全文获取类型
收费全文 | 6313篇 |
免费 | 414篇 |
国内免费 | 6篇 |
专业分类
耳鼻咽喉 | 99篇 |
儿科学 | 175篇 |
妇产科学 | 236篇 |
基础医学 | 1003篇 |
口腔科学 | 84篇 |
临床医学 | 685篇 |
内科学 | 1307篇 |
皮肤病学 | 120篇 |
神经病学 | 692篇 |
特种医学 | 328篇 |
外科学 | 830篇 |
综合类 | 50篇 |
一般理论 | 1篇 |
预防医学 | 288篇 |
眼科学 | 122篇 |
药学 | 288篇 |
中国医学 | 12篇 |
肿瘤学 | 413篇 |
出版年
2022年 | 49篇 |
2021年 | 89篇 |
2020年 | 60篇 |
2019年 | 85篇 |
2018年 | 94篇 |
2017年 | 69篇 |
2016年 | 96篇 |
2015年 | 140篇 |
2014年 | 190篇 |
2013年 | 236篇 |
2012年 | 324篇 |
2011年 | 336篇 |
2010年 | 233篇 |
2009年 | 181篇 |
2008年 | 307篇 |
2007年 | 309篇 |
2006年 | 326篇 |
2005年 | 306篇 |
2004年 | 274篇 |
2003年 | 249篇 |
2002年 | 230篇 |
2001年 | 241篇 |
2000年 | 224篇 |
1999年 | 174篇 |
1998年 | 73篇 |
1997年 | 45篇 |
1996年 | 60篇 |
1995年 | 54篇 |
1994年 | 42篇 |
1993年 | 51篇 |
1992年 | 116篇 |
1991年 | 125篇 |
1990年 | 115篇 |
1989年 | 100篇 |
1988年 | 94篇 |
1987年 | 84篇 |
1986年 | 65篇 |
1985年 | 75篇 |
1984年 | 55篇 |
1983年 | 41篇 |
1982年 | 31篇 |
1979年 | 60篇 |
1978年 | 31篇 |
1977年 | 39篇 |
1975年 | 32篇 |
1974年 | 41篇 |
1973年 | 43篇 |
1972年 | 45篇 |
1971年 | 37篇 |
1968年 | 29篇 |
排序方式: 共有6733条查询结果,搜索用时 11 毫秒
31.
The aim of the double-blind, placebo-controlled study was to investigate the effects of a continuous combined estrogen-progestogen treatment (Climodien, Lafamme) as compared with estrogen alone on vigilance in insomniac postmenopausal syndrome patients, objectified by EEG mapping. METHODS: In a 3-arm, 2-month parallel group design phase, patients received a combination of estradiol valerate 2 mg and the novel progestogen dienogest 3 mg (Climodien 2/3) or estradiol valerate 2 mg alone or placebo. In a subsequent open-label phase, all patients received estradiol valerate 2 mg+dienogest 2 mg (Climodien 2/2). EEG mapping was carried out before and after the 2-month double-blind phase as well as after the 2-month open-label treatment. RESULTS: As compared with placebo, Climodien 2/3 induced a marked and highly significant increase in absolute power in all frequency bands, specifically in alpha-2 activity. Moreover, a significant increase in relative alpha-2 power, a decrease in relative delta and beta power as well as an acceleration of the dominant frequency and of the delta and alpha centroids suggested a marked improvement in vigilance. In contrast, under estradiol valerate 2 mg alone, only a slight augmentation of alpha and attenuation of relative delta and beta power occurred, suggesting only a slight vigilance improvement as compared with placebo. Thus, dienogest 2 mg increased the estrogen effect, which was also confirmed by a statistical evaluation of the differences between Climodien 2/3 and estradiol valerate alone (augmentation of alpha-2, attenuation of relative beta, acceleration of the dominant frequency). Moreover, Climodien 2/2 also markedly increased alpha-2 power, decreased relative beta-2 power and accelerated the alpha centroid. Finally, comparing Climodien 2/3 with Climodien 2/2, there was even a dose-efficacy relation. CONCLUSIONS: Estradiol valerate 2 mg improves vigilance slightly, thereby confirming previous findings. The additional administration of dienogest does not minimize the effect of estrogen, but on the contrary increases it, which makes the combination superior to both placebo and estradiol valerate alone. Vigilance improvement may be of great therapeutic benefit to menopausal syndrome patients at a time when increased adaptability is needed to adjust to increasing sexual, marital, occupational and social difficulties known to occur specifically in this period of life. 相似文献
32.
Five modern bicycle helmets were studied to elucidate some of the variations in ventilation performance, using both a heated manikin headform and human subjects (n=7). Wind speed and head angle were varied to test their influence on the measured steady-state heat exchange (cooling power) in the skull section of the headform. The cooling power transmitted by the helmets varied from about 60% to over 90% of that of the nude headform, illustrating the range of present manufacturer designs. Angling the head forward by 30° was found to provide better cooling power to the skull (up to 25%) for three of the helmets and almost equal cooling power in the remaining two cases. Comparisons of skull ventilation at these angles with human subjects strongly supported the headform results. 相似文献
33.
