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   3794篇
  免费   260篇
  国内免费   31篇
耳鼻咽喉   40篇
儿科学   110篇
妇产科学   111篇
基础医学   571篇
口腔科学   53篇
临床医学   634篇
内科学   616篇
皮肤病学   66篇
神经病学   424篇
特种医学   96篇
外科学   351篇
综合类   54篇
一般理论   6篇
预防医学   405篇
眼科学   60篇
药学   231篇
中国医学   1篇
肿瘤学   256篇
  2023年   28篇
  2022年   38篇
  2021年   75篇
  2020年   66篇
  2019年   80篇
  2018年   81篇
  2017年   59篇
  2016年   94篇
  2015年   88篇
  2014年   103篇
  2013年   170篇
  2012年   244篇
  2011年   249篇
  2010年   155篇
  2009年   140篇
  2008年   216篇
  2007年   243篇
  2006年   223篇
  2005年   253篇
  2004年   201篇
  2003年   255篇
  2002年   196篇
  2001年   44篇
  2000年   24篇
  1999年   43篇
  1998年   48篇
  1997年   44篇
  1996年   23篇
  1995年   36篇
  1994年   29篇
  1993年   30篇
  1992年   21篇
  1990年   15篇
  1989年   14篇
  1988年   18篇
  1987年   17篇
  1986年   21篇
  1985年   22篇
  1984年   21篇
  1983年   19篇
  1982年   29篇
  1981年   27篇
  1980年   27篇
  1979年   25篇
  1978年   20篇
  1977年   18篇
  1976年   25篇
  1975年   13篇
  1974年   14篇
  1970年   12篇
排序方式: 共有4085条查询结果,搜索用时 0 毫秒
21.
Prostaglandin E2 (PGE2), which is generated by the enzymatic activity of cyclooxygenase-1 and -2 (COX-1/2), plays a central role in the maturation process of dendritic cells (DC). Since regulation of COX-1/2 expression in human DC is only partially understood, we addressed the expression and activity of COX-1/2 in these cells. Here we show that lipopolysaccharide (lps) induces COX-2 mRNA and protein synthesis as well as the release of PGE2 in human interleukin-4 and granulocyte/macrophage colony-stimulating factor-differentiated monocyte-derived DC cultivated in the presence of 1% human plasma. Moreover, we found that lps induces p38 stress-activated protein kinase (p38) in these cells and inhibitors of p38 blocked lps-induced COX-2 expression and activity. Our data indicate that during lps-induced maturation p38 regulates COX-2 expression and PGE2 synthesis in DC.  相似文献   
22.
This report describes a spectrum of respiratory symptoms in workers exposed to trimellitic anhydride (TMA), a biologically reactive chemical used in the plastics industry. Fourteen workers who had worked on a unit which synthesized TMA were evaluated by clinical and immunologic methods. Respiratory syndromes induced by TMA inhalation included asthma and rhinitis of the immediate type, late onset asthma with systemic symptoms, and airway irritation. TMA was shown to couple rapidly to human serum albumin, forming an immunoreactive hapten-protein complex. The workers' immunologic reactivity to this complex could be quantitated and correlated with the three respiratory syndromes. The asthma-rhinitis syndrome was mediated by IgE antibody specific for the TMA hapten. The syndrome of late onset asthma with systemic symptoms was accompanied by elevated levels of TMA-specific IgG antibody. Rheumatoid factor in high titer was found in one worker with IgE-mediated asthma and in two workers with asthma of late onset. Lymphocyte reactivity of TMA-HSA was demonstrated in three workers representative of the three clinical syndromes. Leukocyte histamine release was demonstrated to TMA-HSA in one worker with high levels of IgE antibody specific for TMA-HSA who had severe symptoms of acute rhinitis and asthma.  相似文献   
23.
BACKGROUND: Data on the efficacy of pimecrolimus cream 1% within the first days of treatment are scarce, as in previous studies, the first postbaseline assessment was performed only after 1 week. OBJECTIVE: We sought to investigate the onset of action of pimecrolimus cream 1% in infants with mild to very severe atopic eczema. METHODS: We used pimecrolimus cream 1% (n = 129) or vehicle cream (n = 66) administered in a double-blind manner for 4 weeks and then open-label pimecrolimus cream 1% for 12 weeks, with a 4-week follow-up period. RESULTS: Pimecrolimus cream 1% reduced the mean Eczema Area and Severity Index at 4 weeks by 71.5% compared with an increase of 19.4% with vehicle ( P < .001). The reduction in the Eczema Area and Severity Index with pimecrolimus cream 1% was significant at day 4 (38.5% vs 17.6% increase with vehicle). Significant improvements in caregivers' assessments of pruritus and sleep loss were observed with pimecrolimus cream 1% by day 2 ( P < .03) and day 3 ( P = .002), respectively, compared with vehicle. Responses to pimecrolimus cream 1% were sustained during the open-label phase, and pimecrolimus cream 1% was well tolerated. Symptoms of atopic eczema returned gradually after discontinuation. CONCLUSION: Pimecrolimus cream 1% was well tolerated and effective in patients with mild to very severe atopic eczema, with rapid onset of action and no disease rebound after discontinuation.  相似文献   
24.
