全文获取类型
收费全文 | 7989篇 |
免费 | 759篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 70篇 |
儿科学 | 206篇 |
妇产科学 | 225篇 |
基础医学 | 1100篇 |
口腔科学 | 270篇 |
临床医学 | 765篇 |
内科学 | 1796篇 |
皮肤病学 | 279篇 |
神经病学 | 707篇 |
特种医学 | 309篇 |
外科学 | 982篇 |
综合类 | 61篇 |
一般理论 | 5篇 |
预防医学 | 608篇 |
眼科学 | 136篇 |
药学 | 344篇 |
中国医学 | 3篇 |
肿瘤学 | 896篇 |
出版年
2023年 | 40篇 |
2022年 | 62篇 |
2021年 | 184篇 |
2020年 | 109篇 |
2019年 | 173篇 |
2018年 | 135篇 |
2017年 | 145篇 |
2016年 | 153篇 |
2015年 | 181篇 |
2014年 | 233篇 |
2013年 | 284篇 |
2012年 | 461篇 |
2011年 | 481篇 |
2010年 | 290篇 |
2009年 | 247篇 |
2008年 | 384篇 |
2007年 | 443篇 |
2006年 | 440篇 |
2005年 | 443篇 |
2004年 | 424篇 |
2003年 | 379篇 |
2002年 | 355篇 |
2001年 | 228篇 |
2000年 | 222篇 |
1999年 | 177篇 |
1998年 | 109篇 |
1997年 | 95篇 |
1996年 | 66篇 |
1995年 | 45篇 |
1994年 | 70篇 |
1993年 | 66篇 |
1992年 | 122篇 |
1991年 | 119篇 |
1990年 | 103篇 |
1989年 | 117篇 |
1988年 | 115篇 |
1987年 | 98篇 |
1986年 | 111篇 |
1985年 | 83篇 |
1984年 | 79篇 |
1983年 | 69篇 |
1982年 | 62篇 |
1981年 | 38篇 |
1980年 | 36篇 |
1979年 | 49篇 |
1978年 | 51篇 |
1977年 | 29篇 |
1976年 | 34篇 |
1975年 | 39篇 |
1974年 | 37篇 |
排序方式: 共有8762条查询结果,搜索用时 156 毫秒
101.
Nanda Navreet K.; Sercarz Eli E.; Hsu Di-Hwel; Kronenberg Mitchell 《International immunology》1994,6(5):731-737
We report that the lymphokines (IFN-) and IL-10 are co-syntheslzedby previously described CD3+ TCRß+, minor antigen-specificsuppressor T cell clones. IFN- and IL-10 are known to (I) becharacteristically produced by different helper T cell types,Th1 and Th2 respectively, and (II) inhibit the function of thereciprocal subset of T cells: IFN- Inhibits the function ofTh2 and IL-10 that of Th1 cells. Although Th0 cells are alsoknown to synthesize cytoklnes of both the Th1- and Th2-typeT cells, the suppressor T cells described in this report aredifferent from Th0 cells in that they produce (I) neither IL-2nor IL-4 molecules and (II) stimulation via their CD3-TCR systemseems independent of both IL-2 and IL-4, the typical autocrinemolecules for T cell proliferation. The lymphokine profile ofthese suppressor T (TJ cell clones, as well as those of humanantigen-specific T. cells reported earlier, suggests that co-synthesisof some Th1-llke and some Th2-like cytoklnes may be a characteristicof antigen-specific T, cells as opposed to the type of reciprocalinhibition mediated through IFN- or IL-10, which is antigennon-specific. 相似文献
102.
