全文获取类型
收费全文 | 16406篇 |
免费 | 1207篇 |
国内免费 | 66篇 |
专业分类
耳鼻咽喉 | 127篇 |
儿科学 | 500篇 |
妇产科学 | 446篇 |
基础医学 | 2702篇 |
口腔科学 | 391篇 |
临床医学 | 1523篇 |
内科学 | 3608篇 |
皮肤病学 | 249篇 |
神经病学 | 1360篇 |
特种医学 | 304篇 |
外科学 | 1936篇 |
综合类 | 108篇 |
一般理论 | 10篇 |
预防医学 | 1562篇 |
眼科学 | 323篇 |
药学 | 1463篇 |
中国医学 | 47篇 |
肿瘤学 | 1020篇 |
出版年
2023年 | 92篇 |
2022年 | 227篇 |
2021年 | 425篇 |
2020年 | 275篇 |
2019年 | 369篇 |
2018年 | 410篇 |
2017年 | 340篇 |
2016年 | 330篇 |
2015年 | 435篇 |
2014年 | 558篇 |
2013年 | 745篇 |
2012年 | 1111篇 |
2011年 | 1181篇 |
2010年 | 659篇 |
2009年 | 576篇 |
2008年 | 989篇 |
2007年 | 998篇 |
2006年 | 939篇 |
2005年 | 846篇 |
2004年 | 726篇 |
2003年 | 693篇 |
2002年 | 686篇 |
2001年 | 294篇 |
2000年 | 323篇 |
1999年 | 293篇 |
1998年 | 147篇 |
1997年 | 126篇 |
1996年 | 90篇 |
1995年 | 118篇 |
1994年 | 93篇 |
1993年 | 91篇 |
1992年 | 232篇 |
1991年 | 219篇 |
1990年 | 218篇 |
1989年 | 197篇 |
1988年 | 154篇 |
1987年 | 185篇 |
1986年 | 150篇 |
1985年 | 123篇 |
1984年 | 121篇 |
1983年 | 107篇 |
1982年 | 75篇 |
1981年 | 67篇 |
1980年 | 50篇 |
1979年 | 90篇 |
1978年 | 83篇 |
1977年 | 60篇 |
1974年 | 53篇 |
1973年 | 45篇 |
1972年 | 44篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
B Sandstr?m A Cederblad B Stenquist H Andersson 《European journal of clinical nutrition》1990,44(10):705-708
Colonic retention of zinc and calcium was studied after installation during colonoscopy in 11 patients of a solution of 30 mumol zinc, 6.4 mmol calcium and 500 mumol inositol hexaphosphate (phytic acid) labelled with 65Zn and 47Ca. Whole-body retention of the radionuclide at day 13 was 1.0 +/- 1.0 per cent (mean +/- s.d.) for zinc and 4.0 +/- 2.9 per cent for calcium. The retention of zinc but not of calcium was lower than observed earlier under similar conditions from a solution not containing phytic acid and indicates formation of an indigestible complex between phytic acid and zinc. Addition of amino acids to the solution in 3 subjects did not seem to affect the retention of zinc and calcium. 相似文献
32.
M J Buxton S D Sullivan L F Andersson C J Lamm B Liljas W W Busse S Pedersen K B Weiss 《The European respiratory journal》2004,24(4):568-574
Early intervention with budesonide is an effective strategy for mild persistent asthma, which has been shown to provide additional clinical benefits at a low incremental cost using USA cost data. The present authors analysed whether this strategy would be cost-effective using cost data for other countries. Based on the 3-yr prospective, randomised, double-blind inhaled Steroid Treatment As Regular Therapy (START) in early asthma study (comparing budesonide and placebo combined with usual asthma therapy), the cost-effectiveness was estimated separately for eight different countries, from both healthcare payer and societal perspectives, of adding budesonide to usual asthma therapy. Local unit costs were applied to data for the total trial population. Incremental cost-effectiveness ratios (ICER) were estimated as cost per symptom-free day (SFD) gained. Budesonide increased SFDs by an average of 14.1 days annually. From a healthcare payer perspective, budesonide would reduce the total cost of asthma care in Australia. In Sweden, Canada, France, Spain, UK, China and the USA, the ICER ranged from US$2.4-11.3 per SFD. From a societal perspective, budesonide would be cost-saving in Australia, Canada and Sweden. In conclusion, for countries where costs with budesonide are higher, the policy implication has to be determined by that health system's willingness to pay for an additional symptom-free day. However, where budesonide therapy increases symptom-free days and reduces total costs, the policy conclusion clearly favours early intervention. 相似文献
33.
