全文获取类型
收费全文 | 38517篇 |
免费 | 4177篇 |
国内免费 | 2614篇 |
专业分类
耳鼻咽喉 | 420篇 |
儿科学 | 704篇 |
妇产科学 | 653篇 |
基础医学 | 3884篇 |
口腔科学 | 603篇 |
临床医学 | 4663篇 |
内科学 | 5299篇 |
皮肤病学 | 416篇 |
神经病学 | 1906篇 |
特种医学 | 1345篇 |
外国民族医学 | 16篇 |
外科学 | 4544篇 |
综合类 | 7125篇 |
现状与发展 | 10篇 |
一般理论 | 2篇 |
预防医学 | 3292篇 |
眼科学 | 710篇 |
药学 | 4078篇 |
43篇 | |
中国医学 | 2535篇 |
肿瘤学 | 3060篇 |
出版年
2024年 | 189篇 |
2023年 | 723篇 |
2022年 | 1775篇 |
2021年 | 2274篇 |
2020年 | 1727篇 |
2019年 | 1396篇 |
2018年 | 1472篇 |
2017年 | 1462篇 |
2016年 | 1312篇 |
2015年 | 2013篇 |
2014年 | 2413篇 |
2013年 | 2500篇 |
2012年 | 3293篇 |
2011年 | 3407篇 |
2010年 | 2348篇 |
2009年 | 1830篇 |
2008年 | 2103篇 |
2007年 | 1990篇 |
2006年 | 1836篇 |
2005年 | 1627篇 |
2004年 | 1115篇 |
2003年 | 1064篇 |
2002年 | 930篇 |
2001年 | 757篇 |
2000年 | 666篇 |
1999年 | 558篇 |
1998年 | 250篇 |
1997年 | 311篇 |
1996年 | 212篇 |
1995年 | 208篇 |
1994年 | 197篇 |
1993年 | 118篇 |
1992年 | 171篇 |
1991年 | 162篇 |
1990年 | 148篇 |
1989年 | 117篇 |
1988年 | 124篇 |
1987年 | 93篇 |
1986年 | 69篇 |
1985年 | 59篇 |
1984年 | 44篇 |
1983年 | 32篇 |
1982年 | 21篇 |
1981年 | 18篇 |
1980年 | 21篇 |
1979年 | 21篇 |
1978年 | 13篇 |
1974年 | 13篇 |
1971年 | 11篇 |
1970年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Inhibition of experimental autoimmune tubulointerstitial nephritis in Brown-Norway rats by (15S)-15-methyl prostaglandin E1. Analysis of the effect of prostaglandin E1 on the induction of the humoral immune response and the elicitation of humorally mediated inflammation. 下载免费PDF全文
Brown-Norway (BN) rats develop tubulointerstitial nephritis (TIN) after immunization with bovine tubular basement membrane (TBM) and adjuvants. Daily subcutaneous injections (either on Days 0-7 or Days 0-14) of (15S)-15-methyl prostaglandin E1 (M-PGE1) at a dose of 1 mg/kg/day markedly inhibited or completely abrogated the development of both the acute polymorphonuclear (Day 10) and the subsequent mononuclear (Day 14) inflammatory phases of BN rat TIN. Circulating anti-TBM antibody in Days 0-7 M-PGE1-treated rats was moderately diminished on Day 8 after immunization but not on Day 14. Circulating anti-TBM antibody in Days 0-14 M-PGE1-treated rats was only slightly diminished on Day 14. In experiments to test the effect of M-PGE1 on the elicitation phase of humorally mediated inflammation, M-PGE1 inhibited the acute inflammatory response observed 6 hours after intradermal injection of particulate TBM into TBM-sensitized BN rats. The inflammation in these skin tests was demonstrated by passive transfer experiments to be humorally mediated. The inhibition of acute humorally mediated intradermal inflammation was not attributable to neutropenia, because M-PGE1 caused a significant neutrophilia as demonstrated by peripheral blood smears. Although the inhibition of TIN in Days 0-14 M-PGE1-treated rats may have been due, in part, to dysfunction of the elicitation phase of humorally mediated inflammation, the inhibition of TIN in Days 0-7 M-PGE1-treated rats was more likely secondary to the diminished induction of either humoral or cellular immunity. 相似文献
102.
