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   134636篇
  免费   5807篇
  国内免费   308篇
耳鼻咽喉   2064篇
儿科学   4148篇
妇产科学   2901篇
基础医学   18069篇
口腔科学   4643篇
临床医学   8290篇
内科学   33617篇
皮肤病学   4370篇
神经病学   10686篇
特种医学   3073篇
外国民族医学   1篇
外科学   16660篇
综合类   709篇
一般理论   37篇
预防医学   13013篇
眼科学   2951篇
药学   9146篇
中国医学   680篇
肿瘤学   5693篇
  2023年   860篇
  2022年   782篇
  2021年   2964篇
  2020年   1496篇
  2019年   3230篇
  2018年   5157篇
  2017年   3021篇
  2016年   2811篇
  2015年   3139篇
  2014年   3757篇
  2013年   5564篇
  2012年   9548篇
  2011年   10236篇
  2010年   5169篇
  2009年   3774篇
  2008年   8164篇
  2007年   8657篇
  2006年   8057篇
  2005年   7965篇
  2004年   7072篇
  2003年   6648篇
  2002年   6217篇
  2001年   4021篇
  2000年   4712篇
  1999年   3485篇
  1998年   596篇
  1997年   415篇
  1996年   383篇
  1995年   321篇
  1994年   235篇
  1992年   1333篇
  1991年   1107篇
  1990年   988篇
  1989年   798篇
  1988年   669篇
  1987年   653篇
  1986年   648篇
  1985年   542篇
  1984年   400篇
  1983年   304篇
  1979年   346篇
  1975年   279篇
  1974年   324篇
  1973年   359篇
  1972年   302篇
  1971年   315篇
  1970年   295篇
  1969年   300篇
  1968年   272篇
  1967年   242篇
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
991.
992.
BackgroundAnisakis simplex sensitization has been associated with acute, but also with chronic urticaria. The objective of this study is to characterize chronic urticaria with (CU +) and without sensitization (CU-) against the ubiquitous fish parasite A. simplex in a transversal and longitudinal evaluation.Methods16 CU + and 22 CU- patients were included and assessed for Urticaria activity score (UAS), fish-eating habits by standardized questionnaire and cytokine production (assessed by flow cytometric bead-based array) of peripheral blood mononuclear cells after stimulation with A. simplex extract or Concanavalin A (Con A). Patients were randomly put on a fish-free diet for three months and UAS, as well as cytokine production were again assessed. A difference of ≥ 1 in UAS was defined as improvement.ResultsThere was no difference in UAS in both groups. Anisakis induced IL-2, IL-4 and IFN-γ production was higher in CU +. Con A induced IL-6 and IL-10 production was higher in CU +. CU + was associated with higher total fish intake, whereas CU- was associated with oily fish intake. The correlation of UAS was positive with oily fish, but negative with total fish intake.There was a better UAS-based prognosis in CU + without diet. Improvement was associated with higher Con A induced IL-10/IFN-γ as well as IL-10/IL-6 ratios. Further, previous higher oily fish intake was associated with improvement.ConclusionsOur data confirm the different clinical and immunological phenotype of CU +. Our results show a complex relationship between fish-eating habits, cytokine production and prognosis, which could have important consequences in dietary advice in patients with CU. When encountering A. simplex sensitization, patients should not be automatically put on a diet without fish in order to reduce contact with A. simplex products.  相似文献   
993.
Acute pulmonary embolism (PE) bears a significant burden on health and survival. Rapid and accurate risk stratification and management are of paramount importance to ensure the highest quality of care. This present article summarizes currently available and emerging management strategies for the disease. The authors not only review current evidence regarding early therapy of acute PE, including supportive care, anticoagulation, thrombolysis, surgical and catheter-based treatment, but also the possible role of mechanical circulatory support in PE. The authors also discuss complications related to PE and its management.  相似文献   
994.
995.
996.
