全文获取类型
收费全文 | 17703篇 |
免费 | 1090篇 |
国内免费 | 48篇 |
专业分类
耳鼻咽喉 | 209篇 |
儿科学 | 359篇 |
妇产科学 | 459篇 |
基础医学 | 2963篇 |
口腔科学 | 428篇 |
临床医学 | 1820篇 |
内科学 | 3198篇 |
皮肤病学 | 342篇 |
神经病学 | 1739篇 |
特种医学 | 882篇 |
外科学 | 2644篇 |
综合类 | 115篇 |
一般理论 | 2篇 |
预防医学 | 939篇 |
眼科学 | 576篇 |
药学 | 1202篇 |
中国医学 | 56篇 |
肿瘤学 | 908篇 |
出版年
2023年 | 69篇 |
2022年 | 117篇 |
2021年 | 277篇 |
2020年 | 155篇 |
2019年 | 295篇 |
2018年 | 338篇 |
2017年 | 284篇 |
2016年 | 344篇 |
2015年 | 365篇 |
2014年 | 499篇 |
2013年 | 722篇 |
2012年 | 989篇 |
2011年 | 984篇 |
2010年 | 665篇 |
2009年 | 626篇 |
2008年 | 979篇 |
2007年 | 1055篇 |
2006年 | 1062篇 |
2005年 | 1087篇 |
2004年 | 885篇 |
2003年 | 877篇 |
2002年 | 862篇 |
2001年 | 194篇 |
2000年 | 160篇 |
1999年 | 191篇 |
1998年 | 193篇 |
1997年 | 153篇 |
1996年 | 144篇 |
1995年 | 151篇 |
1994年 | 117篇 |
1993年 | 119篇 |
1992年 | 94篇 |
1991年 | 91篇 |
1990年 | 76篇 |
1988年 | 69篇 |
1985年 | 68篇 |
1984年 | 84篇 |
1983年 | 64篇 |
1982年 | 90篇 |
1981年 | 80篇 |
1933年 | 97篇 |
1932年 | 93篇 |
1931年 | 81篇 |
1930年 | 83篇 |
1929年 | 76篇 |
1928年 | 78篇 |
1927年 | 69篇 |
1926年 | 80篇 |
1924年 | 77篇 |
1923年 | 76篇 |
排序方式: 共有10000条查询结果,搜索用时 19 毫秒
11.
12.
13.
Jing‐Ping Zhang Limin Zheng Jiang‐Hai Wang Karl‐Eric Magnusson Xin Liu 《Phytotherapy research : PTR》2009,23(6):844-850
Ganoderma sinensis has been used widely in Oriental countries for the prevention and treatment of various diseases including cancer. Previous studies have shown that the lipid extract from Ganoderma exhibits direct cytotoxicity against tumor cells. Here, it is reported that the lipid extract from germinating G. sinensis spores, at lower concentrations that have no direct tumoricidal activity, induce potent antitumor immune responses in human monocytes/macrophages. Upon stimulation with the lipid extract, monocytes/macrophages exhibited markedly increased production of proinflammatory cytokines and surface expression of costimulatory molecules. Conditioned medium from stimulated cells effectively suppressed the growth of tumor cells. Apparently, the lipid extract triggered macrophage activation via a mechanism different from that associated with LPS. Moreover, it was observed that the lipid extract could partially re‐establish the antitumor activity of the immunosuppressive tumor‐associated macrophages. These results indicated that in addition to its direct tumoricidal activity, the lipid extract from G. sinensis spores could exert antitumor activity by stimulating the activation of human monocytes/macrophages. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
14.
