全文获取类型
收费全文 | 10064篇 |
免费 | 624篇 |
国内免费 | 34篇 |
专业分类
耳鼻咽喉 | 121篇 |
儿科学 | 237篇 |
妇产科学 | 250篇 |
基础医学 | 1436篇 |
口腔科学 | 151篇 |
临床医学 | 925篇 |
内科学 | 2424篇 |
皮肤病学 | 218篇 |
神经病学 | 935篇 |
特种医学 | 213篇 |
外科学 | 1221篇 |
综合类 | 147篇 |
一般理论 | 12篇 |
预防医学 | 687篇 |
眼科学 | 235篇 |
药学 | 867篇 |
中国医学 | 26篇 |
肿瘤学 | 617篇 |
出版年
2023年 | 51篇 |
2022年 | 66篇 |
2021年 | 229篇 |
2020年 | 106篇 |
2019年 | 151篇 |
2018年 | 202篇 |
2017年 | 154篇 |
2016年 | 191篇 |
2015年 | 222篇 |
2014年 | 289篇 |
2013年 | 406篇 |
2012年 | 579篇 |
2011年 | 596篇 |
2010年 | 289篇 |
2009年 | 330篇 |
2008年 | 553篇 |
2007年 | 594篇 |
2006年 | 547篇 |
2005年 | 549篇 |
2004年 | 552篇 |
2003年 | 486篇 |
2002年 | 499篇 |
2001年 | 218篇 |
2000年 | 185篇 |
1999年 | 163篇 |
1998年 | 95篇 |
1997年 | 79篇 |
1996年 | 72篇 |
1995年 | 63篇 |
1994年 | 71篇 |
1993年 | 76篇 |
1992年 | 141篇 |
1991年 | 147篇 |
1990年 | 112篇 |
1989年 | 132篇 |
1988年 | 122篇 |
1987年 | 110篇 |
1986年 | 113篇 |
1985年 | 77篇 |
1984年 | 86篇 |
1983年 | 72篇 |
1982年 | 74篇 |
1981年 | 56篇 |
1980年 | 50篇 |
1979年 | 48篇 |
1978年 | 47篇 |
1977年 | 44篇 |
1976年 | 43篇 |
1975年 | 62篇 |
1971年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
81.
The unusual occurrence of very large cysticerci presenting as tumour-like lesions prompted this search of the pathology records of a south Indian hospital, to find similar cases. The maximum diameter of 187 consecutively diagnosed extraneural cysticerci, was recorded and those cases exceeding the mean by two standard deviations reviewed. Six biopsies showing cysticerci with a maximum diameter ranging from 4 to 11 cm, were identified, and hospital records and all pathological material available, were reexamined. The clinical differential diagnosis included benign and malignant tumours, hydatid cyst and haematoma. All the cysts were confirmed to be cysticerci, but species diagnosis was not possible by examining archival material. In an appropriate geographical setting, large cysticerci should form part of the differential diagnosis of cystic tumour-like lesions. An attemp can then be made, while the specimen is still fresh, to identify the species. 相似文献
82.
Vesicular stomatitis virus: mode of transcription. 总被引:44,自引:0,他引:44
83.
84.
Sporadic fundic gland polyps: common gastric polyps arising through activating mutations in the beta-catenin gene 总被引:1,自引:0,他引: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)
Abraham SC Nobukawa B Giardiello FM Hamilton SR Wu TT 《The American journal of pathology》2001,158(3):1005-1010
Fundic gland polyps (FGPs) are the most common gastric polyps. FGPs traditionally have been regarded as nondysplastic hamartomatous or hyperplastic lesions, but their pathogenesis remains unclear. We have recently shown that somatic adenomatous polyposis coli (APC) gene alterations are frequently present in FGPs associated with familial adenomatous polyposis (FAP), raising the possibility that mutations of the beta-catenin gene affecting the APC/beta-catenin pathway might be involved in the pathogenesis of sporadic FGPs. We analyzed somatic beta-catenin gene mutations in 57 sporadic FGPs from 40 patients without FAP and in 19 FGPs from 13 FAP patients. Direct DNA sequencing of exon 3 encompassing the glycogen synthase kinase-3beta phosphorylation region for beta-catenin was used with confirmation by HIN:fI restriction endonuclease digestion. The foveolar epithelium and dilated fundic glands of the polyps were separately microdissected and analyzed in 22 of 57 sporadic FGPs. Activating beta-catenin gene mutations were present in 91% (52 of 57) of sporadic FGPs. Both the foveolar epithelium and the dilated fundic gland epithelium comprising the polyps were shown to have the same somatic beta-catenin mutation in 21 of 22 (95%) sporadic FGPs. In contrast, beta-catenin gene mutations were not present in any of the 19 FAP-associated FGPs (P: < 0.000001). The high frequency of beta-catenin mutations in sporadic FGPs indicates that these lesions arise through activating mutations of the beta-catenin gene. Beta-catenin mutations in gastrointestinal tract polyps have previously only been demonstrated in a subset of adenomatous (dysplastic) or neoplastic polyps. Sporadic FGPs are therefore the only lesions of the gastrointestinal tract to demonstrate beta-catenin mutations while lacking dysplastic morphology. 相似文献
85.
