全文获取类型
收费全文 | 3413067篇 |
免费 | 249094篇 |
国内免费 | 10809篇 |
专业分类
耳鼻咽喉 | 45587篇 |
儿科学 | 112188篇 |
妇产科学 | 94451篇 |
基础医学 | 484040篇 |
口腔科学 | 94321篇 |
临床医学 | 320042篇 |
内科学 | 665440篇 |
皮肤病学 | 78087篇 |
神经病学 | 283112篇 |
特种医学 | 129057篇 |
外国民族医学 | 1047篇 |
外科学 | 499449篇 |
综合类 | 71981篇 |
现状与发展 | 6篇 |
一般理论 | 1343篇 |
预防医学 | 272539篇 |
眼科学 | 76552篇 |
药学 | 250120篇 |
12篇 | |
中国医学 | 7483篇 |
肿瘤学 | 186113篇 |
出版年
2019年 | 27655篇 |
2018年 | 38868篇 |
2017年 | 29650篇 |
2016年 | 33901篇 |
2015年 | 38284篇 |
2014年 | 52765篇 |
2013年 | 80418篇 |
2012年 | 107516篇 |
2011年 | 113811篇 |
2010年 | 68270篇 |
2009年 | 64680篇 |
2008年 | 105776篇 |
2007年 | 111997篇 |
2006年 | 113657篇 |
2005年 | 109095篇 |
2004年 | 104667篇 |
2003年 | 100917篇 |
2002年 | 97544篇 |
2001年 | 159185篇 |
2000年 | 163397篇 |
1999年 | 137954篇 |
1998年 | 40262篇 |
1997年 | 35765篇 |
1996年 | 35766篇 |
1995年 | 34511篇 |
1994年 | 31855篇 |
1993年 | 29964篇 |
1992年 | 108310篇 |
1991年 | 104734篇 |
1990年 | 101556篇 |
1989年 | 97725篇 |
1988年 | 89771篇 |
1987年 | 88038篇 |
1986年 | 83025篇 |
1985年 | 79333篇 |
1984年 | 59330篇 |
1983年 | 50647篇 |
1982年 | 30173篇 |
1981年 | 26904篇 |
1979年 | 52950篇 |
1978年 | 37600篇 |
1977年 | 31533篇 |
1976年 | 29783篇 |
1975年 | 31366篇 |
1974年 | 37424篇 |
1973年 | 35831篇 |
1972年 | 33482篇 |
1971年 | 31152篇 |
1970年 | 28837篇 |
1969年 | 27302篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
961.
Sami S Zoghbi H Umesha Shetty Masanori Ichise Masahiro Fujita Masao Imaizumi Jeih-San Liow Jay Shah John L Musachio Victor W Pike Robert B Innis 《Journal of nuclear medicine》2006,47(3):520-527
18F-2beta-Carbomethoxy-3beta-(4-chlorophenyl)-8-(2-fluoroethyl)nortropane (18F-FECNT), a PET radioligand for the dopamine transporter (DAT), generates a radiometabolite that enters the rat brain. The aims of this study were to characterize this radiometabolite and to determine whether a similar phenomenon occurs in human and nonhuman primate brains by examining the stability of the apparent distribution volume in DAT-rich (striatum) and DAT-poor (cerebellum) regions of the brain. METHODS: Two rats were infused with 18F-FECNT and sacrificed at 60 min. Extracts of brain and plasma were analyzed by high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometric (LC-MS) techniques. Two human participants and 3 rhesus monkeys were injected with 18F-FECNT and scanned kinetically, with serial arterial blood analysis. RESULTS: At 60 min after the injection of rats, 18F-FECNT accumulated to levels about 7 times higher in the striatum than in the cortex and cerebellum. The radiometabolite was distributed at equal concentrations in all brain regions. The LC-MS techniques identified N-dealkylated FECNT as a major metabolite in the rat brain, and reverse-phase HPLC detected an equivalent amount of radiometabolite eluting with the void volume. The radiometabolite likely was 18F-fluoroacetaldehyde, the product expected from the N-dealkylation of 18F-FECNT, or its oxidation product, 18F-fluoroacetic acid. The distribution volume in the cerebellum increased up to 1.7-fold in humans between 60 and 300 min after injection and 2.0 +/- 0.1-fold (mean +/- SD; n = 3) in nonhuman primates between 60 and 240 min after injection. CONCLUSION: An 18F-fluoroalkyl metabolite of 18F-FECNT originating in the periphery confounded the measurements of DAT in the rat brain with a reference tissue model. Its uniform distribution across brain regions suggests that it has negligible affinity for DAT (i.e., it is an inactive radiometabolite). Consistent with the rodent data, the apparent distribution volume in the cerebellum of both humans and nonhuman primates showed a continual increase at late times after injection, a result that may be attributed to entry of the radiometabolite into the brain. Thus, reference tissue modeling of 18F-FECNT will be prone to more errors than analysis with a measured arterial input function. 相似文献
962.
