全文获取类型
收费全文 | 26342篇 |
免费 | 2551篇 |
国内免费 | 787篇 |
专业分类
耳鼻咽喉 | 183篇 |
儿科学 | 269篇 |
妇产科学 | 240篇 |
基础医学 | 1028篇 |
口腔科学 | 571篇 |
临床医学 | 4236篇 |
内科学 | 1963篇 |
皮肤病学 | 211篇 |
神经病学 | 878篇 |
特种医学 | 620篇 |
外国民族医学 | 7篇 |
外科学 | 1608篇 |
综合类 | 4386篇 |
现状与发展 | 1篇 |
一般理论 | 1篇 |
预防医学 | 6321篇 |
眼科学 | 118篇 |
药学 | 3798篇 |
92篇 | |
中国医学 | 2353篇 |
肿瘤学 | 796篇 |
出版年
2024年 | 201篇 |
2023年 | 690篇 |
2022年 | 1107篇 |
2021年 | 1292篇 |
2020年 | 1407篇 |
2019年 | 1118篇 |
2018年 | 1059篇 |
2017年 | 1077篇 |
2016年 | 1138篇 |
2015年 | 1097篇 |
2014年 | 2220篇 |
2013年 | 2244篇 |
2012年 | 1944篇 |
2011年 | 1898篇 |
2010年 | 1439篇 |
2009年 | 1288篇 |
2008年 | 1177篇 |
2007年 | 1133篇 |
2006年 | 982篇 |
2005年 | 785篇 |
2004年 | 655篇 |
2003年 | 559篇 |
2002年 | 440篇 |
2001年 | 400篇 |
2000年 | 317篇 |
1999年 | 314篇 |
1998年 | 251篇 |
1997年 | 186篇 |
1996年 | 170篇 |
1995年 | 143篇 |
1994年 | 140篇 |
1993年 | 104篇 |
1992年 | 107篇 |
1991年 | 85篇 |
1990年 | 70篇 |
1989年 | 59篇 |
1988年 | 54篇 |
1987年 | 38篇 |
1986年 | 45篇 |
1985年 | 53篇 |
1984年 | 46篇 |
1983年 | 20篇 |
1982年 | 22篇 |
1981年 | 22篇 |
1980年 | 27篇 |
1979年 | 10篇 |
1978年 | 16篇 |
1977年 | 13篇 |
1975年 | 8篇 |
1974年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
The Student Training, Education and Practice for Dietetics (STEP‐DIET) CD‐ROM was developed at the University of Surrey to prepare dietetic students for the practical dietetic training component of their Nutrition/Dietetics degree. This study aimed to evaluate student response to the programme and its effectiveness as a teaching tool, based on the evaluation framework of D.L. Kirkpatrick (Evaluating a Course, 2nd edn. London, Kogan Page). Quantitative and qualitative methodologies were employed, with 41 dietetic students, separated by year group, completing questionnaires and taking part in six focus groups, at the University of Surrey. Student attitudes towards the instruction method and the STEP‐DIET programme itself were investigated, in conjunction with their perceived learning achievements. Students rated the programme highly in terms of design and content, however, there was a reluctance to accept computer‐assisted instruction (CAI) as a sole teaching method. A number of learning achievements relevant to dietetic practice were reported including a perceived increase in ability to conduct a dietetic interview and an increased understanding of the management of Type 2 diabetes. In general students reacted positively to the STEP‐DIET programme and it was perceived by students to be effective in preparing them for the practical component of their dietetic training. 相似文献
12.
