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   3002篇
  免费   492篇
  国内免费   6篇
耳鼻咽喉   9篇
儿科学   80篇
妇产科学   184篇
基础医学   300篇
口腔科学   29篇
临床医学   1148篇
内科学   572篇
皮肤病学   49篇
神经病学   171篇
特种医学   94篇
外科学   304篇
综合类   30篇
预防医学   234篇
眼科学   30篇
药学   99篇
中国医学   2篇
肿瘤学   165篇
  2024年   11篇
  2023年   66篇
  2022年   13篇
  2021年   68篇
  2020年   50篇
  2019年   48篇
  2018年   147篇
  2017年   142篇
  2016年   145篇
  2015年   139篇
  2014年   145篇
  2013年   166篇
  2012年   150篇
  2011年   153篇
  2010年   121篇
  2009年   145篇
  2008年   155篇
  2007年   131篇
  2006年   112篇
  2005年   94篇
  2004年   87篇
  2003年   85篇
  2002年   80篇
  2001年   81篇
  2000年   77篇
  1999年   75篇
  1998年   56篇
  1997年   79篇
  1996年   64篇
  1995年   60篇
  1994年   49篇
  1993年   51篇
  1992年   57篇
  1991年   45篇
  1990年   45篇
  1989年   34篇
  1988年   33篇
  1987年   28篇
  1986年   28篇
  1985年   21篇
  1984年   19篇
  1983年   16篇
  1982年   9篇
  1981年   15篇
  1979年   9篇
  1978年   8篇
  1977年   10篇
  1976年   14篇
  1975年   16篇
  1974年   8篇
排序方式: 共有3500条查询结果,搜索用时 15 毫秒
101.
This game can be conducted with as many as 50 and as few as 15 players. The optimum size includes 4-5 Board members and 4-6 participants in each of the four small-group scenarios. The game takes about 11/2-2 hours to play. This includes a break between Part I and Part II. Existing state and national laws and policies are used in the game so that participants may understand their effects and limitations. The game has no winners or losers. Everyone gains if the decision markers are able to consider the needs of the individuals and the needs of the public, though some individuals may or may not benefit as much as others. This, however, is reality and is inherent in the policy-making process. In primary care, nurse practitioners (NPs) have a crucial responsibility to weigh the impact of their decisions on their clients and the community. The "Inside Story" integrates recommended NP curriculum content such as ethical decision making and health policy into a creative and powerful educational experience. This simulation game could be adapted for other topics with ethical, legal, and political implications such as issues regarding allocation of scarce resources. It could be played among students or professionals from many disciplines as part of their curriculum or in a continuing education offering.  相似文献   
102.
Prospective evaluation of posttransfusion hepatitis   总被引:1,自引:0,他引:1  
The incidence of posttransfusion hepatitis (PTH) was determined prospectively at our institution. An active surveillance program of transfused surgical patients was set up; alanine aminotransferase (ALT) levels were determined before transfusion and at monthly intervals for 6 months after transfusion. Patients with confirmed ALT values greater than 2.5 times the upper reference values were referred to the out-patient clinics for diagnosis. Of 4051 surgical patients who underwent transfusion between January 1986 and December 1989, 2459 (60.7%) were enrolled in the surveillance program, and 1018 (25.1%) completed the follow-up; 238 patients received autologous blood only and were used as controls. No PTH was observed in the control patients, and the incidence of the disease in patients receiving homologous blood was 10.97 percent in 1986, 6.58 percent in 1987, 5.55 percent in 1988, and 4.29 percent in 1989; the decreasing trend is significant (p = 0.018).  相似文献   
