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   1385篇
  免费   112篇
  国内免费   2篇
耳鼻咽喉   25篇
儿科学   38篇
妇产科学   30篇
基础医学   246篇
口腔科学   27篇
临床医学   160篇
内科学   246篇
皮肤病学   46篇
神经病学   108篇
特种医学   30篇
外国民族医学   1篇
外科学   128篇
综合类   3篇
一般理论   1篇
预防医学   140篇
眼科学   28篇
药学   81篇
中国医学   1篇
肿瘤学   160篇
  2023年   25篇
  2022年   24篇
  2021年   76篇
  2020年   48篇
  2019年   46篇
  2018年   66篇
  2017年   36篇
  2016年   37篇
  2015年   43篇
  2014年   58篇
  2013年   64篇
  2012年   145篇
  2011年   106篇
  2010年   47篇
  2009年   46篇
  2008年   84篇
  2007年   74篇
  2006年   74篇
  2005年   60篇
  2004年   62篇
  2003年   54篇
  2002年   52篇
  2001年   11篇
  2000年   11篇
  1999年   12篇
  1998年   13篇
  1997年   5篇
  1996年   7篇
  1995年   6篇
  1994年   4篇
  1992年   9篇
  1991年   9篇
  1990年   3篇
  1988年   3篇
  1986年   6篇
  1985年   7篇
  1984年   3篇
  1983年   6篇
  1982年   3篇
  1981年   4篇
  1978年   2篇
  1977年   2篇
  1974年   3篇
  1972年   5篇
  1971年   3篇
  1966年   2篇
  1965年   3篇
  1964年   3篇
  1961年   3篇
  1954年   4篇
排序方式: 共有1499条查询结果,搜索用时 15 毫秒
1.
Gorlin syndrome (naevoid basal cell carcinoma syndrome) is a genetically linked disorder characterized by the development of multiple basal cell carcinomas (BCCs) throughout life. Cumulative surgery, cryotherapy and other conventional interventions can result in significant disfigurement by middle age. Radiotherapy is contra-indicated because the mutated gene underlying the syndrome, ‘PTCH’, increases sensitivity to ionising radiation, so there is significant likelihood of inducing further tumours in and around the irradiated area. Photodynamic therapy offers a non-invasive treatment option for patients with this condition, with the added advantage of causing minimal scarring.  相似文献   
2.
Parkin mutations account for the majority of familial and sporadic early onset Parkinson's disease (EOPD) cases with a known genetic association. More than 100 mutations have been described in the Parkin gene that includes homozygous, compound heterozygous, and single heterozygous mutations. We have designed a Parkin mutation genotyping array (gene chip) that includes published Parkin sequence variants and allows their simultaneous detection. The chip was validated by screening 85 PD cases and 47 controls previously tested for Parkin mutations. Similar genotyping microarrays have been developed for other genetically heterogeneous diseases including age-related macular degeneration. Here, we show the utility of a genotyping array for Parkinson's disease by analysis of 60 subjects from the Genetic Epidemiology of Parkinson Disease (GEPD) study that includes 15 early-onset PD case probands and 45 relatives.  相似文献   
3.
4.
