首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1094篇
  免费   124篇
  国内免费   10篇
耳鼻咽喉   7篇
儿科学   18篇
妇产科学   120篇
基础医学   203篇
口腔科学   10篇
临床医学   109篇
内科学   203篇
皮肤病学   28篇
神经病学   53篇
特种医学   119篇
外科学   94篇
综合类   6篇
现状与发展   1篇
预防医学   93篇
眼科学   28篇
药学   48篇
肿瘤学   88篇
  2023年   25篇
  2022年   9篇
  2021年   17篇
  2020年   24篇
  2019年   17篇
  2018年   26篇
  2017年   27篇
  2016年   30篇
  2015年   25篇
  2014年   39篇
  2013年   44篇
  2012年   32篇
  2011年   43篇
  2010年   45篇
  2009年   40篇
  2008年   44篇
  2007年   55篇
  2006年   49篇
  2005年   44篇
  2004年   42篇
  2003年   31篇
  2002年   39篇
  2001年   28篇
  2000年   33篇
  1999年   42篇
  1998年   22篇
  1997年   11篇
  1996年   7篇
  1995年   12篇
  1994年   23篇
  1993年   11篇
  1992年   18篇
  1991年   11篇
  1990年   21篇
  1989年   29篇
  1988年   21篇
  1987年   16篇
  1986年   13篇
  1985年   16篇
  1984年   16篇
  1983年   10篇
  1982年   9篇
  1981年   8篇
  1980年   9篇
  1979年   9篇
  1978年   9篇
  1976年   9篇
  1975年   7篇
  1969年   9篇
  1968年   7篇
排序方式: 共有1228条查询结果,搜索用时 31 毫秒
71.
Target organs express antigens directly recognized by antigen-specific T cells, thereby precipitating rejection. When early T-cell activation is inhibited, there is a low risk of rejection. We sought to determine the predictive values of serial posttransplant blood cyclosporine trough (C(0)) concentrations to minimize the risk for a first rejection episode compared with 2-hour postdose (C(2)) drug concentrations. The final aim of the study was to identify a concentration range for the best predictive pharmacokinetic parameter that should be targeted to reduce the risk of rejection. This possibility was explored in 334 de novo kidney transplant recipients who participated in the prospective, multicenter Mycophenolate Steroid-Sparing Trial. Among measurements performed during the first 6 months postsurgery, cyclosporine C(0) levels measured early after transplantation were the strongest predictor of acute graft rejection. Levels within 300 to 440 ng/mL were associated with the lowest risk of rejection, while patients with levels lower than 300 ng/mL showed a more than double risk. Cyclosporine trough values predicted allograft rejection with an accuracy of 74%, while C(2) levels had no predictive value. These findings underline the need to target cyclosporine therapy early posttransplant to modulate T-cell activation.  相似文献   
72.
The effect of tri-iodothyronine (T3) and IGL on the intensity of incorporation of L-[14C]tyrosine and on the rate of protein synthesis in the liver mitochondria of thyroidectomized rats and on the radioactivity of the amino-acid pool in the liver was investigated. The intensity of incorporation of L-[14C]tyrosine into proteins in the liver mitochondria of thyroidectomized animals and the rate of protein synthesis in them were found to be only half of their values in animals undergoing mock operations. Administration of T3 or IGL to thyroidectomized rats restored protein synthesis in the liver mitochondria to normal. IGL had a similar effect to T3 on all biochemical indices studied. The absence of thyroid hormones circulating in thyroidectomized animals or administration of T3 or IGL to them did not change the radioactivity of the free tyrosine pool in the liver tissue.Central Biophysical Laboratory, Bulgarian Academy of Sciences, Sofia. (Presented by Academician of the Academy of Medical Sciences of the USSR N. A. Yudaev.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 8, pp. 167–170, August, 1978.  相似文献   
73.
I Dimitrov 《Folia medica》1978,20(1):35-41
The purpose of this article is to determind what effect if any place of birth has upon family size, both actual and ideal, in the Bulgarian city of Plovdiv. It is a retrospective study of 181 families comprised of 2 cohorts, one with couples married for 5 years, the other with couples married for 10 years. The author found that place of origin, whether rural, other towns, Plovdiv itself, or a combination of any two of those, had no significant effect on desired or ideal family size. 79.1% of the women considered the two-child family ideal. When asked to specify an ideal family size in the light of their personal experience, however, 17.8% preferred a single-child family. 18.6% in the 10-year cohort preferred this size and 16.8% in the 5-year cohort. This evidence that individuals retrospectively modify their ideal family size downwards. Those couples in which both partners came from villages had the highest actual family size (1.62). For the total contingent the average number of children was 0.14, smaller than the planned one.  相似文献   
74.

Background  

The objective of this study was to assess the status of oxidative stress in term small for gestational age (SGA) newborn infants born to undernourished mothers by estimating levels of erythrocyte superoxide dismutase (SOD), catalase, reduced glutathione, and serum malondialdehyde (MDA) in cord blood and comparing them to healthy appropriate for gestational age (AGA) controls. This was done in a case control design at a tertiary level teaching hospital.  相似文献   
75.
76.
Literature data on the occurrence of CCND1 alterations in ovarian tumors are insufficient. The objective of this study was to assess the incidence of CCND1 copy number changes in a large number of ovarian tumors and its relation to the tumor phenotype: degree of malignancy, histological type, tumor stage, and grade. Fluorescence in situ hybridization (FISH) for analysis of CCND1 copy number changes was applied on a collection of 1 006 ovarian tumors--468 malignant, 48 with low malignant potency, and 490 benign tumors--arranged in tissue microarray. CCND1 amplification was found in 8.46% of the malignant cases and in 8.11% of those with low malignant potency. It was not found in benign ovarian tumors. CCND1 amplification was associated with the mucinous type of ovarian cancer (p<0.0001). CCND1 genetic gain was revealed in 9.06% of the malignant tumors, in 2.70% of the tumors with low malignant potency, and in 4.87% of the benign ovarian tumors. CCND1 gains and amplifications were not associated with the tumor grade and stage. Our results suggest that CCND1 gains are early events in ovarian tumorogenesis.  相似文献   
77.
