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   2299篇
  免费   149篇
  国内免费   8篇
耳鼻咽喉   15篇
儿科学   88篇
妇产科学   119篇
基础医学   336篇
口腔科学   102篇
临床医学   235篇
内科学   440篇
皮肤病学   40篇
神经病学   332篇
特种医学   126篇
外科学   165篇
综合类   13篇
预防医学   117篇
眼科学   9篇
药学   212篇
中国医学   1篇
肿瘤学   106篇
  2023年   13篇
  2022年   28篇
  2021年   51篇
  2020年   22篇
  2019年   32篇
  2018年   55篇
  2017年   40篇
  2016年   38篇
  2015年   43篇
  2014年   64篇
  2013年   68篇
  2012年   137篇
  2011年   119篇
  2010年   63篇
  2009年   57篇
  2008年   100篇
  2007年   90篇
  2006年   95篇
  2005年   91篇
  2004年   86篇
  2003年   76篇
  2002年   93篇
  2001年   60篇
  2000年   78篇
  1999年   71篇
  1998年   27篇
  1997年   20篇
  1996年   24篇
  1995年   22篇
  1994年   21篇
  1993年   17篇
  1992年   69篇
  1991年   69篇
  1990年   54篇
  1989年   50篇
  1988年   42篇
  1987年   32篇
  1986年   29篇
  1985年   29篇
  1984年   17篇
  1983年   17篇
  1982年   22篇
  1981年   17篇
  1979年   14篇
  1978年   19篇
  1975年   15篇
  1974年   16篇
  1973年   15篇
  1967年   12篇
  1966年   11篇
排序方式: 共有2456条查询结果,搜索用时 15 毫秒
101.
Alpha2 macroglobulin and the risk of Alzheimer's disease   总被引:8,自引:0,他引:8  
BACKGROUND: alpha2 Macroglobulin is a panproteinase inhibitor that is found immunohistochemically in neuritic plaques, a requisite neuropathologic feature of AD. Recently, a pentanucleotide deletion near the 5' end of the "bait region" of the alpha2 macroglobulin (A2M) gene was reported to be associated with AD in a large cohort of sibpairs, in which the mutation conferred a similar odds ratio with AD as the APOE-epsilon4 allele for carriers of at least one copy of the A2M gene (Mantel-Haenszel odds ratio, 3.56). METHODS: We studied three independent association samples of AD patients (n = 309) with an age range of 50 to 94 years and representative controls (n = 281) to characterize the allele frequency of the pentanucleotide deletion in this cohort. We detected the mutation near the 5' splice site of exon 18 using standard PCR and restriction fragment length polymorphism methods. The results were adjusted for age, gender, education, and APOE polymorphism. RESULTS: We found that the A2M gene polymorphism conferred an increased risk for AD, with an estimated Mantel-Haenszel ratio of 1.5 (95% CI 1.1 to 2.2; p = 0.025). There was no age- or gender-dependent increase in A2M gene allele frequencies in AD patients compared with controls. The combined sample showed the expected association between AD and APOE-epsilon 4. In one of our three samples there was an interaction between the A2M and APOE-epsilon4 genes, but the other two samples showed no interaction between the two risk factors. CONCLUSIONS: Our data support an association between the A2M gene and AD. This association is less pronounced, however, in our cohort than in the previously reported sample of sibpairs.  相似文献   
102.
Esophageal intramural pseudodiverticulosis is a very rare disease of unclear etiology. The clinical picture is characterized by progressive dysphagia. Because of its frequent association with alcohol abuse and subsequent weight loss, it must be differentiated reliably from esophageal carcinoma. The diagnosis is established by the characteristic detection of multiple intramural contrast accumulations in the barium esophagogram. Additional endoscopic and endosonographic confirmation and histological examination are required to exclude a malignant tumor. Moreover, associated diseases are almost always present and should also be diagnosed by pH-metry, cytology, and esophageal manometry. Good and long-lasting therapeutic success can be achieved by bouginage of the stenosis with concomitant treatment of the associated esophageal diseases. Based on two case reports of patients with this disease, we discuss the unusual association with esophageal hypermotility as well as the symptoms, clinical course, therapy, and pathogenesis of the disease.  相似文献   
103.
104.
Diagnosis of premature rupture of amniotic membranes in premature pregnancy allows to estimate dangers which threaten foetus and pregnant woman and helps to put into practice the most accurate therapeutics procedures. The aim of this study was to prove the clinical usefulness of test detecting insulin-like growth factor binding protein-1 in vaginal secretion for diagnose of premature rupture of amniotic membranes and compare the sensiviteness and specificity the above test with Gram stained vaginal smears. We examined group of 50 pregnant women between 25 and 42 week of pregnancy treated in Department of Fertility and Obstetrics Medical University of Wroc?aw. Pregnant women were divided into 3 groups. In each of them both tests were performed to diagnose premature rupture of amniotic membranes. Achieved scores shows that Amni Check is specific and sensitive test detecting even insignificant premature rupture of amniotic membranes and has higher sensitivity comparing with common method used until now for detection of premature rupture of amniotic membranes based on Gramm stained vaginal secretion.  相似文献   
105.
