全文获取类型
收费全文 | 63971篇 |
免费 | 6843篇 |
国内免费 | 4847篇 |
专业分类
耳鼻咽喉 | 502篇 |
儿科学 | 630篇 |
妇产科学 | 606篇 |
基础医学 | 7443篇 |
口腔科学 | 1228篇 |
临床医学 | 8588篇 |
内科学 | 10081篇 |
皮肤病学 | 618篇 |
神经病学 | 3603篇 |
特种医学 | 2273篇 |
外国民族医学 | 52篇 |
外科学 | 6575篇 |
综合类 | 11277篇 |
现状与发展 | 19篇 |
一般理论 | 5篇 |
预防医学 | 4445篇 |
眼科学 | 1911篇 |
药学 | 6942篇 |
41篇 | |
中国医学 | 3526篇 |
肿瘤学 | 5296篇 |
出版年
2024年 | 794篇 |
2023年 | 1206篇 |
2022年 | 2735篇 |
2021年 | 3445篇 |
2020年 | 2666篇 |
2019年 | 2276篇 |
2018年 | 2270篇 |
2017年 | 2122篇 |
2016年 | 2003篇 |
2015年 | 2986篇 |
2014年 | 3703篇 |
2013年 | 3170篇 |
2012年 | 4923篇 |
2011年 | 5301篇 |
2010年 | 3144篇 |
2009年 | 2426篇 |
2008年 | 3358篇 |
2007年 | 3224篇 |
2006年 | 3176篇 |
2005年 | 3126篇 |
2004年 | 2044篇 |
2003年 | 1985篇 |
2002年 | 1634篇 |
2001年 | 1394篇 |
2000年 | 1432篇 |
1999年 | 1638篇 |
1998年 | 999篇 |
1997年 | 967篇 |
1996年 | 699篇 |
1995年 | 644篇 |
1994年 | 645篇 |
1993年 | 395篇 |
1992年 | 564篇 |
1991年 | 426篇 |
1990年 | 389篇 |
1989年 | 326篇 |
1988年 | 317篇 |
1987年 | 256篇 |
1986年 | 221篇 |
1985年 | 181篇 |
1984年 | 98篇 |
1983年 | 60篇 |
1982年 | 45篇 |
1981年 | 41篇 |
1980年 | 19篇 |
1979年 | 42篇 |
1978年 | 15篇 |
1977年 | 14篇 |
1964年 | 7篇 |
1936年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Lina?Hu Vishwa?Deep?Dixit Valeria?de Mello-Coelho Dennis?D?TaubEmail author 《BMC immunology》2004,5(1):15
Background
The CXCL1 chemokines, macrophage inflammatory protein-2 (MIP-2) and cytokine-induced neutrophil chemoattractant (KC), have been shown to play a role in a number of pathophysiological disease states including endotoxin-induced inflammation and bacterial meningitis. While the expression of these chemokines has been identified in a variety of cell types in the mouse, little is known about their expression with murine B-lymphocytes. 相似文献72.
73.
Koch WH Sullivan PS Roberts C Francis K Downing R Mastro TD Nkengasong J Hu D Masciotra S Schable C Lal RB 《Journal of clinical microbiology》2001,39(3):1017-1020
Six Food and Drug Administration (FDA)-licensed human immunodeficiency virus type 1 (HIV-1) and HIV-1/2 immunoassays, including five enzyme immunoassays and one rapid test, were challenged with up to 250 serum samples collected from various global sites. The serum samples were from individuals known to be infected with variants of HIV-1 including group M subtypes A, B, B', C, D, E, F, and G and group O. All immunoassays detected the vast majority of samples tested. Three samples produced low signal over cutoff values in one or more tests: a clade B sample, an untypeable sample with a low antibody titer, and a group O sample. It is concluded that HIV-1 immunoassays used in the United States are capable of detecting most HIV-1 group M variants. 相似文献
74.
The hepatitis B virus (HBV) genome is known to contain four conserved and overlapped open reading frames (ORFs) encoding the viral core, polymerase (P), surface (S), and X proteins. Whether HBV encodes other proteins has long been a major interest in the field. Using (32)P-labeling of an introduced protein kinase A site attached to the N- or C-terminus of the HBV polymerase gene, a 43-kDa P-S fusion protein was detected in cell lysate, secreted virions, and 22-nm subviral particles. Immunobiochemical studies showed that the 43-kDa protein contains the epitopes of the N-terminus of polymerase and most parts of the surface proteins. This 43-kDa protein was shown to be a glycoprotein, similar to the surface protein. RT-PCR and sequence analyses identified a spliced mRNA which was derived from pregenomic RNA with a deletion of 454 nucleotides (nt) from nt 2447 to 2902. This splice event creates a P-S fusion ORF. This finding is consistent with the result obtained from an immunobiochemical study. Mutations at the splice donor or acceptor site on the HBV genome abrogated the production of the 43-kDa protein. These mutants had no effect on viral replication in transfected HuH-7 cells. However, this P-S fusion protein is able to substitute for the LS protein in virion maturation. On the basis of these results, we conclude that the 43-kDa protein is a polymerase-surface fusion protein encoded by a spliced RNA. Similar to the LS protein, the 43-kDa P-S fusion protein is a structural protein of HBV and might play a role in the HBV life cycle. 相似文献
75.
