全文获取类型
收费全文 | 873篇 |
免费 | 59篇 |
国内免费 | 6篇 |
专业分类
耳鼻咽喉 | 8篇 |
儿科学 | 39篇 |
妇产科学 | 11篇 |
基础医学 | 114篇 |
口腔科学 | 12篇 |
临床医学 | 76篇 |
内科学 | 195篇 |
皮肤病学 | 16篇 |
神经病学 | 129篇 |
特种医学 | 9篇 |
外科学 | 95篇 |
综合类 | 1篇 |
预防医学 | 48篇 |
眼科学 | 5篇 |
药学 | 57篇 |
中国医学 | 2篇 |
肿瘤学 | 121篇 |
出版年
2023年 | 5篇 |
2022年 | 6篇 |
2021年 | 23篇 |
2020年 | 14篇 |
2019年 | 16篇 |
2018年 | 14篇 |
2017年 | 23篇 |
2016年 | 14篇 |
2015年 | 18篇 |
2014年 | 24篇 |
2013年 | 51篇 |
2012年 | 66篇 |
2011年 | 68篇 |
2010年 | 29篇 |
2009年 | 38篇 |
2008年 | 68篇 |
2007年 | 59篇 |
2006年 | 68篇 |
2005年 | 53篇 |
2004年 | 67篇 |
2003年 | 53篇 |
2002年 | 63篇 |
2001年 | 10篇 |
2000年 | 4篇 |
1999年 | 9篇 |
1998年 | 8篇 |
1997年 | 7篇 |
1996年 | 7篇 |
1995年 | 8篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有938条查询结果,搜索用时 15 毫秒
871.
S. Preston-Martin Janice M. Pogoda Beth A. Mueller Flora Lubin Baruch Modan Elizabeth A. Holly Graziella Filippini Sylvaine Cordier Raphael Peris-Bonet Won Choi Julian Little Annie Arslan 《Child's nervous system》1998,14(10):551-557
An international case-control study of primary pediatric brain tumors included interviews with mothers of cases diagnosed
from 1976–1994 and mothers of population controls. Data are available on maternal vitamin use during pregnancy for 1051 cases
and for 1919 controls in eight geographic areas of North America, Europe and Israel. While risk estimates varied by study
center, combined results suggest that maternal supplementation for two trimesters may decrease risk of brain tumor [odds ratio
(OR)=0.7; 95% confidence interval (CI)=0.5– 0.9], with a trend toward less risk with longer duration of use (P trend= 0.0007).
The greatest risk reduction was among children diagnosed under 5 years of age whose mothers used supplements during all three
trimesters (OR=0.5; CI=0.3– 0.8). This effect did not vary by histology and was seen for supplementation during pregnancy
rather than during the month before pregnancy or while breast feeding. These findings are largely driven by data from the
US, where most mothers took vitamins. The proportion of control mothers who took vitamins during pregnancy varied tremendously,
from 3% in Israel and in France through 21% in Italy, 33% in Canada, 52% in Spain to 86–92% at the three US centers. The composition
of the various multivitamin compounds taken also varied: daily dose of vitamin C ranged from 0 up to 600 mg; vitamin E from
0 to 70 mg; vitamin A from 0 to 30,000 IU and folate from 0 to 2000 mg. Mothers also took individual micronutrient supplements
(e.g., vitamin C tablets), but most mothers who took these also took multivitamins, making it impossible to determine potential
independent effects of these micronutrients.
Received: 15 May 1998 相似文献
872.
Comai S Costa CV Ragazzi E Bertazzo A Allegri G 《Clinica chimica acta; international journal of clinical chemistry》2005,360(1-2):67-80
BACKGROUND: Quinolinic acid and other kynurenine metabolites of the oxidative metabolism of tryptophan play an important role in several pathophysiological conditions. We aimed to study the effect of age on the enzyme activities of tryptophan metabolism along the kynurenine pathway. METHODS: Enzyme activity was investigated in liver, kidneys and small intestine obtained from Sprague-Dawley rats of various ages (1 week, 2-3, 12 and 18 months). RESULTS: We found age-related differences in the liver tryptophan 2,3-dioxygenase, small intestine indole 2,3-dioxygenase, liver and kidney kynurenine 3-monooxygenase activities, which decreased significantly with age. Also liver kynureninase activity declined with age, while the activity in kidneys did not show an evident age-related pattern from 2-3 months to 18 months of age. Liver kynurenine oxoglutarate transaminase was quite similar through all considered age groups, while the activity in kidneys was significantly lower in newborn rats and progressively increased up to 12 months, then significantly decreased at 18 months of age. Liver and kidney 3-hydroxyanthranilate 3,4-dioxygenase progressively and significantly increased from newborns to 12 months of age; in the group of rats aged 18 months, the enzyme activity tended to diminish, although not significantly. The liver aminocarboxymuconate-semialdehyde decarboxylase activity increased up to 12 months of age, then tended to decrease at 18 months, while in the kidneys, in which the activity was higher than in the liver at all the considered ages, the activity remained constantly elevated from 2-3 months to 18 months of age. CONCLUSIONS: A progressive decline in the enzyme activities involved in tryptophan metabolism along the kynurenine pathway in rat tissues was found with age, except for aminocarboxymuconate-semialdehyde decarboxylase, which, on the contrary, was increased after 2-3 months to the other older groups of age. The altered metabolism of tryptophan with ageing can lead to a decreased biosynthesis of nicotinic acid, tryptophan being the major source of body stores of NAD coenzymes, which are involved in almost all biogenetic and biosynthetic pathways of the organism. 相似文献
873.
