首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2945篇
  免费   310篇
  国内免费   21篇
耳鼻咽喉   20篇
儿科学   114篇
妇产科学   31篇
基础医学   336篇
口腔科学   150篇
临床医学   385篇
内科学   519篇
皮肤病学   131篇
神经病学   189篇
特种医学   197篇
外科学   289篇
综合类   177篇
一般理论   4篇
预防医学   239篇
眼科学   9篇
药学   229篇
中国医学   3篇
肿瘤学   254篇
  2022年   21篇
  2021年   33篇
  2020年   28篇
  2019年   41篇
  2018年   35篇
  2017年   50篇
  2016年   39篇
  2015年   47篇
  2014年   67篇
  2013年   106篇
  2012年   122篇
  2011年   134篇
  2010年   88篇
  2009年   96篇
  2008年   125篇
  2007年   114篇
  2006年   118篇
  2005年   106篇
  2004年   115篇
  2003年   83篇
  2002年   88篇
  2001年   82篇
  2000年   66篇
  1999年   84篇
  1998年   78篇
  1997年   68篇
  1996年   63篇
  1995年   37篇
  1994年   39篇
  1993年   44篇
  1992年   80篇
  1991年   85篇
  1990年   72篇
  1989年   72篇
  1988年   60篇
  1987年   67篇
  1986年   54篇
  1985年   56篇
  1984年   42篇
  1983年   38篇
  1982年   44篇
  1981年   33篇
  1979年   49篇
  1978年   30篇
  1977年   27篇
  1976年   23篇
  1975年   27篇
  1974年   20篇
  1971年   20篇
  1970年   25篇
排序方式: 共有3276条查询结果,搜索用时 15 毫秒
51.
In a drug discrimination paradigm pigeons and rats were trained with an operant procedure to discriminate between the presence and absence of the effects of 9-THC (1.0 and 3.0 mg/kg, injected IM 90 min and I.P. 30 min before the start of the session). Once trained, various THC metabolites as well as a water-soluble derivative of THC (SP-111), were substituted for 9-THC to test for generalization to the training drug. Generalization to 9-THC occurred with the 11-hydroxy metabolites and the potency order was 11-OH-9-THC >11-OH-8-THC 9-THC. Among the other metabolites tested (8-OH-9-THC, 8, 11-di-OH-9-THC, 8-OH-9-THC, 8, 11-di-OH-9-THC), it was only 11-di-OH-9-THC that completely substituted for 9-THC in pigeons, albeit at very high dose levels (rats were not tested with these metabolites). SP-111 generalized to 9-THC in both species. However, the onset of action of SP-111 was slower than that for 9-THC, especially in pigeons. These studies show the importance of obtaining complete dose-effect determinations over time when assessing structure-activity relationships with drug-discrimination procedures.A brief account of the results, which are summarized in Neuropharmacology 18:1023–1024, 1979), was presented at the British Association for Psychopharmacology Summer Conference, July 15–17, Birmingham, England, 1979  相似文献   
52.
We report here a patient with acute mycloid leukaemia who relapsed 20 months after undergoing a double autograft procedure in first remission. He was reinduced and subsequently underwent a third autologous bone marrow transplantation in second remission using bone marrow harvested in second remission and a Busulphan and Cyclophosphamide conditioning regimen. Although the engraftment was very slow, he has remained in second remission for 34+ months. This case demonstrates that durable disease-free survival can be attained by a second preparative therapy, even in second remission, for patients relapsed after autologous bone marrow transplantation.  相似文献   
53.
It has been demonstrated recently in mycosis fungoides and lichen planus that T lymphocyte subsets may be identified in cutaneous lymphocytic infiltrates using the immunoperoxidase technic in conjunction with monoclonal antibodies produced by the technic of Kohler and Milstein. This communication describes the application of this technic to cutaneous lymphoid infiltrates of parapsoriasis in which T cell predominance has been demonstrated previously. The lymphoid infiltrates of six patients with atrophic parapsoriasis were examined by the indirect immunoperoxidase technic using monoclonal antibodies (from two commercial sources) directed against "helper" and "suppressor" T cell subsets. Both "helper" and "suppressor" cells (as defined by a positive reaction with monoclonal antibodies) could be identified in cutaneous infiltrates. "Helper" cells predominated, but in varying degrees among patients. The relevance of these findings in relation to the possible development of clinical mycosis fungoides from atrophic parapsoriasis is discussed. In addition, factors causing difficulty in the consistent identification of cell subtypes are discussed. These factors suggest that in the present state of imperfection, difficulty will be experienced in using this technic for the accurate quantification of percentages of lymphocyte subsets in tissue sections.U  相似文献   
54.
Pigeons responding under a variable-interval (VI) 75-s schedule of food presentation were used to study cross-tolerance from 9-tetrahyrocannabinol (9-THC) to pentobarbital and barbital. After initial dose-effect functions for pentobarbital and barbital were determined, the birds received 9-THC injections for 6 weeks. This chronic administration regimen resulted in a greater than 100-fold tolerance to 9-THC. Redetermination of the pentobarbital and barbital dose-effect functions during the chronic 9-THC regimen revealed statistically significant shifts to the right for the pentobarbital (0.191 log unit) and barbital (0.078 log unit) dose-effect curves. All six birds showed tolerance to pentobarbital, while four of the six showed tolerance to barbital. Blood barbital levels before and after chronic 9-THC administration did not differ significantly. Tolerance to 9-THC was more prolonged and of much greater magnitude than the cross-tolerance to pentobarbital or barbital. The results demonstrate that cross-tolerance can develop from 9-THC to a barbiturate that normally undergoes little metabolism.  相似文献   
55.
