全文获取类型
收费全文 | 164365篇 |
免费 | 43121篇 |
国内免费 | 1585篇 |
专业分类
耳鼻咽喉 | 2062篇 |
儿科学 | 6169篇 |
妇产科学 | 1058篇 |
基础医学 | 31690篇 |
口腔科学 | 7220篇 |
临床医学 | 16536篇 |
内科学 | 33071篇 |
皮肤病学 | 5176篇 |
神经病学 | 23359篇 |
特种医学 | 6754篇 |
外国民族医学 | 4篇 |
外科学 | 19274篇 |
综合类 | 5057篇 |
现状与发展 | 2篇 |
一般理论 | 8篇 |
预防医学 | 10261篇 |
眼科学 | 1931篇 |
药学 | 19392篇 |
7篇 | |
中国医学 | 3568篇 |
肿瘤学 | 16472篇 |
出版年
2023年 | 1039篇 |
2022年 | 2145篇 |
2021年 | 3574篇 |
2020年 | 7418篇 |
2019年 | 13176篇 |
2018年 | 12580篇 |
2017年 | 13532篇 |
2016年 | 12345篇 |
2015年 | 12500篇 |
2014年 | 13034篇 |
2013年 | 13830篇 |
2012年 | 12389篇 |
2011年 | 12813篇 |
2010年 | 11115篇 |
2009年 | 7571篇 |
2008年 | 8258篇 |
2007年 | 6491篇 |
2006年 | 6146篇 |
2005年 | 5640篇 |
2004年 | 5436篇 |
2003年 | 4917篇 |
2002年 | 4374篇 |
2001年 | 3372篇 |
2000年 | 2279篇 |
1999年 | 1017篇 |
1998年 | 829篇 |
1997年 | 773篇 |
1996年 | 659篇 |
1995年 | 613篇 |
1994年 | 539篇 |
1993年 | 506篇 |
1992年 | 472篇 |
1991年 | 438篇 |
1990年 | 383篇 |
1989年 | 342篇 |
1988年 | 283篇 |
1987年 | 272篇 |
1986年 | 263篇 |
1985年 | 575篇 |
1984年 | 667篇 |
1983年 | 446篇 |
1982年 | 541篇 |
1981年 | 508篇 |
1980年 | 472篇 |
1979年 | 433篇 |
1978年 | 393篇 |
1977年 | 284篇 |
1976年 | 334篇 |
1975年 | 300篇 |
1974年 | 273篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Stanislas Grassin‐Delyle Michaela Semeraro Frantz Foissac Naim Bouazza Haleema Shakur‐Still Ian Roberts Jean‐Marc Treluyer Saïk Urien 《Fundamental & clinical pharmacology》2019,33(6):670-678
Tranexamic acid (TXA) is an antifibrinolytic drug that reduces surgical blood loss and death due to bleeding after trauma and post‐partum haemorrhage. One key issue for treatment success is early administration. While usually given intravenously, oral and intramuscular use would be useful in specific circumstances. Therefore, an understanding of TXA pharmacokinetics when given via different routes is valuable. The aim of this study was to perform an individual participant data meta‐analysis of pharmacokinetic studies with TXA given to healthy volunteers via different routes. We searched the following databases: PubMed, Web of Science, Wiley Online Library, Elsevier Science Direct and J‐STAGE. Individual subject data were extracted when available, otherwise arithmetic means were used. A population pharmacokinetic model was developed using nonlinear mixed effect modelling. Seven studies were included in the analysis with data from 10 patients for the IV route, six patients for the IM route and 114 patients for the oral route. The pharmacokinetics was ascribed to a two‐compartment model, and the main covariate was allometrically scaled bodyweight. Oral and IM bioavailabilities were 46 and 105%, respectively. For a 70 kg bodyweight, the population estimates were 7.6 L/h for clearance, 17.9 L for the volume of the central compartment, 2.5 L/h for the diffusional clearance and 16.6 L for the peripheral volume of distribution. Larger well‐designed studies are needed to describe the pharmacokinetics of TXA when given IM or as an oral solution before these can be recommended as alternatives to IV. 相似文献
92.
93.
