全文获取类型
收费全文 | 14215篇 |
免费 | 1330篇 |
国内免费 | 18篇 |
专业分类
耳鼻咽喉 | 157篇 |
儿科学 | 435篇 |
妇产科学 | 304篇 |
基础医学 | 1796篇 |
口腔科学 | 289篇 |
临床医学 | 1757篇 |
内科学 | 2864篇 |
皮肤病学 | 219篇 |
神经病学 | 1387篇 |
特种医学 | 570篇 |
外科学 | 2015篇 |
综合类 | 269篇 |
一般理论 | 12篇 |
预防医学 | 1427篇 |
眼科学 | 307篇 |
药学 | 947篇 |
中国医学 | 18篇 |
肿瘤学 | 790篇 |
出版年
2021年 | 214篇 |
2020年 | 129篇 |
2019年 | 214篇 |
2018年 | 265篇 |
2017年 | 213篇 |
2016年 | 237篇 |
2015年 | 237篇 |
2014年 | 318篇 |
2013年 | 497篇 |
2012年 | 661篇 |
2011年 | 679篇 |
2010年 | 367篇 |
2009年 | 394篇 |
2008年 | 616篇 |
2007年 | 670篇 |
2006年 | 717篇 |
2005年 | 622篇 |
2004年 | 605篇 |
2003年 | 528篇 |
2002年 | 504篇 |
2001年 | 488篇 |
2000年 | 477篇 |
1999年 | 402篇 |
1998年 | 149篇 |
1997年 | 144篇 |
1996年 | 121篇 |
1995年 | 130篇 |
1994年 | 117篇 |
1993年 | 99篇 |
1992年 | 283篇 |
1991年 | 292篇 |
1990年 | 328篇 |
1989年 | 279篇 |
1988年 | 234篇 |
1987年 | 230篇 |
1986年 | 245篇 |
1985年 | 221篇 |
1984年 | 194篇 |
1983年 | 159篇 |
1982年 | 121篇 |
1979年 | 151篇 |
1978年 | 128篇 |
1977年 | 121篇 |
1976年 | 132篇 |
1975年 | 97篇 |
1974年 | 127篇 |
1973年 | 99篇 |
1972年 | 118篇 |
1971年 | 98篇 |
1970年 | 103篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
Ventromedial tegmental lesions abolish offense without disturbing predation or defense 总被引:1,自引:0,他引:1
D B Adams 《Physiology & behavior》1986,38(2):165-168
Offense, defense, and predation, three kinds of aggressive behavior, are differentially affected by lesions of the ventromedial tegmentum of the brainstem of the rat. The lesions abolish offense while leaving defense and predation undisturbed. The offense behavior against another strange male, including bite-and-kick attack, offensive sideways posture, and offensive upright posture, was totally abolished, while the rats showed intact motor patterns of defensive upright posture, chasing, and killing bite in the tests for defense and predation. It is argued that these results support a motivational systems analysis of mammalian aggressive behavior. According to such an analysis, offense, defense, and predation are controlled by discrete motivational mechanisms located in different brainstem regions. 相似文献
82.
Thomas Adams William S. Spielman Kenneth R. Holmes S. R. Heisey Michael M. Chen 《Annals of biomedical engineering》1985,13(3-4):237-258
The kidney, with its heterogeneous regional perfusion in the two anatomically and functionally distinct vascular beds of the
renal cortex and medulla, and with its nonuniform blood vessel geometries, presents a unique challenge for measuring intrarenal
blood flow distribution. Determining whole organ perfusion, on the other hand, is comparatively simple for the kidney, but
it provides relatively little information about the suspected dependency of renal excretory function on local perfusion rate.
