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   13449篇
  免费   672篇
  国内免费   100篇
耳鼻咽喉   87篇
儿科学   313篇
妇产科学   287篇
基础医学   1589篇
口腔科学   187篇
临床医学   837篇
内科学   3823篇
皮肤病学   216篇
神经病学   850篇
特种医学   455篇
外科学   2491篇
综合类   46篇
预防医学   256篇
眼科学   84篇
药学   856篇
中国医学   38篇
肿瘤学   1806篇
  2023年   102篇
  2022年   205篇
  2021年   377篇
  2020年   220篇
  2019年   299篇
  2018年   339篇
  2017年   259篇
  2016年   316篇
  2015年   345篇
  2014年   442篇
  2013年   485篇
  2012年   921篇
  2011年   937篇
  2010年   541篇
  2009年   464篇
  2008年   819篇
  2007年   849篇
  2006年   875篇
  2005年   836篇
  2004年   864篇
  2003年   815篇
  2002年   844篇
  2001年   188篇
  2000年   131篇
  1999年   197篇
  1998年   197篇
  1997年   151篇
  1996年   138篇
  1995年   101篇
  1994年   105篇
  1993年   80篇
  1992年   105篇
  1991年   94篇
  1990年   64篇
  1989年   59篇
  1988年   47篇
  1987年   47篇
  1986年   35篇
  1985年   42篇
  1984年   44篇
  1983年   22篇
  1982年   28篇
  1981年   19篇
  1980年   25篇
  1979年   29篇
  1978年   13篇
  1977年   21篇
  1976年   10篇
  1974年   13篇
  1971年   9篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
To help understand the molecular mechanisms of Pasteurella multocida toxin (PMT) action, we searched for a cellular protein interacting with PMT. The ligand overlay assay revealed a 60-kDa cellular protein that binds to a region from the 840th to 985th amino acids of the toxin. This protein was identified as vimentin by peptide mass fingerprinting. The N-terminal head domain of vimentin was further found to be responsible for the binding to the toxin.  相似文献   
102.
Ovarian mature cystic teratomas (MCT) uncommonly undergo malignant transformation to squamous cell carcinoma (SCC). While alterations in the p53 tumor suppressor gene and protein have been shown, few studies have analyzed other molecular changes leading to this malignant conversion. The purpose of the present study was to investigate 21 samples of SCC arising in MCT for altered expression in known p53‐ and p16/Rb‐dependent cell cycle regulatory proteins, and the association between their expression and cellular proliferation and histological features. Overexpression of the p53 protein was observed in 14 SCC (67%), while four (19%) had point mutations in the p53 gene. Reduced expression of the p16 protein was observed in 18 SCC (86%), while p16 gene alterations (hypermethylation (29%) and point mutation (33%)) were found in 11 (52%). Furthermore, a statistically significant correlation was observed between p53 and Rb overexpression (P = 0.0010), and the overexpression of both p53 and Rb was respectively significantly correlated with increased cellular proliferation. The results indicate that alterations in both the p53 and p16‐Rb pathways are associated with SCC arising in MCT.  相似文献   
103.
BACKGROUND: Either omega-5 gliadin or high molecular weight glutenin is known to be a major allergen in wheat-dependent exercise-induced anaphylaxis (WDEIA). It is generally considered that gluten specific IgE score is more reliable than that of wheat specific IgE score for the diagnosis of WDEIA. Our aim was to verify the significance of gluten specific IgE in the diagnosis of WDEIA. METHODS: We evaluated the result of gluten CAP-RAST score and omega-5 gliadin specific IgE score on four WDEIA patients who visited our hospital during the years 2004 and 2005, whose diagnosis were onfirmed by prick tests, immunoblot tests and provocation tests. RESULTS: Contrary to our expectations, all four patients showed negative gluten CAP-RAST scores, however all patient's omega-5 gliadin specific IgE scores were positive. CONCLUSION: Our results suggest that gluten specific CAP-RAST score is unreliable in the diagnosis of WDEIA. On the other hand omega-5 gliadin specific IgE score is possibly a better candidate as a diagnostic tool for WDEIA.  相似文献   
104.
105.
This is a report of a vaccine trial directed against Babesia gibsoni infection in dogs with the use of the recombinant antigen P50. Dogs immunized with P50 showed partial protection manifested as a significantly low level of parasitemia. The results indicated that P50 is a primary vaccine candidate molecule against canine B. gibsoni infection.  相似文献   
106.