Expression of T cell receptor delta chains in benign and malignant T lineage lymphoproliferations 总被引:4,自引:3,他引:4
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Recent studies in both human and murine systems have demonstrated the existence of a second CD3-associated T cell receptor (the gamma delta-TCR) distinct from the alpha beta heterodimer associated with antigen recognition by classical T cells. Using a monoclonal antibody specific for the delta component of the human gamma delta-TCR, the expression of this antigen in both benign, reactive lymphoid tissues and T lineage lymphomas was studied with immunohistologic techniques. In the normal thymus, TCR-delta+ cells constituted less than 5% of the CD3+ thymocytes and were located primarily in the medulla or juxtamedullary cortex. Within the T zones of 16 histologically varied reactive peripheral lymphoid tissues, including four patients with marked predominantly paracortical hyperplasia, the authors identified from less than 1% to a maximum of 5% TCR-delta+ cells. While these results are consistent with the hypothesis that TCR-gamma delta+ cells comprise a small distinct subpopulation of peripheral T cells in humans, selective localization or recruitment of these cells could not be demonstrated in any of a number of tissues or reactive situations. Among 62 T lineage lymphomas, including 14 CD3+/TCR-beta- cases, only two TCR-delta+ neoplasms were identified, both lymphoblastic lymphomas displaying the CD3+/CD4-/CD8- phenotype known to be associated with normal TCR-gamma delta+ T cells. Because the majority of CD3+/TCR-beta- lymphomas did not display TCR-delta, these results argue against the hypothesis that the high incidence of CD3/TCR-beta discordance noted in T lineage lymphomas represents preferential transformation of the TCR-delta-expressing subset. 相似文献
103.
Brouwer AM Brenner E Smeets JB 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2002,143(2):198-211
We investigated what information subjects use when trying to hit moving targets. In particular, whether only visual information about the target's position is used to guide the hand to the place of interception or also information about its speed. Subjects hit targets that moved at different constant speeds and disappeared from view after varying amounts of time. This prevented the subjects from updating position information during the time that the target was invisible. Subjects hit further ahead of the disappearing point when the target moved faster, but not as much as they should have on the basis of the target's speed. This could be because more time is needed to perceive and use the correct speed than was available before the target disappeared. It could also be due to a speed-related misperception of the target's final position. The results of a second experiment were more consistent with the latter hypothesis. In a third experiment we moved the background to manipulate the perceived speed. This did not affect the hitting positions. We conclude that subjects respond only to the changing target position. Target speed influences the direction in which the hand moves indirectly, possibly via a speed-related misperception of position. 相似文献
104.
S100A2, a putative tumor suppressor gene, regulates in vitro squamous cell carcinoma migration 总被引:14,自引:0,他引:14
Nagy N Brenner C Markadieu N Chaboteaux C Camby I Schäfer BW Pochet R Heizmann CW Salmon I Kiss R Decaestecker C 《Laboratory investigation; a journal of technical methods and pathology》2001,81(4):599-612
It has been previously shown that S100A2 is down-regulated in tumor cells and can be considered a tumor suppressor. We have recently shown that this down-regulation can be observed particularly in epithelial tissue, where S100A2 expression decreases remarkably in tumors as compared with normal specimens. In the present paper we investigate whether S100A2 could play a tumor-suppressor role in certain epithelial tissues by acting at the cell migration level. To this end, we made use of five in vitro human head and neck squamous cell carcinoma lines in which we characterized S100A2 expression at both RNA and protein level. To characterize the influence of S100A2 on cell kinetic and cell motility features, we used two complementary approaches involving specific antisense oligonucleotides and the addition of S100A2 to the culture media. The different expression analyses gave a coherent demonstration of the fact that the FADU and the RPMI-2650 cell lines exhibit high and low levels of S100A2 expression, respectively. Antisense oligonucleotides (in FADU) and extracellular treatments (in RPMI) showed that, for these two models, S100A2 had a clear inhibitory influence on cell motility while modifying the cell kinetic parameters only slightly. These effects seem to be related, at least in part, to a modification in the polymerization/depolymerization dynamics of the actin microfilamentary cytoskeleton. Furthermore, we found evidence of the presence of the receptor for advanced glycation end-products (RAGE) in RPMI cells, which may act as a receptor for extracellular S100A2. The present study therefore presents experimentally based evidence showing that S100A2 could play a tumor-suppressor role in certain epithelial tissues by restraining cell migration features, at least in the case of head and neck squamous cell carcinomas. 相似文献
105.
Transport of molecules across renal glomerular capillaries 总被引:7,自引:0,他引:7
106.
Quantitative assessment of proximal tubule function in single nephrons of the rat kidney 总被引:7,自引:0,他引:7
B M Brenner T M Daugharty I F Ueki J L Troy 《The American journal of physiology》1971,220(6):2058-2067
107.
