全文获取类型
收费全文 | 7570篇 |
免费 | 611篇 |
国内免费 | 19篇 |
专业分类
耳鼻咽喉 | 94篇 |
儿科学 | 172篇 |
妇产科学 | 230篇 |
基础医学 | 1112篇 |
口腔科学 | 181篇 |
临床医学 | 751篇 |
内科学 | 1486篇 |
皮肤病学 | 199篇 |
神经病学 | 693篇 |
特种医学 | 408篇 |
外科学 | 1047篇 |
综合类 | 96篇 |
一般理论 | 2篇 |
预防医学 | 500篇 |
眼科学 | 219篇 |
药学 | 610篇 |
中国医学 | 18篇 |
肿瘤学 | 382篇 |
出版年
2023年 | 48篇 |
2022年 | 64篇 |
2021年 | 126篇 |
2020年 | 88篇 |
2019年 | 126篇 |
2018年 | 164篇 |
2017年 | 117篇 |
2016年 | 114篇 |
2015年 | 133篇 |
2014年 | 172篇 |
2013年 | 319篇 |
2012年 | 337篇 |
2011年 | 328篇 |
2010年 | 214篇 |
2009年 | 175篇 |
2008年 | 284篇 |
2007年 | 326篇 |
2006年 | 293篇 |
2005年 | 273篇 |
2004年 | 278篇 |
2003年 | 260篇 |
2002年 | 262篇 |
2001年 | 248篇 |
2000年 | 254篇 |
1999年 | 198篇 |
1998年 | 100篇 |
1997年 | 106篇 |
1996年 | 64篇 |
1995年 | 91篇 |
1994年 | 81篇 |
1993年 | 68篇 |
1992年 | 177篇 |
1991年 | 200篇 |
1990年 | 162篇 |
1989年 | 156篇 |
1988年 | 155篇 |
1987年 | 173篇 |
1986年 | 158篇 |
1985年 | 155篇 |
1984年 | 122篇 |
1983年 | 100篇 |
1982年 | 77篇 |
1981年 | 60篇 |
1980年 | 65篇 |
1979年 | 113篇 |
1978年 | 81篇 |
1977年 | 67篇 |
1976年 | 62篇 |
1975年 | 52篇 |
1974年 | 46篇 |
排序方式: 共有8200条查询结果,搜索用时 31 毫秒
101.
Larsen LA Svendsen IH Jensen AM Kanters JK Andersen PS Møller M Sørensen SA Sandøe E Jacobsen JR Vuust J Christiansen M 《Clinical genetics》2000,57(2):125-130
In a four-generation family with long QT syndrome, syncopes and torsades de pointes ventricular tachycardia (TdP) were elicited by abrupt awakening in the early morning hours. The syndrome was associated with a novel KCNH2 missense mutation, G572R, causing the substitution of a glycine residue at position 572, at the end of the S5 transmembrane segment of the HERG K(+)-channel, with an arginine residue. This segment is involved in the channel pore and the mutation may cause a reduction in the rapidly activating delayed rectifier K+ current (Ikr), or changed gating properties of the ion channel, leading to prolonged cardiac repolarization. The electrocardiograms of affected persons showed prolonged QT interval and notched T waves. Despite treatment with atenolol, 200 mg twice daily, the proband still experienced TdP episodes. Three untreated relatives of the proband died suddenly, and unexpectedly, at 18, 32, and 57 years of age. The G572R mutation is thus associated with a high mortality rate, and the clinical presentation illustrates that some mutations may not be controllable by just beta-blockade. 相似文献
102.
Anton Brøgger Trygve Urdal Finn Brasch Larsen Nils Johan Lavik 《Clinical genetics》1977,11(4):349-358
Y chromosome variation has been studied in three groups of Norwegian males: 35 boys from an adolescent psychiatric hospital; 45 men from a hospital for hard-to-manage or dangerous, psychotic men; and 26 boys from two ordinary school classes.
Y chromosomes with 1, 2, and 3 brightly fluorescing bands were found in all three groups. One boy carried a Y with no bands. The mean values of the Yf/Yq ratio were not significantly different in the three groups (Yf is the length of the distal, brightly fluorescing part of Yq). Two cases of XY/XYY mosaicism were found among the psychotic men.
The study shows that the human species is polymorphic with regard to the size of the Y chromosome, i. e. the number of fluorescent bands in the long arm. No phenotypical manifestation of this polymorphism, particuIarly as regards behaviour, was found. 相似文献
Y chromosomes with 1, 2, and 3 brightly fluorescing bands were found in all three groups. One boy carried a Y with no bands. The mean values of the Yf/Yq ratio were not significantly different in the three groups (Yf is the length of the distal, brightly fluorescing part of Yq). Two cases of XY/XYY mosaicism were found among the psychotic men.
