全文获取类型
收费全文 | 9915篇 |
免费 | 464篇 |
国内免费 | 39篇 |
专业分类
耳鼻咽喉 | 115篇 |
儿科学 | 437篇 |
妇产科学 | 121篇 |
基础医学 | 1215篇 |
口腔科学 | 197篇 |
临床医学 | 788篇 |
内科学 | 2081篇 |
皮肤病学 | 287篇 |
神经病学 | 760篇 |
特种医学 | 330篇 |
外科学 | 1501篇 |
综合类 | 177篇 |
一般理论 | 1篇 |
预防医学 | 607篇 |
眼科学 | 336篇 |
药学 | 894篇 |
中国医学 | 46篇 |
肿瘤学 | 525篇 |
出版年
2023年 | 77篇 |
2022年 | 196篇 |
2021年 | 376篇 |
2020年 | 208篇 |
2019年 | 243篇 |
2018年 | 296篇 |
2017年 | 202篇 |
2016年 | 292篇 |
2015年 | 321篇 |
2014年 | 434篇 |
2013年 | 533篇 |
2012年 | 791篇 |
2011年 | 793篇 |
2010年 | 441篇 |
2009年 | 361篇 |
2008年 | 554篇 |
2007年 | 551篇 |
2006年 | 490篇 |
2005年 | 460篇 |
2004年 | 446篇 |
2003年 | 405篇 |
2002年 | 369篇 |
2001年 | 161篇 |
2000年 | 145篇 |
1999年 | 117篇 |
1998年 | 72篇 |
1997年 | 72篇 |
1996年 | 71篇 |
1995年 | 49篇 |
1994年 | 35篇 |
1993年 | 34篇 |
1992年 | 65篇 |
1991年 | 51篇 |
1990年 | 55篇 |
1989年 | 66篇 |
1988年 | 58篇 |
1987年 | 54篇 |
1986年 | 43篇 |
1985年 | 55篇 |
1984年 | 56篇 |
1983年 | 38篇 |
1982年 | 32篇 |
1981年 | 24篇 |
1980年 | 27篇 |
1979年 | 37篇 |
1978年 | 18篇 |
1977年 | 23篇 |
1974年 | 11篇 |
1971年 | 11篇 |
1970年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
Roest RW Carman WF Maertzdorf J Scoular A Harvey J Kant M Van Der Meijden WI Verjans GM Osterhaus AD 《Journal of medical virology》2004,73(4):601-604
Clinical recurrences of Herpes simplex virus type 1 (HSV-1)-associated genital herpes are thought to be caused by reactivation of latent endogenous HSV-1. However, the possibility of reinfection with exogenous HSV-1 cannot be excluded. This study aimed to determine the incidence of genital HSV-1 superinfection in patients by investigating the genotype of sequential HSV-1 isolates obtained from the same anatomical site of patients with clinical recurrences of genital HSV-1 recurrent genital herpes. Sequential genital HSV-1 isolates were genotyped by PCR amplification of the hypervariable regions located within the HSV-1 genes US1 and US12. Whereas the sequential HSV-1 isolates in 11 of the 13 patients studied had the same genotypes, the sequential isolates of 2 patients showed a different genotype. The data suggest that HSV-1-induced recurrent genital herpes can be associated with genital reinfection with an exogenous HSV-1 strain. 相似文献
33.
Dunn GP Bruce AT Sheehan KC Shankaran V Uppaluri R Bui JD Diamond MS Koebel CM Arthur C White JM Schreiber RD 《Nature immunology》2005,6(7):722-729
'Cancer immunoediting' is a process wherein the immune system protects hosts against tumor development and facilitates outgrowth of tumors with reduced immunogenicity. Although interferon-gamma (IFN-gamma) is known to be involved in this process, the involvement of type I interferons (IFN-alpha/beta) has not been elucidated. We now show that, like IFN-gamma, endogenously produced IFN-alpha/beta was required for the prevention of the growth of primary carcinogen-induced and transplantable tumors. Although tumor cells are important IFN-gamma targets, they are not functionally relevant sites of the actions of the type I interferons. Instead, host hematopoietic cells are critical IFN-alpha/beta targets during development of protective antitumor responses. Therefore, type I interferons are important components of the cancer immunoediting process and function in a way that does not completely overlap the functions of IFN-gamma. 相似文献
34.
In vitro gene expression strategy was used for the production of polyclonal antiserum to the nucleocapsid protein (NP) of Groundnut bud necrosis virus (GBNV). The GBNV NP gene from cowpea isolate was cloned into 6x His-tagged UA cloning vector and expressed in Escherichia coli [M15] cells. The fusion protein was detected in insoluble fraction and was purified by using Ni-NTA agarose resin. The purified 6x His-fusion protein (32 kDa) was used for immunisation to produce a high titre polyclonal antiserum. The antiserum to the NP of GBNV at 1:4000 dilution detected successfully natural infection of GBNV and Watermelon bud necrosis virus in a wide range of cucurbitaceous, leguminous and solanaceous hosts from different locations. 相似文献
35.
