全文获取类型
收费全文 | 132556篇 |
免费 | 9845篇 |
国内免费 | 225篇 |
专业分类
耳鼻咽喉 | 1205篇 |
儿科学 | 3688篇 |
妇产科学 | 2754篇 |
基础医学 | 20808篇 |
口腔科学 | 3418篇 |
临床医学 | 11280篇 |
内科学 | 26912篇 |
皮肤病学 | 2274篇 |
神经病学 | 12865篇 |
特种医学 | 5405篇 |
外国民族医学 | 16篇 |
外科学 | 16574篇 |
综合类 | 553篇 |
现状与发展 | 1篇 |
一般理论 | 108篇 |
预防医学 | 15067篇 |
眼科学 | 2075篇 |
药学 | 7966篇 |
中国医学 | 241篇 |
肿瘤学 | 9416篇 |
出版年
2023年 | 570篇 |
2022年 | 950篇 |
2021年 | 2098篇 |
2020年 | 1518篇 |
2019年 | 2203篇 |
2018年 | 2750篇 |
2017年 | 2346篇 |
2016年 | 2502篇 |
2015年 | 2833篇 |
2014年 | 3843篇 |
2013年 | 5106篇 |
2012年 | 7850篇 |
2011年 | 7908篇 |
2010年 | 4082篇 |
2009年 | 4303篇 |
2008年 | 6976篇 |
2007年 | 7172篇 |
2006年 | 6934篇 |
2005年 | 6576篇 |
2004年 | 5586篇 |
2003年 | 5307篇 |
2002年 | 4829篇 |
2001年 | 4597篇 |
2000年 | 4597篇 |
1999年 | 4099篇 |
1998年 | 1680篇 |
1997年 | 1393篇 |
1996年 | 1459篇 |
1995年 | 1200篇 |
1994年 | 1113篇 |
1993年 | 1012篇 |
1992年 | 2784篇 |
1991年 | 2515篇 |
1990年 | 2399篇 |
1989年 | 2231篇 |
1988年 | 2039篇 |
1987年 | 1794篇 |
1986年 | 1712篇 |
1985年 | 1637篇 |
1984年 | 1167篇 |
1983年 | 1011篇 |
1982年 | 542篇 |
1981年 | 479篇 |
1980年 | 410篇 |
1979年 | 887篇 |
1978年 | 539篇 |
1977年 | 443篇 |
1974年 | 448篇 |
1973年 | 435篇 |
1972年 | 390篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
A J van Deventer H J van Vliet W C Hop W H Goessens 《Journal of clinical microbiology》1994,32(1):17-23
An immunodominant antigen with enolase enzyme activity was purified and used for the development of an assay to detect antibodies directed against this antigen in sera from patients with either invasive candidiasis or Candida colonization. The Au enzyme-linked immunosorbent assay established with the Candida enolase antigen was able to discriminate significantly between invasive candidiasis and colonization in both immunocompetent and immunodeficient groups of patients. The test had a sensitivity of 50% and a specificity of 86% in the immunocompetent patient group. In the immunodeficient patient group, a sensitivity of 53% and a specificity of 78% were established. Antibody levels determined by a counterimmunoelectrophoresis assay with the same set of sera resulted in a better sensitivity for sera from the immunocompetent patient group but a lower specificity, i.e., 80 and 29%, respectively. The counterimmunoelectrophoresis assay of sera from the immunodeficient patient group was not able to discriminate significantly between invasive candidiasis and colonization. With the use of more serum from each patient, the sensitivity of the antibody detection assays increased, while the specificity was maintained. The increase, however, was not statistically significant. Combining the results of the antibody assays with antigen titers obtained by the Cand-Tec assay did not improve the predictive value with respect to invasive candidiasis, as determined by multivariance regression analysis. Furthermore, it was demonstrated by performance of Western blots (immunoblots) that sera from patients as well as a rabbit antiserum cross-reacted with the Candida enolase and baker's yeast enolase enzyme. However, by tandem crossed immunoelectrophoresis it was demonstrated that the antibodies were directed toward different epitopes of the antigen. 相似文献
992.
Cationic immune complex arthritis in mice--a new model. Synergistic effect of complement and interleukin-1.