OBJECTIVES: To assess the effectiveness and safety of additional bedtime H2‐receptor antagonists (H2RAs) in suppressing nocturnal gastric acid breakthrough (NAB) via a systematic review. METHODS: Eligible trials were identified by searching the Cochrane Central Register of Controlled Trials (CENTRAL) (Cochrane Library Issue 2, 2004), MEDLINE (January 1966–June 2004), EMBASE (January 1980–June 2004) and CINAHL (January 1982–June 2004). Additional hand‐searching was conducted on the proceedings of correlated conferences, eight important Chinese journals and references of all included trials. All randomized controlled trials evaluating H2RAs for the control of NAB were eligible for inclusion. The systematic review was conducted using methods recommended by The Cochrane Collaboration. RESULTS: Only two randomized crossover studies, comprising 32 participants, met the inclusion criteria. Because the design, dosage and duration of the treatments were different between the studies, it was not possible to conduct meta‐analysis. There were no consistent conclusions found between the two included studies in evaluating H2RAs for the control of NAB. CONCLUSIONS: No implications for practice at this stage can be concluded. Appropriately designed large‐scale randomized controlled trials with long‐term follow up are needed to determine the effects of additional bedtime H2RAs in suppressing NAB. 相似文献
94.
Consensus on the use and monitoring of anti‐TNF‐α therapies for rheumatic diseases in Hong Kong 2005
《International journal of rheumatic diseases》2006,9(2):175-180
The development and use of the tumour necrosis factor (TNF) antagonists is a major breakthrough in the treatment of many rheumatic diseases. Although these novel agents are undoubtedly superior to conventional therapeutic modalities, their costs and potential adverse effects are of concern. The current consensus statements were developed in early 2005 to help practicing rheumatologists identify which adult patients may benefit from anti‐TNF therapies and highlight their potential toxicities. The Hong Kong Society of Rheumatology has developed a registry on the use of the biologics in our local patients with chronic rheumatic disorders. Because the indications and novel data regarding the TNF inhibitors are ever changing, this consensus will be updated regularly. 相似文献
95.
N. SUVAJD
I V. EMERIKI‐MARTINOVI . ARANOVI M. PETROVI M. POPOVI V. ARTIKO M. UPI I. ELEZOVI 《International journal of laboratory hematology》2006,28(5):317-320
We report the case of a littoral‐cell angioma of the spleen, a recently described benign vascular tumour, whose imaging and pathological characteristics have been discussed only by a few authors. The diagnosis was made after elective splenectomy. The CT images, scintigraphy and histological specimens are presented, and differential diagnoses discussed. 相似文献
96.
《Journal of labelled compounds & radiopharmaceuticals》2006,49(4):339-343
Condensation of thiourea 1 with diethyl malonate 2 in the presence of sodium methoxide furnished 4,6‐dihydroxy‐2‐mercaptopyrimidine 3 . Compound 3 on methylation with diazomethane followed by oxidation with H5IO6/CrO3 in ethyl acetate gave 4,6‐dimethoxy‐2‐methylsulphonylpyrimidine 5 . Compound 5 on condensation with 2‐mercapto‐6‐chlorobenzoic acid in the presence of a phase transfer catalyst, tetrabutylammonium bromide and sodium carbonate gave the title compound – pyrithiobac‐sodium 6 with an overall yield of > 35% starting from thiourea. Following the above standardized procedure, using [14C]‐thiourea in lieu of thiourea, 14C labelled product 6 , was synthesized with an overall radiochemical yield > 30% (with respect to [14C]‐thiourea) for further evaluations of environmental fate of 6 , in soils and plants. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
97.