B L Tekwani L M Tripathi S Mukerjee S Gupta V C Pandey J C Katiyar S Ghatak O P Shukla 《Experimental and molecular pathology》1990,52(3):330-339
Experimental infection of golden hamsters with the hookworm, Ancylostoma ceylanicum, caused a profound decline in the hepatic microsomal cytochrome P450 content. Concomitant decrease was also noticed in aminopyrine N-demethylase and benzo[a]pyrene hydroxylase activities. However, aniline hydroxylase activity was only marginally elevated during the infection. Microsomal markers, viz., cytochrome b5, NADH-cytochrome-c reductase, and glucose-6-phosphatase, were not significantly altered. Hepatic tissue exhibited an accumulation of lipids, especially phospholipids, triglycerides, and cholesterol, resulting in fatty necrosis around the central vein region. Isolated hepatic microsomes showed a decrease in phosphatidylcholine content. Impairment in hepatic mixed function oxidase (MFO) activities was further confirmed by prolongation in hexobarbital sleeping time and zoxazolamine-induced paralysis. The hepatic MFO system of A. ceylanicum-infected hamsters responded qualitatively and quantitatively in a manner similar to that of control hamsters, upon stimulation with selective chemical inducers like phenobarbitone and 3-methylcholanthrene. Kinetic and in vitro substrate binding studies revealed that for aminopyrine the substrate affinity and the maximum enzyme activity (Vmax) were decreased, while for aniline the binding affinity was decreased and the binding capacity was enhanced. Results indicate specific/selective impairment of the hepatic microsomal cytochrome P450 system during hookworm infection and may have many practical implications in toxicology and pharmacology. 相似文献
36.
Hunter S Weiss S Ou CY Jaye D Young A Wilcox J Arbiser JL Monson D Goldblum J Nolen JD Varma V 《Human pathology》2005,36(9):987-993
Apolipoprotein D (apoD) expression was studied in nonneoplastic peripheral nerve, neurofibromas (NFs), and malignant peripheral nerve sheath tumors (MPNSTs) by quantitative polymerase chain reaction, in situ hybridization, and immunohistochemistry. Multiplex quantitative polymerase chain reaction for messenger RNA was performed on a series of formalin-fixed and paraffin-embedded specimens that included 9 MPNSTs, 12 NFs, and 4 normal peripheral nerves. The average apoD expression was 108-fold decreased (DeltaCt = -7.3) in the MPNSTs compared with the NFs (P < .05). ApoD expression levels were 3.0-fold elevated (DeltaCt = 1.7) in the NFs compared with nonneoplastic peripheral nerve (P < .05). In situ hybridization for apoD RNA was performed on a separate series of 10 cases in which each microscopic section included both MPNST and the NF from which it arose. These studies confirmed elevated apoD expression in NFs compared with MPNSTs and demonstrated that this expression was variable among individual cells within the NFs. Differential expression by immunohistochemistry could only be demonstrated in selected areas, most likely because apoD protein is a small molecule that is secreted out of the cell into the extracellular space and plasma. ApoD expression initially increases a small amount with the formation of NFs from nonneoplastic peripheral nerve and subsequently decreases markedly as NFs transform into MPNSTs. This expression pattern may serve as a marker for cell cycle inhibition during peripheral nerve tumorigenesis. 相似文献
37.
Vegetarians may have subtle nutritional deficiencies which have been related to the occurrence of an unrecognized malabsorption syndrome. The excess phytate content in cereals, nuts, legumes and oilseeds which represent the mainstay of their food intake, seems to play a central role in the pathogenesis of this malabsorption syndrome as an inverse relationship has been shown to link the phytate content of the diet with the intestinal absorption of trace minerals and proteins. We postulate that manipulating the endogenous digestive microflora of subjects on a vegetarian diet through administering probiotic lactic bacteria would represent an innovative tool to counteract the occurrence of the malabsorption syndrome dependent on the high phytate content of their diet. Even though there are no data about the composition of endogenous digestive microflora in subjects on a vegetarian diet, we expect that probiotic lactobacilli can interact with or affect distinct yet interrelated components within the intestinal milieu, such as epithelial cells, enteric flora, and/or mucosal immune cells. This would ultimately translate into the correction of the unregulated mechanisms implicated in the altered intestinal absorption of trace metals and proteins commonly seen in vegetarians. Clinical experience with probiotic therapy of patients with inflammatory bowel disease fully agrees with this view. One additional point of interest is that probiotic lactobacilli, and other species of the endogenous digestive microflora as well, are an important source of the enzyme phytase which catalyses the release of phosphate from phytate and hydrolyses the complexes formed by phytate and metal ions or other cations, rendering them more soluble ultimately improving and facilitating their intestinal absorption. The regular intake of probiotic preparation, may represent a cheap and safe tool in order to convert a diet with a low potential for bioavailability of trace minerals and proteins, such as the vegetarian diet, into a diet with a high bioavailability potential. The benefit of such an approach would not be restricted to vegetarians. 相似文献
38.
