全文获取类型
收费全文 | 591531篇 |
免费 | 302882篇 |
国内免费 | 58883篇 |
专业分类
耳鼻咽喉 | 5325篇 |
儿科学 | 7851篇 |
妇产科学 | 6139篇 |
基础医学 | 129483篇 |
口腔科学 | 8304篇 |
临床医学 | 108026篇 |
内科学 | 142589篇 |
皮肤病学 | 8677篇 |
神经病学 | 38509篇 |
特种医学 | 21347篇 |
外国民族医学 | 228篇 |
外科学 | 73750篇 |
综合类 | 110880篇 |
现状与发展 | 95篇 |
一般理论 | 39篇 |
预防医学 | 63563篇 |
眼科学 | 25670篇 |
药学 | 93600篇 |
430篇 | |
中国医学 | 65249篇 |
肿瘤学 | 43542篇 |
出版年
2023年 | 7539篇 |
2022年 | 17273篇 |
2021年 | 21229篇 |
2020年 | 19240篇 |
2019年 | 24040篇 |
2018年 | 24997篇 |
2017年 | 24678篇 |
2016年 | 22775篇 |
2015年 | 28013篇 |
2014年 | 31522篇 |
2013年 | 29713篇 |
2012年 | 38609篇 |
2011年 | 43044篇 |
2010年 | 34598篇 |
2009年 | 38576篇 |
2008年 | 30563篇 |
2007年 | 27299篇 |
2006年 | 26843篇 |
2005年 | 26510篇 |
2004年 | 21081篇 |
2003年 | 19247篇 |
2002年 | 17904篇 |
2001年 | 18601篇 |
2000年 | 14725篇 |
1999年 | 20410篇 |
1998年 | 18936篇 |
1997年 | 18797篇 |
1996年 | 18570篇 |
1995年 | 18658篇 |
1994年 | 17812篇 |
1993年 | 15431篇 |
1992年 | 15132篇 |
1991年 | 14024篇 |
1990年 | 12779篇 |
1989年 | 12303篇 |
1988年 | 11656篇 |
1987年 | 10918篇 |
1986年 | 10194篇 |
1985年 | 9119篇 |
1984年 | 6906篇 |
1983年 | 6786篇 |
1982年 | 7723篇 |
1981年 | 7220篇 |
1980年 | 6869篇 |
1979年 | 6719篇 |
1978年 | 5822篇 |
1977年 | 6126篇 |
1976年 | 5746篇 |
1975年 | 5485篇 |
1974年 | 5041篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
D. Caroline Blanchard Jon K. Shepherd Antonio De Padua Carobrez Robert J. Blanchard 《Neuroscience and biobehavioral reviews》1991,15(4):461-468
Female rats consistently show a pattern of differences in defensive behaviors compared to males which parallel the effects of exposure to a nonpainful threat stimulus (cat or cat odor) in the same tests and measures. These indications of greater defensiveness for females are particularly common in situations involving potential, as opposed to actual and present, threat, a factor which probably also reflects ceiling or floor effects in situations involving very intense defensiveness. In addition, pharmacological studies indicate sex differences in the effects of selective serotonin (5-HT) receptor agonists and antagonists on defensive responding. These findings indicate that sex effects must be considered in studies of the pharmacological control of defensive behaviors, and suggest that responsivity to sex effects may be an additional criterion for the suitability of animal models of anxiety. 相似文献
82.
Theoretical calculation of relative binding affinity in host-guest systems. 总被引:5,自引:3,他引:2 下载免费PDF全文
T P Lybrand J A McCammon G Wipff 《Proceedings of the National Academy of Sciences of the United States of America》1986,83(4):833-835
The relative free energy of binding the anions Cl- and Br- to the macrotricyclic receptor SC24 in water has been computed by a computer simulation technique. This result and an incidental result for the relative free energy of hydration of the anions are in excellent agreement with experimental data. The simulation approach to ligand-receptor interactions that is described here has significant potential as a predictive tool in chemistry, biochemistry, and pharmacology. 相似文献
83.