Michael C. Kontos Kristin L. Schmidt Michael McCue Louis F. Rossiter Michael Jurgensen Christopher S. Nicholson Robert L. Jesse Joseph P. Ornato James L. Tatum 《Journal of nuclear cardiology》2003,10(3):284-290
BACKGROUND: Our objective was to determine the cost-effectiveness of a comprehensive, risk-based triage system, composed of multiple critical pathways, with the use of early myocardial perfusion imaging (MPI) in low-risk patients. We found previously that a chest pain evaluation system that uses MPI in low-risk patients was safe and effective, but the cost-effectiveness of this approach was not studied. METHODS AND RESULTS: We compared two groups. The Acute Cardiac Team (ACT) group (n = 874) was assigned prospectively to 1 of 4 risk levels by emergency department (ED) physicians. Level 1, 2, and 3 patients were admitted; level 4 patients were evaluated in the ED. Level 3 and 4 patients underwent ED MPI. The control group (n = 713) represented consecutive patients evaluated in the prior year according to standard care and assigned retrospectively to an ACT level based on the presenting electrocardiographic and clinical data. Record and hospital administrative data were assessed for clinical variables, outcomes, lengths of stay, and all expenses incurred within 30 days of the index visit. The baseline characteristics of the two groups were similar, including age, sex, myocardial infarction prevalence, and 30-day revascularization rates within each level or between the two groups. Mean costs per encounter were reduced for the ACT patients for each level, which was significant when all patients were compared ($5,030 +/- $7,081 vs $6,044 +/- $10,432, P =.02). Use of MPI in the low-risk patients was associated with reduced costs (level 3, $4,958 +/- $4,948 vs $5,051 +/- $7,036; level 4, $1,529 +/- $2,664 vs $1,794 +/- $6,854) and was associated with a significantly lower angiography rate and shorter length of stay. CONCLUSIONS: Implementation of a comprehensive strategy for chest pain evaluation and triage reduced overall costs for patients with chest pain on presentation. Acute MPI in the ED setting did not increase net cost. 相似文献
13.
Clinical evaluation of a potassium nitrate dentifrice for the treatment of dentinal hypersensitivity
Toshihiko Nagata Hiroshi Ishida Hiroyuki Shinohara Seiji Nishikawa Shinji Kasahara Yoichi Wakano Shusaku Daigen Emanuel S. Troullos 《Journal of clinical periodontology》1994,21(3):217-221
Abstract The effectiveness of a 5% potassium nitrate dentifrice as a daily home treatment for dentinal hypersensitivity was evaluated in a double-blind study in 36 Japanese subjects who complained of cold and/or tactile hypersensitivity. The subjects were divided into 2 groups, with 18 being given a 5% potassium nitrate dentifrice (treated group) and the other 18 a vehicle paste (control group). Both groups were instructed to brush their teeth 2 × a day. The hypersensitivity levels of the affected teeth were assessed by 2 stimuli, one tactile and the other cold air, and by the perception of pain. The results of all 3 assessment methods indicated that the potassium nitrate dentifrice significantly decreased the level of hypersensitivity at weeks 4, 8, and 12. In the treated group, a rapid decrease of positive scores for both the cold air stimulus and the subjective symptoms appeared from week 2. Although a significant decrease of the assessment score was also observed in the control group, the reduction rate of the score was much greater in the treated group by ail 3 assessment methods at weeks 4, 8, and 12. Complete relief of subjective symptoms throughout the 12 weeks’examination was noted in 67% of the subjects in the treated group, but in only 6% in the control group. These results suggest the usefulness of a 5% potassium nitrate dentifrice in Japanese patients with dentinal hypersensitivity. 相似文献
14.
城市公共厕所发展趋势的探讨 总被引:1,自引:1,他引:0
介绍了改革开放以来各地出现的一些新型公厕,认为前店后厕、附属式公厕、生态公厕是发展趋势,而豪华型公厕的推广目前尚不具备条件. 相似文献
15.
16.
A postal survey of 100 hospitals throughout the United Kingdom and Ireland was conducted to assess current practice in the pre-operative assessment and use of pulmonary artery catheters in patients undergoing elective abdominal aortic aneurysm repair. Seventy-four completed questionnaires were received. The survey revealed that 53% of respondents hold designated pre-operative assessment clinics, attended by anaesthetists in 54% and cardiologists in 26%. However, only 4% of respondents have a written protocol for stratifying patients and assessing peri-operative risk. By far the commonest investigation of choice for further cardiological assessment is transthoracic echocardiography (67%). Other investigations of choice are multiple update gated acquisition (MUGA) scan (13%), dipyridamole thallium imaging (9%), exercise ECG (6%), stress echocardiography (1%) and stress MUGA (1%). Two units (3%) never undertook further investigation. Pulmonary artery flotation catheters are used as a routine by 9% of respondents, dependent upon left ventricular ejection fraction by 65%, dependent on other factors by 7% and not used at all by 19%. The survey reveals widespread variation in pre-operative assessment of patients undergoing elective repair of abdominal aortic aneurysm. 相似文献
17.
