全文获取类型
收费全文 | 1371篇 |
免费 | 98篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 15篇 |
儿科学 | 121篇 |
妇产科学 | 65篇 |
基础医学 | 195篇 |
口腔科学 | 31篇 |
临床医学 | 74篇 |
内科学 | 267篇 |
皮肤病学 | 46篇 |
神经病学 | 47篇 |
特种医学 | 7篇 |
外国民族医学 | 1篇 |
外科学 | 142篇 |
综合类 | 26篇 |
预防医学 | 72篇 |
眼科学 | 152篇 |
药学 | 117篇 |
中国医学 | 14篇 |
肿瘤学 | 81篇 |
出版年
2024年 | 1篇 |
2023年 | 13篇 |
2022年 | 35篇 |
2021年 | 52篇 |
2020年 | 34篇 |
2019年 | 40篇 |
2018年 | 55篇 |
2017年 | 28篇 |
2016年 | 52篇 |
2015年 | 53篇 |
2014年 | 52篇 |
2013年 | 86篇 |
2012年 | 104篇 |
2011年 | 125篇 |
2010年 | 86篇 |
2009年 | 46篇 |
2008年 | 59篇 |
2007年 | 91篇 |
2006年 | 66篇 |
2005年 | 75篇 |
2004年 | 66篇 |
2003年 | 65篇 |
2002年 | 56篇 |
2001年 | 9篇 |
2000年 | 13篇 |
1999年 | 14篇 |
1998年 | 8篇 |
1997年 | 7篇 |
1996年 | 6篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 9篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 10篇 |
1989年 | 3篇 |
1988年 | 9篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1970年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有1473条查询结果,搜索用时 15 毫秒
71.
The electrophysiological correlates of changes in sensory function during menstrual cycle has already been studied and attributed to the hormonal influence. Effects of estrogen and progesterone on waves of auditory brainstem responses (ABR) have been reported and a hypothesis has been proposed that sex steroids have more influence on central auditory pathways. As mid-latency responses (MLRs) and slow vertex responses (SVRs) are better indicators of central auditory pathways, so MLRs and SVRs were also recorded besides ABRs in the present study. Waves of ABRs, MLRs & SVRs were recorded in 20 normal cycling females in 4 different phases of menstrual cycles from Cz-A1 and Cz-A2 position with alternating 90dB sound pressure click stimuli. Contralateral ear was masked with a white noise of -40 dBHL. With the same setting by changing the number of click stimuli, intervals of stimuli and filter bandpass the above 3 recordings were taken. The evoked responses in females having ovulatory cycles were compared within the four phases using ANOVA test. There is a trend of increase in peak latencies of ABR waves III and V and IPL I-V in estrogen-peak midcycle while decrease in latencies in progesterone-peak (interpeak latency) midluteal phase. Peak latencies of MLR waves No, Po, Na, Pa and Pb also show a same trend. SVR waves P2 and N2 are significantly delayed in mid-cycle (178.80 +/- 20.49, 276.65 +/- 18.32) while conduction is faster in midluteal phase (166.45 +/- 17.41, 261.95 +/- 21.07). Smallest latencies of all the waves are occurring during menstruation. These findings are suggesting that normal cyclical variations in the levels of estrogen and progesterone during menstrual cycle do affect the auditory pathways and effects are better seen on the central component. 相似文献
72.
Dong S Fu PP Shirsat RN Hwang HM Leszczynski J Yu H 《Chemical research in toxicology》2002,15(3):400-407
UVA light-induced DNA single strand cleavage by a set of 12 monomethyl substituted benz[a]anthracenes (MBAs) along with their parent compound, benz[a]anthracene (BA), and the potent carcinogen, 7,12-dimethylbenz[a]anthracene (DMBA), was studied. On the basis of the relative DNA single strand photocleavage efficiency of the fourteen compounds, they are divided into three groups: (1) strong DNA cleavers, 4-MBA, 5-MBA, 6-MBA, 8-MBA, 9-MBA, 10-MBA, and BA; (2) medium DNA cleavers, 1-MBA, 2-MBA, 3-MBA, and 11-MBA; and (3) weak DNA cleavers, 7-MBA, 12-MBA, and DMBA. The relative DNA photocleavage efficiency parallels very well with the energy gap between the highest-occupied-molecular-orbital (HOMO) and the lowest-unoccupied-molecular-orbital (LUMO) of each MBA, indicating that the DNA cleavage is related to their excited-state properties. The 7 and 12 positions of BA are two unique sites. Methyl substitution at either 7 or 12 (or both) positions lowers the HOMO-LUMO gap and greatly diminishes the DNA photocleavage efficiency. UVA light-induced photodegradation of selected MBAs reveals that methyl substitution at either 7 or 12 (or both) positions greatly enhances the degradation rate. Photodegradation of 7-MBA, 12-MBA, and DMBA yields products that are much less effective in mediating DNA cleavage. Photodegradation of other MBAs, exemplified by 5-MBA, yields a photooxidation product 5-MBA-7,12-quinone which is relatively stable under light and is a stronger DNA photocleaver than 5-MBA itself. The higher efficiency of DNA photocleavage for MBAs with methyl substitution at positions other than 7 or 12 is due, at least in part, to the formation of 7,12-quinone. Light-induced DNA single strand cleavage efficiency for several MBAs parallels the light-induced toxicity observed by other research groups, suggesting that light-induced DNA cleavage of MBAs are the source for phototoxicity. Since some PAHs such as coal tar are used commercially as creams, therapeutic agents, or ointments, or those roofers and asphalt workers that are subject to contamination with PAHs, the combination of PAHs and light (in the skin) may present a greater health risk to humans. 相似文献
73.
