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   13497篇
  免费   682篇
  国内免费   56篇
耳鼻咽喉   134篇
儿科学   225篇
妇产科学   195篇
基础医学   2017篇
口腔科学   533篇
临床医学   940篇
内科学   3179篇
皮肤病学   205篇
神经病学   1001篇
特种医学   702篇
外科学   2146篇
综合类   65篇
预防医学   462篇
眼科学   242篇
药学   756篇
中国医学   9篇
肿瘤学   1424篇
  2023年   61篇
  2022年   129篇
  2021年   232篇
  2020年   115篇
  2019年   135篇
  2018年   241篇
  2017年   182篇
  2016年   225篇
  2015年   214篇
  2014年   254篇
  2013年   316篇
  2012年   575篇
  2011年   645篇
  2010年   318篇
  2009年   305篇
  2008年   565篇
  2007年   575篇
  2006年   619篇
  2005年   614篇
  2004年   596篇
  2003年   622篇
  2002年   698篇
  2001年   440篇
  2000年   474篇
  1999年   486篇
  1998年   210篇
  1997年   175篇
  1996年   148篇
  1995年   118篇
  1994年   129篇
  1993年   137篇
  1992年   341篇
  1991年   337篇
  1990年   289篇
  1989年   290篇
  1988年   300篇
  1987年   261篇
  1986年   240篇
  1985年   216篇
  1984年   168篇
  1983年   108篇
  1982年   66篇
  1981年   61篇
  1979年   128篇
  1978年   78篇
  1977年   68篇
  1976年   70篇
  1975年   74篇
  1974年   66篇
  1973年   65篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
The polyhedrin gene inBombyx morinucleopolyhedrovirus (BmNPV) was replaced with the granulin gene ofTrichoplusia nigranulovirus (TnGV). The substitution was verified by Southern hybridization, and expression of granulin by the mutant virus, BmGran, was demonstrated by sodium dodecyl sulfate–polyacrylamide gel electrophoresis and by amino acid sequencing of the predominant protein of BmGran inclusion bodies (IBs). Light and electron microscopy examination of BmGran-infectedB. moriand BmN cells revealed large, cuboidal, polyhedron-like IBs in the nucleus and cytoplasm, but granules were not seen. IBs contained small, parallel, electron-dense streaks, which defined the geometric pattern of crystallization. Geometric patterns of nuclear IBs were frequently disrupted by occlusion of polyhedron envelope fragments, resulting in IB instability and fracturing. Virions were not embedded in most of the polyhedron-like IBs, but accumulated with polyhedron envelope fragments. Some virions were coated with matrix protein and were partially wrapped by polyhedron envelope. These results suggested that (1) the amino acid sequence of granulin is insufficient for determining IB morphology in TnGV-infected cells, and TnGV may have genes, not present in BmNPV, that control granule formation, and (2) interactions among the virion, the IB envelope, and the matrix protein may be important in virion occlusion and IB morphology and stability.  相似文献   
92.
Clinical application to ascertain the effects of aspoxicillin (ASPC), a new semisynthetic penicillin antibiotic, upon several infectious diseases of children was performed in 7 cases with pneumonia, 5 cases with acute bronchitis, each case with tonsillitis, enterocolitis, urinary tract infection and suspected sepsis. ASPC was injected by drip infusion and the dosage was 63-117 mg/kg/day in 3 and 4 times a day. Clinical efficacy obtained as "excellent" was in 7 cases, "good" in 8 cases "poor" in 1 case, and efficacy rate was 93.8%. From the bacteriological point of view, eliminated in each of H. influenzae, H. parainfluenzae, group A beta-Streptococcus and unchanged in a case of E. coli. There were transient thrombocytopenia in 2 cases and eosinophilia in 3 cases.  相似文献   
93.
Osteopenia/osteoporosis and sarcopenia are common geriatric diseases among older adults and harm activities of daily living (ADL) and quality of life (QOL). Osteosarcopenia is a unique syndrome that is a concomitant of both osteopenia/osteoporosis and sarcopenia. This review aimed to summarize the related factors and clinical outcomes of osteosarcopenia to facilitate understanding, evaluation, prevention, treatment, and further research on osteosarcopenia. We searched the literature to include meta-analyses, reviews, and clinical trials. The prevalence of osteosarcopenia among community-dwelling older adults is significantly higher in female (up to 64.3%) compared to male (8–11%). Osteosarcopenia is a risk factor for death, fractures, and falls based on longitudinal studies. However, the associations between osteosarcopenia and many other factors have been derived based on cross-sectional studies, so the causal relationship is not clear. Few studies of osteosarcopenia in hospitals have been conducted. Osteosarcopenia is a new concept and has not yet been fully researched its relationship to clinical outcomes. Longitudinal studies and high-quality interventional studies are warranted in the future.  相似文献   
94.
