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   24566篇
  免费   1354篇
  国内免费   67篇
耳鼻咽喉   390篇
儿科学   561篇
妇产科学   655篇
基础医学   3454篇
口腔科学   2117篇
临床医学   1642篇
内科学   5097篇
皮肤病学   464篇
神经病学   2384篇
特种医学   651篇
外科学   2836篇
综合类   59篇
一般理论   8篇
预防医学   2166篇
眼科学   551篇
药学   1875篇
中国医学   180篇
肿瘤学   897篇
  2023年   205篇
  2022年   307篇
  2021年   691篇
  2020年   412篇
  2019年   652篇
  2018年   1034篇
  2017年   733篇
  2016年   724篇
  2015年   742篇
  2014年   874篇
  2013年   1269篇
  2012年   2128篇
  2011年   2375篇
  2010年   1162篇
  2009年   782篇
  2008年   1710篇
  2007年   1668篇
  2006年   1501篇
  2005年   1379篇
  2004年   1326篇
  2003年   1094篇
  2002年   848篇
  2001年   352篇
  2000年   365篇
  1999年   259篇
  1998年   119篇
  1997年   89篇
  1996年   72篇
  1995年   58篇
  1994年   52篇
  1993年   47篇
  1992年   76篇
  1991年   71篇
  1990年   51篇
  1989年   50篇
  1988年   51篇
  1987年   36篇
  1986年   41篇
  1985年   68篇
  1984年   41篇
  1983年   25篇
  1982年   25篇
  1981年   36篇
  1980年   34篇
  1978年   33篇
  1977年   24篇
  1974年   28篇
  1971年   25篇
  1970年   26篇
  1969年   24篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
951.
952.
Summary The authors report data obtained from a 3-year study of CSII and humanized insulin (semi-synthetic human insulin) administered to 18 insulin-dependent subjects in the outpatient clinic. The aim of this study was to evaluate the validity of insulin pumps in long-term treatment. Metabolic parameters were significantly improved (p<0.001) in the first month and remained so with only slight alterations throughout treatment. The authors underline some metabolic problems (ketosis) caused by malfunctioning of the insulin pumps, by the difficulties with the infusion sytem or by nodular skin lesions at the infusion site. Only these lesions called for treatment to be discontinued in 4 patients. The highest incidence of nodular skin lesions was seen after one year’s uninterrupted treatment and they seem connected to the duration of treatment rather than to the patients’ negligence (inadequate hygiene, delayed needle substitution). The authors conclude that CSII treatment is valid over short-term periods, whereas it presents drawbacks over long-term administration.  相似文献   
953.
We have evaluated the sensitivity of the classical blood subinoculation method, modified through cyclophosphamide treatment of transferred mice, for the detection of occult parasitaemias in Trypanosoma cruzi chronically infected mice. Besides its simplicity, the method was shown to be highly sensitive for both the "chronic" phase parasites (99% of chronic cases were shown to harbour occult parasitaemias) and for the acute phase parasites (T. cruzi could be detected in 53.8% of animals transferred with one Y strain parasite and in 20% of animals transferred with one CL strain parasite). Using acute phase bloodforms, the assay proved to be more sensitive than conventional subinoculation when dealing with the CL, but not the Y strain of the parasite. With the help of this parasite detection tool, we have studied during a one year period, the evolution of subpatent parasitaemias in a group of mice which survived through chemotherapy from lethal acute phase of T. cruzi infection. Cyclophosphamide transfer assay revealed occult parasitaemias in 100% of the chronic animals, nevertheless, continuous and discontinuous patterns of positivity were observed.  相似文献   
954.

Background

Antiretroviral therapy (ART) saved millions from HIV-1 infection and AIDS, but some patients do not experience adequate CD4+ T cells gain despite achieving viral suppression. The genetic component of this condition is not yet completely elucidated.

Objective

To identify predictive genetic markers of immune response to ART.

Methods

Case–control study. Out of 176 HIV-infected patients recruited in the city of Recife, Northeast Brazil, 67 patients with no immunologic response were the cases and the remaining 109 patients who responded were the controls. A set of 94 selected single nucleotide polymorphisms (SNPs) involved in antiretroviral drugs pharmacodynamic pathways and immune system homeostasis were genotyped, while the remaining 48 were ancestry informative markers (AIMs) for controlling for eventual hidden population structure.

Results

Male patients were overrepresented in non-responder group (p = 0.01). Non-responders also started with lower absolute CD4+ T cell counts (p < 0.001). We found five SNPs significantly associated with the outcome, being three more frequent in non-responders than responders: rs2243250 (IL4) A allele (p = 0.04), rs1128503 (ABCB1) A allele (p = 0.03) and rs707265 (CYP2B6) A allele (p = 0.02), whereas the other two were less frequent in non-responders: rs2069762 (IL2) C allele (p = 0.004) and rs4646437 (CYP3A4) A allele (p = 0.04).

