全文获取类型
收费全文 | 7109篇 |
免费 | 428篇 |
国内免费 | 15篇 |
专业分类
耳鼻咽喉 | 60篇 |
儿科学 | 382篇 |
妇产科学 | 168篇 |
基础医学 | 798篇 |
口腔科学 | 129篇 |
临床医学 | 510篇 |
内科学 | 1531篇 |
皮肤病学 | 116篇 |
神经病学 | 356篇 |
特种医学 | 638篇 |
外科学 | 1279篇 |
综合类 | 156篇 |
一般理论 | 3篇 |
预防医学 | 274篇 |
眼科学 | 137篇 |
药学 | 539篇 |
1篇 | |
中国医学 | 7篇 |
肿瘤学 | 468篇 |
出版年
2023年 | 48篇 |
2022年 | 32篇 |
2021年 | 181篇 |
2020年 | 95篇 |
2019年 | 183篇 |
2018年 | 206篇 |
2017年 | 138篇 |
2016年 | 148篇 |
2015年 | 153篇 |
2014年 | 264篇 |
2013年 | 267篇 |
2012年 | 395篇 |
2011年 | 427篇 |
2010年 | 231篇 |
2009年 | 224篇 |
2008年 | 323篇 |
2007年 | 275篇 |
2006年 | 279篇 |
2005年 | 267篇 |
2004年 | 253篇 |
2003年 | 215篇 |
2002年 | 191篇 |
2001年 | 142篇 |
2000年 | 150篇 |
1999年 | 165篇 |
1998年 | 111篇 |
1997年 | 123篇 |
1996年 | 118篇 |
1995年 | 94篇 |
1994年 | 64篇 |
1993年 | 87篇 |
1992年 | 105篇 |
1991年 | 113篇 |
1990年 | 98篇 |
1989年 | 140篇 |
1988年 | 112篇 |
1987年 | 118篇 |
1986年 | 122篇 |
1985年 | 154篇 |
1984年 | 80篇 |
1983年 | 67篇 |
1982年 | 48篇 |
1981年 | 50篇 |
1980年 | 51篇 |
1978年 | 36篇 |
1977年 | 45篇 |
1976年 | 34篇 |
1975年 | 41篇 |
1974年 | 34篇 |
1973年 | 38篇 |
排序方式: 共有7552条查询结果,搜索用时 31 毫秒
41.
Chest radiographs and chest computed tomography (CT) scans were compared in 203 patients with newly diagnosed Hodgkin disease. The incidence of positive findings was tabulated from six intrathoracic lymph node groups, lung parenchyma, pericardium, pleura, and chest wall. The discordant cases were assessed to determine impact on clinical management. The CT scans provided additional evidence of disease involvement, ranging from 0% to 15% at each of the designated anatomic sites. Treatment was altered in 9.4% of all patients (19 of 203), including 13.8% (nine of 65) of those undergoing radiation therapy alone and 8.2% (ten of 122) of those undergoing combined-modality treatment. We conclude that routine chest CT examinations are valuable in the clinical management of those patients for whom radiation therapy is planned. 相似文献
42.
Esophageal diverticula are rarely found at the terminal portion, where they are called supradiaphragmatic or epiphrenic diverticula and occur in association with motility disorders of the terminal esophagus. We present here two cases of epiphrenic esophageal diverticulum, one of which was treated surgically. 相似文献
43.
Ross BD; Jacobson S; Villamil F; Korula J; Kreis R; Ernst T; Shonk T; Moats RA 《Radiology》1994,193(2):457
44.
45.
Early excision of deep burns has been advocated; however, it is difficult to clinically determine the depth of scald burns during the early postburn period. This prospective, randomized study was designed to determine whether early excision was superior to conservative treatment of scald injuries. Patients with scald injuries (which were not caused by grease) of clinically indeterminant depth were randomized to early (n = 12) or late (n = 12) excision; all patients with obvious superficial and full-thickness injuries were excluded. In the early excision group, all deep wounds were tangentially excised and grafted within 72 hours of admission, whereas in the late treatment group wounds were excised and grafted after 2 weeks had passed since injury. Area excised, postburn day of excision, percent graft take, operating-room time, blood replacement, incidence of infection, and length of hospital stay were compared. No patient experienced a significant wound infection or systemic sepsis. A significantly smaller area of excision was necessary for those patients who were treated with delayed surgery, and concomitant decreases in operating-room time and blood loss were observed. Notably, only one half of the patients who were randomized to the delayed excision group ultimately required surgical intervention to achieve wound closure. Graft take was comparable for both groups, as was length of hospital stay. Early clinical evaluation of scald injuries appears to be equivocal, and later evaluations reveal a less severe injury. Financial gains can be made when surgical excision of scald injuries is delayed until 2 weeks after injury because of a related reduction in hospital expenditures. 相似文献
46.
Vitrification technology has shown great promise for cryopreservation of human embryos. The majority of this work has been with blastocyst-stage embryos. This report describes initial clinical results following vitrification of human embryos on day 3 of culture at the 6- to 8-cell stage. A total of 236 embryos were cryopreserved on cryoloops using a vitrification protocol. Warmed embryos were cultured until day 5 before transfer to the patient. The post-warming survival rate was 85%. The clinical pregnancy rate was 44% (34/77), and the implantation rate was 20% (40/201). In transfers where at least one warmed embryo reached the blastocyst stage by the day of transfer, the clinical pregnancy rate was 58% (28/48). The cryoloop was an excellent vessel for ultra-rapid cryopreservation of embryos. This study supports the effectiveness of a dimethylsulphoxide/ethylene glycol cryoprotectant combination for vitrification of human embryos at the 6- to 8-cell stage. 相似文献
47.