Jhingan HP Jain R Desai NG Vaswani M Tripathi BM Pandey RM 《Indian journal of medical sciences》2002,56(10):495-500
Self-report validity of recent drug use among heroin abusers depends on many factors including the population being studied and the setting in which the study is carried out. This study was conducted by the treating physicians to assess the self-report validity of recent heroin use by heroin dependent patients in the outdoor setting using 'thin layer chromatography' (TLC) and two highly sensitive methods of urinalysis viz. 'gas liquid chromatography' (GLC) and 'high performance liquid chromatography' (HPLC). Out of seventy-six heroin dependent patients who entered the study, 64 provided urine sample on the same day. Patients' self-report about recent opiate use was found to have a moderate agreement with urinalysis report. However, it is important to validate it with urinalysis during the treatment process because a substantial proportion of patients fails to report recent opiate use. It is recommended that all drug dependence treatment centres should be equipped with a sensitive urinalysis facility. Otherwise, the outcome of the treatment process should be considered with caution. 相似文献
39.
Illes Z Stern JN Keskin DB Reddy J Brosnan CF Waldner H Santambrogio L Kuchroo VK Strominger JL 《European journal of immunology》2005,35(12):3683-3693
The random amino acid copolymers FYAK and VWAK ameliorate EAE in a humanized mouse model expressing both a human transgenic myelin basic protein (MBP)85-99-specific T cell receptor and HLA-DR2. Here we show that microglia isolated from the central nervous system (CNS) of humanized mice with EAE induced by MBP85-99 and treated with these copolymers had reduced expression of HLA-DR, and thus reduced capacity to present MBP85-99 and activate transgenic T cells. In vitro microglia up-regulated empty HLA-DR2 upon activation with GM-CSF with or without LPS or IFN-gamma, but not with IL-4 or IL-10. Correspondingly, gene chip arrays showed that the CNS of untreated and YFAK-treated mice differentially expressed pro- and anti-inflammatory molecules during MBP85-99-induced EAE. Interestingly, microglia expressed the full-length gammabeta and alphabeta subunits of the tetrameric adaptor protein complexes AP-1 and AP-2 respectively, but after treatment with GM-CSF these complexes were cleaved, as had been found in immature dendritic cells derived from bone marrow. Strikingly, in vivo the perivascular lymphocyte infiltration seen in untreated mice immunized with MBP85-99 was composed of equal numbers of hVbeta2+ MPB85-99-specific transgenic and hVbeta2- endogenous T cells, while the much smaller infiltration seen after treatment with YFAK was composed predominantly of hVbeta2- endogenous T cells. 相似文献
40.
H Hy?ty J P Pandey M Lehtinen P Kulomaa P Leinikki 《Experimental and clinical immunogenetics》1988,5(1):52-59
We have found elevated IgA class mumps and Coxsackie B4 virus antibodies and IgA/IgG antibody ratios in type 1 diabetic patients. However, IgA class herpes simplex (HSV1) virus antibodies showed no difference between patients and controls. To study the possible contribution of genetically polymorphic immunoglobulin markers to the pronounced IgA class reactivity Ig allotypes (Gm, A2m and Km determinants) were compared to virus antibodies in diabetic patients and healthy controls. Ig allotypes were equally distributed in both groups suggesting that the genes coding for these structures are not in close linkage disequilibrium with susceptibility gene(s) for type 1 diabetes. Accordingly, pronounced IgA class immune response in diabetic patients is hardly due to Ig allotype related factors. Patients had elevated IgA class mumps and Coxsackie B4 antibodies and IgA/IgG antibody ratios independently of the Gm phenotype group. In healthy subjects but not in diabetic patients IgA class mumps antibody levels and IgA/IgG mumps antibody ratios significantly correlated with the Gm phenotypes. Such Gm association was not observed in Coxsackie B4 or HSV1 antibodies. These results suggest that though Gm phenotypes have a general effect on mumps specific antibody response, some other factors than Ig allotypes are responsible for the elevated IgA class mumps and Coxsackie B antibody levels and IgA/IgG antibody ratios in type 1 diabetes. 相似文献