The study shows that the human species is polymorphic with regard to the size of the Y chromosome, i. e. the number of fluorescent bands in the long arm. No phenotypical manifestation of this polymorphism, particuIarly as regards behaviour, was found. 相似文献
103.
For most autoimmune disorders, the pattern of inheritance is very complex. The major histocompatibility complex (MHC) gene complex has been implicated as the major genetic component in the predisposition to these diseases but other genes are likely to be involved. Based on function and experimental data, the gene encoding cytotoxic T lymphocyte-associated antigen 4 (CTLA4) has been suggested as a candidate gene for conferring susceptibility to autoimmunity. In this review, we critically evaluate the evidence for pathogenetical involvement of CTLA-4 in the different autoimmune diseases with focus on the possible role of genetic variation of the CTLA4 locus. 相似文献
104.
Cloning and expression of the gene involved in Sanfilippo B syndrome (mucopolysaccharidosis III B) 总被引:4,自引:1,他引:4
Sanfilippo B syndrome is caused by a deficiency of alpha-N-
acetylglucosaminidase, a lysosomal enzyme involved in the degradation of
heparan sulphate. Accumulation of the substrate in lysosomes results in
degeneration of the central nervous system with progressive dementia often
combined with hyperactivity and aggressive behaviour. In order to clone the
deficient gene, we purified the enzyme from human placenta and obtained
amino acid sequence information. Alignment of one of the CNBr generated
internal peptides to sequence from the database revealed the chromosomal
location of the gene in the 5' upstream flanking region of the gene for
17-beta-hydroxysteroid-dehydrogenase at 17q21.1. The available DNA sequence
was used to clone the cDNA coding for alpha-N- acetylglucosaminidase and
analyse its gene structure. The gene is fully contained in the 5' upstream
flanking region of the gene for 17-beta- hydroxysteroid-dehydrogenase and
interrupted by five introns. The cDNA clone has a length of 2575 bp and
encodes a protein of 743 amino acids. Chinese hamster ovary cells
transfected with the cDNA construct show alpha-N-acetylglucosaminidase
activity about 17-fold over background. This will allow correction studies
with NAG deficient Sanfilippo B cell lines and facilitate the development
of enzyme replacement therapy for these patients.
相似文献
105.
D Barbieri-Weill D Mathieu-Mahul F Gay J Robert-Lezenes F Moreau-Gachelin F Wendling C Lacombe N Casadevall P Tambourin C J Larsen 《Virology》1983,128(1):234-239
A Friend mink cell focus-inducing (Fr-MCF) virus isolated from a Friend tumor cell line was able to induce acute erythroleukemia associated with polycythemia when injected as a Friend murine ecotropic leukemia virus (F-MuLV) pseudotype into adult Swiss and ICFW mice. One virus isolate recovered from leukemic cells and designated as FV-F3 presented the following properties: (i) persistence of the same leukemogenic power when propagated in vivo and in vitro; (ii) in vivo spleen focus-forming (SFFV) capacity; (iii) presence of erythropoietin (EPO)-independent CFU-E in leukemic animals; (iv) expression of a 32 RNA specifically recognized by a SFFV probe, in FV-F3 infected cells; and (v) expression in FV-F3-infected cell of polypeptides in the range of gp52 SFFV. Peptide analysis of these products revealed close similarities with the parental MCF virus. These data suggest that a SFFV genome arose by genetic recombinational events involving MCF virus. 相似文献
106.
Joachim Saloga Gideon Lack Kathrine Bradley Harald Renz Gary Larsen Donald Y. M. Leung Erwin W. Gelfand 《European journal of immunology》1994,24(12):3140-3147
We investigated the ability of staphylococcal enterotoxin B (SEB) to modify the immediate hypersensitivity response induced in BALB/c mice following sensitization to ovalbumin (OVA), a response mediated by OVA-reactive Vβ8 T cells. Mice were sensitized by skin painting with OVA every second day over a period of 2 weeks. SEB, a potent activator of Vβ8+ T cells, was administered at the same site where OVA was applied (skin of the lower abdomen) following two different protocols. In protocol (A) SEB was injected intradermally 1 day before painting with OVA and on day 7; in protocol B, SEB was injected each time OVA was applied to the skin (eight times). SEB (but not SEA) altered the development of immediate hypersensitivity to OVA, as demonstrated by the reduction in allergen-specific IgE, decreased OVA-specific immediate skin test responsiveness, and prevented the development of increased airways responsiveness after bronchial challenge with OVA. Injections of SEB did not alter the proliferative responses of local draining lymph node cells or spleen mononuclear cells to OVA, indicating that administration of SEB did not inhibit the sensitization to OVA, but shifted the immune response away from an immediate type response (IgE/IgG1) to IgG2a, IgG2b and IgG3. Although both protocols of SEB treatment did not lead to a major deletion of the Vβ8 T cell population, they did reduce the proliferative response of Vβ8+ T cells to OVA. These data indicate that the bacterial toxin SEB is capable of modifying the immediate hypersensitivity response induced by OVA by altering the functional capacity of antigen-reactive Vβ8 T cells. 相似文献
107.
