全文获取类型
收费全文 | 15543篇 |
免费 | 725篇 |
国内免费 | 105篇 |
专业分类
耳鼻咽喉 | 121篇 |
儿科学 | 243篇 |
妇产科学 | 266篇 |
基础医学 | 1792篇 |
口腔科学 | 293篇 |
临床医学 | 1003篇 |
内科学 | 3978篇 |
皮肤病学 | 284篇 |
神经病学 | 818篇 |
特种医学 | 643篇 |
外科学 | 3357篇 |
综合类 | 74篇 |
一般理论 | 1篇 |
预防医学 | 483篇 |
眼科学 | 289篇 |
药学 | 780篇 |
中国医学 | 30篇 |
肿瘤学 | 1918篇 |
出版年
2023年 | 114篇 |
2022年 | 212篇 |
2021年 | 323篇 |
2020年 | 185篇 |
2019年 | 226篇 |
2018年 | 325篇 |
2017年 | 263篇 |
2016年 | 285篇 |
2015年 | 333篇 |
2014年 | 415篇 |
2013年 | 481篇 |
2012年 | 835篇 |
2011年 | 956篇 |
2010年 | 558篇 |
2009年 | 461篇 |
2008年 | 885篇 |
2007年 | 950篇 |
2006年 | 856篇 |
2005年 | 860篇 |
2004年 | 811篇 |
2003年 | 789篇 |
2002年 | 718篇 |
2001年 | 406篇 |
2000年 | 396篇 |
1999年 | 383篇 |
1998年 | 224篇 |
1997年 | 152篇 |
1996年 | 153篇 |
1995年 | 111篇 |
1994年 | 97篇 |
1993年 | 109篇 |
1992年 | 238篇 |
1991年 | 193篇 |
1990年 | 186篇 |
1989年 | 185篇 |
1988年 | 174篇 |
1987年 | 173篇 |
1986年 | 149篇 |
1985年 | 157篇 |
1984年 | 116篇 |
1983年 | 101篇 |
1982年 | 55篇 |
1979年 | 78篇 |
1978年 | 68篇 |
1977年 | 53篇 |
1975年 | 44篇 |
1974年 | 48篇 |
1973年 | 48篇 |
1971年 | 50篇 |
1968年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
IL-1 is required for allergen-specific Th2 cell activation and the development of airway hypersensitivity response 总被引:1,自引:0,他引:1
Nakae S Komiyama Y Yokoyama H Nambu A Umeda M Iwase M Homma I Sudo K Horai R Asano M Iwakura Y 《International immunology》2003,15(4):483-490
IL-1 is a pro-inflammatory cytokine consisted of two molecular species, IL-1alpha and IL-1beta, and the IL-1 receptor antagonist (IL-1Ra) is a natural inhibitor of both molecules. Although it is suggested that IL-1 potentiates immune responses mediated by T(h)2 cells, the role of IL-1 in asthma still remains unclear. In this study, we demonstrate that the ovalbumin (OVA)-induced airway hypersensitivity response (AHR) in IL-1alpha/beta-deficient (IL-1alpha/beta(-/-)) mice was significantly reduced from the levels seen in wild-type mice, whereas the responses seen in IL-1Ra(-/-) mice were profoundly exacerbated, suggesting that IL-1 is required for T(h)2 cell activation during AHR. OVA-specific T cell proliferation, IL-4 and IL-5 production by T cells, and IgG1 and IgE production by B cells in IL-1alpha/beta(-/-) mice were markedly reduced compared with these responses in wild-type mice; such responses were enhanced in IL-1Ra(-/-) mice. Using IL-1alpha(-/-) and IL-1beta(-/-) mice, we determined that both IL-1alpha and IL-1beta are involved in this reaction. Both IgG1 and IgE levels were reduced in IL-1beta(-/-) mice, while only IgE levels were affected in IL-1alpha(-/-) mice, indicating a functional difference between IL-1alpha and IL-1beta. These observations indicate that IL-1 plays important roles in the development of AHR. 相似文献
83.
84.
Diverse functions of the p75 neurotrophin receptor 总被引:5,自引:0,他引:5
Yamashita T Fujitani M Hata K Mimura F Yamagishi S 《Anatomical science international / Japanese Association of Anatomists》2005,80(1):37-41
The pan-neurotrophin receptor p75NTR belongs to a large family of receptors, which includes tumor necrosis factor receptors, Fas and approximately 25 other members. The p75NTR is the first receptor to be cloned molecularly. Recent years have seen the emergence of a consensus regarding the signaling pathways activated by p75NTR and its potential biological function, although receptor characterization had not been targeted for some years. We now know that p75NTR has surprisingly diverse effects, ranging from cell death to regulation of axon elongation. This diversity can be explained by the complex formation of p75NTR with other receptors and multiple signaling molecules that interact with the intracellular domain of p75NTR. 相似文献
85.