76.
K N Tsiquaye B Portmann G Tovey H Kessler S Hu X Z Lu A J Zuckerman J Craske R Williams 《Journal of medical virology》1983,11(3):179-189
There are reports in the literature that infection with hepatitis A virus in hepatitis B carriers can result in resolution of the carrier state. In an attempt to induce clearance of the carrier state of hepatitis B virus in two persistently infected chimpanzees, the chimpanzees were infused with documented non-A, non-B infectious material. Biochemical and histopathological evidence of hepatitis was accompanied by the unique abnormalities of endoplasmic reticulum associated with non-A, non-B hepatitis in the chimpanzees. Elevation of alanine aminotransferase was accompanied by fourfold reduction in one chimpanzee and sixfold reduction in the other in the plasma levels of HBV-associated DNA polymerase activity and simultaneously by twofold reduction in the concentration of hepatitis B surface antigen in both chimpanzees. A mediator may account for these changes in markers of hepatitis B virus infection, and this mechanism may also explain the occurrence of spontaneous regression in some persistently infected carriers. The significance of transient red cell anaemia in non-A, non-B hepatitis, which was observed in one of the chimpanzees, is yet to be established. 相似文献
77.
非悬滴开放式培养法在鸡胚背根节体外培养中的应用 总被引:1,自引:0,他引:1
本研究针对悬滴培养法在操作和应用上存在的问题和局限性,改用操作简便、适用范围广的非悬滴开放式培养法培养鸡胚背根节。将数个鸡胚背根节按一定间隔种植在内置生长基质盖玻片的35mm培养皿中,加人适量培养液,置于CO2。孵箱中进行培养。结果显示.从培养24h至60h各时期,培养皿中背根节生长状况均良好,神经突起明显增长,表明用非悬滴开放式培养法培养鸡胚背根节是可行且可靠的。 相似文献
78.
Karwautz A Rabe-Hesketh S Hu X Zhao J Sham P Collier DA Treasure JL 《Psychological medicine》2001,31(2):317-329
BACKGROUND: The aim of this pilot study was to examine which unique factors (genetic and environmental) increase the risk for developing anorexia nervosa by using a case-control design of discordant sister pairs. METHODS: Forty-five sister-pairs, one of whom had anorexia nervosa and the other did not, were recruited. Both sisters completed the Oxford Risk Factor Interview for Eating Disorders and measures for eating disorder traits, and sib-pair differences. Blood or cheek cell samples were taken for genetic analysis. Statistical power of the genetic analysis of discordant same-sex siblings was calculated using a specially written program, DISCORD. RESULTS: The sisters with anorexia nervosa differed from their healthy sisters in terms of personal vulnerability traits and exposure to high parental expectations and sexual abuse. Factors within the dieting risk domain did not differ. However, there was evidence of poor feeding in childhood. No difference in the distribution of genotypes or alleles of the DRD4, COMT, the 5HT2A and 5HT2C receptor genes was detected. These results are preliminary because our calculations indicate that there is insufficient power to detect the expected effect on risk with this sample size. CONCLUSIONS: A combination of intrinsic and extrinsic factors increases the risk of developing anorexia nervosa. It would, therefore, be informative to undertake a larger study to examine in more detail the unique genetic and environmental factors that are associated with various forms of eating disorders. 相似文献
79.
Sclerochoroidal calcification is an uncommon condition. Metabolic evaluation and clinical examination are important to exclude associated systemic conditions such as the Bartter and Gitelman syndromes. It has been suggested that the lesions seen in sclerochoroidal calcification are calcium pyrophosphate dihydrate crystals. This report describes the first documented case in the UK of sclerochoroidal calcification associated with Gitelman syndrome and calcium pyrophosphate dihydrate deposition. 相似文献
80.
Identification of testis development and spermatogenesis-related genes in human and mouse testes using cDNA arrays 总被引:12,自引:0,他引:12
Sha J Zhou Z Li J Yin L Yang H Hu G Luo M Chan HC Zhou K;Spermatogenesis study group 《Molecular human reproduction》2002,8(6):511-517
We have constructed cDNA microarrays from the human testis large insert cDNA library, containing 9216 genes, together with several housekeeping genes. The cDNA microarrays were used to identify gene expression differences between human fetal and adult testes. Of >8700 hybridized clones, 731 exhibited significant differential expression characteristics. About 7500 genes were identified when the same cDNA microarrays were used for hybridization with cDNA probes from mouse testis, with 256 genes having significant differential expression between the age of 1-4 weeks. Among these genes, 101 were identified as critically related to testis development and possibly to spermatogenesis since they were found in both human and mouse testes, and expressed differentially at different stages of testis development. Of the 101 development-related genes, 59 full-length cDNAs have been sequenced previously, while the full-length cDNAs of the other 42 genes have not been published. We have obtained 11 full-length sequences of the 42 genes and deposited them in the GenBank. The conserved testis development-related genes found in both human and mouse testes may include genes that are likely to be involved in testicular functions, especially spermatogenesis, thus providing a basis for further functional characterization of the genes in mouse models. 相似文献