全文获取类型
收费全文 | 25408篇 |
免费 | 1940篇 |
国内免费 | 205篇 |
专业分类
耳鼻咽喉 | 283篇 |
儿科学 | 803篇 |
妇产科学 | 623篇 |
基础医学 | 3486篇 |
口腔科学 | 567篇 |
临床医学 | 2333篇 |
内科学 | 4761篇 |
皮肤病学 | 450篇 |
神经病学 | 1822篇 |
特种医学 | 802篇 |
外国民族医学 | 1篇 |
外科学 | 3379篇 |
综合类 | 587篇 |
一般理论 | 26篇 |
预防医学 | 3627篇 |
眼科学 | 558篇 |
药学 | 1667篇 |
2篇 | |
中国医学 | 142篇 |
肿瘤学 | 1634篇 |
出版年
2023年 | 215篇 |
2022年 | 402篇 |
2021年 | 708篇 |
2020年 | 352篇 |
2019年 | 604篇 |
2018年 | 735篇 |
2017年 | 511篇 |
2016年 | 551篇 |
2015年 | 634篇 |
2014年 | 862篇 |
2013年 | 1223篇 |
2012年 | 1716篇 |
2011年 | 1808篇 |
2010年 | 1073篇 |
2009年 | 847篇 |
2008年 | 1341篇 |
2007年 | 1461篇 |
2006年 | 1403篇 |
2005年 | 1222篇 |
2004年 | 1122篇 |
2003年 | 1055篇 |
2002年 | 959篇 |
2001年 | 578篇 |
2000年 | 529篇 |
1999年 | 505篇 |
1998年 | 191篇 |
1997年 | 185篇 |
1996年 | 145篇 |
1995年 | 126篇 |
1994年 | 113篇 |
1993年 | 108篇 |
1992年 | 343篇 |
1991年 | 308篇 |
1990年 | 308篇 |
1989年 | 293篇 |
1988年 | 288篇 |
1987年 | 261篇 |
1986年 | 241篇 |
1985年 | 244篇 |
1984年 | 176篇 |
1983年 | 140篇 |
1982年 | 89篇 |
1981年 | 102篇 |
1979年 | 118篇 |
1978年 | 76篇 |
1977年 | 73篇 |
1975年 | 71篇 |
1974年 | 99篇 |
1973年 | 97篇 |
1971年 | 77篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
Retinopathy of prematurity 总被引:13,自引:0,他引:13
Over the last decade major advances have been made in the understanding of the pathogenesis and evolution of retinopathy of prematurity (ROP). The increased survival of very small premature infants in modern neonatal intensive care units has led to the resurgence of this potentially blinding disease. ROP appears to be a multifactorial disease, the prevention of which is probably impossible even now, with the most accurate methods of blood gas monitoring and oxygen restriction. In addition to oxygen, there are a number of significant risk factors, such as birth weight and gestational age, ventilator hours, hyper and hypocarbia, hypoxia and acidosis, xanthine therapy and probably bright light. Current data suggest that the level of antioxidants in the immature retina is relatively low and therefore oxygen radicals which accumulate in the preterm baby's retina may play an important role in the pathogenesis of ROP. The treatment of the disease in both its "active" and "cicatricial" stages emphasizes the need for a new classification which could serve as a common international language through which results may be compared. Vitamin E was suggested in some studies to be helpful in preventing the severe stages of the disease, but its efficacy has yet to be proved. Treatment modalities such as photocoagulation, cryotherapy and vitrectomy are being tried as a means of therapy in the more advanced stages of the disease. Preliminary results of a large multicenter study support the efficacy of cryotherapy. 相似文献
112.
