全文获取类型
收费全文 | 116890篇 |
免费 | 5979篇 |
国内免费 | 139篇 |
专业分类
耳鼻咽喉 | 1775篇 |
儿科学 | 5243篇 |
妇产科学 | 3936篇 |
基础医学 | 16216篇 |
口腔科学 | 2838篇 |
临床医学 | 8378篇 |
内科学 | 22151篇 |
皮肤病学 | 3371篇 |
神经病学 | 9062篇 |
特种医学 | 5121篇 |
外国民族医学 | 32篇 |
外科学 | 19089篇 |
综合类 | 1603篇 |
一般理论 | 29篇 |
预防医学 | 5946篇 |
眼科学 | 3396篇 |
药学 | 8104篇 |
中国医学 | 326篇 |
肿瘤学 | 6392篇 |
出版年
2018年 | 906篇 |
2017年 | 795篇 |
2016年 | 1118篇 |
2015年 | 1248篇 |
2014年 | 1632篇 |
2013年 | 2385篇 |
2012年 | 3133篇 |
2011年 | 3181篇 |
2010年 | 1999篇 |
2009年 | 1945篇 |
2008年 | 3292篇 |
2007年 | 3518篇 |
2006年 | 3661篇 |
2005年 | 3771篇 |
2004年 | 3718篇 |
2003年 | 3590篇 |
2002年 | 3534篇 |
2001年 | 7044篇 |
2000年 | 6981篇 |
1999年 | 5880篇 |
1998年 | 1629篇 |
1997年 | 1573篇 |
1996年 | 1339篇 |
1995年 | 1207篇 |
1994年 | 1099篇 |
1993年 | 1125篇 |
1992年 | 3786篇 |
1991年 | 3593篇 |
1990年 | 3570篇 |
1989年 | 3363篇 |
1988年 | 3005篇 |
1987年 | 2901篇 |
1986年 | 2817篇 |
1985年 | 2623篇 |
1984年 | 1958篇 |
1983年 | 1607篇 |
1982年 | 933篇 |
1981年 | 923篇 |
1980年 | 766篇 |
1979年 | 1832篇 |
1978年 | 1351篇 |
1977年 | 1115篇 |
1976年 | 937篇 |
1975年 | 1183篇 |
1974年 | 1217篇 |
1973年 | 1199篇 |
1972年 | 1047篇 |
1971年 | 980篇 |
1970年 | 885篇 |
1969年 | 791篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
S L Gardini U Sergiacomi G G Colarossi 《Quaderni Sclavo di diagnostica clinica e di laboratorio》1987,23(1):32-42
New parametric and non parametric statistical methods have been compared in the evaluation of experimental data of CEA and CA 19.9 using a brief program in BASIC. We have found that the distribution of the two markers is the same of that described in literature except for both the means that we have found being slightly higher than that ones described by other authors. 相似文献
32.
A new rapid procedure for desiccating frozen resin-cracked retinal tissue for scanning electron microscopy (SEM) which permits air-drying was found to compare favorably with tissues prepared by critical-point drying: Retinal tissue was fixed in 4% phosphate-buffered neutral formaldehyde, dehydrated by means of graded ethanol, embedded in Epon, cracked and washed in propylene oxide. For desiccation, the specimens were immersed in hexamethyldisilazane (HMDS), air-dried and finally sputter-coated. The method is time-saving, gives extended information in SEM, and the number of good specimens is increased. 相似文献
33.
P Helwig G Faust U Hindenlang B Kr?plin C Eingartner 《Technology and health care》2006,14(4-5):411-419
Static analysis with finite element of a realistic femur nail bone-implant system in a typical proximal femoral fracture under physiological load bearing situations provides results for stress, displacement and strain. The question to be answered is, if simulation with the finite element analysis is able to explain biomechanically clinical observed patterns of failure. Surface-Reconstruction with CT database of a proximal femur and reconstruction with CT based density data was done. Next steps were to unite the bone structure with the Proximal Femoral Nail and to model two relevant fractures (31-A2.2 and A2.3 according AO). After modelling of geometry, isotropic material behaviour and load application numeric calculation of the femur-nail system with FE-software was performed. FE simulation mainly shows an axial dislocation of the femoral head screw with nearly no dislocation of the antirotation screw. This so-called z-effect therefore means: (1) Tilting of the proximal main fragment around the sagittal axis between the screws and (2) relative movement of both screws in the frontal plane. Relative movement of the two screws against each other could be the reason for implant failure, the so called cut out. Furthermore simulation shows different gliding of the screws explaining the so called z-telescoping. The analyzed stress patterns have to be relativized, because isotropic material behaviour of cancellous bone was assumed. Further examinations for this issue are necessary. 相似文献
34.