Umbilical cord blood transplantation in adults using myeloablative and nonmyeloablative preparative regimens. 总被引:3,自引:0,他引:3
Unrelated umbilical cord blood (UCB) transplantation has recently been explored in an increasing number of adult patients. The relative ease of procurement and the lower-than-anticipated risk of severe acute graft-versus-host disease has made UCB transplantation an appealing alternative to bone marrow-derived hematopoietic stem cells. The use of reduced-intensity or nonmyeloablative preparative regimens to allow engraftment of UCB broadens the scope of patients who may benefit from allogeneic immunotherapy, including elderly and medically infirm patients with no matched sibling donor. This review summarizes the available data on the use of UCB as an alternative source of hematopoietic stem cell transplantation in adult patients. 相似文献
103.
The specific recognition between asialoglycoprotein receptor and galactose ligand at cell-substrate interfaces has been shown to mediate hepatocyte adhesion and maintain liver specific functions of hepatocytes. Conventionally, the success of hepatocyte attachment on engineered tissue scaffold is inferred from the degree of two-dimensional cell spreading that is measured by transmitted light microscopy. However, the actual contact mechanics and adhesion strength of hepatocytes during two-dimensional cell spreading has not been elucidated due to lack of biophysical probe. In this study, a novel biophysical technique known as confocal reflectance interference contrast microscopy (C-RICM) in conjunction with phase contrast microscopy is utilized to probe the adhesion dynamics, contact mechanics and two-dimensional spreading kinetics of HepG2 cells on galactose immobilized and collagen gel coated substrates. C-RICM demonstrates that HepG2 cells form strong adhesion contacts with both galactose-immobilized surfaces and collagen gel coated substrates. Moreover, HepG2 cells maintain their compact shapes in the presence of asialoglycoprotein receptor-mediated recognition while they become exceedingly spread under integrin-mediated adhesion on collagen gel coated substrate. The initial rate of adhesion contact formation and the steady-state adhesion energy of HepG2 cell population are highest on substrate conjugated with galactose ligand via a longer spacer. The adhesion dynamics and final adhesion energy of HepG2 cells depends both on the type of ligand-receptor interaction and the length of spacer between the ligand and substrate. Most importantly, new biophysical insights into the initial hepatocyte attachment that are critical for hepatocyte culture are provided through the decomposition of two-dimensional spreading and adhesion contact formation on bio-functional substrates. 相似文献
104.
105.
Bruce Ho PhD Woodrew Chao Reza Sadri Lu Huang Ricky Taira Henry Shih 《Journal of digital imaging》1995,8(4):180-190
A key advantage in the conversion from film-based to digital radiology is the possibility of a long-term on line electronic archival of patient studies. The popular approach based on optical disk jukeboxes for the long-term archive and magnetic disk storage for data caching is not economically attractive because of the cost of both the jukebox and the medium. Strategies for extending the archival system design with a tape jukebox have been studied. The proposed strategy calls for the use of high-ratio lossy compression together with low-cost tape storage to make long-term on line archiving more affordable. An intelligent prefetching algorithm based on hospital information system and radiologic information system triggers, which in turn are augmented by manual case preparation, can effectively overcome the longer latency of ad hoc retrievals. This longer latency is caused by both system-level bottlenecks and the sequential access constraint of the tape drive. Strategies for image clustering and tape allocation by patient classification also enhance retrieval efficiency. This archival design using image compression, prefetching, and clustering could be implemented in many of the existing teleradiology and picture archiving and communication systems. 相似文献
106.
