全文获取类型
收费全文 | 999篇 |
免费 | 97篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 43篇 |
儿科学 | 44篇 |
妇产科学 | 10篇 |
基础医学 | 126篇 |
口腔科学 | 27篇 |
临床医学 | 62篇 |
内科学 | 163篇 |
皮肤病学 | 20篇 |
神经病学 | 65篇 |
特种医学 | 23篇 |
外科学 | 232篇 |
综合类 | 31篇 |
预防医学 | 47篇 |
眼科学 | 72篇 |
药学 | 61篇 |
肿瘤学 | 73篇 |
出版年
2023年 | 7篇 |
2022年 | 7篇 |
2021年 | 31篇 |
2020年 | 20篇 |
2019年 | 31篇 |
2018年 | 20篇 |
2017年 | 23篇 |
2016年 | 25篇 |
2015年 | 27篇 |
2014年 | 36篇 |
2013年 | 54篇 |
2012年 | 64篇 |
2011年 | 41篇 |
2010年 | 39篇 |
2009年 | 39篇 |
2008年 | 60篇 |
2007年 | 55篇 |
2006年 | 36篇 |
2005年 | 34篇 |
2004年 | 33篇 |
2003年 | 39篇 |
2002年 | 36篇 |
2001年 | 41篇 |
2000年 | 28篇 |
1999年 | 29篇 |
1998年 | 12篇 |
1997年 | 17篇 |
1996年 | 9篇 |
1995年 | 8篇 |
1994年 | 12篇 |
1993年 | 7篇 |
1992年 | 13篇 |
1991年 | 9篇 |
1990年 | 21篇 |
1989年 | 8篇 |
1987年 | 5篇 |
1985年 | 9篇 |
1984年 | 11篇 |
1983年 | 9篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1972年 | 6篇 |
1971年 | 8篇 |
1970年 | 4篇 |
1969年 | 9篇 |
1968年 | 5篇 |
1967年 | 7篇 |
1966年 | 5篇 |
排序方式: 共有1099条查询结果,搜索用时 46 毫秒
1.
2.
Aaron R Jensen Richard Milner John Gaughan Harsh Grewal 《JSLS, Journal of the Society of Laparoendoscopic Surgeons》2005,9(3):322-327
BACKGROUND: We recently implemented the use of an ex-vivo porcine model to teach residents the fundamentals of performing a laparoscopic Nissen fundoplication. METHODS: Residents were trained using intact porcine esophagus, stomach, and spleen placed in a standard video-trainer. They were later asked to complete a survey containing a course evaluation. RESULTS: Sixteen residents (R1-R4) completed the survey. They agreed that (1) the exercise was a valuable use of their limited time, (2) repeating the exercise will be of additional benefit, (3) it will improve their ability to perform or assist in an actual case in the OR, and (4) the surgical principles learned using the model will transfer to other laparoscopic cases. Significant subjective improvements were reported in resident comfort level in assisting in or performing a laparoscopic Nissen fundoplication. CONCLUSIONS: The use of an inexpensive ex-vivo porcine training model increases resident comfort level in performing a Nissen fundoplication in the operating room. 相似文献
3.
4.
D. S. Grewal Bachi T. Hathiram 《Indian journal of otolaryngology and head and neck surgery》1997,49(2):125-129
Retraction pockets of the tympanic membrane are believed to be due to eustachian tube obstruction or malfunction. Our observations based on intraoperative findings suggest that the presence of a large sized mastoid antrum along with chronic eustachian tube obstruction plays an important role in the causation of retraction pockets. Granular myringitis may also occur in these circumstances when there is a recurrent eustachian tube blockage due to infection especially if the patient has received frequent and inadequate courses of antibiotics. The use of chromic catgut to create a healed air-filled middle ear space along with a canal wall down tympanomastoidectomy is discussed for their effective treatment. 相似文献
5.
