全文获取类型
收费全文 | 18877篇 |
免费 | 1313篇 |
国内免费 | 59篇 |
专业分类
耳鼻咽喉 | 310篇 |
儿科学 | 485篇 |
妇产科学 | 513篇 |
基础医学 | 2728篇 |
口腔科学 | 482篇 |
临床医学 | 1903篇 |
内科学 | 3663篇 |
皮肤病学 | 427篇 |
神经病学 | 1553篇 |
特种医学 | 778篇 |
外国民族医学 | 2篇 |
外科学 | 2618篇 |
综合类 | 419篇 |
一般理论 | 52篇 |
预防医学 | 1697篇 |
眼科学 | 453篇 |
药学 | 1179篇 |
中国医学 | 17篇 |
肿瘤学 | 970篇 |
出版年
2022年 | 97篇 |
2021年 | 278篇 |
2020年 | 142篇 |
2019年 | 257篇 |
2018年 | 319篇 |
2017年 | 250篇 |
2016年 | 280篇 |
2015年 | 325篇 |
2014年 | 440篇 |
2013年 | 824篇 |
2012年 | 954篇 |
2011年 | 1159篇 |
2010年 | 647篇 |
2009年 | 536篇 |
2008年 | 984篇 |
2007年 | 1043篇 |
2006年 | 965篇 |
2005年 | 975篇 |
2004年 | 1030篇 |
2003年 | 935篇 |
2002年 | 986篇 |
2001年 | 224篇 |
2000年 | 199篇 |
1999年 | 248篇 |
1998年 | 256篇 |
1997年 | 215篇 |
1996年 | 186篇 |
1995年 | 181篇 |
1994年 | 175篇 |
1993年 | 149篇 |
1992年 | 185篇 |
1991年 | 181篇 |
1990年 | 167篇 |
1989年 | 184篇 |
1988年 | 171篇 |
1987年 | 153篇 |
1986年 | 155篇 |
1985年 | 177篇 |
1984年 | 175篇 |
1983年 | 131篇 |
1982年 | 190篇 |
1981年 | 142篇 |
1980年 | 147篇 |
1979年 | 108篇 |
1978年 | 116篇 |
1977年 | 106篇 |
1976年 | 107篇 |
1974年 | 103篇 |
1973年 | 99篇 |
1972年 | 96篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Jacobo E. Mintzer M.D. Mark P. Rubert Ph.D. David Loewenstein Ph.D. Edgardo Gamez M.D. Agustin Millor L.C.S.W. Rocio Quinteros M.S. Linda Flores M.D. Meridith Miller R.N. Ph.D. Adrianne Rainerman Carl Eisdorfer Ph.D. M.D. 《Community mental health journal》1992,28(4):293-303
This study assessed Cuban-American Hispanic and White non-Hispanic daughters who were major caregivers for their mothers suffering from Alzheimer's Disease. Although patients in both ethnic groups did not differ in their level of cognitive and functional impairment, Cuban-American Hispanic patients were significantly more likely to be living in their daughters' homes while the White non-Hispanic patients resided in institutional settings. Caregivers were equivalent in their knowledge and utilization of community services, but Cuban-American daughters were significantly more aware of financial aid resources. Cuban-American patients were significantly more depressed than their White non-Hispanic counterparts with daughters showing similar but nonsignificant trends. The impact of cultural factors on caregiving is discussed. 相似文献
82.
Dorsoventral patterning of the Drosophila embryo requires Nudel, a large mosaic protein with a protease domain. Previous studies have implicated Nudel's protease domain as the trigger of a proteolytic cascade that activates the Toll signaling pathway to establish dorsoventral polarity in the embryo. However, the function of other regions of Nudel has been unclear. By using two-dimensional gel electrophoresis and site-directed mutagenesis, we have obtained evidence that the N-terminal region of Nudel contains a site for glycosaminoglycan (GAG) attachment that is required for dorsoventral patterning. Disruption of this site blocks a disulfide-based association between N- and C-terminal Nudel polypeptides and proteolytic activation of Nudel's protease domain. We discuss how a GAG chain on Nudel might be required for Nudel protease activation. 相似文献
83.
Carl Andrew Castro John B. Hogan Kimberly A. Benson Christina W. Shehata Michael R. Landauer 《Pharmacology, biochemistry, and behavior》1995,50(4):521-526
Experimental drugs and compounds that do not easily dissolve in water or saline are frequently combined with vehicles like solvents, detergents, or vegetable oils. Yet very little has been reported on the behavioral effects of vehicles. In this study, we assessed the effects of a vegetable oil (emulphor-620), two detergents (Tween-20 and Tween-80), and two solvents [dimethyl sulphoxide (DMSO) and ethanol] on the locomotor activity in CD2F1 male mice. Locomotor activity was monitored for 12 h after vehicle administration (IP). The concentrations for each vehicle were expressed as percent of vehicle in saline (v/v). Emulphor-620 did not affect locomotor activity at any concentration tested (2%, 4%, 8%, 16%, and 32%). Tween-20 significantly decreased locomotor activity at a concentration of 16% and Tween-80 at 32%. DMSO significantly decreased locomotor activity at concentrations of 32% and 64%. In contrast, ethanol produced a biphasic behavioral response: increased activity at a concentration of 16% and decreased activity at a concentration of 32%. These results will facilitate the selection and concentration of vehicles to be used in combination with experimental drugs or test agents. 相似文献
84.
