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   625篇
  免费   113篇
  国内免费   4篇
耳鼻咽喉   1篇
儿科学   41篇
妇产科学   11篇
基础医学   83篇
口腔科学   31篇
临床医学   115篇
内科学   179篇
皮肤病学   14篇
神经病学   24篇
特种医学   37篇
外科学   24篇
综合类   15篇
预防医学   43篇
眼科学   10篇
药学   24篇
肿瘤学   90篇
  2024年   2篇
  2023年   11篇
  2021年   8篇
  2020年   6篇
  2019年   4篇
  2018年   17篇
  2017年   11篇
  2016年   10篇
  2015年   14篇
  2014年   22篇
  2013年   31篇
  2012年   9篇
  2011年   17篇
  2010年   27篇
  2009年   38篇
  2008年   24篇
  2007年   20篇
  2006年   19篇
  2005年   26篇
  2004年   17篇
  2003年   13篇
  2002年   14篇
  2001年   12篇
  2000年   11篇
  1999年   26篇
  1998年   27篇
  1997年   41篇
  1996年   41篇
  1995年   29篇
  1994年   22篇
  1993年   19篇
  1992年   10篇
  1991年   6篇
  1990年   12篇
  1989年   16篇
  1988年   10篇
  1987年   10篇
  1986年   20篇
  1985年   15篇
  1984年   9篇
  1983年   8篇
  1982年   10篇
  1981年   6篇
  1980年   10篇
  1979年   1篇
  1978年   4篇
  1977年   3篇
  1976年   4篇
排序方式: 共有742条查询结果,搜索用时 15 毫秒
91.
92.
The frequency and pattern of T gamma gene rearrangement and expression was investigated in hematopoietic neoplasms including T and B lymphoid and myeloid malignancies. 39 of 39 T lymphoid neoplasms, including fresh cases and cell lines, were found to display clonal T gamma gene rearrangements. There was heterogeneity with respect to utilization of the two T gamma constant region genes, T gamma C1 and T gamma C2. In 31 cases (80%) T gamma C1 was deleted and T gamma C2 was rearranged, while in the remaining 8 cases (20%) T gamma C1 was rearranged. T gamma gene rearrangements were found in non-T cells, but were restricted to 6/17 (35%) immature B cell neoplasms. All 24 mature B cell and 14 myeloid neoplasms retained the T gamma germ line pattern. T gamma mRNA was found in all T cells tested. However, the majority (16/17) of T cells most likely do not express a T gamma protein since a T alpha/beta heterodimer detected by reactivity with the MoAb WT31 is present on the cell surface together with T3. These data suggest that T gamma gene rearrangements are universal in T cells and frequent in immature B cell neoplastic populations. However, expression of the T gamma protein is extremely infrequent, indicating that T cell neoplasms are very rarely derived from the recently identified T3+T gamma +T alpha/beta- peripheral T cell population.  相似文献   
93.
94.
Ultrasonically guided punctures. A modified technique   总被引:2,自引:0,他引:2  
Lindgren  PG 《Radiology》1980,137(1):235
  相似文献   
95.
This paper describes a qualitative research study which explored the practices and views of nurses working on a new Mental Health Intensive Care Unit A review of the literature identified the main aspects of intensive care provision (1) physical security, (2) characteristics of the patient group, (3) staff-patient ratios, (4) therapeutic environment and (5) multi-agency involvement Twenty-one periods of participant observation helped form the questions for a semi structured in-depth tape recorded interview in which 11 out of a total of 16 trained nurses took part The information is categorized and the discussion is informed by observation of practice The nurses perceived the following as the main issues that the physical environment is inadequate for security, that the patient group appears to have the common characteristic of being unwanted in other clinical settings, that the staff-patient ratio is inadequate and that their vision of the nature of a therapeutic environment is vague  相似文献   
96.
