全文获取类型
收费全文 | 9875篇 |
免费 | 712篇 |
国内免费 | 125篇 |
专业分类
耳鼻咽喉 | 205篇 |
儿科学 | 343篇 |
妇产科学 | 249篇 |
基础医学 | 1229篇 |
口腔科学 | 237篇 |
临床医学 | 1010篇 |
内科学 | 2050篇 |
皮肤病学 | 93篇 |
神经病学 | 940篇 |
特种医学 | 591篇 |
外国民族医学 | 3篇 |
外科学 | 1404篇 |
综合类 | 198篇 |
一般理论 | 6篇 |
预防医学 | 855篇 |
眼科学 | 150篇 |
药学 | 598篇 |
2篇 | |
中国医学 | 9篇 |
肿瘤学 | 540篇 |
出版年
2021年 | 115篇 |
2020年 | 81篇 |
2019年 | 130篇 |
2018年 | 134篇 |
2017年 | 89篇 |
2016年 | 115篇 |
2015年 | 165篇 |
2014年 | 193篇 |
2013年 | 274篇 |
2012年 | 371篇 |
2011年 | 445篇 |
2010年 | 294篇 |
2009年 | 267篇 |
2008年 | 383篇 |
2007年 | 446篇 |
2006年 | 358篇 |
2005年 | 407篇 |
2004年 | 347篇 |
2003年 | 342篇 |
2002年 | 345篇 |
2001年 | 298篇 |
2000年 | 297篇 |
1999年 | 251篇 |
1998年 | 177篇 |
1997年 | 176篇 |
1996年 | 174篇 |
1995年 | 148篇 |
1994年 | 127篇 |
1993年 | 141篇 |
1992年 | 218篇 |
1991年 | 238篇 |
1990年 | 226篇 |
1989年 | 228篇 |
1988年 | 205篇 |
1987年 | 222篇 |
1986年 | 205篇 |
1985年 | 207篇 |
1984年 | 142篇 |
1983年 | 122篇 |
1982年 | 99篇 |
1980年 | 99篇 |
1979年 | 137篇 |
1978年 | 108篇 |
1977年 | 84篇 |
1976年 | 104篇 |
1975年 | 97篇 |
1974年 | 79篇 |
1973年 | 76篇 |
1972年 | 90篇 |
1971年 | 75篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Nichols KE Haines K Myung PS Newbrough S Myers E Jumaa H Shedlock DJ Shen H Koretzky GA 《Journal of leukocyte biology》2004,75(3):541-552
The Src-homology 2 domain-containing, leukocyte-specific phosphoprotein of 76 kDa (SLP-76) is a hematopoietic adaptor that plays a central role during immunoreceptor-mediated activation of T lymphocytes and mast cells and collagen receptor-induced activation of platelets. Despite similar levels of expression in macrophages, SLP-76 is not required for Fc receptor for immunoglobulin G (IgG; FcgammaR)-mediated activation. We hypothesized that the related adaptor SLP-65, which is also expressed in macrophages, may compensate for the loss of SLP-76 during FcgammaR-mediated signaling and functional events. To address this hypothesis, we examined bone marrow-derived macrophages (BMM) from wild-type (WT) mice or mice lacking both of these adaptors. Contrary to our expectations, SLP-76(-/-) SLP-65(-/-) BMM demonstrated normal FcgammaR-mediated activation, including internalization of Ig-coated sheep red blood cells and production of reactive oxygen intermediates. FcgammaR-induced biochemical events were normal in SLP-76(-/-) SLP-65(-/-) BMM, including phosphorylation of phospholipase C and the extracellular signaling-regulated kinases 1 and 2. To determine whether macrophages functioned normally in vivo, we infected WT and SLP-76(-/-) SLP-65(-/-) mice with sublethal doses of Listeria monocytogenes (LM), a bacterium against which the initial host defense is provided by activated macrophages. WT and SLP-76(-/-) SLP-65(-/-) mice survived acute, low-dose infection and showed no difference in the number of liver or spleen LM colony-forming units, a measure of the total body burden of this organism. Taken together, these data suggest that neither SLP-76 nor SLP-65 is required during FcgammaR-dependent signaling and functional events in macrophages. 相似文献
72.
新生期大白鼠皮下注射谷氨酸单钠对成年后下丘脑α-促黑素细胞激素神经元免疫反应性的影响 总被引:2,自引:0,他引:2
本文用免疫组化方法研究了新生期大白鼠注射谷氨酸单钠(MSG)对成年后下丘脑α-促黑素细胞激素(α-MSH)免疫反应神经元的影响,结果显示MSG处理以后下丘脑弓状核区α-MSII免疫反应神经元减少甚至完全消失,但不影响下丘脑背外侧区的α-MSH神经元群。文中还讨论了这两群α-MSH神经元的生理作用。 相似文献
73.
Systematic changes in gene expression in postmortem human brains associated with tissue pH and terminal medical conditions 总被引:8,自引:0,他引:8
74.
75.
The authors investigated factors that predict intention to take a genetic test for Alzheimer's disease (AD). The 449 men and women were surveyed in two groups: (a) those told that a positive result meant a 90% chance of developing AD (increased certainty) and (b) those told that a positive result meant a 50% chance of developing AD (decreased certainty). Participants completed measures of the Theory of Planned Behavior (TPB), anticipated regret, risk perception, likelihood of taking a genetic test for cancer, and AD risk factors. Just over 50% of the variance in intentions was related to TPB variables, likelihood of taking a genetic test for cancer, number of people the participants knew who had AD, experimental condition, and anticipated regret. The subjective norm was the strongest predictor of intention in the increased certainty group, whereas positive belief was the strongest predictor in the decreased certainty group. 相似文献
76.
