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   1525篇
  免费   49篇
  国内免费   11篇
耳鼻咽喉   14篇
儿科学   26篇
妇产科学   96篇
基础医学   186篇
口腔科学   15篇
临床医学   101篇
内科学   545篇
皮肤病学   14篇
神经病学   97篇
特种医学   33篇
外科学   129篇
综合类   11篇
预防医学   63篇
眼科学   22篇
药学   148篇
肿瘤学   85篇
  2023年   7篇
  2022年   73篇
  2021年   116篇
  2020年   28篇
  2019年   41篇
  2018年   54篇
  2017年   35篇
  2016年   33篇
  2015年   39篇
  2014年   36篇
  2013年   80篇
  2012年   126篇
  2011年   124篇
  2010年   63篇
  2009年   55篇
  2008年   102篇
  2007年   99篇
  2006年   93篇
  2005年   92篇
  2004年   77篇
  2003年   83篇
  2002年   64篇
  2001年   8篇
  2000年   5篇
  1999年   3篇
  1998年   11篇
  1997年   4篇
  1996年   4篇
  1995年   2篇
  1994年   3篇
  1993年   3篇
  1992年   7篇
  1991年   3篇
  1990年   1篇
  1988年   2篇
  1987年   1篇
  1986年   1篇
  1980年   1篇
  1975年   1篇
  1912年   2篇
  1908年   1篇
  1906年   1篇
  1904年   1篇
排序方式: 共有1585条查询结果,搜索用时 15 毫秒
81.
OBJECTIVES: In the blood serum from women divided into 4 groups (healthy women aged 24 and 45 years and patients after the gynaecological surgery with sparing or radical resection of uterus) the lipids index (WL) was determined. MATERIAL AND METHODS: The WL index expresses the correlations among the HDL, LDL, triglycerides and A1 and B apolipoproteins. In the perimenopausal period in women the decrease in the lipids index WL was observed comparing to the women at age of 25. RESULTS: During the diseases indicated the necessity of gynecological surgery in women in the perimenopausal period further decrease in the lipids index WL was noticed. Contrary to the sparing operation, surgical intervention with radical resection of uterus causes the following WL decrease observed in 3rd month after it. CONCLUSION: It may suggest that these differences have hormonal background.  相似文献   
82.
Most of antidepressants induce expression of the gene coding for brain-derived neurotrophic factor (BDNF) in the hippocampal/cortical neurons. Recent data indicate antidepressant-like activity of zinc in animal models. We now report that chronic treatment with zinc induced an increase in cortical but not hippocampal BDNF mRNA level (Northern blot). Tranylcypromine, a classic antidepressant, increased BDNF mRNA level in both examined brain regions. This is the first demonstration that zinc increases the BDNF gene expression, which is the effect shared by most of clinically effective antidepressants.  相似文献   
83.
In recent years, many new recombinant protein therapeutics have been developed and tested in clinical trials [1]. Current and future clinical uses of recombinant human thyroid-stimulating hormone (rhTSH; Thyrogen, Genzyme) in thyroid diseases are discussed in the review published in this issue of Expert Opinion on Pharmacotherapy [2]. As Thyrogen is a wild-type rhTSH produced in Chinese hamster ovary cells, it has relatively low affinity to the human TSH receptor. Such low affinity and weak intrinsic bioactivity of rhTSH, compared to the bovine or rodent TSH, may help to explain the results of several studies indicating limited clinical efficacy of Thyrogen. TSH analogues with largely increased receptor affinity, potency and efficacy, are expected to provide not only more effective than currently used diagnostic methods, but should also serve as indispensable second-generation thyrotropins for the diagnosis and treatment of thyroid carcinomas with a largely limited number of TSH receptors.  相似文献   
84.
BACKGROUND: Peridural fibrosis developing after lumbar discectomy may be responsible for as much as 20% of all Failed Back Surgery Syndrome. A variety of biological and non-biological materials have been used as a barrier to invasion of fibrous tissue into the vertebral canal. AIM: The purpose of this study was to evaluate the use of expanded polytetrafluoroethylene (ePTFE) surgical membrane (Gore-Tex membrane) to inhibit peridural fibrosis and reduce FBSS symptoms after lumbar discectomy. MATERIAL AND METHODS: In a prospective study we compared postoperative results in 20 patients who had an ePTFE membrane implanted during lumbar discectomy with the results in 20 patients in whom no material was implanted. The outcomes were evaluated using a questionnaire on activities of daily living according to the Low Back Outcome Score, pain grading scale -- Visual Analog Scale, assessment of Lasegue sign and MRI 18-24 months after the operation for all patients. RESULTS: The authors found no evident positive clinical and radiological effects of using ePTFE surgical membrane during lumbar discectomy. CONCLUSIONS: 1. It is impossible to prove that ePTFE membrane used during lumbar discectomy essentially prevents postoperative peridural scar formation. 2. The use of ePTFE membrane does not improve the outcome of the surgical treatment of lumbar disc herniation.  相似文献   
85.
Recent reports have shown that spontaneous spinal cord herniation in the thoracic segment of the spine may be one of the causes of the progressive spinal cord lesion. Although it was described for the first time by Wortzman in 1974, it was only in early 1990s that a growing number of publications on single cases of the condition started to be observed. In the relevant literature collected by us we found reports on 53 patients altogether. In a number of cases herniation was diagnosed only intraoperatively in spite of complex radiological diagnostics. The analysis of relevant literature shows that spontaneous or idiopathic spinal cord herniation has a very typical clinical picture and most cases share a number of features, such as the clinical condition, age and sex of the patient as well as the level and location of the entity and its radiological picture. We conclude that spontaneous herniation of the spinal cord may be not as rare as previously thought and that it should be always taken into account in differential diagnostics of progressive myelopathy in the thoracic segment in middle-aged patients, especially females.  相似文献   
86.
