全文获取类型
收费全文 | 17081篇 |
免费 | 547篇 |
国内免费 | 32篇 |
专业分类
耳鼻咽喉 | 914篇 |
儿科学 | 503篇 |
妇产科学 | 1082篇 |
基础医学 | 2121篇 |
口腔科学 | 99篇 |
临床医学 | 914篇 |
内科学 | 3650篇 |
皮肤病学 | 190篇 |
神经病学 | 1872篇 |
特种医学 | 290篇 |
外科学 | 1239篇 |
综合类 | 56篇 |
一般理论 | 1篇 |
预防医学 | 1245篇 |
眼科学 | 552篇 |
药学 | 2401篇 |
中国医学 | 39篇 |
肿瘤学 | 492篇 |
出版年
2023年 | 82篇 |
2022年 | 292篇 |
2021年 | 450篇 |
2020年 | 168篇 |
2019年 | 282篇 |
2018年 | 540篇 |
2017年 | 374篇 |
2016年 | 399篇 |
2015年 | 353篇 |
2014年 | 598篇 |
2013年 | 883篇 |
2012年 | 1050篇 |
2011年 | 1294篇 |
2010年 | 660篇 |
2009年 | 295篇 |
2008年 | 803篇 |
2007年 | 1155篇 |
2006年 | 1219篇 |
2005年 | 1183篇 |
2004年 | 1278篇 |
2003年 | 1250篇 |
2002年 | 1034篇 |
2001年 | 460篇 |
2000年 | 499篇 |
1999年 | 303篇 |
1998年 | 105篇 |
1997年 | 27篇 |
1996年 | 16篇 |
1995年 | 26篇 |
1994年 | 14篇 |
1993年 | 14篇 |
1992年 | 17篇 |
1991年 | 17篇 |
1990年 | 30篇 |
1988年 | 17篇 |
1987年 | 21篇 |
1986年 | 21篇 |
1985年 | 24篇 |
1984年 | 20篇 |
1983年 | 24篇 |
1982年 | 23篇 |
1981年 | 33篇 |
1980年 | 22篇 |
1979年 | 24篇 |
1978年 | 32篇 |
1977年 | 30篇 |
1976年 | 17篇 |
1975年 | 25篇 |
1974年 | 13篇 |
1973年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
This paper presents results of an in vitro investigation of the optical anisotropy of the human cornea. Computer controlled imaging polarimetry and the Jones formalism were used to investigate the distribution of the birefringence and the azimuth angle across the surface of 12 corneas taken from the corneal bank. Each map of the birefringence and the azimuth angle has no rotational symmetry and is different for each cornea. The minimal value of the birefringence always appears in the corneal centre and varies from 9 to 43 degrees for different corneas. Birefringence of the cornea increases monotonically more than one order in the direction of the corneal periphery. Close to the centre of the cornea the azimuth angle is almost constant and varies significantly away from the optical part of the cornea. 相似文献
22.
Jaros?aw Wysocki 《Skull base》2005,15(2):99-106
One hundred temporal bones obtained from forensic autopsies were dissected to expose injured structures. Longitudinal fractures were present in 82%, transverse fractures in 11%, and mixed fractures in 7% of the cases. Facial canal injuries were present in almost half of the bones with longitudinal fractures (36/82), although cuts of the facial nerve stem were rarely encountered. Damages to the facial canal associated with longitudinal fractures were most frequently seen in the region of the geniculum. However, transverse fractures with facial canal involvement (7/11) most frequently occurred in the labyrinthine portion, causing a complete cut of the facial nerve. Injuries to the jugular bulb were also common (21/100) and associated with all types of temporal bone fractures. Observed damages to the auditory ossicles included disconnection of their joints or fractures of the malleus or stapes. Fractures of the incus were not observed. Injuries to the carotid canal were common (52/100), although an injury to the arterial wall was observed in only one specimen. The frequency and nature of damage in temporal bone fractures strictly reflect the type of fracture, especially in terms of facial nerve disorders: the most serious damage is observed with fractures that involve the otic capsule. 相似文献
23.
