全文获取类型
收费全文 | 6454篇 |
免费 | 665篇 |
国内免费 | 69篇 |
专业分类
耳鼻咽喉 | 66篇 |
儿科学 | 296篇 |
妇产科学 | 78篇 |
基础医学 | 776篇 |
口腔科学 | 124篇 |
临床医学 | 649篇 |
内科学 | 1206篇 |
皮肤病学 | 368篇 |
神经病学 | 457篇 |
特种医学 | 355篇 |
外科学 | 952篇 |
综合类 | 184篇 |
一般理论 | 8篇 |
预防医学 | 516篇 |
眼科学 | 41篇 |
药学 | 466篇 |
中国医学 | 3篇 |
肿瘤学 | 643篇 |
出版年
2021年 | 71篇 |
2019年 | 73篇 |
2018年 | 79篇 |
2017年 | 55篇 |
2016年 | 76篇 |
2015年 | 77篇 |
2014年 | 96篇 |
2013年 | 147篇 |
2012年 | 197篇 |
2011年 | 195篇 |
2010年 | 155篇 |
2009年 | 145篇 |
2008年 | 230篇 |
2007年 | 282篇 |
2006年 | 255篇 |
2005年 | 241篇 |
2004年 | 225篇 |
2003年 | 236篇 |
2002年 | 186篇 |
2001年 | 198篇 |
2000年 | 223篇 |
1999年 | 206篇 |
1998年 | 91篇 |
1997年 | 103篇 |
1996年 | 102篇 |
1995年 | 98篇 |
1994年 | 76篇 |
1993年 | 68篇 |
1992年 | 153篇 |
1991年 | 189篇 |
1990年 | 174篇 |
1989年 | 150篇 |
1988年 | 193篇 |
1987年 | 168篇 |
1986年 | 138篇 |
1985年 | 182篇 |
1984年 | 111篇 |
1983年 | 118篇 |
1982年 | 72篇 |
1981年 | 67篇 |
1980年 | 59篇 |
1979年 | 109篇 |
1978年 | 103篇 |
1977年 | 78篇 |
1976年 | 76篇 |
1975年 | 74篇 |
1974年 | 93篇 |
1973年 | 101篇 |
1972年 | 73篇 |
1971年 | 73篇 |
排序方式: 共有7188条查询结果,搜索用时 15 毫秒
41.
42.
43.
44.
Studies requiring identification of consonant-vowel-consonant (CVC) nonwords have suggested that attention is distributed more slowly or sequentially across the letters when they are presented to the right hemisphere than to the left hemisphere. Two experiments investigated whether hemispheric differences in processing strategy would be reduced with reductions of hemispheric differences in accuracy. The magnitude of visual field differences in accuracy was controlled by manipulating exposure duration, and the effect was observed on visual field differences in processing strategy. For both CVC identification (Experiment 1) and identification of nonletter symbols (Experiment 2), hemispheric strategy differences were independent of differences in accuracy. Both quantitative and qualitative hemispheric differences in processing visual displays appear to depend on the nature of the stimuli and the nature of the processes they invoke. 相似文献
45.
The definition of the temporal sequence of appearance of fetal markers during prenatal and early postnatal development in Sertoli and germ cells may be important for understanding the mechanisms underlying their reexpression in disorders of the adult testis. For this reason, we studied the expression of Sertoli and germ cell markers in 25 human testes spanning a period from 8 gestational weeks to 4 years. Well-characterized antibodies were employed to anti-Müllerian hormone (AMH), cytokeratin 18 (CK18), vimentin (VIM), M2A-antigen (M2A), germ cell alkaline phosphatase (GCAP), and somatic angiotensin-converting enzyme (sACE) on formalin-fixed and microwave-pretreated paraffin sections. In Sertoli cells, AMH and VIM were consistently present. While VIM and CK18 were coexpressed in embryonic testes, CK18 was progressively downregulated and completely absent from the 20th gestational week. M2A was absent or moderately expressed in fetal Sertoli cells but increased during further development. In germ cells, M2A was consistently found in primordial germ cells (PGCs) as well as in M- and T1-prespermatogonia. In contrast, sACE and GCAP were absent from PGCs but were a distinct feature of late M- and early T1-prespermatogonia and appeared predominantly between the 18th and the 22nd gestational weeks. Both T2-prespermatogonia and postnatal prespermatogonia were devoid of any marker. While CK18 represents a differentiation marker for fetal Sertoli cells, M2A, GCAP, and sACE can be used as differentiation markers for the discrimination of different germ cell types during human prespermatogenesis. Because various immunophenotypes reflect distinct differentiation stages, this knowledge may be important for understanding adult testicular pathology. 相似文献
46.
47.
Three monoclonal antibodies (MAb), 21 (IgG1), I10 (IgG1) and H38 (IgG2b), to insulin have been tested for cross-reactivity with 11 species variants of insulin and three of proinsulin. Correlations of differences of reactivities between the MAb and the species variants of insulin with the respective amino acid sequences of the latter have permitted the identification of two epitopes recognized by the MAb which encompass the regions in the A- and B-chains of insulin subject to frequent evolutionary amino acid substitutions. MAb 21 and H38 are directed to an epitope which includes residues B27-30 and A1 or A4 and can discriminate between human and pig insulins which differ only at B30. MAb 21 reacts with human (B30 thr) but not with pig (B30 ala) insulins, whereas MAb H38 exhibits a reciprocal specificity. Neither MAb 21 nor MAb H38 react with human or pig proinsulins respectively indicating that the presence of the C-peptide joining A1 to B30 masks the epitope. MAb 21 reacts with human insulin 125I-labeled at tyr A14 but not B26 suggesting that incorporation of the I atom at B26 also masks the epitope. MAb I10 is directed to an epitope which includes A8-10 and A4 or B3 with a specificity for the human A8-10 sequence. MAb I10 reacts with human proinsulin and human insulin 125I-labeled at either tyr A14 or B26. 相似文献
48.
Cholinergic, serotoninergic and neuropeptidergic components of the nervous system were examined and compared in the progenetic metacercaria and adult gasterostome trematode, Bucephaloides gracilescens in order to provide baseline information on neuronal control of the musculature involved in egg-assembly. Enzyme cytochemistry and indirect immunocytochemical techniques interfaced with confocal scanning laser microscopy demonstrated all three classes of neuroactive substance throughout the central and peripheral nervous systems. A comparable orthogonal arrangement of the central nervous system (CNS) and peripheral array of nerve plexuses was observed in both metacercaria and adult. Staining patterns for cholinergic and peptidergic substances showed significant overlap, while the serotoninergic system was confined to a separate set of neurons. Immunostaining for FMRFamide-related peptides (FaRPs) was strong in the CNS and peripheral innervation to the attachment apparatus of metacercaria and adult but was only found in the innervation of the ootype in ovigerous adults, implicating FaRPs in neuronal control of the muscle of the female reproductive tract during egg-assembly. 相似文献
49.
50.
Role of antibody to S100 protein in diagnostic pathology 总被引:1,自引:0,他引:1