全文获取类型
收费全文 | 1745篇 |
免费 | 120篇 |
国内免费 | 48篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 64篇 |
妇产科学 | 38篇 |
基础医学 | 256篇 |
口腔科学 | 13篇 |
临床医学 | 226篇 |
内科学 | 374篇 |
皮肤病学 | 26篇 |
神经病学 | 106篇 |
特种医学 | 303篇 |
外科学 | 146篇 |
综合类 | 25篇 |
一般理论 | 1篇 |
预防医学 | 100篇 |
眼科学 | 17篇 |
药学 | 124篇 |
中国医学 | 4篇 |
肿瘤学 | 86篇 |
出版年
2023年 | 13篇 |
2022年 | 12篇 |
2021年 | 19篇 |
2020年 | 22篇 |
2019年 | 18篇 |
2018年 | 27篇 |
2017年 | 39篇 |
2016年 | 36篇 |
2015年 | 64篇 |
2014年 | 43篇 |
2013年 | 71篇 |
2012年 | 97篇 |
2011年 | 84篇 |
2010年 | 85篇 |
2009年 | 82篇 |
2008年 | 78篇 |
2007年 | 118篇 |
2006年 | 83篇 |
2005年 | 81篇 |
2004年 | 79篇 |
2003年 | 63篇 |
2002年 | 69篇 |
2001年 | 22篇 |
2000年 | 13篇 |
1999年 | 13篇 |
1998年 | 56篇 |
1997年 | 59篇 |
1996年 | 63篇 |
1995年 | 31篇 |
1994年 | 38篇 |
1993年 | 26篇 |
1992年 | 10篇 |
1991年 | 15篇 |
1990年 | 11篇 |
1989年 | 39篇 |
1988年 | 28篇 |
1987年 | 25篇 |
1986年 | 23篇 |
1985年 | 15篇 |
1984年 | 19篇 |
1983年 | 10篇 |
1982年 | 23篇 |
1981年 | 17篇 |
1980年 | 16篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1975年 | 8篇 |
1933年 | 7篇 |
1932年 | 5篇 |
排序方式: 共有1913条查询结果,搜索用时 15 毫秒
1.
HJ Aubin S Tilikete C Laureaux HT Nguyen Hac MC Roullet-Volmi S Troupel D Barrucand 《European psychiatry》1995,10(8)
The aim of this study was to assess alcoholic inpatients' smoking and coffee intake variation following withdrawal. Only moderate smokers (less than 30 cigarettes/day) showed a significant increase of cigarette consumption after alcohol withdrawal. However, their urinary cotinine level did not vary, suggesting a behavioral, and not biological, compensation through smoking following alcohol withdrawal. Heavy smokers (30 cigarettes/day or more) showed no significant clinical or biological variation of smoking behavior. Coffee consumption increased after alcohol withdrawal in all patients, irrespective of smoking habits. 相似文献
2.
Florian Wiesinger Peter Boesiger Klaas P Pruessmann 《Magnetic resonance in medicine》2004,52(2):376-390
The purpose of this article is to elucidate inherent limitations to the performance of parallel MRI. The study focuses on the ultimate signal-to-noise ratio (SNR), which refers to the maximum SNR permitted by the electrodynamics of the signal detection process. Using a spherical model object, it is shown that the behavior of the ultimate SNR imposes distinct limits on the acceleration rate in parallel imaging. For low and moderate acceleration, the ultimate SNR performance is nearly optimal, with geometry factors close to 1. However, for high reduction factors beyond a critical value, the ultimate performance deteriorates rapidly, corresponding to exponential growth of the geometry factor. The transition from optimal to deteriorating performance depends on the electrodynamic characteristics of the detected RF fields. In the near-field regime, i.e., for low B0 and small object size, the critical reduction factor is constant and approximately equal to four for 1D acceleration in the sphere. In the far-field wave regime the critical reduction factor is larger and increases both with B0 and object size. Therefore, it is concluded that parallel techniques hold particular promise for human MR imaging at very high field. 相似文献
3.