This study aimed to evaluate stallion sperm survival after 24 h of cooled storage in the presence of seminal plasma (SP) derived from the sperm‐rich fractions (SRF) or sperm‐poor fractions(SPF) of the ejaculate, without SP, or in the presence of SP from other stallions. Ejaculates were collected from four stallions using an automated phantom, which separated the semen into five cups. Centrifuged and washed spermatozoa from cup 2 (SRF) were mixed with skim milk extender to a concentration of 100 × 106 sperm/ml and then 1:1 (v/v) with SP from the stallion's own or another stallions’ second (SP‐SRF) or last cup (SP‐SPF). Skim milk extender (K) and skim milk extender supplemented with modified Tyrode's medium (KMT) were used as control treatments. After a 24‐h storage period in a transport container, spermatozoa were evaluated for motion characteristics and plasma membrane integrity by calcein acetoxymethyl (AM)/propidium iodide staining. The percentage of spermatozoa with intact plasma membranes after storage was lower in SP‐SRF than in SP‐SPF, and the highest in K (P < 0.05). Progressive motility (PMOT) was lower for sperm stored in SP‐SRF than for sperm stored in SP‐SPF (P < 0.05), but there was no significant difference in total motility (TMOT). Sperm stored in KMT (P < 0.05) registered the highest TMOT and PMOT percentages. Osmolarity was significantly higher and pH lower in K than in KMT or SP. Treatment with SP‐SPF from three stallions benefited the PMOT of sperm from one stallion. These preliminary findings suggest that SP from SRFs may be more harmful during storage than SP from SPFs. Removal of SP improves sperm survival in KMT extender, and exchanging SP between stallions seems to influence sperm survival. 相似文献
34.
Massimo Bolognesi M.D. Claudio R. Nigg Ph.D. Massimo Massarini M.D. Sonia Lippke Ph.D. 《Annals of behavioral medicine》2006,31(2):179-185
Background: There is an alarming prevalence of obesity and sedentariness in Western countries. An ideal context for health promotion
and preventive medicine seems to be the setting of primary care provided by the general practitioner (GP).Purpose: Therefore, this study evaluated the impact of GPs’brief physical activity counseling for overweight and obese patients.Methods: Individuals recruited during routine physician visits were randomly split into an experimental (n = 48) group that received
the Patient-centered Assessment and Counseling for Exercise (PACE) protocol, and a usual-care control (n = 48) group. Body
mass index (BMI) and abdominal girth were assessed as objective biometrical parameters. Patients in the experimental group
self-reported their readiness for physical activity and self-efficacy.Results: The experimental group had significantly better BMI and abdominal girth compared with the control group after a 5- to 6-month
follow-up. Furthermore, the experimental group progressed in their stage of physical activity readiness and increased their
self-efficacy.Conclusions: The GPs’counseling for physical activity using the PACE protocol influenced mediators and biometrical outcomes in an Italian
primary care context.
An earlier version of this article was presented for the degree thesis in Community Psychology at the Bologna University.
The advisor was Professor Bruna Zani.
We thank the general practitioners who contributed to this project: Marcatelli M., Forgiarini A., Fabbri M., De Astis R.,
Aguzzoni F., Barbarossa L., Montalti M. (Azienda USL-Distretto di Cesena Italy), and we thank Silvano Zanuso (Technogym Research
Center-Gambettola Italy) for his helpful comments. 相似文献
35.
36.
D Lundgren H Rylander M Andersson C Johansson T Albrektsson 《Clinical oral implants research》1992,3(3):136-143
The aim of these animal experiments was to characterize and evaluate the healing-in of root analogue titanium implants fitting with high precision to the alveolar wall. Four beagle dogs were used in the study. The roots of the 3rd and 4th mandibular premolars in both quadrants of 3 dogs and in 1 quadrant of 1 dog (dog 4) were extracted after hemisection. Each root was machine-copied to 1 titanium analogue. In dog 4, however, 2 titanium analogues were fabricated from each of the 4 extracted roots. This enabled insertion of analogues also into the contralateral sockets obtained by extraction of the corresponding roots immediately before implant installation, which was undertaken 2 weeks after the first extractions. Thus, in all, 32 analogues were implanted in their respective (or contralateral) sockets following ridge incision and elevation of mucoperiosteal flaps. The analogues were carefully covered by the repositioned flaps. In dog 4, 2 analogues from the immediate sockets and 2 from the 2-week sockets were surgically exposed and supplied with titanium crowns after a healing period of 2 months. The healing after implantation was evaluated by clinical, radiographic and histological measures after 2, 12 or 36 months. Two analogues (6%) were lost due to early (during the 1st week) exposure to the oral cavity. Another 2 analogues (6%) were, although not exposed, encapsulated by soft tissue and were easily removed with a surgical forceps. Twenty-eight analogues (88%) were healed-in by contact between bone and implant (osseointegration).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
37.