Among the variety of methods proposed for gauging regional renal blood flow, some depend on measuring one or more of the tissue's
thermal properties. The most straightforward, but least reliable, involve measurements either of focal tissue temperature
alone, or of regional tissue thermal gradients. Simply using heat as a diffusible indicator, however, is unreliable as a measure
of blood flow, for many of the same reasons that using an inert gas in a dilution technique is unreliable. Recently developed
thermal analytical methods, though, hold promise for measuring local tissue blood flow with accuracy and precision. Two of
them are reviewed here. One depends on measurement of the effective thermal conductivity of a small mass of tissue by evaluating
the steady state ratio between regional unidirectional heat flux across it and the associated temperature gradient in one
vector along a segment of it through an imposed spheroidal heat field. The other depends on analyses of tissue temperature
decay subsequent to a controlled pulse of heat delivered through a small inserted thermistor bead. Both techniques use bioheat
transfer equations to deduce regional blood flow
Research by K.R. Holmes and M.M. Chen was supproted by NIH-NHLBI Grant HL27011, that by T. Adams and S.R. Heisey through the
Michigan Heart Association, and that by W.S. Spielman through a grant from the NSF (PCM 8110588) who is a recipient of NIH
Research Career Development Award HL01010. 相似文献
83.
Structure of an autoimmune T cell receptor complexed with class II peptide-MHC: insights into MHC bias and antigen specificity 总被引:1,自引:0,他引:1
Maynard J Petersson K Wilson DH Adams EJ Blondelle SE Boulanger MJ Wilson DB Garcia KC 《Immunity》2005,22(1):81-92
T cell receptor crossreactivity with different peptide ligands and biased recognition of MHC are coupled features of antigen recognition that are necessary for the T cell's diverse functional repertoire. In the crystal structure between an autoreactive, EAE T cell clone 172.10 and myelin basic protein (1-11) presented by class II MHC I-Au, recognition of the MHC is dominated by the Vbeta domain of the TCR, which interacts with the MHC alpha chain in a manner suggestive of a germline-encoded TCR/MHC "anchor point." Strikingly, there are few specific contacts between the TCR CDR3 loops and the MBP peptide. We also find that over 1,000,000 different peptides derived from combinatorial libraries can activate 172.10, yet the TCR strongly prefers the native MBP contact residues. We suggest that while TCR scanning of pMHC may be degenerate due to the TCR germline bias for MHC, recognition of structurally distinct agonist peptides is not indicative of TCR promiscuity, but rather highly specific alternative solutions to TCR engagement. 相似文献
84.
Adams AK Talman EA Campbell L McIlroy BK Moore MA 《Journal of biomedical materials research》2001,57(4):582-587
Bovine pericardial and porcine valve materials stabilized by dye-mediated photooxidation have shown potential for bioprosthetic valve use. Previously, in vitro and in vivo stability of these materials was demonstrated through enzymatic, chemical, extraction, rat subcutaneous, and functional challenges. Here, we examine the stability of photooxidized porcine aortic valves through amino acid, crosslink, and hydrothermal isometric tension analysis. Photooxidation reduced intact histidine residues from 17.0 to 0 residues per 1000, indicating the photooxidative alteration of this amino acid. Diphenyl borinic acid-derivitized hydrolyzates of proteins were separated by high-performance liquid chromatography, which identified several amino acid crosslinks that appeared with photooxidation that were absent in untreated controls. Thermal relaxation analysis indicated a significantly higher (p < 0.0002) thermal stability for photooxidized porcine cusps than that of untreated controls, with mean relaxation times for untreated cusps of 14,000 +/- 4650 versus 22,900 +/- 2480 s for photooxidized cusps. In summary, porcine aortic valve tissue treated by dye-mediated photooxidation contains new chemical species and exhibits properties consistent with intermolecular crosslink formation, which explain the increased biostability of this material and its potential for use in bioprosthetic devices. 相似文献
85.
86.
Adams RJ Fuhlbrigge AL Finkelstein JA Weiss ST 《The Journal of allergy and clinical immunology》2002,109(4):636-642
87.
Immune responses of goats persistently infected with caprine arthritis-encephalitis virus. 总被引:3,自引:3,他引:3 下载免费PDF全文
D S Adams T B Crawford K L Banks T C McGuire L E Perryman 《Infection and immunity》1980,28(2):421-427
Eight cesarean-derived goat kids were inoculated with caprine arthritis-encephalitis virus (CAEV), and proliferative responses of their peripheral blood mononuclear cells to mitogens and CAEV antigen were monitored for 9 months. Antibody specific for CAEV was measured by an enzyme-linked immunosorbent assay. Five cesarean-derived noninfected goats were tested simultaneously. Significant differences between the infected and control mononuclear cell proliferation reactions to CAEV began 14 days post-inoculation and continued in a fluctuant manner until 134 days post-inoculation. The magnitude of the proliferative reaction steadily increased in infected goats until the end of the experiment at 271 days post-inoculation. Responses to mitogens were not significantly different between infected and control goats. Virus-inoculated goats produced CAEV-specific antibody that reached a maximum level between 49 and 77 days post-inoculation and then declined to lower levels through 271 days post-inoculation. The virus-inoculated goats developed mild but characteristic clinical evidence of caprine arthritis-encephalitis, and CAEV was reisolated from four goats at 286 days post-inoculation. The five control goats developed neither an anti-CAEV immune response nor clinical disease, and CAEV could not be reisolated from them. 相似文献
88.
