全文获取类型
收费全文 | 1493篇 |
免费 | 77篇 |
国内免费 | 75篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 53篇 |
妇产科学 | 40篇 |
基础医学 | 148篇 |
口腔科学 | 51篇 |
临床医学 | 173篇 |
内科学 | 381篇 |
皮肤病学 | 43篇 |
神经病学 | 77篇 |
特种医学 | 265篇 |
外科学 | 156篇 |
综合类 | 30篇 |
一般理论 | 1篇 |
预防医学 | 68篇 |
眼科学 | 29篇 |
药学 | 67篇 |
中国医学 | 3篇 |
肿瘤学 | 59篇 |
出版年
2023年 | 7篇 |
2022年 | 8篇 |
2021年 | 6篇 |
2020年 | 11篇 |
2019年 | 11篇 |
2018年 | 21篇 |
2017年 | 14篇 |
2016年 | 17篇 |
2015年 | 26篇 |
2014年 | 29篇 |
2013年 | 36篇 |
2012年 | 36篇 |
2011年 | 37篇 |
2010年 | 50篇 |
2009年 | 64篇 |
2008年 | 38篇 |
2007年 | 70篇 |
2006年 | 37篇 |
2005年 | 37篇 |
2004年 | 34篇 |
2003年 | 30篇 |
2002年 | 34篇 |
2001年 | 46篇 |
2000年 | 40篇 |
1999年 | 24篇 |
1998年 | 88篇 |
1997年 | 78篇 |
1996年 | 65篇 |
1995年 | 60篇 |
1994年 | 48篇 |
1993年 | 49篇 |
1992年 | 33篇 |
1991年 | 24篇 |
1990年 | 30篇 |
1989年 | 41篇 |
1988年 | 39篇 |
1987年 | 41篇 |
1986年 | 26篇 |
1985年 | 28篇 |
1984年 | 23篇 |
1983年 | 22篇 |
1982年 | 22篇 |
1981年 | 16篇 |
1980年 | 19篇 |
1979年 | 13篇 |
1978年 | 11篇 |
1977年 | 22篇 |
1976年 | 20篇 |
1975年 | 14篇 |
1974年 | 6篇 |
排序方式: 共有1645条查询结果,搜索用时 15 毫秒
21.
22.
23.
Cloning and expression of the gene involved in Sanfilippo B syndrome (mucopolysaccharidosis III B) 总被引:4,自引:1,他引:4
Sanfilippo B syndrome is caused by a deficiency of alpha-N-
acetylglucosaminidase, a lysosomal enzyme involved in the degradation of
heparan sulphate. Accumulation of the substrate in lysosomes results in
degeneration of the central nervous system with progressive dementia often
combined with hyperactivity and aggressive behaviour. In order to clone the
deficient gene, we purified the enzyme from human placenta and obtained
amino acid sequence information. Alignment of one of the CNBr generated
internal peptides to sequence from the database revealed the chromosomal
location of the gene in the 5' upstream flanking region of the gene for
17-beta-hydroxysteroid-dehydrogenase at 17q21.1. The available DNA sequence
was used to clone the cDNA coding for alpha-N- acetylglucosaminidase and
analyse its gene structure. The gene is fully contained in the 5' upstream
flanking region of the gene for 17-beta- hydroxysteroid-dehydrogenase and
interrupted by five introns. The cDNA clone has a length of 2575 bp and
encodes a protein of 743 amino acids. Chinese hamster ovary cells
transfected with the cDNA construct show alpha-N-acetylglucosaminidase
activity about 17-fold over background. This will allow correction studies
with NAG deficient Sanfilippo B cell lines and facilitate the development
of enzyme replacement therapy for these patients.
相似文献
24.
Zaeem Lone Prithvi B. Murthy JJ Haijing Zhang Kyle J. Ericson Lewis Thomas Abhinav Khanna Georges-Pascal Haber Byron H. Lee 《Urologic oncology》2021,39(5):301.e1-301.e9
PurposeRenal function outcomes following robot-assisted radical cystectomy (RARC) have not been well established. We sought to compare long-term renal function outcomes between open radical cystectomy, RARC with extracorporeal urinary diversion and intracorporeal urinary diversion at a high volume institution.Materials and MethodsWe retrospectively reviewed our institutional bladder cancer database for patients who underwent RC from 2010 to 2019 with pre-operative estimated glomerular filtration rate (eGFR) > 45 ml/min/1.73m2. Changes in renal function were assessed through locally weighted scatter plot smoothing and comparison of median eGFR between surgical groups. Chronic Kidney Disease Stage 3B was defined as eGFR < 45 ml/min/1.73m2. Renal function decline was defined as a ≥10 ml/min/1.73m2 drop in eGFR. Kaplan Meier method with log-rank was used to compare CKD 3B-free survival and renal function decline. Cox Proportional Hazards model was used to identify predictors of CKD 3B.ResultsSix hundred and forty four patients were included with median follow-up of 32 months (IQR 12–56). Preoperative characteristics were similar among the groups with no differences in median pre-operative eGFR (ORC: 74.6, extracorporeal urinary diversion: 74.3, intracorporeal urinary diversion: 71.6 ml/min/1.73m2, P = 0.15). Median postoperative eGFR on follow up was not different between groups (P = 0.56). 33% of patients developed CKD 3B. There were no differences in CKD 3B-free survival by surgical approach (P = 0.23) or urinary diversion (P = 0.09). 64% of patients experienced renal function decline with a median time of 2.4 years (P 0.23). Predictors of CKD were pathologic T3 disease or greater (HR: 1.77, P = 0.01), ureteroenteric anastomotic stricture (HR: 2.80, P < 0.001), preoperative CKD Stage 2 (HR: 1.81, P =0.02), and preoperative CKD Stage 3A (HR: 5.56, P < 0.001).ConclusionRenal function decline is common after RC. Tumor stage, pre-operative eGFR, and ureteral stricture development, not surgical approach, influence renal function decline. 相似文献
25.