Mast cells are traditionally known for mediating allergic reactions. In addition, these cells have been implicated in the
pathogenesis of a variety of clinical conditions such as atopic and contact dermatitis, bullous pemphigoid, fibrotic lung
disease, neurofibromatosis, psoriasis, scleroderma, rheumatoid arthritis, interstitial cystitis, ulcerative colitis, and Crohn’s
disease, but their role in host defense was an enigma until recently. Owing to the strategic location of mast cells at the
host environment interface, their role in bacterial infections has been studied by a number of investigators. Latest reports
show that mast cells have an ability to modulate the host’s innate immune response to infectious agents. This review discusses
the clinical implications of mast cell-bacteria interactions.
Received: 13 August 1997 / Accepted: 7 April 1998 相似文献
86.
Comparative genomic hybridization (CGH) analyses have detected gains of copy number on 13q, especially at 13q31-q32, in cell
lines and primary cases of various types of lymphoma. Since amplification of chromosomal DNA is one of the mechanisms that
can activate tumor-associated genes, and because 13q amplification had been reported in various other types of tumors as well,
we attempted to define by fluorescence in situ hybridization (FISH) a common region at 13q31-q32 in which to explore genes
that might be targets for the amplification events. Although the commonly amplified region we defined was relatively large
(approximately 4 Mb), only one true gene, GPC5, was found there. GPC5 was over-expressed in lymphoma cell lines that had shown amplification, in comparison with those that had not. Our findings
suggest that GPC5 is a likely target for amplification, and that over-expression of this gene may contribute to development and/or progression
of lymphomas and other tumors. 相似文献
87.
Allicin stimulates lymphocytes and elicits an antitumor effect: a possible role of p21ras 总被引:7,自引:0,他引:7
Patya M Zahalka MA Vanichkin A Rabinkov A Miron T Mirelman D Wilchek M Lander HM Novogrodsky A 《International immunology》2004,16(2):275-281
Allicin, the main organic allyl sulfur component in garlic, exhibits immune-stimulatory and antitumor properties. Allicin stimulated [(3)H]thymidine incorporation in mouse splenocytes and enhanced cell-mediated cytotoxicity in human peripheral mononuclear cells. Multiple administration (i.p.) of allicin elicited a marked antitumor effect in mice inoculated with B-16 melanoma and MCA-105 fibrosarcoma. The immune-stimulatory and antitumor effects of allicin are characterized by a bell-shaped curve, i.e. allicin at high, supra-optimal concentrations is less effective or inhibitory. Allicin induced activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) in human peripheral mononuclear cells, and also in wild-type Jurkat T-cells. Allicin failed to activate ERK1/2 in Jurkat T cells that express p21(ras), in which Cys118 was replaced by Ser. These cells are not susceptible to redox-stress modification and activation. We postulate that the immune stimulatory effect of allicin is mediated by redox-sensitive signaling such as activation of p21(ras). It is suggested that the antitumor effect of allicin is related to its immune-stimulatory properties. 相似文献
88.