Jacek Semenowicz Bogdan Koczy Przemys?aw Czuma Bart?omiej Pijet Tomasz Olszewski Roman Walo 《Chirurgia narzadów ruchu i ortopedia polska》2007,72(1):33-36
The Avantage double mobility press-fit cup was devised by Dr. Bousquet in the 70's to bring reasonable response to a problem of recurrent dislocation after total hip arthroplasty. The cup is attached to the femoral head by a bipolar polyethylene liner. The polyethylene liner moves freely inside a shiny--polished metal cup. The angular range of motion before impingement is increased by the mobility of the liner. The double connection (cup-liner, liner-head) reduces the stress on the metal cup and improve the stability of the prosthesis. The solution has proved to be efficient in reducing dislocation risk and maintains at the same time the appropriate range of motion. Between January 2004 and November 2005, 113 hip arthroplasties in 108 women with use of the double mobility cup were performed. The cemented version of the Avantage cup was inserted in 15 patients (mean age--76.9 years). Uncemented, HA coated implant was used in 98 patients (with mean age of 55 years). The mean follow-up was 20.4 months. No one patient was lost to follow-up. No postoperative dislocation was observed during follow-up. There was no unwanted leg lengthening greater than 1 cm. The Avantage cup may be indicated in any primary total hip arthroplasty especially in those with increased risk of postoperative dislocations. This cup enables a correct balance of the hip without a need of the unwanted lengthening of the leg. 相似文献
24.
Mieczysaw Pokorski Zdzisaw Matysiak Magdalena Marczak Robert P. Ostrowski Andrzej Kapuciski Iwona Matuszewska Marianna Kaska Zbigniew Czarnocki 《Drug development research》2003,60(3):217-224
N‐acyl‐dopamines are a novel class of biologically active lipids that have recently been identified in the brain and have the potential to interact with neural signaling pathways. This study seeks to determine the ability of N‐oleoyl‐dopamine, a synthetic amide of oleic acid and dopamine, to cross the blood brain barrier. We determined the tissue content of radioactivity in selected brain regions, in a short‐run study design, following injections of [3H]N‐oleoyl‐dopamine (0.4 µCi) into the internal carotid artery in the rat. These results were compared with intracarotid injections of [3H]dopamine and with intravenous injections of both radiolabeled compounds. The level of radioactivity was determined using liquid scintillation and was expressed as the percentage of its total dose injected per gram of tissue. We found that the 15‐min brain uptake of radioactivity, with no distinct regional variations, amounted to about 6% following the intracarotid [3H]N‐oleoyl‐dopamine, which was a significant 3–4‐fold increase over that following similar administration of [3H]dopamine. Intravenous injections of [3H]N‐oleoyl‐dopamine gave a much smaller yield of radioactivity in brain tissue samples which was still severalfold greater than that for intravenous [3H]dopamine. Qualitative thin‐layered chromatography screening showed the presence of unchanged N‐oleoyl‐dopamine in the brain following injections. We conclude that N‐oleoyl‐dopamine has an appreciable ability to cross the blood‐brain barrier, which contrasts the limited transfer of dopamine alone. N‐oleoyl‐dopamine might exert physiological effects due to its known affinity for the central vanilloid receptors or to better satisfying the brain tissue demand for dopamine. The study suggests a potential pharmacological role for N‐oleoyl‐dopamine delivered exogenously in helping regulate the brain function. Drug Dev. Res. 60:217–224, 2003. © 2003 Wiley‐Liss, Inc. 相似文献
25.
A. Dmoszyńska-Giannopoulou L. Janicka B. Sokołowska A. Ksi⇂żek G. Orłowska K. Janicki 《International urology and nephrology》1990,22(6):561-566
In 30 patients on chronic haemodialysis treatment the platelet activity and function were studied before and during antiplatelet
therapy with alpha-tocopherol and sulphinpyrazone. In both kinds of treatment a significant decrease of ADP-induced and spontaneous
aggregation was observed. Sulphinpyrazone exerts an inhibitory effect not only on platelet aggregation but also on platelet
factor 3 and provokes a significant prolongation of the bleeding time. 相似文献
26.