Dhiman N Bonilla RG Jacobson RM O'Kane D Poland GA 《Scandinavian journal of infectious diseases》2003,35(5):332-336
This is the first study using GeneChip technology to elucidate genetic determinants of the measles vaccine response. A comparative gene expression study was conducted using Affymetrix's Human GeneChip U-95A in 5 human subjects immunized with a 'booster' dose of measles vaccine (Attenuax, Merck) to determine whether serologically distinct subjects exhibit differential expression of human leukocyte antigen (HLA) genes. Healthy individuals aged 15-25 y, previously immunized with 2 doses of measles-mumps-rubella-II (MMR-II) vaccine, were classified as measles vaccine immunoglobulin G-specific antibody seronegatives (n = 2) and seropositives (n = 3). Changes in expression of HLA genes in seronegatives and seropositives were studied on days 7 and 14 post-measles vaccination using Microarray Suite 5.0 (MAS 5.0). There was increased expression of the HLA class I-B (p = 0.0002), HLA class II cluster of DMA, DMB, TAP1, TAP2 (p = 0.0007) and HLA-DR (p = 0.0001) genes, and decreased expression of HLA class I MICB molecule (p = 1), HLA class I-A (p = 0.9999) and major histocompatibility complex class III HSP 70 (p = 0.9999) genes on day 7 or day 14 postvaccination in seropositives compared with seronegatives. These results suggest an association between antibody response and differential HLA gene activation and may explain one potential mechanism underlying measles vaccine non-response. 相似文献
74.
This report describes the clinical findings and outcome of a patient suffering from septic postpartum ovarian vein thrombosis. Treatment modalities are well described and range from hysterectomy and thrombectomy to the use of vena cava filters in combination with anticoagulation and antibiotics. Defervescence with a combination infusion of tissue plasminogen and heparin were used. This treatment approach has been found particularly successful in cases of ilio-femoral, hepatic, renal and vena caval thromboses. 相似文献
75.
Effect of paternal administration of an antiestrogen, tamoxifen on embryo development in rats 总被引:2,自引:0,他引:2
Balasinor N Gill-Sharma MK Parte P D'Souza S Kedia N Juneja HS 《Molecular and cellular endocrinology》2002,190(1-2):159-166
We have earlier reported that oral administration of tamoxifen causes a dose-dependent reduction in the fertility of adult male rats. The decrease in fertility was mainly due to an increase in pre-implantation loss without an effect on fertilizing ability. During the study, an increased incidence of post-implantation loss of conceptuses sired by tamoxifen-treated male rats was observed. A detailed study was undertaken to investigate dose-related changes in pre- and post-implantation loss and the stage(s) of development at which these losses occurred. The present study demonstrates that tamoxifen treatment produced few normal litters as well as significantly increased pre-implantation loss without affecting the rate of fertilization. Also a significant increase in the number of degenerating embryos at the 2–4-cell stage (days 1–2 of gestation), retrieved from the oviduct/uterus of females mated with tamoxifen-treated males was observed. Histology of the resorbed fetuses, in both control and treated groups, showed presence of trophoblast outgrowth indicative of early placenta formation, which normally occurs on days 8–9 of gestation. The present results suggest that pre-implantation loss occurred at the 2–4-cell stage and the post-implantation loss occurred around days 8–9 of gestation, i.e. around midgestation. The possible effects of paternal tamoxifen treatment on embryogenesis may be due to the reduction of androgens or by the blockage of the estrogen receptor by tamoxifen, thereby affecting germ cell maturation during spermatogenesis. 相似文献
76.
