全文获取类型
收费全文 | 5906篇 |
免费 | 426篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 101篇 |
儿科学 | 93篇 |
妇产科学 | 78篇 |
基础医学 | 996篇 |
口腔科学 | 90篇 |
临床医学 | 594篇 |
内科学 | 1260篇 |
皮肤病学 | 166篇 |
神经病学 | 524篇 |
特种医学 | 316篇 |
外科学 | 679篇 |
综合类 | 33篇 |
一般理论 | 2篇 |
预防医学 | 388篇 |
眼科学 | 117篇 |
药学 | 425篇 |
中国医学 | 9篇 |
肿瘤学 | 481篇 |
出版年
2023年 | 26篇 |
2022年 | 87篇 |
2021年 | 148篇 |
2020年 | 67篇 |
2019年 | 118篇 |
2018年 | 139篇 |
2017年 | 119篇 |
2016年 | 154篇 |
2015年 | 195篇 |
2014年 | 208篇 |
2013年 | 267篇 |
2012年 | 377篇 |
2011年 | 448篇 |
2010年 | 245篇 |
2009年 | 292篇 |
2008年 | 421篇 |
2007年 | 387篇 |
2006年 | 424篇 |
2005年 | 397篇 |
2004年 | 413篇 |
2003年 | 363篇 |
2002年 | 309篇 |
2001年 | 75篇 |
2000年 | 55篇 |
1999年 | 51篇 |
1998年 | 73篇 |
1997年 | 65篇 |
1996年 | 35篇 |
1995年 | 33篇 |
1994年 | 29篇 |
1993年 | 23篇 |
1992年 | 19篇 |
1991年 | 19篇 |
1990年 | 21篇 |
1989年 | 15篇 |
1988年 | 8篇 |
1987年 | 10篇 |
1986年 | 20篇 |
1985年 | 7篇 |
1982年 | 15篇 |
1981年 | 9篇 |
1980年 | 7篇 |
1979年 | 12篇 |
1978年 | 16篇 |
1977年 | 8篇 |
1975年 | 10篇 |
1974年 | 12篇 |
1973年 | 10篇 |
1972年 | 7篇 |
1971年 | 6篇 |
排序方式: 共有6352条查询结果,搜索用时 15 毫秒
11.
12.
Christian Foged Christer Halldin Christian Loc’h Bernard Mazière Stefan Pauli Mariannick Maziére Holger C. Hansen Tetsuya Suhara Carl-Gunnar Swahn Per Karlsson Lars Farde 《European journal of nuclear medicine and molecular imaging》1997,24(10):1261-1267
NNC 13-8241 has recently been labelled with iodine-123 and developed as a metabolically stable benzodiazepine receptor ligand
for single-photon emission computed tomography (SPECT) in monkeys and man. NNC 13-8199 is a bromo-analogue of NNC 13-8241.
This partial agonist binds selectively and with subnanomolar affinity to the benzodiazepine receptors. We prepared 76Br labelled NNC 13-8199 from the trimethyltin precursor by the chloramine-T method. Carbon-11 labelled NNC 13-8199 was synthesised
by N-alkylation of the nitrogen of the amide group with [11C]methyl iodide. Positron emission tomography (PET) examination with the two radioligands in monkeys demonstrated a high uptake
of radioactivity in the occipital, temporal and frontal cortex. In the study with [76Br]NNC 13-8199, the monkey brain uptake continued to increase until the time of displacement with flumazenil at 215 min after
injection. For both radioligands the radioactivity in the cortical brain regions was markedly reduced after displacement with
flumazenil. More than 98% of the radioactivity in monkey plasma represented unchanged radioligand 40 min after injection.
The low degree of metabolism indicates that NNC 13-8199 is metabolically much more stable than hitherto developed PET radioligands
for imaging of benzodiazepine receptors in the primate brain. [76Br]NNC 13-8199 has potential as a radioligand in human PET studies using models where a slow metabolism is an advantage.
Received 19 April and in revised form 10 June 1997 相似文献
13.
14.
15.
16.
Michael Krause Agns Rouleau Holger Stark Peter Luger Monique Garbarg Jean-Charles Schwartz Walter Schunack 《Archiv der Pharmazie》1996,329(4):209-215
The therapeutic value of histamine H3-receptor ligands is under current investigation. On the basis of recently described diaryl imine prodrugs of the histamine H3-receptor agonist (R)-α-methyl-histamine ( 1 ) a series of new azomethine prodrugs containing five- and six-membered heterocycles were synthesized and tested for their in vitro hydrolysis rates and in vitro activity after oral application. It was found that electron-deficient six-membered heterocycles drastically destabilized the imine double bond so that these prodrugs decomposed unsuitably fast. On the contrary, prodrugs containing five-membered heterocycles appeared to be highly effective for the CNS delivery of 1 , and a remarkable correlation between chemical structure and pharmacokinetic profile was observed. Particularly (R)-4-fluoro-2-[[N-[1-(1H-imidazol-4-yl)-2-propyl]imino](1H-pyrrol-2-yl)methyl]phenol ( 8c ), the 2-furanyl analogue 8d , and its 3-furanyl isomer 8e proved to be equipotent to the most potent of recently described halogenated diaryl imine prodrugs of 1. However, in contrast to any other azomethine prodrug, 8c exhibited an incomparably long lasting delivery of 1 in the CNS and can thus be regarded as a ‘retard’ prodrug. Assuming that a therapeutic indication of histamine H3-receptor agonists will soon be established, these highly potent heteroarylphenyl azomethine prodrugs, which already serve as valuable pharmacological tools, may also become potential drugs in clinical use. 相似文献
17.
