全文获取类型
收费全文 | 5467篇 |
免费 | 451篇 |
国内免费 | 13篇 |
专业分类
耳鼻咽喉 | 112篇 |
儿科学 | 222篇 |
妇产科学 | 102篇 |
基础医学 | 697篇 |
口腔科学 | 123篇 |
临床医学 | 539篇 |
内科学 | 1063篇 |
皮肤病学 | 70篇 |
神经病学 | 404篇 |
特种医学 | 408篇 |
外国民族医学 | 1篇 |
外科学 | 811篇 |
综合类 | 134篇 |
一般理论 | 2篇 |
预防医学 | 441篇 |
眼科学 | 56篇 |
药学 | 495篇 |
中国医学 | 1篇 |
肿瘤学 | 250篇 |
出版年
2021年 | 59篇 |
2020年 | 41篇 |
2019年 | 65篇 |
2018年 | 101篇 |
2017年 | 80篇 |
2016年 | 101篇 |
2015年 | 99篇 |
2014年 | 149篇 |
2013年 | 183篇 |
2012年 | 272篇 |
2011年 | 256篇 |
2010年 | 170篇 |
2009年 | 187篇 |
2008年 | 252篇 |
2007年 | 267篇 |
2006年 | 230篇 |
2005年 | 216篇 |
2004年 | 180篇 |
2003年 | 165篇 |
2002年 | 177篇 |
2001年 | 152篇 |
2000年 | 168篇 |
1999年 | 128篇 |
1998年 | 92篇 |
1997年 | 93篇 |
1996年 | 91篇 |
1995年 | 76篇 |
1994年 | 71篇 |
1993年 | 79篇 |
1992年 | 103篇 |
1991年 | 94篇 |
1990年 | 76篇 |
1989年 | 118篇 |
1988年 | 107篇 |
1987年 | 127篇 |
1986年 | 106篇 |
1985年 | 91篇 |
1984年 | 61篇 |
1983年 | 67篇 |
1982年 | 48篇 |
1981年 | 45篇 |
1980年 | 60篇 |
1979年 | 54篇 |
1978年 | 51篇 |
1977年 | 48篇 |
1976年 | 38篇 |
1975年 | 57篇 |
1974年 | 39篇 |
1973年 | 37篇 |
1970年 | 36篇 |
排序方式: 共有5931条查询结果,搜索用时 15 毫秒
41.
A cDNA for the estradiol-regulated 24K protein: Control of mRNA levels in MCF-7 cells 总被引:1,自引:0,他引:1
Ines Moretti-Rojas Suzanne A. W. Fuqua Robert A. Montgomery III William L. McGuire 《Breast cancer research and treatment》1988,11(2):155-163
We have previously demonstrated an estradiol-regulated 24 kDa (24K) protein in human breast cancer tissue culture cells and human tumor biopsies. The presence of 24K correlates well with the presence of steroid hormone receptors. In order to further study the hormonal regulation of the 24K protein and gene, we have isolated cDNA clones corresponding to the 24K mRNA.Poly(A)+ RNA isolated from the MCF-7 human breast cancer cell line was translated in a cell-free translation system containing [35S]-methionine. The translation products were immunoprecipitated with a 24K monoclonal antibody, and thein vitro synthesis of 24K protein was confirmed by sodium dodecylsulfate (SDS) polyacrylamide gel electrophoresis. The same poly(A)+ RNA was used to construct an oligo(dT)-primed cDNA library in thegt11 expression vector system. The library was screened with a highly specific polyclonal antibody raised against 24K protein purified by immunoaffinity chromatography. Four recombinant clones reacting with the antibody by virtue of antigen expression were isolated and three were used in hybridization-selected translation. Three clones were able to hybridize specifically to a messenger RNA (mRNA) that yielded a Mr 24,000 protein when translatedin vitro and analyzed by SDS/polyacrylamide gel electrophoresis. This protein was also immunoprecipitable by the 24K monoclonal antibody. MCF-7 mRNA size fractionated by formaldehyde-agarose gel electrophoresis was transferred to nitrocellulose paper and hybridized to a nick-translated 24K cDNA clone. A single band of hybridization corresponding to a mRNA size of approximately 0.9–1.0 kilobase (kb) was observed. Using this same technique, 24K cDNA was hybridized to mRNA extracted from MCF-7 cells that had been treated for varying periods with either estradiol, nafoxidine, or tamoxifen. The 24K mRNA was elevated by the addition of estradiol, and clearly diminished by nafoxidine and tamoxifen.These results demonstrate that we have isolated cDNA clones for the study of the hormonal regulation of the 24K gene in breast cancer cells, and have shown that the mRNA is regulated by estradiol. 相似文献
42.
