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   530篇
  免费   13篇
  国内免费   19篇
耳鼻咽喉   1篇
儿科学   13篇
妇产科学   15篇
基础医学   76篇
口腔科学   41篇
临床医学   31篇
内科学   119篇
神经病学   26篇
特种医学   100篇
外国民族医学   1篇
外科学   40篇
综合类   9篇
预防医学   14篇
药学   52篇
肿瘤学   24篇
  2022年   4篇
  2021年   9篇
  2019年   6篇
  2018年   6篇
  2016年   6篇
  2015年   7篇
  2014年   13篇
  2013年   7篇
  2012年   21篇
  2011年   15篇
  2010年   12篇
  2009年   11篇
  2008年   23篇
  2007年   30篇
  2006年   18篇
  2005年   20篇
  2004年   14篇
  2003年   19篇
  2002年   20篇
  2001年   14篇
  2000年   18篇
  1999年   16篇
  1998年   10篇
  1997年   25篇
  1996年   13篇
  1995年   9篇
  1994年   16篇
  1993年   11篇
  1992年   6篇
  1991年   5篇
  1990年   7篇
  1989年   25篇
  1988年   14篇
  1987年   12篇
  1986年   15篇
  1985年   11篇
  1984年   6篇
  1983年   3篇
  1982年   8篇
  1981年   3篇
  1980年   9篇
  1979年   4篇
  1976年   7篇
  1975年   4篇
  1974年   4篇
  1973年   3篇
  1972年   2篇
  1969年   3篇
  1968年   2篇
  1966年   5篇
排序方式: 共有562条查询结果,搜索用时 15 毫秒
1.
Zhang SC  Wege C  Jeske H 《Virology》2001,290(2):249-260
Two movement proteins (BV1 and BC1) facilitate the intra- and intercellular transport of begomoviruses in plants. In contrast to other geminiviruses the movement protein BC1 of Abutilon mosaic virus (AbMV) remained in the supernatant after centrifuging plant extracts at 20,000 g. To test whether this unusual behavior results from a distinct intracellular distribution of the protein, the BC1 gene has been fused to the gene of green fluorescent protein (GFP). The resulting plasmids were delivered into nonhost plants (Allium cepa) as well as into mature and immature cells of host plants (Nicotiana tabacum, N. benthamiana) by biolistic bombardment for transient expression in planta. BC1 directed GFP to two different cellular sites. In the majority of nonhost cells as well as in mature cells of host leaves, BC1 was mainly localized in small punctate flecks at the cell periphery or, to a lesser extent, around the nucleus. In sink leaves of host plants, GFP:BC1 additionally developed disc-like structures in the cell periphery. Cobombardment of GFP:BC1 with its cognate infectious DNA A and B did not change their subcellular distribution patterns in source leaves but led to the formation of peculiar needle-like structures in sink leaves. The nuclear shuttle protein (BV1) of AbMV accumulated mainly inside the nuclei as shown by immunohistochemical staining and GFP tagging. In sink cells of host plants it was mobilized to the plasma membrane and to the nucleus of the neighboring cell by coexpressed BC1, GFP:BC1, BC1:GFP, or after cobombardment with the cognate viral DNA. Only under these conditions were GFP:BC1 and BC1:GFP also found in the recipient cell.  相似文献   
2.
Transcript mapping of Abutilon mosaic virus, a geminivirus   总被引:4,自引:0,他引:4  
S Frischmuth  T Frischmuth  H Jeske 《Virology》1991,185(2):596-604
  相似文献   
3.
Prevalence of anaemia among Nigerian toddlers is reported to be high, and may cause significant morbidity, affects brain development and function, and results in weakness and fatigue. Although, iron fortification can reduce anaemia, yet the effect on gut microbiota is unclear. This open-label randomised study in anaemic malnourished Nigerian toddlers aimed to decrease anaemia without affecting pathogenic gut bacteria using a multi-nutrient fortified dairy-based drink. The test product was provided daily in different amounts (200, 400 or 600 mL, supplying 2.24, 4.48 and 6.72 mg of elemental iron, respectively) for 6 months. Haemoglobin, ferritin, and C-reactive protein concentrations were measured to determine anaemia, iron deficiency (ID) and iron deficiency anaemia (IDA) prevalence. Faecal samples were collected to analyse gut microbiota composition. All three dosages reduced anaemia prevalence, to 47%, 27% and 18%, respectively. ID and IDA prevalence was low and did not significantly decrease over time. Regarding gut microbiota, Enterobacteriaceae decreased over time without differences between groups, whereas Bifidobacteriaceae and pathogenic E. coli were not affected. In conclusion, the multi-nutrient fortified dairy-based drink reduced anaemia in a dose-dependent way, without stimulating intestinal potential pathogenic bacteria, and thus appears to be safe and effective in treating anaemia in Nigerian toddlers.  相似文献   
4.
We report molecular evidence of Tula virus infection in an immunocompetent patient from Germany who had typical signs of hantavirus disease. Accumulating evidence indicates that Tula virus infection, although often considered nonpathogenic, represents a threat to human health.  相似文献   
5.
Varying dosages of pentasaccharide (400-800 nmol/kg) were compared to a 250-U/kg single bolus dosage of unfractionated heparin (UFH) in a dog model of hemodialysis. Several laboratory assays were used to monitor the effects of pentasaccharide and UFH. The pentasaccharide did not produce any anticoagulant effects as measured by the activated partial thromboplastin time. However, in the anti-Xa chromogenic assay and the Heptest assays, there was a dose-dependent prolongation after pentasaccharide administration. In the group of dogs administered 800 nmol/kg of pentasaccharide, there was a 50% decrease in the thrombin antithrombin (TAT) complex level after 60 minutes on dialysis. In the UFH-treated dogs, wide variations in assays were observed. There was a marked elevation in the activated partial thromboplastin time and Heptest assays up to 6 hours after UFH administration. Both anti-Xa and anti-IIa activity was measured up to 4 hours. In the TAT assay, UFH was found to have a stronger effect in suppressing the formation of TAT in comparison to the pentasaccharide. These results suggest that pentasaccharide can be used as a replacement for UFH in a dog model of hemodialysis to keep the dialysis circuit patent. In addition, the anti-Xa-based assays such as the Heptest and the chromogenic anti-Xa assays can be used to monitor the effects of pentasaccharide in this model.  相似文献   
6.
The conventional management of thrombotic disorders is based on the use of heparin, oral anticoagulants, and aspirin. The development of low molecular weight heparins and the synthesis of heparinomimetics such as the chemically synthesized pentasaccharide represent a refined use of heparin. Aspirin still remains the lead drug in the management of thrombotic and cardiovascular disorders. The newer antiplatelet drugs such as the adenosine diphosphate receptor inhibitors, glycoprotein IIb/IIIa (GPIIb/IIIa) inhibitors and other specific inhibitors have limited effects and have been tested in patients who have already been treated with aspirin. The oral anticoagulants such as warfarin provide a convenient and affordable approach in the long-term outpatient management of thrombotic disorders. The optimized use of these drugs still remains the approach of choice to manage thrombotic disorders. The new anticoagulant drugs target specific sites in the hemostatic network. There is a major thrust on the development of orally bioavailable anticoagulant drugs to replace oral anticoagulants. Heparin and low molecular weight heparins have been considered with various chemical enhancers for absorption. Both the factor Xa and antithrombin agents have been developed for oral use and some of these agents are in clinical development. Besides the limited bioavailability, the therapeutic indices of some of these drugs have been rather disappointing. Factor Xa inhibitors such as the pentasaccharides have undergone aggressive clinical development. The newer antiplatelet drugs have added a new dimension in the management of thrombotic disorders. The newer drugs are attractive for several reasons; however, none of these are expected to completely replace the conventional drugs in polytherapeutic approaches. It is conceivable that some of the newer drugs in combined modalities may mimic the broad therapeutic spectrum of heparins and warfarin. However, clinical validation is required for the therapeutic interchange for specific indications.  相似文献   
7.
8.
Heparin-induced thrombocytopenia (HIT) Type II represents a disease spectrum associated with a high risk of thrombosis leading to limb loss and death. The pathophysiology of HIT is based on the development of antibodies to the heparin-platelet factor 4 (PF4) complex. Unfractionated heparin (UFH) is heterogeneous in molecular chain length and degree of sulfation accounting in part, for, the heterogeneity of HIT antibodies. Because of its smaller size, low-molecular-weight heparin (LMWH) does not interact with PF4 and platelets as efficiently as does UFH. This translates into a lower risk of immune sensitization with LMWH than with UFH treatment. LMWH is less likely than UFH to cause antibody generation and thus patients do not develop clinical HIT at the same frequency with LMWH as with UFH treatment. The antibodies generated by LMWH treatment are more often immunoglobulin A (IgA) and IgM as opposed to IgG antibodies, which are associated with symptomatic clinical HIT generated by exposure to UFH. However, platelet activation/aggregation can occur from LMWHs in the presence of most pre-existing HIT antibodies that had been generated from UFH exposure, although the response is less than that caused by UFH plus HIT antibody. With the expanded use of LMWH, the frequency of clinical HIT may naturally decline, given that LMWHs are less likely to generate HIT antibody.  相似文献   
9.