Coby C Larsen Faina Kligman Kandice Kottke-Marchant Roger E Marchant 《Biomaterials》2006,27(28):4846-4855
We have synthesized and characterized a novel peptide fluorosurfactant polymer (PFSP) modification that facilitates the adhesion and growth of endothelial cells on expanded polytetrafluoroetheylene (ePTFE) vascular graft material. This PFSP consists of a poly(vinyl amine) (PVAm) backbone with integrin binding Arg-Gly-Asp (RGD) peptides and perfluorocarbon pendant branches for adsorption and stable adhesion to underlying ePTFE. Aqueous PFSP solution was used to modify the surface of fluorocarbon substrates. Following subconfluent seeding, endothelial cell (EC) adhesion and growth on PFSP was assessed by determining cell population at different time points. Spectroscopic results indicated successful synthesis of PFSP. PFSP modification of ePTFE reduced the receding water contact angle measurement from 120 degrees to 6 degrees , indicating successful surface modification. Quantification of cell population demonstrated reduced EC attachment efficiency but increased growth rate on RGD PFSP compared with fibronectin (FN). Actin staining revealed a well-developed cytoskeleton for ECs on RGD PFSP indicative of stable adhesion. Uptake of acetylated low-density lipoprotein and positive staining for VE-Cadherin confirm EC phenotype for adherent cells. Production of prostacyclin, a potent antiplatelet agent, was equivalent between ECs on FN and RGD PFSP surfaces. Our results indicate successful synthesis and surface modification with PFSP; this is a simple, quantitative, and effective approach to modifying ePTFE to encourage endothelial cell attachment, growth, and function. 相似文献
108.
An autoradiographic method combined with a rosette technique was used to assess the bactericidal activity of individual control and inflammatory peritoneal macrophages (PM phi) in the presence or absence of expression of Fc receptor for IgG (FcR). There was a lack of FcR reactivity in a certain percentage of both categories of PM phi exposed to E. coli X43, a bacterium which is readily phagocytosed in the presence of specific antibody. Both rosetting and non-rosetting PM phi were capable of phagocytosing E. coli X43, but inflammatory PM phi showed a marked reduction in their capacity to ingest these bacteria compared with control PM phi. Once ingested the E. coli X43 were killed equally well by non-rosetting and rosetting control and inflammatory PM phi. 相似文献
109.
L O Vejerslev J K Larsen I J Christensen N Tommerup 《Cancer Genetics and Cytogenetics》1987,27(2):225-228
The DNA content of single villous cell nuclei in 14 normal pregnancies and 21 androgenetic moles with a 46,XX karyotype was measured by flow cytometry. Six molar specimens showed a low mean DNA content close to that of normal villi, whereas, 15 specimens were characterized by a high mean DNA content due to a large fraction of nuclei in the triploid to tetraploid region. The latter group presumably corresponds to the previously described "type II" moles in which the DNA pattern resembled the pattern seen in invasive moles and choriocarcinoma. 相似文献
110.
Gold thioglucose (GTG) has been known to be an obesity causing agent for over 40 years. GTG works by affecting dendrites in the mouse ventromedial hypothalamus (VMH) producing a permanent VMH lesion and subsequent hyperphagia and obesity. We have investigated the effect of beta-thioglucose (BTG), a glucose antimetabolite, on GTG-induced lesions in the VMH of mice. Twenty-eight female CF-1 mice were used in this study. Seven micron sections were made of the mouse VMH, mounted on glass slides, and stained with hematoxylin and eosin. A previous report of BTG action on GTG-induced lesions has not supported a competitive inhibition between these two drugs. Our data demonstrate that at 1/2 hour, 6 hours, and 12 hours post BTG, BTG completely inhibited GTG-induced lesions in the VMH. 相似文献