We assessed the feasibility and psychometric properties of two commonly used health status questionnaires in Parkinson's disease (PD): the generic Nottingham Health Profile (NHP) and the disease-specific 39-item Parkinson's disease Questionnaire (PDQ-39), from a cross-sectional postal survey of PD patients (N = 81), using traditional and Rasch measurement methodologies. Overall response rate was 88%. Both questionnaires were found feasible, although the NHP performed less well. The PDQ-39 had fewer floor effects and was better able to separate respondents into distinct groups than the NHP, whereas the latter exhibited less ambiguous dimensionality and better targeting of respondents with non-extreme scores. Reliability and validity indices were similar, and potential differential item functioning by age and gender groups was found for both questionnaires. PDQ-39 response alternatives indicated ambiguity. With few exceptions, questionnaire scales were unable to meet recommended standards fully. While preliminary, this study illustrates the need for thorough evaluation of outcome measures and has implications beyond the questionnaires used here. Although promising, both questionnaires warrant further developmental work and stronger support of measurement validity before they could be considered fully suitable for valid use in PD, in particular in earlier stages of the disease. 相似文献
18.
19.
Summary: Some of the properties of 4–bromobenzalde-hyde semicarbazone (compound IV), a prototype molecule of a new class of anticonvulsants, aryl semicarbazones, are described. Compound IV demonstrated activity in the maximal electroshock (MES) and subcutaneous pentylenetetrazol (scPTZ) tests in mice, with low neurotoxicity. When given orally to rats, it displayed high potency in the MES test and very low neurotoxicity, resulting in a high protective index (PI). Compound IV displayed no proconvulsant properties, and development of rapid tolerance was not noted. When administered intraperitoneally (i.p.) at doses of 100, 300, or 600 mg/kg to rats, compound IV had no effect on levels of γ-aminobu-tyric acid (GABA) or on GABA-T activity in whole brain. When tested in vitro, compound IV had no effect on rat brain GABA-T at a drug concentration of 100 μM. Although the activities of certain drug-metabolizing enzymes were increased after oral administration of compound IV to rats, these effects were less prominent than those of phenytoin (PHT) and carbamazepine (CBZ). The principal mode of action of compound IV does not appear to be an interaction with the GABAA receptor complex, and other mechanisms, involving excitatory amino acid neurotransmission, will have to be considered in future investigations of the anticonvulsant activity of this compound. 相似文献
20.
Monitoring of skin response to sodium lauryl sulphate: clinical scores versus bioengineering methods
The present trial was designed to evaluate clinical scores (single observer) of sodium lauryl sulphate (SLS)-induced skin irritation in a group of subjects (n = 10) over a 10-day period along with various skin function parameters. In order to avoid significant variations due to secondary phenomena, the following parameters were recorded with non-invasive instruments in this order: skin capacitance (C1; arbitrary units; CM420 Corneometer), transepidermal water loss (TEWL; g/m2.h; Evaporimeter) and laser Doppler flowmetry (CBFV: cutaneous blood flow values; Periflux). All examinations were performed during winter on reclined relaxed subjects present for at least 10 min in a test room with controlled temperature and relative humidity (t degrees: 19.5-20.7 degrees C and RH: 47.3-60.3%). The analysis of differential data (delta = value at tx-value before test; 2-way ANOVA) was made on single parameters as a function of site (volar forearm versus neck) and time (from 24 h after 48-h occlusion with 5% SLS up to 10 days later). The profile of erythema scores over time differed between neck and forearm, but the delta CBFV readings with the laser Doppler instrument did not detect significant site-time interactions. Roughness (blind evaluation with palpating finger) and capacitance readings (delta C1) showed significant differences between sites, but the profile over time was similar in both locations. delta TEWL did not differ according to anatomical location. The reason for different erythema scores on neck and forearm might be related to inherent regional variation of optical properties of the skin or to a substantial contribution of SLS-induced roughness to the readings of erythema.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献