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   3032篇
  免费   329篇
  国内免费   1篇
  2023年   18篇
  2022年   12篇
  2021年   74篇
  2020年   64篇
  2019年   59篇
  2018年   57篇
  2017年   69篇
  2016年   103篇
  2015年   161篇
  2014年   177篇
  2013年   199篇
  2012年   243篇
  2011年   231篇
  2010年   133篇
  2009年   134篇
  2008年   184篇
  2007年   141篇
  2006年   140篇
  2005年   136篇
  2004年   110篇
  2003年   127篇
  2002年   108篇
  2001年   45篇
  2000年   47篇
  1999年   34篇
  1998年   34篇
  1997年   27篇
  1996年   24篇
  1995年   33篇
  1994年   30篇
  1993年   22篇
  1992年   36篇
  1991年   27篇
  1990年   21篇
  1989年   22篇
  1988年   16篇
  1987年   21篇
  1986年   16篇
  1985年   10篇
  1984年   24篇
  1983年   10篇
  1981年   10篇
  1980年   14篇
  1979年   9篇
  1978年   10篇
  1976年   9篇
  1974年   11篇
  1878年   14篇
  1877年   14篇
  1876年   13篇
排序方式: 共有3362条查询结果,搜索用时 93 毫秒
1.
Based on immunomodulatory, osteogenic, and pro-angiogenic properties of adipose-derived stem cells (ASCs), this study aims to assess the safety and efficacy of ASC-derived cell therapies for clinical indications. Two autologous ASC-derived products were proposed to 17 patients who had not experienced any success with conventional therapies: (1) a scaffold-free osteogenic three-dimensional graft for the treatment of bone non-union and (2) a biological dressing for dermal reconstruction of non-healing chronic wounds. Safety was studied using the quality control of the final product (genetic stability, microbiological/mycoplasma/endotoxin contamination) and the in vivo evaluation of adverse events after transplantation. Feasibility was assessed by the ability to reproducibly obtain the final ASC-based product with specific characteristics, the time necessary for graft manufacturing, the capacity to produce enough material to treat the lesion, the surgical handling of the graft, and the ability to manufacture the graft in line with hospital exemption regulations. For 16 patients (one patient did not undergo grafting because of spontaneous bone healing), in-process controls found no microbiological/mycoplasma/endotoxin contamination, no obvious deleterious genomic anomalies, and optimal ASC purity. Each type of graft was reproducibly obtained without significant delay for implantation and surgical handling was always according to the surgical procedure and the implantation site. No serious adverse events were noted for up to 54 months. We demonstrated that autologous ASC transplantation can be considered a safe and feasible therapy tool for extreme clinical indications of ASC properties and physiopathology of disease.  相似文献   
2.
3.
Abstract: Amphiphysin I and II are nerve terminal-enriched proteins that display src homology 3 domain-mediated interactions with dynamin and synaptojanin. It has been demonstrated that the amphiphysins also bind to clathrin, and we have proposed that this interaction may help to target synaptojanin and dynamin to sites of synaptic vesicle endocytosis. To understand better this potential functional role, we have begun to characterize clathrin-amphiphysin interactions. Using PCR from adult human cortex cDNA, we have cloned a number of amphiphysin II splice variants. In in vitro binding assays, the amphiphysin II splice variants display differential clathrin binding and define a 44-amino acid region mediating the interaction. Amphiphysin II truncation and deletion mutants identify two distinct clathrin-binding domains within this region: one with the sequence LLDLDFDP, the second with the sequence PWDLW. Both domains are conserved in amphiphysin I, and saturation binding analysis demonstrates that both sites bind clathrin with approximately equal affinity. The elucidation of clathrin as a splice-specific binding partner for amphiphysin II begins to address the potential functional role(s) for the multiple amphiphysin II splice variants and further supports an important function for clathrin-amphiphysin interactions in protein targeting during endocytosis.  相似文献   
4.