The objective of this study was to identify the social factors that explain the differences in knowledge with regards to HIV/AIDS among immigrants in the Basque Country (Spain). We conducted a cross-sectional study based on information obtained in the Basque Health Survey for 754 immigrants from: 86 China, 368 Latin America, 237 the Maghreb and 74 Senegal. Odds ratios (95% CI) were calculated from logistic regression models to measure the degree of association between inadequate knowledge regarding transmission, prevention and places where HIV testing is offered, and the independent variables. We found that this inadequate knowledge is associated with place of birth, sex, a lower level of education, immigration status, difficulties in understanding Spanish, and not receiving advice about AIDS in primary care. These findings indicate that initiatives must be developed to promote equity in the provision of healthcare through clinical guidelines, including details of the specific needs of different groups of immigrants and considering gender issues.  相似文献   
997.
Plants belonging to the genus Opuntia spp. are the most abundant of the Cactaceae family, grown throughout America and the Mediterranean central area. Its fruit, known as cactus pear or prickly pear, is an oval berry grouped in different colors. Some studies have shown its antioxidant activities which may help in preventing chronic pathologies such as diabetes. The purpose of the study was to evaluate the antioxidant capacity of three varieties of prickly pear juice (red-purple, white-green and yellow-orange) in five different concentrations (100, 250, 500, 750, and 1000 mg/mL) by DPPH (1,1-diphenyl-2-picrylhydrazyl radical) colorimetric method, selecting the best variety to determine its anticlastogenic potential against methyl methanesulfonate (MMS). The results indicate that the highest antioxidant was found in the juice of the prickly pear red-purple variety (PPRP), in all concentrations. Its anticlastogenic potential was therefore evaluated with a micronucleus assay. The experiment was run over two weeks. A negative control was included along with a positive control with MMS (40 mg/kg), a group of mice treated with PPRP (25 mL/kg), and three groups with PPRP (in doses of 25, 16.5 and 8.3 mL/kg) plus the mutagen. The PPRP was administered daily by oral gavage and the MMS was injected intraperitoneally five days prior to the end of the experiment. Blood samples were obtained at 0, 24, 48, 72 and 96 h in order to determine the frequency of micronucleated polychromatic erythrocytes (MNPE). The results indicated that PPRP is not a genotoxic agent, on the contrary, it may reduce the number of MNPE. In this regard, the PPRP showed an anticlastogenic effect directly proportional to its concentrations. Thus, the highest protection was obtained with a concentration of 25 mL/kg after 48 h of treatment.  相似文献   
998.
999.
ObjectiveSeveral studies have reported the association of genes related to vascular tone, hypertension, oxidative stress and preeclampsia. We investigated the possible association among three polymorphisms in eNOS (as well their haplotypes): one of MTHFR, one of GSTP1 and one of AGT, with severe preeclampsia in Mexican-Mestizo women.MethodsTwo hundred thirty women with severe preeclampsia and 350 control subjects were genotyped; for rs2070744 and rs1799983 of eNOS, rs1801133 of MTHFR, rs1695 of GSTP1 and rs699 of AGT we used real-time PCR allelic discrimination and for VNTR of eNOS, PCR. Allele frequency differences were assessed by χ2. Logistic regression was used to test for associations and for haplotype frequencies using Haploview 4.2.ResultsGenotypic and allelic distribution of the polymorphisms was similar between cases and controls; likewise, haplotype frequencies of the three polymorphisms of eNOS did not differ significantly.ConclusionsTo our knowledge, this is the first time that these polymorphisms have been analyzed together and exclusively in women with severe preeclampsia. However, we did not find an association between polymorphisms of eNOS, MTHFR, GSTP1 and AGT with severe preeclampsia in our population. Additionally, we observed differences in the distribution of the alleles and genotypes of these polymorphisms in our population in comparison to those described in other ethnic groups.  相似文献   
1000.
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