Werner Benzer Marion Platter Neil B Oldridge Helmut Schwann Kurt Machreich Werner Kullich Karl Mayr Axel Philippi Alfred Gassner Jakob D?rler Stefan H?fer 《European journal of cardiovascular prevention and rehabilitation》2007,14(3):441-447
BACKGROUND: An objective of exercise-based cardiac rehabilitation is improvement in patient-reported outcomes such as health-related quality of life as well as anxiety and depressive symptoms. There are no direct comparisons of the effectiveness of inpatient and outpatient exercise-based cardiac rehabilitation programmes on patient-reported outcomes. METHODS: In this non-randomized study we collected patient-reported outcomes data with the MacNew Heart Disease health-related quality of life questionnaire and the Hospital Anxiety and Depression Scale at baseline, 1 month and again 3 months after admission to exercise-based cardiac rehabilitation in a cohort of 216 consecutive patients enrolled either in a 4-week inpatient exercise-based cardiac rehabilitation (n=62) or a 3-month outpatient exercise-based cardiac rehabilitation (n=87) and in a usual care group (n=67) to document the natural course in patient-reported outcome variables without exercise-based cardiac rehabilitation. RESULTS: Although MacNew health-related quality of life scores improved more with inpatient than outpatient exercise-based cardiac rehabilitation by month 1, the improvement was still significant in both groups at month 3 and also in the usual care group when compared to baseline. The health-related quality of life scores in the inpatient group, however, decreased between month 1 and 3 whereas they continued to improve in the outpatient group. The significant reduction in both anxiety and depressive symptoms in both exercise-based cardiac rehabilitation groups by month 1 was maintained at month 3 only with outpatient exercise-based cardiac rehabilitation. No significant changes over the 3 months were observed in the usual care group. CONCLUSION: Significant improvements of 1-month patient-reported outcomes are achieved in patients attending inpatient as well as outpatient exercise-based cardiac rehabilitation when compared with no exercise-based cardiac rehabilitation. In contrast to inpatient exercise-based cardiac rehabilitation, however, outpatient exercise-based cardiac rehabilitation leads to a further improvement of patient-reported outcomes. These results suggest that, if patients have to be admitted for inpatient exercise-based cardiac rehabilitation, this programme should be followed by an outpatient exercise-based cardiac rehabilitation to further improve and stabilize these patient-reported outcome variables. 相似文献
15.
16.
Ma?gorzata Pawelec-Wojtalik Ludwig Karl von Segesser Ma Liang Dorota Bukowska 《European journal of cardio-thoracic surgery》2005,27(4):714-716
Growing experience in interventional cardiology leads to the use of large diameter of vascular equipment. In some instances, the so-called hybrid procedures are performed. After performing the interventional procedure, the opening in ventricular wall is closed surgically. Our intention was to check if the MVSDO can be used to close the perforation in the heart after the interventional cardiology procedure performed through the left ventricular (LV) free wall. In three pigs under general anesthesia, the heart was exposed through a small substernal incision. The LV was punctured and an 18F sheath was introduced into the LV. A 14 mm MVSDO was inserted through the 10F Delivery System. Using both the echocardiographic and angiographic guidance, the MVSDO was placed on the LV wall to close the opening in the LV. Time and volume of bleeding was recorded. In all cases the occluder was successfully placed closing the opening, bleeding observed after deployment of occluder lasted for approximately 2 min. We think MVSD occluder can be used to close the LV free wall perforation after hybrid interventional cardiac procedure. Early bleeding through MVSDO might be resolved by the manufacturing of new occluder with better sealing properties. 相似文献
17.
18.
Guo-Lin Wei Juri Melnik Jing-Li Luo Alan R. Sanger Karl T. Chuang 《Journal of electroanalytical chemistry (Lausanne, Switzerland)》2005,575(2):183-193
The performances of three widely different cathode materials (Pt, strontium-doped lanthanum manganite (LSM), and NiO) have been compared for use with proton conducting Li2SO4–Al2O3 composite electrolyte, using H2S–air and H2–air fuel cells operating at 600 °C. Surface analysis and electrochemical techniques were used to characterize fresh and used electrode materials. Pt or LSM cathodes each became covered with Li2SO4 and Al2O3 and, as a consequence, the fuel cells showed poor performance. In contrast, the NiO cathode catalyst did not become covered with Li2SO4 and good fuel cell performance was achieved. Exceptionally good current densities of over 100 mA/cm2 and power densities of over 30 mW/cm2 were obtained for H2S–air fuel cells having Mo–Ni–S anode catalysts. Slight agglomeration of NiO particles during fuel cell operation had only a minor effect on performance. 相似文献
19.