Kok Yvette J.M.de; Merkx Gerard F.M.; van der Maarel Silvere M.; Huber Irene; Malcolm Susan; Ropers Hans-Hilger; Cremers Frans P.M. 《Human molecular genetics》1995,4(11):2145-2150
X-linked deafness with stapes fixation (DFN3) is caused by mutationsin the POU3F4 gene at Xq21.1. By employing pulsed field gelelectrophoresis (PFGE) we identified a chromosomal aberrationin the DNA of a DFN3 patient who did not show alterations inthe open reading frame (ORF) of POU3F4. Southern blot analysisindicated that a DNA segment of 150 kb, located 170 kb proximalto the POU3F4 gene, was duplicated. Fluorescence in situ hybridization(FISH) analysis, PFGE, and detailed Southern analysis revealedthat this duplication is part of a more complex rearrangementincluding a paracentric inversion involving the Xq21.1 region,and presumably the Xq21.3 region. Since at least two DFN3-associatedminideletions are situated proximal to the duplicated segment,the inversion most likely disconnects the POU3F4 gene from aregulatory element which is located at a distance of at least400 kb upstream of the POU3F4 gene. 相似文献
34.
T W Huber S Storms P Young L E Phillips T E Rogers D G Moore R P Williams 《Journal of clinical microbiology》1983,17(3):405-409
Seroreactivity of sera from 109 patients with first-infection primary syphilis was 98.2% in the fluorescent treponemal antibody absorption test, 92.7% in the rapid plasma reagin 18-mm circle card test, 72.5% in the microhemagglutination test (MHA-TP), and 72.5% in the Venereal Disease Research Laboratory test. Seroreactivity of sera from 18 patients with primary syphilis with documented previous infection(s) was 100% in the fluorescent treponemal antibody absorption test, the rapid plasma reagin 18-mm circle card test, and the MHA-TP test and 88.9% in the Venereal Disease Research Laboratory test. The MHA-TP test failed to confirm reactivity in 13 of 79 sera which were reactive in the Venereal Disease Research Laboratory test and in 24 of 101 sera which were reactive in the rapid plasma reagin 18-mm circle card test. Testing another production lot of MHA-TP reagents resulted in even poorer correlation. The reactivity of the MHA-TP test in primary syphilis appeared to vary with the sensitivity of the production lot of reagents. 相似文献
35.
Cell-mediated immune responses between HLA-identical siblings: recognition of antigenic changes associated with acute myelogenous leukaemia. 下载免费PDF全文
Cell-mediated immune reactions between a patient suffering from acute myelogenous leukaemia (AML) and an HLA-identical sibling were studied in order to characterize the in vitro reactions in MLC and CML prior to bone marrow transplantation. Our results indicated that antigenic differences were detectable between the blasts and the remission lymphocytes. While the normal sibling did not respond in MLC to her HLA-identical sister's remission lymphocytes, there was an anti-blast response. This proliferative response, however, did not lead to the development of detectable cytotoxic cells capable of destroying blast cells. Unrelated individuals, on the other hand, responded strongly both in MLC and CML to the allogeneic tumour blasts and remission lymphocytes of the patient and the lymphocytes of the healthy sibling. The kinetics and magnitude of the MLC response to blast cells was different from that to remission lymphocytes. This response indicated that the blast cells expressed antigenic differences which were recognized in MLC by both the HLA-identical sibling and unrelated individuals. Furthermore, these tumour cells were capable of sensitizing allogeneic, but not syngeneic lymphocytes to become cytotoxic, though they seemed to be more resistant to destruction in CML than normal cells. 相似文献
36.
A simple rosette assay for demonstration of complement receptor sites using complement-coated zymosan beads. 总被引:2,自引:0,他引:2
In the present article we describe a simple rosette assay for detection of C3 receptor-bearing B lymphocytes with complement (C)-coated zymosan (Zy) beads. Zy coated with murine or human C bound to a distinct population of human and mouse lymphocytes as well as to the majority of lymphoblastoid cells of several human established cell lines. Rosette formation was also observed with human red blood cells, with human monocytes and neutrophils. Experiments with anti-immunoglobulin sera, with other B and T cell markers and with mouse thymocytes proved that the capacity to bind C-coated Zy is primarily a feature of B lymphocytes. The following findings suggested that C-coated Zy is bound via receptor sites for the activated components of C3: (a) Zy coated with C3-deficient serum failed to bind, (b) comparable percentages of various lymphoid and nonlymphoid cells formed rosettes with C-coated Zy as well as with antibody and C-coated sheep red blood cells, and (c) antibodies against human or murine C3 inhibited the binding of C-coated Zy. 相似文献
37.