Stein D Kurtsman L Stier S Remnik Y Meged S Weizman A 《Journal of affective disorders》2004,82(3):335-342
BACKGROUND: The knowledge available on electroconvulsive therapy (ECT) in adolescents is largely anecdotal, or based on findings from adults. The aim of the present study is to compare the use of ECT in adolescent and adult inpatients. METHODS: We retrospectively analyzed the files of all 36 adolescent (between the ages of 13 and 19) and 57 randomly selected adult inpatients (above the age of 20) treated with ECT in a university-affiliated mental heath center in Israel between 1991 and 1997. RESULTS: Sixty one percent of the adolescents improved by the end of treatment, and 53% were not hospitalized in the subsequent year. The respective percentages among adults were 83% and 49%. Whereas most adults were treated with ECT because of schizophrenic disorders, almost half of the adolescents received ECT for affective disorders. Significantly more adolescents were treated with ECT because of acute life-endangering conditions (catatonia or severe suicidal risk). No significant adverse effects were found in both groups. LIMITATIONS: Our study is based on a retrospective chart review. The adolescent and adult groups are different in psychiatric morbidity, diagnosis and outcome, have not been assessed in a blind manner, and we have not used standardized psychometric batteries for the evaluation of ECT-related memory disturbances. CONCLUSIONS: ECT may be an effective, well-tolerated and safe procedure in both adult and adolescent inpatients. 相似文献
89.
Purification and characterization of placental heparanase and its expression by cultured cytotrophoblasts 总被引:9,自引:2,他引:9
Goshen Ran; Hochberg Abraham A.; Korner Gill; Levy Ehud; Ishai-Michaeli Rivka; Elkin Michael; de Groot Nathan; Vlodavsky Israel 《Molecular human reproduction》1996,2(9):679-684
The role of different extracellular matrix (ECM)-degrading enzymesin the normal functioning of the placenta is well documented.Heparan sulphate proteoglycan (HSPG) is an integral constituentof the placental and decidual ECM. Because this proteoglycanspecifically interacts with various macromolecules in the ECM,its degradation may disassemble the matrix. Hence, in the caseof the placenta, this may facilitate normal placentation andtrophoblast invasion. Crude placental specimens were collectedfrom first and third trimester placentas. Heparanase (endo-P-glucuronidase)was isolated and purified by ammonium sulphate precipitationfollowed by sequential chromatographies on carboxymethyl-, heparin-and ConA-Sepharose columns. The placental enzyme was furthercharacterized for its molecular weight and specific inhibitionby heparin, and was shown to resemble heparanase expressed byhighly metastatic tumour cells and activated cells of the immunesystem. In order to locate the source of heparanase activityin the placenta, primary cytotrophoblast cultures were established.Intact cells, as well as conditioned medium and cell lysates,were analysed for heparanase activity using metabolically sulphate-labelledECM as a natural substrate. Heparanase was highly active inlysates of cytotrophoblasts. This activity was also expressedby intact cytotrophoblasts seeded on ECM, but no activity couldbe detected in the culture medium. Incubation of the cytotrophoblastsin contact with ECM resulted in release of ECM-bound basic fibroblastgrowth factor (bFGF). We propose that the cytotrophoblasticheparanase facilitates placentation, through cytotrophoblastextravasation and localized neovascularization. cytotrophoblast/extracellular matrix/heparanase/heparan sulphate proteoglycan/placenta 相似文献
90.
A protein kinase A-dependent molecular switch in synapsins regulates neurite outgrowth 总被引:5,自引:0,他引:5
Kao HT Song HJ Porton B Ming GL Hoh J Abraham M Czernik AJ Pieribone VA Poo MM Greengard P 《Nature neuroscience》2002,5(5):431-437
Cyclic AMP (cAMP) promotes neurite outgrowth in a variety of neuronal cell lines through the activation of protein kinase A (PKA). We show here, using both Xenopus laevis embryonic neuronal culture and intact X. laevis embryos, that the nerve growth-promoting action of cAMP/PKA is mediated in part by the phosphorylation of synapsins at a single amino acid residue. Expression of a mutated form of synapsin that prevents phosphorylation at this site, or introduction of phospho-specific antibodies directed against this site, decreased basal and dibutyryl cAMP-stimulated neurite outgrowth. Expression of a mutation mimicking constitutive phosphorylation at this site increased neurite outgrowth, both under basal conditions and in the presence of a PKA inhibitor. These results provide a potential molecular approach for stimulating neuron regeneration, after injury and in neurodegenerative diseases. 相似文献