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   5185篇
  免费   256篇
  国内免费   25篇
耳鼻咽喉   64篇
儿科学   77篇
妇产科学   58篇
基础医学   582篇
口腔科学   293篇
临床医学   364篇
内科学   1344篇
皮肤病学   80篇
神经病学   302篇
特种医学   216篇
外科学   822篇
综合类   22篇
预防医学   368篇
眼科学   48篇
药学   391篇
中国医学   39篇
肿瘤学   396篇
  2022年   63篇
  2021年   88篇
  2020年   41篇
  2019年   77篇
  2018年   79篇
  2017年   63篇
  2016年   67篇
  2015年   62篇
  2014年   87篇
  2013年   131篇
  2012年   173篇
  2011年   222篇
  2010年   106篇
  2009年   95篇
  2008年   186篇
  2007年   211篇
  2006年   206篇
  2005年   221篇
  2004年   193篇
  2003年   195篇
  2002年   206篇
  2001年   182篇
  2000年   188篇
  1999年   179篇
  1998年   58篇
  1997年   70篇
  1995年   36篇
  1994年   43篇
  1993年   36篇
  1992年   130篇
  1991年   124篇
  1990年   123篇
  1989年   134篇
  1988年   139篇
  1987年   151篇
  1986年   138篇
  1985年   130篇
  1984年   94篇
  1983年   60篇
  1982年   34篇
  1981年   38篇
  1979年   52篇
  1977年   41篇
  1975年   38篇
  1973年   32篇
  1971年   49篇
  1970年   45篇
  1969年   47篇
  1967年   34篇
  1966年   35篇
排序方式: 共有5466条查询结果,搜索用时 46 毫秒
1.
Purpose: To study the prevalence and time of onset of ocular complications in intermediate uveitis (IU) and to assess their effects on visual outcome in short-term and long-term follow-up.

Methods: A retrospective cohort study of patients with IU who had a minimal follow-up of one year.

Results: 96 patients (174 eyes, 70% females) were included with a mean age at presentation of 30 years. Children constituted 38% of all patients. Mean follow- up was 64.9 months. Pars planitis was the most common form followed by sarcoidosis and multiple sclerosis. Cystoid macular edema (CME), cataract, epiretinal membrane and posterior synechiae were the most prevalent complications. Posterior synechiae, band keratopathy, cataract and papillitis at presentation were associated with worse presenting visual acuity (VA). Of the late-onset complications, glaucoma/ocular hypertension (OHT) was the most significantly associated with worse long-term VA. Most sight-threatening complications (namely CME and glaucoma) were diagnosed at presentation while late complications predominantly affected the posterior segment and included among others peripheral retinal elevations, vasoproliferative tumors, and vitreous hemorrhage. Median LogMAR VA improved at short-term and long-term follow-up, from 0.2 to 0.1 (p<0.001). Subgroup analysis revealed significant VA improvement for eyes with all the different complications except for eyes with glaucoma/OHT.

Conclusion: IU is a chronic low-grade uveitis that may be associated with protean early and late complications of the anterior or posterior segments or both. Optimal treatment regimens are imperative for the strict control of inflammation and proper management of complications thus allowing a favorable long-term prognosis.  相似文献   