86.
Kenji Kashima Shigeo Yokoyama Tsutomu Daa Iwao Nakayama Torn Iwaki 《Virchows Archiv : an international journal of pathology》1997,430(4):333-338
The influence of free radicals on apoptosis was studied in the human heart; 45 autopsy cases were examined by the nick end labelling method (NELM) that detects DNA fragmentation. Immunostaining for copper-zinc superoxide dismutase (CuZn-SOD) and tissue transglutaminase (tTG) induced frequently during apoptosis were also studied. Positive immunoreaction for tTG was detected in mucinous degeneration of myocardial cells; these same cells were also positive for CuZn-SOD but negative for NELM. Myocardial cells showing basophilic alterations after haematoxylin and eosin staining were also positive for CuZn-SOD but negative for the other markers examined. Positive nuclear reaction by NELM was only observed in myocardial cells showing contraction band necrosis or irregularly shaped nuclei surrounding recent or long-standing infarcted foci. In these the other two markers were negative. Since mucinous degeneration lacks the distinguishing morphological features of apoptosis, immunoreactive tTG in this lesion may not imply that the cells are undergoing apoptosis. tTG can be induced in non-apoptotic conditions and may not be involved in apoptosis induced by infarction. Histological disassociation between CuZn-SOD expression and apoptosis suggests the possibility of a cytoprotective role played by endogenous CuZn-SOD against free radical generation in the human heart. 相似文献
87.
I Nakayama S Noguchi Y Mochizuki N Murakami H Yamashita A Moriuchi S Yokoyama A Noguchi 《Acta pathologica japonica》1984,34(1):19-28
Five cases of adenomatous goiter have been studied by an electron microscope using an immuno-reaction for thyroglobulin (TG) and focusing on the mechanism of endocytosis. Positive stain for TG was demonstrated in follicular lumina, large reabsorbed colloid droplets and small subapical vesicles. Endocytotic vesicles ranging from 320 nm to 1600 nm in diameter were observed in the cytoplasm as pits in the apical plasma membrane. Some of them showed direct connection with the positive stain for TG in the follicular lumen and the others were completely ingested in the cytoplasm. With statistic analysis, a majority of the vesicles showing the positive stain for TG in the cytoplasm distributed in the range of 200 nm to 1200 nm in diameter with the peak in 300 nm to 399 nm and was situated within an extent of the diameter measured from the endocytotic vesicles. Engulfment of colloid by pseudopods and fusion of the reabsorbed colloid droplets were encountered as extremely rare findings and appeared to play no major role for formation of large colloid droplets in adenomatous goiter. 相似文献
88.
89.
Seiiohi Sumino Kazuo Nacsashima Tetsuro Shimamine Toshiaki Abe Hideo Tsuneyoshi Satoru Murao 《Pathology international》1983,33(3):629-643
Autopsy findings in a 40-year-old male with heredofamilial amyloidosis and polyneuropathy are reported. He had been suffering from progressive autonomic as well as sensorimotor dysfunctions. Prominent amyloid deposit was found in the kidney, heart, thyroid, and testis, and less in the interstitium and small vessels of almost all organs. The peripheral nerves, some showing prominent hypertrophy, were most severely involved by amyloid deposit in a form of stellate mass, which ultrastructurally consisted of radially arranged amyloid filaments. In the hypertrophied nerves and ganglia, in addition to amyloid, massive accumulation of acid mucopolysaccharide (AMPS) was seen filling up the interstitial space, which was the cause of hypertrophy. Ultrastructurally, AMPS was seen as finely granular substance. An extracted amyloid from the kidney showed 8 nm filament on negative staining and was estimated of having a molecular weight of 14,000. 相似文献
90.
Yokoyama Y; Takahashi Y; Morishita S; Hashimoto M; Niwa K; Tamaya T 《Molecular human reproduction》1998,4(2):173-177
In a total of 41 endometrial tissue samples, the relationship between
telomerase activity and proliferating cell nuclear antigen (PCNA) labelling
index was studied. In samples of endometrium from the proliferative phase
of the menstrual cycle, telomerase activity was found in 15 out of 17 cases
(88%). Two samples from the early proliferative phase showed negative
telomerase activity and a low PCNA labelling index. However, three out of
16 samples of early secretory phase endometrium showed telomerase activity
and a PCNA labelling index. In mid- to late secretory phase endometrium, in
menopausal endometrium and in decidualized endometrium induced by
progesterone neither telomerase activity nor PCNA labelling was found.
These results suggest that telomerase activity of the endometrium may be
correlated with the proliferative potential of the epithelial cells and
that its activity may be regulated by oestrogen.
相似文献