Massimino M Gandola L Spreafico F Luksch R Collini P Giangaspero F Simonetti F Casanova M Cefalo G Pignoli E Ferrari A Terenziani M Podda M Meazza C Polastri D Poggi G Ravagnani F Fossati-Bellani F 《International journal of radiation oncology, biology, physics》2006,64(4):1031-1037
PURPOSE: Supratentorial primitive neuroectodermal tumors (S-PNET) are rare and have a grim prognosis, frequently taking an aggressive course with local relapse and metastatic spread. We report the results of a mono-institutional therapeutic trial. METHODS AND MATERIALS: We enrolled 15 consecutive patients to preradiation chemotherapy (CT) consisting of high-dose methotrexate, high-dose etoposide, high-dose cyclophosphamide, and high-dose carboplatin, craniospinal irradiation (CSI) with hyperfractionated accelerated radiotherapy (HART) plus focal boost, maintenance with vincristine/lomustine or consolidation with high-dose thiotepa followed by autologous stem-cell rescue. RESULTS: Median age was 9 years; 7 were male, 8 female. Site of disease was pineal in 3, elsewhere in 12. Six patients were had no evidence of disease after surgery (NED). Of those with evidence of disease after surgery (ED), 2 had central nervous system spread. Of the 9 ED patients, 2 had complete response (CR) and 2 partial response (PR) after CT, 4 stable disease, and 1 progressive disease. Of the 7 ED patients before radiotherapy, 1 had CR, 4 PR, and 2 minor response, thus obtaining a 44% CR + PR after CT and 71% after HART. Because of rapid progression in 2 of the first 5 patients, high-dose thiotepa was systematically adopted after HART in the subsequent 10 patients. Six of 15 patients relapsed (4 locally, 1 locally with dissemination, 1 with dissemination) a mean of 6 months after starting CT, 2 developed second tumors; 5 of 6 relapsers died at a median of 13 months. Three-year progression-free survival, event-free survival, and overall survival were 54%, 34%, and 61%, respectively. CONCLUSION: Hyperfractionated accelerated RT was the main tool in obtaining responses in S-PNET; introducing the myeloablative phase improved the prognosis (3/10 vs. 3/5 relapses), though the outcome remained unsatisfactory despite the adoption of this intensive treatment. 相似文献
874.
Simonetti O Goteri G Lucarini G Filosa A Pieramici T Rubini C Biagini G Offidani A 《European journal of cancer (Oxford, England : 1990)》2006,42(8):1181-1187
Aim of this study was to investigate using immunohistochemistry techniques the interrelation between T immunoreactive cells and the expression of CCR10 and its ligand CCL27 in 59 cutaneous melanocytic lesions. In malignant melanomas, T lymphocyte density was significantly decreased from thin melanomas to intermediate and thick ones (P<0.0005). CCR10 expression was found both in benign and malignant lesions and it was directly correlated with the Breslow depth (P=0.0298) and inversely with T lymphocyte density (P=0.0231). Moreover, cases with positive sentinel lymph node tended to have a higher CCR10 expression compared to cases with negative sentinel lymph node (P=0.0281). When CCR10 and CCL27 expression were evaluated together, CCR10-/CCL27-melanomas tended to have a higher mean density of CD3+ and CD8+ lymphocytes. Our results suggest that in human melanomas CCR10 and CCL27 may act to increase the ability of neoplastic cells to grow, invade tissue, disseminate to lymph nodes and to escape the host immune response. 相似文献
875.
Angiogenesis is a tightly regulated process, both during development and adult life. Animal models with mutations in the genes coding for placental growth factor (PlGF), a member of vascular endothelial growth factor (VEGF) family, or the tyrosine kinase domain of the PlGF receptor (Flt-1) have revealed differences between normal physiological angiogenesis and pathological angiogenesis associated with conditions such as tumor growth, arthritis and atherosclerosis. In the present paper, we investigated the potential role of PlGF in regulating physiological angiogenesis by analyzing vascular changes in heart and skeletal muscles of wild-type and Plgf–/– mice following prolonged and sustained physical training. Sedentary Plgf–/– mice showed a reduced capillary density in both heart and skeletal muscles as compared to wild-type mice (P < 0.05). However, after a 6-week training period, heart/body weight ratio, citrate synthase activity, vessel density and capillary/myocyte ratio were significantly increased in both wild-type and Plgf–/– mice (all P < 0.05). At the same time intercapillary distance was significantly reduced. Finally, acute exercise was not associated with any change in PlGF protein level in the skeletal muscle. Our results demonstrate that PlGF is not necessary for exercise-training-induced angiogenesis. We thus suggest that the role of PlGF is confined to the selective regulation of angiogenesis only under pathological conditions. 相似文献
876.