Xiaoguang Chen Yi Li Lei Wang Mark Katakowski Lijie Zhang Jieli Chen Yongxian Xu Subhash C. Gautam Michael Chopp 《Neuropathology》2002,22(4):275-279
Intravenous administration of human bone marrow stromal cells (hMSCs) after middle cerebral artery occlusion (MCAo) in rats provides functional benefit. We tested the hypothesis that these functional benefits are derived in part from hMSC production of growth and trophic factors. Quantitative sandwich enzyme‐linked immunosorbent assay (ELISA) of hMSCs cultured with normal and MCAo brain extracts were performed. hMSCs cultured in supernatant derived from ischemic brain extracts increased production of brain‐derived neurotrophic factor (BDNF), nerve growth factor (NGF), vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF). These neurotrophins and angiogenic growth factors increased in a post‐ischemia time‐dependent manner. The hMSC capacity to increase expression of growth and trophic factors may be the key to the benefit provided by transplanted hMSCs in the ischemic brain. 相似文献
84.
85.
86.
Performance characteristics of pooled rabbit IgG polyclonal anti-C3d are compared with one mouse IgM and three mouse IgG monoclonal anti-C3d antibodies (MAs). IgG MA,s employed singly or in combination, failed to precipitate C3d; by contrast, IgM MA and polyclonal anti-C3d precipitated C3d. Measurements of polyclonal anti-C3d concentration by chemical means and by 125I-C3d radioimmunoassay (RIA) agreed closely. RIA values were 50% of chemical measurement values for three of the four MAs. Use of sucrose density gradient ultracentrifugation to assess MA C3d/anti-C3d molar combining ratios for soluble anti-C3d/C3d was not possible because fast-sedimenting multimeric C3d/anti-C3d complexes did not form. Dissociation and competitive binding studies indicate that (1) two MAs had substantially lower affinities than the other anti-C3d antibodies, and (2) polyclonal anti-C3d recognizes more C3d epitopes than are recognized by individual MAs. The results demonstrate antigenic complexity of C3d fragment and illustrate the difficulties of predicting individual MA performance based on prior experience with polyclonal antibodies. 相似文献
87.
OBJECTIVE: To investigate the characteristics of the early stage treponema pallidum infected tissue in ear, nose, oropharynx and larynx and to raise relevance ratio of syphilis in nose and oropharynx and enhance doctor's self-protection awareness. METHODS: The histopathologic characteristics were studied by using HE staining, Warthin-Starry (W-S) staining was adopted to examine the treponema pallidum(TP) in lesion issue and its exudates smear for 12 cases biopsy tissues of suspicious syphilis. The diagnosis was confirmed by venereal disease research laboratory (VDRL), rapid plasma reagin circle test(RPR), treponema pallidum hemagglutination test(TPHA) and fluorescent treponemal antibody-absorption test (FTA-ABS). Treat with curing syphilis methods which published by nation. RESULTS: In the 12 cases mucous membrane specimen, the squamous epithelium proliferated, neutrophilic granulocyte infiltrated, within inherent membrane generous plasmacyte and lymphocyte infiltrated. W-S staining: plenty of treponema pallidum were found inside mucous membrane epithelium and exudate smear. Serology examination: 11 cases VDRL(++++), 7 cases RPR (+), 11 cases TPHA(+), 1 case FTA-ABS(+). After systemic treatment, 11 cases are clinically recovered. All patients serology become negative. CONCLUSION: W-S staining method can directly demonstrate histopathologic characteristics in early syphilis, in intrinsic membrane numerous plasmacyte infiltration. Combining with specific syphilis serology examination could increase diagnosis rate of syphilis in nose and oropharynx. 相似文献
88.
Torsten T. Bauer Joachim Lorenz Klaus-Friedrich Bodmann Friedrich Vogel 《Medizinische Klinik》2005,26(13):355-360
Hintergrund:
Die nosokomiale Pneumonie gehört zu den häufigsten nosokomialen Infektionen und ist die häufigste auf der Intensivstation. Die nosokomiale Pneumonie ist mit einer signifikanten Mortalität und Morbidität assoziiert, und ihr Auftreten verschlechtert die Prognose des Patienten deutlich. Nach der Definition der DRGs auch im deutschen Krankenhaussystem ist die nosokomiale Pneumonie überwiegend Sache des Krankenhauses und kann somit nicht nur das Ergebnis der Patientenbehandlung, sondern auch das finanzielle Ergebnis des Krankenhauses beeinträchtigen. 相似文献89.
90.