and febrile neutropenia were the most commonly reported nonlaboratory events (grade 3, 6.3%; grade 4, 0.0% each). The incidence of these toxicities was generally lower in the supplemented patients. CONCLUSION: Single-agent pemetrexed for MPM resulted in a moderate response rate (14.1%) and median overall survival of 10.7 months. Patients supplemented with folic acid and vitamin B12 tolerated treatment better (less toxicity and more cycles of treatment) and had a 5-month greater median overall survival than nonsupplemented patients. These results indicate that patients with MPM could benefit from single-agent pemetrexed treatment combined with vitamin supplementation.  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