103.
The incidence of malignant melanoma is increasing worldwide. In Spain, its incidence is increasing faster than any other cancer type, with a 5-year survival rate of about 85%. The impact and characteristics of malignant melanoma in the Spanish population can be ascertained from the national melanoma registry of the Academia Española de Dermatología y Venereología. This review presents consensus group recommendations for the diagnosis, staging and treatment of malignant melanoma in Spain. Incidence and mortality are discussed, as well as evaluation of various prevention and treatment strategies. Prognostic factors, such as BRAF and C-KIT mutations, which are expected to become routine staging procedures over the next few years, are outlined, especially in relation to treatment options. The use of recently approved targeted agents such as ipilimumab, a cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) inhibitor, and vemurafenib, a BRAF inhibitor, in metastatic disease are also discussed.  相似文献   
104.
The chemical α-asarone is an important active substance of the Acori graminei rhizome (AGR). It has pharmacological effects that include antihyperlipidemic, antiinflammatory, and antioxidant activity. Our aim was to study the effects α-asarone on nitric oxide (NO) levels in the hippocampus and temporal cortex of the rat after injection of the fraction 25–35 from amyloid-β (Aβ(25–35)). In addition we examined the working spatial memory in an eight-arm radial maze. Our results showed a significant increase of nitrites in the hippocampus and temporal cortex of Aβ(25–35)-treated rats. Other evidence of neuronal damage was the expression of a glial-fibrillar-acid protein and a silver staining. There were impairments in the spatial memory evaluated in the eight-arm radial maze. We wanted to determine whether α-asarone improves the memory correlated with NO overproduction and neuronal damage caused by the injection of Aβ(25–35) into rats. Then animals received a 16-day treatment of α-asarone before the Aβ(25–35) injection. Our results show a significant decrease of nitrite levels in the hippocampus and temporal cortex, without astrocytosis and silver-staining cells, which correlates with memory improvement in the α-asarone-treated group. Our results suggest that α-asarone may protect neurons against Aβ(25–35)–caused neurotoxicity by inhibiting the effects of NO overproduction in the hippocampus and temporal cortex.  相似文献   
105.
Technological advances in health care have made it possible to restore and prolong life for patients who would have died in the past. Unfortunately, one consequence of this is that some patients linger in intensive care units (ICUs), dependent on the technologies but with no hope of recovery. Therefore, decisions regarding withdrawal of life-support treatment are increasingly being faced by the health-care team.