Cultivated T24 cells derived from a human bladder cancer were inoculated into the chorioallantoic membrane vein of chick embryos. Hyperthermic treatment was performed following injection of anticancer agents 3 days after the inoculation of the T24 cells. DNA samples were obtained from the livers of the chick embryos, and the polymerase chain reaction technique was used to amplify a DNA fragment specific to the human -globin gene. The Southern hybridization method was used to evaluate the inhibitory effects of anticancer agents in combination with/without hyperthermia on T24 cells metastasized to the liver. The hyperthermia exerted an inhibitory effect on the growth of the T24 cells in the livers of the chick embryos, and this was dependent on the thermal dose. The antitumor effects of hyperthermia performed at 42.5° C for 20 min and at 43.0° C for 10 min were evidenced by 69.2% an 82.0% inhibition of the growth of the metastasized T24 cells, respectively, as compared with the growth of untreated T24 cell. Hyperthermia performed at 42.5° C for 10 min alone produced 26.7% tumor growth inhibition, and these conditions for hyperthermia were subsequently used as a criterion for evaluating the effects of its combination with various anticancer agents. Adriamycin (20 g/egg) alone, mitomycin C (10 g/egg) alone, carboplatin (10 g/egg) alone, and cisplatin (10 g/egg) alone produced 13.5%, 58.9%, 27.3%, and 29.1% tumor growth inhibition, respectively. Adriamycin and mitomycin C applied in combination with hyperthermia showed additive inhibitory effects on the growth of the metastasized T24 cells in this chick embryo model.  相似文献   
95.
Reactive oxygen species in NMDA receptor-mediated glutamate neurotoxicity   总被引:1,自引:0,他引:1  
In search of endogenous protective substances that inhibit neurotoxic action of glutamate and nitric oxide (NO), we found that brain-derived neurotrophic factor (BDNF), acting on TrkB receptor tyrosine kinase, inhibited neurotoxicity induced by glutamate and NO donors in cultured cortical neurons. In co-cultures of the mesencephalon and striatum, projection of mesencephalic dopamine neurons to the striatum attenuated N-methyl-d-aspartate (NMDA)-induced cytotoxicity in dopamine neurons themselves. Growth factors such as neurotrophins, which the target cells in the striatum would synthesize and secrete, may offer the protection of dopamine neurons against glutamate neurotoxicity.  相似文献   
96.
Placement of stents for the tracheal or carinal stenosis have a meaning of maintaining the airway. Failure of the stenting causes death. In cases of severe airway stenosis and low pulmonary function, the pulmonary support method should be performed instead of intubation and mechanical ventilation. Generally, PCPS (percutaneous cardio-pulmonary support system) is used as a pulmonary support. This method was very useful to place stents for airway stenosis. We concluded that PCPS was useful in emergency cases, and in cases of severe fixed type airway stenosis and low pulmonary function it had be on stand-by.  相似文献   
97.
Vasogenic edema on MELAS: a serial study with diffusion-weighted MR imaging   总被引:10,自引:0,他引:10  
The authors performed a serial study of a patient with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like syndrome (MELAS) who presented with diffusion-weighted MRI (DWI). DWI demonstrated a higher apparent diffusion coefficient in the lesion than in the control region during the acute stage of stroke. Vasogenic edema is present in stroke-like episodes in MELAS.  相似文献   
98.
We examined cytosolic cytochrome c in gerbil hippocampal CA1 and CA3 regions after induction of 5-min ischemia by immunoblotting. In the CA1 region, cytochrome c was detected in the cytosolic fraction from 1 to 6 h after ischemia by Western blotting, while it was not detected in the CA3 region. Following intraventricular administration of cyclosporin A (CsA), detectable cytosolic cytochrome c was dramatically decreased, and about 80% of CA1 neurons survived after ischemia. The present studies demonstrate that cytochrome c is translocated from mitochondria to the cytosol in the early stage of delayed neuronal cell death, and suggest the involvement of the mitochondrial permeability transition.  相似文献   
99.
Activated microglial cells and peripheral macrophages are hardly distinguishable from the viewpoints of morphology and function. There are various immunological markers common to both microglial cells and peripheral macrophages. In the present study, however, we found that microglial cells have distinct characters in terms of adhesion and morphology. By using a "rheoscope," that is an apparatus to rheologically measure the strength of cell adhesion to substrates, rat microglial cells were found to attach to polystyrene dishes much more weakly than alveolar and peritoneal macrophages. Interferon-gamma (IFNgamma) strengthened the adhesion of alveolar and peritoneal macrophages, whereas it weakened that of microglial cells. Morphological changes of microglial cells induced by IFNgamma were also different from those of peripheral macrophages. Furthermore, alveolar and peritoneal macrophages produced NO in response to IFNgamma, while microglial cells did not. When cultured on astrocyte-derived extracellular matrix (AsECM) in serum-free medium, only microglial cells extended multiple ramified processes. Conversely, alveolar and peritoneal macrophages on AsECM shrunk their ruffling membrane and rounded up. These distinctions between microglial cells and macrophages may reflect differences in cell lineages as well as environments in which individual cells reside.  相似文献   
100.
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