Purpose

It is unclear whether obstructing colorectal cancer (CRC) has a worse prognosis than non-obstructing CRC. Of CRC patients, 10–28% present with symptoms of acute obstruction. Previous studies regarding obstruction have been primarily based on short-term outcomes, risk factors and treatment modalities. With this study, we want to determine the long-term survival of patients presenting with acute obstructive CRC.

Methods

This single-centre observational retrospective cohort study includes all CRC patients who underwent surgery between December 2004 and 2010. Patients were divided into two groups: ileus and no ileus. Survival analyses were performed for both groups. Additional survival analyses were performed in patients with and without synchronous metastases. The primary outcome was survival in months.

Results

A total of 1236 patients were included in the analyses. Ileus occurred in 178 patients (14.4%). The 5-year survival for patients with an ileus was 32% and without 60% (P?<?0.01). In patients without synchronous metastases, survival with and without an ileus was 40.9 and 68.4%, respectively (P?<?0.01). If ileus presentation was complicated by a colon blowout, 5-year survival decreased to 29%. No significant difference was found in patients with synchronous metastases. Survival at 5 years in this subgroup was 10 and 12% for patients with and without an ileus, respectively (P?=?0.705).

Conclusions

Patients with obstructive CRC have a reduced short-term overall survival. Also, long-term overall survival is impaired in patients who present with acute obstructive CRC compared to patients without obstruction.
  相似文献   
10.
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