56.
57.
The present study examined the degree to which event related rumination, a quest orientation to religion, and religious involvement is related to posttraumatic growth. Fifty-four young adults, selected based on prescreening for experience of a traumatic event, completed a measure of event related ruminations, the Quest Scale, an index of religious participation, and the Posttraumatic Growth Inventory. The three subscales of the Quest Scale, the two groups of rumination items (soon after event/within past two weeks), and the index of religious participation were entered in a standard multiple regression with the total score of the Posttraumatic Growth Inventory as the dependent variable. The degree of rumination soon after the event and the degree of openness to religious change were significantly related to Posttraumatic Growth. Congruent with theoretical predictions, more rumination soon after the event, and greater openness to religious change were related to more posttraumatic growth. Present findings offer some confirmation of theoretical predictions, and also offer clear direction for further research on the relationships of religion, rumination, and posttraumatic growth.  相似文献   
58.
OBJECTIVE: To assess the efficacy of a longer acting preparation of the gonadotrophin releasing hormone (GnRH) analogue goserelin (Zoladex LA, 10.8 mg) in 12 girls with central precocious or early puberty. METHODS: Two girls started treatment de novo; the remainder had been on suppressive treatment for a median duration of 1.5 (range, 0.2-5.6) years. Assessment comprising auxology, pubertal staging, and pelvic ultrasound examination was carried out at weeks 0, 4, 8, 10, and 12 (first cycle) and weeks 8, 10, and 12 (second cycle) to evaluate the required injection frequency. Thereafter, assessment was performed on the day of injection. Zoladex LA was given every 12 weeks unless pubertal progression occurred. RESULTS: Satisfactory control was achieved in eight patients using this regimen, and three patients required more frequent injections. One girl was removed from the study because of clinical progression and extreme mood swings. No serious adverse effects occurred. Mean height velocity during the study period was 4.5 cm/year (range, 3.1-6.6) compared with 6.5 cm/year (range, 3.8-9.6) before treatment in nine patients for whom data were available. CONCLUSIONS: Zoladex LA was effective in controlling precocious puberty in girls when given at intervals of 9-12 weeks and it is recommended that an initial assessment is made eight weeks after beginning treatment.  相似文献   
59.
The beta2 integrin (CD 18/CD 11 a, b, c) family of proteins mediate adherence of leukocytes to vascular endothelium and the associated ligand, intercellular adhesion molecule-1 (ICAM-1; CD 54), interacts with beta2 integrin proteins to allow transendothelial migration of leukocytes into sites of inflammation. The present study examines the function of these proteins in a murine model of acute cutaneous inflammation induced following topical application of 12-O- tetradecanoylphorbol-13-acetate (TPA) to the dorsal epidermis of SENCAR mice and in a model of skin multistage carcinogenesis. At 24 h following topical application of TPA to the dorsal epidermis of mice, dermal leukocytes expressed higher levels of beta2 integrin protein compared with the lower levels of beta2 integrin protein expression by peripheral blood leukocytes. ICAM-1 protein was localized to epidermal keratinocytes and vascular endothelium in TPA-treated skin and to proliferating papilloma cells. Intravenous (i.v.) injection of either 50 microg anti-beta2 integrin antibody alone or in combination with anti-ICAM-1 antibody significantly inhibited both TPA-stimulated neutrophil infiltration into the dermis (P < 0.001) and myeloperoxidase (MPO) activity (P < 0.03 anti-beta2 integrin antibody; P < 0.01 anti- beta2 integrin + ICAM-1 adhesion molecule antibodies), but had no effect on TPA-induced epidermal hyperplasia. In addition, injection of either anti-ICAM-1 adhesion molecule antibody alone (P < 0.004) or in combination with anti-beta2 integrin antibody (P < 0.001) significantly inhibited TPA-induced production of 7,8-dihydroxy-2'-deoxyguanosine (8- OHdG) immunoreactive proteins by epidermal keratinocytes. Beta2 integrin/ICAM-1 adhesion molecules work in concert to regulate migration, retention and functional activation of leukocytes within the dermis during TPA-induced skin inflammation and within stromal tissue of papillomas that form during multi-stage carcinogenesis. Agents that inhibit these receptor/ligand interactions may be useful in defining the roles of specific cell populations in cutaneous inflammation and multistage carcinogenesis and may also have potential as anti-promoting and anti-progression agents.   相似文献   
60.
Inactivation of the p53 tumor suppressor gene has been implicated in the pathogenesis of numerous human cancers, including osteosarcomas. Appendicular osteosarcomas of the dog appear to be a good model for their human equivalent with regard to biologic behavior, epidemiology and histopathology. We individually screened exons 5-8 of the p53 gene for mutations in 15 canine appendicular osteosarcomas using 'Cold' SSCP to compare the role of this gene in human and canine osteosarcoma tumorigenesis. Seven of the tumors (47%) exhibited point mutations, with one tumor possessing two mutations within different exons. Of these, seven were missense mutations and the eighth was a 'silent' mutation potentially affecting the exon 6-7 splicing region. Five of the missense mutations were located in highly conserved regions IV and V, while another corresponded with the highly conserved codon 220 mutational hotspot located outside the conserved domains. The locations and types of mutations were nearly identical to those reported in human cancer. These findings provide strong evidence of the involvement of p53 mutations in the development of canine appendicular osteosarcomas. Canine osteosarcomas appear to be a promising model for their human equivalent on a clinical, pathologic, and molecular level.   相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号