Lung preservation solution substrate composition affects rat lung oxidative metabolism during hypothermic storage 总被引:1,自引:0,他引:1
Peltz M Hamilton TT He TT Adams GA Koshy S Burgess SC Chao RY Jessen ME Meyer DM 《Respiratory physiology & neurobiology》2005,148(3):2771-283
Lungs harvested for transplantation utilize oxygen after procurement. We investigated the effects of storage solution substrate composition on pulmonary oxidative metabolism and energetics during the preservation interval. Rat lungs were harvested and stored at 10 degrees C in low-potassium dextran (LPD) solution. Groups of lungs were preserved with preservation solution containing 5mM carbon-13 ((13)C) labeled glucose or increasing concentrations of (13)C labeled pyruvate. Additional groups of rat lungs were studied with dichloroacetate (DCA) added to the pyruvate-modified preservation solutions. Oxidative metabolism (measured by (13)C-enrichment of glutamate) and adenine nucleotide levels were quantified. Increasing preservation solution pyruvate concentration augmented glutamate (13)C-enrichment up to a concentration of 32mM pyruvate. DCA further stimulated oxidative metabolism only at lower concentrations of pyruvate (4 and 8mM). ATP and ADP were not different among groups, but AMP levels were higher in the glucose group. These data suggest that altering the substrate composition of the preservation solution influences lung metabolism during allograft preservation for transplantation. 相似文献
107.
Evidence for platelet-activating factor as a late-phase mediator of chronic pancreatitis in the rat. 总被引:3,自引:0,他引:3 下载免费PDF全文
W. G. Zhou W. Chao B. A. Levine M. S. Olson 《The American journal of pathology》1990,137(6):1501-1508
The role of platelet-activating factor (PAF) as a mediator of pancreatic inflammation was examined in the rat pancreatic duct ligation model of obstructive pancreatitis. Pancreatic generation of PAF, as measured by bioassay (ie, platelet [3H]serotonin secretion), was determined at various times after induction of inflammation. Tissue levels of PAF in the normal pancreas averaged 600 +/- 49 pg/g, but PAF was not detectable during the initial 24 hours of pancreatitis, a time when the inflammatory reaction would be considered acute, that is, during the period of maximal serum amylase release and the development of interstitial edema. However a substantial increase in pancreatic PAF levels (12 times control levels) was observed 7 to 14 days after duct ligation during the late-phase response interval similar to the situation characteristic of chronic pancreatitis in which parenchymal atrophy, fibrosis, and pancreatic insufficiency evolve. One week after duct ligation when PAF levels peaked, an evaluation was made of the effects of PAF antagonists (BN52021 and WEB2170) on pancreatic lesions using Evan's blue extravasation, pancreatic myeloperoxidase (MPO) activity, and acid phosphatase activity in peritoneal lavage fluid. BN52021 or WEB2170 treatment was shown to reduce pancreatic damage and inflammation significantly. Long-term in vivo administration of exogenous PAF (20 micrograms/kg/hr for 7 days) exhibited a reduction of [3H]thymidine uptake into and amylase release from pancreatic acini in vitro. Our observations 1) that pancreatic PAF levels increased significantly during the chronic phase of obstructive pancreatitis induced by duct ligation; 2) that inhibition of the action of PAF, through specific receptor antagonism, caused an attenuation of pancreatic lesions; and 3) that chronic administration of PAF resulted in decreased pancreatic regeneration and exocrine function are consistent with a pivotal role for PAF as a late-phase inflammatory mediator in chronic pancreatitis in rats. 相似文献
108.