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
P. L. van Lent L. A. van den Bersselaar A. E. van den Hoek A. A. van de Loo W. B. van den Berg 《The American journal of pathology》1992,140(6):1451-1461
A novel cationic immune-complex-mediated arthritis (ICA) model was developed in mice. The highly cationic protein lysozyme was coupled to poly-L-lysine (PLL) and injected intra-articularly into the knee joint of the mouse, shortly after systemic administration of specific antibodies. A vehement joint inflammation developed, characterized by severe joint swelling and the influx of predominantly polymorphonuclear (PMN) leukocyte. Unique properties were combined in this protein. First, an excellent retention of the antigen in joint structures was found, facilitating sufficient IC formation in the synovial tissue and at the cartilage surface. Secondly, PLL.lysozyme appeared to be a potent inducer of interleukin-1 (IL-1). Similar IL-1 production was measured at 6 hours, in both immune or nonimmune mice. Neutralization with antibodies against either IL-1 alpha or IL-1 beta revealed that IL-1 alpha was the dominant cytokine. Resident cells were responsible for this IL-1 production since a comparable IL-1 signal was measured after intra-articular injection of PLL.lys in neutropenic mice. We further investigated whether IL-1 and complement factors were involved in the onset of this ICA. Neutralizing the IL-1 production with antibodies directed against IL-1 alpha and beta showed a significant decrease in joint swelling. Complement depletion by cobra venom factor also prevented the onset of arthritis for the greater part. Only a minor swelling remained at 6 hours after eliciting arthritis, which was similar to the swelling after injecting the antigen alone and probably reflects IL-1 mediated inflammation. In this study, the authors show a synergistic action of IL-1 and complement in the onset of cationic ICA. Unique properties of the antigen such as excellent retention and its ability to induce IL-1 are combined within one molecule and make this antigen arthritogenic in the presence of antibodies and complement activation. 相似文献
993.
Molecular test for the detection of tumor cells in blood and sentinel nodes of melanoma patients. 总被引:2,自引:0,他引:2
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
994.
Immunogenic properties of octasaccharide-protein conjugates derived from Klebsiella serotype 11 capsular polysaccharide.
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
J W Zigterman J E van Dam H Snippe F T Rotteveel M Jansze J M Willers J P Kamerling J F Vliegenthart 《Infection and immunity》1985,47(2):421-428
The tetrasaccharide repeating unit of the capsular polysaccharide of Klebsiella serotype 11, K11PS, comprises the following sequence: [----3)-beta-D-GlcpA-(1----3)-alpha-D-Galp-(1----3)-beta-D-Glcp-(1 ----] with a 4,6-O-(1-carboxyethylidene)-alpha-D-galactopyranosyl residue linked to O-4 of the glucuronic acid residue. Octasaccharide (OS) derived from K11PS by bacteriophage phi 11-associated glycanase, was coupled to bovine serum albumin and to keyhole limpet hemocyanin. The immunogenicity of various antigens after intraperitoneal immunization was studied by measuring the levels of circulating antibodies. Injection of BALB/c mice with K11PS resulted in induction of 2-mercaptoethanol-sensitive immunoglobulin M antibodies. The responses observed in BALB/c nu/nu mice and in male (CBA/N X C3H/HeN)F1 mice indicate that K11PS is a thymus-independent type 2 antigen. Immunization of BALB/c mice with either OS-bovine serum albumin or OS-keyhole limpet hemocyanin resulted in the induction of circulating 2-mercaptoethanol-resistant immunoglobulin G antibodies. Results in BALB/c nu/nu mice indicate that the OS-protein conjugates are thymus-dependent antigens. Since the OS-keyhole limpet hemocyanin conjugate induced antibodies in both (CBA/N X C3H/HeN)F1 females and males, we propose to refer to this kind of antigen as a thymus-dependent type 1 antigen, whereas OS-bovine serum albumin, which evoked immunoglobulins in (CBA/N X C3H/HeN)F1 females only, can be referred to as a thymus-dependent type 2 antigen. 相似文献
995.
P Faaber P J Capel G P Rijke G Vierwinden L B van de Putte R A Koene 《Clinical and experimental immunology》1984,55(3):502-508
Ten sera of patients with systemic lupus erythematosus (SLE) were tested in an enzyme linked immunosorbent assay for their ability to react with glycosaminoglycans, constituents of proteoglycans, in relation to their anti-DNA reactivity. The SLE sera reacted with hyaluronic acid and chondroitin sulphate and this reactivity correlated with the anti-DNA activity of these sera. By contrast, sera obtained from patients with other autoimmune diseases or normal sera lacked any of these reactivities. Anti-DNA antibodies purified by affinity chromatography with either oligo dT cellulose or Cibracon blue F3Ga Sepharose reacted with DNA as well as with hyaluronic acid. The cross-reactivity of anti-DNA antibodies could be confirmed by the reaction of a mouse monoclonal anti-DNA antibody with DNA, hyaluronic acid, and chondroitin sulphate. This pattern of cross-reactivities of anti-DNA antibodies suggests that several compounds can function as antigenic targets for these antibodies provided that their structures contain repeating negatively charged groups. 相似文献
996.
Purification of specific precipitinogen and extraction of endotoxin from Haemophilus influenzae.
