全文获取类型
收费全文 | 25157篇 |
免费 | 1654篇 |
国内免费 | 135篇 |
专业分类
耳鼻咽喉 | 301篇 |
儿科学 | 545篇 |
妇产科学 | 474篇 |
基础医学 | 3506篇 |
口腔科学 | 647篇 |
临床医学 | 2150篇 |
内科学 | 5698篇 |
皮肤病学 | 338篇 |
神经病学 | 2404篇 |
特种医学 | 1001篇 |
外科学 | 3379篇 |
综合类 | 262篇 |
一般理论 | 48篇 |
预防医学 | 1936篇 |
眼科学 | 1158篇 |
药学 | 1594篇 |
中国医学 | 52篇 |
肿瘤学 | 1453篇 |
出版年
2023年 | 102篇 |
2022年 | 266篇 |
2021年 | 558篇 |
2020年 | 285篇 |
2019年 | 419篇 |
2018年 | 568篇 |
2017年 | 430篇 |
2016年 | 516篇 |
2015年 | 546篇 |
2014年 | 801篇 |
2013年 | 1053篇 |
2012年 | 1635篇 |
2011年 | 1680篇 |
2010年 | 986篇 |
2009年 | 909篇 |
2008年 | 1523篇 |
2007年 | 1582篇 |
2006年 | 1409篇 |
2005年 | 1462篇 |
2004年 | 1297篇 |
2003年 | 1222篇 |
2002年 | 1202篇 |
2001年 | 294篇 |
2000年 | 270篇 |
1999年 | 314篇 |
1998年 | 260篇 |
1997年 | 266篇 |
1996年 | 212篇 |
1995年 | 182篇 |
1994年 | 134篇 |
1993年 | 140篇 |
1992年 | 195篇 |
1991年 | 180篇 |
1990年 | 185篇 |
1989年 | 133篇 |
1988年 | 144篇 |
1987年 | 145篇 |
1986年 | 151篇 |
1985年 | 153篇 |
1984年 | 164篇 |
1983年 | 156篇 |
1982年 | 153篇 |
1981年 | 174篇 |
1980年 | 146篇 |
1979年 | 123篇 |
1978年 | 110篇 |
1977年 | 108篇 |
1975年 | 112篇 |
1974年 | 101篇 |
1973年 | 120篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
R E Albert 《Environmental health perspectives》1997,105(9):940-948
Chemicals that were bioassayed by the National Toxicology Program (NTP) and that also produce allergic dermatitis (ACD) in humans were evaluated for their tumorigenic characteristics. The impetus for the study was that most contact sensitizers, i.e., those that produce ACD, and genotoxic carcinogens are chemically similar in that they are electrophilic, thereby producing adducts on macromolecules including protein and DNA. This similarity in chemical behavior suggests that many contact sensitizers might be environmental carcinogens. All of the published NTP bioassays by early 1996 that had both genotoxicity and carcinogenicity studies were included in this analysis. The NTP chemicals had been chosen for bioassay without regard to their ability to produce ACD. Of the 209 chemicals that were bioassayed, there were 36 (17%) that were known to be human contact sensitizers; about half of these were positive on tumor bioassays. The contact sensitizers differed from the NTP sample as a whole by having a proportionately larger number of nongenotoxic chemicals by the Ames Salmonella assay, presumably because more of them were selected on the basis of widespread usage rather than structural resemblance to known carcinogens. Compared to the nongenotoxic chemicals, the genotoxics were stronger carcinogens in that they had a higher incidence of positive tumor bioassays, with twice the number of organs in which tumors were induced. The nongenotoxic chemicals had a preference for tumor induction in parenchymal tissues in contrast to epithelial tissues. The contact sensitizers showed essentially the same characteristics as the whole NTP sample when stratified according to genotoxicity. Judging by the chemicals that were chosen primarily for their widespread use rather than for their structural resemblance to carcinogens, the addition of a test for contact sensitization to the Ames test as a screening tool would increase the tumorigenic detection efficiency by about 40% because of the nongenotoxic tumorigens. A ballpark estimate suggests that there could be several thousand contact sensitizers for humans in commercial use that are rodent tumorigens. 相似文献
32.
Papillitis and vasculitis of the arteria spinalis anterior as complications of hepatitis C reinfection after liver transplantation 总被引:1,自引:0,他引:1
T. Propst Albert Propst Karin Nachbaur I. Graziadei Hans Willeit Raimund Margreiter Wolfgang Vogel 《Transplant international》1997,10(3):234-237
It is well known that hepatitis C virus (HCV)-related chronic liver disease may be associated with various immunological
disorders including mixed cryoglobulinemia, which is accompanied by cutaneous vasculitis, arthralgias, membranoproliferative
glomerulonephritis, and neuropathy in association with cryoprecipitable immune complexes in serum. We describe here the first
case of central nervous system HCV infection with evidence of the virus in the cerebrospinal fluid in association with cryoglobulinemia
in a patient who developed recurrent episodes of papillitis and vasculitis of the arteria spinalis anterior after liver transplantation.