The numerical density of senile plaques (SP) and neurofibrillary tangles (NFT) as revealed by the Glees silver method was compared with SP and NFT revealed by the Gallyas method and with amyloid (A4) deposits in immunostained sections in 6 elderly cases of Alzheimer's disease. The density of NFT was generally greater and A4 lower in tissue from hippocampus compared with the neocortex suggesting that A4 deposition was less important than the degree of paired helical filament (PHF) related damage in the hippocampus. The density of Glees SP was positively correlated Gallyas SP weakly correlated with A4 deposit number. A stepwise multiple regression analysis which included A4 deposit and Gallyas SP density and accounted for 54% of the variation in Glees SP density. Hence, different populations of SP were revealed by the different staining methods. The results suggested that the Glees method may stain a population of SP in a region of cortex where both amyloid deposition and neurofibrillary changes have occurred. 相似文献
77.
78.
The rate at which the acute phase protein response occurred after both major and minor surgery was explored. Increases in the plasma concentration of C-reactive protein (CRP), alpha-1-acid glycoprotein (alpha 1 AG) and fibrinogen were not detected until 6-8 h after the initial incision. The peak concentration of CRP occurred at 48 h and that of fibrinogen at 96 h; alpha 1 AG concentrations rose rapidly until 48 h followed by little change until about 120 h. Although there was widespread variation in the concentrations of individual proteins in patients, severity of injury did not seem to have a significant effect on the time course of the change. Plasma cortisol concentration and the total white blood cell count (WBC) reached their peaks before the acute phase proteins, cortisol at 6 h and WBC at 12 h. 相似文献
79.
In the freely moving rat, the kinetics of Ca2+ ion activity were determined at circumscribed sites in the hippocampus, which was perfused with ethanol, tertiary-butyl alcohol or acetaldehyde. Initially, a region in CA1 or other cell field of the dorsal hippocampus was prelabelled by microinjection of45Ca2+ through a permanently implanted guide tube. Then the tip of a concentric push-pull cannula assembly was lowered through the guide tube to the labelled site, and an isotonic artificial cerebrospinal fluid was repeatedly perfused at a rate of 25 μ1/min. Each perfusion was timed for 5.0min with a 5.0 min interval between each. Once the washout curve of45Ca2+ activity had begun to approach its asymptote, ordinarily in the midpoint of a series of perfusions, an isotonic solution of ethanol (188–942 mM), tertiary-butyl alcohol (12–580 mM) or acetaldehyde (10–98 mM) was added to the fourth perfusate. Thereafter, the hippocampal site was again perfused with the normal cerebrospinal fluid for the remainder of the experiment. Although the lowest concentration of ethanol exerted no effect on45Ca2+ ion activity, an intermediate concentration caused mixed effects in either enhancing or suppressing the efflux into the perfusate of this cation. The highest concentration of ethanol produced in most experiments an initial suppression in Ca2+ ion efflux which was followed frequently by an elevation in the release of45Ca2+. Similar changes in Ca2+ ion activity were produced by tertiary-butyl alcohol, but the magnitude of its effect was generally less than that of ethanol, suggesting that its effect on brain tissue differs from that of ethanol. Acetaldehyde evoked an intense and concentration-dependent enhancement of Ca2+ ion efflux from the perfused tissue at all of the sites in the hippocampus examined.These results suggest that in the unrestrained rat ethanol could unbind Ca2+ ions from hippocampal membranes or retard their uptake into cells of the hippocampus. The dual excitatory and inhibitory effect of ethanol on Ca2+ ion activity corresponds to the electrophysiological effects of this alcohol and could alter neurotransmitter release from neurons in this subcortical structure. The mechanism of action of acetaldehyde is envisaged to be due to its affinity to membrane sulfhydryl groups which alters protein conformation and thus interferes with both Ca2+channels and Ca2+ binding properties. 相似文献
80.
Considerations in using linkage analysis as a presymptomatic test for Huntington''s disease. 总被引:2,自引:0,他引:2 下载免费PDF全文
The polymorphic locus D4S10 that is genetically linked to the locus for Huntington's disease (HD) has made possible a presymptomatic test for those at risk. Because the symptoms of this progressively debilitating and fatal illness are not usually manifest until adulthood, the outcome of the test will influence major decisions about career, marriage, and procreation. Several differential diagnoses must be considered before using the test if HD is not confirmed in at least one family member. Review of a large number of pedigrees has shown that 40% of persons at risk do not have appropriate family structure for a linkage test. Furthermore, uncooperative or inaccessible relatives may make this test infeasible for many others who wish to be tested. Linkage phase, which must be known in the affected parent for an informative test, can be determined using one or more of 12 probe-enzyme combinations for D4S10. Although the polymorphism information content (PIC) value for any one RFLP is less than 40%, the PIC value for the haplotype of the two G8 HindIII, pK083 EcoRI, and R7 BglII RFLPs is greater than 88%. We have developed a scheme to incorporate linkage data and age at onset information adjusted for censored observations, sex of affected parent, and familial correlation for age at onset, using the computer program MLINK for calculation of risk of having HD. Simulated experiments showed that proper age at onset adjustment is crucial to the calculation of the probability of risk. A formal presymptomatic testing protocol, including pre- and post-test counselling, psychological testing, and paternity testing is recommended. Many of these considerations are illustrated in several actual test cases. 相似文献