The isomorphic response of Koebner can be observed not only in psoriasis, but also in other diseases, such as lichen planus and some systemic diseases including LE (lupus erythematosus) or sarcoidosis. Several clinical findings in LE skin were presented and discussed in this review. The mutually-interactive-, negative-, and internal-Koebner phenomena were introduced and discussed with some speculative views. Many forms of environmental stress on the skin were reported as provocating factors of the Koebner phenomenon, including trauma, scratching, UV-exposure, and various types of dermatitis. Clinical observations of the nature, localization, and movement of lesions should be carefully made. The pathophysiology of the Koebner phenomenon may be classified into two steps. A first non-specific inflammatory step and a second disease-specific step. The inflammatory products released from the first step would be targeted in the second step. In the first step, there could be many substances including cytokines, stress proteins, adhesion molecules, or autoantigens translocated from intra-cellular areas. In the second step after latent periods, there may be disease-specific reactions, including ones by T-cells, B-cells, autoantibodies, and immune deposits, under the restriction of genetic backgrounds. The Koebner phenomenon may prove useful in understanding the pathophysiology of diseases of unknown origin.  相似文献   
107.
108.
In 2004, the Japanese Committee of Clinical Laboratory Standards (JCCLS) published a standard phlebotomy guideline, which not only ensures the safety of the patients and phlebotomists but is adopted to the healthcare setting in Japan. This phlebotomy standard is also essential for the standardization of clinical laboratory tests. This guideline was completed on the basis of current phlebotomy procedures widely in use in Japan using phlebotomy standards in the USA as references, while reconsidering their scientific reasoning as far as possible. At the same time, factors such as practicality and cost benefit were taken into account. The content of the guideline includes necessary facilities and equipment, a step by step safe but practical venipuncture procedure, an explanation of the individual steps, and other supplementary information such as alternative methods. The first edition, published as tentative guideline, is planned to be revised after a set period of time based on the comments and suggestions from a wide range of people concerned, so that it can be published as an approved guideline.  相似文献   
109.
To develop a new measurement tool for quantitatively detecting the finger movement of a patient with Parkinson's disease (PD), we designed a magnetic sensing system consisting of a magnetic induction coil, a sensing coil, and a circuit unit. The sensing coil detects the inducted magnetic field that varies with the distance between the two coils, and the detected signals are demodulated in the circuit unit in order to obtain the variation voltage from the oscillation frequency. To obtain a coefficient for converting voltage to distance, we measured the output voltages for seven fixed finger positions of 12 normal volunteers. The voltage differences corresponding to the finger movement in 20 PD patients, six age-matched controls, and 12 normal volunteers were then recorded for 30s. To investigate the velocity and acceleration of the finger movement, we calculated their waveforms from the measured displacement waveform. We also detected the main frequency of the tapping rhythm by using a fast Fourier transform (FFT). The averaged amplitude of each waveform decreased with the disorder in the Hoehn-Yahr (HY) stage, while the averaged tapping frequency of PD patients did not have any correlation with this stage. It can be concluded that this magnetic sensing system can assess finger movement quantitatively.  相似文献   
110.
Ubiquitination, a modification in which single or multiple ubiquitin molecules are attached to a protein, serves as a signalling function that controls a wide variety of cellular processes. To date, two major forms of polyubiquitin chain have been functionally characterized, in which the isopeptide bond linkages involve Lys48 or Lys63. Lys48-linked polyubiquitin tagging is mostly used to target proteins for degradation by the proteasome, whereas Lys63-linked polyubiquitination has been linked to numerous cellular events that do not rely on degradative signalling via the proteasome. Apparently linkage-specific conformations of polyubiquitin chains are important for these cellular functions, but the structural bases distinguishing Lys48- and Lys63-linked chains remain elusive. Here, we report NMR and small-angle X-ray scattering (SAXS) studies on the intersubunit interfaces and conformations of Lys63- and Lys48-linked di- and tetraubiquitin chains. Our results indicate that, in marked contrast to Lys48-linked chains, Lys63-linked chains are elongated molecules with no stable non-covalent intersubunit interfaces and thus adopt a radically different conformation from that of Lys48-linked chains.  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