Pyogenic granuloma-like reaction in the necrotic, vessels-deprived femoral head of the rat 总被引:2,自引:0,他引:2
Bejar J Misselevich I Peled E Zinman C Reis DN Boss JH 《Experimental and molecular pathology》2005,78(2):140-143
Osteonecrosis of the femoral head was produced in rats by cutting the ligamentum teres and incising the cervical periosteum. As of the second postoperative week, fibrous tissue pervaded the necrotic epiphyses, macrophages and osteoclasts removed the debris, osteoblasts deposited lamellar-fibred and woven-fibred intramembranous bone, and remodeling began. In 16% of the rats killed during the 2nd postoperative week, the epiphyses contained big fragments of necrotic bone enclosed by densely packed, capillary-sized vessels. Ingrowth of this hypervascularized, pyogenic granuloma-like tissue is presumably due to the presence of excessive growth factors, reflecting an exaggerated pathophysiological reaction within the framework of organization of the necrotic epiphyses. 相似文献
108.
Micropuncture studies were performed in Munich-Wistar rats with surgically created chronic partial unilateral ureteral obstruction (UUO). Mean values for superficial single nephron (SN)GFR, total GFR, and initial glomerular plasma flow rate (QA) in obstructed kidneys were essentially identical to values in nonobstructed kidneys. Nevertheless, glomerular capillary hydraulic pressure (PGC) was significantly higher in obstructed than in nonobstructed kidneys. This increase in PGC served to offset the markedly reduced glomerular capillary ultrafiltration coefficient that was also confined to the kidneys ipsilateral to the ureteral obstruction. During infusion of indomethacin or meclofenamate, SNGFR and QA decreased significantly, in association with elevations in arteriolar resistances in obstructed kidneys, whereas such changes were not observed in nonobstructed kidneys. The results suggest that local intrarenal factors, rather than circulating or systemic factor(s), bring about functional adaptations to partial ureteral obstruction. In particular, an indomethacin- and meclofenamate-sensitive vasodilator (presumably prostaglandin) plays a role in antagonizing the effects of a simultaneously acting vasoconstrictor which, although not identified, displayed the functional properties of angiotensin II. 相似文献
109.
110.
Tumor necrosis factor alpha-induced interleukin-8 production via NF-kappaB and phosphatidylinositol 3-kinase/Akt pathways inhibits cell apoptosis in human hepatocytes 总被引:3,自引:0,他引:3
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Osawa Y Nagaki M Banno Y Brenner DA Asano T Nozawa Y Moriwaki H Nakashima S 《Infection and immunity》2002,70(11):6294-6301
Tumor necrosis factor alpha (TNF-alpha) not only induces apoptotic signals but also causes antiapoptotic and regenerative responses in the liver. However, the molecular mechanism(s) of the latter events remains unclear. In the present study, we examined TNF-alpha-induced genes in Hc human normal (unsensitized) hepatocytes by cDNA microarray analysis. Interleukin-8 (IL-8) induction was the most pronounced of the upregulated genes. The IL-8 protein level was also increased. IL-8 belongs to the ELR-CXC chemokine family and appears to exert mitogenic and antiapoptotic functions in other cell systems. IL-8 expression by TNF-alpha was inhibited when two survival signals, nuclear factor kappaB (NF-kappaB) and phosphatidylinositol 3-kinase (PI3K)/Akt, were inhibited by a mutant form of inhibitor of NF-kappaB (IkappaB); by dominant negative (kinase-dead) Akt; or by treatment with LY 294002, an inhibitor of PI3K. TNF-alpha induced apoptosis in Hc cells that were sensitized by inhibition of NF-kappaB and PI3K activation. IL-8 administration protected mice against concanavalin A-induced hepatitis in vivo. IL-8 also rescued the sensitized Hc cells, at least in part, from TNF-alpha-induced apoptosis in vitro. TNF-alpha inhibited DNA synthesis in unsensitized Hc cells in the absence of serum. Exogenous IL-8 reversed, though anti-IL-8 neutralization antibody enhanced, growth inhibition by TNF-alpha. These results indicate that IL-8, the production of which is stimulated by TNF-alpha, inhibits apoptosis of sensitized hepatocytes and releases normal (unsensitized) hepatocytes from growth inhibition induced by TNF-alpha. 相似文献