B L Dhananjaya A Nataraju R Rajesh C D Raghavendra Gowda B K Sharath B S Vishwanath Cletus J M D'Souza 《Toxicon》2006,48(4):411-421
The snake venom proteins affect hemostasis by either advancing/delaying blood coagulation. Apart from proteases and phospholipase A(2)s (PLA(2)s), 5'nucleotidase is known to affect hemostasis by inhibiting platelet aggregation. In this study, the possible involvement of Naja naja venom 5'nucleotidase in mediating anticoagulant affect is evaluated. Vanillic acid selectively and specifically inhibited 5'nucleotidase activity among other enzymes present in N. naja venom. It is a competitive inhibitor as evident of inhibition relieving upon increased substrate concentration. Vanillic acid dose dependently inhibited the anticoagulant effect of N. naja venom up to 40%. This partial involvement of 5'nucleotidase in mediating anticoagulant effect is substantiated by concanavalin-A (Con-A) inhibition studies. Con-A, competitively inhibited in vitro protease and 5'nucleotidase activity up to 100%. However, it did not exhibit inhibitory activity on PLA(2). The complete inhibition of anticoagulant effect by Con-A upon recalcification time suggests the participation of both 5'nucleotidase and protease in mediating anticoagulant effect of N. naja venom. Vanillic acid and Con-A inhibition studies together suggest that probably 5'nucleotidase interacts with one or more factors of intrinsic pathway of blood coagulation to bring about anticoagulant effect. Thus, this study for the first time demonstrates the involvement of 5'nucleotidase in mediating N. naja venom anticoagulant effect. 相似文献
77.
Neelam Vaid Ajay Kothadiya Subhash Patki Harsh Kanhere 《Indian journal of otolaryngology and head and neck surgery》2002,54(2):143-145
Necrotising fasciitis is a fulminant soft tissue infection that causes necrosis of fascia and subcutaneous tissue while sparing skin and muscle initially. It is most commonly seen in adults involving the perineum, extremities and and minal wall. Immunncompromised patients are at an increased risk of developing this infection. These infections require early diagnosis, aggressive surgical debridaient and appropriate antibiotic therapy. Mortality rates have been reported to be as high as 52 and 73% in general surgery literature.(Freuschtag et al, 1985., Rouse et at 1982). Necrotising fasciitis of the head and neck is rare. The commonest cause is secondary to denial infections. We report a case of necrotising fasciitis of the neck secondary to a peritonsillar abscess in a previously healthy individual. The pathogenesis and treatment of this fulminant infection are also discussed. 相似文献
78.
79.
Haemodialysis activates phospholipase A2 enzyme 总被引:2,自引:1,他引:1
Vishwanath B. S.; Fux C. A.; Uehlinger D. E.; Frey B. M.; Franson R. C.; Frey F. J. 《Nephrology, dialysis, transplantation》1996,11(1):109-116
BACKGROUND: Clinical and experimental evidence suggest that haemodialysis(HD) procedure is an inflammatory process. For the productionof proinflammatory lipid mediators in many inflammatory reactions,the release of arachidonic acid by phospholipase A2 (PLA2 enzymeis a prerequisite. Therefore, the purpose of the present investigationwas to establish whether the activity of PLA2 increases duringHD and whether the increase depends on the type of dialyserused. METHODS: We performed dialysis in eight chronic HD patients. Blood samplesentering and leaving the dialyser were obtained before and at15, 60, 120 and 180 min after the dialysis was started, on oneoccasion using a cuprophane and on another occasion a cellulosetriacetate dialyser. PLA2 activity was assessed in crude plasmaand in plasma extract. RESULTS: PLA2 activity in plasma extract exhibited similar biochemicalproperties to that of inflammatory human synovial fluid PLA2enzyme which is of group II PLA2. PLA2 activity in crude plasmarepresents a type of PLA2 other than the synovial type. In HDpatients, baseline PLA2 activities in crude plasma and plasmaextract were significantly increased when compared to normalsubjects. An increase in PLA2 activity was observed in crudeplasma with a peak appearing at 15 min when the patients weredialysed with cuprophane and cellulose triacetate membranes.This increase was observed in both arterial and venous bloodsamples and was more pronounced when the patients were dialysedwith cuprophane than with cellulose triacetate membranes. WhenPLA2 was assessed in plasma extract, the activity increasedonly with cuprophane but not with cellulose triacetate membranes. CONCLUSIONS: PLA2 activity in plasma is increased in HD patients and increasesduring the dialysis procedure to a greater extent with a lessbiocompatible membrane. Continuous activation of PLA2 mightbe relevant for long-term deleterious consequences of HD. 相似文献
80.
Neelam Bagga Gulzar Singh Chhina Velayudhan Mohan Kumar Baldev Singh 《Brain research》1981,216(2):444-448
Bilateral hippocampal (HPC) stimulation with anodal direct current on the afternoon of proestrus blocked sponstaneous ovulation in 87.5% of the Wistar rats subjected to the experiments. The incidence of the ovulation block by this procedure was reduced to 16.7% on bilateral injection of 0.25 μg picrotoxin into the medial preoptic area (mPOA) preceding as well as following the stimulation. Ovulation was also blocked in 53.8% of the animals by bilateral injection of 50.0 μg GABA into mPOA, while only 20.0% animals showed a blockade of ovulation of HPC stimulation can be simulated mPOA. These observations indicate that blockade of ovulation by saline injection into by local injection of GABA into mPOA while the effect of stimulation can be blocked by local injection of picrotoxin. Thus, indicating the possibility of GABA being neurotransmitter involved at the level of mPOA for mediating the inhibitory hippocampal influence on ovulation. 相似文献