This study aimed to explore the lived experience of critical care nurses who had cared for patients during withdrawal of life-support. The methodology employed was interpretive phenomenology. Interviews were conducted with seven critical care nurses, with the meanings of the experience of withdrawal of life-support treatment for these nurses extrapolated from the narratives and clustered into themes.

The study highlighted the importance of honest communication during the processes of decision-making and withdrawal of treatment. It was important for these nurses to be sure that family members were well-informed regarding the process of withdrawal of life-support treatment and that they could provide support and ensure that the patient's comfort and dignity were maintained during the process. The need to debrief after the event became evident but formal debriefing processes were rarely undertaken.  相似文献   

106.

Objective

To analyze the benefits of external cephalic version (ECV) with epidural analgesia at term and labor induction just after the procedure.

Materials and methods

This is a retrospective observational study with patients who did not want trying a breech vaginal delivery and decided trying an ECV with epidural analgesia at term and wanted labor induction or cesarean section after the procedure. We present the results of 40 ECV with epidural analgesia at term and labor induction or cesarean section just after the ECV.

Results

ECV succeeded in 26 out of 40 (65%) patients. Among the 26 successful ECV, 6 delivered by cesarean (23.1%). 20 patients delivered vaginally (76.9%; 50% of all patients).

Conclusion

Considering that a high number of cesarean deliveries can be avoided, induction of labor after ECV with epidural analgesia at term can be considered after being discussed in selected patient.  相似文献   
107.
108.
The distribution of eight putative adhesins that are not encoded in the locus for enterocyte effacement (LEE) in 139 Shiga toxin-producing Escherichia coli (STEC) of different serotypes was investigated by PCR. Five of the adhesins (Iha, Efa1, LPF(O157/OI-141), LPF(O157/OI-154), and LPF(O113)) are encoded in regions corresponding to genomic O islands of E. coli EDL933, while the other three adhesins have been reported to be encoded in the STEC megaplasmid of various serotypes (ToxB [O157:H7], Saa [O113:H21], and Sfp [O157:NM]). STEC strains were isolated from humans (n = 54), animals (n = 52), and food (n = 33). They were classified into five seropathotypes (A through E) based on the reported occurrence of STEC serotypes in human disease, in outbreaks, and in the hemolytic-uremic syndrome (M. A. Karmali, M. Mascarenhas, S. Shen, K. Ziebell, S. Johnson, R. Reid-Smith, J. Isaac-Renton, C. Clark, K. Rahn, and J. B. Kaper, J. Clin. Microbiol. 41:4930-4940, 2003). The most prevalent adhesin was that encoded by the iha gene (91%; 127 of 139 strains), which was distributed in all seropathotypes. toxB and efa1 were present mainly in strains of seropathotypes A and B, which were LEE positive. saa was present only in strains of seropathotypes C, D, and E, which were LEE negative. Two fimbrial genes, lpfA(O157/OI-141) and lpfA(O157/OI-154), were strongly associated with seropathotype A. The fimbrial gene lpfA(O113) was present in all seropathotypes except for seropathotype A, while sfpA was not present in any of the strains studied. The distribution of STEC adhesins depends mainly on serotypes and not on the source of isolation. Seropathotype A, which is associated with severe disease and frequently is involved in outbreaks, possesses a unique adhesin profile which is not present in the other seropathotypes. The wide distribution of iha in STEC strains suggested that it could be a candidate for vaccine development.  相似文献   
109.
Xenograft models of human diffuse large B cell lymphoma (DLBCL) are widely used to test new drugs against this neoplasia. Most of them, however, are subcutaneous xenografts that do not show a disseminated disease as it is found in the human neoplasia. In this paper, we aimed to develop a disseminated xenograft model of DLBCL by performing a subcutaneous passage of DLBCL cells before their intravenous injection in mice. WSU-DLCL-2 (WSU) cells were injected into both flanks of NOD/SCID mice. The subcutaneous tumours were disaggregated and a cell suspension (WSU-SC) was obtained. Two groups of 10 NOD/SCID mice were intravenously injected with WSU-SC or WSU cells. All mice injected with WSU-SC cells developed lymphoma in 32-47?days and showed lymph node and bone marrow infiltration. WSU-SC cells showed a significantly higher engraftment rate and faster dissemination than WSU cells after intravenous injection in mice. When molecularly compared, WSU-SC cells showed higher expression levels of FAK, p130Cas and phosphorylated AKT than WSU cells. The subcutaneous passage enhanced the engraftment and the metastatic capacity of WSU cells, allowing the generation of a rapid and disseminated DLBCL xenograft model. The aggressive behaviour of WSU-SC cells was associated with increased p130Cas and FAK expression and AKT activation.  相似文献   
110.
Mutations in the voltage-gated chloride/proton antiporter ClC-5 gene, CLCN5, are associated with Dent’s disease, an X-linked renal tubulopathy. Our interest is to identify and characterize disease-causing CLCN5 mutations, especially those that alter the splicing of the pre-mRNA. We analyzed the CLCN5 gene from nine unrelated Spanish Dent’s disease patients and their relatives by DNA sequencing. Pre-mRNA splicing analysis was performed by RT-PCR. Seven new mutations were identified, consisting of three missense mutations (C219R, F273L, and W547G), one splice-site mutation (IVS-2A > G), one deletion (976delG), and two non-sense mutations (Y140X and W314X). We found that missense mutation W547G also led to increased expression of a new alternative isoform lacking exons 10 and 11 that was expressed in several human tissues. In addition, we describe another novel CLCN5 splicing variant lacking exon 11 alone, which was expressed only in human skeletal muscle. We conclude that missense mutation W547G can also alter the expression levels of a CLCN5 mRNA splicing variant. This type of mutation has not been previously described in the CLCN5 gene. Our results support the importance of a routine analysis at the pre-mRNA level of mutations that are commonly assumed to cause single amino acids alterations.  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