全文获取类型
收费全文 | 3962篇 |
免费 | 267篇 |
国内免费 | 17篇 |
专业分类
耳鼻咽喉 | 13篇 |
儿科学 | 204篇 |
妇产科学 | 60篇 |
基础医学 | 440篇 |
口腔科学 | 113篇 |
临床医学 | 512篇 |
内科学 | 957篇 |
皮肤病学 | 33篇 |
神经病学 | 323篇 |
特种医学 | 379篇 |
外国民族医学 | 2篇 |
外科学 | 392篇 |
综合类 | 65篇 |
预防医学 | 214篇 |
眼科学 | 60篇 |
药学 | 265篇 |
1篇 | |
肿瘤学 | 213篇 |
出版年
2022年 | 27篇 |
2021年 | 57篇 |
2020年 | 30篇 |
2019年 | 44篇 |
2018年 | 68篇 |
2017年 | 54篇 |
2016年 | 58篇 |
2015年 | 82篇 |
2014年 | 108篇 |
2013年 | 142篇 |
2012年 | 158篇 |
2011年 | 165篇 |
2010年 | 106篇 |
2009年 | 127篇 |
2008年 | 138篇 |
2007年 | 123篇 |
2006年 | 146篇 |
2005年 | 144篇 |
2004年 | 142篇 |
2003年 | 123篇 |
2002年 | 122篇 |
2001年 | 129篇 |
2000年 | 130篇 |
1999年 | 133篇 |
1998年 | 113篇 |
1997年 | 108篇 |
1996年 | 107篇 |
1995年 | 79篇 |
1994年 | 83篇 |
1993年 | 66篇 |
1992年 | 88篇 |
1991年 | 78篇 |
1990年 | 76篇 |
1989年 | 99篇 |
1988年 | 73篇 |
1987年 | 83篇 |
1986年 | 71篇 |
1985年 | 67篇 |
1984年 | 61篇 |
1983年 | 48篇 |
1982年 | 28篇 |
1981年 | 32篇 |
1980年 | 33篇 |
1979年 | 44篇 |
1978年 | 32篇 |
1977年 | 28篇 |
1976年 | 33篇 |
1975年 | 15篇 |
1974年 | 17篇 |
1973年 | 20篇 |
排序方式: 共有4246条查询结果,搜索用时 15 毫秒
1.
PJ Commerford 《Cardiovascular journal of Africa》2015,26(4):151-Aug;26(4):151
2.
3.
Minorities and AIDS: knowledge, attitudes, and misconceptions among black and Latino adolescents. 总被引:4,自引:2,他引:2 下载免费PDF全文
White adolescents in San Francisco high schools were more knowledgeable than Black adolescents about the cause, transmission, and prevention of AIDS (acquired immunodeficiency syndrome), and Black adolescents were more knowledgeable than their Latino peers. Black and Latino adolescents were approximately twice as likely as White adolescents to have misconceptions about the casual transmission of AIDS. Less knowledge about AIDS and prevalent misconceptions were associated with greater levels of perceived risk of contracting AIDS. 相似文献
4.
Human lymphocytes that have been heat-inactivated (1 hr, 45 degrees C) were used as stimulator cells in a model system to study the requirements of allogeneic T cell activation in vitro. Cytotoxic T lymphocytes were not generated in either primary or secondary mixed lymphocyte cultures after exposure to heated stimulator cells. Successful reconstitution of cytolytic activity in primary cultures was achieved by the addition of rIL-2. Further, cytotoxic T cell lines could be maintained in culture for several weeks by stimulation with heated allogeneic cells and periodic addition of exogenous IL-2. The cytotoxic T cells generated in primary cultures or in the T cell lines were specific for the HLA class I antigens of the stimulating cells. Thus, the combination of heated cells and IL-2 stimulated antigen-specific cytotoxic cells, and not merely lymphokine-activated killers. Although IL-2 production appeared to be a crucial missing component of MLCs with heated lymphocytes, the addition of IL-1, a factor known to act as a second signal for stimulating IL-2 production, did not reconstitute cytolytic activity. These results indicate that (1) heat treatment does not appreciably affect class I structure; (2) HLA class I/T cell receptor interactions are intact, resulting in responsiveness to IL-2 but not IL-1; and (3) heating creates a defect that has a minimal effect on CTL precursor activation but does disrupt a T helper cell/stimulator cell interaction critical for IL-2 production. 相似文献
5.
6.
A double-blind comparison of fluoxetine, imipramine and placebo in outpatients with major depression 总被引:2,自引:0,他引:2
J P Feighner W F Boyer C H Merideth G G Hendrickson 《International clinical psychopharmacology》1989,4(2):127-134
Fluoxetine is the first selective serotonin reuptake inhibitor antidepressant to be marketed in the U.S. In this double-blind trial fluoxetine was compared with imipramine and placebo among 198 outpatients with DSM-III major depression, of whom 145 completed at least 2 weeks of active treatment and were evaluated for efficacy. Significantly fewer patients in each active drug group terminated early due to lack of efficacy compared to placebo. Both imipramine and fluoxetine were significantly superior to placebo on most measures. There were no consistently significant differences between the two active drugs although a trend favored imipramine on a number of measures. Fluoxetine was generally well tolerated. Significantly more imipramine than placebo patients terminated early due to side-effects while the fluoxetine-placebo difference was not significant. The results support previous studies which suggest fluoxetine's superior side-effect profile and the approximate antidepressant equivalence of fluoxetine and TCAs. 相似文献
7.
