全文获取类型
收费全文 | 7523篇 |
免费 | 486篇 |
国内免费 | 50篇 |
专业分类
耳鼻咽喉 | 52篇 |
儿科学 | 110篇 |
妇产科学 | 147篇 |
基础医学 | 1053篇 |
口腔科学 | 322篇 |
临床医学 | 737篇 |
内科学 | 1693篇 |
皮肤病学 | 154篇 |
神经病学 | 668篇 |
特种医学 | 237篇 |
外科学 | 1147篇 |
综合类 | 50篇 |
一般理论 | 4篇 |
预防医学 | 411篇 |
眼科学 | 161篇 |
药学 | 664篇 |
中国医学 | 19篇 |
肿瘤学 | 430篇 |
出版年
2023年 | 53篇 |
2022年 | 89篇 |
2021年 | 175篇 |
2020年 | 117篇 |
2019年 | 160篇 |
2018年 | 154篇 |
2017年 | 167篇 |
2016年 | 176篇 |
2015年 | 202篇 |
2014年 | 288篇 |
2013年 | 290篇 |
2012年 | 507篇 |
2011年 | 522篇 |
2010年 | 277篇 |
2009年 | 268篇 |
2008年 | 475篇 |
2007年 | 463篇 |
2006年 | 460篇 |
2005年 | 464篇 |
2004年 | 402篇 |
2003年 | 404篇 |
2002年 | 360篇 |
2001年 | 95篇 |
2000年 | 67篇 |
1999年 | 72篇 |
1998年 | 94篇 |
1997年 | 77篇 |
1996年 | 71篇 |
1995年 | 55篇 |
1994年 | 50篇 |
1993年 | 35篇 |
1992年 | 44篇 |
1991年 | 50篇 |
1990年 | 40篇 |
1989年 | 49篇 |
1988年 | 37篇 |
1987年 | 39篇 |
1986年 | 30篇 |
1985年 | 30篇 |
1984年 | 32篇 |
1983年 | 34篇 |
1982年 | 30篇 |
1981年 | 28篇 |
1979年 | 16篇 |
1968年 | 14篇 |
1967年 | 15篇 |
1934年 | 16篇 |
1933年 | 20篇 |
1932年 | 18篇 |
1931年 | 14篇 |
排序方式: 共有8059条查询结果,搜索用时 15 毫秒
71.
Ghiorzo P Villaggio B Sementa AR Hansson J Platz A Nicoló G Spina B Canepa M Palmer JM Hayward NK Bianchi-Scarrà G 《Human pathology》2004,35(1):25-33
Little is known about the correlation between the loss of p16 expression and tumor progression in familial melanoma; no systematic study has been conducted on p16 expression in melanocytic tumors from patients carrying germline CDKN2A mutations. We analyzed 98 early primary lesions from familial patients, previously tested for germline CDKN2A status, by quantitative immunohistochemistry using 3 p16 antibodies. We found that p16 expression was inversely correlated with tumor progression and was significantly lower in melanomas, including in situ lesions, than in nevi. Of other features analyzed, tumor thickness showed the most significant correlation with p16 levels. Lesions from mutation-negative patients displayed combined nuclear and cytoplasmic staining. However, some mutation-positive lesions (ie, G101W, 113insR, M53I, R24P, and 33ins24), including benign nevi, showed nuclear mislocalization, confirming previous studies suggesting that subcellular distribution indicates functional impairment of p16. 相似文献
72.
Sainova IV Kril AI Simeonov KB Popova TP Ivanov IG 《Journal of virological methods》2005,124(1-2):37-40
The ability for replication of vaccine avian pox viral strains FK and Dessau in cell clones, derived from the EBTr cell line, derived from embryonic bovine trachea, was studied. The derived seven cell clones showed different morphological characteristics and diverse sensitivity to both vaccine avian pox viral strains. Hence, the EBTr-derived cell clones could be used for cultivation, as well as for differentiation of vaccine avian pox viral strains. In addition, studies have been undertaken to elucidate the possible use of cultivated strains in these heterologous cell culture system's vaccine avian pox viral strains for biotechnology, as well as for solving problems, related to infection of people with avian viruses. 相似文献
73.
The deprivation effect (DE)--an increase in the level of free-choice consumption of alcohol after a period of forced abstinence--may reflect relapselike drinking and be relevant for modeling alcohol abuse. However, the behavioral mechanisms of the DE are unclear. In these experiments, rats had unlimited free-choice access to water and saccharin-containing solutions and underwent repeated episodes of saccharin deprivation. It was found that DE magnitude correlates positively with the deprivation phase duration, expression of the DE is highly context dependent, and the DE can be prevented by extinguishing response to the saccharin-associated stimuli. Thus, DE procedures may be useful for studying the effects of continued exposure to stimuli associated with various primary reinforcers such as drugs of abuse. 相似文献
74.