In the pars distalis of the pituitary gland in adult and embryonic dwarf (dw/dw) mutant mice, ambiguous cells exhibiting ultrastructural features common to growth hormone (GH) cells and prolactin (Prl) cells were analyzed by means of colloidal gold ultrastructural immunocytochemistry in order to define the functional nature of these peculiar cells. Adult and 18-day embryonic pituitaries from normal (+/+; dw/+) and dwarf (dw/dw) mice were processed with antibodies to GH, Prl, TSH (thyroid-stimulating hormone), ACTH (adrenocorticotropic hormone), LH (luteinizing hormone), FSH (follicle-stimulating hormone), and HCG (chorionic gonadotropic hormone). In the adult and embryonic dwarf pituitaries, the ambiguous cells reacted negatively to all of the antibodies except for anti-ACTH, which labeled them well. In addition, the ACTH-positive cells showed a much wider variety of shapes and granule size and distribution, as compared with normal adults. In the embryos, this variability in ACTH cell morphology occurred not only in dwarf embryos, but in their normal counterparts as well. The results thus suggest that adult dwarf pituitaries may retain an embryonic or incompletely differentiated form of ACTH cells. © 1993 Wiley-Liss, Inc.  相似文献   
25.
Autoimmunity may be associated with acute or chronic inflammation. In order to determine whether the inflammatory marker C-reactive protein (CRP) was an indicator of inflammatory events that precede, predict, or associate with islet autoimmunity or type 1 diabetes, CRP was measured in sequential antibody-negative, seroconversion, and follow-up-positive samples from 65 prospectively studied islet autoantibody-positive children. Although changes in CRP concentrations were observed in some children, overall CRP concentrations were similar in antibody-negative samples (median, 0.21 mg/L), antibody-positive samples (median, 0.26 mg/L), and samples at seroconversion (median, 0.26 mg/L). CRP concentrations at diabetes onset (median, 0.59 mg/L) were not significantly increased over antibody-negative samples (P = 0.07). CRP concentrations did not predict diabetes development. CRP concentrations were related to age (r = 0.26; P < 0.001) and were increased in samples obtained from October to January (P < 0.001). These findings suggest that CRP concentrations are not a valuable marker of progression to type 1 diabetes and highlight the importance of correcting analyses for seasonal variations.  相似文献   
26.
Bundesgesundheitsblatt - Gesundheitsforschung - Gesundheitsschutz - Vor dem Hintergrund der derzeitigen COVID-19-Pandemie entstand die Idee zur Durchführung einer Studie, in der die...  相似文献   
27.
Notfall + Rettungsmedizin - Übelkeit und Erbrechen (Nausea und Vomitus, NV) sind geläufige Symptome in der Notfallmedizin, mit etwa 3–4 % der Behandlungsanlässe auf...  相似文献   
28.
BackgroundProtroca evaluated the efficacy and safety of primary and secondary prophylaxis of neutropenia with lipegfilgrastim (Lonquex®) in breast cancer patients receiving neoadjuvant or adjuvant chemotherapy (CT).Patients and MethodsOf the 255 patients enrolled, 248 patients were evaluable for the intent-to-treat (ITT) and 194 patients for the per-protocol set. Primary and secondary end points after lipegfilgrastim treatment were assessed.ResultsNine patients of the ITT set receiving lipegfilgrastim as primary prophylaxis (n = 222) had febrile neutropenia of grade 3–4 (5 patients) or infection of grade 3–4 (4 patients); 1/26 of those receiving secondary prophylaxis had an event. Dose reductions were performed in 9.5% of the patients. Postponement of cancer CT cycles for >3 days occurred in <15% of patients; 10.8% (92/851 AEs) and 8% (2/25 SAEs) of documented adverse events and serious adverse events, respectively, were related to lipegfilgrastim.ConclusionsApplication of lipegfilgrastim was effective as primary and secondary prophylaxis in the prevention of CT-induced neutropenia in breast cancer.  相似文献   
29.
30.
The only effective measure to decrease morbidity and mortality caused by the influenza virus in the human population is worldwide vaccination. Vaccination produces neutralizing antibodies that target the HA1 subunit of the HA (hemagglutinin) protein and are strain specific. The effectiveness of new influenza vaccines are linked to two factors, the correct prediction of the circulating strains in the population in a particular season and the concentration of the HA1 protein in the vaccine formulation. With the advent of the licensing of quadrivalent vaccines, pharmaceutical manufacturers are under considerable pressure due to time constraints and dedicated resources to deliver 194–198 million doses (2020–2021 U.S. market) of vaccine. Considering the valuable resources needed to produce the influenza vaccine in a timely manner, the efficient quantitation of the HA1 protein (the main component in the influenza vaccine) is required. Currently the only method approved by regulatory agencies for quantitation of the HA antigen in vaccines is the single radial immunodiffusion assay (SRID), an antibody dependent assay that is not time efficient. Time efficient methods that are antibody independent e.g. reverse phase-high performance liquid chromatography (RP-HPLC) or size exclusion-HPLC (SE-HPLC) are available. An improved method implementing reverse phase-ultra performance liquid chromatography (RP-UPLC) has been developed to quantitate the HA1 protein antigen present in the high yield reassortant vaccine seed viruses from influenza A H1N1 and H3N2 subtypes harvested from inoculated embryonated chicken eggs. This method differentiates between high yield and lower yielding reassortants in order to select the best vaccine candidate seed virus with the highest growth ‘in ovo’. This direct capability to monitor the HA1 concentration of potential reassortant seed viruses and to choose the best yielding HA influenza reassortant when faced with multiple viral seed candidates provides a major advantage on the industrial scale to the influenza vaccine process.  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