The proteolytic cleavage product of complement component 3, (C3a), like C4a and C5a, is a potent anaphylatoxin and induces the production of inflammatory mediators in phagocytes. Notably, mast cells respond to C3a with the release of vasoactive substances, including histamine. We have examined the function and receptor binding of C3a in a human leukemic mast cell line, HMC-1. Similar to chemoattractant agonists in leukocytes, C3a induced rapid cytosolic free calcium concentration increases in HMC-1 cells. EGTA did not diminish this response, indicating that mobilizable Ca2+ was from intracellular stores. Receptors for C3a in HMC-1 cells couple in part to Bordetella pertussis toxin-sensitive G-proteins and, therefore, appear to belong to the family of serpentine receptors that require G-proteins for signal transduction. HMC-1 cells express two types of C3a receptors, C3aR1 and C3aR2, that were shown to bind 125I-C3a with high-(Kd1 = 2.1–4.8 nM) or low-affinity (Kd2 = 30–150 nM), and both receptors are expressed at high level: 3 × 105–6 × 105 C3aR1/cell and 5 × 105–2.3 × 106 C3aR2/cell. Results from cross-linking experiments with 125I-C3a fully agree with the presence of two different classes of C3a receptors in HMC-1 cells. Two membrane proteins with apparent molecular masses of 54–61 kDa (p57) and 86–107 kDa (p97) could be covalently modified with 125I-C3a, and this cross-linking was inhibited with an excess of unlabeled C3a. Many of the known agonists for leukocytes including 13 chemokines (IL-8, NAP-2, GROα, ENA-78, IP10, PF4, MCP-1, 2 and 3, RANTES, MIP-1α, MIP-1β and 1309), three neuropeptides (neuropeptide Y, somatostatin and calcitonin), as well as C5a, did not activate HMC-1 cells, indicating that C3a is one of a few protein ligands for which this cell line expresses specific receptors. The apparent selectivity for C3a and the abundant expression of C3a receptors make the HMC-1 cell line an excellent choice for the cloning of the receptor genes.  相似文献   
5.
The prognostic value of early hepatitis C virus (HCV)-RNA load was evaluated among nonresponder patients to previous interferon (IFN) therapy treated with daily IFN and ribavirin. One hundred-six nonresponders (83 men), mean age 44.8 +/- 11 years, were treated with IFN-alpha 2b 3 MU/day for 24 weeks, followed by 3 MU x 3/week for 24 weeks plus ribavirin 1-1.2 g/day for 48 weeks. HCV RNA was quantified by Versant HCV RNA 3.0 assay (Bayer). The predictive values of the baseline and the change in viral load at week 1, 4, and 12 for sustained virological responses were analyzed using receiver operating characteristic (ROC) curves, as well as predictive values of >2 log(10) drop from baseline by weeks 1, 4, and 12 in combination with undetectable HCV RNA for sustained virological response. Thirty-two patients (30.2%) were sustained virological responders. The highest area under the curve was obtained at week 4. The unquantifiable HCV RNA level, in combination with at least a 2 log(10) drop in viral load by week 4 and week 12, had a negative predictive value of 96% and 97%, respectively. Nonresponse can be predicted as early as week 4 or week 12 in nonresponders treated with daily IFN and ribavirin.  相似文献   
6.
An 8-year-old male with a complex developmental syndrome and severe obesity was heterozygous for a de novo missense mutation resulting in a Y722C substitution in the neurotrophin receptor TrkB. This mutation markedly impaired receptor autophosphorylation and signaling to MAP kinase. Mutation of NTRK2, which encodes TrkB, seems to result in a unique human syndrome of hyperphagic obesity. The associated impairment in memory, learning and nociception seen in the proband reflects the crucial role of TrkB in the human nervous system.  相似文献   
7.
The study aim was to evaluate the effect of bone marrow stromal cells (BMSCs) cultured in titanium fiber mesh and implanted in a rat cranial defect. A total of 24 titanium meshes were placed in a tube containing 10 ml BMSC suspension (3 x 10(6)cells/ml) and the tube was rotated on a rotation plate (2 rpm) during 3 h. Thereafter, meshes with cells were subcultured for 1 day under standard conditions. Cell-loaded implants and non-cell-loaded controls were placed in a 8 mm cranial defect and retrieved after 3, 15 and 30 days of implantation. Histology showed that after 3 days of implantation, the mesh porosity of both implant groups was mainly invaded with blood cells. On the other hand, at 15 days of implantation, the cell-loaded implants were filled for 15 +/- 10% of their volume with bone, while the controls showed 1.5 +/- 3.5% of bone. The 30-day cell-loaded implants showed 40 +/- 12.5% of bone and the 30-day control implants 17 +/- 14.5%. At both implantation times the differences were statistically significant. Therefore, we conclude that inoculation of titanium fiber mesh with BMSCs can improve the bone healing capacity of this material.  相似文献   
8.
