全文获取类型
收费全文 | 12466篇 |
免费 | 738篇 |
国内免费 | 39篇 |
专业分类
耳鼻咽喉 | 74篇 |
儿科学 | 393篇 |
妇产科学 | 205篇 |
基础医学 | 2258篇 |
口腔科学 | 273篇 |
临床医学 | 1023篇 |
内科学 | 2685篇 |
皮肤病学 | 337篇 |
神经病学 | 1372篇 |
特种医学 | 422篇 |
外国民族医学 | 3篇 |
外科学 | 1272篇 |
综合类 | 47篇 |
一般理论 | 6篇 |
预防医学 | 743篇 |
眼科学 | 241篇 |
药学 | 735篇 |
中国医学 | 19篇 |
肿瘤学 | 1135篇 |
出版年
2023年 | 79篇 |
2022年 | 152篇 |
2021年 | 286篇 |
2020年 | 207篇 |
2019年 | 302篇 |
2018年 | 348篇 |
2017年 | 216篇 |
2016年 | 325篇 |
2015年 | 349篇 |
2014年 | 452篇 |
2013年 | 593篇 |
2012年 | 857篇 |
2011年 | 941篇 |
2010年 | 482篇 |
2009年 | 491篇 |
2008年 | 758篇 |
2007年 | 788篇 |
2006年 | 768篇 |
2005年 | 752篇 |
2004年 | 701篇 |
2003年 | 647篇 |
2002年 | 566篇 |
2001年 | 188篇 |
2000年 | 192篇 |
1999年 | 203篇 |
1998年 | 154篇 |
1997年 | 116篇 |
1996年 | 91篇 |
1995年 | 87篇 |
1994年 | 63篇 |
1993年 | 61篇 |
1992年 | 99篇 |
1991年 | 101篇 |
1990年 | 73篇 |
1989年 | 93篇 |
1988年 | 57篇 |
1987年 | 57篇 |
1986年 | 53篇 |
1985年 | 47篇 |
1984年 | 36篇 |
1983年 | 37篇 |
1981年 | 25篇 |
1979年 | 39篇 |
1978年 | 26篇 |
1977年 | 22篇 |
1975年 | 18篇 |
1974年 | 22篇 |
1973年 | 28篇 |
1972年 | 19篇 |
1969年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Panda S Kumar MS Lokabiraman S Jayashree K Satagopan MC Solomon S Rao UA Rangaiyan G Flessenkaemper S Grosskurth H Gupte MD 《Journal of acquired immune deficiency syndromes (1999)》2005,39(1):9-15
OBJECTIVES: Determining HIV prevalence in injection drug users (IDUs) and their regular sex partners in Chennai, India. METHODS: A total of 226 IDUs and their regular sex partners were enrolled during April-July 2003. After informed consent was obtained, a semistructured questionnaire was administered and serum was tested for HIV antibody. RESULTS: The HIV seroprevalence was 30% (68/226) in IDUs and 5% in their regular sex partners (11/226). While in 25% of couples only the male partner was HIV positive, 5% of the couples were concordant for HIV infection and 70% were HIV negative. Fifty-seven percent of the HIV-positive IDUs and 45% of the HIV-infected women thought that they had "no chance" or "very little chance" of getting HIV, reflecting low HIV risk perception. More than 20% IDUs reported borrowing or lending of injection equipment. In univariate analyses "sex" and "condom use" with sex workers had no bearing but "more than twice a day injecting frequency," "history of incarceration," "tattoos," "recruitment from northern part of the city," and ever-injecting drugs in drug-selling places had significant association with HIV infection in IDUs. In an adjusted model, the odds of HIV infection were 2 times higher among IDUs who had ever injected drugs in drug-selling places and 6 times higher in those who were recruited from the northern part of central Chennai. CONCLUSION: Reducing sharing of injection equipment and unsafe tattooing through targeted and environmental interventions, increasing HIV risk perception, and promoting safer sex practices among IDUs and their sex partners are urgent program needs. 相似文献
72.