S H A J Tytgat D M Laman A M Rijken R Klicks A Voorwinde J M Ultee H Van Duijn 《European journal of vascular and endovascular surgery》2005,29(2):156-161
PURPOSE: To investigate whether a single pre-operative dose of 120 mg acetylsalicylic acid (ASA) decreased either (1) emboli rate, as detected by transcranial Doppler (TCD), during and early after carotid endarterectomy (CEA) and (2) clinical intra- and post-operative signs suggestive of embolism or increased bleeding tendency. DESIGN: Prospective, double-blind placebo controlled trial. PATIENTS AND METHODS: One-hundred consecutive patients were randomised to receive either 120 mg ASA (n = 48) or placebo (n = 49) by suppository on the night before CEA; three patients were excluded. Emboli were counted and expressed as emboli rate (ER). The incidence of bleeding complications was assessed. Surgeons were asked to indicate which patients had received ASA or placebo. RESULTS: There were no significant differences between the ASA and placebo groups in ER in the intraoperative and postoperative periods. ER higher than 0.9 min(-1) was associated with a significantly increased risk of complications (26 vs. 0%, P < 0.01). No extra bleeding complications were observed in the ASA group. Surgeon assessment of whether or not ASA had been administered had a sensitivity of 42% and a specificity of 70%. CONCLUSION: A single pre-operative dose of ASA (120 mg) did not reduce significantly the emboli rate during and after CEA and surgeons could not correctly identify whether or not ASA had been administered. 相似文献
4.
BACKGROUND: A simple, rapid, inexpensive method for measuring the flow in a
patient's vascular access would permit routine monitoring during
haemodialysis, and hence provide information of access graft deterioration
sufficiently early to increase the success of minimally invasive remedial
procedures. This paper reports the validation of such a method in animals.
METHODS: A PTFE graft was implanted in sheep between the carotid artery and
the jugular vein. While the sheep was under general anaesthesia and on an
haemodialysis circuit, ultrasound velocity in its blood was perturbed by
the injection of a 5-10 ml bolus of isotonic NaCl. The pump tubing flow was
measured by a transit-time blood flow meter. This flow was combined with
the areas of perturbation generated by the injection before and after
mixing in the access flow to estimate graft flow. The calculated graft flow
was compared to flow measured directly by a transit-time probe on the same
carotid artery. RESULTS: Over a 10-fold range, 120-1260 ml/min, graft flow
measured by ultrasound velocity dilution agreed well with graft flow
measured directly with a scatter of 76 ml/min about the regression line.
CONCLUSION: Ultrasound velocity dilution provides a method for measuring
flow in the graft accurate enough for clinical evaluation of patients on
dialysis.
相似文献
5.
6.
Martin Buehrer Klaas P Pruessmann Peter Boesiger Sebastian Kozerke 《Magnetic resonance in medicine》2007,57(6):1131-1139
Arrays with large numbers of independent coil elements are becoming increasingly available as they provide increased signal-to-noise ratios (SNRs) and improved parallel imaging performance. Processing of data from a large set of independent receive channels is, however, associated with an increased memory and computational load in reconstruction. This work addresses this problem by introducing coil array compression. The method allows one to reduce the number of datasets from independent channels by combining all or partial sets in the time domain prior to image reconstruction. It is demonstrated that array compression can be very effective depending on the size of the region of interest (ROI). Based on 2D in vivo data obtained with a 32-element phased-array coil in the heart, it is shown that the number of channels can be compressed to as few as four with only 0.3% SNR loss in an ROI encompassing the heart. With twofold parallel imaging, only a 2% loss in SNR occurred using the same compression factor. 相似文献
7.
Werner I Hagens Peter Olinga Dirk K F Meijer Geny M M Groothuis Leonie Beljaars Klaas Poelstra 《Liver international》2006,26(2):232-239
BACKGROUND: Liver fibrosis is the common response to chronic liver injury, ultimately leading to cirrhosis. Several lines of evidence indicate that inducing apoptosis of hepatic stellate cells (HSC) may lead to regression of liver fibrosis. Recently, it was shown that gliotoxin (GTX) induces apoptosis of HSC. However, the clinical use of GTX may be limited because of the lack of cell and tissue specificity, causing a high risk of potentially severe adverse effects. The aim of this study, therefore, was to study the effect of GTX on different cells of the liver. METHODS: We used normal and fibrotic precision-cut rat liver slices to study the effect of GTX on the various resident liver cell types. In these slices, the complex cell-cell interactions are preserved, which closely mimics the in vivo situation. RESULTS: GTX exhibited a potent apoptosis-inducing activity in these slices. Both immunohistochemical stainings and real-time mRNA techniques showed that this apoptosis-inducing effect was seen in HSC. However, Kupffer cells and liver endothelial cells were also affected by GTX, whereas hepatocytes were only mildly affected. CONCLUSIONS: This study indicates that the apoptosis-inducing strategy to treat liver fibrosis has high potential, but it will be necessary to develop an HSC-specific therapy to prevent adverse effects. 相似文献
8.