Carol Smillie B.N. B.Ed. M.S.C. Katherine Coffin B.A. ME.D. Kathryn Porter B.A. Brenda Ryan B.A. M.B.A. 《Journal of community health》1988,13(3):156-170
The International Conference on Primary Health Care, meeting in Alma-Ata, in the Soviet Union, September 12, 1978, expressed the need for urgent action by all governments, all health and development workers and the world community, to protect and promote the health of all people of the world. The world was caught by the phrase which emerged from this conference, Health For All by the Year 2000 and many have examined the articles of the Alma-Ata declaration and tried to implement them in their corner of the world. This paper describes a community-based smoking-cessation program which was implemented in the province of Nova Scotia, Canada, during the years 1980–1984. Primary to this project was the belief that people have the right and the duty to participate individually and collectively in planning and implementing their health care. This paper describes one community's effort in putting this belief into practice.Carol Smillie, B.N. BE.d. M.S.c. is an Assistant Professor at the School of Nursing, Dalhousie University, Halifax, Nova Scotia, Canada B3H 3J5, Katherine Coffin, BA, MEd is the Program Officer, Nova Scotia Office, Health Promotion Directorate Health and Welfare Canada, 5251 Duke Street, Halifax, Nova Scotia. Canada B3J 1P3. Kathryn Porter, B.A. (Gen)., is the Information and Education Coordinator, Nova Scotia Division Canadian Cancer Society. Brenda Ryan, B.A., M.B.A. is Program Evaluation Analysist, Nova Scotia Department of Health, 6088 Hollis Street, Halifax. Nova Scotia, Canada. This Project was funded by Health and Welfare Canada, Nova Scotia Department of Health, Nova Scotia Division Canadian Cancer Society, Requests for reprints should be addressed to: Professor Carol Smillie. 相似文献
113.
A Ben T Tanaka K Shiraiwa S Kobayashi A Kikuyama A Magome K Kawamura C Yamaguchi T Ehara K Miyazawa 《Hinyokika kiyo. Acta urologica Japonica》1989,35(12):2099-2105
In 1980, extracorporeal shock wave lithotripsy (ESWL) was incorporated as a nonsurgical method of stone removal in the cases of nephrolithiasis and rapidly found worldwide acceptance. Several devices commonly designated "second generation" lithotripters vs "first generation" Dornier HM3 are now under experimental or clinical trial. We report our clinical experience of ESWL using a Siemens Lithostar and compared it with that obtained using a Dornier HM3. One hundred patients were treated during the period of April through October, 1986 using an HM3, and 100 other patients were treated using a Lithostar from April to August, 1988. More cases were treated with a Lithostar than with a HM3. Nearly 10% of all patients treated by ESWL required additional therapeutic approaches (excepted ureteral stent) either with HM3 or Lithostar. However, in the cases of ureteral stone, with the Lithostar more cases required adjuvant procedures (TUL) than HM3. Significantly more shock waves were needed with Lithostar than HM3 for complete fragmentation of the same size of renal and ureteral stones. The stone-free rate during a one month period after ESWL was nearly the same for HM3 and Lithostar (HM3: 84.3%, Lithostar: 83.5%). Lithostar is a multifunctional lithotriptor which has most of the advantages required by the lithotripter. 相似文献
114.
Porter JD Merriam AP Leahy P Gong B Feuerman J Cheng G Khanna S 《Human molecular genetics》2004,13(3):257-269
115.
Bensafi M Porter J Pouliot S Mainland J Johnson B Zelano C Young N Bremner E Aframian D Khan R Sobel N 《Nature neuroscience》2003,6(11):1142-1144
Neural representations created in the absence of external sensory stimuli are referred to as imagery, and such representations may be augmented by reenactment of sensorimotor processes. We measured nasal airflow in human subjects while they imagined sights, sounds and smells, and only during olfactory imagery did subjects spontaneously enact the motor component of olfaction--that is, they sniffed. Moreover, as in perception, imagery of pleasant odors involved larger sniffs than imagery of unpleasant odors, suggesting that the act of sniffing has a functional role in creating of olfactory percepts. 相似文献
116.
Intestinal microvillous disorders are an uncommon cause of severe diarrhea, with very poor prognosis. The authors report the case of a female infant with Down syndrome, aganglionic megacolon, severe diarrhea, and jejunal biopsy with ultrastructural changes consistent with microvillous atrophy. The patient condition improved after a colostomy performed in the setting of the treatment of Hirschprung disease. 相似文献
117.
Nicholas E Jufas Ben Roediger Patricia J Armati 《Applied immunohistochemistry & molecular morphology》2008,16(1):83-86
The use of 2 monoclonal antibodies during double immunohistochemistry would enable the use of a greater variety of antibody combinations. Here, we demonstrate a simple, cost effective method of double indirect immunostaining of cultured cells using primary antibodies from the same species. This method uses microwaving of cell samples immediately after the application of the first secondary antibody, and significantly reduces the level of nonspecific staining. This technique does not elute the antibodies, nor raise the sample temperature above 37 degrees C. 相似文献
118.