The expression of CD45R on mouse T cells has been studied. This antigen is expressed on the two higher molecular weight bands of CD45 (or T200) and in mouse it is currently used as a marker of B cells (B220). Here we confirm that CD45R is expressed on some mouse T cell clones. We show that a small but measurable proportion of mouse spleen and peripheral blood lymphocyte T cells gives positive immunofluorescence with B220. Also CD45R-specific antibodies increase the proliferation response to phytohemagglutinin up to 3-fold, thus confirming that CD45R molecules transduce a signal into mouse T cells. 相似文献
75.
Riedl M Czech T Slootweg J Czernin S Hainfellner JA Schima W Vierhapper H Luger A 《Endocrine pathology》1995,6(2):159-166
This report describes a case of lymphocytic hypophysitis in a 63-year-old man who presented with symptoms of a pituitary mass
lesion associated with hypothyroidism and hypogonadism. Postoperative endocrinological testing demonstrated gonadotropic,
thyrotropic, and corticotropic hypopituitarism, and the patient was commenced on replacement therapy with hydrocortisone and
levothyroxine. Histological examination of the pituitary tissue obtained by transsphenoidal surgery revealed lymphocytic hypophysitis
without evidence of a pituitary adenoma. The vast majority of patients with lymphocytic hypophysitis are women particularly
during pregnancy and the puerperium. Until recently only four men were reported in the literature. The pathogenesis of lymphocytic
hypophysitis is uncertain but autoimmune mechanisms are possibly involved. 相似文献
76.
77.
Hänfler J Kreuzer KA Laurisch K Rayes N Neuhaus P Schmidt CA Oettle H 《Medical microbiology and immunology》2003,192(4):197-204
Even now rare human cytomegalovirus (hCMV) reactivation is still a life-threatening complication after solid organ transplantation. Although PCR techniques are regarded as the most sensitive detection methods for hCMV, their accuracy and reproducibility are limited. This is a major disadvantage with quantitative PCR assays, which are thought to provide valuable information about hCMV latency or active viral replication in transplant patients. To enhance the diagnostic safety of quantitative hCMV PCR, we developed a duplex real-time fluorescence PCR that is capable of quantifying hCMV DNA and beta-actin DNA as internal control simultaneously within one reaction. By the use of 6-carboxyfluorescein and hexa-chloro-6-carboxyfluorescein as reporter fluorophores and 4-(4'-dimethylamino-phenylazo) benzoic acid as dark quencher dye, hCMV DNA and beta-actin DNA could be quantified in parallel in a wide linear range from 10(1) to 10(7) copies, each. To test the clinical applicability of this approach, we investigated hCMV DNA kinetics in peripheral leukocytes of three hCMV antigen-positive and four antigen-negative patients after liver transplantation, as assessed by intracellular hCMV pp65 alkaline phosphate-anti-alkaline phosphate (APAAP) complex. While all APAAP-negative individuals remained PCR negative, kinetics of HCMV DNA in leukocyte DNA samples of APAAP-positive patients correlated closely with hCMV antigen tests. Here, comparison of separate and simultaneous target quantitation revealed identical results. It is of interest that, while single hCMV antigen positivity is commonly not regarded as a reliable parameter of viral reactivation, in our study a viral load greater than 10(4) copies/2x10(5) beta-actin DNA copies clearly indicated a subsequent increase in APAAP-positive leukocytes. We conclude that with the presented method the reliability of hCMV quantitation via real-time PCR can be substantially increased and may be used to monitor hCMV kinetics in vivo. 相似文献
78.
Brink AA Wiegant JC Szuhai K Tanke HJ Kenter GG Fleuren GJ Schuuring E Raap AK 《Cancer Genetics and Cytogenetics》2002,134(2):145-150
Infection with high-risk type human papillomavirus (HPV) is a necessary causal factor in the pathogenesis of cervical carcinoma. In most invasive cervical cancers, HPV is integrated in the host cell genome, and additional genetic aberrations are observed among which are chromosomal aberrations. To analyze in detail such often complex chromosomal changes and simultaneously map HPV integration sites, we extended the multiplicity of the combined binary ratio labeling fluorescence in situ hybridization (COBRA-FISH) technique to 49 by inclusion of a large Stokes' shift fluorochrome as the third binary label. The technique allows mapping of the integrated HPV genome in the context of p- and q-arm COBRA-FISH, with a sensitivity of one copy of the HPV genome as tested for HPV 16 in SiHa cells. We investigated the molecular karyotypes and integration patterns of HPV types 16 and 18 in metaphase spreads from short-term cultures of primary cervical carcinomas (n=5). Of the tested cervical carcinomas, two contained integrated HPV at 8q24, one of which in addition harbored the integrated virus near a translocation breakpoint. Two carcinomas had integrated HPV at 17q21 through 23 in a morphologically normal chromosome 17. One carcinoma contained HPV at 1q42 in a morphologically normal chromosome 1. Our data illustrate the efficacy of 49-color COBRA-FISH to resolve complex karyotypes and simultaneously map specific sequences in metaphases obtained from short-term solid tumor cultures. 相似文献
79.
80.
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