OBJECTIVES: To evaluate the characteristics of hypertensive subjects who practise self measurement of blood pressure (SMBP) and their conditions of use, and to identify the properties of subjects using SMBP according the usual guidelines. METHODS: In 531 consecutive hypertensive subjects, referred to hypertension specialists, possessing a SMBP a questionnaire evaluating the condition of use of SMBP was given. Subjects following the guidelines about the use of SMBP have been compared to those using SMBP without specific design of supervision. RESULTS: In this population, aged 62 +/- 14 years, with 57% of men and a mean blood pressure of 147 +/- 23/82 +/- 12 mmHg, the SMBP devices have been bought without medical advice in 50% of cases (265/531). In 45% of cases (239/531), SMBP were made at the wrist. SMBP device was used every days in 26% of cases, every weeks in 27% of cases, every month or more in 22% of cases and only in case of uneasiness in 25% of cases. Blood pressure was measured only in the morning in 25% of cases, in the morning and evening in 31%, only the evening in 8% and at any time of the day in 36% of cases. More frequently 2 BP measurements were realized (47%) and in 19% of cases 3 measurements have been performed. In 15% of cases, the measurements were performed on 3 or 4 days consecutively, more frequently (85%) the measurements were realized without specific design ("once in awhile"). The data of SMBP were noted and showed to the doctor in 34% of cases. Only 12% (64/531) of subjects followed the usual guidelines concerning the use of SMBP (2 or 3 measurements, in the morning and the evening, during 3 or 4 consecutive days). Subjects following the guidelines for SMBP use have a higher SBP at the office than those using SMBP without specific design of supervision (155 +/- 25 mmHg vs 146 +/- 22 mmHg; p<0.01). CONCLUSION: Among hypertensives referred to hypertension specialists most of subjects use SMBP device without a specific design of supervision. Subjects with the most severe hypertension are those who have the best formation for SMBP.  相似文献   
78.
The release of the pituitary hormones, prolactin and growth hormone (GH), and of adrenal corticosteroids is subject to a profound regulation by sleep. In addition these hormones are known to be involved in the regulation of the immune response. Here, we examined their role for in vitro production of T-cell cytokines. Specifically, we hypothesized that increased concentrations of prolactin and GH as well as a decrease in cortisol, i.e., hormonal changes characterizing early nocturnal sleep, could be responsible for a shift towards T helper 1 (Th1) cytokines during this time. Whole blood was sampled from 15 healthy humans in the morning after regular sleep and was activated in vitro with ionomycin and two concentrations of phorbol myrestate acetate (PMA, 8 and 25 ng/ml) in the absence or presence of prolactin, prolactin antibody, GH, glucocorticoid receptor (GR) antagonist RU-486, or mineralocorticoid receptor (MR) antagonist spironolactone. Hormones were examined at physiological concentrations. Production of T-cell derived cytokines was measured at the single cell level using multiparametric flow cytometry. Generally, effects were more pronounced after stimulation with 8 rather than 25 ng/ml PMA. The following changes reached significance (p <.05): prolactin (versus prolactin antibody) increased tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) producing CD4+ and CD8+ cells and interleukin-2 (IL-2) producing CD8+ cells. Compared with control, prolactin antibody decreased, whereas GH increased IFN-gamma+CD4+ cells. RU-486 increased TNF-alpha, IFN-gamma, and IL-2 producing CD4+ and CD8+ cells. Surprisingly strong effects were found after MR blocking with spironolactone which increased TNF-alpha, IFN-gamma, and IL-2 producing CD4+ and CD8+ cells. No effects on IL-4+CD4+ cells were observed, while the IFN-gamma/IL-4 ratio shifted towards Th1 after spironolactone and after RU-486 plus GH. Results suggest that enhanced prolactin and GH concentrations as well as low cortisol levels during early nocturnal sleep synergistically act to enhance Th1 cytokine activity.  相似文献   
79.
The aim of this retrospective study is to find the CS rate, which to maintain the perinatal mortality at a lowest possible level in groups of patients with normal and high risk pregnancies. There were 123598 births for a period from 1976 to 2000 years. The CS rate has increased from 4.8% to 24.5% and the PNM has decreased from 27.7@1000 to 11.4@1000. The statistical analysis shows that the for this period the CS rate is one of the factors to decrease the PNM (r = -0.776, p < 0.05). In the group of pregnancies with normal risk the PMN is between 8 and 11@1000 at the CS rate of 15-16% while in the group with high-risk pregnancies the same PNM is achieved with 24-26% CS rate. The antenatal mortality is not influenced by the CS rate and is almost unchanged for 24 years (r = -0.339, p > 0.05).  相似文献   
80.
The probiotics or biotherapeutical agents are microorganisms that have an antagonistic activity regarding pathogens in vivo. Therapeutic application of these microorganisms is mostly in cases of infections of non-sterile mucous surfaces--vagina and large intestines. With the help of the probiotic L. acidophilus bacterial vaginosis can be treated successfully in a natural way. The lack of systemic side effects makes it a drug of choice in the treatment of pregnant women. More studies in this direction and development of new strategies for treatment of bacterial vaginosis in pregnant and non-pregnant women are needed.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号