2.
3.
4.
PURPOSE: To clarify the appropriate concentration and dose of hypertonic saline solution (HSS) for preventing delayed neuronal death in the hippocampal CA1 subfield after transient forebrain ischemia in gerbils. METHODS: Thirty gerbils were randomly assigned to five groups: physiological saline solution (PSS) group, ischemia/reperfusion treated with PSS 2 mL x kg(-1); 5% HSS group, treated with 5% HSS 2 mL x kg(-1); 7.5% HSS group, treated with 7.5% HSS 2 mL x kg(-1); 10% HSS group, treated with 10% HSS 2 mL x kg(-1); 20% HSS group, treated with 20% HSS 2 mL x kg(-1). Transient forebrain ischemia was induced by occluding the bilateral common carotid arteries for four minutes. Five days later, histopathological changes in the hippocampal area were examined, and the degenerative ratio of the pyramidal cells were measured according to the following formula: (number of degenerative pyramidal cells/total number of pyramidal cells per 1 mm of hippocampal CA1 subfield) x 100. RESULTS: In PSS and 20% groups, neuronal cell damage was observed five days after ischemia. In the other three groups, these changes were not observed. The degenerative ratios of pyramidal cells were as follows; PSS group: 91.6 +/- 5.6%, 5% HSS group: 7.2 +/- 1.6%, 7.5% group: 8.3 +/- 1.4%, 10% HSS group: 6.2 +/- 1.1%, 20% HSS group: 85.8 +/- 8.7% (P < 0.05; PSS and 20% HSS vs three other groups). CONCLUSION: This study demonstrates that 5, 7.5 or 10% HSS 2 mL x kg(-1) may prevent delayed neuronal death in the hippocampal CA1 subfield after cerebral ischemia/reperfusion in gerbils.  相似文献   
5.
6.
Kindling of the visual cortex in cats: comparison with amygdaloid kindling   总被引:3,自引:0,他引:3  
Kindling of the primary visual cortex (VC) was compared with that of the amygdala in cats. VC kindling was basically similar to kindling of the amygdala in that daily electrical stimulation can lead to the development of a generalized convulsion in most subjects, a growth of afterdischarges in their configuration and duration, and a reduction of the afterdischarge threshold. The kindling response of the VC differed from that of the amygdala in a number of respects, i.e., a high afterdischarge threshold, a different pattern of behavioral seizure development, an abrupt growth of electroclinical seizures coincident with the onset of a generalized convulsion, an intersubject variability in seizure susceptibility, and a marked seizure instability. In VC kindling the afterdischarge propagation into the amygdala was not observed until the generalized convulsion developed, and the early involvement of afterdischarge was seen in the pulvinar, lateral geniculate body, and superior colliculus. These data suggest that a neural mechanism different from amygdaloid kindling may participate in VC kindling, and that the subcortical structures of the visual system are involved in the preferential pathway for a seizure generalization from the VC.  相似文献   
7.
8.
Two tumor-associated cellular proteins, 82k/6.3 (MW/pI) and 61k/7.5, which were detected by two-dimensional gel electrophoresis, were studied by biochemical and immunological methods. In two-dimensional gel electrophoresis, 82k/6.3 and 61k/7.5 were rich in colon cancer tissue compared with normal colon mucosa, and they were also detected in fetal intestines. This shows that both proteins might be involved in category of oncofetal proteins. The localization of 82k/6.3 and 61k/7.5 was investigated by subcellular fractionation. They were rich in microsomal fraction, but not found in both nuclear and mitochondrial fractions. In binding reaction with seven kinds of lectins, 82k/6.3 reacted with RCAI, DBA and WGA, where 61k/7.5 reacted with RCAI, DBA, WGA, UEAI and SBA. Transferrin reacted with only RCAI. Each hybrid producing monoclonal antibody against 82k/6.3 or 61k/7.5 was generated by fusing spleen cells of BALB/c mice immunized by the two proteins and mouse myeloma cells. Each monoclonal antibody was specified in enzyme-linked immunoassay. In indirect immuno-fluorescent studies, monoclonal antibodies against 82k/6.3 and 61k/7.5 reacted with cytoplasma and membrane of human cancer cells. This result strongly suggests the localization of the two proteins demonstrated by subcellular fractionation.  相似文献   
9.
Background and objectives: The aim of this study was to evaluate the practical value of the dermatoscopic classification of Clark nevi Patients and methods: Dermatoscopic images of 268 lesions clinically and dermatoscopically diagnosed as Clark nevi were presented to 2 dermatologists without knowledge of the histological diagnosis. The dermatologists evaluated the lesions according to a simplified version of the classification scheme for Clark nevi proposed by Hofmann‐Wellenhof and differentiated between 12 different types of Clark nevi. Results: The most common type of Clark nevus was the reticular‐homogenous type (n = 64, 23,9 %), followed by the globular‐homogeneous type (n = 32, 12 %) and by the homogenous type (n = 30, 11,2 %). The overall inter‐rater agreement between the examiners was moderate to good (kappa = 0,58). The highest level of agreement was found for the peripheral hyperpigmented type (kappa = 0,83). Histologically, 17 lesions (6,3 %) were diagnosed as melanomas. The frequency of melanoma was highest among the peripheral‐hyperpigmented type for one observer and among the homogenous type for the other observer. No melanoma was found among the globular, reticular‐globular, and the central‐hyperpigmented types. Conclusions: A dermatoscopic classification of Clark nevi is practically feasible and allows – to some extent – a risk stratification of Clark nevi, which could be useful for clinical management.  相似文献   
10.
We previously selected a group of hypertension candidate genes by a key word search using the OMIM database of NCBI and validated 525 coding single nucleotide polymorphisms (SNPs) in 179 hypertension candidate genes by DNA sequencing in a Japanese population. In the present study, we examined the association between 61 non-synonymous SNPs and blood pressure variations and hypertension. We used DNA samples taken from 1,880 subjects in the Suita study, a population-based study using randomly selected subjects. Analyses of covariance adjusting for age, body mass index, hyperlipidemia, diabetes, smoking, drinking, and antihypertensive medication revealed that 17 polymorphisms in 16 genes (APOB, CAST, CLCNKB, CTNS, GHR, GYS1, HF1, IKBKAP, KCNJ11, LIPC, LPL, P2RY2, PON2, SLC4A1, TRH, VWF) were significantly associated with blood pressure variations. Multivariate logistic regression analysis with adjustment for the same factors revealed that 11 polymorphisms in 11 genes (CAST, CTLA4, F5, GC, GHR, LIPC, PLA2G7, SLC4A1, SLCI8A1, TRH, VWF) showed significant associations with hypertension. Five polymorphisms in five genes, CAST(calpastatin), LIPC (hepatic lipase), SLC4A1 (band 3 anion transporter), TRH (thyrotropin-releasing hormone), and VWF (von Willebrand factor), were significantly associated with both blood pressure variation and hypertension. Thus, our study suggests that these five genes were susceptibility genes for essential hypertension in this Japanese population.  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