下载免费PDF全文
![点击此处可从《Journal of clinical pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
J C van der Zwan J Dankert K de Vries N G Orie H F Kauffman 《Journal of clinical pathology》1978,31(4):370-377
After purifying a Haemophilus influenzae precipitinogen from endotoxic activity by means of ultracentrifugation, column chromatography (Sepharose 6B) and ion exchange chromatography (DEAE Sephadex A25) a fraction was obtained which still contained a specific precipitinogen that was virtually free of endotoxin. Furthermore, during the chromatographic procedures fractions with a high and a low molecular weight endotoxic activity were found. The limulus lysate test was more sensitive in the high molecular weight fractions and the LD50 in mice in the low molecular weight fractions with endotoxic activity. 相似文献
997.
Dientamoeba fragilis is a globally occurring parasite that has been recognized as a causative agent of gastrointestinal symptoms. A single-round PCR was developed to detect D. fragilis DNA directly from human stool samples. The genetic diversity of D. fragilis from 93 patients and 6 asymptomatic carriers was examined by PCR followed by restriction fragment length polymorphism and sequencing of part of the small-subunit rRNA gene. The data show that D. fragilis sequences can be studied directly from fecal specimens despite the absence of a cyst stage and without the need for prior culturing. In addition, the results suggest strongly that D. fragilis shows remarkably little variation in its small-subunit rRNA gene. 相似文献
998.
Functional activity of antibodies against the recombinant OpaJ protein from Neisseria meningitidis
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
de Jonge MI Vidarsson G van Dijken HH Hoogerhout P van Alphen L Dankert J van der Ley P 《Infection and immunity》2003,71(5):2331-2340
The opacity proteins belong to the major outer membrane proteins of the pathogenic Neisseria and are involved in adhesion and invasion. We studied the functional activity of antibodies raised against the OpaJ protein from strain H44/76. Recombinant OpaJ protein was obtained from Escherichia coli in two different ways: cytoplasmic expression in the form of inclusion bodies followed by purification and refolding and cell surface expression followed by isolation of outer membrane complexes (OMCs). Immunization with purified protein and Quillaja saponin A (QuilA) induced high levels of Opa-specific antibodies, whereas the E. coli OMC preparations generally induced lower levels of antibodies. Two chimeric Opa proteins, hybrids between OpaB and OpaJ, were generated to demonstrate that the hypervariable region 2 is immunodominant. Denatured OpaJ with QuilA induced high levels of immunoglobulin G2a (IgG2a) in addition to IgG1, whereas refolded OpaJ with QuilA induced IgG1 exclusively. These sera did not induce significant complement-mediated killing. However, all sera blocked the interaction of OpaJ-expressing bacteria to CEACAM1-transfected cells. In addition, cross-reactive blocking of OpaB-expressing bacteria to both CEACAM1- and CEA-transfected cells was found for all sera. Sera raised against purified OpaJ and against OpaJ-containing meningococcal OMCs also blocked the nonopsonic interaction of Opa-expressing meningococci with human polymorphonuclear leukocytes. 相似文献
999.
Characterization of gene expression profiles associated with glioma progression using oligonucleotide-based microarray analysis and real-time reverse transcription-polymerase chain reaction 总被引:23,自引:0,他引:23
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
1000.
Applicability of a real-time quantitative PCR assay for diagnosis of respiratory syncytial virus infection in immunocompromised adults 总被引:5,自引:0,他引:5
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
van Elden LJ van Loon AM van der Beek A Hendriksen KA Hoepelman AI van Kraaij MG Schipper P Nijhuis M 《Journal of clinical microbiology》2003,41(9):4378-4381
Respiratory syncytial virus (RSV) accounts for the majority of respiratory virus infections, producing high mortality rates in immunocompromised patients with hematologic malignancies. The available methods for the rapid detection of RSV by antigen detection or PCR either lack sensitivity, require complex laboratory manipulation, or have not been evaluated in this patient population. To assess the applicability of a TaqMan-based real-time PCR technique for the detection of RSV A and B in immunocompromised adults, we developed a rapid, sensitive detection method that simultaneously detects RSV A and B and can be applied in routine diagnostics. The specificity of the assay was assessed using a panel of reference strains of other respiratory viruses and RSV. Electron microscopy-counted stocks of RSV A and B were used to develop a quantitative PCR format. Eleven copies of viral RNA could be detected for RSV A strain Long, and 14 copies could be detected for RSV B strain 9320, corresponding to 50% tissue culture infective doses of 0.86 and 0.34, respectively. The assay was evaluated on 411 combined nose and throat swabs derived from immunocompromised adults with or without signs of respiratory tract infection. The diagnostic efficacy of the TaqMan PCR determined on the clinical samples showed that this real-time PCR technique was substantially more sensitive than the combination of conventional viral culture and shell vial culture. None of the clinical specimens derived from patients without signs of respiratory illness were found to be positive for RSV by real-time TaqMan PCR. 相似文献