8-Hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT) has been reported to increase food intake. This effect was confirmed in rats consuming plain or sweetened wet mash. However, the consumption of a 35% sucrose solution or of a range of other flavoured liquids was enhanced marginally if at all by a single low dose of 8-OH-DPAT, and the drug actually decreased the consumption of a high protein liquid diet. 8-OH-DPAT did, however, increase gnawing on a wooden block. These results suggest that 8-OH-DPAT-induced hyperphagia may to some extent be secondary to the elicitation of chewing behaviour. 8-OH-DPAT also caused certain other behavioural changes, including a suppression of grooming. 相似文献
43.
Montgomery LC Douglass LW Deuster PA 《The Journal of orthopaedic and sports physical therapy》1989,10(8):315-322
Funding for this study was provided by the U.S. Army Medical Research and Development Command, Project No. 85PP5866, under the Joint Working Group on Drug Dependent Degradation in Military Performance Program. The opinions or assertions contained herein are private ones of the authors and are not to be construed as official or reflecting the views of the Department of Defense or the Uniformed Services University of the Health Sciences. The reliability of an isokinetic test of muscle strength and endurance was evaluated. Eleven males and 9 females underwent testing on three separate occasions, 2-4 days apart. The protocol included a velocity spectrum test (VST-5 repetitions at velocities ranging from 90-330 degrees /sec) and a muscle endurance test (number of contractions performed in 45 sec at 180 degrees /sec). In the VST, no significant within-subject test day differences were noted at any velocity. Reliability was generally higher at slower velocities and higher for knee extension than flexion. Mean intraclass correlation coefficients (ICCs) for peak torque across velocities were 0.88 for extension and 0.79 for flexion. For the endurance test, two reliable measures were total work performed and average power (ICCs = 0.92); relative endurance measures had ICCs of less than 0.80. Thresholds for demonstrating experimental effects and the number of subjects to test at different detection levels are-recommended.J Orthop Sports Phys Ther 1989;10(8):315-322. 相似文献
44.
Montgomery SA 《Journal of psychopharmacology (Oxford, England)》1989,3(2):47-53
Antidepressants are used for long periods of time and until recently there were no formal requirements for establishing efficacy in the maintenance phase or the prophylactic phase of the treatment of depression. The CPMP guidelines advise regulatory authorities in the EEC to consider the efficacy of antidepressants in the medium and the long term separately from efficacy in the treatment of the acute episode. This paper reviews the efficacy of antidepressants in continuation treatment and prophylactic treatment of unipolar depression. Prophylactic studies are difficult and time consuming and it is important to adopt adequate trial methodology. The minimum criteria for the demonstration of prophylactic efficacy are presented. 相似文献
45.
James L Onambele G Woledge R Skelton D Woods D Eleftheriou K Hawe E Humphries SE Haddad F Montgomery H 《European journal of applied physiology》2004,92(1-2):227-230
A reduction in interleukin-6 (IL-6) activity may contribute to the beneficial effects of hormone replacement therapy (HRT) on the menopausal decline in bone mineral density (BMD). We have examined this hypothesis using a genetic strategy. The –174C (rather than G) IL-6 gene variant is associated with lower IL-6 expression. As such, we might anticipate the C allele to be associated with a greater response to HRT. We have tested this hypothesis. Mean three-site [spine (L1-L4), neck of femur, and Wards triangle] BMD was measured in 65 women in a 1-year randomised controlled trial of HRT with 0.625 mg oestrogen/day and 0.15 mg norgestrel (n=30). Baseline BMD was genotype-independent for both the control and HRT group. In the control group, the percentage change in BMD after 1 year was similar between genotypes (P=0.45). In contrast, in the HRT group, the rise was genotype-dependent. Those homozygous for the G allele showed a 3.62 (2.14)% increase in BMD compared with 10.44 (4.68)% for the C-homozygous group. Heterozygotes had an intermediate BMD increase of 5.6 (2.82)% [P=0.006 (P value for interaction between HRT and genotype was 0.04)] Although the study was limited by its small sample size, these are the first data to demonstrate the importance of IL-6 genotype in determining response to oestrogen therapy, rather than its physiological withdrawal. 相似文献
46.
Hormonal fluctuations associated with the menstrual cycle influence
appetite control and eating behaviour. Energy intake varies during the
reproductive cycle in humans and animals, with a periovulatory nadir and a
luteal phase peak. Patterns of macronutrient selection show less
consistency but a number of studies report carbohydrate cravings in the
premenstrual phase, particularly in women with premenstrual syndrome. The
cyclical nature of food cravings are frequently, but not invariably,
associated with depression. Fluctuations in appetite, cravings and energy
intake during the menstrual cycle may occur in parallel with cyclical
rhythms in serotonin, which can be accompanied by affective symptoms. The
premenstrual phase can be considered as a time when women are especially
vulnerable to overconsumption, food craving and depression; this is often
associated with low serotonin activity.
相似文献
47.