Severe hemorrhagic radiation proctitis advancing to gradual cessation with hyperbaric oxygen 总被引:3,自引:0,他引:3
Dr. Jacky Charneau MD Gilles Bouachour MD Bruno Person MD Pascal Burtin MD Jean Ronceray MD Jean Boyer MD 《Digestive diseases and sciences》1991,36(3):373-375
Summary We report a case of a male patient suffering from a severe hemorrhagic radiation proctitis which gradually ceased with hyperbaric oxygen. We discuss the mechanisms of chronic radiation injury and the effect of the hyperbaric oxygen. This therapy is proposed as an alternative to surgical intervention for this abnormality. 相似文献
8.
M Zentilin Boyer P de Lonlay N Seta M Besnard C Pélatan H Ogier J P Hugot C Faure J M Saudubray J Navarro J P Cézard 《Archives de pédiatrie》2003,10(7):590-595
Congenital disorders of glycosylation type I (GDG-I) is a class of genetic multisystem disorders characterised by defective glycosylation of glycoproteins. The characteristics and mechanisms of failure to thrive and intestinal diseases present in CDG-I are anectodal. PATIENTS AND METHODS: The aim of this study was to analyse 7 CDG-I (4 CDG-Ia, 2 CDG-Ib and 1 CDG-Ix) with important digestive symptoms and failure to thrive in order to characterise the mechanisms implied. RESULTS: Four children had no skin abnormality or dysmorphia (1 CDG-Ia, 2 CDG-Ib, 1 CDG-Ix). An encephalopathy with cerebellar hypoplasia was present only in the 4 CDG-Ia. Failure to thrive and diarrhea were present during the first month of life in 6 and appeared at 5 years in one CDG-Ia associated to mild or severe hepatopathy in all patients. One CDG-Ia, 1 CDG-Ib, 1 CDG-Ix had an exsudative enteropathy. A positive steatorrhea was present in 3 patients. Five patients had an abnormal small bowel biopsy. Abnormalities were variable: moderate inflammation of the chorion without villous atrophy in 2, intra-enterocyte fat accumulation without villous atrophy in 2, and partial villous atrophy with lymphangectasia in 1. In 2 CDG-Ia the intestinal biopsy was normal. Enteral nutrition in 4 and parenteral nutrition in 2 were effective in 4 patients and 1 patient with an exsudative enteropathy respond to a free fat diet (CDG-Ix). CONCLUSION: The digestive symptoms with failure to thrive is a common feature of CDG-I and could be the first symptoms. The diagnostic should be suspected if no other cause is found. Mechanisms of the intestinal symptoms appear to be multiple such as inflammation, abnormal enterocyte lipid transport or intestinal permeability related to the abnormal glycosylation of intestinal mucosa glycoproteins. 相似文献
9.
BACKGROUND. Although the ascites of patients with ovarian cancer has been reported to contain immunosuppressive factors, the identity and source of this activity has not been determined. Previously, the authors showed that conditioned media from two of four epithelial ovarian cancer cell lines inhibits proliferation of mitogen-stimulated human lymphocytes. The physical characteristics of the inhibitory substance are unlike those of peptide growth factors but closely resemble those of fibronectin. METHODS AND RESULTS. In the current study, it was found that the two ovarian cancer cell lines that produce the inhibitory substance have more fibronectin on the cell surface and secrete significantly more immunoreactive fibronectin into their culture media than the other two ovarian cancer cell lines. In addition, the immunosuppressive activity was bound to a gelatin-Sepharose affinity column, known to bind fibronectin. Finally, in ascites from 20 patients with advanced epithelial ovarian cancer, fibronectin levels correlated with the ability to inhibit proliferation of lectin-stimulated lymphocytes (P < 0.001). CONCLUSIONS. Fibronectin is produced by some ovarian cancer cell lines and acts to inhibit proliferation of mitogen-stimulated lymphocytes. Additional studies are needed to clarify the role of fibronectin in ovarian cancer. 相似文献
10.
Previous reports in the literature have described correlation of increasing repeat length with severity of the phenotype, in Kennedy syndrome. We describe male siblings with different repeat lengths, with lack of expression of the phenotype in the sibling with the longer repeat length. The phenotype was identical to motor neurone disease. There is variability of expression in Kennedy syndrome and repeat length even in siblings cannot be taken as a conclusive indicator of severity. CAG repeat length cannot be used to predict the natural history of Kennedy disease. The diagnosis of Kennedy syndrome should be considered in male patients presenting with atypical motor neurone disease. 相似文献