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   937篇
  免费   93篇
  国内免费   2篇
耳鼻咽喉   25篇
儿科学   53篇
妇产科学   16篇
基础医学   123篇
口腔科学   33篇
临床医学   109篇
内科学   284篇
皮肤病学   10篇
神经病学   118篇
特种医学   32篇
外科学   101篇
综合类   6篇
预防医学   29篇
眼科学   18篇
药学   30篇
肿瘤学   45篇
  2023年   8篇
  2022年   3篇
  2021年   30篇
  2020年   21篇
  2019年   35篇
  2018年   29篇
  2017年   27篇
  2016年   30篇
  2015年   42篇
  2014年   30篇
  2013年   61篇
  2012年   89篇
  2011年   83篇
  2010年   38篇
  2009年   37篇
  2008年   49篇
  2007年   63篇
  2006年   50篇
  2005年   56篇
  2004年   53篇
  2003年   37篇
  2002年   34篇
  2001年   12篇
  2000年   11篇
  1999年   10篇
  1998年   8篇
  1997年   5篇
  1995年   3篇
  1993年   8篇
  1992年   5篇
  1991年   7篇
  1990年   1篇
  1989年   3篇
  1988年   6篇
  1987年   3篇
  1986年   7篇
  1985年   4篇
  1984年   6篇
  1983年   3篇
  1982年   1篇
  1979年   1篇
  1978年   3篇
  1977年   2篇
  1976年   5篇
  1975年   1篇
  1974年   2篇
  1972年   2篇
  1971年   1篇
  1970年   3篇
  1969年   1篇
排序方式: 共有1032条查询结果,搜索用时 15 毫秒
1.
2.
A technique for temporary ventricular drainage using a subcutaneous pouch is described for use in neonatal hydrocephalus after intraventricular hemorrhage. The advantages include continuous, valve-regulated ventricular decompression, no exposed tubing, avoidance of electrolyte imbalance and of the loss of CSF, obviation of the need for repeated tapping, and the ability to convert to a peritoneal shunt on an elective basis.  相似文献   
3.
This paper considers the immediate post‐traumatic reactions of rescue personnel who were exposed to the Hilton Hotel bombing in Sinai. The entire rescue personnel (n = 26) were assessed and separated into two groups on the basis of previous exposure to the same type of trauma. The results suggest that among rescue personnel, those with previous exposure had a lower level of post‐traumatic symptoms than those who were being exposed for the first time. This supports the hypothesis that previous exposure to the same type of trauma has an immunizing effect for subsequent same type of traumatic event among rescue personnel. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   
4.
A community-orientated programme for the control of hypertension, atherosclerotic disease, and diabetes has been developed in a family practice in a neighbourhood of Jerusalem. Intervention is directed mainly towards the control of risk factors associated with these diseases.

The programme has specific objectives for diet, smoking, obesity, blood pressure, serum cholesterol, glucose intolerance, and diabetes mellitus, and the identification and treatment of patients with cardiovascular diseases. The survey seeks to identify the nature and extent of problems, intervention by medicinal and educational means, and continuing surveillance and evaluation.

The programme aims to test and demonstrate the feasibility of carrying out multifactorial community health care within the framework of a family practice, thereby developing a joint practice of primary health care and community medicine.

  相似文献   
5.
We evaluated a protocol for the accelerated detection of extended-spectrum beta-lactamases (ESBLs) in gram-negative bloodstream pathogens. Two hundred eighty-three blood culture bottles were subjected to direct ESBL testing by inoculating samples directly from blood culture bottles onto agar plates containing cefotaxime and ceftazidime disks, with and without clavulanate. Standard ESBL testing in accordance with the NCCLS guidelines after subculturing on agar plates was performed in parallel. Results of the direct ESBL testing were reported 2.3 days sooner and were comparable to those of the standard NCCLS method with sensitivity, specificity, and positive and negative predictive values of 100, 98, 94, and 100%, respectively.  相似文献   
6.

Background:

When Saccharomyces cerevisiae cells that have begun meiosis are transferred to mitotic growth conditions (‘return-to-growth’, RTG), they can complete recombination at high meiotic frequencies, but undergo mitotic cell division and remain diploid. It was not known how meiotic recombination intermediates are repaired following RTG. Using molecular and cytological methods, we investigated whether the usual meiotic apparatus could repair meiotically induced DSBs during RTG, or whether other mechanisms are invoked when the developmental context changes.