M L Landry D Ferguson S Cohen K Huber P Wetherill 《Journal of clinical microbiology》1995,33(1):257-259
Blood samples held at either 4 degrees C or room temperature for 1 day had similar mean decreases in number of cytomegalovirus antigenemia-positive cells (52 to 55%) and similar false-negative test results (13 to 14%). After 2 days, samples held at 4 degrees C showed no further decline, whereas samples held at room temperature had a mean 81% decrease in positive cells, a 32% false-negative rate, and a more marked deterioration in cell morphology. 相似文献
38.
Coxsackievirus B-3 myocarditis in Balb/c mice. Evidence for autoimmunity to myocyte antigens. 总被引:15,自引:11,他引:15 下载免费PDF全文
Male Balb/c mice inoculated with a heart-adapted variant of Coxsackievirus, group B, type 3 (Nancy) (CVB3M), develop extensive myocarditis and cytolytic activity to primary cultures of uninfected and infected myocytes. To elucidate the mechanisms of myocyte injury in myocarditis, two distinct cytolytic T-lymphocyte (CTL) populations were isolated by immunoadsorption of lymph node cells to glutaraldehyde-fixed uninfected and infected myocyte monolayers. One population preferentially adsorbed to and lysed uninfected myocytes (autoreactive CTLs), while the other adsorbed to and lysed CVB3M-infected myocytes (virus-specific CTL). Neither CTL population adsorbed to monolayers of HeLa, L929, or umbilical cord endothelial cells, or to myocytes infected with a related but nonmyocarditic Coxsackievirus B-3 variant ( CVB3o ). While both autoreactive and virus-specific CTLs induced myocarditis in vivo, the lesions caused by autoreactive CTLs were more extensive and necrotizing than those of virus-specific cells. These results support the hypothesis that CVB3 -induced myocarditis results, in part, from autoimmunity to myocyte antigens. 相似文献
39.
R. Finke R. Gross E. Hackenthal J. Huber H. R. Kirchheim 《Pflügers Archiv : European journal of physiology》1983,399(2):102-110
- The effect of varying renal artery pressure between 160 and 40 mm Hg on renal blood flow and renin release was studied in seven conscious foxhounds under β-adrenergic blockade receiving a normal sodium diet (4.1 mmol/kg/day). Pressure was either increased by bilateral common carotid occlusion or reduced in steps and maintained constant by a control-system using an inflatable renal artery cuff. Carotid occlusion itself had no influence on renal blood flow and renin release when renal artery pressure was kept constant and the β-receptors in the kidney were blocked.
- Between 160 mm Hg and resting pressure there was no change in renal blood flow; between resting blood pressure and the lower limit of autoregulation (average 63.9 mm Hg) renal blood flow increased slightly (average 7%) indicating a high efficiency of renal blood flow autoregulation.
- The relationship between renal artery pressure and renin release could be approximated by two linear sections:a low sensitivity to a pressure change (average slope: ?0.69 ±0.26ng AI/min/mm Hg) was found above a threshold pressure (average: 89.8±3.3 mm Hg) and a high sensitivity to a pressure change (average slope: ?64.4±20.8 ng AI/ min/mm Hg) was observed between threshold pressure and 60 mm Hg. There was no further increase of renin release between 60 and 40 mm Hg.
- It is concluded that within the autoregulatory plateau the kidney of a conscious β-blocked dog receiving a normal sodium diet releases only negligible amounts of renin until renal artery pressure falls below a threshold pressure of 90 mm Hg which is close to the animals resting systemic pressure. Since beyond that a decrease of systemic pressure by as little as 1.3 mm Hg below threshold can raise resting renin release (84.8±29.8 ng/min) by 100%, it is suggested that systemic blood pressure tends to stabilize at a level at which renin release is minimal.
40.
The variable fragment (Fv) of the monoclonal B1-8 antibody recognizes 3-nitro-4-hydroxy-phenylacetate (NP) and 5-iodo-NP (NIP) allowing for the affinity purification of the respective B cell antigen receptor with NP-sepharose and its specific elution with NIP-capronic acid (NIPcap). We generated an intracellular single-chain B1-8 Fv (iscFv), fused it to the N-terminus of the regulatory subunit (p85alpha) of phosphatidylinositol-3-kinase (PI3K) (isc-p85alpha), and examined the potential of this iscFv to serve as an intracellular elutable protein purification tag. The isc-p85alpha fusion protein could be specifically affinity-purified from the lysates of transfected Drosophila S2 cells with NP-sepharose and eluted with NIPcap, indicating the functional folding of the iscFv in the reducing environment of the cytosol. Furthermore, co-purification of the catalytic subunit of PI3K (p110) was achieved from lysates of co-transfected S2 cells as well as RBL-2H3 mast cells stably expressing isc-p85alpha. This indicates that the iscFv part of isc-p85alpha does not negatively influence p85alpha folding and interaction with p110. Moreover, successful incorporation of the p85alpha-moiety of isc-p85alpha into endogenous protein complexes in mast cells suggests the use of isc-containing fusion proteins for the native purification, elution, and analysis of intracellular signaling complexes. 相似文献