Background
Intimate partner violence (IPV) against women is a global public health problem, yet data on IPV against Native American women are extremely limited. We conducted a cross-sectional study of Native American women to determine prevalence of lifetime and past-year IPV and partner injury; examine IPV in relation to pregnancy; and assess demographic and socioeconomic correlates of past-year IPV.Methods
Participants were recruited from a tribally-operated clinic serving low-income pregnant and childbearing women in southwest Oklahoma. A self-administered survey was completed by 312 Native American women (96% response rate) attending the clinic from June through August 1997. Lifetime and past-year IPV were measured using modified 18-item Conflict Tactics Scales. A socioeconomic index was created based on partner's education, public assistance receipt, and poverty level.Results
More than half (58.7%) of participants reported lifetime physical and/or sexual IPV; 39.1% experienced severe physical IPV; 12.2% reported partner-forced sexual activity; and 40.1% reported lifetime partner-perpetrated injuries. A total of 273 women had a spouse or boyfriend during the previous 12 months (although all participants were Native American, 59.0% of partners were non-Native). Among these women, past-year prevalence was 30.1% for physical and/or sexual IPV; 15.8% for severe physical IPV; 3.3% for forced partner-perpetrated sexual activity; and 16.4% for intimate partner injury. Reported IPV prevalence during pregnancy was 9.3%. Pregnancy was not associated with past-year IPV (odds ratio = 0.9). Past-year IPV prevalence was 42.8% among women scoring low on the socioeconomic index, compared with 10.1% among the reference group. After adjusting for age, relationship status, and household size, low socioeconomic index remained strongly associated with past-year IPV (odds ratio = 5.0; 95% confidence interval: 2.4, 10.7).Conclusions
Native American women in our sample experienced exceptionally high rates of lifetime and past-year IPV. Additionally, within this low-income sample, there was strong evidence of socioeconomic variability in IPV. Further research should determine prevalence of IPV against Native American women from diverse tribes and regions, and examine pathways through which socioeconomic disadvantage may increase their IPV risk.48.
49.
Telfer JF; Thomson AJ; Cameron IT; Greer IA; Norman JE 《Human reproduction (Oxford, England)》1997,12(10):2306-2312
Superoxide, an agent which attenuates the half-life of nitric oxide, is
metabolized and synthesized by superoxide dismutase (SOD) and xanthine
oxidase, respectively. Over the last few years much work has focused on the
role of nitric oxide in human parturition. The aim of this study was to
determine whether the onset of human parturition is associated with a
change in the expression of copper/zinc superoxide dismutase (Cu/Zn SOD),
manganese superoxide dismutase (Mn SOD) or xanthine oxidase within the
uterus. Samples of myometrium, placenta, decidua and fetal membranes were
obtained from women before and after the onset of labour at term.
Immunocytochemistry was used to localize Cu/Zn SOD, Mn SOD and xanthine
oxidase and measure SOD enzyme activity. Cu/Zn and Mn SOD-like
immunoreactivity was detected in syncytiotrophoblast cells, villous stromal
cells and endothelial cells of blood vessels in the placenta. In the
myometrium Cu/Zn and Mn SOD were localized to myocytes and endothelial
cells and to some vascular smooth muscle cells. In the fetal membranes we
observed staining for Cu/Zn SOD and Mn SOD in the amnion, chorion,
extravillous trophoblast and decidua. There was no difference in SOD enzyme
activity or staining intensity for SOD between different cell types before
and during labour. Xanthine oxidase immunoreactivity was identified in each
of the tissues examined and again there was no difference in immunostaining
in tissues obtained from women delivered before or after the onset of
labour. These results show that the pregnant uterus is capable of both
synthesizing and degrading superoxide and suggest that superoxide dismutase
and xanthine oxidase may play a role in the maintenance of uterine
quiescence during pregnancy, but not in the initiation of parturition.
相似文献
50.
Cytostasis of different tumours by a murine PPD-reactive CD4+ T lymphocyte clone is mediated by interferon-gamma and tumour necrosis factor alone or synergistically. 总被引:1,自引:3,他引:1 下载免费PDF全文
M G Wing A M Montgomery C Harley P J Lachmann 《Clinical and experimental immunology》1990,82(2):208-213
We have shown that a murine CD4+ PPD-reactive T lymphocyte clone was weakly cytotoxic towards the syngeneic tumour B16 melanoma and MC6A fibrosarcoma which had been coated with PPD using a monoclonal antibody-PPD heteroconjugate. Cell-free supernatants produced by PPD-stimulated T lymphocyte clones were however highly cytostatic for the two tumour targets when assayed over 48-72 h. In this study we have demonstrated good titres of tumour necrosis factor (TNF) and interferon-gamma (IFN-gamma) in the supernatants, which accounted for their observed cytostatic activity on the tumour targets. The high level of cytostasis seen with the B16 melanoma using the supernatants could be attributed to their sensitivity to the cytostatic activity of IFN-gamma; the lower levels of cytostasis seen with the IFN-gamma-resistant MC6A target was the result of IFN-gamma increasing the sensitivity of this target to TNF. Antibodies to IFN-gamma were able to neutralize the majority of the cytostatic activity of the supernatants on both targets, consistent with the role demonstrated for this lymphokine. 相似文献