38.
Two topical corticosteroids, budesonide (BUD) and beclomethasone dipropionate (BDP), both administered as suspensions in water, were investigated in healthy volunteers regarding influence on cortisol in plasma and urine (U-cortisol) after nasal application. In the first study, single doses of 200, 400, and 800 μg of BDP and BUD were given at 10:00 pm. In the second study, 100, 200, and 400 μg were given mornings and evenings for 4 days. In the single-dose study, none of the drugs or doses showed any significant influence on cortisol in plasma. However, U-cortisol decreased significantly after BUD 400 and 800 μg. In the multidose study, U-cortisol values were significantly reduced after all doses of BUD and the highest dose of BDP. The compounds tested showed different ability to cause measurable systemic effects after nasal application. The clinical implication is that the prescriber, when choosing a compound, should take the application site into consideration and should also be encouraged to find the lowest effective dose. 相似文献
39.
Y. Tani T. Ishihara T. Kanai T. Ohno J. Andersson A. Lilja G. Antoni K. -J. Fasth P. Bjurling G. Westerberg P. Hartvig H. Onoe Y. Watanabe B. Langström 《Journal of neural transmission (Vienna, Austria : 1996)》1995,102(3):189-208
Summary The effects of 6R-L-erythro-5,6,7,8-tetrahydrobiopterin (R-THBP) on the central cholinergic and dopaminergic systems in the Rhesus monkey brain were investigated by positron emission tomography (PET) with the muscarinic cholinergic receptor ligands (N-[11C]methyl-benztropine) and dopaminergic receptor ligands selective for D1 D2, and D3 subtypes ([11C]SCH23390, N-[11C]methyl-spiperone, and (+)[11C]UH232, respectively). None of the doses (3, 10, and 30 mg/kg i.v.) of R-THBP used significantly affected the regional cerebral blood flow (rCBF as determined by Raichle's H2
15O method), and 10 mg/kg of R-THBP had little effect on the regional cerebral metabolic rate of glucose (rCMRglc) in the Rhesus monkey brain, as assessed by the graphical [18F]fluoro-deoxyglucose method. The effect of R-THBP on the muscarinic cholinergic system was dose dependent; while 3 mg/kg of R-THBP did not significantly alter the uptake ratio of N-[11C]methyl-benztropine in several brain regions to that in the cerebellum, 10 and 30 mg/kg of R-THBP significantly reduced the uptake ratio in the thalamus, as well as in the frontal and temporal cortices. None of the doses (3, 10, and 30 mg/kg i.v.) of R-THBP tested affected [11C]SCH23390 (dopamine D1 receptor) binding. However, the k3 value for N-[11C]methyl-spiperone (dopamine D2 receptor) binding, which represents the association rate × Bmax value, was significantly decreased in the striatum. The uptake ratio of (+)[11C]UH232 (dopamine D3 receptor) in the striatum to that in the cerebellum was also decreased by administration of R-THBP (3 and 30 mg/kg i.v.). These findings suggest that R-THBP acts on dopamine D2 and D3 receptors selectively without markedly affecting dopamine D1 receptor binding. Furthermore, the changes in cholinergic and dopamine D2 and D3 receptors in vivo can not be attributed to a change in rCBF but may depend on the action of R-THBP.Abbreviations
R-THBP
6R-L-erythro-5,6,7,8-tetrahydrobiopterin
-
PET
positron emission tomography
-
rCBF
regional cerebral blood flow
-
rCMRglc
regional cerebral metabolic rate of glucose 相似文献
40.
M. Andersson L. Greiff C. Svensson C. Persson 《European archives of oto-rhino-laryngology》1995,252(1):S22-S26
Hyper-reactivity to non-specific challenges has been considered a hallmark of asthma and is defined as an abnormal responsiveness of the bronchial airways to a variety of provocative agents. The mechanisms underlying hyper-reactivity in the upper and lower airways are not known. By using the nose to study the inflammatory response possible abnormalities can be investigated carefully and pathophysiology of specific airway hyper-reactivities can be better understood. Other factors than merely constriction of the bronchial smooth muscles can cause narrowing of the free lumen to airflow. Functionally different and very distinct mucosal end-organ reactivities may also be increased. If these reactivities can be well assessed, specific airway hyper-reactivity can be defined. In the present report, specific mucosal end-organ hyper-reactivites in the allergic nasal mucosa are presented. Certain widespread hypotheses, such as the role of the eosinophil and the “increased absorption permeability theory”, are disputed. 相似文献