Biologists and physical anthropologists attempted to classify human being into races according to phenotypic variations. The latter are based either on one or two phenotypic characters therefore the outcome is unable to givq clear distinction among different races. Cranial index seems to be an important,tool, which may be used to identify the races in different geographical regions. 75 dried skulls collected from different part of Maharashtra were measured to determine the cranial index. Skulls were classified by the method of Montagu (1960)2 Average maximum cranial length and breadth were found to be 17.11 cm and 12.98 cm respectively and maximum & minimum cranial lengths were observed to be 18.50 and 16.60 cm and cranial breadths were noted to be 14.50 and 12.10 cm respectively. Average cranial index (mean ± SD) was 75.49 ± 3.95. In our study most of the skulls were grouped under the Mesocranial (46.66%) and Dolichocranial (42.66%) categorises when based on Montagu and Dolichocranial categorises when 56% based Comas'. As per the conclusion Maharashtrian population belongs to Indo-Dravidian race.  相似文献   
97.
Oral Diseases (2010) 17 , 90–94 Objective: To evaluate the periodontal status of mucous membrane pemphigoid (MMP) patients and compare it with that of healthy controls. Methods: A prospective study was undertaken to examine the impact of gingival MMP lesions on the human periodontium of 29 patients. Parameters evaluated included full mouth plaque score (FMPS), full mouth bleeding upon probing scores, probing depths (PD), gingival recession, clinical attachment level (CAL), mobility score, furcation involvement, number of missing teeth and Machtei criteria. Results: All periodontal parameters recorded were increased in cases when compared to controls in univariate statistics. The mean differences between groups in PD (0.8 ± 0.2 mm, 95% CI 0.3–1.3), CAL (1.3 ± 0.4 mm, 95% CI 0.4–2.2), FMPS (41.0 ± 6.2%, 95% CI 28.7–53.4), FMBS (16.2 ± 6.6%, 95% CI 3.0–29.4) and tooth loss (2 ± 1 teeth, 95% CI 1–3) were all statistically significant (P < 0.01 for all). Substantial differences in domiciliary oral hygiene routines were observed (P < 0.0001). In multivariate models when FMPS was included as covariate the difference between groups in all clinical periodontal parameters was no longer statistically significant. Conclusions: Our results showed that periodontal status is worse in MMP patients if compared with healthy controls due to a substantial difference in oral hygiene. Oral health should be promoted in MMP.  相似文献   
98.
99.
We have characterized the biocompatibility of nanostructured TiO2 films produced by the deposition of a supersonic beam of TiOx clusters. Physical analysis shows that these films possess, at the nanoscale, a granularity and porosity mimicking those of typical extracellular matrix structures and adsorption properties that could allow surface functionalization with different macromolecules such as DNA, proteins, and peptides. To explore the biocompatibility of this novel nanostructured surface, different cancer and primary cells were analyzed in terms of morphological appearance (by bright field microscopy and immunofluorescence) and growth properties, with the aim to evaluate cluster-assembled TiO2 films as substrates for cell-based and tissue-based applications. Our results strongly suggest that this new biomaterial supports normal growth and adhesion of primary and cancer cells with no need for coating with ECM proteins; we thus propose this new material as an optimal substrate for different applications in cell-based assays, biosensors or microfabricated medical devices.  相似文献   
100.
Aging is accompanied by poor learning and memory abilities and by decreased hippocampal neurogenesis, a process that is also modulated by oxidative stress (OS). P66Shc has recently emerged as a novel mammalian gerontogene able to affect healthspan during aging. Deletion of this gene in mice leads to reduced OS accompanied by decreased incidence of age‐related pathologies and reduced signs of behavioral aging. We hypothesized that p66Shc?/? mutants might show increased neurogenesis in the hippocampus, a brain region involved in learning and memory processes. To this aim, granule cell number, proliferation, neuronal differentiation, and cell death were assessed in the hippocampus in senescent p66Shc?/? [knock out (KO)] and p66Shc+/+ [wild type (WT)] male and female mice. Spatial learning abilities and spontaneous activity were also investigated in a multifunctional behavioral system—IntelliCages. The behavioral analysis revealed that females in general perform better in spatial learning tasks, with genotype effects being apparent in the activity pattern only. Likewise, all females showed increased neuronal differentiation, whereas increased proliferation was found only in those belonging to the p66Shc?/? genotype, indicating that they might be protected from precursor cell loss. The number of dying cells was not affected by genotype or sex; however, all KO mice showed less granule cells than WT. Overall, our data suggest that hippocampal function is protected in the female gender at older age, an effect amplified by reduced OS in the p66Shc?/? mutant. © 2012 Wiley Periodicals, Inc.  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