Christian Stock Birgit Gassner Christof R. Hauck Hannelore Arnold Sabine Mally Johannes A. Eble Peter Dieterich Albrecht Schwab 《The Journal of physiology》2005,567(1):225-238
Their glycolytic metabolism imposes an increased acid load upon tumour cells. The surplus protons are extruded by the Na+ /H+ exchanger (NHE) which causes an extracellular acidification. It is not yet known by what mechanism extracellular pH (pHe ) and NHE activity affect tumour cell migration and thus metastasis. We studied the impact of pHe and NHE activity on the motility of human melanoma (MV3) cells. Cells were seeded on/in collagen I matrices. Migration was monitored employing time lapse video microscopy and then quantified as the movement of the cell centre. Intracellular pH (pHi ) was measured fluorometrically. Cell–matrix interactions were tested in cell adhesion assays and by the displacement of microbeads inside a collagen matrix. Migration depended on the integrin α2β1. Cells reached their maximum motility at pHe ∼7.0. They hardly migrated at pHe 6.6 or 7.5, when NHE was inhibited, or when NHE activity was stimulated by loading cells with propionic acid. These procedures also caused characteristic changes in cell morphology and pHi . The changes in pHi , however, did not account for the changes in morphology and migratory behaviour. Migration and morphology more likely correlate with the strength of cell–matrix interactions. Adhesion was the strongest at pHe 6.6. It weakened at basic pHe , upon NHE inhibition, or upon blockage of the integrin α2β1. We propose that pHe and NHE activity affect migration of human melanoma cells by modulating cell–matrix interactions. Migration is hindered when the interaction is too strong (acidic pHe ) or too weak (alkaline pHe or NHE inhibition). 相似文献
73.
Krueger S Kalinski T Hundertmark T Wex T Küster D Peitz U Ebert M Nägler DK Kellner U Malfertheiner P Naumann M Röcken C Roessner A 《The Journal of pathology》2005,207(1):32-42
Recently, we identified increased cathepsin X expression in H. pylori-infected gastric mucosa. Here, we describe further up-regulation in gastric cancer and report on the role of inflammatory cytokines required for cathepsin X up-regulation in H. pylori-infected gastric mucosa, as well as on consequences for cellular invasion. Biopsy specimens were taken from the antrum, corpus and cardia of H. pylori-infected and non-infected patients. Gastric cancer samples were obtained from patients undergoing gastric surgery. Cathepsin X was detected in gastric mucosa by quantitative real-time RT-PCR, western blotting and immunohistochemistry. Induction of cathepsin X expression in epithelial and inflammatory cells caused by H. pylori infection was tested in in vitro contact and non-contact co-cultures of AGS cells and monocytic cells. Patients with H. pylori gastritis showed significantly higher cathepsin X mRNA (2.5-fold) and protein (1.6-fold) expression than H. pylori-negative patients. Cathepsin X was also up-regulated in gastric cancer (3-12-fold) compared to non-neoplastic mucosa. Cathepsin X was predominantly expressed by macrophages in the mucosal stroma and in glands of the antral mucosa. In addition, tumour cells stained for cathepsin X in 26 (68%) patients with gastric carcinoma. In general, staining was significantly more common (20 vs. 6 patients) and more intense (3.55 vs. 0.83) in intestinal type gastric cancer than in the diffuse type. In vitro cell culture experiments revealed that intercellular signalling between pathogenicity island (PAI)-positive H. pylori-infected epithelial cells and macrophages via soluble factors in the culture medium seems to be responsible for increased expression of cathepsin X in monocytes. Using antisense oligonucleotides, cathepsin X up-regulation was directly associated with higher invasiveness in vitro. Although no correlation of cathepsin X expression and TNM stage was found, our study demonstrates that cathepsin X plays a role not only in the chronic inflammation of gastric mucosa but also in the tumourigenesis of gastric cancer. 相似文献
74.
75.
Oliver Selberg Sabine Schlaak Hans J. Balks Alexander von zur Mühlen Manfred J. Müller 《European journal of applied physiology》1991,63(6):417-423
Summary The contribution of insulin (3.6 pmol sd kg body mass–1·min–1 to adrenaline-induced (0.164 nmol · kg fat free mass–1·min–1) thermogenesis was studied in ten postabsorptive healthy volunteers using two sequential protocols. Variables considered were oxygen consumption as well as carbon dioxide production, heart rate, blood pressure, plasma concentrations of glucose, insulin, glycerol, free fatty acids,-HO-butyrate and lactate. Adrenaline increased plasma concentrations of glucose, glycerol, free fatty acids, and-HO-butyrate, and heart rate and metabolic rate during normo-insulinaemia [61.3 (SEM 6.6) pmol·–1]. Similar effects were observed during hyperinsulinaemia [167.9 (SEM 18.7) pmol·–1], but the effect of adrenaline on oxygen consumption was reduced. On average, metabolic rate increased by 12.9% during normo-insulinaemia and by 8.9% during hyperinsulinaemia. We concluded that relative hyperinsulinaemia resulted in decreased adrenaline-induced thermogenesis and therefore increased whole body anabolism. 相似文献
76.
