全文获取类型
收费全文 | 239417篇 |
免费 | 15766篇 |
国内免费 | 993篇 |
专业分类
耳鼻咽喉 | 2588篇 |
儿科学 | 6139篇 |
妇产科学 | 4496篇 |
基础医学 | 29931篇 |
口腔科学 | 4406篇 |
临床医学 | 24671篇 |
内科学 | 50408篇 |
皮肤病学 | 3245篇 |
神经病学 | 24240篇 |
特种医学 | 10246篇 |
外国民族医学 | 13篇 |
外科学 | 37871篇 |
综合类 | 2565篇 |
现状与发展 | 1篇 |
一般理论 | 180篇 |
预防医学 | 16809篇 |
眼科学 | 5663篇 |
药学 | 15934篇 |
2篇 | |
中国医学 | 322篇 |
肿瘤学 | 16446篇 |
出版年
2023年 | 1241篇 |
2022年 | 1880篇 |
2021年 | 5414篇 |
2020年 | 3086篇 |
2019年 | 5126篇 |
2018年 | 6113篇 |
2017年 | 4506篇 |
2016年 | 4911篇 |
2015年 | 5789篇 |
2014年 | 8449篇 |
2013年 | 11384篇 |
2012年 | 17487篇 |
2011年 | 18223篇 |
2010年 | 10176篇 |
2009年 | 9434篇 |
2008年 | 16056篇 |
2007年 | 16833篇 |
2006年 | 16396篇 |
2005年 | 16251篇 |
2004年 | 15273篇 |
2003年 | 13932篇 |
2002年 | 13322篇 |
2001年 | 2083篇 |
2000年 | 1607篇 |
1999年 | 2129篇 |
1998年 | 2826篇 |
1997年 | 2252篇 |
1996年 | 1969篇 |
1995年 | 1802篇 |
1994年 | 1569篇 |
1993年 | 1539篇 |
1992年 | 1139篇 |
1991年 | 1056篇 |
1990年 | 943篇 |
1989年 | 878篇 |
1988年 | 810篇 |
1987年 | 750篇 |
1986年 | 764篇 |
1985年 | 800篇 |
1984年 | 1006篇 |
1983年 | 870篇 |
1982年 | 1091篇 |
1981年 | 1019篇 |
1980年 | 887篇 |
1979年 | 550篇 |
1978年 | 595篇 |
1977年 | 525篇 |
1976年 | 481篇 |
1975年 | 367篇 |
1974年 | 393篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
181.
Kerstin Schmidt Johannes Hoffend Annette Altmann Ludwig G Strauss Antonia Dimitrakopoulou-Strauss Britta Engelhardt Dirk Koczan J?rg Peter Thomas J Dengler Walter Mier Michael Eisenhut Uwe Haberkorn Ralf Kinscherf 《Journal of nuclear medicine》2006,47(3):543-551
Growth of malignant tumors is dependent on sufficient blood supply. Thus, inhibition of tumor angiogenesis is emerging as a promising target in the treatment of malignancies. Human angiostatin (hANG) is one of the most potent inhibitors of endothelial cell proliferation, angiogenesis, and tumor growth in vivo. However, its mechanisms operating in vivo are not well understood. METHODS: To obtain more information about functional changes in the angiogenic process, we established Morris hepatoma (MH3924A) cell lines expressing hANG (hANG-MH3924A). The effects of hANG expression on proliferation and apoptosis of human umbilical vein endothelial cells (HUVECs) were measured in coculture experiments in vitro. To evaluate changes in tumor perfusion and blood volume, H2 15O and 68Ga-DOTA-albumin (DOTA is 1,4,7,10-tetraazacyclododecane-N,N',N',N'-tetraacetic acid) were used for PET studies in vivo. Additionally, immunohistologic quantification of vascularization, apoptosis, and proliferation as well as gene array analyses were performed. RESULTS: Our in vitro experiments demonstrate reduced proliferation and increased apoptosis in HUVECs when being cocultured with hANG-MH3924A. In support, tumor growth of hANG-MH3924A is diminished by 95% in vivo. However, tumor perfusion and blood volume are increased in hANG-MH3924A corresponding to an increased microvessel density. Furthermore, hANG-transfected tumors show changes in expression of genes related to apoptosis, stress, signal transduction, and metabolism. CONCLUSION: hANG expression leads to inhibition of tumor growth, increased apoptosis, and changes in the expression of multiple genes involved in stress reactions, signal transduction, and apoptosis, which indicates a multifactorial reaction of tumors. An enhanced microvessel density is seen as part of these reactions and is associated with increased perfusion as measured by PET. 相似文献
182.
Michael Kendler Wolfgang Uter reas Rueffer Raffael Shimshoni Eckehardt Jecht 《Pediatric allergy and immunology》2006,17(2):141-147
Atopic eczema/dermatitis syndrome (AEDS) commonly often arises during early infancy. In several intervention studies a beneficial influence on AEDS course of certain intestinal bacteria, administered as 'probiotics', has been described. To evaluate the possible role of the natural intestinal microflora in children with allergic eczema/dermatitis syndrome regarding immediate type hypersensitivity to food allergens, children with food allergy (AAEDS, n = 68) have been compared with children without detectable food allergy (NAEDS, n = 25). All children (n = 93) in preschool age, mean age of 2.6 (+/-1.8) years, diagnosed with AEDS who were treated as inpatients in 2003 in a dermatological hospital were included. The correlation between fecal microflora, parasites and specific immunoglobulin E (IgE) antibodies against common food allergens was analyzed. A similar composition of intestinal microflora in children with AAEDS and NAAEDS was found. The food allergens that were most frequently detected were egg white, cow milk, casein, peanut and hazelnut. Furthermore, a significant association between IgE sensitization against important food allergens and components of the fecal microflora could not be demonstrated. With aging changes occur in the intestinal microbiota [Proteus/Klebsiella and age (rho = -0.607) and Enterococcus and age (rho = -0.428)]. In two subjects of the AAEDS group Blastocystis hominis was found. The composition of natural intestinal microflora in children with AAEDS and NAAEDS was similar. Hence, there is no evidence of a role of the intestinal microflora with regard to the development of infant (food) allergy in children with AEDS. The possible consequences for allergic diseases later in life require further investigation. 相似文献
183.