The Australian desert ant Melophorus bagoti often follows stereotypical routes through a cluttered landscape containing both distant panoramic views and obstacles (plants) to navigate around. We created an artificial obstacle course for the ants between a feeder and their nest. Landmarks comprised natural objects in the landscape such as logs, branches, and tussocks. Many ants travelled stereotypical routes home through the obstacle course in training, threading repeatedly the same gaps in the landmarks. Manipulations altering the relations between the landmarks and the surrounding panorama, however, affected the routes in two major ways. Both interchanging the positions of landmarks (transpositions) and displacing the entire landmark set along with the starting position of the ants (translations) (1) reduced the stereotypicality of the route, and (2) increased turns and meanders during travel. The ants might have used the entire panorama in view-based travel, or the distal panorama might prime the identification and use of landmarks en route. Despite the large data set, both options (not mutually exclusive) remain viable.  相似文献   
5.
A method for the determination of benzoic acid down to concentrations of 10 ng/ml in plasma or urine is described. After addition of an internal standard, benzoic acid is extracted at acid pH into diethyl ether. Both compounds are derivatized with pentafluorobenzyl bromide. The derivatives are determined by gas chromatography using a 43Ni electron-capture detector. Hippuric acid is hydrolysed in plasma and urine and total benzoic acid is determined by the same technique.  相似文献   
6.
Inflammatory reaction to ocular trauma is known to be related to prostaglandins. To further evaluate this phenomenon in human, PGE1 and E2 were measured by R.I.A. after silicic acid chromatography in aqueous humour of 26 patients before and 3 days after surgery for unilateral senile cataract (posterior chamber implant after extracapsular surgery). 13 out of these patients were treated with indomethacin by enteral route and 13 were not treated.PGE2 levels increased in all non-treated patients from : m < 214 pg/ml before surgery, to 2666 ± 869 pg/ml (range : 257 - 8728) p < 0.001 after surgery. PGE2 levels did not increase in indomethacin-treated patients. PGE1 levels did not increase significantly in non-treated as in treated patients.1) Intra-ocular surgery is followed in human by a constant increase of the only PGE2 in the aqueous humour. 2) Indomethacin inhibits this increase. 3) The post-surgical increase in the permeability of blood-aqueous barrier appears to be related to a release of PGE2.  相似文献   
7.
Patients with primary polycythaemia may present clinical features which lead to an erroneous diagnosis of intracerebral neoplasm. Three such cases are described in detail in this report.  相似文献   
8.
9.
Antoine Lemaire 《Andrologie》2004,14(2):160-163
Anejaculation corresponds to absence of ejaculation during orgasm. Most men with anejaculation are aware of their abnormality, but some poorly educated subjects consult for infertility and anejaculation is only suspected on the sperm count. The patient must therefore be questioned about his capacity to ejaculate, for example while sleeping, by masturbation or, less frequently, according to various coital positions. There are various types of anejaculation. Clinical interview is certainly the most important phase of the diagnostic work-up, which is based on analysis of sexual signs and orgasm. It is essential to define the primary or secondary nature of the disorder. After confirming the diagnosis of anejaculation and distinguishing it from retrograde ejaculation and asthenic ejaculation, orgasm without ejaculation and without normal ejaculation outside of coitus must be distinguished from anejaculation without orgasm but with normal ejaculation outside of coitus. The causes of anejaculation may be organic and psychological. The main psychological factors likely to play a role in anejaculation without orgasm can be classified into six categories. However, the presence of one of these factors in a patient with anejaculation does not necessarily imply that it is the cause of the sexual dysfunction; the diagnosis of psychogenic anejaculation is a diagnosis of exclusion after all possible organic causes have been eliminated.  相似文献   
10.
Vacuoles were isolated from Acer pseudoplatanus cell suspension culture using a one-step procedure involving the lysis of the protoplast plasmalemma through a gradient of Ficoll containing DEAE-Dextran. The vacuole suspensions were slightly contaminated by other organelles (less than 5%) and the isolated vacuoles readily accumulated neutral red. Since α-mannosidase was located exclusively in the vacuoles it was used as a convenient marker. It was shown that the number of vacuoles per protoplast decreased as the cell aged. Studies on the biochemical composition of the isolated vacuoles indicated that amino acids, organic acids and protein contents varied with the cell culture cycle, emphasizing the dynamic status of the vacuolar system in cell suspension cultures of Acer pseudoplatanus.  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