Automated extraction of genomic DNA from medically important yeast species and filamentous fungi by using the MagNA Pure LC system 总被引:5,自引:0,他引:5 下载免费PDF全文
Loeffler J Schmidt K Hebart H Schumacher U Einsele H 《Journal of clinical microbiology》2002,40(6):2240-2243
A fully automated assay was established for the extraction of DNA from clinically important fungi by using the MagNA Pure LC instrument. The test was evaluated by DNA isolation from 23 species of yeast and filamentous fungi and by extractions (n = 28) of serially diluted Aspergillus fumigatus conidia (10(5) to 0 CFU/ml). Additionally, DNA from 67 clinical specimens was extracted and compared to the manual protocol. The detection limit of the MagNA Pure LC assay of 10 CFU corresponded to the sensitivity when DNA was extracted manually; in 9 of 28 runs, we could achieve a higher sensitivity of 1 CFU/ml blood, which was found to be significant (p 相似文献
18.
Physical Deletion of the p53 Gene in Bladder Cancer: Detection by Fluorescence in Situ Hybridization 总被引:1,自引:6,他引:1 下载免费PDF全文
Guido Sauter Guoren Deng Holger Moch Russell Kerschmann Kouji Matsumura Sandy De Vries Tracy George Jose Fuentes Peter Carroll Michael J. Mihatsch Frederic M. Waldman 《The American journal of pathology》1994,144(4):756-766
To understand better the role of physical p53 deletion in bladder cancer, 106 formalin-fixed and 45 unfixed bladder tumors were examined using fluorescence in situ hybridization. Probes for centromere 17 and the p53 locus were hybridized simultaneously to interphase tumor cells to analyze p53 and chromosome 17 copy number on a cell by cell basis. 17p deletion was found in four of 43 pTa tumors, 18 of 43 pT1 tumors and 29 of 58 pT2-4 tumors (P = 0.0001). 17p deletion was also highly correlated with grade (P = 0.0001) and with p53 immunostaining (P = 0.0005). Chromosome 17 polysomy was associated with stage, grade, 17p deletions, and p53 immunostaining (P = 0.0001). The strong difference in centromere 17 copy number and 17p deletions between pTa and pT1 tumors supports a relevant biological distinction between pTa and pT1 tumors. 相似文献
19.
In sera from 12 patients with polar tuberculoid leprosy, 12 with subpolar tuberculoid leprosy, and 16 with lepromatous leprosy were demonstrated a total number of 125 anti-BCG precipitins by means of crossed immunoelectrophoresis with intermediate gel. Up to 14 different precipitins were found in individual sera, and the complexity in antibody response was higher than previously realized. The specificity of 69% of the antibodies was defined, and these antibodies were titrated in three arbitrary titer units. A highly significant difference (P < 0.002) was found in antibody response between the tuberculoid and the lepromatous group. Due to simplicity, sensitivity, and high resolution, the method used is a promising tool for providing exact data to be used as guidelines for purification of important individual mycobacterial antigens. The need for reference antisera is emphasized. 相似文献
20.
Holger Arndt Paul Kubes Matthew B. Grisham Enrique Gonzalez D. Neil Granger 《Inflammation》1992,16(5):549-559
The objective of this study was to determine the turnover rate of the extravascular pool of granulocytes in different regions of the feline gastrointestinal tract. Leukocyte emigration from the vasculature was prevented over a 48-h period by repeated intravenous injections of a monoclonal antibody (MAb IB4) directed against the leukocyte adhesion glycoprotein complex CD11/CD18. Tissue-associated myeloperoxidase (MPO) activity was used to monitor the total tissue granulocyte pool at 0.5, 12, 24, and 48 h after MAb IB4 administration. The mucosal layer of the duodenum, jejunum, ileum, and colon exhibited different kinetics of granulocyte clearance, with average life-spans (t1/2) ranging between 6.9 (colon) and 10.4 h (duodenum). Granulocyte clearance rates of 0.5 × 106 and 2.4 x 106 cells/h/g tissue were estimated (from measured values oft1/2 and tissue granulocyte pool) for the small bowel and colonie mucosae, respectively. The submucosal layer of the intestine exhibited a biphasic reduction in tissue MPO activity following immunoneutralization of CD11/CD18, with an initialt1/2 0.5 h followed by at1/2 of 36–60 h. The initial rapid decline in tissue MPO suggests that a significant fraction of granulocytes in the submucosa is localized in a readily exchangeable pool (e.g., marginated cells within the vasculature). The results of this study indicate that the average life-span of resident granulocytes varies significantly between different regions of the gastrointestinal tract, with the intestinal mucosa exhibiting at1/2 comparable to that previously reported for circulating feline neutrophils (R 8 h). 相似文献