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   10732篇
  免费   547篇
  国内免费   72篇
耳鼻咽喉   155篇
儿科学   221篇
妇产科学   134篇
基础医学   1391篇
口腔科学   188篇
临床医学   576篇
内科学   2711篇
皮肤病学   244篇
神经病学   731篇
特种医学   582篇
外科学   1684篇
综合类   24篇
一般理论   1篇
预防医学   302篇
眼科学   152篇
药学   614篇
中国医学   14篇
肿瘤学   1627篇
  2023年   57篇
  2022年   97篇
  2021年   197篇
  2020年   104篇
  2019年   137篇
  2018年   162篇
  2017年   146篇
  2016年   196篇
  2015年   215篇
  2014年   269篇
  2013年   299篇
  2012年   494篇
  2011年   517篇
  2010年   359篇
  2009年   285篇
  2008年   551篇
  2007年   554篇
  2006年   568篇
  2005年   599篇
  2004年   636篇
  2003年   655篇
  2002年   648篇
  2001年   234篇
  2000年   270篇
  1999年   262篇
  1998年   149篇
  1997年   155篇
  1996年   141篇
  1995年   135篇
  1994年   101篇
  1993年   102篇
  1992年   202篇
  1991年   213篇
  1990年   221篇
  1989年   195篇
  1988年   186篇
  1987年   133篇
  1986年   124篇
  1985年   118篇
  1984年   101篇
  1983年   73篇
  1982年   54篇
  1981年   33篇
  1980年   34篇
  1979年   52篇
  1978年   49篇
  1977年   38篇
  1976年   23篇
  1975年   34篇
  1974年   39篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
Mouse Formin (Fmn1) protein plays a key role in limb morphogenesis. Fmn1 is one of the actin regulators with scaffold function, interacting with Profilin, SRC, EMS1, FNBP1, FNBP2, FNBP3, FNBP4, WBP4 and alpha-catenin. Fmn1, Fmn2, FHOD1, FHOD3, GRID2IP and FHDC1 are non-FDD-type Formin homology proteins, while FMNL1, FMNL2, FMNL3, DIAPH1, DIAPH2, DIAPH3, DAAM1 and DAAM2 are FDD-type Formin homology proteins. Here, we identified the human FMN1 gene by using bioinformatics. The complete coding sequence of human FMN1 cDNA was determined by assembling AC055874.8 genome sequence (nucleotide position 178207-180073), AI040235 EST (complementary sequence for nucleotide position 331-156) and FLJ45135 cDNA (nucleotide position 319-3310). FMN1 isoform 1 (exons 1-18) and FMN isoform 2 (exons 1b and 3-18) were transcribed due to alternative splicing of the alternative promoter type. The FMN1 gene at human chromosome 15q13.3 was located between CKTSF1B1 (Gremlin) and RYR3 genes. The Xenopus fmn1 gene was identified within the Xenopus genome sequence CH216-24N20 (AC147835.1). The FMH1 domain (codon 1-120 of FMN1) and FMH2 domain (codon 683-835 of FMN1) were identified as novel regions conserved among human FMN1, mouse Fmn1, and Xenopus fmn1. The FMH2 domain was almost identical to the alpha-catenin binding domain of mouse Fmn1. Human FMN1 (1419 aa), showing 77.1% total amino-acid identity with mouse Fmn1, was found consisting of FMH1, FMH2, FH1 and FH2 domains. This is the first report on the identification and characterization of the human FMN1 gene as well as the FMH1 and FMH2 domains.  相似文献   
102.
Primary sclerosing cholangitis (PSC) is known to be frequently associated with inflammatory bowel diseases. In a rat with self-filling blind loop (SFBL), a proposed animal model for PSC, hepatobiliary inflammation has previously been demonstrated. In this study, we assessed the involvement of lipopolysaccharide (LPS), a bacterial endotoxin, in the pathogenesis of hepatobiliary inflammation of the SFBL model. The hepatic localization of LPS was examined by immunohistochemistry using an anti-lipid A antibody. The portal blood concentration of LPS was measured by an endotoxin-specific chromogenic Limulus test (Endospecy test). LPS was localized in the biliary epithelial cells (BECs) of rats with SFBL, and the portal blood concentration of LPS was significantly higher than that of sham-operated rats. Development of hepatobiliary inflammation, peribiliary fibrosis, and injury to the intestinal mucosa were histologically confirmed. Constriction in the biliary trees was radiologically demonstrated. These findings suggested that abnormal accumulation of LPS, which may be derived from portal blood, in BECs was involved in the pathogenesis of hepatobiliary inflammation with intestinal injury.  相似文献   
103.