106.
Using electroencephalographic sleep data from a sample of 235 elderly subjects, discriminant function analyses of sleep alterations in depression and dementia were performed. Overall, 80% of patients were correctly classified using a backward discriminant function analysis, and 81% with a general stepwise discriminant function analysis. Four measures contributed to the separation of depressed and demented patients: rapid eye movement (REM) sleep latency (lower in depressives); REM sleep percent (higher in depressives); indeterminate non-REM sleep percent (higher in demented patients, reflecting greater loss of spindles and K complexes); and early morning awakening (more marked in depressives). When both discriminant functions were subjected to cross-validation in independent subsamples, both procedures correctly identified 78% of patients. The classification functions derived from nondemented depressed and nondepressed demented patients were applied to a mixed-symptom group (n = 42). Overall, 27 patients (64%) with either depressive pseudodementia or dementia with depressive features were correctly classified using the same four predictor variables. These findings suggest that sleep physiological alterations of depression and dementia reflect between-group differences in sleep continuity, sleep architecture, and REM sleep temporal distribution, and that the differences are statistically reliable, in both diagnostically pure and mixed clinical presentations. These findings are discussed in the context of current hypotheses of sleep regulation and its mechanisms.  相似文献   
107.
Lactation is an immunologically unique state when immune factors are produced by the mother for the protection of the infant rather than the mother. While several studies have focused on the immunological composition of human milk, much less information is available on maternal immune status during lactation. Sixty-four lactating and 43 bottlefeeding women at 1–2 weeks, 1, 2, 4 or 8 months post-partum were studied in a cross-sectional design, with 14 nulliparous women as controls. Flow cytometry analysis of peripheral blood lymphocytes showed dynamic, post-partum changes in the B-cell subpopulation. Among lactating women, the relative percents of CD19+ B-cells were significantly lower (P < 0.05) than control levels at 1–2 weeks and 1 month post-partum, but showed a significant, polynomial-linear rise (P < 0.05) over time, reaching control values by 2–4 months post-partum. Bottle-feeding women had an earlier rise in the percentage of CD 19 + cells, with relative percents always significantly higher than their lactating counterparts. The differing patterns may be due to changes in serum prolactin concentrations because, among the post-partum women, relative percents of CD19+ cells were negatively correlated with baseline serum prolactin concentrations. These results have implications for maternal immunization programs designed to enhance maternal and/or infant well-being as well as other maternal health effects related to breastfeeding.  相似文献   
108.
109.
Greenberg VL  Zimmer SG 《Oncogene》2005,24(30):4851-4860
Initial chemotherapeutic treatment triggers a stress-related response, which can lead to an increase in the expression of survival proteins. In this study we examine whether paclitaxel (PTX) alters the expression and/or phosphorylation of the translation initiation proteins, eukaryotic initiation factor 4E (eIF-4E) and 4E-binding protein (4E-BP1), a suppressor of eIF-4E in the dephosphorylated state. We found that PTX induced the hyperphosphorylation of 4E-BP1 in the breast cancer cell line, MDA MB 231, which reduced its association with eIF-4E, but did not alter the expression and phosphorylation of eIF-4E. The hyperphosphorylation of 4E-BP1 correlated with G2/M accumulation and with an increase in the phosphorylation of cdk1 substrates. Cotreatment with a histone deacetylase inhibitor (an indirect inhibitor of cdk activity), purvalanol A and roscovitine (direct cdk inhibitors), and the reduction of cyclin B expression using RNA interference decreased the hyperphosphorylation of 4E-BP1 in PTX treated cells. The hyperphosphorylation of 4E-BP1 by PTX increased the association of eIF-4E with eIF-4G, whereas cotreatment with purvalanol A inhibited the association of eIF-4E with eIF-4G in PTX treated cells. Taken together, our data suggest that PTX-increases the functional level of eIF-4E by promoting the hyperphosphorylation and release of 4E-BP1 through a cdk1-dependent mechanism.  相似文献   
110.
Aphidicolin, a tetracyclic diterpene antibiotic produced by Cephalosporium aphidicola, is under investigation as anti-cancer drug. Because of its poor solubility in water, it cannot be administered directly in vivo. Systemic application of aphidicolin glycinate or aphidicolin gamma-cyclodextrin complexes resulted in tumour growth inhibition but not in cures. To improve the pharmacokinetics, a liposomal preparation of aphidicolin was developed and tested in neuroblastoma-bearing (UKF-NB-3) mice. The loading capacity of these liposomes was limited. Therefore, 4.5 mg aphidicolin/kg body weight was the maximum aphidicolin dose that could be applied as liposomal preparation in this approach. Comparison of effects on tumour growth exhibited by aphidicolin liposomes (4.5 mg aphidicolin/kg) given for 15 consecutive days to those of gamma-cyclodextrin inclusion complexes (15 mg aphidicolin/kg) revealed comparable tumour growth inhibition, although aphidicolin concentrations were approximately 3-fold lower. This shows that liposomal encapsulation is a promising strategy for the improvement of systemic anti-cancer activity of aphidicolin.  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