E. G. Paronikyan A. S. Noravyan Sh. F. Akopyan F. G. Arsenyan G. M. Stepanyan B. T. Garibdzhanyan 《Pharmaceutical Chemistry Journal》2006,40(6):293-295
Methods for the synthesis of new heterosystems of condensed thieno[3,2-d]-1,2,3-triazines on the basis of pyrido[2,3-b]thiophenes
have been developed. The antitumor activity of the synthesized compounds was studied and several compounds possessing low
toxicity and moderate antitumor activity were found.
__________
Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 40, No. 6, pp. 3–5, June, 2006. 相似文献
963.
964.
965.
966.
Jean-Sébastien Fallu Jürgen Rehm Emmanuel N. Kuntsche Esther Grichting Neerav Monga Edward M. Adlaf Susan J Bondy Gerhard Gmel 《Sozial- und Pr?ventivmedizin》2006,8(1):363-372
Volume and profile of alcohol consumption among students and classmates as predictors of aggression and victimization: a multilevel
analysis among Swiss adolescents
Objective:
To test the effects of the volume of alcohol consumption and drinking patterns on alcohol-related aggression and victimization, both at the individual and class levels. 相似文献967.
968.
969.
Palat Balachandran M.S. M.Ch. Shaleen Agarwal M.S. M.Ch. Narendra Krishnani M.D. Chandra M. Pandey Ph.D. Ashok Kumar M.S. M.Ch. Sadiq S. Sikora M.S. Rajan Saxena M.S. Vinay K. Kapoor M.S. 《Journal of gastrointestinal surgery》2006,10(6):848-854
The aim of this study was to examine the predictors of long-term survival (>24 months) in patients with gall bladder cancer.
A retrospective review of 117 cases of gall bladder cancer resected between 1989 and 2000. The resections included 80 simple
cholecystectomies and 37 extended procedures. Patients with survival >24 months (n=44) were compared with those having survival
<24 months (n=73) for 17 prognostic factors. Overall median survival was 16 months with a 5-year survival of 27%. T status
(P=.000) and adjuvant chemoradiotherapy (P=.001) were independent predictors of long-term survival. Survival advantage was
seen in T3N+ve disease (P=.007) with extended procedures. Complete (R0) resection was attained in 30 patients with a 5-year
survival advantage of 30% as compared with incomplete (R1) resection (P=.0002). Adjuvant chemoradiotherapy improved survival
in simple cholecystectomy group (P=.0008) but no advantage was seen after extended procedures. Stage III (P=.001) and node-positive
disease (P=.0005) had significant benefit with adjuvant therapy. Poor differentiation and vascular invasion were associated
with poor long-term survival. R0 resection was associated with prolonged survival. Extended procedures improved survival in
patients with T3N+ve disease. Addition of chemoradiotherapy made significant improvement in long-term survival in stage III
and node-positive lesions and in patients undergoing simple cholecystectomy. R0 resection predicted long-term survival in
gall bladder cancer. T3 N+ve disease had better survival after extended procedures. Adjuvant chemoradiotherapy improved survival
in stage III and node-positive disease. Poor differentiation and vascular invasion were adverse predictors of survival. 相似文献
970.