Andrea Bernatowicz Uwe Kdel Karl Frei Adriano Fontana Hans-walter Pfister 《Journal of neuroimmunology》1995,60(1-2):53-61
Recent studies using a rat model of pneumococcal meningitis have shown that nitric oxide synthase (NOS) inhibitors greatly attenuated microvascular changes and brain edema formation. The site of NO production during bacterial meningitis is unknown. In this study we tested whether primary astrocyte cultures from neonatal rat cortex can be induced to release NO upon stimulation with pneumococci. NO production was assessed by measuring nitrite in the cell culture supernatant using the Griess reaction. Stimulation with heat-killed unencapsulated pneumococci (HKP) increased nitrite concentrations in astrocyte culture supernatants in a dose-dependent fashion. Administration of AT-nitro-L-arginine (L-NA), aminoguanidine, L-canavanine, cycloheximide, and dexamethasone prevented the increase in nitrite concentrations. Addition of L-arginine, but not of o-arginine, partially reversed the inhibitory effect of L-NA. Administration of SOD increased nitrite accumulation. Moreover, at 72 h after stimulation with heat-killed pneumococci (107 cfu/ml) astrocytes showed an inducible NOS-like immunoreactivity. Accumulation of nitrite was also observed when rat cerebellar neurons and microglia were stimulated with HKP, whereas there was only a slight increase of nitrite in media of rat C6 glioma cells, but no increase of nitrite when the human glioblastoma cell line LN-229 was stimulated with HKP. There was a stronger increase in nitrite levels when astrocytes from Lewis rats were used compared to that from Wistar rats. In conclusion, our study indicates that astrocytes, neurons and microglia are inducible for NO production upon stimulation with pneumococci. 相似文献
20.
Brenda D. Jamerson Pharm.D. George E. Dukes Pharm.D. Kim L.R. Brouwer Pharm.D. Ph.D. Karl H. Dorm Ph.D. John A. Messenheimer M.D. J. Robert Powell Pharm.D. 《Pharmacotherapy》1994,14(1):47-52
Study Objective . To compare the frequency, severity, and time course of venous irritation after administration of a single intravenous dose of phenytoin with an equimolar dose of fosphenytoin, a water-soluble phenytoin prodrug. Design . Randomized, double-blind, two-period, crossover study. Setting . University hospital clinical research unit. Patients . Twelve healthy volunteers within 15% of ideal body weight and with no clinically significant abnormalities on physical examination, medical history, or laboratory assessment. Interventions . Volunteers randomly received a 30-minute infusion of phenytoin sodium 250 mg (250 mg/5 ml) or an equimolar dose of fosphenytoin 375 mg (375 mg/5 ml). Subjects returned for the crossover treatment 14–21 days later. Measurements and Main Results . Subjects assessed venous irritation (pain, burning, itching), and investigators evaluated phlebitis (erythema, swelling, tenderness), induration, exudation, and cording. Phenytoin was associated with a significantly higher degree of pain at the infusion site in all subjects and a significant degree of phlebitis in eight subjects (p<0.05); cording occurred in six subjects. The time course of phenytoin-induced phlebitis was bimodal. Erythema and tenderness were prominent at the end of the infusion and again at 24 hours. Cording was first noted between 24 hours and 1 week after infusion. In contrast, fosphenytoin was associated with mild pain in two subjects, one incident of phlebitis, and no erythema or cording. Conclusions . Fosphenytoin administration resulted in significantly less venous irritation and phlebitis compared with an equimolar dose of phenytoin. The clinical use of this water-soluble phenytoin prodrug should minimize the frequency and severity of infusion-site reactions and should allow convenient, rapid, intravenous administration of drug, undiluted or admixed with intravenous solutions. 相似文献