Andry Perrin Wulphert Venderink Michael A. Patak Claudius Möckel Jean-Luc Fehr Patrice Jichlinski Beat Porcellini Ilaria Lucca Jurgen Futterer Massimo Valerio 《Urologic oncology》2021,39(5):297.e9-297.e16
ObjectivesTo evaluate the utility of in-bore multiparametric magnetic resonance-guided biopsy of the prostate (IB) in patients with visible lesion/s and previous negative software-based multiparametric magnetic resonance imaging/ultrasonography fusion-targeted biopsy of the prostate (FTB).Patients and methodsWe retrospectively analysed prospectively maintained database including consecutive men undergoing IB from March 2013 to October 2017 in 2 European centres expert in this procedure. We selected men with the following criteria: No previous treatment for prostate cancer (CaP), multiparametric magnetic resonance imaging (mpMRI) lesion(s) PIRADS score ≥ 3, FTB showing no clinically significant cancer (csCaP), and subsequent IB. Patient's characteristics, mpMRI findings, biopsy technique, and histopathological results were extracted. The primary outcome was to determine the detection rate of csCaP, defined as any Gleason pattern ≥ 4. A multivariable analysis was performed to identify predictors of positive findings at IB.ResultsFifty-three men were included. Median age was 68 years (interquartile range [IQR] 64–68), median Prostate-Specific Antigen (PSA) was 7.6 ng/ml (IQR 5.2–10.9), and median prostate volume was 59 ml (IQR 44–84). Fifty-six lesions with PIRADS score 3 in 9 cases (16%), 4 in 30 cases (54%), and 5 in 17 cases (30%) were detected. FTB was performed in all cases using a transrectal approach with 3 different platforms (Toshiba, Koelis, and Artemis). Median time between FTB and IB was 3 months (IQR 1–7). A median of 2 cores per lesion were collected with IB (IQR 2–3). No cancer, clinically insignificant and clinically significant cancer were found in 33 (59%), 9 (16%), and 14 (25%) targeted lesions, respectively. Median maximum cancer core length and maximum positive percentage were 9 mm (3–13) and 55% (21%–80%). The only predictor of csCaP on IB was prostate volume (P = 0.026) with an ideal cut-off at 70 ml.ConclusionOne in 4 patients with previous negative FTB, IB was able to detect csCaP. According to this study, IB would be of particularly useful in patients with large glands. 相似文献
26.
Fehr M.K.; Madsen S.J.; Svaasand L.O.; Tromberg B.J.; Eusebio J.; Berns M.W.; Tadir Y. 《Human reproduction (Oxford, England)》1995,10(11):3067-3072
Photodynamic therapy is currently being evaluated as a minimallyinvasive procedure for endometrial ablation not requiring anaesthesia.Light penetration depths at 630, 660 and 690 nm and the optimalconfiguration of intrauterine light-diffusing fibres were determinedin 14 human uteri to assist in the design of a light intrauterinedevice. Post-menopausal ex-vivo uteri showed a significantlylower light penetration depth than pre-menopausal uteri. Witha single central diffusing fibre inserted, the fluence ratemeasured in the uterine wall at the most remote point of thecavity decreased to 1.1 ± 0.4% of that measured at closestproximity, whereas it decreased to only 40.0 ± 9.0% withthree fibres. Distension of the uterine cavity with 2 ml ofan optically clear fluid increased the fluence rate at the fundusbetween the fibres at a depth of 2 mm by a factor of 4. We concludethat in normal-sized pre-menopausal uterine cavities, threediffusing fibres will deliver an optical dose above the photodynamicthreshold level at a depth of 4 mm, even in the most remoteareas, in <30 min without causing thermal damage. For distortedand elongated cavities, either slight distension of the cavityor the insertion of a fourth diffusing fibre is required. 相似文献
27.