Conclusion

Some significant univariate associations remained independently associated at multivariate survival analysis modeling, such as pre-treatment CD4+ T cells counts, IL2 and ABCB1 genotypes, and use of protease inhibitors, yielding a predictive model for the probability for immune response. More studies are needed to unravel the genetic basis of ART immunological non-response.  相似文献   
955.

Background

Heated water-based exercise (HEx) promotes a marked reduction of blood pressure (BP), but it is not entirely clear whether its effects on BP persist after cessation of HEx.

Methods

We analyzed the effects of cessation of HEx on 24-hour ambulatory BP monitoring (ABPM) in patients with resistant hypertension (RH). Thirty-two patients (aged 53 ± 6 years) with RH (4 to 6 antihypertensive drugs) were randomly assigned to HEx (n = 16) or control (n = 16) groups. Antihypertensive therapy remained unchanged during the protocol. The HEx group participated in 36 sessions (60 minutes) in a heated pool (32oC [89.6°F]) for 12 weeks (training), followed by 12 weeks of cessation of training. The control group was evaluated during the same period and instructed to maintain their habitual activities.

Results

HEx and control groups had similar BP levels at baseline. HEx training reduced the 24-hour systolic (–19.5 ± 4.6 vs 3.0 ± 0.7 mm Hg, P = 0.001) and diastolic BP (–11.1 ± 2.4 vs 2.06 ± 0.9 mm Hg, P = 0.001) at week 12, compared with the control group. After 12 weeks of training cessation (week 24), 24-hour BP remained significantly lower in the HEx group than in the control group (–9.6 ± 3.8 vs 6.3 ± 3.5 mm Hg, P = 0.01 and –7.5±2.2 vs 2.2 ± 1.0 mm Hg, P = 0.009, for systolic and diastolic BP, respectively), although these differences were attenuated.

Conclusions

BP remained lower after cessation of 12-week training among patients with RH who underwent HEx compared with the controls. The carryover effects of HEx on BP may help to overcome the challenging problem of exercise compliance in long-term follow-up.  相似文献   
956.
Catastrophic antiphospholipid syndrome (CAPS) is an acutely devastating situation characterized by widespread thrombotic microangiopathy in the presence of elevated titers of antiphospholipid antibodies. We describe a 57-year old woman who underwent liver transplantation for primary sclerosing cholangitis and developed this malignant variant of the antiphospholipid syndrome.  相似文献   
957.
Central nervous system (CSN) involvement in schistosomiasis is an ectopic manifestation with a large variety of clinical forms, including pseudotumoral, which occurs in isolated cases and is rare. Three patients with epidemiological indications of this pathology were examined; the clinical picture included lower-back pain irradiating to lower limbs, associated with progressive flaccid paraparesis and sphincterial disturbances in cases in which the spinal chord was involved; while in cases with encephalitic impairment, headache, dizziness and cerebellar syndrome, characterized by dysarthria and right-side dysgraphia, were present. Magnetic resonance imaging (MRI) showed a growing process in all cases; cerebrospinal fluid (CSF) characteristics and biological markers were compatible with neuroschistosomiasis (NS). Biopsy of the lesions confirmed this diagnosis in one case. After specific treatment with schistosomicides and corticosteroids, clinical, radiological and laboratorial improvement was observed.  相似文献   
958.
959.
960.
The aim of the study was to evaluate serum acid-labile subunit (ALS) concentrations and their relationship with other parameters of the human ternary IGF-I-binding protein (IGFBP) complex in girls with central precocious puberty (CPP) before and after pharmacological arrest of puberty. We studied serum ALS, free IGF-I, total IGF-I, IGFBP-3 levels and IGFBP-3 protease activity in 13 girls, aged 1.6-7.8 yr (mean, 5.9 +/- 2.2), diagnosed as having CPP before and after 6 and 12 months of GnRH analog (GnRHa) therapy. The ALS SD score before treatment was high (1.4 +/- 0.72) and decreased significantly after 6 and 12 months of GnRHa therapy [0.4 +/- 0.54 (P < 0.01) and -0.4 +/- 0.61 (P < 0.01), respectively]. Serum IGF-I and IGFBP-3 were also increased before treatment, but both of these factors remained elevated after 6 and 12 months of GnRH-A therapy [IGF-I SD score, 3.20 +/- 1.64, 2.92 +/- 1.82, and 3.68 +/- 1.94 (P = NS), respectively; IGFBP-3 SD score, 1.02 +/- 0.53, 0.94 +/- 0.68, and 1.22 +/- 0.87 (P = NS), respectively]. Serum free IGF-I levels and IGFBP-3 proteolytic activity did not vary significantly from their pretreatment values during GnRHa therapy. In conclusion, serum ALS levels were elevated in girls with CPP and decreased significantly during the first year of GnRHa therapy. Serum IGF-I and IGFBP-3 levels were also increased before therapy, but their levels were not influenced by treatment. The ALS decrease seems to be the sole GH-dependent factor that parallels the decreases in steroid levels and growth velocity during GnRHa therapy.  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