Zusammenfassung Die vorliegenden Untersuchungen haben zu folgendem Ergebnis geführt:1. Die im Serum nachweisbare Streptolysinhemmwirkung zeigt Beziehungen zum Phosphatidgehalt des-Glubulinbereiches und zu den Eiweißanteilen der Albumin-, 2-Globulin- und-Globulinfraktion.2. Neben der durch Antikörper bedingten Strepto-lysinhemmwirkung — die wohl in der-Globulinfraktion lokalisicrt ist — sind noch weitere unspezifische Serumfaktoren nachzuweisen, die eine derartige Hemmwirkung entfalten. Sie werden von uns als Streptolysininhibitoren bezeichnet.3. Der für die unspezifische Hemmwirkung maßgebliche Lipoidanteil ist an Bentonit adsorbierbar, und zwar werden hohe wie niedrige Titer um etwa 25% reduziert.An Bentonit werden neben den Lipoiden auch gewisse Eiweißanteile adsorbiert. Von den danach im Serum verbliebenen Eiweißfraktionen zeigen die Albumin-, 2-Globulin- und-Globulinfraktion statistisch gesicherte Beziehungen zu dem verbliebenen Resttiter.4. Die Bedeutung dieser Ergebnisse für die klinische Bewertung des Streptolysintiters wird diskutiert.  相似文献   
9.
CARMA1 is a lymphocyte-specific member of the membrane-associated guanylate kinase (MAGUK) family of scaffolding proteins, which coordinate signaling pathways emanating from the plasma membrane. CARMA1 interacts with Bcl10 via its caspase-recruitment domain (CARD). Here we investigated the role of CARMA1 in T cell activation and found that T cell receptor (TCR) stimulation induced a physical association of CARMA1 with the TCR and Bcl10. We found that CARMA1 was constitutively associated with lipid rafts, whereas cytoplasmic Bcl10 translocated into lipid rafts upon TCR engagement. A CARMA1 mutant, defective for Bcl10 binding, had a dominant-negative (DN) effect on TCR-induced NF-kappa B activation and IL-2 production and on the c-Jun NH(2)-terminal kinase (Jnk) pathway when the TCR was coengaged with CD28. Together, our data show that CARMA1 is a critical lipid raft-associated regulator of TCR-induced NF-kappa B activation and CD28 costimulation-dependent Jnk activation.  相似文献   
10.
Kallmann syndrome (KAL) combines hypogonadotropic hypogonadism and anosmia. Hypogonadism is due to Gonadotropin Releasing Hormone (GnRH) deficiency and anosmia is related to hypoplasia of the olfactory bulbs. Occasional symptoms include renal agenesis, bimanual synkinesia, cleft lip palate, dental agenesis. KAL is genetically heterogeneous and two genes have so far been identified, namely KAL1 (Xp22.3) and FGFR1/KAL2 (8p12), which underlie the X chromosome‐linked form and an autosomal dominant form of the disease, respectively. We studied a cohort of 98 unrelated Caucasian KAL patients. We identified KAL1 mutations in 14 patients, of which 7 (c.3G>A (p.M1?), g.IVS1+1G>T, c.570_571insA (p.R191fsX14), c.784G>C (p.R262P), c.958G>T (p.E320X), c.1651_1654delinsAGCT (p.P551_E552delinsSX), c.1711T>A (p.W571R)) have not been previously reported. In addition, we found FGFR1 mutations in 7 patients, namely c.303G>A (p.V102I), C.385A>C (p.D129A), c.810G>A (p.V273M), c.1093_1094delAG (p.R365fsX41), c.1561G>A (p.A520T), c.1836_1837insT (p.Y613fsX42), c.2190C>G (p.Y730X), all of which were novel mutations. In this study, unilateral renal agenesis and bimanual synkinesia were exclusively found associated with KAL1mutations, cleft palate and dental agenesia with FGFR1mutations. © 2004 Wiley‐Liss, Inc.  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