Cap formation in a B-lymphocyte cell line is inhibited by pertussis toxin and phorbol ester. 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Immunology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We have examined concanavalin A (Con A)-induced cap formation in a B-lymphocyte derived cell line, LAZ-559. Treatment with pertussis toxin (PT) or phorbol-12-myristate-13-acetate (PMA) prior to exposure of the cells to Con A abolished the capping reaction. The possible role of calcium mobilization was tested using cells pre-loaded with the fluorescent dye Quin2. Both PT and PMA caused inhibition of calcium mobilization at concentrations similar to those observed for the inhibition of capping. The possible identity of the substrate for pertussis toxin was examined by carrying out ADP-ribosylation of the isolated plasma membranes using [alpha-32P]NAD and pertussis toxin. Several bands were observed at molecular weights of 109,000, 43,000, 34,000 and 22,000. Comparative labelling with cholera toxin revealed a separate band at 42,000. The bands at 43,000 and 34,000 are PT specific. Of these, the 43,000 band comigrated with the PT substrate that has been shown to regulate capping in human neutrophils (Lad et al., 1985a, 1986b). PMA-induced phosphorylation was examined in 32P-loaded cells, and multiple bands were observed to be labelled in a dose-dependent manner, at least two of which were very similar in mobility to the PT substrate. Our results suggest that regulation of calcium mobilization and the control of capping via a PMA-sensitive, GTP-binding protein are probably general phenomena observable in multiple cell systems. 相似文献
6.
Identification and characterization of CS20, a new putative colonization factor of enterotoxigenic Escherichia coli. 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
An enterotoxigenic Escherichia coli (ETEC) strain producing a previously undescribed putative colonization factor was isolated from a child with diarrhea in India. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of bacterial heat extracts revealed a polypeptide band of 20.8 kDa when the bacteria were grown at 37 degrees C which was absent after growth at 22 degrees C. A specific rabbit antiserum raised against the purified 20.8-kDa protein bound specifically to the fimbriae, as shown by immunoelectron microscopy, and inhibited bacterial adhesion to tissue-cultured Caco-2 cells. Transformation with a recombinant plasmid harboring the cfaD gene, which encodes a positive regulator for several ETEC fimbriae, induced hyperexpression of the 20.8-kDa fimbrial subunit and a substantial increase in the proportion of bacterial cells that were fimbriated. The N-terminal amino acid sequence of the polypeptide showed 65 and 60% identity to the PCFO20 and 987P fimbriae of human and porcine ETEC, respectively. We propose the term CS20 for this new putative colonization factor of human ETEC. 相似文献
7.
The multileaf travel range limitations on some linear accelerators require the splitting of a large intensity-modulated field into two or more adjacent abutting intensity-modulated subfields. The abutting subfields are then delivered as separate treatment fields. This workaround not only increases the treatment delivery time but it also increases the total monitor units (MU) delivered to the patient for a given prescribed dose. It is imperative that the cumulative intensity map of the subfields is exactly the same as the intensity map of the large field generated by the dose optimization algorithm, while satisfying hardware constraints of the delivery system. In this work, we describe field splitting algorithms that split a large intensity-modulated field into two or more intensity-modulated subfields with and without feathering, with optimal MU efficiency while satisfying the hardware constraints. Compared to a field splitting technique (without feathering) used in a commercial planning system, our field splitting algorithm (without feathering) shows a decrease in total MU of up to 26% on clinical cases and up to 63% on synthetic cases. 相似文献
8.
Simplified and accurate nonradioactive polynucleotide gene probe assay for identification of enterotoxigenic Escherichia coli. 总被引:2,自引:4,他引:2
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The present study describes a colony hybridization setup for identification of enterotoxigenic Escherichia coli obviating the need for advanced equipment and radioactive isotopes. With a modest laboratory arrangement, polynucleotide gene probes were produced in large quantities. The probes were labeled with digoxigenin and, after hybridization, detected with an antidigoxigenin alkaline phosphatase conjugate. With an established isotope-based oligonucleotide hybridization assay as reference, a blinded study on a large battery of enterotoxigenic and nonenterotoxigenic bacteria revealed a satisfactory sensitivity and specificity of the nonradioactive assay. 相似文献
9.
For several years, the primary function of CD40 ligand (CD40L) has been believed to be in regulation of contact-dependent, CD40-CD40L-mediated signals between B-and T-cells, which are essential for the regulation of thymus-dependent (TD) humoral immune responses. Recently, a flurry of reports indicate that CD40 is expressed by variety of cell types other than B-cells that include dendritic cells, follicular dendritic cells, monocytes, macrophages, fibroblasts, and endothelial cells. These studies show that CD40-CD40L interactions are important in inflammatory process. For the past few years, through the availability of CD40L-knockout mice, new data have emerged to support the belief that CD40L has many more functions than its role in TD humoral immunity. CD40L-deficient mice have provided significant information towards our understanding of the in vivo role of CD40L. The current picture that emerges indicates that CD40-CD40L interactions mediate many cell-mediated immune responses and T-cell-mediated effector functions that are required for proper functioning of the host defense system. This article focuses on the in vivo role of the CD40L in regulation of cell-mediated effector functions. 相似文献
10.