Anna Szymańska Elżbieta Korobowicz Wiesław Gołąbek 《European archives of oto-rhino-laryngology》2006,263(7):657-660
Nasopharyngeal angiofibromas occur predominantly in males in their puberty and adolescence; the incidence in other age groups and in women is exceptional. This report describes a case of a 57-year-old woman with nasopharyngeal angiofibroma presenting typical radiological findings in computed tomography, MR imaging and angiography. The tumour was successfully removed and histopathological examination confirmed the diagnosis. In 6 years follow-up the patient is free of symptoms. 相似文献
27.
Treatment of End-Stage Renal Disease in Central and Eastern Europe: Overview of Current Status and Future Needs 总被引:2,自引:0,他引:2
Bolesaw Rutkowski Aleksandru Ciocalteu Ljubica Djukanovic Istvan Kiss Aleksander Kovac Momir Polenakovic Zvonimir Puretic Rafail Rozental Maria Stanaityte Irina Tareyeva Vladimir Teplan Jeff Zavitz Krivoshiev Stefan & Kveder Rado 《Artificial organs》1998,22(3):187-191
The situation of end-stage renal disease (ESRD) patients in central and eastern Europe was very poor for many years during the so called socialistic era. Economical and political liberation resulted in the significant growth of renal replacement facilities in this region. The number of hemodialysis units increased significantly (56%) during the period 1990–1996, and the number of patients treated with this modality has risen by 75%. More dramatic progress was achieved in peritoneal dialysis. The number of units performing this method of renal replacement therapy (RTT) increased by 277% and the number of patients by more than 300%. Not only quantitative but also qualitative changes were observed. More modern hemodialysis machines installed in the vast majority of units allow for the performance of bicarbonate dialysis, controlled ultrafiltration, and sodium profile modeling. Also, a wider choice of biocompatible dialyzers has become available during the last few years. The number of centers performing renal transplantation has increased significantly, but the number of renal transplants has not followed this progress. Despite all the progress, further development of all RRT methods is necessary to achieve acceptance rates comparable to those observed in developed countries. 相似文献
28.
Tomasz Trojanowski Jerzy P ceszyński Krzysztof Turowski Stanisław Kamiński Igor Gościński Marian Reinfus Tadeusz Krzyszkowski Marek Pyrich Adam Bielawski Czesława Leszczyk Barbara Bendarzewska Andrzej Staszczak Halina Koźniewska 《Journal of neuro-oncology》1988,6(3):285-291
A prospective, randomized trial evaluates the effects of two postoperative treatment regimens on survival in 198 adult patients with supratentorial gliomas. All patients were irradiated with 6 000 rads after possibly radical removal of tumors. CCNU administration in the dosis of 100 mg/sq m of body surface every 6–8 weeks following surgery proved to have no significant effect on the survival of patients. The median survival time in patients receiving radiation therapy alone was 61±7 weeks, while in those receiving additional chemotherapy was 56±4 weeks. Tumor histological malignancy and patients age were found to be the only important prognostic factors, irrespective of the treatment modality.
Address for offprints: T Trojanowski, Department of Neurosurgery, Medical School, Jaczewskiego 8, 20-950 Lublin, Poland 相似文献
29.
Raman and infrared spectra were made of mercuryII, cadmium and aluminum benzoates To better understand the mechanism of toxic action of heavy metals, comparisons were made of the effects of mercuryI, mercuryII, leadII, cadmium barium, strontium, copperII, aluminum, ironIII zinc, magnesium, calcium, yttrium, lanthanumIII neodymiumIII, dysprosiumIII, luthetiumIII, lithium sodium, and potassium on the aromatic system of benzoic acid. Benzoic acid was considered to be model compound, representing a wide group of aromatic ligands present in enzymes. Oscillation (Raman, IR) and electronic (UV) spectroscopy methods were applied.Heavy toxic metals, particularly HgI, HgII, and PbII in contrast to Ca, Mg, Al, FeIII, Zn, Y, and LnIII perturb the aromatic system of benzoic acid by deforming the uniforming distribution of electron charges in the ring. 相似文献