104.
BACKGROUND: The loop-mediated isothermal amplification (LAMP) method is a novel technique for the amplification of specific DNA sequences. OBJECTIVES: To establish the LAMP method for amplifying Epstein-Barr virus (EBV) DNA and to examine its reliability for the detection of EBV DNA in clinical specimens. STUDY DESIGN: Sera from 108 patients, who were initially suspected of primary EBV infection, were tested by the EBV LAMP method, and the results were compared with those of the real-time PCR assay. Serological examination was regarded as the standard diagnostic method. RESULTS: To diagnose primary EBV infection, the sensitivity of LAMP was 86.4% and the specificity was 100%. The sensitivity of the real-time PCR assay was 84.1% and the specificity was 98.4%. Longitudinal analysis showed that the detection rate of EBV DNA in serum by the LAMP method decreased with time in accordance with the decrease of the EBV load. EBV DNA could not be detected in serum 40 days after onset of symptoms. CONCLUSIONS: These results indicate that the sensitivity and specificity of the LAMP method are comparable to those of real-time PCR and that detecting EBV DNA in serum by this method is potentially useful for diagnosing primary EBV infection.  相似文献   
105.
BAFF-receptor (BAFF-R) is required for the successful maturation and survival of B-cells. We developed an anti-human BAFF-R monoclonal antibody (mAb), 8A7. The reactivity of 8A7 in normal and neoplastic tissue was examined by performing immunohistochemistry on paraffin-embedded sections. 8A7 reacted with lymphocytes in the mantle and marginal zones, but not with lymphocytes in the interfollicular area. Lymphocytes in the germinal centers were found to be negative or occasionally weakly positive for 8A7. BAFF-R expression was found only in B-cell lymphoma (44/80, positive cases/examined cases): B-lymphoblastic lymphoma 0/3, B-chronic lymphocytic leukemia/small lymphocytic lymphoma 4/4, mantle cell lymphoma 9/11, follicular lymphoma 10/14, diffuse large B-cell lymphoma (DLBCL) 11/25, marginal zone B-cell lymphoma 8/10, lymphoplasmacytic lymphoma 2/2, plasma cell myeloma 0/2, and Burkitt lymphoma 0/9, but not in T/NK cell lymphomas (0/19) or Hodgkin lymphoma (0/10). BAFF-R was expressed in most low-grade B-cell neoplasms and a small number of DLBCL, suggesting that BAFF-R may play an important role in the proliferation of neoplastic lymphoid cells. Thus, the mAb is very useful for further understanding of both healthy B-cell biology and its pathogenic neoplasms.  相似文献   
106.
107.
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   
108.
In acute hypotension, an automated drug infusion system to control mean arterial blood pressure (MAP) has not been previously studied, though many investigations have examined the use of vasodilating drugs to control MAP in postoperative hypertension. Therefore, we examined an automated control of MAP during acute hypotension using a neural network (NN) approach. A proportional-integral-derivative (PID) control, an adaptive predictive control using a NN (APC(NN)), a combined control of APC(NN) and PID (APC(NN-PID)), a fuzzy control, and a model predictive control were tested in computer simulation based on the MAP response to norepinephrine (NE) of 25 microg ml(-1). In six anesthetized rabbits, using the NE of 25 microg ml(-1), the PID control, APC(NN), and APC(NN-PID) prevented severe hypotension compared to an uncontrolled condition. Under PID control, four of the six animals showed MAP oscillation. Using NE of 50 microg ml(-1), the rabbits recovered from acute hypotension for all systems tested but showed sustained MAP oscillation during PID control. In conclusion, utilization of a NN for adaptive predictive control systems could facilitate the development of an automated drug infusion apparatus because it provides robust control even when acute or large perturbations and inter-individual differences in the sensitivity to therapeutic agents occur.  相似文献   
109.
110.
Tocopherol-associated protein (TAP) was expressed in mouse mast cells. TAP was predominantly localized in the cytoplasm, and the subcellular localization was not changed by alpha-tocopherol. The results suggest that the physiological role of TAP in mast cells is not regulation of tocopherol function but an as-yet-unidentified activity.  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