Alexandros Zafiropoulos Eva Andersson Elias Krambovitis Carl A. K. Borrebaeck 《Journal of immunological methods》1997,200(1-2):181-190
The use of in vitro immunization technology for the generation of human antigen-specific antibodies has essentially resulted in low affinity IgM antibodies, resembling an in vivo primary immune response. We now describe a detailed reproducible protocol for a two-step in vitro immunization, which yields isotype switched, antigen-specific human antibodies. The immunizing antigen was a 30aa synthetic peptide, containing both a B (15aa V3 peptide of the HIV-1) and a T helper cell epitope (15aa peptide from tetanus toxin). The immunization protocol includes: (i) a selection procedure of donors with a memory T cell response against tetatus toxoid; (ii) immunization of mature naive peripheral B lymphocytes in two distinct phases, involving a primary and a secondary step. None of the donors which were examined after primary 7immunization showed at any time an IgG anti-V3 specific antibody response, while all the donors showed an IgM response. After the secondary immunization step, anti-V3 antibodies of both IgM and IgG isotypes were detected. The switch frequency event was high among the tested donors (5/8). 相似文献
85.
Henry Krum MD PhD Rochelle Goldsmith PhD Michelle Wilshire-Clement BSc Myron Miller MD Milton Packer MD 《The American journal of cardiology》1995,75(17):1284-1286
In conclusion, plasma levels of the endothelialderived vasoconstrictor endothelin-1 (but not those of other neurohormonal vasoconstrictor factors), measured during exercise correlated closely with objective variables of exercise capacity in patients with heart failure. These findings suggest that endothelin-1 may contribute to exercise intolerance in patients with heart failure, perhaps by limiting the ability of the peripheral vasculature to dilate during exercise. 相似文献
86.
87.
88.
Gert Jan Laarman Menco G. Niemeyer Albert V. G. Bruschke Fred J. Verzijlbergen T. Liam Go Ernst E. van der Wall Carl A. P. L. Ascoop 《European journal of nuclear medicine and molecular imaging》1989,15(5):239-243
To establish test specific normal limits for quantitative analysis of uptake and washout of 201Tl after dipyridamole infusion combined with low level exercise, 20 healthy volunteers were studied with low likelihood of coronary artery disease (CAD) assessed by a stepwise probability analysis based on age, sex, symptoms, resting electrocardiogram, and exercise electrocardiography. Likelihood of CAD in these volunteers was calculated as 1%. After dipyridamole infusion combined with low level exercise, one volunteer complained of headache; no other side effects were observed. There were no chest pain complaints. Maximal hemodynamic changes were achieved during the 6th and 7th min of the test. No ST segment depression was recorded. Visual analysis of the 201Tl scintigrams was normal in all volunteers. Mean regional washout at 4 h was 44.37%±2.11%. The regional washout in the 70° LAO view (46.65%±1.10%) was significantly higher than in the anterior and 30° LAO views (43.44%±1.50% and 43.02%±1.45%, respectively). Profiles of uptake and washout of 201Tl were different after dipyridamole infusion combined with low level exercise as compared to maximal exercise. Thus, in quantitative analysis of 201Tl scintigraphy after dipyridamole infusion in conjunction with low level exercise as applied in the present study, it is mandatory to use normal limits of uptake and washout of 201Tl derived from healthy volunteers who underwent the same combined protocol. 相似文献
89.
Donna Cohen Carl Eisdorfer Patricia Prinz James Leverenz Mark Davis 《Neurobiology of aging》1980,1(2):165-168
Immunologic changes have been reported in the dementing illnesses of mid and late life. The results of two studies of drug-free males meeting research diagnostic criteria for primary neuronal degeneration of the Alzheimer's type suggest that serum IgG levels decrease with the progression of dementia. Serum IgG levels were inversely correlated with duration of illness and the levels of psychiatric symptomatology. Performance on the mini-mental status examination was positively associated with serum IgG concentrations. 相似文献
90.
Immunolocalization of Fas and Fas ligand in the ovaries of women with polycystic ovary syndrome: relationship to apoptosis 总被引:6,自引:0,他引:6
Cataldo NA Dumesic DA Goldsmith PC Jaffe RB 《Human reproduction (Oxford, England)》2000,15(9):1889-1897
Both Fas (APO-1, CD95), an apoptosis-inducing receptor, and its ligand, Fas ligand (FasL, CD95L), have been localized to the ovary. Granulosa cell apoptosis occurs in antral follicular atresia. In polycystic ovary syndrome (PCOS), antral follicles accumulate with some atretic features. The ovarian expression of Fas and FasL was examined in PCOS by immunohistochemistry and correlated with immunodetection of apoptotic cells. Fas immunostaining was present in pre-antral follicle oocytes, some primary and secondary pre-antral follicle granulosa cells, and both granulosa and theca of antral follicles. Thecal staining persisted with advancing atresia, while granulosa staining declined. In antral follicles, abundant Fas-positive cells co-localized with scattered nuclei immunopositive for apoptosis. Ovarian vascular myocytes were strongly Fas-immunopositive. FasL immunostaining was present in pre-antral follicles in oocytes and variably in granulosa. In antral follicles, granulosa and thecal FasL staining increased with advancing atresia. Normal control ovaries showed follicular Fas and FasL staining patterns similar to those in PCOS, but vascular staining was less prominent. In one healthy follicle, Fas immunostaining was seen in the oocyte and weakly in mural granulosa and theca interna. The results suggest that in PCOS, an alteration in Fas-mediated apoptosis, does not cause abnormal folliculogenesis, but may promote ovarian vascular remodelling. 相似文献