Carle F Gesuita R Bruno G Coppa GV Falorni A Lorini R Martinucci ME Pozzilli P Prisco F Songini M Tenconi MT Cherubini V;RIDI Study Group 《Diabetes care》2004,27(12):2790-2796
OBJECTIVE: The Registry for Type 1 Diabetes Mellitus in Italy (RIDI) Study Group was established to coordinate the registries of type 1 diabetes in Italy. This report is based on 3,606 children younger than 15 years diagnosed with type 1 diabetes and prospectively registered during 1990-1999 by nine centers, covering >35% of the Italian population. RESEARCH DESIGN AND METHODS: Registries were pooled in four geographic macro-areas: north, central, south, and insular. The completeness of registration was assessed by the capture-recapture method. Poisson regression analysis was used to evaluate temporal trend in incidence. RESULTS: Large variations in incidence were confirmed not only between Sardegna and the mainland but also among peninsular areas. In Sardegna, there was an excess of boys (the boy-to-girl incidence ratio was 1.4). The overall incidence showed average increases of 3.6% (P <0.001) and 3.7% (P <0.001) per year in peninsular Italy and in Sardegna, respectively. Significant increases in incidence rates were found in boys aged 10-14 years (6.7%, 95% CI 0.5-13.3) and in girls aged 5-9 years (6.6%, 0.5-13.1) living in the southern area. The incidence rate also increased in boys aged 10-14 years (5.0%, 0.3-10) and in girls aged 0-4 years (4.9%, 0.8-9.1) living in Sardegna. CONCLUSIONS: Italy is a country with large geographical variations in incidence rates of type 1 diabetes. However, the rates are evenly increasing both in the mainland and Sardegna, suggesting that similar environmental factors are operating over populations that have different genetic backgrounds. 相似文献
877.
Martone T Rosso P Albera R Migliaretti G Fraire F Pignataro L Pruneri G Bellone G Cortesina G 《Oral oncology》2005,41(2):147-155
Angiogenesis is essential for the development and progression of malignant tumours, and there is increasing evidence that microvessel density (MVD) can be considered an indirect marker of neo-angiogenesis. However, there is still disagreement concerning the clinical relevance and prognostic significance of MVD in head and neck squamous cell carcinomas (HNSCCs). MVD was evaluated in 127 HNSCC patients by means of immunohistochemistry using monoclonal antibodies (mAbs) against CD34 and CD105 (endoglin), which has recently been described as a potent marker of neo-vascularisation in various malignancies. MVD was expressed as the mean number of vessels/mm2. The mean CD34+ and CD105+ MVD values were significantly higher in T3-T4 tumours and those in an advanced clinical stage; furthermore, CD105+ MVD was significantly higher in N+ tumours. The patients with a high CD105+ MVD had a significantly shorter disease-free and overall survival; CD34+ MVD was not associated with survival. Similarly, in the subset of lymph-node negative patients, higher CD105+ MVD values were significantly associated with either OS and DFS. Multivariate analysis showed that a high CD105+ MVD was the only independent marker of tumour recurrence or death. Our data suggest that CD105+ MVD may represent an additional prognostic factor in HNSCC patients providing more accurate data for the determination of prognosis and management in the subset of lymph node negative patients. 相似文献
878.
Privitera O Vessecchia G Bernasconi B Bettio D Stioui S Giordano G 《Prenatal diagnosis》2005,25(10):945-948
BACKGROUND: We report on a fetus with sex reversal and del(9)(p24) consequent to a malsegregation of a maternal balanced complex translocation involving chromosomes 7, 9 and 11. METHODS: Fluorescence in situ hybridization (FISH) was performed in order to verify the presence of the SRY gene and the absence of DMRT1 and DMRT2 genes located in 9p24.3 region and frequently associated with sex reversal. RESULTS AND CONCLUSIONS: The prenatal karyotype revealed an unbalanced male fetus. The postmortem examination showed a malformed fetus with female external genitalia. Lack of DMRT1-2 genes established by FISH. 相似文献
879.
880.
A new series of 3-phenyl-1-(1,1'-biphenyl-4-yl)-2-(1H-imidazol-1-yl)propane derivatives 2a-l (related to the antifungal bifonazole) was synthesized and tested for antimicrobial activity. A number of substituents on the phenyl ring were chosen to compare the relative biological properties with those of corresponding aza-analogues, previously described by us. The in vitro antifungal activities of the newly synthesized azoles were tested against several pathogenic fungi responsible for human disease. Test pathogens included representatives of yeasts (Candida albicans, Candida parapsilosis, Criptococcus neoformans), dermathophytes (Tricophyton verrucosum, Tricophyton rubrum, Microsporum gypseum) and moulds (Aspergillus fumigatus). Bifonazole and miconazole were used as reference drugs. Title compounds were prepared by alkylation of 1-biphenyl-4-yl-2-imidazol-1-yl-ethanone with the proper arylmethyl halide and subsequent reduction of corresponding ketones applying the Huang-Minlon modification of the Wolff-Kishner reaction. 相似文献