Characterization of RAFTK, a novel focal adhesion kinase, and its integrin-dependent phosphorylation and activation in megakaryocytes 总被引:19,自引:3,他引:16
We have recently isolated a cDNA encoding a novel human intracellular tyrosine kinase, termed RAFTK (for a related adhesion focal tyrosine kinase). The RAFTK cDNA, which encodes a polypeptide of 1,009 amino acids, shares 65% homology to the focal adhesion kinase (FAK), including several consensus motifs. In this report, we describe the biochemical characterization and functional analysis of the RAFTK protein. Coexpression of RAFTK and FAK proteins in megakaryocytic cells and blood platelets was observed. Using a specific antibody to RAFTK and the monoclonal antibody 2A7 to FAK, FAK and RAFTK could be distinguished antigenically. RAFTK had intrinsic tyrosine kinase and autokinase activities. It was phosphorylated on tyrosine in growing cultures of COS cells transfected with the pCDNAIII/flag-RAFTK expression vector containing the RAFTK cDNA ligated with the 8 amino acid flag peptide sequence. Similar to FAK, dephosphorylation of RAFTK was observed when adherent transfected COS cells were detached. Phosphorylation was regained upon replating of these cells on the fibronectincoated dishes. Analysis of tyrosine-phosphorylated RAFTK from adherent transfected COS cells showed that the Src homology 2 (SH2) domains of the Src and Fyn protein kinases as well as the Grb2 adaptor protein were able to specifically associate with RAFTK. Tyrosine phosphorylation of endogenous RAFTK was observed upon fibronectin-induced activation of human megakaryocytic cells. Furthermore, colocalization of RAFTK protein with vinculin, a focal adhesion protein, was observed by confocal microscopy in focal adhesion- like structures in adherent CMK cells and in transfected pCDNAIII/flag- RAFTK COS cells upon fibronectin activation. These data suggest that RAFTK is a novel member of the FAK family, that it localizes to focal adhesion-like structures in CMK megakaryocytic cells, that it participates in integrinmediated signaling pathways in megakaryocytes, and that it is able to associate with the tyrosine kinases Src and Fyn as well as the adaptor protein Grb2 via SH2-phosphotyrosine interactions. 相似文献
48.
Studies of proteins that inhibit tissue factor activity have generally been conducted using either an extracted tissue homogenate ("thromboplastin") or tissue factor protein reconstituted into phospholipid vesicles rather than with tissue factor expressed in cell membranes (its physiological environment). In the present study, a human fibroblast cell strain was used to evaluate the effects of lipoprotein associated coagulation inhibitor (LACI), placental anticoagulant protein (PAP), and apolipoprotein A-II (apo A-II) on human tissue factor in cell membranes. LACI was tested from 7.8 to 500 pmol/L on fibroblasts cultured at cell densities ranging from 3,500 to 9,925 cells/well, and caused a progressive inhibition of tissue factor activity. PAP was tested from 3.9 nmol/L to 1 mumol/L at cell densities ranging from 4,500 to 15,400 cells/well and caused up to 83% inhibition of tissue factor activity. Inhibition by these proteins appeared to be influenced by cell density as well as whether the cells were intact or disrupted. Apo A-II, up to 1 mumol/L, did not inhibit the tissue factor activity of intact or disrupted fibroblasts at any cell density examined even though it did inhibit the activity of tissue factor in phospholipid vesicles. Of these inhibitors of tissue factor-dependent activation of factor X, LACI was the most effective in suppressing the generation of factor Xa activity. The effects obtained with apo A-II are clearly dependent on the nature of the tissue factor preparation with which it is tested. The disparity between the inhibitory effect of apo A-II on the activity of tissue factor reconstituted into lipid vesicles and the absence of effect on the activity of tissue factor remaining in cell membranes serves to reemphasize the necessity of reexamining results obtained with model systems using as nearly physiological reagents as possible. 相似文献
49.
Monocyte chemoattractant protein-1 (MCP-1) is a pivotal mediator of angiocentric granuloma formation in glucan-induced pulmonary granulomatous vasculitis. Based on the rationale that mononuclear phagocytes retrieved from granulomas are rich sources of nitric oxide (NO) and that the recruitment of mononuclear phagocytes into lesions abates as granuloma formation slows, we tested the hypothesis that MCP-1 gene expression is regulated by a NO-sensitive mechanism. Preexposure of endothelial cell (EC) monolayers to NO donor compounds markedly reduced cytokine-induced MCP-1 expression and cytosolic-to-nuclear translocation of nuclear factor-kappa B (NF-B), reversed fluctuations in endothelial reduced glutathione (GSH) pools but did not affect cGMP concentrations. The lungs of mice bearing targeted disruptions of the inducible nitric oxide synthase (iNOS) gene exhibited significantly higher concentrations of MCP-1 following glucan infusion than did those of wild-type mice. Cumulatively, these data suggest that NO suppresses MCP-1 expression by blunting the redox changes associated with cytokine-induced EC activation. 相似文献
50.