Received: 3 September 1996 Received after revision: 13 November 1996 Accepted: 6 December 1996 相似文献
33.
In order to overcome the problems of stress protection and pressure atrophy of bone, which are associated with the traditional plating technique, in Poland a modified type of plating, ZESPOL has been, developed. In this procedure, the plate is not screwed onto the surface of the bone, but is fixed above the bone by special platform screw bolts in a comblike construction. This paper describes an experimental biomechanical investigation, using cadaver tibia, which compares the stability of the ZESPOL principle with that of the traditionally applied autocompression plate (ACP). In order to make the system biomechanically comparable, instead of the original ZESPOL plates, which are different in dimension, an ACP was used that was specially adapted to fit the ZESPOL criteria. Compared to the ACP, the bending stability of the ZESPOL osteosynthesis was found to be significantly less. When the same stress was applied, the total bending capacity of the ZESPOL system was found to be between 9% and 1348% higher, depending on the position of the plate and the direction of the force applied. In addition, the gap of the osteotomy site was between 6% and 923% greater with the ZESPOL system. Deformation of the bone adjacent to the osteotomy site was more closely approximate to intact bone with ACP than with ZESPOL plate. Our evaluations show that the ZESPOL system has less bending stability than ACP, without having the advantage of a more physiological bone-bending curve. However, the stability of the new system can be regarded as being overall sufficient. 相似文献
34.
35.
Albert B. Zajko M.D. Klaus M. Bron William L. Campbell 《Cardiovascular and interventional radiology》1987,10(1):28-31
Biliary obstruction and multiple hepatic abscesses occurred in a patient after ligation of a segmental branch of the right
hepatic duct. The patient was successfully managed by transhepatic biliary drainage and balloon dilatation of an internal
fistula that developed between the ligated duct and a Roux limb of jejunum. Internal biliary fistulas may be dilated using
interventioanl radiologic techniques to permit nonobstructed bile flow. Implications for the nonsurgical treatment' of biliary
strictures are discussed. 相似文献
36.
Albert J. Moreno Allan L. Parker Peter Fredericks Gottlieb L. Turnbull 《European journal of nuclear medicine and molecular imaging》1986,12(5-6):309-310
A 58-year-old man with a pectus excavatum demonstrated a photon-deficient defect within the left lobe of the liver on liver-spleen scintigraphy using Tc-99m SCOL. Computed tomography of the liver clearly revealed the abnormal defect seen on the liver-spleen scan to be due to the pectus excavatum. This case confirms the impression that these skeletal aberrations may cause false-positive hepatic defects.The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense 相似文献
37.
Albert J Finestone Michael R Jacobs John A Cacciamani 《Clinical Interventions in Aging》2007,2(4):715-718
Critical to survival is the geriatric concept, allostasis, defined as the ability to achieve stability through change. It is appropriate that allostasis is an introduction to this commentary, which may partially apply to the medical and pharmacy profession as currently constituted. 相似文献
38.
Johanna Albert Leif Kindlund Barbro Nilvér Waldemar Gożdzik 《Central European Journal of Medicine》2006,1(2):162-171
Abstract: Background: The laryngeal mask airway (LMA) can be used in general anaesthesia without neuromuscular block. The
laryngeal tube (LT) is a new airway device with similar airway features as LMA. LT is provided with a distal cuff to prevent
regurgitation. In this study we compared the LMA and LT concerning patient and user aspects.
Methods: Sixty patients with ASA (American Society of Anestesiologists) score 1–2 scheduled for minor surgery were randomized
to be ventilated either through LMA or LT. After insertion, the number of insertion attempts, and “positioning” and “airway-assessment”
was evaluated. The patients reported on “sore throat” after 30 and 60 minutes and the day after anaesthesia.
Results: Gender and mean age were equal in both groups. The first insertion attempt was successful in 25 of 28 patients randomised
to LMA and in 23 of 27 patients randomised to LT. LMA was evaluated to be easier in “positioning” whereas no difference in
“sore throat” was reported.
Conclusion: We found no difference between the LMA and the LT in terms user and patient friendliness and safety. 相似文献
39.
N S Jones R M Irving G R Ford A Balakrishnan D M Albert 《Clinical otolaryngology and allied sciences》1992,17(2):141-145
A new endoscopic method of measuring the cross-sectional area of a subglottic stenosis is presented. The method was tested against existing techniques using a model. By standardizing the distance from the objective of the endoscope to the stenotic area we were able to measure the cross-sectional area using a graduated grid held against the video screen. This technique was then compared with the standard one of estimating the diameter of a stenosis from the external diameter of the bronchoscope which can be passed through the stenosis. The methods were found to be equally accurate in measuring the lumen diameter. However, when measuring the minimum cross-sectional area, three of five observers were significantly better (P less than 0.01) using the photometric method rather than the standard method (Wilcoxon's rank sum test for paired data). The photometric technique of measuring the cross-sectional area of the subglottis is easily performed, non-traumatic, and allows a visual record to be kept. 相似文献
40.