Kallikrein 4 expression is up-regulated in epithelial ovarian carcinoma cells in effusions 总被引:1,自引:0,他引:1
Davidson B Xi Z Klokk TI Tropé CG Dørum A Scheistrøen M Saatcioglu F 《American journal of clinical pathology》2005,123(3):360-368
We immunohistochemically analyzed kallikrein 4 protein (hK4) expression in patients with epithelial ovarian carcinoma (181 malignant effusions and 103 solid carcinoma lesions). Expression of hK4 was also studied in 32 effusions using immunoblotting. Carcinoma cells expressed hK4 in 144 (79.6%) of 181 effusions and 85 (82.5%) of 103 solid tumors. Expression was seen in 51% or more of tumor cells in 70 effusions but often was limited to 5% or fewer cells in solid tumors (P = .009, primary tumors vs effusions; P = .002, metastases vs effusions). Immunoblotting showed hK4 expression in 31 of 32 specimens. Stromal cell hK4 expression, seen in 48 (46.6%) of 103 lesions, was significantly higher in primary tumors than metastases (26/43 vs 22/60, P = .019). hK4 expression in tumor cells was significantly lower in International Federation of Gynecology and Obstetrics stage IV than stage III tumors (P = .004, all lesions; P = .012, primary tumors). hK4 expression in carcinoma cells was associated with longer overall survival (not significant; P = .14, peritoneal effusions). hK4 is expressed widely in ovarian carcinoma; levels in carcinoma cells are highest in effusions, which might be related to loss of stromal contribution and/or altered microenvironment. hK4 expression in carcinoma cells of effusions or solid tumors does not predict survival. 相似文献
119.
Lymphoepithelioma-like carcinoma of the bladder: three cases with clinicopathological and p53 protein expression study 总被引:12,自引:0,他引:12
Izquierdo-García FM García-Díez F Fernández I Pérez-Rosado A Sáez A Suárez-Vilela D Guerreiro-González R Benéitez-Alvarez M 《Virchows Archiv : an international journal of pathology》2004,444(5):420-425
Lymphoepithelioma-like carcinoma of the bladder is an uncommon neoplasm, of which 49 cases have been described in the English literature, none of which has been studied for p53 protein expression. We studied three muscle-infiltrating cases of this tumor using immunohistochemical, in situ hybridization and polymerase chain reaction (PCR) methods. The three cases were positive for epithelial markers and negative for lymphoid antigens in the tumoral syncytial areas. The intensive infiltrate of small cells was negative for epithelial and positive for lymphoid markers. This population was mainly made up of cytotoxic T-lymphocytes, positive for TIA-1. p53 protein was intensely positive in more than 90% of the epithelial component nuclei, being negative in the lymphoid cells. PCR study did not show mutations on p53. Both lymphocytes and epithelium were negative for Epstein–Barr virus markers, such as the latent membrane protein and EBER (Epstein–Barr-encoded RNA). The prognosis was very good after radiotherapy and chemotherapy treatment, preserving the bladder despite the muscle infiltration. The presence of an intense cytotoxic T-lymphocyte population may be related to this good prognosis. Both aspects, p53 protein status and T-lymphoid population, had never been studied before in bladder lymphoepithelioma-like carcinoma. 相似文献
120.
Variations in Helicobacter pylori lipopolysaccharide to evade the innate immune component surfactant protein D 总被引:2,自引:0,他引:2
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)
Khamri W Moran AP Worku ML Karim QN Walker MM Annuk H Ferris JA Appelmelk BJ Eggleton P Reid KB Thursz MR 《Infection and immunity》2005,73(11):7677-7686
Helicobacter pylori is a common and persistent human pathogen of the gastric mucosa. Surfactant protein D (SP-D), a component of innate immunity, is expressed in the human gastric mucosa and is capable of aggregating H. pylori. Wide variation in the SP-D binding affinity to H. pylori has been observed in clinical isolates and laboratory-adapted strains. The aim of this study was to reveal potential mechanisms responsible for evading SP-D binding and establishing persistent infection. An escape variant, J178V, was generated in vitro, and the lipopolysaccharide (LPS) structure of the variant was compared to that of the parental strain, J178. The genetic basis for structural variation was explored by sequencing LPS biosynthesis genes. SP-D binding to clinical isolates was demonstrated by fluorescence-activated cell sorter analyses. Here, we show that H. pylori evades SP-D binding through phase variation in lipopolysaccharide. This phenomenon is linked to changes in the fucosylation of the O chain, which was concomitant with slipped-strand mispairing in a poly(C) tract of the fucosyltransferase A (fucT1) gene. SP-D binding organisms are predominant in mucus in vivo (P = 0.02), suggesting that SP-D facilitates physical elimination. Phase variation to evade SP-D contributes to the persistence of this common gastric pathogen. 相似文献