Lack of standardization of methods and detection limits contributes to the controversial results regarding microchimerism after organ transplantation and has prompted the development of a standardized, reproducible, "easy-to-use" flow cytometric method for this type of "rare event analysis".EDTA-blood of healthy, HLA-typed donors was stained simultaneously with FITC- and biotin-labeled HLA-class I antibodies (One Lambda) as well as Cy5-PE-labeled CD45 (Medac, Hamburg) according to a standard protocol and analysed on a Coulter EPICS XL Flow cytometer (FCM).An absolute range of positivity (mean MESF+/- 1 STD) was determined for 22 HLA-specific antibodies. The range of positivity ranged between 5000 and 20,000 MESF (anti-A23, 24(9) FITC) and 40,000-140,000 (anti-Bw6 FITC). The frequency of nonspecific positive signals using nonstained cells, isotype-controls and irrelevant HLA antibodies was between 0.01% and about 0.5%, in some samples up to 1.4%, with an MESF between 8000 and 150,000, thus interfering clearly with the defined positive range of most antibodies tested. Using an "HLA antibody cocktail", combining FITC- and PE-labeled antibodies for different HLA specificities and thereby creating an internal control, the identification of donor cells was improved but was only rarely applicable.Due to the lack of highly reactive antibodies, FCM analysis was not suitable for the reliable identification of very low numbers of donor hematopoetic cells despite the theoretical advantages of flow cytometric detection of rare events. The single parameter approach was hampered by a significant frequency of nonspecific positive signals, which were easily mistaken as specific (true) positive signals, whereas the multiparameter approach could only be used in selected cases.  相似文献   
87.
A flexible approach to response surface modeling for the study of the joint action of three active anticancer agents is used to model a complex pattern of synergism, additivity and antagonism in an in vitro cell growth assay. The method for determining a useful nonlinear response surface model depends upon a series of steps using appropriate scaling of drug concentrations and effects, raw data modeling, and hierarchical parameter modeling. The method is applied to a very large in vitro study of the combined effect of Trimetrexate (TMQ), LY309887 (LY), and Tomudex (TDX) on inhibition of cancer cell growth. The base model employed for modeling dose-response effect is the four parameter Hill equation [1]. In the hierarchical aspect of the final model, the base Hill model is treated as a function of the total amount of the three drug mixture and the Hill parameters, background B, dose for 50% effect D50, and slope m, are understood as functions of the three drug fractions. The parameters are modeled using the canonical mixture polynomials from the mixture experiment methodologies introduced by Scheff [2]. We label the model generated a Nonlinear Mixture Amount model with control observations, or zero amounts, an "NLMAZ" model. This modeling paradigm provides for the first time an effective statistical approach to modeling complex patterns of local synergism, additivity, and antagonism in the same data set, the possibility of including additional experimental components beyond those in the mixture, and the capability of modeling three or more drugs.  相似文献   
88.
The pigment melanin, which is believed to play a photoprotective role, was quantified here in human RPE cells from donors of different age. Electron spin resonance (ESR) spectroscopy was shown to provide a quantitative measure of melanin and was used as a non-destructive measure of melanin content. Results indicated an age-related melanin loss in RPE cells, with melanin content diminishing 2.5-fold between the first and the ninth decade of life. To determine whether photo-oxidation may contribute to age-related changes in RPE melanin, RPE in human eyecups, isolated human and bovine RPE cells, purified melanin granules, or synthetic dopa melanin were irradiated with various wavelengths and intensities of visible light. Samples were analysed for changes in melanin content by ESR spectroscopy, and by absorption and emission spectrophotometry. The concentration of hydrogen peroxide was measured in some samples, and some human eyecups were examined by transmission electron microscopy. Irradiation of RPE in eyecups with intense visible light was found to produce a time-dependent photobleaching of melanosomes that was accompanied by the formation of hydrogen peroxide. Photobleaching of isolated RPE melanosomes and synthetic dopa melanin resulted in enhanced melanin fluorescence, as previously shown for melanin from aged donors by others, and significantly reduced ESR signal intensity, resembling the changes in melanin with aging observed here. We conclude that the content of melanin in RPE cells undergoes an age-related change to which photo-oxidation may contribute. This observation raises the question of whether age-related changes in melanin reduce the photoprotective role of the pigment in aging RPE cells.  相似文献   
89.
PURPOSE: The aim of study is the presentation and retrospective analysis of our experience in implantations of posterior chamber lenses with transcleral fixation. MATERIAL AND METHODS: 172 eyes were analysed after implantations of posterior chamber lenses with transcleral fixation. We analysed operative technique, complications and results. RESULTS: 127 eyes obtained usable visual acuity. CONCLUSIONS: On the basis of our own observations we can say, that implantations of posterior chamber lenses with transcleral fixation is an effective and safe method in lens surgery.  相似文献   
90.
Kosatka M  Rekas M 《Klinika oczna》2003,105(1-2):73-75
The authors described general clinical signs and pathology in eye examination in three patients with Terson syndrome. From this group only one patient recovered. In this case the early eye fundus examination allowed doctors to make the proper diagnosis and led to neurosurgical intervention, just in time.  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