The use of endogenous Protoporphyrin IX generated through the heme biosynthetic pathway after administration of 5-aminolevulinic acid (ALA) has led to many applications in photodynamic therapy (PDT). In Buenos Aires, Argentina, the Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP), reported for the first time, in 1975, porphyrin synthesis from ALA in highly dividing plant tissues. Increased porphyrin synthesis in tumours as well as cell photosensitisation was reported soon after. Our group is also interested in studying the use of new synthetic lipophilic derivatives of ALA as well as ALA delivery in liposomes. We have elucidated the mechanism of ALA transport in mammalian and yeast cells. The interactions between ALA-PDT and nitric oxide were investigated in three murine adenocarcinoma cell lines. In the National University of Río Cuarto, Córdoba, a group is devoted to the synthesis of new porphyrin-derived photosensitisers to study their effects on photoinactivation of bacterial and mammalian cells death by PDT. At the Centre of Electron Microscopy of the Cordoba National University, a prototype of a 630 nm noncoherent light source was designed and constructed. Cost of the light source and scarce knowledge of the benefits of PDT by physicians limit the spread of the treatment throughout the country. 相似文献
98.
A method is presented for 3D MRI in an extended field of view (FOV) based on continuous motion of the patient table and an efficient acquisition scheme. A gradient-echo MR pulse sequence is applied with lateral (left-right (L/R)) frequency-encoding direction and slab selection along the direction of motion. Compensation for the table motion is achieved by a combination of slab tracking and data alignment in hybrid space. The method allows fast k-space coverage to be achieved, especially when a short sampling FOV is chosen along the direction of table motion, as is desirable for good image quality. The method can be incorporated into different acquisitions schemes, including segmented k-space scanning, which allows for contrast variation with the use of magnetization preparation. Head-to-toe images of volunteers were obtained with good quality using 3D spoiled gradient-echo sequences. As an example of magnetization-prepared imaging, fat/water separated images were acquired using chemical shift selective (CHESS) presaturation pulses. 相似文献
99.
Fast CT-PRESS-based spiral chemical shift imaging at 3 Tesla. 总被引:2,自引:0,他引:2
Dirk Mayer Dong-Hyun Kim Elfar Adalsteinsson Daniel M Spielman 《Magnetic resonance in medicine》2006,55(5):974-978
A new sequence is presented that combines constant-time point-resolved spectroscopy (CT-PRESS) with fast spiral chemical shift imaging. It allows the acquisition of multivoxel spectra without line splitting with a minimum total measurement time of less than 5 min for a field of view of 24 cm and a nominal 1.5x1.5-cm2 in-plane resolution. Measurements were performed with 17 CS encoding steps in t1 (Deltat1=12.8 ms) and an average echo time of 151 ms, which was determined by simulating the CT-PRESS experiment for the spin systems of glutamate (Glu) and myo-inositol (mI). Signals from N-acetyl-aspartate, total creatine, choline-containing compounds (Cho), Glu, and mI were detected in a healthy volunteer with no or only minor baseline distortions within 14 min on a 3 T MR scanner. 相似文献
100.
Eijiro Morita Torao Tanaka Tetsuya Nakamura Fumitaka Terabe Ichiro Hirata Kenichi Katsu Masakazu Takazoe Akira Terano 《Digestive endoscopy》2006,18(4):263-268
Background and Aims: Video capsule endoscopy (VCE) has become increasingly important as a simple method for observing the entire small intestine. The indications for VCE are obscure gastrointestinal bleeding and investigation of Crohn’s disease (CD). However, the correlation between endoscopic findings obtained by VCE and clinical findings in known cases of CD is not clear, and we therefore investigated this in the present study. Patients and methods: In 30 patients with known CD (Crohn’s disease activity index [CDAI] 0–420; median = 158.3), double contrast enteroclysis (ENT) was performed 1–3 weeks prior to VCE. The relationship between the VCE findings and hematological analysis/CDAI was examined. Results: In 17 of 30 patients, the entire small intestine could be investigated by VCE, whereas in the remaining 13 patients the terminal ileum could not be investigated. The following exhibited positive correlations: total lesions and CDAI (correlation coefficient values: rs = 0.661, adjusted P < 0.0061), ulcers and C‐reactive protein (CRP) (rs = 0.607, adjusted P < 0.0061), total lesions and CRP (rs = 0.604, adjusted P < 0.0061). Conclusions: Analysis with VCE suggests that CDAI and CRP indicate the activity of intestinal lesions in patients with known CD, and that CRP, in particular, is associated with the activity of ulcerative lesions of the intestine. This may contribute to revised guidelines for VCE in the future. 相似文献