Results:

Upon RTG, the rapid disappearance of meiotic features—double-strand breaks in DNA (DSBs), synaptonemal complex (SC), and SC related structures—was striking. In wild-type diploids, the repair of meiotic DSBs during RTG was quick and efficient, resulting in homologous recombination. Kinetic analysis of double-strand breakage and recombination indicated that meiotic DSB formation precedes the commitment to meiotic levels of recombination. DSBs were repaired in RTG in dmc1, but not rad51 mutants, hence repair did not occur by the usual meiotic mechanism which requires the Dmc1 gene product. In haploids, DSBs were also repaired quickly and efficiently upon RTG, showing that DSB repair did not require the presence of a homologous chromosome. In all strains examined, SC and related structures were not required for DSB repair or recombination following RTG.

Conclusions:

At least two pathways of DSB repair, which differ from the primary meiotic pathway(s), can occur during RTG: One involving interhomologue recombination, and another involving sister-chromatid exchange. DSB formation precedes commitment to recombination. SC elements appear to prevent sister chromatid exchange in meiosis.
  相似文献   
7.
The diagnosis of bloodstream infection with coagulase-negative staphylococci is frequently based on the isolation of the same organism from more than one blood culture. Phenotypic variation is a common characteristic of pathogenic strains of Staphylococcus epidermidis which may affect species identification by the microbiology laboratory. We describe a patient with a new onset of nephritis and gram-positive bacteremia. Gram-positive cocci grew in multiple blood cultures and were identified by the Vitek 2 system as Kocuria varians, Staphylococcus hyicus, and S. epidermidis. Bacterial isolates grew on blood agar and Congo red agar plates as two distinct morphotypes and exhibited phenotypic variation. Neither morphotype could be identified by the API-Staph assay. Cellular fatty acid analysis identified one of the morphotypes as S. epidermidis but could not identify the other morphotype. All isolates were found to be identical by pulsed-field gel electrophoresis, and both colonial morphotypes were identified as S. epidermidis by 16S ribosomal gene sequencing. Phenotypic variation of S. epidermidis may affect identification to the species level by phenotype-based identification systems. Caution should be exercised when differentiating between true infection and contamination based on strain identification.  相似文献   
8.
The burgeoning field of leukocyte trafficking has created new and exciting opportunities in the clinic. Trafficking signals are being defined that finely control the movement of distinct subsets of immune cells into and out of specific tissues. Because the accumulation of leukocytes in tissues contributes to a wide variety of diseases, these 'molecular codes' have provided new targets for inhibiting tissue-specific inflammation, which have been confirmed in the clinic. However, immune cell migration is also critically important for the delivery of protective immune responses to tissues. Thus, the challenge for the future will be to identify the trafficking molecules that will most specifically inhibit the key subsets of cells that drive disease processes without affecting the migration and function of leukocytes required for protective immunity.  相似文献   
9.
The development of the cerebral microvasculature of the rat was studied during three successive postnatal periods, namely: 1) neonatal period, i.e., 1 to 9 days after birth (capillary sprouting period); 2) myelinization period, i.e., 10 to 20 days; and 3) young adult period, i.e., 2 to 3 months. The survey covered structural aspects and distribution of binding sites for anionic or cationic probes and for albumin-gold complexes on the luminal surface of the microvascular endothelium. The salient results are: a) an extensive development of the endoplasmic reticulum of endothelial cells during the first period (presumably in relation with the production of basement membrane components); b) the high surface density of coated pits and coated vesicles that peaks during the myelinization period; c) the paucity of plasmalemmal vesicle and their differential distribution (their volume density is higher in the endothelium of arterioles than in that of capillaries and venules); d) the existence of an extensive smooth surface tubular system in the cytoplasm of endothelial cells, whose structural connections and functional significance remains to be established; and e) the presence of pericytes with elaborate interactions with endothelia in the early developmental periods. Labeling by perfused tracers indicates an uneven patchy distribution of binding sites for cationic ferritin (generally limited to the plasmalemma proper) and a more even distribution of binding sites for cationic and anionic hemeundecapeptides. Binding patterns did not change during the developmental periods studied. No binding sites were detected for albumin-gold complexes.  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