P Rock C Beattie A W Kimball D P Nyhan B B Chen D M Fehr S A Derrer S D Parker P A Murray 《Anesthesiology》1990,73(6):1186-1197
The authors' objectives were as follows: 1) to characterize for the first time the relationship between whole body O2 delivery (DO2) and O2 consumption (VO2) in adult conscious dogs; and 2) to asses the effects of the inhalational anesthetic, halothane, on that relationship. DO2 was varied over a wide range in chronically instrumented dogs by gradual inflation and deflation of a hydraulic occluder implanted around the thoracic inferior vena cava to alter venous return and cardiac output. VO2 was measured at different values of DO2 in dogs in the fully conscious state and again during halothane anesthesia. A "binning" technique indicated that halothane decreased VO2 (P less than 0.01) at any given value of DO2 over a broad range of VO2. A two-line piecewise linear regression analysis technique indicated that halothane decreased (P less than 0.01) the critical O2 delivery (COD) from 20 +/- 3 to 10 +/- 1 ml.kg-1.min-1 and increased (P less than 0.01) O2 extraction at COD from 31 +/- 3 to 40 +/- 2%. However, the DO2-VO2 plots measured in both conscious and halothane-anesthetized dogs did not exhibit a discrete discontinuity but rather were closely fit (correlation coefficient = 0.98) by an exponential equation of the following form: O2 extraction = B1.(1 - exp (-DO2/B2))/DO2, where B1 is the delivery-independent estimate of VO2 and B2 is the "delivery constant," i.e., the DO2 associated with a VO2 equal to 63% of B1. Halothane decreased B1 (P less than 0.01) from 5.3 +/- 0.1 to 3.9 +/- 0.1 ml.kg-1.min-1 and decreased B2 (P less than 0.01) from 5.6 +/- 0.3 to 3.6 +/- 0.3 ml.kg-1.min-1 compared with that measured in conscious dogs. Thus, compared with the conscious state, halothane anesthesia alters the fundamental relationship between DO2 and VO2 and may have a beneficial effect on tissue oxygenation at low values of DO2. 相似文献
28.
下消化道出血221例分析 总被引:4,自引:2,他引:2
0 引言 下消化道出血是消化科的常见病 ,是指十二指肠空肠移行部 ,屈氏韧带以下的小肠和大肠疾病引起的肠道出血 .有人认为一般不包括痔和肛裂出血 [1 ] .临床最常见为慢性出血 ,但有时出血量大危及生命 ,需要做紧急处理 ,现将我院1992 - 0 1/ 1999- 0 8门诊及病房收治的 2 2 1例下消化道出血进行分析 ,报告如下 :1 临床资料 男 12 0例 ,女 10 1例 ,年龄 14~ 72 (平均 42 )岁 ,病程 16 h~ 10 a.患者分别以脓血便、暗红色血便、鲜血便或果酱色血便为主诉前来就诊 ,其中有休克症状的大出血者6例 .血 Hb<110 g·L- 1 40例 ,<80 g·L- 1… 相似文献
29.
1 病例报告 女 ,45岁 ,因吞咽困难 16 mo伴发热 15 d,于1999- 0 7- 12入院 .于 16 mo前与人争吵后出现吞咽困难 ,以进食馒头、面条为著 ,剑突下有时出现梗噎感 ,随即呕吐 ,呕出所进食物及粘液 ,情绪波动可诱发症状加重 ,伴食欲减退、返酸 .15 d前无诱因出现不规则发热 ,T38~ 39℃ ,上腹痛加重 ,全身酸困不适 ,乏力、头晕、消瘦 .追问病史 ,患者 5 a前双手、足疼痛麻木 ,尤以受凉、精神刺激后明显 ,手指初发白 ,继而发紫 ,变红 ,且麻木疼痛加重 ,手足小关节渐僵硬、畸形 .曾到多家医院就诊 ,诊断 :“雷诺病、类风湿性关节炎”.2 a前出现… 相似文献
30.
R Fehr 《Epidemiology (Cambridge, Mass.)》1999,10(5):618-625
"Environmental impact assessment" denotes the attempt to predict and assess the impact of development projects on the environment. A component dealing specifically with human health is often called an "environmental health impact assessment." It is widely held that such impact assessment offers unique opportunities for the protection and promotion of human health. The following components were identified as key elements of an integrated environmental health impact assessment model: project analysis, analysis of status quo (including regional analysis, population analysis, and background situation), prediction of impact (including prognosis of future pollution and prognosis of health impact), assessment of impact, recommendations, communication of results, and evaluation of the overall procedure. The concept was applied to a project of extending a waste disposal facility and to a city bypass highway project. Currently, the coverage of human health aspects in environmental impact assessment still tends to be incomplete, and public health departments often do not participate. Environmental health impact assessment as a tool for health protection and promotion is underutilized. It would be useful to achieve consensus on a comprehensive generic concept. An international initiative to improve the situation seems worth some consideration. 相似文献