Ching-Yu Lin Angel Chao Yuh-Cheng Yang Hung-Hsueh Chou Chih-Ming Ho Ruey-Wen Lin Ting-Chang Chang Jia-Yia Chiou Fang-Yu Chao Kung-Liahng Wang Tsai-Yen Chien Swei Hsueh Chu-Chun Huang Chien-Jen Chen Chyong-Huey Lai 《Journal of clinical virology》2008,42(4):361-367
BACKGROUND: Type-specific persistence of human papillomavirus (HPV) infection can cause invasive cervical cancer. OBJECTIVES: To evaluate the efficacy of HPV detection and typing with a general polymerase chain reaction (PCR)-based genotyping array and to compare it with a type-specific PCR assay. STUDY DESIGN: Four hundred and thirty-three cervical samples were tested with a modified MY11/GP6+ PCR-based reverse-blot assay (EasyChip HPV Blot; King Car, Taiwan [hereafter HPV Blot]) and with 20 genotypes of L1-type-specific PCR (HPV-6, -11, -16, -18, -31, -33, -35, -39, -45, -51, -52, -53, -56, -58, -59, -62, -66, -68, -70, and -71 [CP8061]). RESULTS: The concordance of the two tests in determining HPV positivity was 96.8% (419/433), with a Cohen's kappa=0.93 (95% CI: 0.90-0.97) and McNemar's test of P=1.0, which indicates excellent agreement. The overall concordance of the two tests in the identification of type-specific HPV was 91.0% (394/433). Sensitivity (90-100%), specificity (99.2-100%), and accuracy (98.6-100%) rates of HPV Blot against the gold standard were satisfactory for HPV-16, -18, -58, -33, -52, -39, -45, -31, -51, -70 while HPV-71 (63.6%) had suboptimal sensitivity. Though the kappa values between the two tests for many individual genotypes could not be reliably calculated because of low positivity, the kappa values for HPV-16, -52, and -58 were excellent (0.93, 0.96, and 0.95, respectively). CONCLUSION: The modified MY11/GP6+ PCR-based HPV Blot assay is accurate and sensitive for detection and genotyping of HPV in cervical swab samples. 相似文献
109.
Dendritic cells (DC) are specialized antigen-presenting cells. DC can acquire and process antigens in the periphery before maturing and migrating to secondary lymphoid tissues where they present the antigens and deliver co-stimulatory signals to T cells. We describe an immunostimulatory oligonucleotide containing a CpG motif that stimulated murine DC to up-regulate co-stimulatory molecules, induce T-cell proliferative responses and secrete interleukin-12 in vitro. Administration of this oligonucleotide, but not of a control oligonucleotide lacking this motif, to mice led to the disappearance of DC from the marginal zone and T-cell areas of spleen, but not from heart or kidney. The same CpG did not cause maturation of monocyte-derived human DC in vitro, but lipopolysaccharide-treated monocyte-derived DC showed enhanced functional activity and up-regulated co-stimulatory molecules. 相似文献
110.
目的 了解长沙地区无偿献血人群隐匿性乙型肝炎病毒感染(occult hepatitis B virus infection,OBI)流行情况,探讨HBV基因型分布特征和S区氨基酸突变的情况。方法 对长沙地区检测结果为HBsAg-/HBV DNA+的无偿献血血液样本进行HBV血清标志物检测,对其中的OBI样本进行HBV病毒载量检测和S区基因扩增,分析血清学标志物抗HBs与病毒载量检出与否的关系,并对扩增产物进行HBV基因分型和突变位点分析。结果 2019年1月—2020年1月长沙地区173 893份无偿献血标本共确认58例OBI样本,OBI流行率为0.033%;共发现7种血清学模式,抗HBc单独阳性最多,占38.98%,所有样本中抗HBc阳性率为89.83%;16例样本能检测出病毒载量,其中14例样本浓度小于100 IU/ml;抗HBs阳性组和阴性组间的病毒载量检出率无统计学差异;75.0%(12/16)样本扩增出S区序列,基因型均为B型,均发生突变,其中11例的HBsAg抗原决定簇及周边主要亲水区域(major hydrophilic region, MHR)发生氨基酸突变。结论 长沙地区无偿献血者中的OBI感染率在全国属于偏低水平;HBV基因型主要是B型,MHR区的氨基酸突变可能是造成OBI的原因,突变有本地特点。 相似文献