Gene expression patterns and gene copy number changes in dermatofibrosarcoma protuberans 总被引:5,自引:0,他引:5 下载免费PDF全文
Linn SC West RB Pollack JR Zhu S Hernandez-Boussard T Nielsen TO Rubin BP Patel R Goldblum JR Siegmund D Botstein D Brown PO Gilks CB van de Rijn M 《The American journal of pathology》2003,163(6):2383-2395
Dermatofibrosarcoma protuberans (DFSP) is an aggressive spindle cell neoplasm. It is associated with the chromosomal translocation, t(17:22), which fuses the COL1A1 and PDGFbeta genes. We determined the characteristic gene expression profile of DFSP and characterized DNA copy number changes in DFSP by array-based comparative genomic hybridization (array CGH). Fresh frozen and formalin-fixed, paraffin-embedded samples of DFSP were analyzed by array CGH (four cases) and DNA microarray analysis of global gene expression (nine cases). The nine DFSPs were readily distinguished from 27 other diverse soft tissue tumors based on their gene expression patterns. Genes characteristically expressed in the DFSPs included PDGF beta and its receptor, PDGFRB, APOD, MEOX1, PLA2R, and PRKCA. Array CGH of DNA extracted either from frozen tumor samples or from paraffin blocks yielded equivalent results. Large areas of chromosomes 17q and 22q, bounded by COL1A1 and PDGF beta, respectively, were amplified in DFSP. Expression of genes in the amplified regions was significantly elevated. Our data shows that: 1) DFSP has a distinctive gene expression profile; 2) array CGH can be applied successfully to frozen or formalin-fixed, paraffin-embedded tumor samples; 3) a characteristic amplification of sequences from chromosomes 17q and 22q, demarcated by the COL1A1 and PDGF beta genes, respectively, was associated with elevated expression of the amplified genes. 相似文献
77.
78.
Michael Wind Robert Graf Sabine Renker Hans Wolfgang Spiess 《Macromolecular chemistry and physics.》2005,206(1):142-156
Summary: The complex dynamics of poly(n‐alkyl methacrylates) is studied by advanced 13C NMR spectroscopy as well as mechanical and dielectric relaxation. Extended backbone conformations are identified as the molecular units involved in structural relaxation. From the variation in the degree of polymerization and a comparison with the presence of stereoregular sequences in the sample, the length of the extended units is determined to involve about five, at most ten monomeric units. Syndiotactic and isotactic sequences behave similarly. These findings are indicative of locally structured polymer melts.
79.
F. Duparc J. M. Thomine F. Dujardin C. Durand M. Lukaziewicz J. M. Muller P. Freger 《Surgical and radiologic anatomy : SRA》1997,19(2):61-67
The authors present a study of the intrinsic anatomy of the gluteus medius m. and of its innervation through the caudal branch of the superior gluteal n. The existence of an intramuscular tendon in the thickness of the gluteus medius was constantly prooved in 40 muscles. The relations of the intrinsic fibrous structure of the muscle and its innervation were studied. The authors deduce from that the topography of a gluteus medius incision, with respect to a safety area towards its innervation, which leads to an exposure of the acetabulum that is satisfying and gives opportunities of a sound repair after the surgery of the hip joint through the transgluteal approach. They propose the anterior hemimyotomy of the gluteus medius m designation.
Bases anatomiques de l'abord transglutéal de la hanche par hémimyotomie antérieure du muscle moyen fessier
Résumé Les auteurs présentent une étude de l'anatomie intrinsèque du m. moyen fessier (MF) et de son innervation par le rameau caudal du n. glutéal supérieur (NGS). 40 muscles ont été étudiés. L'existence d'une lame tendineuse dans l'épaisseur du MF a été constamment mise en évidence. Les rapports entre les éléments de l'architecture fibreuse intrinsèque du muscle et son innervation ont été étudiés. Les auteurs en déduisent la topographie d'une incision du MF respectant une zone de sécurité vis à vis de son innervation, procurant une exposition acétabulaire satisfaisante et des possibilités de réparation solide après chirurgie de l'articulation coxo-fémorale par voie d'abord transglutéale, et proposent la dénomination hémimyotomie antérieure du MF.相似文献
80.