U I Esen 《Ultrasound in obstetrics & gynecology》2005,26(2):201; author reply 201-201; author reply 202
35.
36.
C. J. M. Antens M. Oldenwening A. Wolse U. Gehring H. A. Smit R. C. Aalberse M. Kerkhof J. Gerritsen J. C. de Jongste B. Brunekreef 《Clinical and experimental allergy》2006,36(12):1525-1531
BACKGROUND: Studies of the association between indoor allergen exposure and the development of allergic diseases have often measured allergen exposure at one point in time. OBJECTIVE: We investigated the variability of house dust mite (Der p 1, Der f 1) and cat (Fel d 1) allergen in Dutch homes over a period of 8 years. METHODS: Data were obtained in the Dutch PIAMA birth cohort study. Dust from the child's mattress, the parents' mattress and the living room floor was collected at four points in time, when the child was 3 months, 4, 6 and 8 years old. Dust samples were analysed for Der p 1, Der f 1 and Fel d 1 by sandwich enzyme immuno assay. RESULTS: Mite allergen concentrations for the child's mattress, the parents' mattress and the living room floor were moderately correlated between time-points. Agreement was better for cat allergen. For Der p 1 and Der f 1 on the child's mattress, the within-home variance was close to or smaller than the between-home variance in most cases. For Fel d 1, the within-home variance was almost always smaller than the between-home variance. Results were similar for allergen levels expressed per gram of dust and allergen levels expressed per square metre of the sampled surface. Variance ratios were smaller when samples were taken at shorter time intervals than at longer time intervals. CONCLUSION: Over a period of 4 years, mite and cat allergens measured in house dust are sufficiently stable to use single measurements with confidence in epidemiological studies. The within-home variance was larger when samples were taken 8 years apart so that over such long periods, repetition of sampling is recommended. 相似文献
37.
U Caliceti A Rinaldi Ceroni G Lisignoli P Chieco O Cavicchi 《Archives of oto-rhino-laryngology》1989,246(5):365-367
A microfluorometric method was used to determine the nuclear DNA content in the nasopharyngeal carcinomas (NPC) of 25 patients treated before 1983. Eleven patients are still alive with no evidence of disease (NED), while the rest died of their disease (DOD). All of the patients received a cycle of radiotherapy, while some also received chemotherapy or neck dissections. The neoplastic cells studied were taken from the original biopsy blocks, deparaffinized, isolated by enzymatic treatment and mechanical fragmentation, and then Feulgen-stained. The cytofluorometric measurement was carried out by a microphotometer equipped for fluorescence excitation and connected to a computer. This method allowed us to construct a histogram of the DNA content in the neoplastic cells. Different neoplastic classes were identified and represent the heteroclonality of the tumor, which can be expressed by the heteroclonality index (HCT). From the collected data it appears that the NED patients all had a low HTC (less than 1) and only 7 of the DOD patients had low HTCs (less than 1). Six of the DOD patients with a low HTC were in advanced stages of their tumor at the time of diagnosis, while the remaining patient did not complete his treatment. Our results show that the DNA analysis of the NPC cell population may offer a useful tool in predicting the biological behavior of this tumor and also improving its treatment. 相似文献
38.
Platelet Aggregation Inhibiting and Anticoagulant Effects of Oligoamines, VII: Benzene-1,3,5-trialkanamines Seventeen title compounds were synthesized. Platelet aggregation induced by collagen in vitro is inhibited by 9 of them at IC50 = 2–4 μmol/L. Seven compounds depress the formation of fibrin to ≦ 25 % of normal in concentrations below 50 μmol/L. Compound 15 [4-(2-thienylbutyl)benzene-1,3,5-trimethanamine is the first oligoamine which shows anticoagulant and antiplatelet effects at the same concentration (25 μmol/L). 相似文献
39.
Phenytoin-induced gingival overgrowth is a recognized side effect in many cerebral palsy patients using diphenyl hydantoin for the control of seizures. Severe gingival overgrowth in these patients can affect normal masticatory function, lead to poor occlusal development, and compromise esthetics. This report addresses the complex nature of treating phenytoin-induced gingival overgrowth in a mentally retarded 20-year-old female patient. For this patient, full-mouth gingivectomy procedure was performed under general anesthesia in a single session. Post operative follow-up was uneventful. This article discusses major indications, contraindications, and protocols to be followed for periodontal surgical procedures done under general anesthesia. 相似文献
40.
PD Dr. U. Germer 《Der Gyn?kologe》2005,38(6):553-554
Ohne Zusammenfassung 相似文献