SspA is required for lethal Salmonella enterica serovar Typhimurium infections in calves but is not essential for diarrhea 下载免费PDF全文
Tsolis RM Adams LG Hantman MJ Scherer CA Kimbrough T Kingsley RA Ficht TA Miller SI Bäumler AJ 《Infection and immunity》2000,68(6):3158-3163
Salmonella pathogenicity island 1 (SPI-1) encodes virulence determinants, which are important for enteropathogenicity in calves. To determine whether the Salmonella enterica serovar Typhimurium SPI-1 effector proteins SspA and SptP are important for enteropathogenicity, strains lacking these proteins were tested during oral infection of calves. Calves infected with a sptP mutant or its isogenic parent developed diarrhea and lethal morbidity. In contrast, calves infected with an sspA mutant developed diarrhea, which resolved within 10 days but did not result in mortality. The sspA mutant was recovered from bovine intestinal tissues at numbers similar to those obtained for its isogenic parent and caused marked intestinal lesions. Thus, the severity of pathological changes caused by serovar Typhimurium strains or their ability to cause diarrhea were not predictive of their ability to cause lethal morbidity in calves. We conclude that factors other than or in addition to bacterial colonization, intestinal lesions, or electrolyte loss contribute to lethal morbidity in calves infected with serovar Typhimurium. 相似文献
89.
S G Hübscher D H Adams J A Buckels P McMaster J Neuberger E Elias 《Journal of clinical pathology》1989,42(4):360-370
Six of the first 85 patients who received the first 100 liver transplantations carried out in Birmingham developed a syndrome of fulminant liver failure with distinctive clinical and pathological features. The typical clinical presentation was of an uneventual initial postoperative period, followed by a sudden deterioration in graft function, progressing rapidly to graft failure. All six patients died. The characteristic pathological changes were those of massive haemorrhage and hepatocyte necrosis with only mild inflammation and without occlusive lesions in large arteries or veins. These distinctive features differed from other recognised patterns of graft damage and seemed to comprise a specific post-transplant syndrome. The pathogenesis was not clear and in the absence of any definite aetiology it is suggested that the term "massive haemorrhagic necrosis" be used to describe these cases. Additional findings seen in five of the six cases were venoocclusive lesions (n = 4) and a combination of ductopenia and foam cell arteriopathy (n = 2). The presence of these associated lesions suggests that there may be an overlap with other types of graft damage. 相似文献
90.
Stenoien DL Cummings CJ Adams HP Mancini MG Patel K DeMartino GN Marcelli M Weigel NL Mancini MA 《Human molecular genetics》1999,8(5):731-741
Spinal bulbar muscular atrophy is a neurodegenerative disorder caused by a polyglutamine expansion in the androgen receptor (AR). We show in transiently transfected HeLa cells that an AR containing 48 glutamines (ARQ48) accumulates in a hormone-dependent manner in both cytoplasmic and nuclear aggregates. Electron microscopy reveals both types of aggregates to have a similar ultrastructure. ARQ48 aggregates sequester mitochondria and steroid receptor coactivator 1 and stain positively for NEDD8, Hsp70, Hsp90 and HDJ-2/HSDJ. Co-expression of HDJ-2/HSDJ significantly represses aggregate formation. ARQ48 aggregates also label with antibodies recognizing the PA700 proteasome caps but not 20S core particles. These results suggest that ARQ48 accumulates due to protein misfolding and a breakdown in proteolytic processing. Furthermore, the homeostatic disturbances associated with aggregate formation may affect normal cell function. 相似文献