184.
Jennifer M Griffith James R Sorenson J Michael Bowling Tracey Jennings-Grant 《Health education & behavior》2005,32(5):613-626
The Enhancing Patient Prenatal Education study tested the feasibility and educational impact of an interactive program for patient prenatal genetic screening and testing education. Patients at two private practices and one public health clinic participated (N = 207). The program collected knowledge and measures of anxiety before and after use of the tool. Time in various prenatal visit activities was collected prior to and after the introduction of the education tool. Providers completed an assessment of their experiences with patients who had used the program. Results indicate that patient knowledge significantly increased from pre to post (p = .0001) with no increase in anxiety (p = .31). Time in clinic activities, including overall visit time, increased. A majority of providers indicated that the program disrupted clinic flow. This assessment suggests that the program increases patient knowledge and does not increase patient anxiety. However, challenges remain to using this program in a clinic setting. 相似文献
185.
186.
187.
188.
Quantitative autoradiographic analysis was used to identify regions in the brain of the male primate where androgen binding sites may be involved in the actions of testosterone. Three days after castration, adult male rhesus monkeys received a subcutaneous injection of either dihydrotestosterone propionate (DHTP, 20 mg, n = 6), testosterone propionate (TP, 100 mg, n = 2), or oil vehicle (control males, n = 4). Three hours later, 5 mCi [3H]testosterone was administered as an i.v. bolus. At 60 min, brains were rapidly removed and the left halves were used for autoradiography. In control males, highest percentages of labeled neurons (20-84% using a rigorous Poisson criterion) were observed in the ventromedial, arcuate and premammillary nuclei (n.) of the hypothalamus, medial preoptic n., bed n. of stria terminalis, intercalated mammillary n., lateral septal n. and the medial, cortical and accessory basal n. of the amygdala. Pretreatment with DHTP eliminated labeling in androgen target tissues of the genital tract, and reduced the percentages of labeled neurons to 4-22% of control values in the arcuate, lateral septal, premammillary and intercalated mammillary n., indicating that in these regions testosterone acted predominantly at androgen binding sites. However, in the medial preoptic n., the ventromedial hypothalamic n. and the accessory basal amygdaloid n., DHTP pretreatment resulted in much less blocking which, together with other data, suggested that in these sites, testosterone's actions involved aromatization and interaction with estrogen-binding sites. 相似文献
189.
Treatment of primary hypogonadism in men by the transdermal administration of testosterone 总被引:2,自引:0,他引:2
J C Findlay V Place P J Snyder 《The Journal of clinical endocrinology and metabolism》1989,68(2):369-373
We tested the efficacy of a thin flexible testosterone-impregnated membrane applied to the scrotum for the long term treatment of male hypogonadism. Ten men with primary hypogonadism were treated for 3 months (2 men) or 13 months (8 men). Serum testosterone concentrations increased in all 10 men, to within the normal range in 8. Serum dihydrotestosterone concentrations increased to supranormal values in all of the men, decreased to the normal range in 6, indicating the biological effectiveness of the testosterone in those subjects. Two men whose serum LH concentrations did not fall to normal had small or distorted scrotal surfaces. Seven of the 8 men whose serum testosterone concentrations became normal said that their hypogonadal symptoms were corrected by this treatment. We conclude that the transdermal administration of testosterone is an effective means of treating the majority of hypogonadal men who have a normal scrotum. 相似文献
190.
Ana L Hermogenes Michael Richardson Arinos Magalhaes Armando Yarleque Edith Rodriguez Eladio F Sanchez 《Toxicon》2006,47(4):490-494
Lachesis venom plasminogen activator (LV-PA) is a 33-kDa serine proteinase isolated from bushmaster (Lachesis muta muta) snake venom, which activates the fibrinolytic system in vitro. This study has examined the effect of the plasma proteinase inhibitor alpha2-macroglobulin (alpha2-M) towards LV-PA and compares it with the effect on tissue type plasminogen activator (t-PA). The proteolytic activity of LV-PA alone or previously incubated with human plasminogen (Plg) on the large molecular mass protein substrates, dimethylcasein (DMC) and fibrinogen (Fg) was completely inhibited by human alpha2-M. However, the synthetic peptides Tos-Gly-Pro-Lys-pNA and H-D-Pro-Phe-Arg-pNA (S-2302) were hydrolyzed with almost no reduction in rate. At pH 7.4 and 37 degrees C the proteinase (0.15 microM over 15 min) interacted with alpha2-M, and each mole of alpha2-M bound 2 mol of enzyme. Sodium dodecyl sulfate gel electrophoresis of reduced samples showed that the interaction of alpha2-M with either LV-PA or t-PA preincubated with Plg resulted in the formation of approximately 90 kDa fragments and high molecular mass complexes (Mr 180 kDa), generated by the incubation mixture (LV-PA or t-PA) and Plg. The data suggest that LV-PA is a direct-type PA and its fibrinolytic effect can be reduced by alpha2-M in vivo. 相似文献