M Kaplan HJ Vreman C Hammerman C Leiter B Rudensky MG MacDonald DK Stevenson 《Acta paediatrica (Oslo, Norway : 1992)》1998,87(4):455-457
The incidence (%) of hyperbilirubinemia (serum bilirubin ≥257 μmol/l) was similar in neonates with a combination of ABO incompatibility and glucose-6-phosphate dehydrogenase (G-6-PD) deficiency (45%), with ABO incompatibility (54%) or G-6-PD deficiency (37%), alone (ns). Carboxyhemoglobin values, corrected for inspired CO, were similarly elevated in all three groups (0.87 ± 0.32%, 0.82 ± 0.29%, 0.76 ± 0.18%, respectively, ns), but correlated with bilirubin only in those with ABO incompatibility alone. ABO-incompatible/G-6-PD-deficient neonates, compared with those with either condition alone, are not at increased risk for hemolysis or hyperbilirubinemia. 相似文献
9.
Attitudes toward male fertility control: results of a multinational survey on four continents 总被引:3,自引:0,他引:3
Heinemann K Saad F Wiesemes M White S Heinemann L 《Human reproduction (Oxford, England)》2005,20(2):549-556
BACKGROUND: Following extensive research activity to develop an effective agent to control male fertility, such a product may be available for use within approximately 5 years. However, little is known concerning contraceptive knowledge, desires and attitudes of men in different countries, and their acceptance of male fertility control (MFC). METHODS: A survey of >9000 males aged 18-50 years was performed in nine countries on four continents in 2002. The objective was to compare, on a cross-cultural basis, the knowledge, attitudes and acceptability of MFC among men and assess their willingness to use such a method. RESULTS: Between 50 and 83% of the male respondents currently use contraceptive methods, and 55-81.5% reported that both partners participate in selecting the method of contraception employed. Overall acceptance of hormonal MFC was high (>55%), with 28.5-71.4% of survey participants of various nationalities expressing the willingness to use such a method. CONCLUSION: While MFC appears to be well accepted overall, the willingness to use this type of contraception varies widely between differing population groups. The specific characteristics and profile of any MFC product will have to be carefully evaluated to accurately assess its acceptance, both by men and their female partners. 相似文献
10.
The effects of co-culture with human fibroblasts on human embryo development in vitro and implantation 总被引:5,自引:0,他引:5
Wetzels AM; Bastiaans BA; Hendriks JC; Goverde HJ; Punt-van der Zalm AP; Verbeet JG; Braat DD 《Human reproduction (Oxford, England)》1998,13(5):1325-1330
In a human in-vitro fertilization (IVF) programme, the effect of co-
culture of embryos with human fibroblasts was evaluated with respect to
pregnancy rate and embryo development. Patients were included in the study
after giving informed written consent. The IVF treatments were randomly
assigned by stratification of both age (<36 versus > or =36 years)
and previous IVF attempts (yes versus no). After fertilization was
established, the zygotes were transferred to a 4-well dish with or without
fibroblasts and cultured for 2 days. On the third day after ovum pick-up
(OPU), cell number and quality [5 (good) to 1 (poor)] of the embryos were
scored and a maximum of three embryos was transferred. Supernumerary
embryos of good quality were cryopreserved. The design of this study was a
group sequential trial with the objective of detecting differences between
pregnancy rates following IVF with conventional incubation or incubation in
co-culture with fibroblasts. This design included one evaluation at
half-way data collection. In the study, 148 patients had an OPU, of whom 77
were allocated to the co-culture group. There was no statistically
significant difference in pregnancy rate, cell number and embryo quality
between the two groups. The ongoing pregnancy rate per embryo transfer was
27% in co-culture and 30% in the conventional culture group. The
implantation rates per transferred embryo were 17 and 18% respectively.
Using a multivariate logistic regression model for the probability of
ongoing pregnancies, the odds ratio of co-culture, adjusted for age and
previous IVF attempts, was not statistically significant. In conclusion,
co-culture with human fibroblasts does not contribute to an improvement of
embryo quality nor to a higher pregnancy rate after IVF in an unselected
group of patients.
相似文献